1 /* Common subexpression elimination for GNU compiler.
2 Copyright (C) 1987, 88, 89, 92, 93, 1994 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
22 /* Must precede rtl.h for FFS. */
27 #include "hard-reg-set.h"
30 #include "insn-config.h"
35 /* The basic idea of common subexpression elimination is to go
36 through the code, keeping a record of expressions that would
37 have the same value at the current scan point, and replacing
38 expressions encountered with the cheapest equivalent expression.
40 It is too complicated to keep track of the different possibilities
41 when control paths merge; so, at each label, we forget all that is
42 known and start fresh. This can be described as processing each
43 basic block separately. Note, however, that these are not quite
44 the same as the basic blocks found by a later pass and used for
45 data flow analysis and register packing. We do not need to start fresh
46 after a conditional jump instruction if there is no label there.
48 We use two data structures to record the equivalent expressions:
49 a hash table for most expressions, and several vectors together
50 with "quantity numbers" to record equivalent (pseudo) registers.
52 The use of the special data structure for registers is desirable
53 because it is faster. It is possible because registers references
54 contain a fairly small number, the register number, taken from
55 a contiguously allocated series, and two register references are
56 identical if they have the same number. General expressions
57 do not have any such thing, so the only way to retrieve the
58 information recorded on an expression other than a register
59 is to keep it in a hash table.
61 Registers and "quantity numbers":
63 At the start of each basic block, all of the (hardware and pseudo)
64 registers used in the function are given distinct quantity
65 numbers to indicate their contents. During scan, when the code
66 copies one register into another, we copy the quantity number.
67 When a register is loaded in any other way, we allocate a new
68 quantity number to describe the value generated by this operation.
69 `reg_qty' records what quantity a register is currently thought
72 All real quantity numbers are greater than or equal to `max_reg'.
73 If register N has not been assigned a quantity, reg_qty[N] will equal N.
75 Quantity numbers below `max_reg' do not exist and none of the `qty_...'
76 variables should be referenced with an index below `max_reg'.
78 We also maintain a bidirectional chain of registers for each
79 quantity number. `qty_first_reg', `qty_last_reg',
80 `reg_next_eqv' and `reg_prev_eqv' hold these chains.
82 The first register in a chain is the one whose lifespan is least local.
83 Among equals, it is the one that was seen first.
84 We replace any equivalent register with that one.
86 If two registers have the same quantity number, it must be true that
87 REG expressions with `qty_mode' must be in the hash table for both
88 registers and must be in the same class.
90 The converse is not true. Since hard registers may be referenced in
91 any mode, two REG expressions might be equivalent in the hash table
92 but not have the same quantity number if the quantity number of one
93 of the registers is not the same mode as those expressions.
95 Constants and quantity numbers
97 When a quantity has a known constant value, that value is stored
98 in the appropriate element of qty_const. This is in addition to
99 putting the constant in the hash table as is usual for non-regs.
101 Whether a reg or a constant is preferred is determined by the configuration
102 macro CONST_COSTS and will often depend on the constant value. In any
103 event, expressions containing constants can be simplified, by fold_rtx.
105 When a quantity has a known nearly constant value (such as an address
106 of a stack slot), that value is stored in the appropriate element
109 Integer constants don't have a machine mode. However, cse
110 determines the intended machine mode from the destination
111 of the instruction that moves the constant. The machine mode
112 is recorded in the hash table along with the actual RTL
113 constant expression so that different modes are kept separate.
117 To record known equivalences among expressions in general
118 we use a hash table called `table'. It has a fixed number of buckets
119 that contain chains of `struct table_elt' elements for expressions.
120 These chains connect the elements whose expressions have the same
123 Other chains through the same elements connect the elements which
124 currently have equivalent values.
126 Register references in an expression are canonicalized before hashing
127 the expression. This is done using `reg_qty' and `qty_first_reg'.
128 The hash code of a register reference is computed using the quantity
129 number, not the register number.
131 When the value of an expression changes, it is necessary to remove from the
132 hash table not just that expression but all expressions whose values
133 could be different as a result.
135 1. If the value changing is in memory, except in special cases
136 ANYTHING referring to memory could be changed. That is because
137 nobody knows where a pointer does not point.
138 The function `invalidate_memory' removes what is necessary.
140 The special cases are when the address is constant or is
141 a constant plus a fixed register such as the frame pointer
142 or a static chain pointer. When such addresses are stored in,
143 we can tell exactly which other such addresses must be invalidated
144 due to overlap. `invalidate' does this.
145 All expressions that refer to non-constant
146 memory addresses are also invalidated. `invalidate_memory' does this.
148 2. If the value changing is a register, all expressions
149 containing references to that register, and only those,
152 Because searching the entire hash table for expressions that contain
153 a register is very slow, we try to figure out when it isn't necessary.
154 Precisely, this is necessary only when expressions have been
155 entered in the hash table using this register, and then the value has
156 changed, and then another expression wants to be added to refer to
157 the register's new value. This sequence of circumstances is rare
158 within any one basic block.
160 The vectors `reg_tick' and `reg_in_table' are used to detect this case.
161 reg_tick[i] is incremented whenever a value is stored in register i.
162 reg_in_table[i] holds -1 if no references to register i have been
163 entered in the table; otherwise, it contains the value reg_tick[i] had
164 when the references were entered. If we want to enter a reference
165 and reg_in_table[i] != reg_tick[i], we must scan and remove old references.
166 Until we want to enter a new entry, the mere fact that the two vectors
167 don't match makes the entries be ignored if anyone tries to match them.
169 Registers themselves are entered in the hash table as well as in
170 the equivalent-register chains. However, the vectors `reg_tick'
171 and `reg_in_table' do not apply to expressions which are simple
172 register references. These expressions are removed from the table
173 immediately when they become invalid, and this can be done even if
174 we do not immediately search for all the expressions that refer to
177 A CLOBBER rtx in an instruction invalidates its operand for further
178 reuse. A CLOBBER or SET rtx whose operand is a MEM:BLK
179 invalidates everything that resides in memory.
183 Constant expressions that differ only by an additive integer
184 are called related. When a constant expression is put in
185 the table, the related expression with no constant term
186 is also entered. These are made to point at each other
187 so that it is possible to find out if there exists any
188 register equivalent to an expression related to a given expression. */
190 /* One plus largest register number used in this function. */
194 /* Length of vectors indexed by quantity number.
195 We know in advance we will not need a quantity number this big. */
199 /* Next quantity number to be allocated.
200 This is 1 + the largest number needed so far. */
204 /* Indexed by quantity number, gives the first (or last) (pseudo) register
205 in the chain of registers that currently contain this quantity. */
207 static int *qty_first_reg;
208 static int *qty_last_reg;
210 /* Index by quantity number, gives the mode of the quantity. */
212 static enum machine_mode *qty_mode;
214 /* Indexed by quantity number, gives the rtx of the constant value of the
215 quantity, or zero if it does not have a known value.
216 A sum of the frame pointer (or arg pointer) plus a constant
217 can also be entered here. */
219 static rtx *qty_const;
221 /* Indexed by qty number, gives the insn that stored the constant value
222 recorded in `qty_const'. */
224 static rtx *qty_const_insn;
226 /* The next three variables are used to track when a comparison between a
227 quantity and some constant or register has been passed. In that case, we
228 know the results of the comparison in case we see it again. These variables
229 record a comparison that is known to be true. */
231 /* Indexed by qty number, gives the rtx code of a comparison with a known
232 result involving this quantity. If none, it is UNKNOWN. */
233 static enum rtx_code *qty_comparison_code;
235 /* Indexed by qty number, gives the constant being compared against in a
236 comparison of known result. If no such comparison, it is undefined.
237 If the comparison is not with a constant, it is zero. */
239 static rtx *qty_comparison_const;
241 /* Indexed by qty number, gives the quantity being compared against in a
242 comparison of known result. If no such comparison, if it undefined.
243 If the comparison is not with a register, it is -1. */
245 static int *qty_comparison_qty;
248 /* For machines that have a CC0, we do not record its value in the hash
249 table since its use is guaranteed to be the insn immediately following
250 its definition and any other insn is presumed to invalidate it.
252 Instead, we store below the value last assigned to CC0. If it should
253 happen to be a constant, it is stored in preference to the actual
254 assigned value. In case it is a constant, we store the mode in which
255 the constant should be interpreted. */
257 static rtx prev_insn_cc0;
258 static enum machine_mode prev_insn_cc0_mode;
261 /* Previous actual insn. 0 if at first insn of basic block. */
263 static rtx prev_insn;
265 /* Insn being scanned. */
267 static rtx this_insn;
269 /* Index by (pseudo) register number, gives the quantity number
270 of the register's current contents. */
274 /* Index by (pseudo) register number, gives the number of the next (or
275 previous) (pseudo) register in the chain of registers sharing the same
278 Or -1 if this register is at the end of the chain.
280 If reg_qty[N] == N, reg_next_eqv[N] is undefined. */
282 static int *reg_next_eqv;
283 static int *reg_prev_eqv;
285 /* Index by (pseudo) register number, gives the number of times
286 that register has been altered in the current basic block. */
288 static int *reg_tick;
290 /* Index by (pseudo) register number, gives the reg_tick value at which
291 rtx's containing this register are valid in the hash table.
292 If this does not equal the current reg_tick value, such expressions
293 existing in the hash table are invalid.
294 If this is -1, no expressions containing this register have been
295 entered in the table. */
297 static int *reg_in_table;
299 /* A HARD_REG_SET containing all the hard registers for which there is
300 currently a REG expression in the hash table. Note the difference
301 from the above variables, which indicate if the REG is mentioned in some
302 expression in the table. */
304 static HARD_REG_SET hard_regs_in_table;
306 /* A HARD_REG_SET containing all the hard registers that are invalidated
309 static HARD_REG_SET regs_invalidated_by_call;
311 /* Two vectors of ints:
312 one containing max_reg -1's; the other max_reg + 500 (an approximation
313 for max_qty) elements where element i contains i.
314 These are used to initialize various other vectors fast. */
316 static int *all_minus_one;
317 static int *consec_ints;
319 /* CUID of insn that starts the basic block currently being cse-processed. */
321 static int cse_basic_block_start;
323 /* CUID of insn that ends the basic block currently being cse-processed. */
325 static int cse_basic_block_end;
327 /* Vector mapping INSN_UIDs to cuids.
328 The cuids are like uids but increase monotonically always.
329 We use them to see whether a reg is used outside a given basic block. */
331 static int *uid_cuid;
333 /* Highest UID in UID_CUID. */
336 /* Get the cuid of an insn. */
338 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
340 /* Nonzero if cse has altered conditional jump insns
341 in such a way that jump optimization should be redone. */
343 static int cse_jumps_altered;
345 /* canon_hash stores 1 in do_not_record
346 if it notices a reference to CC0, PC, or some other volatile
349 static int do_not_record;
351 #ifdef LOAD_EXTEND_OP
353 /* Scratch rtl used when looking for load-extended copy of a MEM. */
354 static rtx memory_extend_rtx;
357 /* canon_hash stores 1 in hash_arg_in_memory
358 if it notices a reference to memory within the expression being hashed. */
360 static int hash_arg_in_memory;
362 /* canon_hash stores 1 in hash_arg_in_struct
363 if it notices a reference to memory that's part of a structure. */
365 static int hash_arg_in_struct;
367 /* The hash table contains buckets which are chains of `struct table_elt's,
368 each recording one expression's information.
369 That expression is in the `exp' field.
371 Those elements with the same hash code are chained in both directions
372 through the `next_same_hash' and `prev_same_hash' fields.
374 Each set of expressions with equivalent values
375 are on a two-way chain through the `next_same_value'
376 and `prev_same_value' fields, and all point with
377 the `first_same_value' field at the first element in
378 that chain. The chain is in order of increasing cost.
379 Each element's cost value is in its `cost' field.
381 The `in_memory' field is nonzero for elements that
382 involve any reference to memory. These elements are removed
383 whenever a write is done to an unidentified location in memory.
384 To be safe, we assume that a memory address is unidentified unless
385 the address is either a symbol constant or a constant plus
386 the frame pointer or argument pointer.
388 The `in_struct' field is nonzero for elements that
389 involve any reference to memory inside a structure or array.
391 The `related_value' field is used to connect related expressions
392 (that differ by adding an integer).
393 The related expressions are chained in a circular fashion.
394 `related_value' is zero for expressions for which this
397 The `cost' field stores the cost of this element's expression.
399 The `is_const' flag is set if the element is a constant (including
402 The `flag' field is used as a temporary during some search routines.
404 The `mode' field is usually the same as GET_MODE (`exp'), but
405 if `exp' is a CONST_INT and has no machine mode then the `mode'
406 field is the mode it was being used as. Each constant is
407 recorded separately for each mode it is used with. */
413 struct table_elt *next_same_hash;
414 struct table_elt *prev_same_hash;
415 struct table_elt *next_same_value;
416 struct table_elt *prev_same_value;
417 struct table_elt *first_same_value;
418 struct table_elt *related_value;
420 enum machine_mode mode;
427 /* We don't want a lot of buckets, because we rarely have very many
428 things stored in the hash table, and a lot of buckets slows
429 down a lot of loops that happen frequently. */
432 /* Compute hash code of X in mode M. Special-case case where X is a pseudo
433 register (hard registers may require `do_not_record' to be set). */
436 (GET_CODE (X) == REG && REGNO (X) >= FIRST_PSEUDO_REGISTER \
437 ? (((unsigned) REG << 7) + (unsigned) reg_qty[REGNO (X)]) % NBUCKETS \
438 : canon_hash (X, M) % NBUCKETS)
440 /* Determine whether register number N is considered a fixed register for CSE.
441 It is desirable to replace other regs with fixed regs, to reduce need for
443 A reg wins if it is either the frame pointer or designated as fixed,
444 but not if it is an overlapping register. */
445 #ifdef OVERLAPPING_REGNO_P
446 #define FIXED_REGNO_P(N) \
447 (((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \
448 || fixed_regs[N] || global_regs[N]) \
449 && ! OVERLAPPING_REGNO_P ((N)))
451 #define FIXED_REGNO_P(N) \
452 ((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \
453 || fixed_regs[N] || global_regs[N])
456 /* Compute cost of X, as stored in the `cost' field of a table_elt. Fixed
457 hard registers and pointers into the frame are the cheapest with a cost
458 of 0. Next come pseudos with a cost of one and other hard registers with
459 a cost of 2. Aside from these special cases, call `rtx_cost'. */
461 #define CHEAP_REGNO(N) \
462 ((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \
463 || (N) == STACK_POINTER_REGNUM || (N) == ARG_POINTER_REGNUM \
464 || ((N) >= FIRST_VIRTUAL_REGISTER && (N) <= LAST_VIRTUAL_REGISTER) \
465 || ((N) < FIRST_PSEUDO_REGISTER \
466 && FIXED_REGNO_P (N) && REGNO_REG_CLASS (N) != NO_REGS))
468 /* A register is cheap if it is a user variable assigned to the register
469 or if its register number always corresponds to a cheap register. */
471 #define CHEAP_REG(N) \
472 ((REG_USERVAR_P (N) && REGNO (N) < FIRST_PSEUDO_REGISTER) \
473 || CHEAP_REGNO (REGNO (N)))
476 (GET_CODE (X) == REG \
477 ? (CHEAP_REG (X) ? 0 \
478 : REGNO (X) >= FIRST_PSEUDO_REGISTER ? 1 \
480 : rtx_cost (X, SET) * 2)
482 /* Determine if the quantity number for register X represents a valid index
483 into the `qty_...' variables. */
485 #define REGNO_QTY_VALID_P(N) (reg_qty[N] != (N))
487 static struct table_elt *table[NBUCKETS];
489 /* Chain of `struct table_elt's made so far for this function
490 but currently removed from the table. */
492 static struct table_elt *free_element_chain;
494 /* Number of `struct table_elt' structures made so far for this function. */
496 static int n_elements_made;
498 /* Maximum value `n_elements_made' has had so far in this compilation
499 for functions previously processed. */
501 static int max_elements_made;
503 /* Surviving equivalence class when two equivalence classes are merged
504 by recording the effects of a jump in the last insn. Zero if the
505 last insn was not a conditional jump. */
507 static struct table_elt *last_jump_equiv_class;
509 /* Set to the cost of a constant pool reference if one was found for a
510 symbolic constant. If this was found, it means we should try to
511 convert constants into constant pool entries if they don't fit in
514 static int constant_pool_entries_cost;
516 /* Bits describing what kind of values in memory must be invalidated
517 for a particular instruction. If all three bits are zero,
518 no memory refs need to be invalidated. Each bit is more powerful
519 than the preceding ones, and if a bit is set then the preceding
522 Here is how the bits are set:
523 Pushing onto the stack invalidates only the stack pointer,
524 writing at a fixed address invalidates only variable addresses,
525 writing in a structure element at variable address
526 invalidates all but scalar variables,
527 and writing in anything else at variable address invalidates everything. */
531 int sp : 1; /* Invalidate stack pointer. */
532 int var : 1; /* Invalidate variable addresses. */
533 int nonscalar : 1; /* Invalidate all but scalar variables. */
534 int all : 1; /* Invalidate all memory refs. */
537 /* Define maximum length of a branch path. */
539 #define PATHLENGTH 10
541 /* This data describes a block that will be processed by cse_basic_block. */
543 struct cse_basic_block_data {
544 /* Lowest CUID value of insns in block. */
546 /* Highest CUID value of insns in block. */
548 /* Total number of SETs in block. */
550 /* Last insn in the block. */
552 /* Size of current branch path, if any. */
554 /* Current branch path, indicating which branches will be taken. */
556 /* The branch insn. */
558 /* Whether it should be taken or not. AROUND is the same as taken
559 except that it is used when the destination label is not preceded
561 enum taken {TAKEN, NOT_TAKEN, AROUND} status;
565 /* Nonzero if X has the form (PLUS frame-pointer integer). We check for
566 virtual regs here because the simplify_*_operation routines are called
567 by integrate.c, which is called before virtual register instantiation. */
569 #define FIXED_BASE_PLUS_P(X) \
570 ((X) == frame_pointer_rtx || (X) == hard_frame_pointer_rtx \
571 || (X) == arg_pointer_rtx \
572 || (X) == virtual_stack_vars_rtx \
573 || (X) == virtual_incoming_args_rtx \
574 || (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \
575 && (XEXP (X, 0) == frame_pointer_rtx \
576 || XEXP (X, 0) == hard_frame_pointer_rtx \
577 || XEXP (X, 0) == arg_pointer_rtx \
578 || XEXP (X, 0) == virtual_stack_vars_rtx \
579 || XEXP (X, 0) == virtual_incoming_args_rtx)))
581 /* Similar, but also allows reference to the stack pointer.
583 This used to include FIXED_BASE_PLUS_P, however, we can't assume that
584 arg_pointer_rtx by itself is nonzero, because on at least one machine,
585 the i960, the arg pointer is zero when it is unused. */
587 #define NONZERO_BASE_PLUS_P(X) \
588 ((X) == frame_pointer_rtx || (X) == hard_frame_pointer_rtx \
589 || (X) == virtual_stack_vars_rtx \
590 || (X) == virtual_incoming_args_rtx \
591 || (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \
592 && (XEXP (X, 0) == frame_pointer_rtx \
593 || XEXP (X, 0) == hard_frame_pointer_rtx \
594 || XEXP (X, 0) == arg_pointer_rtx \
595 || XEXP (X, 0) == virtual_stack_vars_rtx \
596 || XEXP (X, 0) == virtual_incoming_args_rtx)) \
597 || (X) == stack_pointer_rtx \
598 || (X) == virtual_stack_dynamic_rtx \
599 || (X) == virtual_outgoing_args_rtx \
600 || (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \
601 && (XEXP (X, 0) == stack_pointer_rtx \
602 || XEXP (X, 0) == virtual_stack_dynamic_rtx \
603 || XEXP (X, 0) == virtual_outgoing_args_rtx)))
605 static void new_basic_block PROTO((void));
606 static void make_new_qty PROTO((int));
607 static void make_regs_eqv PROTO((int, int));
608 static void delete_reg_equiv PROTO((int));
609 static int mention_regs PROTO((rtx));
610 static int insert_regs PROTO((rtx, struct table_elt *, int));
611 static void free_element PROTO((struct table_elt *));
612 static void remove_from_table PROTO((struct table_elt *, unsigned));
613 static struct table_elt *get_element PROTO((void));
614 static struct table_elt *lookup PROTO((rtx, unsigned, enum machine_mode)),
615 *lookup_for_remove PROTO((rtx, unsigned, enum machine_mode));
616 static rtx lookup_as_function PROTO((rtx, enum rtx_code));
617 static struct table_elt *insert PROTO((rtx, struct table_elt *, unsigned,
619 static void merge_equiv_classes PROTO((struct table_elt *,
620 struct table_elt *));
621 static void invalidate PROTO((rtx, enum machine_mode));
622 static void remove_invalid_refs PROTO((int));
623 static void rehash_using_reg PROTO((rtx));
624 static void invalidate_memory PROTO((struct write_data *));
625 static void invalidate_for_call PROTO((void));
626 static rtx use_related_value PROTO((rtx, struct table_elt *));
627 static unsigned canon_hash PROTO((rtx, enum machine_mode));
628 static unsigned safe_hash PROTO((rtx, enum machine_mode));
629 static int exp_equiv_p PROTO((rtx, rtx, int, int));
630 static void set_nonvarying_address_components PROTO((rtx, int, rtx *,
633 static int refers_to_p PROTO((rtx, rtx));
634 static int refers_to_mem_p PROTO((rtx, rtx, HOST_WIDE_INT,
636 static int cse_rtx_addr_varies_p PROTO((rtx));
637 static rtx canon_reg PROTO((rtx, rtx));
638 static void find_best_addr PROTO((rtx, rtx *));
639 static enum rtx_code find_comparison_args PROTO((enum rtx_code, rtx *, rtx *,
641 enum machine_mode *));
642 static rtx cse_gen_binary PROTO((enum rtx_code, enum machine_mode,
644 static rtx simplify_plus_minus PROTO((enum rtx_code, enum machine_mode,
646 static rtx fold_rtx PROTO((rtx, rtx));
647 static rtx equiv_constant PROTO((rtx));
648 static void record_jump_equiv PROTO((rtx, int));
649 static void record_jump_cond PROTO((enum rtx_code, enum machine_mode,
651 static void cse_insn PROTO((rtx, int));
652 static void note_mem_written PROTO((rtx, struct write_data *));
653 static void invalidate_from_clobbers PROTO((struct write_data *, rtx));
654 static rtx cse_process_notes PROTO((rtx, rtx));
655 static void cse_around_loop PROTO((rtx));
656 static void invalidate_skipped_set PROTO((rtx, rtx));
657 static void invalidate_skipped_block PROTO((rtx));
658 static void cse_check_loop_start PROTO((rtx, rtx));
659 static void cse_set_around_loop PROTO((rtx, rtx, rtx));
660 static rtx cse_basic_block PROTO((rtx, rtx, struct branch_path *, int));
661 static void count_reg_usage PROTO((rtx, int *, rtx, int));
663 extern int rtx_equal_function_value_matters;
665 /* Return an estimate of the cost of computing rtx X.
666 One use is in cse, to decide which expression to keep in the hash table.
667 Another is in rtl generation, to pick the cheapest way to multiply.
668 Other uses like the latter are expected in the future. */
670 /* Return the right cost to give to an operation
671 to make the cost of the corresponding register-to-register instruction
672 N times that of a fast register-to-register instruction. */
674 #define COSTS_N_INSNS(N) ((N) * 4 - 2)
677 rtx_cost (x, outer_code)
679 enum rtx_code outer_code;
682 register enum rtx_code code;
689 /* Compute the default costs of certain things.
690 Note that RTX_COSTS can override the defaults. */
696 /* Count multiplication by 2**n as a shift,
697 because if we are considering it, we would output it as a shift. */
698 if (GET_CODE (XEXP (x, 1)) == CONST_INT
699 && exact_log2 (INTVAL (XEXP (x, 1))) >= 0)
702 total = COSTS_N_INSNS (5);
708 total = COSTS_N_INSNS (7);
711 /* Used in loop.c and combine.c as a marker. */
715 /* We don't want these to be used in substitutions because
716 we have no way of validating the resulting insn. So assign
717 anything containing an ASM_OPERANDS a very high cost. */
727 return ! CHEAP_REG (x);
730 /* If we can't tie these modes, make this expensive. The larger
731 the mode, the more expensive it is. */
732 if (! MODES_TIEABLE_P (GET_MODE (x), GET_MODE (SUBREG_REG (x))))
733 return COSTS_N_INSNS (2
734 + GET_MODE_SIZE (GET_MODE (x)) / UNITS_PER_WORD);
737 RTX_COSTS (x, code, outer_code);
739 CONST_COSTS (x, code, outer_code);
742 /* Sum the costs of the sub-rtx's, plus cost of this operation,
743 which is already in total. */
745 fmt = GET_RTX_FORMAT (code);
746 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
748 total += rtx_cost (XEXP (x, i), code);
749 else if (fmt[i] == 'E')
750 for (j = 0; j < XVECLEN (x, i); j++)
751 total += rtx_cost (XVECEXP (x, i, j), code);
756 /* Clear the hash table and initialize each register with its own quantity,
757 for a new basic block. */
766 bzero ((char *) reg_tick, max_reg * sizeof (int));
768 bcopy ((char *) all_minus_one, (char *) reg_in_table,
769 max_reg * sizeof (int));
770 bcopy ((char *) consec_ints, (char *) reg_qty, max_reg * sizeof (int));
771 CLEAR_HARD_REG_SET (hard_regs_in_table);
773 /* The per-quantity values used to be initialized here, but it is
774 much faster to initialize each as it is made in `make_new_qty'. */
776 for (i = 0; i < NBUCKETS; i++)
778 register struct table_elt *this, *next;
779 for (this = table[i]; this; this = next)
781 next = this->next_same_hash;
786 bzero ((char *) table, sizeof table);
795 /* Say that register REG contains a quantity not in any register before
796 and initialize that quantity. */
804 if (next_qty >= max_qty)
807 q = reg_qty[reg] = next_qty++;
808 qty_first_reg[q] = reg;
809 qty_last_reg[q] = reg;
810 qty_const[q] = qty_const_insn[q] = 0;
811 qty_comparison_code[q] = UNKNOWN;
813 reg_next_eqv[reg] = reg_prev_eqv[reg] = -1;
816 /* Make reg NEW equivalent to reg OLD.
817 OLD is not changing; NEW is. */
820 make_regs_eqv (new, old)
821 register int new, old;
823 register int lastr, firstr;
824 register int q = reg_qty[old];
826 /* Nothing should become eqv until it has a "non-invalid" qty number. */
827 if (! REGNO_QTY_VALID_P (old))
831 firstr = qty_first_reg[q];
832 lastr = qty_last_reg[q];
834 /* Prefer fixed hard registers to anything. Prefer pseudo regs to other
835 hard regs. Among pseudos, if NEW will live longer than any other reg
836 of the same qty, and that is beyond the current basic block,
837 make it the new canonical replacement for this qty. */
838 if (! (firstr < FIRST_PSEUDO_REGISTER && FIXED_REGNO_P (firstr))
839 /* Certain fixed registers might be of the class NO_REGS. This means
840 that not only can they not be allocated by the compiler, but
841 they cannot be used in substitutions or canonicalizations
843 && (new >= FIRST_PSEUDO_REGISTER || REGNO_REG_CLASS (new) != NO_REGS)
844 && ((new < FIRST_PSEUDO_REGISTER && FIXED_REGNO_P (new))
845 || (new >= FIRST_PSEUDO_REGISTER
846 && (firstr < FIRST_PSEUDO_REGISTER
847 || ((uid_cuid[regno_last_uid[new]] > cse_basic_block_end
848 || (uid_cuid[regno_first_uid[new]]
849 < cse_basic_block_start))
850 && (uid_cuid[regno_last_uid[new]]
851 > uid_cuid[regno_last_uid[firstr]]))))))
853 reg_prev_eqv[firstr] = new;
854 reg_next_eqv[new] = firstr;
855 reg_prev_eqv[new] = -1;
856 qty_first_reg[q] = new;
860 /* If NEW is a hard reg (known to be non-fixed), insert at end.
861 Otherwise, insert before any non-fixed hard regs that are at the
862 end. Registers of class NO_REGS cannot be used as an
863 equivalent for anything. */
864 while (lastr < FIRST_PSEUDO_REGISTER && reg_prev_eqv[lastr] >= 0
865 && (REGNO_REG_CLASS (lastr) == NO_REGS || ! FIXED_REGNO_P (lastr))
866 && new >= FIRST_PSEUDO_REGISTER)
867 lastr = reg_prev_eqv[lastr];
868 reg_next_eqv[new] = reg_next_eqv[lastr];
869 if (reg_next_eqv[lastr] >= 0)
870 reg_prev_eqv[reg_next_eqv[lastr]] = new;
872 qty_last_reg[q] = new;
873 reg_next_eqv[lastr] = new;
874 reg_prev_eqv[new] = lastr;
878 /* Remove REG from its equivalence class. */
881 delete_reg_equiv (reg)
884 register int q = reg_qty[reg];
887 /* If invalid, do nothing. */
891 p = reg_prev_eqv[reg];
892 n = reg_next_eqv[reg];
901 qty_first_reg[q] = n;
906 /* Remove any invalid expressions from the hash table
907 that refer to any of the registers contained in expression X.
909 Make sure that newly inserted references to those registers
910 as subexpressions will be considered valid.
912 mention_regs is not called when a register itself
913 is being stored in the table.
915 Return 1 if we have done something that may have changed the hash code
922 register enum rtx_code code;
925 register int changed = 0;
933 register int regno = REGNO (x);
934 register int endregno
935 = regno + (regno >= FIRST_PSEUDO_REGISTER ? 1
936 : HARD_REGNO_NREGS (regno, GET_MODE (x)));
939 for (i = regno; i < endregno; i++)
941 if (reg_in_table[i] >= 0 && reg_in_table[i] != reg_tick[i])
942 remove_invalid_refs (i);
944 reg_in_table[i] = reg_tick[i];
950 /* If X is a comparison or a COMPARE and either operand is a register
951 that does not have a quantity, give it one. This is so that a later
952 call to record_jump_equiv won't cause X to be assigned a different
953 hash code and not found in the table after that call.
955 It is not necessary to do this here, since rehash_using_reg can
956 fix up the table later, but doing this here eliminates the need to
957 call that expensive function in the most common case where the only
958 use of the register is in the comparison. */
960 if (code == COMPARE || GET_RTX_CLASS (code) == '<')
962 if (GET_CODE (XEXP (x, 0)) == REG
963 && ! REGNO_QTY_VALID_P (REGNO (XEXP (x, 0))))
964 if (insert_regs (XEXP (x, 0), NULL_PTR, 0))
966 rehash_using_reg (XEXP (x, 0));
970 if (GET_CODE (XEXP (x, 1)) == REG
971 && ! REGNO_QTY_VALID_P (REGNO (XEXP (x, 1))))
972 if (insert_regs (XEXP (x, 1), NULL_PTR, 0))
974 rehash_using_reg (XEXP (x, 1));
979 fmt = GET_RTX_FORMAT (code);
980 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
982 changed |= mention_regs (XEXP (x, i));
983 else if (fmt[i] == 'E')
984 for (j = 0; j < XVECLEN (x, i); j++)
985 changed |= mention_regs (XVECEXP (x, i, j));
990 /* Update the register quantities for inserting X into the hash table
991 with a value equivalent to CLASSP.
992 (If the class does not contain a REG, it is irrelevant.)
993 If MODIFIED is nonzero, X is a destination; it is being modified.
994 Note that delete_reg_equiv should be called on a register
995 before insert_regs is done on that register with MODIFIED != 0.
997 Nonzero value means that elements of reg_qty have changed
998 so X's hash code may be different. */
1001 insert_regs (x, classp, modified)
1003 struct table_elt *classp;
1006 if (GET_CODE (x) == REG)
1008 register int regno = REGNO (x);
1010 /* If REGNO is in the equivalence table already but is of the
1011 wrong mode for that equivalence, don't do anything here. */
1013 if (REGNO_QTY_VALID_P (regno)
1014 && qty_mode[reg_qty[regno]] != GET_MODE (x))
1017 if (modified || ! REGNO_QTY_VALID_P (regno))
1020 for (classp = classp->first_same_value;
1022 classp = classp->next_same_value)
1023 if (GET_CODE (classp->exp) == REG
1024 && GET_MODE (classp->exp) == GET_MODE (x))
1026 make_regs_eqv (regno, REGNO (classp->exp));
1030 make_new_qty (regno);
1031 qty_mode[reg_qty[regno]] = GET_MODE (x);
1038 /* If X is a SUBREG, we will likely be inserting the inner register in the
1039 table. If that register doesn't have an assigned quantity number at
1040 this point but does later, the insertion that we will be doing now will
1041 not be accessible because its hash code will have changed. So assign
1042 a quantity number now. */
1044 else if (GET_CODE (x) == SUBREG && GET_CODE (SUBREG_REG (x)) == REG
1045 && ! REGNO_QTY_VALID_P (REGNO (SUBREG_REG (x))))
1047 insert_regs (SUBREG_REG (x), NULL_PTR, 0);
1048 mention_regs (SUBREG_REG (x));
1052 return mention_regs (x);
1055 /* Look in or update the hash table. */
1057 /* Put the element ELT on the list of free elements. */
1061 struct table_elt *elt;
1063 elt->next_same_hash = free_element_chain;
1064 free_element_chain = elt;
1067 /* Return an element that is free for use. */
1069 static struct table_elt *
1072 struct table_elt *elt = free_element_chain;
1075 free_element_chain = elt->next_same_hash;
1079 return (struct table_elt *) oballoc (sizeof (struct table_elt));
1082 /* Remove table element ELT from use in the table.
1083 HASH is its hash code, made using the HASH macro.
1084 It's an argument because often that is known in advance
1085 and we save much time not recomputing it. */
1088 remove_from_table (elt, hash)
1089 register struct table_elt *elt;
1095 /* Mark this element as removed. See cse_insn. */
1096 elt->first_same_value = 0;
1098 /* Remove the table element from its equivalence class. */
1101 register struct table_elt *prev = elt->prev_same_value;
1102 register struct table_elt *next = elt->next_same_value;
1104 if (next) next->prev_same_value = prev;
1107 prev->next_same_value = next;
1110 register struct table_elt *newfirst = next;
1113 next->first_same_value = newfirst;
1114 next = next->next_same_value;
1119 /* Remove the table element from its hash bucket. */
1122 register struct table_elt *prev = elt->prev_same_hash;
1123 register struct table_elt *next = elt->next_same_hash;
1125 if (next) next->prev_same_hash = prev;
1128 prev->next_same_hash = next;
1129 else if (table[hash] == elt)
1133 /* This entry is not in the proper hash bucket. This can happen
1134 when two classes were merged by `merge_equiv_classes'. Search
1135 for the hash bucket that it heads. This happens only very
1136 rarely, so the cost is acceptable. */
1137 for (hash = 0; hash < NBUCKETS; hash++)
1138 if (table[hash] == elt)
1143 /* Remove the table element from its related-value circular chain. */
1145 if (elt->related_value != 0 && elt->related_value != elt)
1147 register struct table_elt *p = elt->related_value;
1148 while (p->related_value != elt)
1149 p = p->related_value;
1150 p->related_value = elt->related_value;
1151 if (p->related_value == p)
1152 p->related_value = 0;
1158 /* Look up X in the hash table and return its table element,
1159 or 0 if X is not in the table.
1161 MODE is the machine-mode of X, or if X is an integer constant
1162 with VOIDmode then MODE is the mode with which X will be used.
1164 Here we are satisfied to find an expression whose tree structure
1167 static struct table_elt *
1168 lookup (x, hash, mode)
1171 enum machine_mode mode;
1173 register struct table_elt *p;
1175 for (p = table[hash]; p; p = p->next_same_hash)
1176 if (mode == p->mode && ((x == p->exp && GET_CODE (x) == REG)
1177 || exp_equiv_p (x, p->exp, GET_CODE (x) != REG, 0)))
1183 /* Like `lookup' but don't care whether the table element uses invalid regs.
1184 Also ignore discrepancies in the machine mode of a register. */
1186 static struct table_elt *
1187 lookup_for_remove (x, hash, mode)
1190 enum machine_mode mode;
1192 register struct table_elt *p;
1194 if (GET_CODE (x) == REG)
1196 int regno = REGNO (x);
1197 /* Don't check the machine mode when comparing registers;
1198 invalidating (REG:SI 0) also invalidates (REG:DF 0). */
1199 for (p = table[hash]; p; p = p->next_same_hash)
1200 if (GET_CODE (p->exp) == REG
1201 && REGNO (p->exp) == regno)
1206 for (p = table[hash]; p; p = p->next_same_hash)
1207 if (mode == p->mode && (x == p->exp || exp_equiv_p (x, p->exp, 0, 0)))
1214 /* Look for an expression equivalent to X and with code CODE.
1215 If one is found, return that expression. */
1218 lookup_as_function (x, code)
1222 register struct table_elt *p = lookup (x, safe_hash (x, VOIDmode) % NBUCKETS,
1227 for (p = p->first_same_value; p; p = p->next_same_value)
1229 if (GET_CODE (p->exp) == code
1230 /* Make sure this is a valid entry in the table. */
1231 && exp_equiv_p (p->exp, p->exp, 1, 0))
1238 /* Insert X in the hash table, assuming HASH is its hash code
1239 and CLASSP is an element of the class it should go in
1240 (or 0 if a new class should be made).
1241 It is inserted at the proper position to keep the class in
1242 the order cheapest first.
1244 MODE is the machine-mode of X, or if X is an integer constant
1245 with VOIDmode then MODE is the mode with which X will be used.
1247 For elements of equal cheapness, the most recent one
1248 goes in front, except that the first element in the list
1249 remains first unless a cheaper element is added. The order of
1250 pseudo-registers does not matter, as canon_reg will be called to
1251 find the cheapest when a register is retrieved from the table.
1253 The in_memory field in the hash table element is set to 0.
1254 The caller must set it nonzero if appropriate.
1256 You should call insert_regs (X, CLASSP, MODIFY) before calling here,
1257 and if insert_regs returns a nonzero value
1258 you must then recompute its hash code before calling here.
1260 If necessary, update table showing constant values of quantities. */
1262 #define CHEAPER(X,Y) ((X)->cost < (Y)->cost)
1264 static struct table_elt *
1265 insert (x, classp, hash, mode)
1267 register struct table_elt *classp;
1269 enum machine_mode mode;
1271 register struct table_elt *elt;
1273 /* If X is a register and we haven't made a quantity for it,
1274 something is wrong. */
1275 if (GET_CODE (x) == REG && ! REGNO_QTY_VALID_P (REGNO (x)))
1278 /* If X is a hard register, show it is being put in the table. */
1279 if (GET_CODE (x) == REG && REGNO (x) < FIRST_PSEUDO_REGISTER)
1281 int regno = REGNO (x);
1282 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
1285 for (i = regno; i < endregno; i++)
1286 SET_HARD_REG_BIT (hard_regs_in_table, i);
1290 /* Put an element for X into the right hash bucket. */
1292 elt = get_element ();
1294 elt->cost = COST (x);
1295 elt->next_same_value = 0;
1296 elt->prev_same_value = 0;
1297 elt->next_same_hash = table[hash];
1298 elt->prev_same_hash = 0;
1299 elt->related_value = 0;
1302 elt->is_const = (CONSTANT_P (x)
1303 /* GNU C++ takes advantage of this for `this'
1304 (and other const values). */
1305 || (RTX_UNCHANGING_P (x)
1306 && GET_CODE (x) == REG
1307 && REGNO (x) >= FIRST_PSEUDO_REGISTER)
1308 || FIXED_BASE_PLUS_P (x));
1311 table[hash]->prev_same_hash = elt;
1314 /* Put it into the proper value-class. */
1317 classp = classp->first_same_value;
1318 if (CHEAPER (elt, classp))
1319 /* Insert at the head of the class */
1321 register struct table_elt *p;
1322 elt->next_same_value = classp;
1323 classp->prev_same_value = elt;
1324 elt->first_same_value = elt;
1326 for (p = classp; p; p = p->next_same_value)
1327 p->first_same_value = elt;
1331 /* Insert not at head of the class. */
1332 /* Put it after the last element cheaper than X. */
1333 register struct table_elt *p, *next;
1334 for (p = classp; (next = p->next_same_value) && CHEAPER (next, elt);
1336 /* Put it after P and before NEXT. */
1337 elt->next_same_value = next;
1339 next->prev_same_value = elt;
1340 elt->prev_same_value = p;
1341 p->next_same_value = elt;
1342 elt->first_same_value = classp;
1346 elt->first_same_value = elt;
1348 /* If this is a constant being set equivalent to a register or a register
1349 being set equivalent to a constant, note the constant equivalence.
1351 If this is a constant, it cannot be equivalent to a different constant,
1352 and a constant is the only thing that can be cheaper than a register. So
1353 we know the register is the head of the class (before the constant was
1356 If this is a register that is not already known equivalent to a
1357 constant, we must check the entire class.
1359 If this is a register that is already known equivalent to an insn,
1360 update `qty_const_insn' to show that `this_insn' is the latest
1361 insn making that quantity equivalent to the constant. */
1363 if (elt->is_const && classp && GET_CODE (classp->exp) == REG)
1365 qty_const[reg_qty[REGNO (classp->exp)]]
1366 = gen_lowpart_if_possible (qty_mode[reg_qty[REGNO (classp->exp)]], x);
1367 qty_const_insn[reg_qty[REGNO (classp->exp)]] = this_insn;
1370 else if (GET_CODE (x) == REG && classp && ! qty_const[reg_qty[REGNO (x)]])
1372 register struct table_elt *p;
1374 for (p = classp; p != 0; p = p->next_same_value)
1378 qty_const[reg_qty[REGNO (x)]]
1379 = gen_lowpart_if_possible (GET_MODE (x), p->exp);
1380 qty_const_insn[reg_qty[REGNO (x)]] = this_insn;
1386 else if (GET_CODE (x) == REG && qty_const[reg_qty[REGNO (x)]]
1387 && GET_MODE (x) == qty_mode[reg_qty[REGNO (x)]])
1388 qty_const_insn[reg_qty[REGNO (x)]] = this_insn;
1390 /* If this is a constant with symbolic value,
1391 and it has a term with an explicit integer value,
1392 link it up with related expressions. */
1393 if (GET_CODE (x) == CONST)
1395 rtx subexp = get_related_value (x);
1397 struct table_elt *subelt, *subelt_prev;
1401 /* Get the integer-free subexpression in the hash table. */
1402 subhash = safe_hash (subexp, mode) % NBUCKETS;
1403 subelt = lookup (subexp, subhash, mode);
1405 subelt = insert (subexp, NULL_PTR, subhash, mode);
1406 /* Initialize SUBELT's circular chain if it has none. */
1407 if (subelt->related_value == 0)
1408 subelt->related_value = subelt;
1409 /* Find the element in the circular chain that precedes SUBELT. */
1410 subelt_prev = subelt;
1411 while (subelt_prev->related_value != subelt)
1412 subelt_prev = subelt_prev->related_value;
1413 /* Put new ELT into SUBELT's circular chain just before SUBELT.
1414 This way the element that follows SUBELT is the oldest one. */
1415 elt->related_value = subelt_prev->related_value;
1416 subelt_prev->related_value = elt;
1423 /* Given two equivalence classes, CLASS1 and CLASS2, put all the entries from
1424 CLASS2 into CLASS1. This is done when we have reached an insn which makes
1425 the two classes equivalent.
1427 CLASS1 will be the surviving class; CLASS2 should not be used after this
1430 Any invalid entries in CLASS2 will not be copied. */
1433 merge_equiv_classes (class1, class2)
1434 struct table_elt *class1, *class2;
1436 struct table_elt *elt, *next, *new;
1438 /* Ensure we start with the head of the classes. */
1439 class1 = class1->first_same_value;
1440 class2 = class2->first_same_value;
1442 /* If they were already equal, forget it. */
1443 if (class1 == class2)
1446 for (elt = class2; elt; elt = next)
1450 enum machine_mode mode = elt->mode;
1452 next = elt->next_same_value;
1454 /* Remove old entry, make a new one in CLASS1's class.
1455 Don't do this for invalid entries as we cannot find their
1456 hash code (it also isn't necessary). */
1457 if (GET_CODE (exp) == REG || exp_equiv_p (exp, exp, 1, 0))
1459 hash_arg_in_memory = 0;
1460 hash_arg_in_struct = 0;
1461 hash = HASH (exp, mode);
1463 if (GET_CODE (exp) == REG)
1464 delete_reg_equiv (REGNO (exp));
1466 remove_from_table (elt, hash);
1468 if (insert_regs (exp, class1, 0))
1469 hash = HASH (exp, mode);
1470 new = insert (exp, class1, hash, mode);
1471 new->in_memory = hash_arg_in_memory;
1472 new->in_struct = hash_arg_in_struct;
1477 /* Remove from the hash table, or mark as invalid,
1478 all expressions whose values could be altered by storing in X.
1479 X is a register, a subreg, or a memory reference with nonvarying address
1480 (because, when a memory reference with a varying address is stored in,
1481 all memory references are removed by invalidate_memory
1482 so specific invalidation is superfluous).
1483 FULL_MODE, if not VOIDmode, indicates that this much should be invalidated
1484 instead of just the amount indicated by the mode of X. This is only used
1485 for bitfield stores into memory.
1487 A nonvarying address may be just a register or just
1488 a symbol reference, or it may be either of those plus
1489 a numeric offset. */
1492 invalidate (x, full_mode)
1494 enum machine_mode full_mode;
1497 register struct table_elt *p;
1499 HOST_WIDE_INT start, end;
1501 /* If X is a register, dependencies on its contents
1502 are recorded through the qty number mechanism.
1503 Just change the qty number of the register,
1504 mark it as invalid for expressions that refer to it,
1505 and remove it itself. */
1507 if (GET_CODE (x) == REG)
1509 register int regno = REGNO (x);
1510 register unsigned hash = HASH (x, GET_MODE (x));
1512 /* Remove REGNO from any quantity list it might be on and indicate
1513 that it's value might have changed. If it is a pseudo, remove its
1514 entry from the hash table.
1516 For a hard register, we do the first two actions above for any
1517 additional hard registers corresponding to X. Then, if any of these
1518 registers are in the table, we must remove any REG entries that
1519 overlap these registers. */
1521 delete_reg_equiv (regno);
1524 if (regno >= FIRST_PSEUDO_REGISTER)
1525 remove_from_table (lookup_for_remove (x, hash, GET_MODE (x)), hash);
1528 HOST_WIDE_INT in_table
1529 = TEST_HARD_REG_BIT (hard_regs_in_table, regno);
1530 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
1531 int tregno, tendregno;
1532 register struct table_elt *p, *next;
1534 CLEAR_HARD_REG_BIT (hard_regs_in_table, regno);
1536 for (i = regno + 1; i < endregno; i++)
1538 in_table |= TEST_HARD_REG_BIT (hard_regs_in_table, i);
1539 CLEAR_HARD_REG_BIT (hard_regs_in_table, i);
1540 delete_reg_equiv (i);
1545 for (hash = 0; hash < NBUCKETS; hash++)
1546 for (p = table[hash]; p; p = next)
1548 next = p->next_same_hash;
1550 if (GET_CODE (p->exp) != REG
1551 || REGNO (p->exp) >= FIRST_PSEUDO_REGISTER)
1554 tregno = REGNO (p->exp);
1556 = tregno + HARD_REGNO_NREGS (tregno, GET_MODE (p->exp));
1557 if (tendregno > regno && tregno < endregno)
1558 remove_from_table (p, hash);
1565 if (GET_CODE (x) == SUBREG)
1567 if (GET_CODE (SUBREG_REG (x)) != REG)
1569 invalidate (SUBREG_REG (x), VOIDmode);
1573 /* X is not a register; it must be a memory reference with
1574 a nonvarying address. Remove all hash table elements
1575 that refer to overlapping pieces of memory. */
1577 if (GET_CODE (x) != MEM)
1580 if (full_mode == VOIDmode)
1581 full_mode = GET_MODE (x);
1583 set_nonvarying_address_components (XEXP (x, 0), GET_MODE_SIZE (full_mode),
1584 &base, &start, &end);
1586 for (i = 0; i < NBUCKETS; i++)
1588 register struct table_elt *next;
1589 for (p = table[i]; p; p = next)
1591 next = p->next_same_hash;
1592 if (refers_to_mem_p (p->exp, base, start, end))
1593 remove_from_table (p, i);
1598 /* Remove all expressions that refer to register REGNO,
1599 since they are already invalid, and we are about to
1600 mark that register valid again and don't want the old
1601 expressions to reappear as valid. */
1604 remove_invalid_refs (regno)
1608 register struct table_elt *p, *next;
1610 for (i = 0; i < NBUCKETS; i++)
1611 for (p = table[i]; p; p = next)
1613 next = p->next_same_hash;
1614 if (GET_CODE (p->exp) != REG
1615 && refers_to_regno_p (regno, regno + 1, p->exp, NULL_PTR))
1616 remove_from_table (p, i);
1620 /* Recompute the hash codes of any valid entries in the hash table that
1621 reference X, if X is a register, or SUBREG_REG (X) if X is a SUBREG.
1623 This is called when we make a jump equivalence. */
1626 rehash_using_reg (x)
1630 struct table_elt *p, *next;
1633 if (GET_CODE (x) == SUBREG)
1636 /* If X is not a register or if the register is known not to be in any
1637 valid entries in the table, we have no work to do. */
1639 if (GET_CODE (x) != REG
1640 || reg_in_table[REGNO (x)] < 0
1641 || reg_in_table[REGNO (x)] != reg_tick[REGNO (x)])
1644 /* Scan all hash chains looking for valid entries that mention X.
1645 If we find one and it is in the wrong hash chain, move it. We can skip
1646 objects that are registers, since they are handled specially. */
1648 for (i = 0; i < NBUCKETS; i++)
1649 for (p = table[i]; p; p = next)
1651 next = p->next_same_hash;
1652 if (GET_CODE (p->exp) != REG && reg_mentioned_p (x, p->exp)
1653 && exp_equiv_p (p->exp, p->exp, 1, 0)
1654 && i != (hash = safe_hash (p->exp, p->mode) % NBUCKETS))
1656 if (p->next_same_hash)
1657 p->next_same_hash->prev_same_hash = p->prev_same_hash;
1659 if (p->prev_same_hash)
1660 p->prev_same_hash->next_same_hash = p->next_same_hash;
1662 table[i] = p->next_same_hash;
1664 p->next_same_hash = table[hash];
1665 p->prev_same_hash = 0;
1667 table[hash]->prev_same_hash = p;
1673 /* Remove from the hash table all expressions that reference memory,
1674 or some of them as specified by *WRITES. */
1677 invalidate_memory (writes)
1678 struct write_data *writes;
1681 register struct table_elt *p, *next;
1682 int all = writes->all;
1683 int nonscalar = writes->nonscalar;
1685 for (i = 0; i < NBUCKETS; i++)
1686 for (p = table[i]; p; p = next)
1688 next = p->next_same_hash;
1691 || (nonscalar && p->in_struct)
1692 || cse_rtx_addr_varies_p (p->exp)))
1693 remove_from_table (p, i);
1697 /* Remove from the hash table any expression that is a call-clobbered
1698 register. Also update their TICK values. */
1701 invalidate_for_call ()
1703 int regno, endregno;
1706 struct table_elt *p, *next;
1709 /* Go through all the hard registers. For each that is clobbered in
1710 a CALL_INSN, remove the register from quantity chains and update
1711 reg_tick if defined. Also see if any of these registers is currently
1714 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
1715 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
1717 delete_reg_equiv (regno);
1718 if (reg_tick[regno] >= 0)
1721 in_table |= (TEST_HARD_REG_BIT (hard_regs_in_table, regno) != 0);
1724 /* In the case where we have no call-clobbered hard registers in the
1725 table, we are done. Otherwise, scan the table and remove any
1726 entry that overlaps a call-clobbered register. */
1729 for (hash = 0; hash < NBUCKETS; hash++)
1730 for (p = table[hash]; p; p = next)
1732 next = p->next_same_hash;
1734 if (GET_CODE (p->exp) != REG
1735 || REGNO (p->exp) >= FIRST_PSEUDO_REGISTER)
1738 regno = REGNO (p->exp);
1739 endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (p->exp));
1741 for (i = regno; i < endregno; i++)
1742 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1744 remove_from_table (p, hash);
1750 /* Given an expression X of type CONST,
1751 and ELT which is its table entry (or 0 if it
1752 is not in the hash table),
1753 return an alternate expression for X as a register plus integer.
1754 If none can be found, return 0. */
1757 use_related_value (x, elt)
1759 struct table_elt *elt;
1761 register struct table_elt *relt = 0;
1762 register struct table_elt *p, *q;
1763 HOST_WIDE_INT offset;
1765 /* First, is there anything related known?
1766 If we have a table element, we can tell from that.
1767 Otherwise, must look it up. */
1769 if (elt != 0 && elt->related_value != 0)
1771 else if (elt == 0 && GET_CODE (x) == CONST)
1773 rtx subexp = get_related_value (x);
1775 relt = lookup (subexp,
1776 safe_hash (subexp, GET_MODE (subexp)) % NBUCKETS,
1783 /* Search all related table entries for one that has an
1784 equivalent register. */
1789 /* This loop is strange in that it is executed in two different cases.
1790 The first is when X is already in the table. Then it is searching
1791 the RELATED_VALUE list of X's class (RELT). The second case is when
1792 X is not in the table. Then RELT points to a class for the related
1795 Ensure that, whatever case we are in, that we ignore classes that have
1796 the same value as X. */
1798 if (rtx_equal_p (x, p->exp))
1801 for (q = p->first_same_value; q; q = q->next_same_value)
1802 if (GET_CODE (q->exp) == REG)
1808 p = p->related_value;
1810 /* We went all the way around, so there is nothing to be found.
1811 Alternatively, perhaps RELT was in the table for some other reason
1812 and it has no related values recorded. */
1813 if (p == relt || p == 0)
1820 offset = (get_integer_term (x) - get_integer_term (p->exp));
1821 /* Note: OFFSET may be 0 if P->xexp and X are related by commutativity. */
1822 return plus_constant (q->exp, offset);
1825 /* Hash an rtx. We are careful to make sure the value is never negative.
1826 Equivalent registers hash identically.
1827 MODE is used in hashing for CONST_INTs only;
1828 otherwise the mode of X is used.
1830 Store 1 in do_not_record if any subexpression is volatile.
1832 Store 1 in hash_arg_in_memory if X contains a MEM rtx
1833 which does not have the RTX_UNCHANGING_P bit set.
1834 In this case, also store 1 in hash_arg_in_struct
1835 if there is a MEM rtx which has the MEM_IN_STRUCT_P bit set.
1837 Note that cse_insn knows that the hash code of a MEM expression
1838 is just (int) MEM plus the hash code of the address. */
1841 canon_hash (x, mode)
1843 enum machine_mode mode;
1846 register unsigned hash = 0;
1847 register enum rtx_code code;
1850 /* repeat is used to turn tail-recursion into iteration. */
1855 code = GET_CODE (x);
1860 register int regno = REGNO (x);
1862 /* On some machines, we can't record any non-fixed hard register,
1863 because extending its life will cause reload problems. We
1864 consider ap, fp, and sp to be fixed for this purpose.
1865 On all machines, we can't record any global registers. */
1867 if (regno < FIRST_PSEUDO_REGISTER
1868 && (global_regs[regno]
1869 #ifdef SMALL_REGISTER_CLASSES
1870 || (! fixed_regs[regno]
1871 && regno != FRAME_POINTER_REGNUM
1872 && regno != HARD_FRAME_POINTER_REGNUM
1873 && regno != ARG_POINTER_REGNUM
1874 && regno != STACK_POINTER_REGNUM)
1881 hash += ((unsigned) REG << 7) + (unsigned) reg_qty[regno];
1887 unsigned HOST_WIDE_INT tem = INTVAL (x);
1888 hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + tem;
1893 /* This is like the general case, except that it only counts
1894 the integers representing the constant. */
1895 hash += (unsigned) code + (unsigned) GET_MODE (x);
1896 for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
1898 unsigned tem = XINT (x, i);
1903 /* Assume there is only one rtx object for any given label. */
1906 += ((unsigned) LABEL_REF << 7) + (unsigned HOST_WIDE_INT) XEXP (x, 0);
1911 += ((unsigned) SYMBOL_REF << 7) + (unsigned HOST_WIDE_INT) XSTR (x, 0);
1915 if (MEM_VOLATILE_P (x))
1920 if (! RTX_UNCHANGING_P (x))
1922 hash_arg_in_memory = 1;
1923 if (MEM_IN_STRUCT_P (x)) hash_arg_in_struct = 1;
1925 /* Now that we have already found this special case,
1926 might as well speed it up as much as possible. */
1927 hash += (unsigned) MEM;
1938 case UNSPEC_VOLATILE:
1943 if (MEM_VOLATILE_P (x))
1950 i = GET_RTX_LENGTH (code) - 1;
1951 hash += (unsigned) code + (unsigned) GET_MODE (x);
1952 fmt = GET_RTX_FORMAT (code);
1957 rtx tem = XEXP (x, i);
1960 /* If the operand is a REG that is equivalent to a constant, hash
1961 as if we were hashing the constant, since we will be comparing
1963 if (tem != 0 && GET_CODE (tem) == REG
1964 && REGNO_QTY_VALID_P (REGNO (tem))
1965 && qty_mode[reg_qty[REGNO (tem)]] == GET_MODE (tem)
1966 && (tem1 = qty_const[reg_qty[REGNO (tem)]]) != 0
1967 && CONSTANT_P (tem1))
1970 /* If we are about to do the last recursive call
1971 needed at this level, change it into iteration.
1972 This function is called enough to be worth it. */
1978 hash += canon_hash (tem, 0);
1980 else if (fmt[i] == 'E')
1981 for (j = 0; j < XVECLEN (x, i); j++)
1982 hash += canon_hash (XVECEXP (x, i, j), 0);
1983 else if (fmt[i] == 's')
1985 register unsigned char *p = (unsigned char *) XSTR (x, i);
1990 else if (fmt[i] == 'i')
1992 register unsigned tem = XINT (x, i);
2001 /* Like canon_hash but with no side effects. */
2006 enum machine_mode mode;
2008 int save_do_not_record = do_not_record;
2009 int save_hash_arg_in_memory = hash_arg_in_memory;
2010 int save_hash_arg_in_struct = hash_arg_in_struct;
2011 unsigned hash = canon_hash (x, mode);
2012 hash_arg_in_memory = save_hash_arg_in_memory;
2013 hash_arg_in_struct = save_hash_arg_in_struct;
2014 do_not_record = save_do_not_record;
2018 /* Return 1 iff X and Y would canonicalize into the same thing,
2019 without actually constructing the canonicalization of either one.
2020 If VALIDATE is nonzero,
2021 we assume X is an expression being processed from the rtl
2022 and Y was found in the hash table. We check register refs
2023 in Y for being marked as valid.
2025 If EQUAL_VALUES is nonzero, we allow a register to match a constant value
2026 that is known to be in the register. Ordinarily, we don't allow them
2027 to match, because letting them match would cause unpredictable results
2028 in all the places that search a hash table chain for an equivalent
2029 for a given value. A possible equivalent that has different structure
2030 has its hash code computed from different data. Whether the hash code
2031 is the same as that of the the given value is pure luck. */
2034 exp_equiv_p (x, y, validate, equal_values)
2040 register enum rtx_code code;
2043 /* Note: it is incorrect to assume an expression is equivalent to itself
2044 if VALIDATE is nonzero. */
2045 if (x == y && !validate)
2047 if (x == 0 || y == 0)
2050 code = GET_CODE (x);
2051 if (code != GET_CODE (y))
2056 /* If X is a constant and Y is a register or vice versa, they may be
2057 equivalent. We only have to validate if Y is a register. */
2058 if (CONSTANT_P (x) && GET_CODE (y) == REG
2059 && REGNO_QTY_VALID_P (REGNO (y))
2060 && GET_MODE (y) == qty_mode[reg_qty[REGNO (y)]]
2061 && rtx_equal_p (x, qty_const[reg_qty[REGNO (y)]])
2062 && (! validate || reg_in_table[REGNO (y)] == reg_tick[REGNO (y)]))
2065 if (CONSTANT_P (y) && code == REG
2066 && REGNO_QTY_VALID_P (REGNO (x))
2067 && GET_MODE (x) == qty_mode[reg_qty[REGNO (x)]]
2068 && rtx_equal_p (y, qty_const[reg_qty[REGNO (x)]]))
2074 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
2075 if (GET_MODE (x) != GET_MODE (y))
2085 return INTVAL (x) == INTVAL (y);
2088 return XEXP (x, 0) == XEXP (y, 0);
2091 return XSTR (x, 0) == XSTR (y, 0);
2095 int regno = REGNO (y);
2097 = regno + (regno >= FIRST_PSEUDO_REGISTER ? 1
2098 : HARD_REGNO_NREGS (regno, GET_MODE (y)));
2101 /* If the quantities are not the same, the expressions are not
2102 equivalent. If there are and we are not to validate, they
2103 are equivalent. Otherwise, ensure all regs are up-to-date. */
2105 if (reg_qty[REGNO (x)] != reg_qty[regno])
2111 for (i = regno; i < endregno; i++)
2112 if (reg_in_table[i] != reg_tick[i])
2118 /* For commutative operations, check both orders. */
2126 return ((exp_equiv_p (XEXP (x, 0), XEXP (y, 0), validate, equal_values)
2127 && exp_equiv_p (XEXP (x, 1), XEXP (y, 1),
2128 validate, equal_values))
2129 || (exp_equiv_p (XEXP (x, 0), XEXP (y, 1),
2130 validate, equal_values)
2131 && exp_equiv_p (XEXP (x, 1), XEXP (y, 0),
2132 validate, equal_values)));
2135 /* Compare the elements. If any pair of corresponding elements
2136 fail to match, return 0 for the whole things. */
2138 fmt = GET_RTX_FORMAT (code);
2139 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2144 if (! exp_equiv_p (XEXP (x, i), XEXP (y, i), validate, equal_values))
2149 if (XVECLEN (x, i) != XVECLEN (y, i))
2151 for (j = 0; j < XVECLEN (x, i); j++)
2152 if (! exp_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j),
2153 validate, equal_values))
2158 if (strcmp (XSTR (x, i), XSTR (y, i)))
2163 if (XINT (x, i) != XINT (y, i))
2168 if (XWINT (x, i) != XWINT (y, i))
2183 /* Return 1 iff any subexpression of X matches Y.
2184 Here we do not require that X or Y be valid (for registers referred to)
2185 for being in the hash table. */
2192 register enum rtx_code code;
2198 if (x == 0 || y == 0)
2201 code = GET_CODE (x);
2202 /* If X as a whole has the same code as Y, they may match.
2204 if (code == GET_CODE (y))
2206 if (exp_equiv_p (x, y, 0, 1))
2210 /* X does not match, so try its subexpressions. */
2212 fmt = GET_RTX_FORMAT (code);
2213 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2222 if (refers_to_p (XEXP (x, i), y))
2225 else if (fmt[i] == 'E')
2228 for (j = 0; j < XVECLEN (x, i); j++)
2229 if (refers_to_p (XVECEXP (x, i, j), y))
2236 /* Given ADDR and SIZE (a memory address, and the size of the memory reference),
2237 set PBASE, PSTART, and PEND which correspond to the base of the address,
2238 the starting offset, and ending offset respectively.
2240 ADDR is known to be a nonvarying address. */
2242 /* ??? Despite what the comments say, this function is in fact frequently
2243 passed varying addresses. This does not appear to cause any problems. */
2246 set_nonvarying_address_components (addr, size, pbase, pstart, pend)
2250 HOST_WIDE_INT *pstart, *pend;
2253 HOST_WIDE_INT start, end;
2259 /* Registers with nonvarying addresses usually have constant equivalents;
2260 but the frame pointer register is also possible. */
2261 if (GET_CODE (base) == REG
2263 && REGNO_QTY_VALID_P (REGNO (base))
2264 && qty_mode[reg_qty[REGNO (base)]] == GET_MODE (base)
2265 && qty_const[reg_qty[REGNO (base)]] != 0)
2266 base = qty_const[reg_qty[REGNO (base)]];
2267 else if (GET_CODE (base) == PLUS
2268 && GET_CODE (XEXP (base, 1)) == CONST_INT
2269 && GET_CODE (XEXP (base, 0)) == REG
2271 && REGNO_QTY_VALID_P (REGNO (XEXP (base, 0)))
2272 && (qty_mode[reg_qty[REGNO (XEXP (base, 0))]]
2273 == GET_MODE (XEXP (base, 0)))
2274 && qty_const[reg_qty[REGNO (XEXP (base, 0))]])
2276 start = INTVAL (XEXP (base, 1));
2277 base = qty_const[reg_qty[REGNO (XEXP (base, 0))]];
2280 /* Handle everything that we can find inside an address that has been
2281 viewed as constant. */
2285 /* If no part of this switch does a "continue", the code outside
2286 will exit this loop. */
2288 switch (GET_CODE (base))
2291 /* By definition, operand1 of a LO_SUM is the associated constant
2292 address. Use the associated constant address as the base
2294 base = XEXP (base, 1);
2298 /* Strip off CONST. */
2299 base = XEXP (base, 0);
2303 if (GET_CODE (XEXP (base, 1)) == CONST_INT)
2305 start += INTVAL (XEXP (base, 1));
2306 base = XEXP (base, 0);
2312 /* Handle the case of an AND which is the negative of a power of
2313 two. This is used to represent unaligned memory operations. */
2314 if (GET_CODE (XEXP (base, 1)) == CONST_INT
2315 && exact_log2 (- INTVAL (XEXP (base, 1))) > 0)
2317 set_nonvarying_address_components (XEXP (base, 0), size,
2318 pbase, pstart, pend);
2320 /* Assume the worst misalignment. START is affected, but not
2321 END, so compensate but adjusting SIZE. Don't lose any
2322 constant we already had. */
2324 size = *pend - *pstart - INTVAL (XEXP (base, 1)) - 1;
2325 start += *pstart - INTVAL (XEXP (base, 1)) - 1;
2334 if (GET_CODE (base) == CONST_INT)
2336 start += INTVAL (base);
2342 /* Set the return values. */
2348 /* Return 1 iff any subexpression of X refers to memory
2349 at an address of BASE plus some offset
2350 such that any of the bytes' offsets fall between START (inclusive)
2351 and END (exclusive).
2353 The value is undefined if X is a varying address (as determined by
2354 cse_rtx_addr_varies_p). This function is not used in such cases.
2356 When used in the cse pass, `qty_const' is nonzero, and it is used
2357 to treat an address that is a register with a known constant value
2358 as if it were that constant value.
2359 In the loop pass, `qty_const' is zero, so this is not done. */
2362 refers_to_mem_p (x, base, start, end)
2364 HOST_WIDE_INT start, end;
2366 register HOST_WIDE_INT i;
2367 register enum rtx_code code;
2374 code = GET_CODE (x);
2377 register rtx addr = XEXP (x, 0); /* Get the address. */
2379 HOST_WIDE_INT mystart, myend;
2381 set_nonvarying_address_components (addr, GET_MODE_SIZE (GET_MODE (x)),
2382 &mybase, &mystart, &myend);
2385 /* refers_to_mem_p is never called with varying addresses.
2386 If the base addresses are not equal, there is no chance
2387 of the memory addresses conflicting. */
2388 if (! rtx_equal_p (mybase, base))
2391 return myend > start && mystart < end;
2394 /* X does not match, so try its subexpressions. */
2396 fmt = GET_RTX_FORMAT (code);
2397 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2406 if (refers_to_mem_p (XEXP (x, i), base, start, end))
2409 else if (fmt[i] == 'E')
2412 for (j = 0; j < XVECLEN (x, i); j++)
2413 if (refers_to_mem_p (XVECEXP (x, i, j), base, start, end))
2420 /* Nonzero if X refers to memory at a varying address;
2421 except that a register which has at the moment a known constant value
2422 isn't considered variable. */
2425 cse_rtx_addr_varies_p (x)
2428 /* We need not check for X and the equivalence class being of the same
2429 mode because if X is equivalent to a constant in some mode, it
2430 doesn't vary in any mode. */
2432 if (GET_CODE (x) == MEM
2433 && GET_CODE (XEXP (x, 0)) == REG
2434 && REGNO_QTY_VALID_P (REGNO (XEXP (x, 0)))
2435 && GET_MODE (XEXP (x, 0)) == qty_mode[reg_qty[REGNO (XEXP (x, 0))]]
2436 && qty_const[reg_qty[REGNO (XEXP (x, 0))]] != 0)
2439 if (GET_CODE (x) == MEM
2440 && GET_CODE (XEXP (x, 0)) == PLUS
2441 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2442 && GET_CODE (XEXP (XEXP (x, 0), 0)) == REG
2443 && REGNO_QTY_VALID_P (REGNO (XEXP (XEXP (x, 0), 0)))
2444 && (GET_MODE (XEXP (XEXP (x, 0), 0))
2445 == qty_mode[reg_qty[REGNO (XEXP (XEXP (x, 0), 0))]])
2446 && qty_const[reg_qty[REGNO (XEXP (XEXP (x, 0), 0))]])
2449 return rtx_addr_varies_p (x);
2452 /* Canonicalize an expression:
2453 replace each register reference inside it
2454 with the "oldest" equivalent register.
2456 If INSN is non-zero and we are replacing a pseudo with a hard register
2457 or vice versa, validate_change is used to ensure that INSN remains valid
2458 after we make our substitution. The calls are made with IN_GROUP non-zero
2459 so apply_change_group must be called upon the outermost return from this
2460 function (unless INSN is zero). The result of apply_change_group can
2461 generally be discarded since the changes we are making are optional. */
2469 register enum rtx_code code;
2475 code = GET_CODE (x);
2493 /* Never replace a hard reg, because hard regs can appear
2494 in more than one machine mode, and we must preserve the mode
2495 of each occurrence. Also, some hard regs appear in
2496 MEMs that are shared and mustn't be altered. Don't try to
2497 replace any reg that maps to a reg of class NO_REGS. */
2498 if (REGNO (x) < FIRST_PSEUDO_REGISTER
2499 || ! REGNO_QTY_VALID_P (REGNO (x)))
2502 first = qty_first_reg[reg_qty[REGNO (x)]];
2503 return (first >= FIRST_PSEUDO_REGISTER ? regno_reg_rtx[first]
2504 : REGNO_REG_CLASS (first) == NO_REGS ? x
2505 : gen_rtx (REG, qty_mode[reg_qty[REGNO (x)]], first));
2509 fmt = GET_RTX_FORMAT (code);
2510 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2516 rtx new = canon_reg (XEXP (x, i), insn);
2518 /* If replacing pseudo with hard reg or vice versa, ensure the
2519 insn remains valid. Likewise if the insn has MATCH_DUPs. */
2520 if (insn != 0 && new != 0
2521 && GET_CODE (new) == REG && GET_CODE (XEXP (x, i)) == REG
2522 && (((REGNO (new) < FIRST_PSEUDO_REGISTER)
2523 != (REGNO (XEXP (x, i)) < FIRST_PSEUDO_REGISTER))
2524 || insn_n_dups[recog_memoized (insn)] > 0))
2525 validate_change (insn, &XEXP (x, i), new, 1);
2529 else if (fmt[i] == 'E')
2530 for (j = 0; j < XVECLEN (x, i); j++)
2531 XVECEXP (x, i, j) = canon_reg (XVECEXP (x, i, j), insn);
2537 /* LOC is a location with INSN that is an operand address (the contents of
2538 a MEM). Find the best equivalent address to use that is valid for this
2541 On most CISC machines, complicated address modes are costly, and rtx_cost
2542 is a good approximation for that cost. However, most RISC machines have
2543 only a few (usually only one) memory reference formats. If an address is
2544 valid at all, it is often just as cheap as any other address. Hence, for
2545 RISC machines, we use the configuration macro `ADDRESS_COST' to compare the
2546 costs of various addresses. For two addresses of equal cost, choose the one
2547 with the highest `rtx_cost' value as that has the potential of eliminating
2548 the most insns. For equal costs, we choose the first in the equivalence
2549 class. Note that we ignore the fact that pseudo registers are cheaper
2550 than hard registers here because we would also prefer the pseudo registers.
2554 find_best_addr (insn, loc)
2558 struct table_elt *elt, *p;
2561 int found_better = 1;
2562 int save_do_not_record = do_not_record;
2563 int save_hash_arg_in_memory = hash_arg_in_memory;
2564 int save_hash_arg_in_struct = hash_arg_in_struct;
2569 /* Do not try to replace constant addresses or addresses of local and
2570 argument slots. These MEM expressions are made only once and inserted
2571 in many instructions, as well as being used to control symbol table
2572 output. It is not safe to clobber them.
2574 There are some uncommon cases where the address is already in a register
2575 for some reason, but we cannot take advantage of that because we have
2576 no easy way to unshare the MEM. In addition, looking up all stack
2577 addresses is costly. */
2578 if ((GET_CODE (addr) == PLUS
2579 && GET_CODE (XEXP (addr, 0)) == REG
2580 && GET_CODE (XEXP (addr, 1)) == CONST_INT
2581 && (regno = REGNO (XEXP (addr, 0)),
2582 regno == FRAME_POINTER_REGNUM || regno == HARD_FRAME_POINTER_REGNUM
2583 || regno == ARG_POINTER_REGNUM))
2584 || (GET_CODE (addr) == REG
2585 && (regno = REGNO (addr), regno == FRAME_POINTER_REGNUM
2586 || regno == HARD_FRAME_POINTER_REGNUM
2587 || regno == ARG_POINTER_REGNUM))
2588 || CONSTANT_ADDRESS_P (addr))
2591 /* If this address is not simply a register, try to fold it. This will
2592 sometimes simplify the expression. Many simplifications
2593 will not be valid, but some, usually applying the associative rule, will
2594 be valid and produce better code. */
2595 if (GET_CODE (addr) != REG
2596 && validate_change (insn, loc, fold_rtx (addr, insn), 0))
2599 /* If this address is not in the hash table, we can't look for equivalences
2600 of the whole address. Also, ignore if volatile. */
2603 hash = HASH (addr, Pmode);
2604 addr_volatile = do_not_record;
2605 do_not_record = save_do_not_record;
2606 hash_arg_in_memory = save_hash_arg_in_memory;
2607 hash_arg_in_struct = save_hash_arg_in_struct;
2612 elt = lookup (addr, hash, Pmode);
2614 #ifndef ADDRESS_COST
2617 our_cost = elt->cost;
2619 /* Find the lowest cost below ours that works. */
2620 for (elt = elt->first_same_value; elt; elt = elt->next_same_value)
2621 if (elt->cost < our_cost
2622 && (GET_CODE (elt->exp) == REG
2623 || exp_equiv_p (elt->exp, elt->exp, 1, 0))
2624 && validate_change (insn, loc,
2625 canon_reg (copy_rtx (elt->exp), NULL_RTX), 0))
2632 /* We need to find the best (under the criteria documented above) entry
2633 in the class that is valid. We use the `flag' field to indicate
2634 choices that were invalid and iterate until we can't find a better
2635 one that hasn't already been tried. */
2637 for (p = elt->first_same_value; p; p = p->next_same_value)
2640 while (found_better)
2642 int best_addr_cost = ADDRESS_COST (*loc);
2643 int best_rtx_cost = (elt->cost + 1) >> 1;
2644 struct table_elt *best_elt = elt;
2647 for (p = elt->first_same_value; p; p = p->next_same_value)
2649 && (GET_CODE (p->exp) == REG
2650 || exp_equiv_p (p->exp, p->exp, 1, 0))
2651 && (ADDRESS_COST (p->exp) < best_addr_cost
2652 || (ADDRESS_COST (p->exp) == best_addr_cost
2653 && (p->cost + 1) >> 1 > best_rtx_cost)))
2656 best_addr_cost = ADDRESS_COST (p->exp);
2657 best_rtx_cost = (p->cost + 1) >> 1;
2663 if (validate_change (insn, loc,
2664 canon_reg (copy_rtx (best_elt->exp),
2673 /* If the address is a binary operation with the first operand a register
2674 and the second a constant, do the same as above, but looking for
2675 equivalences of the register. Then try to simplify before checking for
2676 the best address to use. This catches a few cases: First is when we
2677 have REG+const and the register is another REG+const. We can often merge
2678 the constants and eliminate one insn and one register. It may also be
2679 that a machine has a cheap REG+REG+const. Finally, this improves the
2680 code on the Alpha for unaligned byte stores. */
2682 if (flag_expensive_optimizations
2683 && (GET_RTX_CLASS (GET_CODE (*loc)) == '2'
2684 || GET_RTX_CLASS (GET_CODE (*loc)) == 'c')
2685 && GET_CODE (XEXP (*loc, 0)) == REG
2686 && GET_CODE (XEXP (*loc, 1)) == CONST_INT)
2688 rtx c = XEXP (*loc, 1);
2691 hash = HASH (XEXP (*loc, 0), Pmode);
2692 do_not_record = save_do_not_record;
2693 hash_arg_in_memory = save_hash_arg_in_memory;
2694 hash_arg_in_struct = save_hash_arg_in_struct;
2696 elt = lookup (XEXP (*loc, 0), hash, Pmode);
2700 /* We need to find the best (under the criteria documented above) entry
2701 in the class that is valid. We use the `flag' field to indicate
2702 choices that were invalid and iterate until we can't find a better
2703 one that hasn't already been tried. */
2705 for (p = elt->first_same_value; p; p = p->next_same_value)
2708 while (found_better)
2710 int best_addr_cost = ADDRESS_COST (*loc);
2711 int best_rtx_cost = (COST (*loc) + 1) >> 1;
2712 struct table_elt *best_elt = elt;
2713 rtx best_rtx = *loc;
2716 /* This is at worst case an O(n^2) algorithm, so limit our search
2717 to the first 32 elements on the list. This avoids trouble
2718 compiling code with very long basic blocks that can easily
2719 call cse_gen_binary so many times that we run out of memory. */
2722 for (p = elt->first_same_value, count = 0;
2724 p = p->next_same_value, count++)
2726 && (GET_CODE (p->exp) == REG
2727 || exp_equiv_p (p->exp, p->exp, 1, 0)))
2729 rtx new = cse_gen_binary (GET_CODE (*loc), Pmode, p->exp, c);
2731 if ((ADDRESS_COST (new) < best_addr_cost
2732 || (ADDRESS_COST (new) == best_addr_cost
2733 && (COST (new) + 1) >> 1 > best_rtx_cost)))
2736 best_addr_cost = ADDRESS_COST (new);
2737 best_rtx_cost = (COST (new) + 1) >> 1;
2745 if (validate_change (insn, loc,
2746 canon_reg (copy_rtx (best_rtx),
2757 /* Given an operation (CODE, *PARG1, *PARG2), where code is a comparison
2758 operation (EQ, NE, GT, etc.), follow it back through the hash table and
2759 what values are being compared.
2761 *PARG1 and *PARG2 are updated to contain the rtx representing the values
2762 actually being compared. For example, if *PARG1 was (cc0) and *PARG2
2763 was (const_int 0), *PARG1 and *PARG2 will be set to the objects that were
2764 compared to produce cc0.
2766 The return value is the comparison operator and is either the code of
2767 A or the code corresponding to the inverse of the comparison. */
2769 static enum rtx_code
2770 find_comparison_args (code, parg1, parg2, pmode1, pmode2)
2773 enum machine_mode *pmode1, *pmode2;
2777 arg1 = *parg1, arg2 = *parg2;
2779 /* If ARG2 is const0_rtx, see what ARG1 is equivalent to. */
2781 while (arg2 == CONST0_RTX (GET_MODE (arg1)))
2783 /* Set non-zero when we find something of interest. */
2785 int reverse_code = 0;
2786 struct table_elt *p = 0;
2788 /* If arg1 is a COMPARE, extract the comparison arguments from it.
2789 On machines with CC0, this is the only case that can occur, since
2790 fold_rtx will return the COMPARE or item being compared with zero
2793 if (GET_CODE (arg1) == COMPARE && arg2 == const0_rtx)
2796 /* If ARG1 is a comparison operator and CODE is testing for
2797 STORE_FLAG_VALUE, get the inner arguments. */
2799 else if (GET_RTX_CLASS (GET_CODE (arg1)) == '<')
2802 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_INT
2803 && code == LT && STORE_FLAG_VALUE == -1)
2804 #ifdef FLOAT_STORE_FLAG_VALUE
2805 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_FLOAT
2806 && FLOAT_STORE_FLAG_VALUE < 0)
2811 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_INT
2812 && code == GE && STORE_FLAG_VALUE == -1)
2813 #ifdef FLOAT_STORE_FLAG_VALUE
2814 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_FLOAT
2815 && FLOAT_STORE_FLAG_VALUE < 0)
2818 x = arg1, reverse_code = 1;
2821 /* ??? We could also check for
2823 (ne (and (eq (...) (const_int 1))) (const_int 0))
2825 and related forms, but let's wait until we see them occurring. */
2828 /* Look up ARG1 in the hash table and see if it has an equivalence
2829 that lets us see what is being compared. */
2830 p = lookup (arg1, safe_hash (arg1, GET_MODE (arg1)) % NBUCKETS,
2832 if (p) p = p->first_same_value;
2834 for (; p; p = p->next_same_value)
2836 enum machine_mode inner_mode = GET_MODE (p->exp);
2838 /* If the entry isn't valid, skip it. */
2839 if (! exp_equiv_p (p->exp, p->exp, 1, 0))
2842 if (GET_CODE (p->exp) == COMPARE
2843 /* Another possibility is that this machine has a compare insn
2844 that includes the comparison code. In that case, ARG1 would
2845 be equivalent to a comparison operation that would set ARG1 to
2846 either STORE_FLAG_VALUE or zero. If this is an NE operation,
2847 ORIG_CODE is the actual comparison being done; if it is an EQ,
2848 we must reverse ORIG_CODE. On machine with a negative value
2849 for STORE_FLAG_VALUE, also look at LT and GE operations. */
2852 && GET_MODE_CLASS (inner_mode) == MODE_INT
2853 && (GET_MODE_BITSIZE (inner_mode)
2854 <= HOST_BITS_PER_WIDE_INT)
2855 && (STORE_FLAG_VALUE
2856 & ((HOST_WIDE_INT) 1
2857 << (GET_MODE_BITSIZE (inner_mode) - 1))))
2858 #ifdef FLOAT_STORE_FLAG_VALUE
2860 && GET_MODE_CLASS (inner_mode) == MODE_FLOAT
2861 && FLOAT_STORE_FLAG_VALUE < 0)
2864 && GET_RTX_CLASS (GET_CODE (p->exp)) == '<'))
2869 else if ((code == EQ
2871 && GET_MODE_CLASS (inner_mode) == MODE_INT
2872 && (GET_MODE_BITSIZE (inner_mode)
2873 <= HOST_BITS_PER_WIDE_INT)
2874 && (STORE_FLAG_VALUE
2875 & ((HOST_WIDE_INT) 1
2876 << (GET_MODE_BITSIZE (inner_mode) - 1))))
2877 #ifdef FLOAT_STORE_FLAG_VALUE
2879 && GET_MODE_CLASS (inner_mode) == MODE_FLOAT
2880 && FLOAT_STORE_FLAG_VALUE < 0)
2883 && GET_RTX_CLASS (GET_CODE (p->exp)) == '<')
2890 /* If this is fp + constant, the equivalent is a better operand since
2891 it may let us predict the value of the comparison. */
2892 else if (NONZERO_BASE_PLUS_P (p->exp))
2899 /* If we didn't find a useful equivalence for ARG1, we are done.
2900 Otherwise, set up for the next iteration. */
2904 arg1 = XEXP (x, 0), arg2 = XEXP (x, 1);
2905 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
2906 code = GET_CODE (x);
2909 code = reverse_condition (code);
2912 /* Return our results. Return the modes from before fold_rtx
2913 because fold_rtx might produce const_int, and then it's too late. */
2914 *pmode1 = GET_MODE (arg1), *pmode2 = GET_MODE (arg2);
2915 *parg1 = fold_rtx (arg1, 0), *parg2 = fold_rtx (arg2, 0);
2920 /* Try to simplify a unary operation CODE whose output mode is to be
2921 MODE with input operand OP whose mode was originally OP_MODE.
2922 Return zero if no simplification can be made. */
2925 simplify_unary_operation (code, mode, op, op_mode)
2927 enum machine_mode mode;
2929 enum machine_mode op_mode;
2931 register int width = GET_MODE_BITSIZE (mode);
2933 /* The order of these tests is critical so that, for example, we don't
2934 check the wrong mode (input vs. output) for a conversion operation,
2935 such as FIX. At some point, this should be simplified. */
2937 #if !defined(REAL_IS_NOT_DOUBLE) || defined(REAL_ARITHMETIC)
2939 if (code == FLOAT && GET_MODE (op) == VOIDmode
2940 && (GET_CODE (op) == CONST_DOUBLE || GET_CODE (op) == CONST_INT))
2942 HOST_WIDE_INT hv, lv;
2945 if (GET_CODE (op) == CONST_INT)
2946 lv = INTVAL (op), hv = INTVAL (op) < 0 ? -1 : 0;
2948 lv = CONST_DOUBLE_LOW (op), hv = CONST_DOUBLE_HIGH (op);
2950 #ifdef REAL_ARITHMETIC
2951 REAL_VALUE_FROM_INT (d, lv, hv);
2955 d = (double) (~ hv);
2956 d *= ((double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2))
2957 * (double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)));
2958 d += (double) (unsigned HOST_WIDE_INT) (~ lv);
2964 d *= ((double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2))
2965 * (double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)));
2966 d += (double) (unsigned HOST_WIDE_INT) lv;
2968 #endif /* REAL_ARITHMETIC */
2970 return CONST_DOUBLE_FROM_REAL_VALUE (d, mode);
2972 else if (code == UNSIGNED_FLOAT && GET_MODE (op) == VOIDmode
2973 && (GET_CODE (op) == CONST_DOUBLE || GET_CODE (op) == CONST_INT))
2975 HOST_WIDE_INT hv, lv;
2978 if (GET_CODE (op) == CONST_INT)
2979 lv = INTVAL (op), hv = INTVAL (op) < 0 ? -1 : 0;
2981 lv = CONST_DOUBLE_LOW (op), hv = CONST_DOUBLE_HIGH (op);
2983 if (GET_MODE_BITSIZE (op_mode) >= HOST_BITS_PER_WIDE_INT * 2)
2986 hv = 0, lv &= GET_MODE_MASK (op_mode);
2988 #ifdef REAL_ARITHMETIC
2989 REAL_VALUE_FROM_UNSIGNED_INT (d, lv, hv);
2992 d = (double) (unsigned HOST_WIDE_INT) hv;
2993 d *= ((double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2))
2994 * (double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)));
2995 d += (double) (unsigned HOST_WIDE_INT) lv;
2996 #endif /* REAL_ARITHMETIC */
2998 return CONST_DOUBLE_FROM_REAL_VALUE (d, mode);
3002 if (GET_CODE (op) == CONST_INT
3003 && width <= HOST_BITS_PER_WIDE_INT && width > 0)
3005 register HOST_WIDE_INT arg0 = INTVAL (op);
3006 register HOST_WIDE_INT val;
3019 val = (arg0 >= 0 ? arg0 : - arg0);
3023 /* Don't use ffs here. Instead, get low order bit and then its
3024 number. If arg0 is zero, this will return 0, as desired. */
3025 arg0 &= GET_MODE_MASK (mode);
3026 val = exact_log2 (arg0 & (- arg0)) + 1;
3034 if (op_mode == VOIDmode)
3036 if (GET_MODE_BITSIZE (op_mode) == HOST_BITS_PER_WIDE_INT)
3038 /* If we were really extending the mode,
3039 we would have to distinguish between zero-extension
3040 and sign-extension. */
3041 if (width != GET_MODE_BITSIZE (op_mode))
3045 else if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT)
3046 val = arg0 & ~((HOST_WIDE_INT) (-1) << GET_MODE_BITSIZE (op_mode));
3052 if (op_mode == VOIDmode)
3054 if (GET_MODE_BITSIZE (op_mode) == HOST_BITS_PER_WIDE_INT)
3056 /* If we were really extending the mode,
3057 we would have to distinguish between zero-extension
3058 and sign-extension. */
3059 if (width != GET_MODE_BITSIZE (op_mode))
3063 else if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT)
3066 = arg0 & ~((HOST_WIDE_INT) (-1) << GET_MODE_BITSIZE (op_mode));
3068 & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (op_mode) - 1)))
3069 val -= (HOST_WIDE_INT) 1 << GET_MODE_BITSIZE (op_mode);
3082 /* Clear the bits that don't belong in our mode,
3083 unless they and our sign bit are all one.
3084 So we get either a reasonable negative value or a reasonable
3085 unsigned value for this mode. */
3086 if (width < HOST_BITS_PER_WIDE_INT
3087 && ((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
3088 != ((HOST_WIDE_INT) (-1) << (width - 1))))
3089 val &= (1 << width) - 1;
3091 return GEN_INT (val);
3094 /* We can do some operations on integer CONST_DOUBLEs. Also allow
3095 for a DImode operation on a CONST_INT. */
3096 else if (GET_MODE (op) == VOIDmode && width <= HOST_BITS_PER_INT * 2
3097 && (GET_CODE (op) == CONST_DOUBLE || GET_CODE (op) == CONST_INT))
3099 HOST_WIDE_INT l1, h1, lv, hv;
3101 if (GET_CODE (op) == CONST_DOUBLE)
3102 l1 = CONST_DOUBLE_LOW (op), h1 = CONST_DOUBLE_HIGH (op);
3104 l1 = INTVAL (op), h1 = l1 < 0 ? -1 : 0;
3114 neg_double (l1, h1, &lv, &hv);
3119 neg_double (l1, h1, &lv, &hv);
3127 lv = HOST_BITS_PER_WIDE_INT + exact_log2 (h1 & (-h1)) + 1;
3129 lv = exact_log2 (l1 & (-l1)) + 1;
3133 /* This is just a change-of-mode, so do nothing. */
3137 if (op_mode == VOIDmode
3138 || GET_MODE_BITSIZE (op_mode) > HOST_BITS_PER_WIDE_INT)
3142 lv = l1 & GET_MODE_MASK (op_mode);
3146 if (op_mode == VOIDmode
3147 || GET_MODE_BITSIZE (op_mode) > HOST_BITS_PER_WIDE_INT)
3151 lv = l1 & GET_MODE_MASK (op_mode);
3152 if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT
3153 && (lv & ((HOST_WIDE_INT) 1
3154 << (GET_MODE_BITSIZE (op_mode) - 1))) != 0)
3155 lv -= (HOST_WIDE_INT) 1 << GET_MODE_BITSIZE (op_mode);
3157 hv = (lv < 0) ? ~ (HOST_WIDE_INT) 0 : 0;
3168 return immed_double_const (lv, hv, mode);
3171 #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
3172 else if (GET_CODE (op) == CONST_DOUBLE
3173 && GET_MODE_CLASS (mode) == MODE_FLOAT)
3179 if (setjmp (handler))
3180 /* There used to be a warning here, but that is inadvisable.
3181 People may want to cause traps, and the natural way
3182 to do it should not get a warning. */
3185 set_float_handler (handler);
3187 REAL_VALUE_FROM_CONST_DOUBLE (d, op);
3192 d = REAL_VALUE_NEGATE (d);
3196 if (REAL_VALUE_NEGATIVE (d))
3197 d = REAL_VALUE_NEGATE (d);
3200 case FLOAT_TRUNCATE:
3201 d = real_value_truncate (mode, d);
3205 /* All this does is change the mode. */
3209 d = REAL_VALUE_RNDZINT (d);
3213 d = REAL_VALUE_UNSIGNED_RNDZINT (d);
3223 x = CONST_DOUBLE_FROM_REAL_VALUE (d, mode);
3224 set_float_handler (NULL_PTR);
3228 else if (GET_CODE (op) == CONST_DOUBLE
3229 && GET_MODE_CLASS (GET_MODE (op)) == MODE_FLOAT
3230 && GET_MODE_CLASS (mode) == MODE_INT
3231 && width <= HOST_BITS_PER_WIDE_INT && width > 0)
3237 if (setjmp (handler))
3240 set_float_handler (handler);
3242 REAL_VALUE_FROM_CONST_DOUBLE (d, op);
3247 val = REAL_VALUE_FIX (d);
3251 val = REAL_VALUE_UNSIGNED_FIX (d);
3258 set_float_handler (NULL_PTR);
3260 /* Clear the bits that don't belong in our mode,
3261 unless they and our sign bit are all one.
3262 So we get either a reasonable negative value or a reasonable
3263 unsigned value for this mode. */
3264 if (width < HOST_BITS_PER_WIDE_INT
3265 && ((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
3266 != ((HOST_WIDE_INT) (-1) << (width - 1))))
3267 val &= ((HOST_WIDE_INT) 1 << width) - 1;
3269 return GEN_INT (val);
3272 /* This was formerly used only for non-IEEE float.
3273 eggert@twinsun.com says it is safe for IEEE also. */
3276 /* There are some simplifications we can do even if the operands
3282 /* (not (not X)) == X, similarly for NEG. */
3283 if (GET_CODE (op) == code)
3284 return XEXP (op, 0);
3288 /* (sign_extend (truncate (minus (label_ref L1) (label_ref L2))))
3289 becomes just the MINUS if its mode is MODE. This allows
3290 folding switch statements on machines using casesi (such as
3292 if (GET_CODE (op) == TRUNCATE
3293 && GET_MODE (XEXP (op, 0)) == mode
3294 && GET_CODE (XEXP (op, 0)) == MINUS
3295 && GET_CODE (XEXP (XEXP (op, 0), 0)) == LABEL_REF
3296 && GET_CODE (XEXP (XEXP (op, 0), 1)) == LABEL_REF)
3297 return XEXP (op, 0);
3305 /* Simplify a binary operation CODE with result mode MODE, operating on OP0
3306 and OP1. Return 0 if no simplification is possible.
3308 Don't use this for relational operations such as EQ or LT.
3309 Use simplify_relational_operation instead. */
3312 simplify_binary_operation (code, mode, op0, op1)
3314 enum machine_mode mode;
3317 register HOST_WIDE_INT arg0, arg1, arg0s, arg1s;
3319 int width = GET_MODE_BITSIZE (mode);
3322 /* Relational operations don't work here. We must know the mode
3323 of the operands in order to do the comparison correctly.
3324 Assuming a full word can give incorrect results.
3325 Consider comparing 128 with -128 in QImode. */
3327 if (GET_RTX_CLASS (code) == '<')
3330 #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
3331 if (GET_MODE_CLASS (mode) == MODE_FLOAT
3332 && GET_CODE (op0) == CONST_DOUBLE && GET_CODE (op1) == CONST_DOUBLE
3333 && mode == GET_MODE (op0) && mode == GET_MODE (op1))
3335 REAL_VALUE_TYPE f0, f1, value;
3338 if (setjmp (handler))
3341 set_float_handler (handler);
3343 REAL_VALUE_FROM_CONST_DOUBLE (f0, op0);
3344 REAL_VALUE_FROM_CONST_DOUBLE (f1, op1);
3345 f0 = real_value_truncate (mode, f0);
3346 f1 = real_value_truncate (mode, f1);
3348 #ifdef REAL_ARITHMETIC
3349 REAL_ARITHMETIC (value, rtx_to_tree_code (code), f0, f1);
3363 #ifndef REAL_INFINITY
3370 value = MIN (f0, f1);
3373 value = MAX (f0, f1);
3380 value = real_value_truncate (mode, value);
3381 set_float_handler (NULL_PTR);
3382 return CONST_DOUBLE_FROM_REAL_VALUE (value, mode);
3384 #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
3386 /* We can fold some multi-word operations. */
3387 if (GET_MODE_CLASS (mode) == MODE_INT
3388 && width == HOST_BITS_PER_WIDE_INT * 2
3389 && (GET_CODE (op0) == CONST_DOUBLE || GET_CODE (op0) == CONST_INT)
3390 && (GET_CODE (op1) == CONST_DOUBLE || GET_CODE (op1) == CONST_INT))
3392 HOST_WIDE_INT l1, l2, h1, h2, lv, hv;
3394 if (GET_CODE (op0) == CONST_DOUBLE)
3395 l1 = CONST_DOUBLE_LOW (op0), h1 = CONST_DOUBLE_HIGH (op0);
3397 l1 = INTVAL (op0), h1 = l1 < 0 ? -1 : 0;
3399 if (GET_CODE (op1) == CONST_DOUBLE)
3400 l2 = CONST_DOUBLE_LOW (op1), h2 = CONST_DOUBLE_HIGH (op1);
3402 l2 = INTVAL (op1), h2 = l2 < 0 ? -1 : 0;
3407 /* A - B == A + (-B). */
3408 neg_double (l2, h2, &lv, &hv);
3411 /* .. fall through ... */
3414 add_double (l1, h1, l2, h2, &lv, &hv);
3418 mul_double (l1, h1, l2, h2, &lv, &hv);
3421 case DIV: case MOD: case UDIV: case UMOD:
3422 /* We'd need to include tree.h to do this and it doesn't seem worth
3427 lv = l1 & l2, hv = h1 & h2;
3431 lv = l1 | l2, hv = h1 | h2;
3435 lv = l1 ^ l2, hv = h1 ^ h2;
3441 && ((unsigned HOST_WIDE_INT) l1
3442 < (unsigned HOST_WIDE_INT) l2)))
3451 && ((unsigned HOST_WIDE_INT) l1
3452 > (unsigned HOST_WIDE_INT) l2)))
3459 if ((unsigned HOST_WIDE_INT) h1 < (unsigned HOST_WIDE_INT) h2
3461 && ((unsigned HOST_WIDE_INT) l1
3462 < (unsigned HOST_WIDE_INT) l2)))
3469 if ((unsigned HOST_WIDE_INT) h1 > (unsigned HOST_WIDE_INT) h2
3471 && ((unsigned HOST_WIDE_INT) l1
3472 > (unsigned HOST_WIDE_INT) l2)))
3478 case LSHIFTRT: case ASHIFTRT:
3480 case ROTATE: case ROTATERT:
3481 #ifdef SHIFT_COUNT_TRUNCATED
3482 if (SHIFT_COUNT_TRUNCATED)
3483 l2 &= (GET_MODE_BITSIZE (mode) - 1), h2 = 0;
3486 if (h2 != 0 || l2 < 0 || l2 >= GET_MODE_BITSIZE (mode))
3489 if (code == LSHIFTRT || code == ASHIFTRT)
3490 rshift_double (l1, h1, l2, GET_MODE_BITSIZE (mode), &lv, &hv,
3492 else if (code == ASHIFT)
3493 lshift_double (l1, h1, l2, GET_MODE_BITSIZE (mode), &lv, &hv, 1);
3494 else if (code == ROTATE)
3495 lrotate_double (l1, h1, l2, GET_MODE_BITSIZE (mode), &lv, &hv);
3496 else /* code == ROTATERT */
3497 rrotate_double (l1, h1, l2, GET_MODE_BITSIZE (mode), &lv, &hv);
3504 return immed_double_const (lv, hv, mode);
3507 if (GET_CODE (op0) != CONST_INT || GET_CODE (op1) != CONST_INT
3508 || width > HOST_BITS_PER_WIDE_INT || width == 0)
3510 /* Even if we can't compute a constant result,
3511 there are some cases worth simplifying. */
3516 /* In IEEE floating point, x+0 is not the same as x. Similarly
3517 for the other optimizations below. */
3518 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
3519 && FLOAT_MODE_P (mode) && ! flag_fast_math)
3522 if (op1 == CONST0_RTX (mode))
3525 /* ((-a) + b) -> (b - a) and similarly for (a + (-b)) */
3526 if (GET_CODE (op0) == NEG)
3527 return cse_gen_binary (MINUS, mode, op1, XEXP (op0, 0));
3528 else if (GET_CODE (op1) == NEG)
3529 return cse_gen_binary (MINUS, mode, op0, XEXP (op1, 0));
3531 /* Handle both-operands-constant cases. We can only add
3532 CONST_INTs to constants since the sum of relocatable symbols
3533 can't be handled by most assemblers. Don't add CONST_INT
3534 to CONST_INT since overflow won't be computed properly if wider
3535 than HOST_BITS_PER_WIDE_INT. */
3537 if (CONSTANT_P (op0) && GET_MODE (op0) != VOIDmode
3538 && GET_CODE (op1) == CONST_INT)
3539 return plus_constant (op0, INTVAL (op1));
3540 else if (CONSTANT_P (op1) && GET_MODE (op1) != VOIDmode
3541 && GET_CODE (op0) == CONST_INT)
3542 return plus_constant (op1, INTVAL (op0));
3544 /* See if this is something like X * C - X or vice versa or
3545 if the multiplication is written as a shift. If so, we can
3546 distribute and make a new multiply, shift, or maybe just
3547 have X (if C is 2 in the example above). But don't make
3548 real multiply if we didn't have one before. */
3550 if (! FLOAT_MODE_P (mode))
3552 HOST_WIDE_INT coeff0 = 1, coeff1 = 1;
3553 rtx lhs = op0, rhs = op1;
3556 if (GET_CODE (lhs) == NEG)
3557 coeff0 = -1, lhs = XEXP (lhs, 0);
3558 else if (GET_CODE (lhs) == MULT
3559 && GET_CODE (XEXP (lhs, 1)) == CONST_INT)
3561 coeff0 = INTVAL (XEXP (lhs, 1)), lhs = XEXP (lhs, 0);
3564 else if (GET_CODE (lhs) == ASHIFT
3565 && GET_CODE (XEXP (lhs, 1)) == CONST_INT
3566 && INTVAL (XEXP (lhs, 1)) >= 0
3567 && INTVAL (XEXP (lhs, 1)) < HOST_BITS_PER_WIDE_INT)
3569 coeff0 = ((HOST_WIDE_INT) 1) << INTVAL (XEXP (lhs, 1));
3570 lhs = XEXP (lhs, 0);
3573 if (GET_CODE (rhs) == NEG)
3574 coeff1 = -1, rhs = XEXP (rhs, 0);
3575 else if (GET_CODE (rhs) == MULT
3576 && GET_CODE (XEXP (rhs, 1)) == CONST_INT)
3578 coeff1 = INTVAL (XEXP (rhs, 1)), rhs = XEXP (rhs, 0);
3581 else if (GET_CODE (rhs) == ASHIFT
3582 && GET_CODE (XEXP (rhs, 1)) == CONST_INT
3583 && INTVAL (XEXP (rhs, 1)) >= 0
3584 && INTVAL (XEXP (rhs, 1)) < HOST_BITS_PER_WIDE_INT)
3586 coeff1 = ((HOST_WIDE_INT) 1) << INTVAL (XEXP (rhs, 1));
3587 rhs = XEXP (rhs, 0);
3590 if (rtx_equal_p (lhs, rhs))
3592 tem = cse_gen_binary (MULT, mode, lhs,
3593 GEN_INT (coeff0 + coeff1));
3594 return (GET_CODE (tem) == MULT && ! had_mult) ? 0 : tem;
3598 /* If one of the operands is a PLUS or a MINUS, see if we can
3599 simplify this by the associative law.
3600 Don't use the associative law for floating point.
3601 The inaccuracy makes it nonassociative,
3602 and subtle programs can break if operations are associated. */
3604 if (INTEGRAL_MODE_P (mode)
3605 && (GET_CODE (op0) == PLUS || GET_CODE (op0) == MINUS
3606 || GET_CODE (op1) == PLUS || GET_CODE (op1) == MINUS)
3607 && (tem = simplify_plus_minus (code, mode, op0, op1)) != 0)
3613 /* Convert (compare FOO (const_int 0)) to FOO unless we aren't
3614 using cc0, in which case we want to leave it as a COMPARE
3615 so we can distinguish it from a register-register-copy.
3617 In IEEE floating point, x-0 is not the same as x. */
3619 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3620 || ! FLOAT_MODE_P (mode) || flag_fast_math)
3621 && op1 == CONST0_RTX (mode))
3624 /* Do nothing here. */
3629 /* None of these optimizations can be done for IEEE
3631 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
3632 && FLOAT_MODE_P (mode) && ! flag_fast_math)
3635 /* We can't assume x-x is 0 even with non-IEEE floating point,
3636 but since it is zero except in very strange circumstances, we
3637 will treat it as zero with -ffast-math. */
3638 if (rtx_equal_p (op0, op1)
3639 && ! side_effects_p (op0)
3640 && (! FLOAT_MODE_P (mode) || flag_fast_math))
3641 return CONST0_RTX (mode);
3643 /* Change subtraction from zero into negation. */
3644 if (op0 == CONST0_RTX (mode))
3645 return gen_rtx (NEG, mode, op1);
3647 /* (-1 - a) is ~a. */
3648 if (op0 == constm1_rtx)
3649 return gen_rtx (NOT, mode, op1);
3651 /* Subtracting 0 has no effect. */
3652 if (op1 == CONST0_RTX (mode))
3655 /* See if this is something like X * C - X or vice versa or
3656 if the multiplication is written as a shift. If so, we can
3657 distribute and make a new multiply, shift, or maybe just
3658 have X (if C is 2 in the example above). But don't make
3659 real multiply if we didn't have one before. */
3661 if (! FLOAT_MODE_P (mode))
3663 HOST_WIDE_INT coeff0 = 1, coeff1 = 1;
3664 rtx lhs = op0, rhs = op1;
3667 if (GET_CODE (lhs) == NEG)
3668 coeff0 = -1, lhs = XEXP (lhs, 0);
3669 else if (GET_CODE (lhs) == MULT
3670 && GET_CODE (XEXP (lhs, 1)) == CONST_INT)
3672 coeff0 = INTVAL (XEXP (lhs, 1)), lhs = XEXP (lhs, 0);
3675 else if (GET_CODE (lhs) == ASHIFT
3676 && GET_CODE (XEXP (lhs, 1)) == CONST_INT
3677 && INTVAL (XEXP (lhs, 1)) >= 0
3678 && INTVAL (XEXP (lhs, 1)) < HOST_BITS_PER_WIDE_INT)
3680 coeff0 = ((HOST_WIDE_INT) 1) << INTVAL (XEXP (lhs, 1));
3681 lhs = XEXP (lhs, 0);
3684 if (GET_CODE (rhs) == NEG)
3685 coeff1 = - 1, rhs = XEXP (rhs, 0);
3686 else if (GET_CODE (rhs) == MULT
3687 && GET_CODE (XEXP (rhs, 1)) == CONST_INT)
3689 coeff1 = INTVAL (XEXP (rhs, 1)), rhs = XEXP (rhs, 0);
3692 else if (GET_CODE (rhs) == ASHIFT
3693 && GET_CODE (XEXP (rhs, 1)) == CONST_INT
3694 && INTVAL (XEXP (rhs, 1)) >= 0
3695 && INTVAL (XEXP (rhs, 1)) < HOST_BITS_PER_WIDE_INT)
3697 coeff1 = ((HOST_WIDE_INT) 1) << INTVAL (XEXP (rhs, 1));
3698 rhs = XEXP (rhs, 0);
3701 if (rtx_equal_p (lhs, rhs))
3703 tem = cse_gen_binary (MULT, mode, lhs,
3704 GEN_INT (coeff0 - coeff1));
3705 return (GET_CODE (tem) == MULT && ! had_mult) ? 0 : tem;
3709 /* (a - (-b)) -> (a + b). */
3710 if (GET_CODE (op1) == NEG)
3711 return cse_gen_binary (PLUS, mode, op0, XEXP (op1, 0));
3713 /* If one of the operands is a PLUS or a MINUS, see if we can
3714 simplify this by the associative law.
3715 Don't use the associative law for floating point.
3716 The inaccuracy makes it nonassociative,
3717 and subtle programs can break if operations are associated. */
3719 if (INTEGRAL_MODE_P (mode)
3720 && (GET_CODE (op0) == PLUS || GET_CODE (op0) == MINUS
3721 || GET_CODE (op1) == PLUS || GET_CODE (op1) == MINUS)
3722 && (tem = simplify_plus_minus (code, mode, op0, op1)) != 0)
3725 /* Don't let a relocatable value get a negative coeff. */
3726 if (GET_CODE (op1) == CONST_INT && GET_MODE (op0) != VOIDmode)
3727 return plus_constant (op0, - INTVAL (op1));
3731 if (op1 == constm1_rtx)
3733 tem = simplify_unary_operation (NEG, mode, op0, mode);
3735 return tem ? tem : gen_rtx (NEG, mode, op0);
3738 /* In IEEE floating point, x*0 is not always 0. */
3739 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3740 || ! FLOAT_MODE_P (mode) || flag_fast_math)
3741 && op1 == CONST0_RTX (mode)
3742 && ! side_effects_p (op0))
3745 /* In IEEE floating point, x*1 is not equivalent to x for nans.
3746 However, ANSI says we can drop signals,
3747 so we can do this anyway. */
3748 if (op1 == CONST1_RTX (mode))
3751 /* Convert multiply by constant power of two into shift unless
3752 we are still generating RTL. This test is a kludge. */
3753 if (GET_CODE (op1) == CONST_INT
3754 && (val = exact_log2 (INTVAL (op1))) >= 0
3755 && ! rtx_equal_function_value_matters)
3756 return gen_rtx (ASHIFT, mode, op0, GEN_INT (val));
3758 if (GET_CODE (op1) == CONST_DOUBLE
3759 && GET_MODE_CLASS (GET_MODE (op1)) == MODE_FLOAT)
3763 int op1is2, op1ism1;
3765 if (setjmp (handler))
3768 set_float_handler (handler);
3769 REAL_VALUE_FROM_CONST_DOUBLE (d, op1);
3770 op1is2 = REAL_VALUES_EQUAL (d, dconst2);
3771 op1ism1 = REAL_VALUES_EQUAL (d, dconstm1);
3772 set_float_handler (NULL_PTR);
3774 /* x*2 is x+x and x*(-1) is -x */
3775 if (op1is2 && GET_MODE (op0) == mode)
3776 return gen_rtx (PLUS, mode, op0, copy_rtx (op0));
3778 else if (op1ism1 && GET_MODE (op0) == mode)
3779 return gen_rtx (NEG, mode, op0);
3784 if (op1 == const0_rtx)
3786 if (GET_CODE (op1) == CONST_INT
3787 && (INTVAL (op1) & GET_MODE_MASK (mode)) == GET_MODE_MASK (mode))
3789 if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3791 /* A | (~A) -> -1 */
3792 if (((GET_CODE (op0) == NOT && rtx_equal_p (XEXP (op0, 0), op1))
3793 || (GET_CODE (op1) == NOT && rtx_equal_p (XEXP (op1, 0), op0)))
3794 && ! side_effects_p (op0)
3795 && GET_MODE_CLASS (mode) != MODE_CC)
3800 if (op1 == const0_rtx)
3802 if (GET_CODE (op1) == CONST_INT
3803 && (INTVAL (op1) & GET_MODE_MASK (mode)) == GET_MODE_MASK (mode))
3804 return gen_rtx (NOT, mode, op0);
3805 if (op0 == op1 && ! side_effects_p (op0)
3806 && GET_MODE_CLASS (mode) != MODE_CC)
3811 if (op1 == const0_rtx && ! side_effects_p (op0))
3813 if (GET_CODE (op1) == CONST_INT
3814 && (INTVAL (op1) & GET_MODE_MASK (mode)) == GET_MODE_MASK (mode))
3816 if (op0 == op1 && ! side_effects_p (op0)
3817 && GET_MODE_CLASS (mode) != MODE_CC)
3820 if (((GET_CODE (op0) == NOT && rtx_equal_p (XEXP (op0, 0), op1))
3821 || (GET_CODE (op1) == NOT && rtx_equal_p (XEXP (op1, 0), op0)))
3822 && ! side_effects_p (op0)
3823 && GET_MODE_CLASS (mode) != MODE_CC)
3828 /* Convert divide by power of two into shift (divide by 1 handled
3830 if (GET_CODE (op1) == CONST_INT
3831 && (arg1 = exact_log2 (INTVAL (op1))) > 0)
3832 return gen_rtx (LSHIFTRT, mode, op0, GEN_INT (arg1));
3834 /* ... fall through ... */
3837 if (op1 == CONST1_RTX (mode))
3840 /* In IEEE floating point, 0/x is not always 0. */
3841 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3842 || ! FLOAT_MODE_P (mode) || flag_fast_math)
3843 && op0 == CONST0_RTX (mode)
3844 && ! side_effects_p (op1))
3847 #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
3848 /* Change division by a constant into multiplication. Only do
3849 this with -ffast-math until an expert says it is safe in
3851 else if (GET_CODE (op1) == CONST_DOUBLE
3852 && GET_MODE_CLASS (GET_MODE (op1)) == MODE_FLOAT
3853 && op1 != CONST0_RTX (mode)
3857 REAL_VALUE_FROM_CONST_DOUBLE (d, op1);
3859 if (! REAL_VALUES_EQUAL (d, dconst0))
3861 #if defined (REAL_ARITHMETIC)
3862 REAL_ARITHMETIC (d, rtx_to_tree_code (DIV), dconst1, d);
3863 return gen_rtx (MULT, mode, op0,
3864 CONST_DOUBLE_FROM_REAL_VALUE (d, mode));
3866 return gen_rtx (MULT, mode, op0,
3867 CONST_DOUBLE_FROM_REAL_VALUE (1./d, mode));
3875 /* Handle modulus by power of two (mod with 1 handled below). */
3876 if (GET_CODE (op1) == CONST_INT
3877 && exact_log2 (INTVAL (op1)) > 0)
3878 return gen_rtx (AND, mode, op0, GEN_INT (INTVAL (op1) - 1));
3880 /* ... fall through ... */
3883 if ((op0 == const0_rtx || op1 == const1_rtx)
3884 && ! side_effects_p (op0) && ! side_effects_p (op1))
3890 /* Rotating ~0 always results in ~0. */
3891 if (GET_CODE (op0) == CONST_INT && width <= HOST_BITS_PER_WIDE_INT
3892 && INTVAL (op0) == GET_MODE_MASK (mode)
3893 && ! side_effects_p (op1))
3896 /* ... fall through ... */
3901 if (op1 == const0_rtx)
3903 if (op0 == const0_rtx && ! side_effects_p (op1))
3908 if (width <= HOST_BITS_PER_WIDE_INT && GET_CODE (op1) == CONST_INT
3909 && INTVAL (op1) == (HOST_WIDE_INT) 1 << (width -1)
3910 && ! side_effects_p (op0))
3912 else if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3917 if (width <= HOST_BITS_PER_WIDE_INT && GET_CODE (op1) == CONST_INT
3919 == (unsigned HOST_WIDE_INT) GET_MODE_MASK (mode) >> 1)
3920 && ! side_effects_p (op0))
3922 else if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3927 if (op1 == const0_rtx && ! side_effects_p (op0))
3929 else if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3934 if (op1 == constm1_rtx && ! side_effects_p (op0))
3936 else if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3947 /* Get the integer argument values in two forms:
3948 zero-extended in ARG0, ARG1 and sign-extended in ARG0S, ARG1S. */
3950 arg0 = INTVAL (op0);
3951 arg1 = INTVAL (op1);
3953 if (width < HOST_BITS_PER_WIDE_INT)
3955 arg0 &= ((HOST_WIDE_INT) 1 << width) - 1;
3956 arg1 &= ((HOST_WIDE_INT) 1 << width) - 1;
3959 if (arg0s & ((HOST_WIDE_INT) 1 << (width - 1)))
3960 arg0s |= ((HOST_WIDE_INT) (-1) << width);
3963 if (arg1s & ((HOST_WIDE_INT) 1 << (width - 1)))
3964 arg1s |= ((HOST_WIDE_INT) (-1) << width);
3972 /* Compute the value of the arithmetic. */
3977 val = arg0s + arg1s;
3981 val = arg0s - arg1s;
3985 val = arg0s * arg1s;
3991 val = arg0s / arg1s;
3997 val = arg0s % arg1s;
4003 val = (unsigned HOST_WIDE_INT) arg0 / arg1;
4009 val = (unsigned HOST_WIDE_INT) arg0 % arg1;
4025 /* If shift count is undefined, don't fold it; let the machine do
4026 what it wants. But truncate it if the machine will do that. */
4030 #ifdef SHIFT_COUNT_TRUNCATED
4031 if (SHIFT_COUNT_TRUNCATED)
4035 val = ((unsigned HOST_WIDE_INT) arg0) >> arg1;
4042 #ifdef SHIFT_COUNT_TRUNCATED
4043 if (SHIFT_COUNT_TRUNCATED)
4047 val = ((unsigned HOST_WIDE_INT) arg0) << arg1;
4054 #ifdef SHIFT_COUNT_TRUNCATED
4055 if (SHIFT_COUNT_TRUNCATED)
4059 val = arg0s >> arg1;
4061 /* Bootstrap compiler may not have sign extended the right shift.
4062 Manually extend the sign to insure bootstrap cc matches gcc. */
4063 if (arg0s < 0 && arg1 > 0)
4064 val |= ((HOST_WIDE_INT) -1) << (HOST_BITS_PER_WIDE_INT - arg1);
4073 val = ((((unsigned HOST_WIDE_INT) arg0) << (width - arg1))
4074 | (((unsigned HOST_WIDE_INT) arg0) >> arg1));
4082 val = ((((unsigned HOST_WIDE_INT) arg0) << arg1)
4083 | (((unsigned HOST_WIDE_INT) arg0) >> (width - arg1)));
4087 /* Do nothing here. */
4091 val = arg0s <= arg1s ? arg0s : arg1s;
4095 val = ((unsigned HOST_WIDE_INT) arg0
4096 <= (unsigned HOST_WIDE_INT) arg1 ? arg0 : arg1);
4100 val = arg0s > arg1s ? arg0s : arg1s;
4104 val = ((unsigned HOST_WIDE_INT) arg0
4105 > (unsigned HOST_WIDE_INT) arg1 ? arg0 : arg1);
4112 /* Clear the bits that don't belong in our mode, unless they and our sign
4113 bit are all one. So we get either a reasonable negative value or a
4114 reasonable unsigned value for this mode. */
4115 if (width < HOST_BITS_PER_WIDE_INT
4116 && ((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
4117 != ((HOST_WIDE_INT) (-1) << (width - 1))))
4118 val &= ((HOST_WIDE_INT) 1 << width) - 1;
4120 return GEN_INT (val);
4123 /* Simplify a PLUS or MINUS, at least one of whose operands may be another
4126 Rather than test for specific case, we do this by a brute-force method
4127 and do all possible simplifications until no more changes occur. Then
4128 we rebuild the operation. */
4131 simplify_plus_minus (code, mode, op0, op1)
4133 enum machine_mode mode;
4139 int n_ops = 2, input_ops = 2, input_consts = 0, n_consts = 0;
4140 int first = 1, negate = 0, changed;
4143 bzero ((char *) ops, sizeof ops);
4145 /* Set up the two operands and then expand them until nothing has been
4146 changed. If we run out of room in our array, give up; this should
4147 almost never happen. */
4149 ops[0] = op0, ops[1] = op1, negs[0] = 0, negs[1] = (code == MINUS);
4156 for (i = 0; i < n_ops; i++)
4157 switch (GET_CODE (ops[i]))
4164 ops[n_ops] = XEXP (ops[i], 1);
4165 negs[n_ops++] = GET_CODE (ops[i]) == MINUS ? !negs[i] : negs[i];
4166 ops[i] = XEXP (ops[i], 0);
4172 ops[i] = XEXP (ops[i], 0);
4173 negs[i] = ! negs[i];
4178 ops[i] = XEXP (ops[i], 0);
4184 /* ~a -> (-a - 1) */
4187 ops[n_ops] = constm1_rtx;
4188 negs[n_ops++] = negs[i];
4189 ops[i] = XEXP (ops[i], 0);
4190 negs[i] = ! negs[i];
4197 ops[i] = GEN_INT (- INTVAL (ops[i])), negs[i] = 0, changed = 1;
4202 /* If we only have two operands, we can't do anything. */
4206 /* Now simplify each pair of operands until nothing changes. The first
4207 time through just simplify constants against each other. */
4214 for (i = 0; i < n_ops - 1; i++)
4215 for (j = i + 1; j < n_ops; j++)
4216 if (ops[i] != 0 && ops[j] != 0
4217 && (! first || (CONSTANT_P (ops[i]) && CONSTANT_P (ops[j]))))
4219 rtx lhs = ops[i], rhs = ops[j];
4220 enum rtx_code ncode = PLUS;
4222 if (negs[i] && ! negs[j])
4223 lhs = ops[j], rhs = ops[i], ncode = MINUS;
4224 else if (! negs[i] && negs[j])
4227 tem = simplify_binary_operation (ncode, mode, lhs, rhs);
4230 ops[i] = tem, ops[j] = 0;
4231 negs[i] = negs[i] && negs[j];
4232 if (GET_CODE (tem) == NEG)
4233 ops[i] = XEXP (tem, 0), negs[i] = ! negs[i];
4235 if (GET_CODE (ops[i]) == CONST_INT && negs[i])
4236 ops[i] = GEN_INT (- INTVAL (ops[i])), negs[i] = 0;
4244 /* Pack all the operands to the lower-numbered entries and give up if
4245 we didn't reduce the number of operands we had. Make sure we
4246 count a CONST as two operands. If we have the same number of
4247 operands, but have made more CONSTs than we had, this is also
4248 an improvement, so accept it. */
4250 for (i = 0, j = 0; j < n_ops; j++)
4253 ops[i] = ops[j], negs[i++] = negs[j];
4254 if (GET_CODE (ops[j]) == CONST)
4258 if (i + n_consts > input_ops
4259 || (i + n_consts == input_ops && n_consts <= input_consts))
4264 /* If we have a CONST_INT, put it last. */
4265 for (i = 0; i < n_ops - 1; i++)
4266 if (GET_CODE (ops[i]) == CONST_INT)
4268 tem = ops[n_ops - 1], ops[n_ops - 1] = ops[i] , ops[i] = tem;
4269 j = negs[n_ops - 1], negs[n_ops - 1] = negs[i], negs[i] = j;
4272 /* Put a non-negated operand first. If there aren't any, make all
4273 operands positive and negate the whole thing later. */
4274 for (i = 0; i < n_ops && negs[i]; i++)
4279 for (i = 0; i < n_ops; i++)
4285 tem = ops[0], ops[0] = ops[i], ops[i] = tem;
4286 j = negs[0], negs[0] = negs[i], negs[i] = j;
4289 /* Now make the result by performing the requested operations. */
4291 for (i = 1; i < n_ops; i++)
4292 result = cse_gen_binary (negs[i] ? MINUS : PLUS, mode, result, ops[i]);
4294 return negate ? gen_rtx (NEG, mode, result) : result;
4297 /* Make a binary operation by properly ordering the operands and
4298 seeing if the expression folds. */
4301 cse_gen_binary (code, mode, op0, op1)
4303 enum machine_mode mode;
4308 /* Put complex operands first and constants second if commutative. */
4309 if (GET_RTX_CLASS (code) == 'c'
4310 && ((CONSTANT_P (op0) && GET_CODE (op1) != CONST_INT)
4311 || (GET_RTX_CLASS (GET_CODE (op0)) == 'o'
4312 && GET_RTX_CLASS (GET_CODE (op1)) != 'o')
4313 || (GET_CODE (op0) == SUBREG
4314 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (op0))) == 'o'
4315 && GET_RTX_CLASS (GET_CODE (op1)) != 'o')))
4316 tem = op0, op0 = op1, op1 = tem;
4318 /* If this simplifies, do it. */
4319 tem = simplify_binary_operation (code, mode, op0, op1);
4324 /* Handle addition and subtraction of CONST_INT specially. Otherwise,
4325 just form the operation. */
4327 if (code == PLUS && GET_CODE (op1) == CONST_INT
4328 && GET_MODE (op0) != VOIDmode)
4329 return plus_constant (op0, INTVAL (op1));
4330 else if (code == MINUS && GET_CODE (op1) == CONST_INT
4331 && GET_MODE (op0) != VOIDmode)
4332 return plus_constant (op0, - INTVAL (op1));
4334 return gen_rtx (code, mode, op0, op1);
4337 /* Like simplify_binary_operation except used for relational operators.
4338 MODE is the mode of the operands, not that of the result. If MODE
4339 is VOIDmode, both operands must also be VOIDmode and we compare the
4340 operands in "infinite precision".
4342 If no simplification is possible, this function returns zero. Otherwise,
4343 it returns either const_true_rtx or const0_rtx. */
4346 simplify_relational_operation (code, mode, op0, op1)
4348 enum machine_mode mode;
4351 int equal, op0lt, op0ltu, op1lt, op1ltu;
4354 /* If op0 is a compare, extract the comparison arguments from it. */
4355 if (GET_CODE (op0) == COMPARE && op1 == const0_rtx)
4356 op1 = XEXP (op0, 1), op0 = XEXP (op0, 0);
4358 /* We can't simplify MODE_CC values since we don't know what the
4359 actual comparison is. */
4360 if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC
4367 /* For integer comparisons of A and B maybe we can simplify A - B and can
4368 then simplify a comparison of that with zero. If A and B are both either
4369 a register or a CONST_INT, this can't help; testing for these cases will
4370 prevent infinite recursion here and speed things up.
4372 If CODE is an unsigned comparison, we can only do this if A - B is a
4373 constant integer, and then we have to compare that integer with zero as a
4374 signed comparison. Note that this will give the incorrect result from
4375 comparisons that overflow. Since these are undefined, this is probably
4376 OK. If it causes a problem, we can check for A or B being an address
4377 (fp + const or SYMBOL_REF) and only do it in that case. */
4379 if (INTEGRAL_MODE_P (mode) && op1 != const0_rtx
4380 && ! ((GET_CODE (op0) == REG || GET_CODE (op0) == CONST_INT)
4381 && (GET_CODE (op1) == REG || GET_CODE (op1) == CONST_INT))
4382 && 0 != (tem = simplify_binary_operation (MINUS, mode, op0, op1))
4383 && (GET_CODE (tem) == CONST_INT
4384 || (code != GTU && code != GEU &&
4385 code != LTU && code != LEU)))
4386 return simplify_relational_operation (signed_condition (code),
4387 mode, tem, const0_rtx);
4389 /* For non-IEEE floating-point, if the two operands are equal, we know the
4391 if (rtx_equal_p (op0, op1)
4392 && (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
4393 || ! FLOAT_MODE_P (GET_MODE (op0)) || flag_fast_math))
4394 equal = 1, op0lt = 0, op0ltu = 0, op1lt = 0, op1ltu = 0;
4396 /* If the operands are floating-point constants, see if we can fold
4398 #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
4399 else if (GET_CODE (op0) == CONST_DOUBLE && GET_CODE (op1) == CONST_DOUBLE
4400 && GET_MODE_CLASS (GET_MODE (op0)) == MODE_FLOAT)
4402 REAL_VALUE_TYPE d0, d1;
4405 if (setjmp (handler))
4408 set_float_handler (handler);
4409 REAL_VALUE_FROM_CONST_DOUBLE (d0, op0);
4410 REAL_VALUE_FROM_CONST_DOUBLE (d1, op1);
4411 equal = REAL_VALUES_EQUAL (d0, d1);
4412 op0lt = op0ltu = REAL_VALUES_LESS (d0, d1);
4413 op1lt = op1ltu = REAL_VALUES_LESS (d1, d0);
4414 set_float_handler (NULL_PTR);
4416 #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
4418 /* Otherwise, see if the operands are both integers. */
4419 else if ((GET_MODE_CLASS (mode) == MODE_INT || mode == VOIDmode)
4420 && (GET_CODE (op0) == CONST_DOUBLE || GET_CODE (op0) == CONST_INT)
4421 && (GET_CODE (op1) == CONST_DOUBLE || GET_CODE (op1) == CONST_INT))
4423 int width = GET_MODE_BITSIZE (mode);
4424 HOST_WIDE_INT l0s, h0s, l1s, h1s;
4425 unsigned HOST_WIDE_INT l0u, h0u, l1u, h1u;
4427 /* Get the two words comprising each integer constant. */
4428 if (GET_CODE (op0) == CONST_DOUBLE)
4430 l0u = l0s = CONST_DOUBLE_LOW (op0);
4431 h0u = h0s = CONST_DOUBLE_HIGH (op0);
4435 l0u = l0s = INTVAL (op0);
4436 h0u = 0, h0s = l0s < 0 ? -1 : 0;
4439 if (GET_CODE (op1) == CONST_DOUBLE)
4441 l1u = l1s = CONST_DOUBLE_LOW (op1);
4442 h1u = h1s = CONST_DOUBLE_HIGH (op1);
4446 l1u = l1s = INTVAL (op1);
4447 h1u = 0, h1s = l1s < 0 ? -1 : 0;
4450 /* If WIDTH is nonzero and smaller than HOST_BITS_PER_WIDE_INT,
4451 we have to sign or zero-extend the values. */
4452 if (width != 0 && width <= HOST_BITS_PER_WIDE_INT)
4453 h0u = h1u = 0, h0s = l0s < 0 ? -1 : 0, h1s = l1s < 0 ? -1 : 0;
4455 if (width != 0 && width < HOST_BITS_PER_WIDE_INT)
4457 l0u &= ((HOST_WIDE_INT) 1 << width) - 1;
4458 l1u &= ((HOST_WIDE_INT) 1 << width) - 1;
4460 if (l0s & ((HOST_WIDE_INT) 1 << (width - 1)))
4461 l0s |= ((HOST_WIDE_INT) (-1) << width);
4463 if (l1s & ((HOST_WIDE_INT) 1 << (width - 1)))
4464 l1s |= ((HOST_WIDE_INT) (-1) << width);
4467 equal = (h0u == h1u && l0u == l1u);
4468 op0lt = (h0s < h1s || (h0s == h1s && l0s < l1s));
4469 op1lt = (h1s < h0s || (h1s == h0s && l1s < l0s));
4470 op0ltu = (h0u < h1u || (h0u == h1u && l0u < l1u));
4471 op1ltu = (h1u < h0u || (h1u == h0u && l1u < l0u));
4474 /* Otherwise, there are some code-specific tests we can make. */
4480 /* References to the frame plus a constant or labels cannot
4481 be zero, but a SYMBOL_REF can due to #pragma weak. */
4482 if (((NONZERO_BASE_PLUS_P (op0) && op1 == const0_rtx)
4483 || GET_CODE (op0) == LABEL_REF)
4484 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4485 /* On some machines, the ap reg can be 0 sometimes. */
4486 && op0 != arg_pointer_rtx
4493 if (((NONZERO_BASE_PLUS_P (op0) && op1 == const0_rtx)
4494 || GET_CODE (op0) == LABEL_REF)
4495 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4496 && op0 != arg_pointer_rtx
4499 return const_true_rtx;
4503 /* Unsigned values are never negative. */
4504 if (op1 == const0_rtx)
4505 return const_true_rtx;
4509 if (op1 == const0_rtx)
4514 /* Unsigned values are never greater than the largest
4516 if (GET_CODE (op1) == CONST_INT
4517 && INTVAL (op1) == GET_MODE_MASK (mode)
4518 && INTEGRAL_MODE_P (mode))
4519 return const_true_rtx;
4523 if (GET_CODE (op1) == CONST_INT
4524 && INTVAL (op1) == GET_MODE_MASK (mode)
4525 && INTEGRAL_MODE_P (mode))
4533 /* If we reach here, EQUAL, OP0LT, OP0LTU, OP1LT, and OP1LTU are set
4538 return equal ? const_true_rtx : const0_rtx;
4540 return ! equal ? const_true_rtx : const0_rtx;
4542 return op0lt ? const_true_rtx : const0_rtx;
4544 return op1lt ? const_true_rtx : const0_rtx;
4546 return op0ltu ? const_true_rtx : const0_rtx;
4548 return op1ltu ? const_true_rtx : const0_rtx;
4550 return equal || op0lt ? const_true_rtx : const0_rtx;
4552 return equal || op1lt ? const_true_rtx : const0_rtx;
4554 return equal || op0ltu ? const_true_rtx : const0_rtx;
4556 return equal || op1ltu ? const_true_rtx : const0_rtx;
4562 /* Simplify CODE, an operation with result mode MODE and three operands,
4563 OP0, OP1, and OP2. OP0_MODE was the mode of OP0 before it became
4564 a constant. Return 0 if no simplifications is possible. */
4567 simplify_ternary_operation (code, mode, op0_mode, op0, op1, op2)
4569 enum machine_mode mode, op0_mode;
4572 int width = GET_MODE_BITSIZE (mode);
4574 /* VOIDmode means "infinite" precision. */
4576 width = HOST_BITS_PER_WIDE_INT;
4582 if (GET_CODE (op0) == CONST_INT
4583 && GET_CODE (op1) == CONST_INT
4584 && GET_CODE (op2) == CONST_INT
4585 && INTVAL (op1) + INTVAL (op2) <= GET_MODE_BITSIZE (op0_mode)
4586 && width <= HOST_BITS_PER_WIDE_INT)
4588 /* Extracting a bit-field from a constant */
4589 HOST_WIDE_INT val = INTVAL (op0);
4592 val >>= (GET_MODE_BITSIZE (op0_mode) - INTVAL (op2) - INTVAL (op1));
4594 val >>= INTVAL (op2);
4596 if (HOST_BITS_PER_WIDE_INT != INTVAL (op1))
4598 /* First zero-extend. */
4599 val &= ((HOST_WIDE_INT) 1 << INTVAL (op1)) - 1;
4600 /* If desired, propagate sign bit. */
4601 if (code == SIGN_EXTRACT
4602 && (val & ((HOST_WIDE_INT) 1 << (INTVAL (op1) - 1))))
4603 val |= ~ (((HOST_WIDE_INT) 1 << INTVAL (op1)) - 1);
4606 /* Clear the bits that don't belong in our mode,
4607 unless they and our sign bit are all one.
4608 So we get either a reasonable negative value or a reasonable
4609 unsigned value for this mode. */
4610 if (width < HOST_BITS_PER_WIDE_INT
4611 && ((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
4612 != ((HOST_WIDE_INT) (-1) << (width - 1))))
4613 val &= ((HOST_WIDE_INT) 1 << width) - 1;
4615 return GEN_INT (val);
4620 if (GET_CODE (op0) == CONST_INT)
4621 return op0 != const0_rtx ? op1 : op2;
4631 /* If X is a nontrivial arithmetic operation on an argument
4632 for which a constant value can be determined, return
4633 the result of operating on that value, as a constant.
4634 Otherwise, return X, possibly with one or more operands
4635 modified by recursive calls to this function.
4637 If X is a register whose contents are known, we do NOT
4638 return those contents here. equiv_constant is called to
4641 INSN is the insn that we may be modifying. If it is 0, make a copy
4642 of X before modifying it. */
4649 register enum rtx_code code;
4650 register enum machine_mode mode;
4657 /* Folded equivalents of first two operands of X. */
4661 /* Constant equivalents of first three operands of X;
4662 0 when no such equivalent is known. */
4667 /* The mode of the first operand of X. We need this for sign and zero
4669 enum machine_mode mode_arg0;
4674 mode = GET_MODE (x);
4675 code = GET_CODE (x);
4684 /* No use simplifying an EXPR_LIST
4685 since they are used only for lists of args
4686 in a function call's REG_EQUAL note. */
4692 return prev_insn_cc0;
4696 /* If the next insn is a CODE_LABEL followed by a jump table,
4697 PC's value is a LABEL_REF pointing to that label. That
4698 lets us fold switch statements on the Vax. */
4699 if (insn && GET_CODE (insn) == JUMP_INSN)
4701 rtx next = next_nonnote_insn (insn);
4703 if (next && GET_CODE (next) == CODE_LABEL
4704 && NEXT_INSN (next) != 0
4705 && GET_CODE (NEXT_INSN (next)) == JUMP_INSN
4706 && (GET_CODE (PATTERN (NEXT_INSN (next))) == ADDR_VEC
4707 || GET_CODE (PATTERN (NEXT_INSN (next))) == ADDR_DIFF_VEC))
4708 return gen_rtx (LABEL_REF, Pmode, next);
4713 /* See if we previously assigned a constant value to this SUBREG. */
4714 if ((new = lookup_as_function (x, CONST_INT)) != 0
4715 || (new = lookup_as_function (x, CONST_DOUBLE)) != 0)
4718 /* If this is a paradoxical SUBREG, we have no idea what value the
4719 extra bits would have. However, if the operand is equivalent
4720 to a SUBREG whose operand is the same as our mode, and all the
4721 modes are within a word, we can just use the inner operand
4722 because these SUBREGs just say how to treat the register.
4724 Similarly if we find an integer constant. */
4726 if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
4728 enum machine_mode imode = GET_MODE (SUBREG_REG (x));
4729 struct table_elt *elt;
4731 if (GET_MODE_SIZE (mode) <= UNITS_PER_WORD
4732 && GET_MODE_SIZE (imode) <= UNITS_PER_WORD
4733 && (elt = lookup (SUBREG_REG (x), HASH (SUBREG_REG (x), imode),
4735 for (elt = elt->first_same_value;
4736 elt; elt = elt->next_same_value)
4738 if (CONSTANT_P (elt->exp)
4739 && GET_MODE (elt->exp) == VOIDmode)
4742 if (GET_CODE (elt->exp) == SUBREG
4743 && GET_MODE (SUBREG_REG (elt->exp)) == mode
4744 && exp_equiv_p (elt->exp, elt->exp, 1, 0))
4745 return copy_rtx (SUBREG_REG (elt->exp));
4751 /* Fold SUBREG_REG. If it changed, see if we can simplify the SUBREG.
4752 We might be able to if the SUBREG is extracting a single word in an
4753 integral mode or extracting the low part. */
4755 folded_arg0 = fold_rtx (SUBREG_REG (x), insn);
4756 const_arg0 = equiv_constant (folded_arg0);
4758 folded_arg0 = const_arg0;
4760 if (folded_arg0 != SUBREG_REG (x))
4764 if (GET_MODE_CLASS (mode) == MODE_INT
4765 && GET_MODE_SIZE (mode) == UNITS_PER_WORD
4766 && GET_MODE (SUBREG_REG (x)) != VOIDmode)
4767 new = operand_subword (folded_arg0, SUBREG_WORD (x), 0,
4768 GET_MODE (SUBREG_REG (x)));
4769 if (new == 0 && subreg_lowpart_p (x))
4770 new = gen_lowpart_if_possible (mode, folded_arg0);
4775 /* If this is a narrowing SUBREG and our operand is a REG, see if
4776 we can find an equivalence for REG that is an arithmetic operation
4777 in a wider mode where both operands are paradoxical SUBREGs
4778 from objects of our result mode. In that case, we couldn't report
4779 an equivalent value for that operation, since we don't know what the
4780 extra bits will be. But we can find an equivalence for this SUBREG
4781 by folding that operation is the narrow mode. This allows us to
4782 fold arithmetic in narrow modes when the machine only supports
4783 word-sized arithmetic.
4785 Also look for a case where we have a SUBREG whose operand is the
4786 same as our result. If both modes are smaller than a word, we
4787 are simply interpreting a register in different modes and we
4788 can use the inner value. */
4790 if (GET_CODE (folded_arg0) == REG
4791 && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (folded_arg0))
4792 && subreg_lowpart_p (x))
4794 struct table_elt *elt;
4796 /* We can use HASH here since we know that canon_hash won't be
4798 elt = lookup (folded_arg0,
4799 HASH (folded_arg0, GET_MODE (folded_arg0)),
4800 GET_MODE (folded_arg0));
4803 elt = elt->first_same_value;
4805 for (; elt; elt = elt->next_same_value)
4807 enum rtx_code eltcode = GET_CODE (elt->exp);
4809 /* Just check for unary and binary operations. */
4810 if (GET_RTX_CLASS (GET_CODE (elt->exp)) == '1'
4811 && GET_CODE (elt->exp) != SIGN_EXTEND
4812 && GET_CODE (elt->exp) != ZERO_EXTEND
4813 && GET_CODE (XEXP (elt->exp, 0)) == SUBREG
4814 && GET_MODE (SUBREG_REG (XEXP (elt->exp, 0))) == mode)
4816 rtx op0 = SUBREG_REG (XEXP (elt->exp, 0));
4818 if (GET_CODE (op0) != REG && ! CONSTANT_P (op0))
4819 op0 = fold_rtx (op0, NULL_RTX);
4821 op0 = equiv_constant (op0);
4823 new = simplify_unary_operation (GET_CODE (elt->exp), mode,
4826 else if ((GET_RTX_CLASS (GET_CODE (elt->exp)) == '2'
4827 || GET_RTX_CLASS (GET_CODE (elt->exp)) == 'c')
4828 && eltcode != DIV && eltcode != MOD
4829 && eltcode != UDIV && eltcode != UMOD
4830 && eltcode != ASHIFTRT && eltcode != LSHIFTRT
4831 && eltcode != ROTATE && eltcode != ROTATERT
4832 && ((GET_CODE (XEXP (elt->exp, 0)) == SUBREG
4833 && (GET_MODE (SUBREG_REG (XEXP (elt->exp, 0)))
4835 || CONSTANT_P (XEXP (elt->exp, 0)))
4836 && ((GET_CODE (XEXP (elt->exp, 1)) == SUBREG
4837 && (GET_MODE (SUBREG_REG (XEXP (elt->exp, 1)))
4839 || CONSTANT_P (XEXP (elt->exp, 1))))
4841 rtx op0 = gen_lowpart_common (mode, XEXP (elt->exp, 0));
4842 rtx op1 = gen_lowpart_common (mode, XEXP (elt->exp, 1));
4844 if (op0 && GET_CODE (op0) != REG && ! CONSTANT_P (op0))
4845 op0 = fold_rtx (op0, NULL_RTX);
4848 op0 = equiv_constant (op0);
4850 if (op1 && GET_CODE (op1) != REG && ! CONSTANT_P (op1))
4851 op1 = fold_rtx (op1, NULL_RTX);
4854 op1 = equiv_constant (op1);
4856 /* If we are looking for the low SImode part of
4857 (ashift:DI c (const_int 32)), it doesn't work
4858 to compute that in SImode, because a 32-bit shift
4859 in SImode is unpredictable. We know the value is 0. */
4861 && GET_CODE (elt->exp) == ASHIFT
4862 && GET_CODE (op1) == CONST_INT
4863 && INTVAL (op1) >= GET_MODE_BITSIZE (mode))
4865 if (INTVAL (op1) < GET_MODE_BITSIZE (GET_MODE (elt->exp)))
4867 /* If the count fits in the inner mode's width,
4868 but exceeds the outer mode's width,
4869 the value will get truncated to 0
4873 /* If the count exceeds even the inner mode's width,
4874 don't fold this expression. */
4877 else if (op0 && op1)
4878 new = simplify_binary_operation (GET_CODE (elt->exp), mode,
4882 else if (GET_CODE (elt->exp) == SUBREG
4883 && GET_MODE (SUBREG_REG (elt->exp)) == mode
4884 && (GET_MODE_SIZE (GET_MODE (folded_arg0))
4886 && exp_equiv_p (elt->exp, elt->exp, 1, 0))
4887 new = copy_rtx (SUBREG_REG (elt->exp));
4898 /* If we have (NOT Y), see if Y is known to be (NOT Z).
4899 If so, (NOT Y) simplifies to Z. Similarly for NEG. */
4900 new = lookup_as_function (XEXP (x, 0), code);
4902 return fold_rtx (copy_rtx (XEXP (new, 0)), insn);
4906 /* If we are not actually processing an insn, don't try to find the
4907 best address. Not only don't we care, but we could modify the
4908 MEM in an invalid way since we have no insn to validate against. */
4910 find_best_addr (insn, &XEXP (x, 0));
4913 /* Even if we don't fold in the insn itself,
4914 we can safely do so here, in hopes of getting a constant. */
4915 rtx addr = fold_rtx (XEXP (x, 0), NULL_RTX);
4917 HOST_WIDE_INT offset = 0;
4919 if (GET_CODE (addr) == REG
4920 && REGNO_QTY_VALID_P (REGNO (addr))
4921 && GET_MODE (addr) == qty_mode[reg_qty[REGNO (addr)]]
4922 && qty_const[reg_qty[REGNO (addr)]] != 0)
4923 addr = qty_const[reg_qty[REGNO (addr)]];
4925 /* If address is constant, split it into a base and integer offset. */
4926 if (GET_CODE (addr) == SYMBOL_REF || GET_CODE (addr) == LABEL_REF)
4928 else if (GET_CODE (addr) == CONST && GET_CODE (XEXP (addr, 0)) == PLUS
4929 && GET_CODE (XEXP (XEXP (addr, 0), 1)) == CONST_INT)
4931 base = XEXP (XEXP (addr, 0), 0);
4932 offset = INTVAL (XEXP (XEXP (addr, 0), 1));
4934 else if (GET_CODE (addr) == LO_SUM
4935 && GET_CODE (XEXP (addr, 1)) == SYMBOL_REF)
4936 base = XEXP (addr, 1);
4938 /* If this is a constant pool reference, we can fold it into its
4939 constant to allow better value tracking. */
4940 if (base && GET_CODE (base) == SYMBOL_REF
4941 && CONSTANT_POOL_ADDRESS_P (base))
4943 rtx constant = get_pool_constant (base);
4944 enum machine_mode const_mode = get_pool_mode (base);
4947 if (CONSTANT_P (constant) && GET_CODE (constant) != CONST_INT)
4948 constant_pool_entries_cost = COST (constant);
4950 /* If we are loading the full constant, we have an equivalence. */
4951 if (offset == 0 && mode == const_mode)
4954 /* If this actually isn't a constant (wierd!), we can't do
4955 anything. Otherwise, handle the two most common cases:
4956 extracting a word from a multi-word constant, and extracting
4957 the low-order bits. Other cases don't seem common enough to
4959 if (! CONSTANT_P (constant))
4962 if (GET_MODE_CLASS (mode) == MODE_INT
4963 && GET_MODE_SIZE (mode) == UNITS_PER_WORD
4964 && offset % UNITS_PER_WORD == 0
4965 && (new = operand_subword (constant,
4966 offset / UNITS_PER_WORD,
4967 0, const_mode)) != 0)
4970 if (((BYTES_BIG_ENDIAN
4971 && offset == GET_MODE_SIZE (GET_MODE (constant)) - 1)
4972 || (! BYTES_BIG_ENDIAN && offset == 0))
4973 && (new = gen_lowpart_if_possible (mode, constant)) != 0)
4977 /* If this is a reference to a label at a known position in a jump
4978 table, we also know its value. */
4979 if (base && GET_CODE (base) == LABEL_REF)
4981 rtx label = XEXP (base, 0);
4982 rtx table_insn = NEXT_INSN (label);
4984 if (table_insn && GET_CODE (table_insn) == JUMP_INSN
4985 && GET_CODE (PATTERN (table_insn)) == ADDR_VEC)
4987 rtx table = PATTERN (table_insn);
4990 && (offset / GET_MODE_SIZE (GET_MODE (table))
4991 < XVECLEN (table, 0)))
4992 return XVECEXP (table, 0,
4993 offset / GET_MODE_SIZE (GET_MODE (table)));
4995 if (table_insn && GET_CODE (table_insn) == JUMP_INSN
4996 && GET_CODE (PATTERN (table_insn)) == ADDR_DIFF_VEC)
4998 rtx table = PATTERN (table_insn);
5001 && (offset / GET_MODE_SIZE (GET_MODE (table))
5002 < XVECLEN (table, 1)))
5004 offset /= GET_MODE_SIZE (GET_MODE (table));
5005 new = gen_rtx (MINUS, Pmode, XVECEXP (table, 1, offset),
5008 if (GET_MODE (table) != Pmode)
5009 new = gen_rtx (TRUNCATE, GET_MODE (table), new);
5011 /* Indicate this is a constant. This isn't a
5012 valid form of CONST, but it will only be used
5013 to fold the next insns and then discarded, so
5014 it should be safe. */
5015 return gen_rtx (CONST, GET_MODE (new), new);
5027 mode_arg0 = VOIDmode;
5029 /* Try folding our operands.
5030 Then see which ones have constant values known. */
5032 fmt = GET_RTX_FORMAT (code);
5033 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5036 rtx arg = XEXP (x, i);
5037 rtx folded_arg = arg, const_arg = 0;
5038 enum machine_mode mode_arg = GET_MODE (arg);
5039 rtx cheap_arg, expensive_arg;
5040 rtx replacements[2];
5043 /* Most arguments are cheap, so handle them specially. */
5044 switch (GET_CODE (arg))
5047 /* This is the same as calling equiv_constant; it is duplicated
5049 if (REGNO_QTY_VALID_P (REGNO (arg))
5050 && qty_const[reg_qty[REGNO (arg)]] != 0
5051 && GET_CODE (qty_const[reg_qty[REGNO (arg)]]) != REG
5052 && GET_CODE (qty_const[reg_qty[REGNO (arg)]]) != PLUS)
5054 = gen_lowpart_if_possible (GET_MODE (arg),
5055 qty_const[reg_qty[REGNO (arg)]]);
5068 folded_arg = prev_insn_cc0;
5069 mode_arg = prev_insn_cc0_mode;
5070 const_arg = equiv_constant (folded_arg);
5075 folded_arg = fold_rtx (arg, insn);
5076 const_arg = equiv_constant (folded_arg);
5079 /* For the first three operands, see if the operand
5080 is constant or equivalent to a constant. */
5084 folded_arg0 = folded_arg;
5085 const_arg0 = const_arg;
5086 mode_arg0 = mode_arg;
5089 folded_arg1 = folded_arg;
5090 const_arg1 = const_arg;
5093 const_arg2 = const_arg;
5097 /* Pick the least expensive of the folded argument and an
5098 equivalent constant argument. */
5099 if (const_arg == 0 || const_arg == folded_arg
5100 || COST (const_arg) > COST (folded_arg))
5101 cheap_arg = folded_arg, expensive_arg = const_arg;
5103 cheap_arg = const_arg, expensive_arg = folded_arg;
5105 /* Try to replace the operand with the cheapest of the two
5106 possibilities. If it doesn't work and this is either of the first
5107 two operands of a commutative operation, try swapping them.
5108 If THAT fails, try the more expensive, provided it is cheaper
5109 than what is already there. */
5111 if (cheap_arg == XEXP (x, i))
5114 if (insn == 0 && ! copied)
5120 replacements[0] = cheap_arg, replacements[1] = expensive_arg;
5122 j < 2 && replacements[j]
5123 && COST (replacements[j]) < COST (XEXP (x, i));
5126 if (validate_change (insn, &XEXP (x, i), replacements[j], 0))
5129 if (code == NE || code == EQ || GET_RTX_CLASS (code) == 'c')
5131 validate_change (insn, &XEXP (x, i), XEXP (x, 1 - i), 1);
5132 validate_change (insn, &XEXP (x, 1 - i), replacements[j], 1);
5134 if (apply_change_group ())
5136 /* Swap them back to be invalid so that this loop can
5137 continue and flag them to be swapped back later. */
5140 tem = XEXP (x, 0); XEXP (x, 0) = XEXP (x, 1);
5149 else if (fmt[i] == 'E')
5150 /* Don't try to fold inside of a vector of expressions.
5151 Doing nothing is harmless. */
5154 /* If a commutative operation, place a constant integer as the second
5155 operand unless the first operand is also a constant integer. Otherwise,
5156 place any constant second unless the first operand is also a constant. */
5158 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
5160 if (must_swap || (const_arg0
5162 || (GET_CODE (const_arg0) == CONST_INT
5163 && GET_CODE (const_arg1) != CONST_INT))))
5165 register rtx tem = XEXP (x, 0);
5167 if (insn == 0 && ! copied)
5173 validate_change (insn, &XEXP (x, 0), XEXP (x, 1), 1);
5174 validate_change (insn, &XEXP (x, 1), tem, 1);
5175 if (apply_change_group ())
5177 tem = const_arg0, const_arg0 = const_arg1, const_arg1 = tem;
5178 tem = folded_arg0, folded_arg0 = folded_arg1, folded_arg1 = tem;
5183 /* If X is an arithmetic operation, see if we can simplify it. */
5185 switch (GET_RTX_CLASS (code))
5191 /* We can't simplify extension ops unless we know the
5193 if ((code == ZERO_EXTEND || code == SIGN_EXTEND)
5194 && mode_arg0 == VOIDmode)
5197 /* If we had a CONST, strip it off and put it back later if we
5199 if (const_arg0 != 0 && GET_CODE (const_arg0) == CONST)
5200 is_const = 1, const_arg0 = XEXP (const_arg0, 0);
5202 new = simplify_unary_operation (code, mode,
5203 const_arg0 ? const_arg0 : folded_arg0,
5205 if (new != 0 && is_const)
5206 new = gen_rtx (CONST, mode, new);
5211 /* See what items are actually being compared and set FOLDED_ARG[01]
5212 to those values and CODE to the actual comparison code. If any are
5213 constant, set CONST_ARG0 and CONST_ARG1 appropriately. We needn't
5214 do anything if both operands are already known to be constant. */
5216 if (const_arg0 == 0 || const_arg1 == 0)
5218 struct table_elt *p0, *p1;
5219 rtx true = const_true_rtx, false = const0_rtx;
5220 enum machine_mode mode_arg1;
5222 #ifdef FLOAT_STORE_FLAG_VALUE
5223 if (GET_MODE_CLASS (mode) == MODE_FLOAT)
5225 true = CONST_DOUBLE_FROM_REAL_VALUE (FLOAT_STORE_FLAG_VALUE,
5227 false = CONST0_RTX (mode);
5231 code = find_comparison_args (code, &folded_arg0, &folded_arg1,
5232 &mode_arg0, &mode_arg1);
5233 const_arg0 = equiv_constant (folded_arg0);
5234 const_arg1 = equiv_constant (folded_arg1);
5236 /* If the mode is VOIDmode or a MODE_CC mode, we don't know
5237 what kinds of things are being compared, so we can't do
5238 anything with this comparison. */
5240 if (mode_arg0 == VOIDmode || GET_MODE_CLASS (mode_arg0) == MODE_CC)
5243 /* If we do not now have two constants being compared, see if we
5244 can nevertheless deduce some things about the comparison. */
5245 if (const_arg0 == 0 || const_arg1 == 0)
5247 /* Is FOLDED_ARG0 frame-pointer plus a constant? Or non-explicit
5248 constant? These aren't zero, but we don't know their sign. */
5249 if (const_arg1 == const0_rtx
5250 && (NONZERO_BASE_PLUS_P (folded_arg0)
5251 #if 0 /* Sad to say, on sysvr4, #pragma weak can make a symbol address
5253 || GET_CODE (folded_arg0) == SYMBOL_REF
5255 || GET_CODE (folded_arg0) == LABEL_REF
5256 || GET_CODE (folded_arg0) == CONST))
5260 else if (code == NE)
5264 /* See if the two operands are the same. We don't do this
5265 for IEEE floating-point since we can't assume x == x
5266 since x might be a NaN. */
5268 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
5269 || ! FLOAT_MODE_P (mode_arg0) || flag_fast_math)
5270 && (folded_arg0 == folded_arg1
5271 || (GET_CODE (folded_arg0) == REG
5272 && GET_CODE (folded_arg1) == REG
5273 && (reg_qty[REGNO (folded_arg0)]
5274 == reg_qty[REGNO (folded_arg1)]))
5275 || ((p0 = lookup (folded_arg0,
5276 (safe_hash (folded_arg0, mode_arg0)
5277 % NBUCKETS), mode_arg0))
5278 && (p1 = lookup (folded_arg1,
5279 (safe_hash (folded_arg1, mode_arg0)
5280 % NBUCKETS), mode_arg0))
5281 && p0->first_same_value == p1->first_same_value)))
5282 return ((code == EQ || code == LE || code == GE
5283 || code == LEU || code == GEU)
5286 /* If FOLDED_ARG0 is a register, see if the comparison we are
5287 doing now is either the same as we did before or the reverse
5288 (we only check the reverse if not floating-point). */
5289 else if (GET_CODE (folded_arg0) == REG)
5291 int qty = reg_qty[REGNO (folded_arg0)];
5293 if (REGNO_QTY_VALID_P (REGNO (folded_arg0))
5294 && (comparison_dominates_p (qty_comparison_code[qty], code)
5295 || (comparison_dominates_p (qty_comparison_code[qty],
5296 reverse_condition (code))
5297 && ! FLOAT_MODE_P (mode_arg0)))
5298 && (rtx_equal_p (qty_comparison_const[qty], folded_arg1)
5300 && rtx_equal_p (qty_comparison_const[qty],
5302 || (GET_CODE (folded_arg1) == REG
5303 && (reg_qty[REGNO (folded_arg1)]
5304 == qty_comparison_qty[qty]))))
5305 return (comparison_dominates_p (qty_comparison_code[qty],
5312 /* If we are comparing against zero, see if the first operand is
5313 equivalent to an IOR with a constant. If so, we may be able to
5314 determine the result of this comparison. */
5316 if (const_arg1 == const0_rtx)
5318 rtx y = lookup_as_function (folded_arg0, IOR);
5322 && (inner_const = equiv_constant (XEXP (y, 1))) != 0
5323 && GET_CODE (inner_const) == CONST_INT
5324 && INTVAL (inner_const) != 0)
5326 int sign_bitnum = GET_MODE_BITSIZE (mode_arg0) - 1;
5327 int has_sign = (HOST_BITS_PER_WIDE_INT >= sign_bitnum
5328 && (INTVAL (inner_const)
5329 & ((HOST_WIDE_INT) 1 << sign_bitnum)));
5330 rtx true = const_true_rtx, false = const0_rtx;
5332 #ifdef FLOAT_STORE_FLAG_VALUE
5333 if (GET_MODE_CLASS (mode) == MODE_FLOAT)
5335 true = CONST_DOUBLE_FROM_REAL_VALUE (FLOAT_STORE_FLAG_VALUE,
5337 false = CONST0_RTX (mode);
5359 new = simplify_relational_operation (code, mode_arg0,
5360 const_arg0 ? const_arg0 : folded_arg0,
5361 const_arg1 ? const_arg1 : folded_arg1);
5362 #ifdef FLOAT_STORE_FLAG_VALUE
5363 if (new != 0 && GET_MODE_CLASS (mode) == MODE_FLOAT)
5364 new = ((new == const0_rtx) ? CONST0_RTX (mode)
5365 : CONST_DOUBLE_FROM_REAL_VALUE (FLOAT_STORE_FLAG_VALUE, mode));
5374 /* If the second operand is a LABEL_REF, see if the first is a MINUS
5375 with that LABEL_REF as its second operand. If so, the result is
5376 the first operand of that MINUS. This handles switches with an
5377 ADDR_DIFF_VEC table. */
5378 if (const_arg1 && GET_CODE (const_arg1) == LABEL_REF)
5381 = GET_CODE (folded_arg0) == MINUS ? folded_arg0
5382 : lookup_as_function (folded_arg0, MINUS);
5384 if (y != 0 && GET_CODE (XEXP (y, 1)) == LABEL_REF
5385 && XEXP (XEXP (y, 1), 0) == XEXP (const_arg1, 0))
5388 /* Now try for a CONST of a MINUS like the above. */
5389 if ((y = (GET_CODE (folded_arg0) == CONST ? folded_arg0
5390 : lookup_as_function (folded_arg0, CONST))) != 0
5391 && GET_CODE (XEXP (y, 0)) == MINUS
5392 && GET_CODE (XEXP (XEXP (y, 0), 1)) == LABEL_REF
5393 && XEXP (XEXP (XEXP (y, 0),1), 0) == XEXP (const_arg1, 0))
5394 return XEXP (XEXP (y, 0), 0);
5397 /* Likewise if the operands are in the other order. */
5398 if (const_arg0 && GET_CODE (const_arg0) == LABEL_REF)
5401 = GET_CODE (folded_arg1) == MINUS ? folded_arg1
5402 : lookup_as_function (folded_arg1, MINUS);
5404 if (y != 0 && GET_CODE (XEXP (y, 1)) == LABEL_REF
5405 && XEXP (XEXP (y, 1), 0) == XEXP (const_arg0, 0))
5408 /* Now try for a CONST of a MINUS like the above. */
5409 if ((y = (GET_CODE (folded_arg1) == CONST ? folded_arg1
5410 : lookup_as_function (folded_arg1, CONST))) != 0
5411 && GET_CODE (XEXP (y, 0)) == MINUS
5412 && GET_CODE (XEXP (XEXP (y, 0), 1)) == LABEL_REF
5413 && XEXP (XEXP (XEXP (y, 0),1), 0) == XEXP (const_arg0, 0))
5414 return XEXP (XEXP (y, 0), 0);
5417 /* If second operand is a register equivalent to a negative
5418 CONST_INT, see if we can find a register equivalent to the
5419 positive constant. Make a MINUS if so. Don't do this for
5420 a negative constant since we might then alternate between
5421 chosing positive and negative constants. Having the positive
5422 constant previously-used is the more common case. */
5423 if (const_arg1 && GET_CODE (const_arg1) == CONST_INT
5424 && INTVAL (const_arg1) < 0 && GET_CODE (folded_arg1) == REG)
5426 rtx new_const = GEN_INT (- INTVAL (const_arg1));
5428 = lookup (new_const, safe_hash (new_const, mode) % NBUCKETS,
5432 for (p = p->first_same_value; p; p = p->next_same_value)
5433 if (GET_CODE (p->exp) == REG)
5434 return cse_gen_binary (MINUS, mode, folded_arg0,
5435 canon_reg (p->exp, NULL_RTX));
5440 /* If we have (MINUS Y C), see if Y is known to be (PLUS Z C2).
5441 If so, produce (PLUS Z C2-C). */
5442 if (const_arg1 != 0 && GET_CODE (const_arg1) == CONST_INT)
5444 rtx y = lookup_as_function (XEXP (x, 0), PLUS);
5445 if (y && GET_CODE (XEXP (y, 1)) == CONST_INT)
5446 return fold_rtx (plus_constant (copy_rtx (y),
5447 -INTVAL (const_arg1)),
5451 /* ... fall through ... */
5454 case SMIN: case SMAX: case UMIN: case UMAX:
5455 case IOR: case AND: case XOR:
5456 case MULT: case DIV: case UDIV:
5457 case ASHIFT: case LSHIFTRT: case ASHIFTRT:
5458 /* If we have (<op> <reg> <const_int>) for an associative OP and REG
5459 is known to be of similar form, we may be able to replace the
5460 operation with a combined operation. This may eliminate the
5461 intermediate operation if every use is simplified in this way.
5462 Note that the similar optimization done by combine.c only works
5463 if the intermediate operation's result has only one reference. */
5465 if (GET_CODE (folded_arg0) == REG
5466 && const_arg1 && GET_CODE (const_arg1) == CONST_INT)
5469 = (code == ASHIFT || code == ASHIFTRT || code == LSHIFTRT);
5470 rtx y = lookup_as_function (folded_arg0, code);
5472 enum rtx_code associate_code;
5476 || 0 == (inner_const
5477 = equiv_constant (fold_rtx (XEXP (y, 1), 0)))
5478 || GET_CODE (inner_const) != CONST_INT
5479 /* If we have compiled a statement like
5480 "if (x == (x & mask1))", and now are looking at
5481 "x & mask2", we will have a case where the first operand
5482 of Y is the same as our first operand. Unless we detect
5483 this case, an infinite loop will result. */
5484 || XEXP (y, 0) == folded_arg0)
5487 /* Don't associate these operations if they are a PLUS with the
5488 same constant and it is a power of two. These might be doable
5489 with a pre- or post-increment. Similarly for two subtracts of
5490 identical powers of two with post decrement. */
5492 if (code == PLUS && INTVAL (const_arg1) == INTVAL (inner_const)
5494 #if defined(HAVE_PRE_INCREMENT) || defined(HAVE_POST_INCREMENT)
5495 || exact_log2 (INTVAL (const_arg1)) >= 0
5497 #if defined(HAVE_PRE_DECREMENT) || defined(HAVE_POST_DECREMENT)
5498 || exact_log2 (- INTVAL (const_arg1)) >= 0
5503 /* Compute the code used to compose the constants. For example,
5504 A/C1/C2 is A/(C1 * C2), so if CODE == DIV, we want MULT. */
5507 = (code == MULT || code == DIV || code == UDIV ? MULT
5508 : is_shift || code == PLUS || code == MINUS ? PLUS : code);
5510 new_const = simplify_binary_operation (associate_code, mode,
5511 const_arg1, inner_const);
5516 /* If we are associating shift operations, don't let this
5517 produce a shift of the size of the object or larger.
5518 This could occur when we follow a sign-extend by a right
5519 shift on a machine that does a sign-extend as a pair
5522 if (is_shift && GET_CODE (new_const) == CONST_INT
5523 && INTVAL (new_const) >= GET_MODE_BITSIZE (mode))
5525 /* As an exception, we can turn an ASHIFTRT of this
5526 form into a shift of the number of bits - 1. */
5527 if (code == ASHIFTRT)
5528 new_const = GEN_INT (GET_MODE_BITSIZE (mode) - 1);
5533 y = copy_rtx (XEXP (y, 0));
5535 /* If Y contains our first operand (the most common way this
5536 can happen is if Y is a MEM), we would do into an infinite
5537 loop if we tried to fold it. So don't in that case. */
5539 if (! reg_mentioned_p (folded_arg0, y))
5540 y = fold_rtx (y, insn);
5542 return cse_gen_binary (code, mode, y, new_const);
5546 new = simplify_binary_operation (code, mode,
5547 const_arg0 ? const_arg0 : folded_arg0,
5548 const_arg1 ? const_arg1 : folded_arg1);
5552 /* (lo_sum (high X) X) is simply X. */
5553 if (code == LO_SUM && const_arg0 != 0
5554 && GET_CODE (const_arg0) == HIGH
5555 && rtx_equal_p (XEXP (const_arg0, 0), const_arg1))
5561 new = simplify_ternary_operation (code, mode, mode_arg0,
5562 const_arg0 ? const_arg0 : folded_arg0,
5563 const_arg1 ? const_arg1 : folded_arg1,
5564 const_arg2 ? const_arg2 : XEXP (x, 2));
5568 return new ? new : x;
5571 /* Return a constant value currently equivalent to X.
5572 Return 0 if we don't know one. */
5578 if (GET_CODE (x) == REG
5579 && REGNO_QTY_VALID_P (REGNO (x))
5580 && qty_const[reg_qty[REGNO (x)]])
5581 x = gen_lowpart_if_possible (GET_MODE (x), qty_const[reg_qty[REGNO (x)]]);
5583 if (x != 0 && CONSTANT_P (x))
5586 /* If X is a MEM, try to fold it outside the context of any insn to see if
5587 it might be equivalent to a constant. That handles the case where it
5588 is a constant-pool reference. Then try to look it up in the hash table
5589 in case it is something whose value we have seen before. */
5591 if (GET_CODE (x) == MEM)
5593 struct table_elt *elt;
5595 x = fold_rtx (x, NULL_RTX);
5599 elt = lookup (x, safe_hash (x, GET_MODE (x)) % NBUCKETS, GET_MODE (x));
5603 for (elt = elt->first_same_value; elt; elt = elt->next_same_value)
5604 if (elt->is_const && CONSTANT_P (elt->exp))
5611 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point
5612 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the
5613 least-significant part of X.
5614 MODE specifies how big a part of X to return.
5616 If the requested operation cannot be done, 0 is returned.
5618 This is similar to gen_lowpart in emit-rtl.c. */
5621 gen_lowpart_if_possible (mode, x)
5622 enum machine_mode mode;
5625 rtx result = gen_lowpart_common (mode, x);
5629 else if (GET_CODE (x) == MEM)
5631 /* This is the only other case we handle. */
5632 register int offset = 0;
5635 #if WORDS_BIG_ENDIAN
5636 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
5637 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
5639 #if BYTES_BIG_ENDIAN
5640 /* Adjust the address so that the address-after-the-data
5642 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
5643 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
5645 new = gen_rtx (MEM, mode, plus_constant (XEXP (x, 0), offset));
5646 if (! memory_address_p (mode, XEXP (new, 0)))
5648 MEM_VOLATILE_P (new) = MEM_VOLATILE_P (x);
5649 RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (x);
5650 MEM_IN_STRUCT_P (new) = MEM_IN_STRUCT_P (x);
5657 /* Given INSN, a jump insn, TAKEN indicates if we are following the "taken"
5658 branch. It will be zero if not.
5660 In certain cases, this can cause us to add an equivalence. For example,
5661 if we are following the taken case of
5663 we can add the fact that `i' and '2' are now equivalent.
5665 In any case, we can record that this comparison was passed. If the same
5666 comparison is seen later, we will know its value. */
5669 record_jump_equiv (insn, taken)
5673 int cond_known_true;
5675 enum machine_mode mode, mode0, mode1;
5676 int reversed_nonequality = 0;
5679 /* Ensure this is the right kind of insn. */
5680 if (! condjump_p (insn) || simplejump_p (insn))
5683 /* See if this jump condition is known true or false. */
5685 cond_known_true = (XEXP (SET_SRC (PATTERN (insn)), 2) == pc_rtx);
5687 cond_known_true = (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx);
5689 /* Get the type of comparison being done and the operands being compared.
5690 If we had to reverse a non-equality condition, record that fact so we
5691 know that it isn't valid for floating-point. */
5692 code = GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 0));
5693 op0 = fold_rtx (XEXP (XEXP (SET_SRC (PATTERN (insn)), 0), 0), insn);
5694 op1 = fold_rtx (XEXP (XEXP (SET_SRC (PATTERN (insn)), 0), 1), insn);
5696 code = find_comparison_args (code, &op0, &op1, &mode0, &mode1);
5697 if (! cond_known_true)
5699 reversed_nonequality = (code != EQ && code != NE);
5700 code = reverse_condition (code);
5703 /* The mode is the mode of the non-constant. */
5705 if (mode1 != VOIDmode)
5708 record_jump_cond (code, mode, op0, op1, reversed_nonequality);
5711 /* We know that comparison CODE applied to OP0 and OP1 in MODE is true.
5712 REVERSED_NONEQUALITY is nonzero if CODE had to be swapped.
5713 Make any useful entries we can with that information. Called from
5714 above function and called recursively. */
5717 record_jump_cond (code, mode, op0, op1, reversed_nonequality)
5719 enum machine_mode mode;
5721 int reversed_nonequality;
5723 unsigned op0_hash, op1_hash;
5724 int op0_in_memory, op0_in_struct, op1_in_memory, op1_in_struct;
5725 struct table_elt *op0_elt, *op1_elt;
5727 /* If OP0 and OP1 are known equal, and either is a paradoxical SUBREG,
5728 we know that they are also equal in the smaller mode (this is also
5729 true for all smaller modes whether or not there is a SUBREG, but
5730 is not worth testing for with no SUBREG. */
5732 /* Note that GET_MODE (op0) may not equal MODE. */
5733 if (code == EQ && GET_CODE (op0) == SUBREG
5734 && (GET_MODE_SIZE (GET_MODE (op0))
5735 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0)))))
5737 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op0));
5738 rtx tem = gen_lowpart_if_possible (inner_mode, op1);
5740 record_jump_cond (code, mode, SUBREG_REG (op0),
5741 tem ? tem : gen_rtx (SUBREG, inner_mode, op1, 0),
5742 reversed_nonequality);
5745 if (code == EQ && GET_CODE (op1) == SUBREG
5746 && (GET_MODE_SIZE (GET_MODE (op1))
5747 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op1)))))
5749 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op1));
5750 rtx tem = gen_lowpart_if_possible (inner_mode, op0);
5752 record_jump_cond (code, mode, SUBREG_REG (op1),
5753 tem ? tem : gen_rtx (SUBREG, inner_mode, op0, 0),
5754 reversed_nonequality);
5757 /* Similarly, if this is an NE comparison, and either is a SUBREG
5758 making a smaller mode, we know the whole thing is also NE. */
5760 /* Note that GET_MODE (op0) may not equal MODE;
5761 if we test MODE instead, we can get an infinite recursion
5762 alternating between two modes each wider than MODE. */
5764 if (code == NE && GET_CODE (op0) == SUBREG
5765 && subreg_lowpart_p (op0)
5766 && (GET_MODE_SIZE (GET_MODE (op0))
5767 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0)))))
5769 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op0));
5770 rtx tem = gen_lowpart_if_possible (inner_mode, op1);
5772 record_jump_cond (code, mode, SUBREG_REG (op0),
5773 tem ? tem : gen_rtx (SUBREG, inner_mode, op1, 0),
5774 reversed_nonequality);
5777 if (code == NE && GET_CODE (op1) == SUBREG
5778 && subreg_lowpart_p (op1)
5779 && (GET_MODE_SIZE (GET_MODE (op1))
5780 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op1)))))
5782 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op1));
5783 rtx tem = gen_lowpart_if_possible (inner_mode, op0);
5785 record_jump_cond (code, mode, SUBREG_REG (op1),
5786 tem ? tem : gen_rtx (SUBREG, inner_mode, op0, 0),
5787 reversed_nonequality);
5790 /* Hash both operands. */
5793 hash_arg_in_memory = 0;
5794 hash_arg_in_struct = 0;
5795 op0_hash = HASH (op0, mode);
5796 op0_in_memory = hash_arg_in_memory;
5797 op0_in_struct = hash_arg_in_struct;
5803 hash_arg_in_memory = 0;
5804 hash_arg_in_struct = 0;
5805 op1_hash = HASH (op1, mode);
5806 op1_in_memory = hash_arg_in_memory;
5807 op1_in_struct = hash_arg_in_struct;
5812 /* Look up both operands. */
5813 op0_elt = lookup (op0, op0_hash, mode);
5814 op1_elt = lookup (op1, op1_hash, mode);
5816 /* If both operands are already equivalent or if they are not in the
5817 table but are identical, do nothing. */
5818 if ((op0_elt != 0 && op1_elt != 0
5819 && op0_elt->first_same_value == op1_elt->first_same_value)
5820 || op0 == op1 || rtx_equal_p (op0, op1))
5823 /* If we aren't setting two things equal all we can do is save this
5824 comparison. Similarly if this is floating-point. In the latter
5825 case, OP1 might be zero and both -0.0 and 0.0 are equal to it.
5826 If we record the equality, we might inadvertently delete code
5827 whose intent was to change -0 to +0. */
5829 if (code != EQ || FLOAT_MODE_P (GET_MODE (op0)))
5831 /* If we reversed a floating-point comparison, if OP0 is not a
5832 register, or if OP1 is neither a register or constant, we can't
5835 if (GET_CODE (op1) != REG)
5836 op1 = equiv_constant (op1);
5838 if ((reversed_nonequality && FLOAT_MODE_P (mode))
5839 || GET_CODE (op0) != REG || op1 == 0)
5842 /* Put OP0 in the hash table if it isn't already. This gives it a
5843 new quantity number. */
5846 if (insert_regs (op0, NULL_PTR, 0))
5848 rehash_using_reg (op0);
5849 op0_hash = HASH (op0, mode);
5851 /* If OP0 is contained in OP1, this changes its hash code
5852 as well. Faster to rehash than to check, except
5853 for the simple case of a constant. */
5854 if (! CONSTANT_P (op1))
5855 op1_hash = HASH (op1,mode);
5858 op0_elt = insert (op0, NULL_PTR, op0_hash, mode);
5859 op0_elt->in_memory = op0_in_memory;
5860 op0_elt->in_struct = op0_in_struct;
5863 qty_comparison_code[reg_qty[REGNO (op0)]] = code;
5864 if (GET_CODE (op1) == REG)
5866 /* Look it up again--in case op0 and op1 are the same. */
5867 op1_elt = lookup (op1, op1_hash, mode);
5869 /* Put OP1 in the hash table so it gets a new quantity number. */
5872 if (insert_regs (op1, NULL_PTR, 0))
5874 rehash_using_reg (op1);
5875 op1_hash = HASH (op1, mode);
5878 op1_elt = insert (op1, NULL_PTR, op1_hash, mode);
5879 op1_elt->in_memory = op1_in_memory;
5880 op1_elt->in_struct = op1_in_struct;
5883 qty_comparison_qty[reg_qty[REGNO (op0)]] = reg_qty[REGNO (op1)];
5884 qty_comparison_const[reg_qty[REGNO (op0)]] = 0;
5888 qty_comparison_qty[reg_qty[REGNO (op0)]] = -1;
5889 qty_comparison_const[reg_qty[REGNO (op0)]] = op1;
5895 /* If either side is still missing an equivalence, make it now,
5896 then merge the equivalences. */
5900 if (insert_regs (op0, NULL_PTR, 0))
5902 rehash_using_reg (op0);
5903 op0_hash = HASH (op0, mode);
5906 op0_elt = insert (op0, NULL_PTR, op0_hash, mode);
5907 op0_elt->in_memory = op0_in_memory;
5908 op0_elt->in_struct = op0_in_struct;
5913 if (insert_regs (op1, NULL_PTR, 0))
5915 rehash_using_reg (op1);
5916 op1_hash = HASH (op1, mode);
5919 op1_elt = insert (op1, NULL_PTR, op1_hash, mode);
5920 op1_elt->in_memory = op1_in_memory;
5921 op1_elt->in_struct = op1_in_struct;
5924 merge_equiv_classes (op0_elt, op1_elt);
5925 last_jump_equiv_class = op0_elt;
5928 /* CSE processing for one instruction.
5929 First simplify sources and addresses of all assignments
5930 in the instruction, using previously-computed equivalents values.
5931 Then install the new sources and destinations in the table
5932 of available values.
5934 If IN_LIBCALL_BLOCK is nonzero, don't record any equivalence made in
5937 /* Data on one SET contained in the instruction. */
5941 /* The SET rtx itself. */
5943 /* The SET_SRC of the rtx (the original value, if it is changing). */
5945 /* The hash-table element for the SET_SRC of the SET. */
5946 struct table_elt *src_elt;
5947 /* Hash value for the SET_SRC. */
5949 /* Hash value for the SET_DEST. */
5951 /* The SET_DEST, with SUBREG, etc., stripped. */
5953 /* Place where the pointer to the INNER_DEST was found. */
5954 rtx *inner_dest_loc;
5955 /* Nonzero if the SET_SRC is in memory. */
5957 /* Nonzero if the SET_SRC is in a structure. */
5959 /* Nonzero if the SET_SRC contains something
5960 whose value cannot be predicted and understood. */
5962 /* Original machine mode, in case it becomes a CONST_INT. */
5963 enum machine_mode mode;
5964 /* A constant equivalent for SET_SRC, if any. */
5966 /* Hash value of constant equivalent for SET_SRC. */
5967 unsigned src_const_hash;
5968 /* Table entry for constant equivalent for SET_SRC, if any. */
5969 struct table_elt *src_const_elt;
5973 cse_insn (insn, in_libcall_block)
5975 int in_libcall_block;
5977 register rtx x = PATTERN (insn);
5980 register int n_sets = 0;
5982 /* Records what this insn does to set CC0. */
5983 rtx this_insn_cc0 = 0;
5984 enum machine_mode this_insn_cc0_mode;
5985 struct write_data writes_memory;
5986 static struct write_data init = {0, 0, 0, 0};
5989 struct table_elt *src_eqv_elt = 0;
5990 int src_eqv_volatile;
5991 int src_eqv_in_memory;
5992 int src_eqv_in_struct;
5993 unsigned src_eqv_hash;
5998 writes_memory = init;
6000 /* Find all the SETs and CLOBBERs in this instruction.
6001 Record all the SETs in the array `set' and count them.
6002 Also determine whether there is a CLOBBER that invalidates
6003 all memory references, or all references at varying addresses. */
6005 if (GET_CODE (insn) == CALL_INSN)
6007 for (tem = CALL_INSN_FUNCTION_USAGE (insn); tem; tem = XEXP (tem, 1))
6008 if (GET_CODE (XEXP (tem, 0)) == CLOBBER)
6009 invalidate (SET_DEST (XEXP (tem, 0)), VOIDmode);
6012 if (GET_CODE (x) == SET)
6014 sets = (struct set *) alloca (sizeof (struct set));
6017 /* Ignore SETs that are unconditional jumps.
6018 They never need cse processing, so this does not hurt.
6019 The reason is not efficiency but rather
6020 so that we can test at the end for instructions
6021 that have been simplified to unconditional jumps
6022 and not be misled by unchanged instructions
6023 that were unconditional jumps to begin with. */
6024 if (SET_DEST (x) == pc_rtx
6025 && GET_CODE (SET_SRC (x)) == LABEL_REF)
6028 /* Don't count call-insns, (set (reg 0) (call ...)), as a set.
6029 The hard function value register is used only once, to copy to
6030 someplace else, so it isn't worth cse'ing (and on 80386 is unsafe)!
6031 Ensure we invalidate the destination register. On the 80386 no
6032 other code would invalidate it since it is a fixed_reg.
6033 We need not check the return of apply_change_group; see canon_reg. */
6035 else if (GET_CODE (SET_SRC (x)) == CALL)
6037 canon_reg (SET_SRC (x), insn);
6038 apply_change_group ();
6039 fold_rtx (SET_SRC (x), insn);
6040 invalidate (SET_DEST (x), VOIDmode);
6045 else if (GET_CODE (x) == PARALLEL)
6047 register int lim = XVECLEN (x, 0);
6049 sets = (struct set *) alloca (lim * sizeof (struct set));
6051 /* Find all regs explicitly clobbered in this insn,
6052 and ensure they are not replaced with any other regs
6053 elsewhere in this insn.
6054 When a reg that is clobbered is also used for input,
6055 we should presume that that is for a reason,
6056 and we should not substitute some other register
6057 which is not supposed to be clobbered.
6058 Therefore, this loop cannot be merged into the one below
6059 because a CALL may precede a CLOBBER and refer to the
6060 value clobbered. We must not let a canonicalization do
6061 anything in that case. */
6062 for (i = 0; i < lim; i++)
6064 register rtx y = XVECEXP (x, 0, i);
6065 if (GET_CODE (y) == CLOBBER)
6067 rtx clobbered = XEXP (y, 0);
6069 if (GET_CODE (clobbered) == REG
6070 || GET_CODE (clobbered) == SUBREG)
6071 invalidate (clobbered, VOIDmode);
6072 else if (GET_CODE (clobbered) == STRICT_LOW_PART
6073 || GET_CODE (clobbered) == ZERO_EXTRACT)
6074 invalidate (XEXP (clobbered, 0), GET_MODE (clobbered));
6078 for (i = 0; i < lim; i++)
6080 register rtx y = XVECEXP (x, 0, i);
6081 if (GET_CODE (y) == SET)
6083 /* As above, we ignore unconditional jumps and call-insns and
6084 ignore the result of apply_change_group. */
6085 if (GET_CODE (SET_SRC (y)) == CALL)
6087 canon_reg (SET_SRC (y), insn);
6088 apply_change_group ();
6089 fold_rtx (SET_SRC (y), insn);
6090 invalidate (SET_DEST (y), VOIDmode);
6092 else if (SET_DEST (y) == pc_rtx
6093 && GET_CODE (SET_SRC (y)) == LABEL_REF)
6096 sets[n_sets++].rtl = y;
6098 else if (GET_CODE (y) == CLOBBER)
6100 /* If we clobber memory, take note of that,
6101 and canon the address.
6102 This does nothing when a register is clobbered
6103 because we have already invalidated the reg. */
6104 if (GET_CODE (XEXP (y, 0)) == MEM)
6106 canon_reg (XEXP (y, 0), NULL_RTX);
6107 note_mem_written (XEXP (y, 0), &writes_memory);
6110 else if (GET_CODE (y) == USE
6111 && ! (GET_CODE (XEXP (y, 0)) == REG
6112 && REGNO (XEXP (y, 0)) < FIRST_PSEUDO_REGISTER))
6113 canon_reg (y, NULL_RTX);
6114 else if (GET_CODE (y) == CALL)
6116 /* The result of apply_change_group can be ignored; see
6118 canon_reg (y, insn);
6119 apply_change_group ();
6124 else if (GET_CODE (x) == CLOBBER)
6126 if (GET_CODE (XEXP (x, 0)) == MEM)
6128 canon_reg (XEXP (x, 0), NULL_RTX);
6129 note_mem_written (XEXP (x, 0), &writes_memory);
6133 /* Canonicalize a USE of a pseudo register or memory location. */
6134 else if (GET_CODE (x) == USE
6135 && ! (GET_CODE (XEXP (x, 0)) == REG
6136 && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER))
6137 canon_reg (XEXP (x, 0), NULL_RTX);
6138 else if (GET_CODE (x) == CALL)
6140 /* The result of apply_change_group can be ignored; see canon_reg. */
6141 canon_reg (x, insn);
6142 apply_change_group ();
6146 /* Store the equivalent value in SRC_EQV, if different, or if the DEST
6147 is a STRICT_LOW_PART. The latter condition is necessary because SRC_EQV
6148 is handled specially for this case, and if it isn't set, then there will
6149 be no equivalence for the destinatation. */
6150 if (n_sets == 1 && REG_NOTES (insn) != 0
6151 && (tem = find_reg_note (insn, REG_EQUAL, NULL_RTX)) != 0
6152 && (! rtx_equal_p (XEXP (tem, 0), SET_SRC (sets[0].rtl))
6153 || GET_CODE (SET_DEST (sets[0].rtl)) == STRICT_LOW_PART))
6154 src_eqv = canon_reg (XEXP (tem, 0), NULL_RTX);
6156 /* Canonicalize sources and addresses of destinations.
6157 We do this in a separate pass to avoid problems when a MATCH_DUP is
6158 present in the insn pattern. In that case, we want to ensure that
6159 we don't break the duplicate nature of the pattern. So we will replace
6160 both operands at the same time. Otherwise, we would fail to find an
6161 equivalent substitution in the loop calling validate_change below.
6163 We used to suppress canonicalization of DEST if it appears in SRC,
6164 but we don't do this any more. */
6166 for (i = 0; i < n_sets; i++)
6168 rtx dest = SET_DEST (sets[i].rtl);
6169 rtx src = SET_SRC (sets[i].rtl);
6170 rtx new = canon_reg (src, insn);
6172 if ((GET_CODE (new) == REG && GET_CODE (src) == REG
6173 && ((REGNO (new) < FIRST_PSEUDO_REGISTER)
6174 != (REGNO (src) < FIRST_PSEUDO_REGISTER)))
6175 || insn_n_dups[recog_memoized (insn)] > 0)
6176 validate_change (insn, &SET_SRC (sets[i].rtl), new, 1);
6178 SET_SRC (sets[i].rtl) = new;
6180 if (GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SIGN_EXTRACT)
6182 validate_change (insn, &XEXP (dest, 1),
6183 canon_reg (XEXP (dest, 1), insn), 1);
6184 validate_change (insn, &XEXP (dest, 2),
6185 canon_reg (XEXP (dest, 2), insn), 1);
6188 while (GET_CODE (dest) == SUBREG || GET_CODE (dest) == STRICT_LOW_PART
6189 || GET_CODE (dest) == ZERO_EXTRACT
6190 || GET_CODE (dest) == SIGN_EXTRACT)
6191 dest = XEXP (dest, 0);
6193 if (GET_CODE (dest) == MEM)
6194 canon_reg (dest, insn);
6197 /* Now that we have done all the replacements, we can apply the change
6198 group and see if they all work. Note that this will cause some
6199 canonicalizations that would have worked individually not to be applied
6200 because some other canonicalization didn't work, but this should not
6203 The result of apply_change_group can be ignored; see canon_reg. */
6205 apply_change_group ();
6207 /* Set sets[i].src_elt to the class each source belongs to.
6208 Detect assignments from or to volatile things
6209 and set set[i] to zero so they will be ignored
6210 in the rest of this function.
6212 Nothing in this loop changes the hash table or the register chains. */
6214 for (i = 0; i < n_sets; i++)
6216 register rtx src, dest;
6217 register rtx src_folded;
6218 register struct table_elt *elt = 0, *p;
6219 enum machine_mode mode;
6222 rtx src_related = 0;
6223 struct table_elt *src_const_elt = 0;
6224 int src_cost = 10000, src_eqv_cost = 10000, src_folded_cost = 10000;
6225 int src_related_cost = 10000, src_elt_cost = 10000;
6226 /* Set non-zero if we need to call force_const_mem on with the
6227 contents of src_folded before using it. */
6228 int src_folded_force_flag = 0;
6230 dest = SET_DEST (sets[i].rtl);
6231 src = SET_SRC (sets[i].rtl);
6233 /* If SRC is a constant that has no machine mode,
6234 hash it with the destination's machine mode.
6235 This way we can keep different modes separate. */
6237 mode = GET_MODE (src) == VOIDmode ? GET_MODE (dest) : GET_MODE (src);
6238 sets[i].mode = mode;
6242 enum machine_mode eqvmode = mode;
6243 if (GET_CODE (dest) == STRICT_LOW_PART)
6244 eqvmode = GET_MODE (SUBREG_REG (XEXP (dest, 0)));
6246 hash_arg_in_memory = 0;
6247 hash_arg_in_struct = 0;
6248 src_eqv = fold_rtx (src_eqv, insn);
6249 src_eqv_hash = HASH (src_eqv, eqvmode);
6251 /* Find the equivalence class for the equivalent expression. */
6254 src_eqv_elt = lookup (src_eqv, src_eqv_hash, eqvmode);
6256 src_eqv_volatile = do_not_record;
6257 src_eqv_in_memory = hash_arg_in_memory;
6258 src_eqv_in_struct = hash_arg_in_struct;
6261 /* If this is a STRICT_LOW_PART assignment, src_eqv corresponds to the
6262 value of the INNER register, not the destination. So it is not
6263 a legal substitution for the source. But save it for later. */
6264 if (GET_CODE (dest) == STRICT_LOW_PART)
6267 src_eqv_here = src_eqv;
6269 /* Simplify and foldable subexpressions in SRC. Then get the fully-
6270 simplified result, which may not necessarily be valid. */
6271 src_folded = fold_rtx (src, insn);
6273 /* If storing a constant in a bitfield, pre-truncate the constant
6274 so we will be able to record it later. */
6275 if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT
6276 || GET_CODE (SET_DEST (sets[i].rtl)) == SIGN_EXTRACT)
6278 rtx width = XEXP (SET_DEST (sets[i].rtl), 1);
6280 if (GET_CODE (src) == CONST_INT
6281 && GET_CODE (width) == CONST_INT
6282 && INTVAL (width) < HOST_BITS_PER_WIDE_INT
6283 && (INTVAL (src) & ((HOST_WIDE_INT) (-1) << INTVAL (width))))
6285 = GEN_INT (INTVAL (src) & (((HOST_WIDE_INT) 1
6286 << INTVAL (width)) - 1));
6289 /* Compute SRC's hash code, and also notice if it
6290 should not be recorded at all. In that case,
6291 prevent any further processing of this assignment. */
6293 hash_arg_in_memory = 0;
6294 hash_arg_in_struct = 0;
6297 sets[i].src_hash = HASH (src, mode);
6298 sets[i].src_volatile = do_not_record;
6299 sets[i].src_in_memory = hash_arg_in_memory;
6300 sets[i].src_in_struct = hash_arg_in_struct;
6303 /* It is no longer clear why we used to do this, but it doesn't
6304 appear to still be needed. So let's try without it since this
6305 code hurts cse'ing widened ops. */
6306 /* If source is a perverse subreg (such as QI treated as an SI),
6307 treat it as volatile. It may do the work of an SI in one context
6308 where the extra bits are not being used, but cannot replace an SI
6310 if (GET_CODE (src) == SUBREG
6311 && (GET_MODE_SIZE (GET_MODE (src))
6312 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (src)))))
6313 sets[i].src_volatile = 1;
6316 /* Locate all possible equivalent forms for SRC. Try to replace
6317 SRC in the insn with each cheaper equivalent.
6319 We have the following types of equivalents: SRC itself, a folded
6320 version, a value given in a REG_EQUAL note, or a value related
6323 Each of these equivalents may be part of an additional class
6324 of equivalents (if more than one is in the table, they must be in
6325 the same class; we check for this).
6327 If the source is volatile, we don't do any table lookups.
6329 We note any constant equivalent for possible later use in a
6332 if (!sets[i].src_volatile)
6333 elt = lookup (src, sets[i].src_hash, mode);
6335 sets[i].src_elt = elt;
6337 if (elt && src_eqv_here && src_eqv_elt)
6339 if (elt->first_same_value != src_eqv_elt->first_same_value)
6341 /* The REG_EQUAL is indicating that two formerly distinct
6342 classes are now equivalent. So merge them. */
6343 merge_equiv_classes (elt, src_eqv_elt);
6344 src_eqv_hash = HASH (src_eqv, elt->mode);
6345 src_eqv_elt = lookup (src_eqv, src_eqv_hash, elt->mode);
6351 else if (src_eqv_elt)
6354 /* Try to find a constant somewhere and record it in `src_const'.
6355 Record its table element, if any, in `src_const_elt'. Look in
6356 any known equivalences first. (If the constant is not in the
6357 table, also set `sets[i].src_const_hash'). */
6359 for (p = elt->first_same_value; p; p = p->next_same_value)
6363 src_const_elt = elt;
6368 && (CONSTANT_P (src_folded)
6369 /* Consider (minus (label_ref L1) (label_ref L2)) as
6370 "constant" here so we will record it. This allows us
6371 to fold switch statements when an ADDR_DIFF_VEC is used. */
6372 || (GET_CODE (src_folded) == MINUS
6373 && GET_CODE (XEXP (src_folded, 0)) == LABEL_REF
6374 && GET_CODE (XEXP (src_folded, 1)) == LABEL_REF)))
6375 src_const = src_folded, src_const_elt = elt;
6376 else if (src_const == 0 && src_eqv_here && CONSTANT_P (src_eqv_here))
6377 src_const = src_eqv_here, src_const_elt = src_eqv_elt;
6379 /* If we don't know if the constant is in the table, get its
6380 hash code and look it up. */
6381 if (src_const && src_const_elt == 0)
6383 sets[i].src_const_hash = HASH (src_const, mode);
6384 src_const_elt = lookup (src_const, sets[i].src_const_hash, mode);
6387 sets[i].src_const = src_const;
6388 sets[i].src_const_elt = src_const_elt;
6390 /* If the constant and our source are both in the table, mark them as
6391 equivalent. Otherwise, if a constant is in the table but the source
6392 isn't, set ELT to it. */
6393 if (src_const_elt && elt
6394 && src_const_elt->first_same_value != elt->first_same_value)
6395 merge_equiv_classes (elt, src_const_elt);
6396 else if (src_const_elt && elt == 0)
6397 elt = src_const_elt;
6399 /* See if there is a register linearly related to a constant
6400 equivalent of SRC. */
6402 && (GET_CODE (src_const) == CONST
6403 || (src_const_elt && src_const_elt->related_value != 0)))
6405 src_related = use_related_value (src_const, src_const_elt);
6408 struct table_elt *src_related_elt
6409 = lookup (src_related, HASH (src_related, mode), mode);
6410 if (src_related_elt && elt)
6412 if (elt->first_same_value
6413 != src_related_elt->first_same_value)
6414 /* This can occur when we previously saw a CONST
6415 involving a SYMBOL_REF and then see the SYMBOL_REF
6416 twice. Merge the involved classes. */
6417 merge_equiv_classes (elt, src_related_elt);
6420 src_related_elt = 0;
6422 else if (src_related_elt && elt == 0)
6423 elt = src_related_elt;
6427 /* See if we have a CONST_INT that is already in a register in a
6430 if (src_const && src_related == 0 && GET_CODE (src_const) == CONST_INT
6431 && GET_MODE_CLASS (mode) == MODE_INT
6432 && GET_MODE_BITSIZE (mode) < BITS_PER_WORD)
6434 enum machine_mode wider_mode;
6436 for (wider_mode = GET_MODE_WIDER_MODE (mode);
6437 GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD
6438 && src_related == 0;
6439 wider_mode = GET_MODE_WIDER_MODE (wider_mode))
6441 struct table_elt *const_elt
6442 = lookup (src_const, HASH (src_const, wider_mode), wider_mode);
6447 for (const_elt = const_elt->first_same_value;
6448 const_elt; const_elt = const_elt->next_same_value)
6449 if (GET_CODE (const_elt->exp) == REG)
6451 src_related = gen_lowpart_if_possible (mode,
6458 /* Another possibility is that we have an AND with a constant in
6459 a mode narrower than a word. If so, it might have been generated
6460 as part of an "if" which would narrow the AND. If we already
6461 have done the AND in a wider mode, we can use a SUBREG of that
6464 if (flag_expensive_optimizations && ! src_related
6465 && GET_CODE (src) == AND && GET_CODE (XEXP (src, 1)) == CONST_INT
6466 && GET_MODE_SIZE (mode) < UNITS_PER_WORD)
6468 enum machine_mode tmode;
6469 rtx new_and = gen_rtx (AND, VOIDmode, NULL_RTX, XEXP (src, 1));
6471 for (tmode = GET_MODE_WIDER_MODE (mode);
6472 GET_MODE_SIZE (tmode) <= UNITS_PER_WORD;
6473 tmode = GET_MODE_WIDER_MODE (tmode))
6475 rtx inner = gen_lowpart_if_possible (tmode, XEXP (src, 0));
6476 struct table_elt *larger_elt;
6480 PUT_MODE (new_and, tmode);
6481 XEXP (new_and, 0) = inner;
6482 larger_elt = lookup (new_and, HASH (new_and, tmode), tmode);
6483 if (larger_elt == 0)
6486 for (larger_elt = larger_elt->first_same_value;
6487 larger_elt; larger_elt = larger_elt->next_same_value)
6488 if (GET_CODE (larger_elt->exp) == REG)
6491 = gen_lowpart_if_possible (mode, larger_elt->exp);
6501 #ifdef LOAD_EXTEND_OP
6502 /* See if a MEM has already been loaded with a widening operation;
6503 if it has, we can use a subreg of that. Many CISC machines
6504 also have such operations, but this is only likely to be
6505 beneficial these machines. */
6507 if (flag_expensive_optimizations && src_related == 0
6508 && (GET_MODE_SIZE (mode) < UNITS_PER_WORD)
6509 && GET_MODE_CLASS (mode) == MODE_INT
6510 && GET_CODE (src) == MEM && ! do_not_record
6511 && LOAD_EXTEND_OP (mode) != NIL)
6513 enum machine_mode tmode;
6515 /* Set what we are trying to extend and the operation it might
6516 have been extended with. */
6517 PUT_CODE (memory_extend_rtx, LOAD_EXTEND_OP (mode));
6518 XEXP (memory_extend_rtx, 0) = src;
6520 for (tmode = GET_MODE_WIDER_MODE (mode);
6521 GET_MODE_SIZE (tmode) <= UNITS_PER_WORD;
6522 tmode = GET_MODE_WIDER_MODE (tmode))
6524 struct table_elt *larger_elt;
6526 PUT_MODE (memory_extend_rtx, tmode);
6527 larger_elt = lookup (memory_extend_rtx,
6528 HASH (memory_extend_rtx, tmode), tmode);
6529 if (larger_elt == 0)
6532 for (larger_elt = larger_elt->first_same_value;
6533 larger_elt; larger_elt = larger_elt->next_same_value)
6534 if (GET_CODE (larger_elt->exp) == REG)
6536 src_related = gen_lowpart_if_possible (mode,
6545 #endif /* LOAD_EXTEND_OP */
6547 if (src == src_folded)
6550 /* At this point, ELT, if non-zero, points to a class of expressions
6551 equivalent to the source of this SET and SRC, SRC_EQV, SRC_FOLDED,
6552 and SRC_RELATED, if non-zero, each contain additional equivalent
6553 expressions. Prune these latter expressions by deleting expressions
6554 already in the equivalence class.
6556 Check for an equivalent identical to the destination. If found,
6557 this is the preferred equivalent since it will likely lead to
6558 elimination of the insn. Indicate this by placing it in
6561 if (elt) elt = elt->first_same_value;
6562 for (p = elt; p; p = p->next_same_value)
6564 enum rtx_code code = GET_CODE (p->exp);
6566 /* If the expression is not valid, ignore it. Then we do not
6567 have to check for validity below. In most cases, we can use
6568 `rtx_equal_p', since canonicalization has already been done. */
6569 if (code != REG && ! exp_equiv_p (p->exp, p->exp, 1, 0))
6572 if (src && GET_CODE (src) == code && rtx_equal_p (src, p->exp))
6574 else if (src_folded && GET_CODE (src_folded) == code
6575 && rtx_equal_p (src_folded, p->exp))
6577 else if (src_eqv_here && GET_CODE (src_eqv_here) == code
6578 && rtx_equal_p (src_eqv_here, p->exp))
6580 else if (src_related && GET_CODE (src_related) == code
6581 && rtx_equal_p (src_related, p->exp))
6584 /* This is the same as the destination of the insns, we want
6585 to prefer it. Copy it to src_related. The code below will
6586 then give it a negative cost. */
6587 if (GET_CODE (dest) == code && rtx_equal_p (p->exp, dest))
6592 /* Find the cheapest valid equivalent, trying all the available
6593 possibilities. Prefer items not in the hash table to ones
6594 that are when they are equal cost. Note that we can never
6595 worsen an insn as the current contents will also succeed.
6596 If we find an equivalent identical to the destination, use it as best,
6597 since this insn will probably be eliminated in that case. */
6600 if (rtx_equal_p (src, dest))
6603 src_cost = COST (src);
6608 if (rtx_equal_p (src_eqv_here, dest))
6611 src_eqv_cost = COST (src_eqv_here);
6616 if (rtx_equal_p (src_folded, dest))
6617 src_folded_cost = -1;
6619 src_folded_cost = COST (src_folded);
6624 if (rtx_equal_p (src_related, dest))
6625 src_related_cost = -1;
6627 src_related_cost = COST (src_related);
6630 /* If this was an indirect jump insn, a known label will really be
6631 cheaper even though it looks more expensive. */
6632 if (dest == pc_rtx && src_const && GET_CODE (src_const) == LABEL_REF)
6633 src_folded = src_const, src_folded_cost = -1;
6635 /* Terminate loop when replacement made. This must terminate since
6636 the current contents will be tested and will always be valid. */
6641 /* Skip invalid entries. */
6642 while (elt && GET_CODE (elt->exp) != REG
6643 && ! exp_equiv_p (elt->exp, elt->exp, 1, 0))
6644 elt = elt->next_same_value;
6646 if (elt) src_elt_cost = elt->cost;
6648 /* Find cheapest and skip it for the next time. For items
6649 of equal cost, use this order:
6650 src_folded, src, src_eqv, src_related and hash table entry. */
6651 if (src_folded_cost <= src_cost
6652 && src_folded_cost <= src_eqv_cost
6653 && src_folded_cost <= src_related_cost
6654 && src_folded_cost <= src_elt_cost)
6656 trial = src_folded, src_folded_cost = 10000;
6657 if (src_folded_force_flag)
6658 trial = force_const_mem (mode, trial);
6660 else if (src_cost <= src_eqv_cost
6661 && src_cost <= src_related_cost
6662 && src_cost <= src_elt_cost)
6663 trial = src, src_cost = 10000;
6664 else if (src_eqv_cost <= src_related_cost
6665 && src_eqv_cost <= src_elt_cost)
6666 trial = copy_rtx (src_eqv_here), src_eqv_cost = 10000;
6667 else if (src_related_cost <= src_elt_cost)
6668 trial = copy_rtx (src_related), src_related_cost = 10000;
6671 trial = copy_rtx (elt->exp);
6672 elt = elt->next_same_value;
6673 src_elt_cost = 10000;
6676 /* We don't normally have an insn matching (set (pc) (pc)), so
6677 check for this separately here. We will delete such an
6680 Tablejump insns contain a USE of the table, so simply replacing
6681 the operand with the constant won't match. This is simply an
6682 unconditional branch, however, and is therefore valid. Just
6683 insert the substitution here and we will delete and re-emit
6686 if (n_sets == 1 && dest == pc_rtx
6688 || (GET_CODE (trial) == LABEL_REF
6689 && ! condjump_p (insn))))
6691 /* If TRIAL is a label in front of a jump table, we are
6692 really falling through the switch (this is how casesi
6693 insns work), so we must branch around the table. */
6694 if (GET_CODE (trial) == CODE_LABEL
6695 && NEXT_INSN (trial) != 0
6696 && GET_CODE (NEXT_INSN (trial)) == JUMP_INSN
6697 && (GET_CODE (PATTERN (NEXT_INSN (trial))) == ADDR_DIFF_VEC
6698 || GET_CODE (PATTERN (NEXT_INSN (trial))) == ADDR_VEC))
6700 trial = gen_rtx (LABEL_REF, Pmode, get_label_after (trial));
6702 SET_SRC (sets[i].rtl) = trial;
6703 cse_jumps_altered = 1;
6707 /* Look for a substitution that makes a valid insn. */
6708 else if (validate_change (insn, &SET_SRC (sets[i].rtl), trial, 0))
6710 /* The result of apply_change_group can be ignored; see
6713 validate_change (insn, &SET_SRC (sets[i].rtl),
6714 canon_reg (SET_SRC (sets[i].rtl), insn),
6716 apply_change_group ();
6720 /* If we previously found constant pool entries for
6721 constants and this is a constant, try making a
6722 pool entry. Put it in src_folded unless we already have done
6723 this since that is where it likely came from. */
6725 else if (constant_pool_entries_cost
6726 && CONSTANT_P (trial)
6727 && (src_folded == 0 || GET_CODE (src_folded) != MEM)
6728 && GET_MODE_CLASS (mode) != MODE_CC)
6730 src_folded_force_flag = 1;
6732 src_folded_cost = constant_pool_entries_cost;
6736 src = SET_SRC (sets[i].rtl);
6738 /* In general, it is good to have a SET with SET_SRC == SET_DEST.
6739 However, there is an important exception: If both are registers
6740 that are not the head of their equivalence class, replace SET_SRC
6741 with the head of the class. If we do not do this, we will have
6742 both registers live over a portion of the basic block. This way,
6743 their lifetimes will likely abut instead of overlapping. */
6744 if (GET_CODE (dest) == REG
6745 && REGNO_QTY_VALID_P (REGNO (dest))
6746 && qty_mode[reg_qty[REGNO (dest)]] == GET_MODE (dest)
6747 && qty_first_reg[reg_qty[REGNO (dest)]] != REGNO (dest)
6748 && GET_CODE (src) == REG && REGNO (src) == REGNO (dest)
6749 /* Don't do this if the original insn had a hard reg as
6751 && (GET_CODE (sets[i].src) != REG
6752 || REGNO (sets[i].src) >= FIRST_PSEUDO_REGISTER))
6753 /* We can't call canon_reg here because it won't do anything if
6754 SRC is a hard register. */
6756 int first = qty_first_reg[reg_qty[REGNO (src)]];
6758 src = SET_SRC (sets[i].rtl)
6759 = first >= FIRST_PSEUDO_REGISTER ? regno_reg_rtx[first]
6760 : gen_rtx (REG, GET_MODE (src), first);
6762 /* If we had a constant that is cheaper than what we are now
6763 setting SRC to, use that constant. We ignored it when we
6764 thought we could make this into a no-op. */
6765 if (src_const && COST (src_const) < COST (src)
6766 && validate_change (insn, &SET_SRC (sets[i].rtl), src_const, 0))
6770 /* If we made a change, recompute SRC values. */
6771 if (src != sets[i].src)
6774 hash_arg_in_memory = 0;
6775 hash_arg_in_struct = 0;
6777 sets[i].src_hash = HASH (src, mode);
6778 sets[i].src_volatile = do_not_record;
6779 sets[i].src_in_memory = hash_arg_in_memory;
6780 sets[i].src_in_struct = hash_arg_in_struct;
6781 sets[i].src_elt = lookup (src, sets[i].src_hash, mode);
6784 /* If this is a single SET, we are setting a register, and we have an
6785 equivalent constant, we want to add a REG_NOTE. We don't want
6786 to write a REG_EQUAL note for a constant pseudo since verifying that
6787 that pseudo hasn't been eliminated is a pain. Such a note also
6788 won't help anything. */
6789 if (n_sets == 1 && src_const && GET_CODE (dest) == REG
6790 && GET_CODE (src_const) != REG)
6792 tem = find_reg_note (insn, REG_EQUAL, NULL_RTX);
6794 /* Record the actual constant value in a REG_EQUAL note, making
6795 a new one if one does not already exist. */
6797 XEXP (tem, 0) = src_const;
6799 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_EQUAL,
6800 src_const, REG_NOTES (insn));
6802 /* If storing a constant value in a register that
6803 previously held the constant value 0,
6804 record this fact with a REG_WAS_0 note on this insn.
6806 Note that the *register* is required to have previously held 0,
6807 not just any register in the quantity and we must point to the
6808 insn that set that register to zero.
6810 Rather than track each register individually, we just see if
6811 the last set for this quantity was for this register. */
6813 if (REGNO_QTY_VALID_P (REGNO (dest))
6814 && qty_const[reg_qty[REGNO (dest)]] == const0_rtx)
6816 /* See if we previously had a REG_WAS_0 note. */
6817 rtx note = find_reg_note (insn, REG_WAS_0, NULL_RTX);
6818 rtx const_insn = qty_const_insn[reg_qty[REGNO (dest)]];
6820 if ((tem = single_set (const_insn)) != 0
6821 && rtx_equal_p (SET_DEST (tem), dest))
6824 XEXP (note, 0) = const_insn;
6826 REG_NOTES (insn) = gen_rtx (INSN_LIST, REG_WAS_0,
6827 const_insn, REG_NOTES (insn));
6832 /* Now deal with the destination. */
6834 sets[i].inner_dest_loc = &SET_DEST (sets[0].rtl);
6836 /* Look within any SIGN_EXTRACT or ZERO_EXTRACT
6837 to the MEM or REG within it. */
6838 while (GET_CODE (dest) == SIGN_EXTRACT
6839 || GET_CODE (dest) == ZERO_EXTRACT
6840 || GET_CODE (dest) == SUBREG
6841 || GET_CODE (dest) == STRICT_LOW_PART)
6843 sets[i].inner_dest_loc = &XEXP (dest, 0);
6844 dest = XEXP (dest, 0);
6847 sets[i].inner_dest = dest;
6849 if (GET_CODE (dest) == MEM)
6851 dest = fold_rtx (dest, insn);
6853 /* Decide whether we invalidate everything in memory,
6854 or just things at non-fixed places.
6855 Writing a large aggregate must invalidate everything
6856 because we don't know how long it is. */
6857 note_mem_written (dest, &writes_memory);
6860 /* Compute the hash code of the destination now,
6861 before the effects of this instruction are recorded,
6862 since the register values used in the address computation
6863 are those before this instruction. */
6864 sets[i].dest_hash = HASH (dest, mode);
6866 /* Don't enter a bit-field in the hash table
6867 because the value in it after the store
6868 may not equal what was stored, due to truncation. */
6870 if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT
6871 || GET_CODE (SET_DEST (sets[i].rtl)) == SIGN_EXTRACT)
6873 rtx width = XEXP (SET_DEST (sets[i].rtl), 1);
6875 if (src_const != 0 && GET_CODE (src_const) == CONST_INT
6876 && GET_CODE (width) == CONST_INT
6877 && INTVAL (width) < HOST_BITS_PER_WIDE_INT
6878 && ! (INTVAL (src_const)
6879 & ((HOST_WIDE_INT) (-1) << INTVAL (width))))
6880 /* Exception: if the value is constant,
6881 and it won't be truncated, record it. */
6885 /* This is chosen so that the destination will be invalidated
6886 but no new value will be recorded.
6887 We must invalidate because sometimes constant
6888 values can be recorded for bitfields. */
6889 sets[i].src_elt = 0;
6890 sets[i].src_volatile = 1;
6896 /* If only one set in a JUMP_INSN and it is now a no-op, we can delete
6898 else if (n_sets == 1 && dest == pc_rtx && src == pc_rtx)
6900 PUT_CODE (insn, NOTE);
6901 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
6902 NOTE_SOURCE_FILE (insn) = 0;
6903 cse_jumps_altered = 1;
6904 /* One less use of the label this insn used to jump to. */
6905 --LABEL_NUSES (JUMP_LABEL (insn));
6906 /* No more processing for this set. */
6910 /* If this SET is now setting PC to a label, we know it used to
6911 be a conditional or computed branch. So we see if we can follow
6912 it. If it was a computed branch, delete it and re-emit. */
6913 else if (dest == pc_rtx && GET_CODE (src) == LABEL_REF)
6917 /* If this is not in the format for a simple branch and
6918 we are the only SET in it, re-emit it. */
6919 if (! simplejump_p (insn) && n_sets == 1)
6921 rtx new = emit_jump_insn_before (gen_jump (XEXP (src, 0)), insn);
6922 JUMP_LABEL (new) = XEXP (src, 0);
6923 LABEL_NUSES (XEXP (src, 0))++;
6928 /* Otherwise, force rerecognition, since it probably had
6929 a different pattern before.
6930 This shouldn't really be necessary, since whatever
6931 changed the source value above should have done this.
6932 Until the right place is found, might as well do this here. */
6933 INSN_CODE (insn) = -1;
6935 /* Now that we've converted this jump to an unconditional jump,
6936 there is dead code after it. Delete the dead code until we
6937 reach a BARRIER, the end of the function, or a label. Do
6938 not delete NOTEs except for NOTE_INSN_DELETED since later
6939 phases assume these notes are retained. */
6943 while (NEXT_INSN (p) != 0
6944 && GET_CODE (NEXT_INSN (p)) != BARRIER
6945 && GET_CODE (NEXT_INSN (p)) != CODE_LABEL)
6947 if (GET_CODE (NEXT_INSN (p)) != NOTE
6948 || NOTE_LINE_NUMBER (NEXT_INSN (p)) == NOTE_INSN_DELETED)
6949 delete_insn (NEXT_INSN (p));
6954 /* If we don't have a BARRIER immediately after INSN, put one there.
6955 Much code assumes that there are no NOTEs between a JUMP_INSN and
6958 if (NEXT_INSN (insn) == 0
6959 || GET_CODE (NEXT_INSN (insn)) != BARRIER)
6960 emit_barrier_after (insn);
6962 /* We might have two BARRIERs separated by notes. Delete the second
6965 if (p != insn && NEXT_INSN (p) != 0
6966 && GET_CODE (NEXT_INSN (p)) == BARRIER)
6967 delete_insn (NEXT_INSN (p));
6969 cse_jumps_altered = 1;
6973 /* If destination is volatile, invalidate it and then do no further
6974 processing for this assignment. */
6976 else if (do_not_record)
6978 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG
6979 || GET_CODE (dest) == MEM)
6980 invalidate (dest, VOIDmode);
6981 else if (GET_CODE (dest) == STRICT_LOW_PART
6982 || GET_CODE (dest) == ZERO_EXTRACT)
6983 invalidate (XEXP (dest, 0), GET_MODE (dest));
6987 if (sets[i].rtl != 0 && dest != SET_DEST (sets[i].rtl))
6988 sets[i].dest_hash = HASH (SET_DEST (sets[i].rtl), mode);
6991 /* If setting CC0, record what it was set to, or a constant, if it
6992 is equivalent to a constant. If it is being set to a floating-point
6993 value, make a COMPARE with the appropriate constant of 0. If we
6994 don't do this, later code can interpret this as a test against
6995 const0_rtx, which can cause problems if we try to put it into an
6996 insn as a floating-point operand. */
6997 if (dest == cc0_rtx)
6999 this_insn_cc0 = src_const && mode != VOIDmode ? src_const : src;
7000 this_insn_cc0_mode = mode;
7001 if (FLOAT_MODE_P (mode))
7002 this_insn_cc0 = gen_rtx (COMPARE, VOIDmode, this_insn_cc0,
7008 /* Now enter all non-volatile source expressions in the hash table
7009 if they are not already present.
7010 Record their equivalence classes in src_elt.
7011 This way we can insert the corresponding destinations into
7012 the same classes even if the actual sources are no longer in them
7013 (having been invalidated). */
7015 if (src_eqv && src_eqv_elt == 0 && sets[0].rtl != 0 && ! src_eqv_volatile
7016 && ! rtx_equal_p (src_eqv, SET_DEST (sets[0].rtl)))
7018 register struct table_elt *elt;
7019 register struct table_elt *classp = sets[0].src_elt;
7020 rtx dest = SET_DEST (sets[0].rtl);
7021 enum machine_mode eqvmode = GET_MODE (dest);
7023 if (GET_CODE (dest) == STRICT_LOW_PART)
7025 eqvmode = GET_MODE (SUBREG_REG (XEXP (dest, 0)));
7028 if (insert_regs (src_eqv, classp, 0))
7029 src_eqv_hash = HASH (src_eqv, eqvmode);
7030 elt = insert (src_eqv, classp, src_eqv_hash, eqvmode);
7031 elt->in_memory = src_eqv_in_memory;
7032 elt->in_struct = src_eqv_in_struct;
7035 /* Check to see if src_eqv_elt is the same as a set source which
7036 does not yet have an elt, and if so set the elt of the set source
7038 for (i = 0; i < n_sets; i++)
7039 if (sets[i].rtl && sets[i].src_elt == 0
7040 && rtx_equal_p (SET_SRC (sets[i].rtl), src_eqv))
7041 sets[i].src_elt = src_eqv_elt;
7044 for (i = 0; i < n_sets; i++)
7045 if (sets[i].rtl && ! sets[i].src_volatile
7046 && ! rtx_equal_p (SET_SRC (sets[i].rtl), SET_DEST (sets[i].rtl)))
7048 if (GET_CODE (SET_DEST (sets[i].rtl)) == STRICT_LOW_PART)
7050 /* REG_EQUAL in setting a STRICT_LOW_PART
7051 gives an equivalent for the entire destination register,
7052 not just for the subreg being stored in now.
7053 This is a more interesting equivalence, so we arrange later
7054 to treat the entire reg as the destination. */
7055 sets[i].src_elt = src_eqv_elt;
7056 sets[i].src_hash = src_eqv_hash;
7060 /* Insert source and constant equivalent into hash table, if not
7062 register struct table_elt *classp = src_eqv_elt;
7063 register rtx src = sets[i].src;
7064 register rtx dest = SET_DEST (sets[i].rtl);
7065 enum machine_mode mode
7066 = GET_MODE (src) == VOIDmode ? GET_MODE (dest) : GET_MODE (src);
7068 if (sets[i].src_elt == 0)
7070 register struct table_elt *elt;
7072 /* Note that these insert_regs calls cannot remove
7073 any of the src_elt's, because they would have failed to
7074 match if not still valid. */
7075 if (insert_regs (src, classp, 0))
7076 sets[i].src_hash = HASH (src, mode);
7077 elt = insert (src, classp, sets[i].src_hash, mode);
7078 elt->in_memory = sets[i].src_in_memory;
7079 elt->in_struct = sets[i].src_in_struct;
7080 sets[i].src_elt = classp = elt;
7083 if (sets[i].src_const && sets[i].src_const_elt == 0
7084 && src != sets[i].src_const
7085 && ! rtx_equal_p (sets[i].src_const, src))
7086 sets[i].src_elt = insert (sets[i].src_const, classp,
7087 sets[i].src_const_hash, mode);
7090 else if (sets[i].src_elt == 0)
7091 /* If we did not insert the source into the hash table (e.g., it was
7092 volatile), note the equivalence class for the REG_EQUAL value, if any,
7093 so that the destination goes into that class. */
7094 sets[i].src_elt = src_eqv_elt;
7096 invalidate_from_clobbers (&writes_memory, x);
7098 /* Some registers are invalidated by subroutine calls. Memory is
7099 invalidated by non-constant calls. */
7101 if (GET_CODE (insn) == CALL_INSN)
7103 static struct write_data everything = {0, 1, 1, 1};
7105 if (! CONST_CALL_P (insn))
7106 invalidate_memory (&everything);
7107 invalidate_for_call ();
7110 /* Now invalidate everything set by this instruction.
7111 If a SUBREG or other funny destination is being set,
7112 sets[i].rtl is still nonzero, so here we invalidate the reg
7113 a part of which is being set. */
7115 for (i = 0; i < n_sets; i++)
7118 /* We can't use the inner dest, because the mode associated with
7119 a ZERO_EXTRACT is significant. */
7120 register rtx dest = SET_DEST (sets[i].rtl);
7122 /* Needed for registers to remove the register from its
7123 previous quantity's chain.
7124 Needed for memory if this is a nonvarying address, unless
7125 we have just done an invalidate_memory that covers even those. */
7126 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG
7127 || (GET_CODE (dest) == MEM && ! writes_memory.all
7128 && ! cse_rtx_addr_varies_p (dest)))
7129 invalidate (dest, VOIDmode);
7130 else if (GET_CODE (dest) == STRICT_LOW_PART
7131 || GET_CODE (dest) == ZERO_EXTRACT)
7132 invalidate (XEXP (dest, 0), GET_MODE (dest));
7135 /* Make sure registers mentioned in destinations
7136 are safe for use in an expression to be inserted.
7137 This removes from the hash table
7138 any invalid entry that refers to one of these registers.
7140 We don't care about the return value from mention_regs because
7141 we are going to hash the SET_DEST values unconditionally. */
7143 for (i = 0; i < n_sets; i++)
7144 if (sets[i].rtl && GET_CODE (SET_DEST (sets[i].rtl)) != REG)
7145 mention_regs (SET_DEST (sets[i].rtl));
7147 /* We may have just removed some of the src_elt's from the hash table.
7148 So replace each one with the current head of the same class. */
7150 for (i = 0; i < n_sets; i++)
7153 if (sets[i].src_elt && sets[i].src_elt->first_same_value == 0)
7154 /* If elt was removed, find current head of same class,
7155 or 0 if nothing remains of that class. */
7157 register struct table_elt *elt = sets[i].src_elt;
7159 while (elt && elt->prev_same_value)
7160 elt = elt->prev_same_value;
7162 while (elt && elt->first_same_value == 0)
7163 elt = elt->next_same_value;
7164 sets[i].src_elt = elt ? elt->first_same_value : 0;
7168 /* Now insert the destinations into their equivalence classes. */
7170 for (i = 0; i < n_sets; i++)
7173 register rtx dest = SET_DEST (sets[i].rtl);
7174 register struct table_elt *elt;
7176 /* Don't record value if we are not supposed to risk allocating
7177 floating-point values in registers that might be wider than
7179 if ((flag_float_store
7180 && GET_CODE (dest) == MEM
7181 && FLOAT_MODE_P (GET_MODE (dest)))
7182 /* Don't record values of destinations set inside a libcall block
7183 since we might delete the libcall. Things should have been set
7184 up so we won't want to reuse such a value, but we play it safe
7187 /* If we didn't put a REG_EQUAL value or a source into the hash
7188 table, there is no point is recording DEST. */
7189 || sets[i].src_elt == 0)
7192 /* STRICT_LOW_PART isn't part of the value BEING set,
7193 and neither is the SUBREG inside it.
7194 Note that in this case SETS[I].SRC_ELT is really SRC_EQV_ELT. */
7195 if (GET_CODE (dest) == STRICT_LOW_PART)
7196 dest = SUBREG_REG (XEXP (dest, 0));
7198 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG)
7199 /* Registers must also be inserted into chains for quantities. */
7200 if (insert_regs (dest, sets[i].src_elt, 1))
7201 /* If `insert_regs' changes something, the hash code must be
7203 sets[i].dest_hash = HASH (dest, GET_MODE (dest));
7205 elt = insert (dest, sets[i].src_elt,
7206 sets[i].dest_hash, GET_MODE (dest));
7207 elt->in_memory = GET_CODE (sets[i].inner_dest) == MEM;
7210 /* This implicitly assumes a whole struct
7211 need not have MEM_IN_STRUCT_P.
7212 But a whole struct is *supposed* to have MEM_IN_STRUCT_P. */
7213 elt->in_struct = (MEM_IN_STRUCT_P (sets[i].inner_dest)
7214 || sets[i].inner_dest != SET_DEST (sets[i].rtl));
7217 /* If we have (set (subreg:m1 (reg:m2 foo) 0) (bar:m1)), M1 is no
7218 narrower than M2, and both M1 and M2 are the same number of words,
7219 we are also doing (set (reg:m2 foo) (subreg:m2 (bar:m1) 0)) so
7220 make that equivalence as well.
7222 However, BAR may have equivalences for which gen_lowpart_if_possible
7223 will produce a simpler value than gen_lowpart_if_possible applied to
7224 BAR (e.g., if BAR was ZERO_EXTENDed from M2), so we will scan all
7225 BAR's equivalences. If we don't get a simplified form, make
7226 the SUBREG. It will not be used in an equivalence, but will
7227 cause two similar assignments to be detected.
7229 Note the loop below will find SUBREG_REG (DEST) since we have
7230 already entered SRC and DEST of the SET in the table. */
7232 if (GET_CODE (dest) == SUBREG
7233 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))) - 1)
7235 == (GET_MODE_SIZE (GET_MODE (dest)) - 1)/ UNITS_PER_WORD)
7236 && (GET_MODE_SIZE (GET_MODE (dest))
7237 >= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))))
7238 && sets[i].src_elt != 0)
7240 enum machine_mode new_mode = GET_MODE (SUBREG_REG (dest));
7241 struct table_elt *elt, *classp = 0;
7243 for (elt = sets[i].src_elt->first_same_value; elt;
7244 elt = elt->next_same_value)
7248 struct table_elt *src_elt;
7250 /* Ignore invalid entries. */
7251 if (GET_CODE (elt->exp) != REG
7252 && ! exp_equiv_p (elt->exp, elt->exp, 1, 0))
7255 new_src = gen_lowpart_if_possible (new_mode, elt->exp);
7257 new_src = gen_rtx (SUBREG, new_mode, elt->exp, 0);
7259 src_hash = HASH (new_src, new_mode);
7260 src_elt = lookup (new_src, src_hash, new_mode);
7262 /* Put the new source in the hash table is if isn't
7266 if (insert_regs (new_src, classp, 0))
7267 src_hash = HASH (new_src, new_mode);
7268 src_elt = insert (new_src, classp, src_hash, new_mode);
7269 src_elt->in_memory = elt->in_memory;
7270 src_elt->in_struct = elt->in_struct;
7272 else if (classp && classp != src_elt->first_same_value)
7273 /* Show that two things that we've seen before are
7274 actually the same. */
7275 merge_equiv_classes (src_elt, classp);
7277 classp = src_elt->first_same_value;
7282 /* Special handling for (set REG0 REG1)
7283 where REG0 is the "cheapest", cheaper than REG1.
7284 After cse, REG1 will probably not be used in the sequel,
7285 so (if easily done) change this insn to (set REG1 REG0) and
7286 replace REG1 with REG0 in the previous insn that computed their value.
7287 Then REG1 will become a dead store and won't cloud the situation
7288 for later optimizations.
7290 Do not make this change if REG1 is a hard register, because it will
7291 then be used in the sequel and we may be changing a two-operand insn
7292 into a three-operand insn.
7294 Also do not do this if we are operating on a copy of INSN. */
7296 if (n_sets == 1 && sets[0].rtl && GET_CODE (SET_DEST (sets[0].rtl)) == REG
7297 && NEXT_INSN (PREV_INSN (insn)) == insn
7298 && GET_CODE (SET_SRC (sets[0].rtl)) == REG
7299 && REGNO (SET_SRC (sets[0].rtl)) >= FIRST_PSEUDO_REGISTER
7300 && REGNO_QTY_VALID_P (REGNO (SET_SRC (sets[0].rtl)))
7301 && (qty_first_reg[reg_qty[REGNO (SET_SRC (sets[0].rtl))]]
7302 == REGNO (SET_DEST (sets[0].rtl))))
7304 rtx prev = PREV_INSN (insn);
7305 while (prev && GET_CODE (prev) == NOTE)
7306 prev = PREV_INSN (prev);
7308 if (prev && GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SET
7309 && SET_DEST (PATTERN (prev)) == SET_SRC (sets[0].rtl))
7311 rtx dest = SET_DEST (sets[0].rtl);
7312 rtx note = find_reg_note (prev, REG_EQUIV, NULL_RTX);
7314 validate_change (prev, & SET_DEST (PATTERN (prev)), dest, 1);
7315 validate_change (insn, & SET_DEST (sets[0].rtl),
7316 SET_SRC (sets[0].rtl), 1);
7317 validate_change (insn, & SET_SRC (sets[0].rtl), dest, 1);
7318 apply_change_group ();
7320 /* If REG1 was equivalent to a constant, REG0 is not. */
7322 PUT_REG_NOTE_KIND (note, REG_EQUAL);
7324 /* If there was a REG_WAS_0 note on PREV, remove it. Move
7325 any REG_WAS_0 note on INSN to PREV. */
7326 note = find_reg_note (prev, REG_WAS_0, NULL_RTX);
7328 remove_note (prev, note);
7330 note = find_reg_note (insn, REG_WAS_0, NULL_RTX);
7333 remove_note (insn, note);
7334 XEXP (note, 1) = REG_NOTES (prev);
7335 REG_NOTES (prev) = note;
7340 /* If this is a conditional jump insn, record any known equivalences due to
7341 the condition being tested. */
7343 last_jump_equiv_class = 0;
7344 if (GET_CODE (insn) == JUMP_INSN
7345 && n_sets == 1 && GET_CODE (x) == SET
7346 && GET_CODE (SET_SRC (x)) == IF_THEN_ELSE)
7347 record_jump_equiv (insn, 0);
7350 /* If the previous insn set CC0 and this insn no longer references CC0,
7351 delete the previous insn. Here we use the fact that nothing expects CC0
7352 to be valid over an insn, which is true until the final pass. */
7353 if (prev_insn && GET_CODE (prev_insn) == INSN
7354 && (tem = single_set (prev_insn)) != 0
7355 && SET_DEST (tem) == cc0_rtx
7356 && ! reg_mentioned_p (cc0_rtx, x))
7358 PUT_CODE (prev_insn, NOTE);
7359 NOTE_LINE_NUMBER (prev_insn) = NOTE_INSN_DELETED;
7360 NOTE_SOURCE_FILE (prev_insn) = 0;
7363 prev_insn_cc0 = this_insn_cc0;
7364 prev_insn_cc0_mode = this_insn_cc0_mode;
7370 /* Store 1 in *WRITES_PTR for those categories of memory ref
7371 that must be invalidated when the expression WRITTEN is stored in.
7372 If WRITTEN is null, say everything must be invalidated. */
7375 note_mem_written (written, writes_ptr)
7377 struct write_data *writes_ptr;
7379 static struct write_data everything = {0, 1, 1, 1};
7382 *writes_ptr = everything;
7383 else if (GET_CODE (written) == MEM)
7385 /* Pushing or popping the stack invalidates just the stack pointer. */
7386 rtx addr = XEXP (written, 0);
7387 if ((GET_CODE (addr) == PRE_DEC || GET_CODE (addr) == PRE_INC
7388 || GET_CODE (addr) == POST_DEC || GET_CODE (addr) == POST_INC)
7389 && GET_CODE (XEXP (addr, 0)) == REG
7390 && REGNO (XEXP (addr, 0)) == STACK_POINTER_REGNUM)
7395 else if (GET_MODE (written) == BLKmode)
7396 *writes_ptr = everything;
7397 /* (mem (scratch)) means clobber everything. */
7398 else if (GET_CODE (addr) == SCRATCH)
7399 *writes_ptr = everything;
7400 else if (cse_rtx_addr_varies_p (written))
7402 /* A varying address that is a sum indicates an array element,
7403 and that's just as good as a structure element
7404 in implying that we need not invalidate scalar variables.
7405 However, we must allow QImode aliasing of scalars, because the
7406 ANSI C standard allows character pointers to alias anything. */
7407 if (! ((MEM_IN_STRUCT_P (written)
7408 || GET_CODE (XEXP (written, 0)) == PLUS)
7409 && GET_MODE (written) != QImode))
7410 writes_ptr->all = 1;
7411 writes_ptr->nonscalar = 1;
7413 writes_ptr->var = 1;
7417 /* Perform invalidation on the basis of everything about an insn
7418 except for invalidating the actual places that are SET in it.
7419 This includes the places CLOBBERed, and anything that might
7420 alias with something that is SET or CLOBBERed.
7422 W points to the writes_memory for this insn, a struct write_data
7423 saying which kinds of memory references must be invalidated.
7424 X is the pattern of the insn. */
7427 invalidate_from_clobbers (w, x)
7428 struct write_data *w;
7431 /* If W->var is not set, W specifies no action.
7432 If W->all is set, this step gets all memory refs
7433 so they can be ignored in the rest of this function. */
7435 invalidate_memory (w);
7439 if (reg_tick[STACK_POINTER_REGNUM] >= 0)
7440 reg_tick[STACK_POINTER_REGNUM]++;
7442 /* This should be *very* rare. */
7443 if (TEST_HARD_REG_BIT (hard_regs_in_table, STACK_POINTER_REGNUM))
7444 invalidate (stack_pointer_rtx, VOIDmode);
7447 if (GET_CODE (x) == CLOBBER)
7449 rtx ref = XEXP (x, 0);
7452 if (GET_CODE (ref) == REG || GET_CODE (ref) == SUBREG
7453 || (GET_CODE (ref) == MEM && ! w->all))
7454 invalidate (ref, VOIDmode);
7455 else if (GET_CODE (ref) == STRICT_LOW_PART
7456 || GET_CODE (ref) == ZERO_EXTRACT)
7457 invalidate (XEXP (ref, 0), GET_MODE (ref));
7460 else if (GET_CODE (x) == PARALLEL)
7463 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
7465 register rtx y = XVECEXP (x, 0, i);
7466 if (GET_CODE (y) == CLOBBER)
7468 rtx ref = XEXP (y, 0);
7471 if (GET_CODE (ref) == REG || GET_CODE (ref) == SUBREG
7472 || (GET_CODE (ref) == MEM && !w->all))
7473 invalidate (ref, VOIDmode);
7474 else if (GET_CODE (ref) == STRICT_LOW_PART
7475 || GET_CODE (ref) == ZERO_EXTRACT)
7476 invalidate (XEXP (ref, 0), GET_MODE (ref));
7483 /* Process X, part of the REG_NOTES of an insn. Look at any REG_EQUAL notes
7484 and replace any registers in them with either an equivalent constant
7485 or the canonical form of the register. If we are inside an address,
7486 only do this if the address remains valid.
7488 OBJECT is 0 except when within a MEM in which case it is the MEM.
7490 Return the replacement for X. */
7493 cse_process_notes (x, object)
7497 enum rtx_code code = GET_CODE (x);
7498 char *fmt = GET_RTX_FORMAT (code);
7514 XEXP (x, 0) = cse_process_notes (XEXP (x, 0), x);
7519 if (REG_NOTE_KIND (x) == REG_EQUAL)
7520 XEXP (x, 0) = cse_process_notes (XEXP (x, 0), NULL_RTX);
7522 XEXP (x, 1) = cse_process_notes (XEXP (x, 1), NULL_RTX);
7528 rtx new = cse_process_notes (XEXP (x, 0), object);
7529 /* We don't substitute VOIDmode constants into these rtx,
7530 since they would impede folding. */
7531 if (GET_MODE (new) != VOIDmode)
7532 validate_change (object, &XEXP (x, 0), new, 0);
7537 i = reg_qty[REGNO (x)];
7539 /* Return a constant or a constant register. */
7540 if (REGNO_QTY_VALID_P (REGNO (x))
7541 && qty_const[i] != 0
7542 && (CONSTANT_P (qty_const[i])
7543 || GET_CODE (qty_const[i]) == REG))
7545 rtx new = gen_lowpart_if_possible (GET_MODE (x), qty_const[i]);
7550 /* Otherwise, canonicalize this register. */
7551 return canon_reg (x, NULL_RTX);
7554 for (i = 0; i < GET_RTX_LENGTH (code); i++)
7556 validate_change (object, &XEXP (x, i),
7557 cse_process_notes (XEXP (x, i), object), 0);
7562 /* Find common subexpressions between the end test of a loop and the beginning
7563 of the loop. LOOP_START is the CODE_LABEL at the start of a loop.
7565 Often we have a loop where an expression in the exit test is used
7566 in the body of the loop. For example "while (*p) *q++ = *p++;".
7567 Because of the way we duplicate the loop exit test in front of the loop,
7568 however, we don't detect that common subexpression. This will be caught
7569 when global cse is implemented, but this is a quite common case.
7571 This function handles the most common cases of these common expressions.
7572 It is called after we have processed the basic block ending with the
7573 NOTE_INSN_LOOP_END note that ends a loop and the previous JUMP_INSN
7574 jumps to a label used only once. */
7577 cse_around_loop (loop_start)
7582 struct table_elt *p;
7584 /* If the jump at the end of the loop doesn't go to the start, we don't
7586 for (insn = PREV_INSN (loop_start);
7587 insn && (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0);
7588 insn = PREV_INSN (insn))
7592 || GET_CODE (insn) != NOTE
7593 || NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG)
7596 /* If the last insn of the loop (the end test) was an NE comparison,
7597 we will interpret it as an EQ comparison, since we fell through
7598 the loop. Any equivalences resulting from that comparison are
7599 therefore not valid and must be invalidated. */
7600 if (last_jump_equiv_class)
7601 for (p = last_jump_equiv_class->first_same_value; p;
7602 p = p->next_same_value)
7603 if (GET_CODE (p->exp) == MEM || GET_CODE (p->exp) == REG
7604 || (GET_CODE (p->exp) == SUBREG
7605 && GET_CODE (SUBREG_REG (p->exp)) == REG))
7606 invalidate (p->exp, VOIDmode);
7607 else if (GET_CODE (p->exp) == STRICT_LOW_PART
7608 || GET_CODE (p->exp) == ZERO_EXTRACT)
7609 invalidate (XEXP (p->exp, 0), GET_MODE (p->exp));
7611 /* Process insns starting after LOOP_START until we hit a CALL_INSN or
7612 a CODE_LABEL (we could handle a CALL_INSN, but it isn't worth it).
7614 The only thing we do with SET_DEST is invalidate entries, so we
7615 can safely process each SET in order. It is slightly less efficient
7616 to do so, but we only want to handle the most common cases. */
7618 for (insn = NEXT_INSN (loop_start);
7619 GET_CODE (insn) != CALL_INSN && GET_CODE (insn) != CODE_LABEL
7620 && ! (GET_CODE (insn) == NOTE
7621 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
7622 insn = NEXT_INSN (insn))
7624 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
7625 && (GET_CODE (PATTERN (insn)) == SET
7626 || GET_CODE (PATTERN (insn)) == CLOBBER))
7627 cse_set_around_loop (PATTERN (insn), insn, loop_start);
7628 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
7629 && GET_CODE (PATTERN (insn)) == PARALLEL)
7630 for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
7631 if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == SET
7632 || GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == CLOBBER)
7633 cse_set_around_loop (XVECEXP (PATTERN (insn), 0, i), insn,
7638 /* Variable used for communications between the next two routines. */
7640 static struct write_data skipped_writes_memory;
7642 /* Process one SET of an insn that was skipped. We ignore CLOBBERs
7643 since they are done elsewhere. This function is called via note_stores. */
7646 invalidate_skipped_set (dest, set)
7650 if (GET_CODE (set) == CLOBBER
7657 if (GET_CODE (dest) == MEM)
7658 note_mem_written (dest, &skipped_writes_memory);
7660 /* There are times when an address can appear varying and be a PLUS
7661 during this scan when it would be a fixed address were we to know
7662 the proper equivalences. So promote "nonscalar" to be "all". */
7663 if (skipped_writes_memory.nonscalar)
7664 skipped_writes_memory.all = 1;
7666 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG
7667 || (! skipped_writes_memory.all && ! cse_rtx_addr_varies_p (dest)))
7668 invalidate (dest, VOIDmode);
7669 else if (GET_CODE (dest) == STRICT_LOW_PART
7670 || GET_CODE (dest) == ZERO_EXTRACT)
7671 invalidate (XEXP (dest, 0), GET_MODE (dest));
7674 /* Invalidate all insns from START up to the end of the function or the
7675 next label. This called when we wish to CSE around a block that is
7676 conditionally executed. */
7679 invalidate_skipped_block (start)
7683 static struct write_data init = {0, 0, 0, 0};
7684 static struct write_data everything = {0, 1, 1, 1};
7686 for (insn = start; insn && GET_CODE (insn) != CODE_LABEL;
7687 insn = NEXT_INSN (insn))
7689 if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
7692 skipped_writes_memory = init;
7694 if (GET_CODE (insn) == CALL_INSN)
7696 invalidate_for_call ();
7697 skipped_writes_memory = everything;
7700 note_stores (PATTERN (insn), invalidate_skipped_set);
7701 invalidate_from_clobbers (&skipped_writes_memory, PATTERN (insn));
7705 /* Used for communication between the following two routines; contains a
7706 value to be checked for modification. */
7708 static rtx cse_check_loop_start_value;
7710 /* If modifying X will modify the value in CSE_CHECK_LOOP_START_VALUE,
7711 indicate that fact by setting CSE_CHECK_LOOP_START_VALUE to 0. */
7714 cse_check_loop_start (x, set)
7718 if (cse_check_loop_start_value == 0
7719 || GET_CODE (x) == CC0 || GET_CODE (x) == PC)
7722 if ((GET_CODE (x) == MEM && GET_CODE (cse_check_loop_start_value) == MEM)
7723 || reg_overlap_mentioned_p (x, cse_check_loop_start_value))
7724 cse_check_loop_start_value = 0;
7727 /* X is a SET or CLOBBER contained in INSN that was found near the start of
7728 a loop that starts with the label at LOOP_START.
7730 If X is a SET, we see if its SET_SRC is currently in our hash table.
7731 If so, we see if it has a value equal to some register used only in the
7732 loop exit code (as marked by jump.c).
7734 If those two conditions are true, we search backwards from the start of
7735 the loop to see if that same value was loaded into a register that still
7736 retains its value at the start of the loop.
7738 If so, we insert an insn after the load to copy the destination of that
7739 load into the equivalent register and (try to) replace our SET_SRC with that
7742 In any event, we invalidate whatever this SET or CLOBBER modifies. */
7745 cse_set_around_loop (x, insn, loop_start)
7750 struct table_elt *src_elt;
7751 static struct write_data init = {0, 0, 0, 0};
7752 struct write_data writes_memory;
7754 writes_memory = init;
7756 /* If this is a SET, see if we can replace SET_SRC, but ignore SETs that
7757 are setting PC or CC0 or whose SET_SRC is already a register. */
7758 if (GET_CODE (x) == SET
7759 && GET_CODE (SET_DEST (x)) != PC && GET_CODE (SET_DEST (x)) != CC0
7760 && GET_CODE (SET_SRC (x)) != REG)
7762 src_elt = lookup (SET_SRC (x),
7763 HASH (SET_SRC (x), GET_MODE (SET_DEST (x))),
7764 GET_MODE (SET_DEST (x)));
7767 for (src_elt = src_elt->first_same_value; src_elt;
7768 src_elt = src_elt->next_same_value)
7769 if (GET_CODE (src_elt->exp) == REG && REG_LOOP_TEST_P (src_elt->exp)
7770 && COST (src_elt->exp) < COST (SET_SRC (x)))
7774 /* Look for an insn in front of LOOP_START that sets
7775 something in the desired mode to SET_SRC (x) before we hit
7776 a label or CALL_INSN. */
7778 for (p = prev_nonnote_insn (loop_start);
7779 p && GET_CODE (p) != CALL_INSN
7780 && GET_CODE (p) != CODE_LABEL;
7781 p = prev_nonnote_insn (p))
7782 if ((set = single_set (p)) != 0
7783 && GET_CODE (SET_DEST (set)) == REG
7784 && GET_MODE (SET_DEST (set)) == src_elt->mode
7785 && rtx_equal_p (SET_SRC (set), SET_SRC (x)))
7787 /* We now have to ensure that nothing between P
7788 and LOOP_START modified anything referenced in
7789 SET_SRC (x). We know that nothing within the loop
7790 can modify it, or we would have invalidated it in
7794 cse_check_loop_start_value = SET_SRC (x);
7795 for (q = p; q != loop_start; q = NEXT_INSN (q))
7796 if (GET_RTX_CLASS (GET_CODE (q)) == 'i')
7797 note_stores (PATTERN (q), cse_check_loop_start);
7799 /* If nothing was changed and we can replace our
7800 SET_SRC, add an insn after P to copy its destination
7801 to what we will be replacing SET_SRC with. */
7802 if (cse_check_loop_start_value
7803 && validate_change (insn, &SET_SRC (x),
7805 emit_insn_after (gen_move_insn (src_elt->exp,
7813 /* Now invalidate anything modified by X. */
7814 note_mem_written (SET_DEST (x), &writes_memory);
7816 if (writes_memory.var)
7817 invalidate_memory (&writes_memory);
7819 /* See comment on similar code in cse_insn for explanation of these tests. */
7820 if (GET_CODE (SET_DEST (x)) == REG || GET_CODE (SET_DEST (x)) == SUBREG
7821 || (GET_CODE (SET_DEST (x)) == MEM && ! writes_memory.all
7822 && ! cse_rtx_addr_varies_p (SET_DEST (x))))
7823 invalidate (SET_DEST (x), VOIDmode);
7824 else if (GET_CODE (SET_DEST (x)) == STRICT_LOW_PART
7825 || GET_CODE (SET_DEST (x)) == ZERO_EXTRACT)
7826 invalidate (XEXP (SET_DEST (x), 0), GET_MODE (SET_DEST (x)));
7829 /* Find the end of INSN's basic block and return its range,
7830 the total number of SETs in all the insns of the block, the last insn of the
7831 block, and the branch path.
7833 The branch path indicates which branches should be followed. If a non-zero
7834 path size is specified, the block should be rescanned and a different set
7835 of branches will be taken. The branch path is only used if
7836 FLAG_CSE_FOLLOW_JUMPS or FLAG_CSE_SKIP_BLOCKS is non-zero.
7838 DATA is a pointer to a struct cse_basic_block_data, defined below, that is
7839 used to describe the block. It is filled in with the information about
7840 the current block. The incoming structure's branch path, if any, is used
7841 to construct the output branch path. */
7844 cse_end_of_basic_block (insn, data, follow_jumps, after_loop, skip_blocks)
7846 struct cse_basic_block_data *data;
7853 int low_cuid = INSN_CUID (insn), high_cuid = INSN_CUID (insn);
7854 rtx next = GET_RTX_CLASS (GET_CODE (insn)) == 'i' ? insn : next_real_insn (insn);
7855 int path_size = data->path_size;
7859 /* Update the previous branch path, if any. If the last branch was
7860 previously TAKEN, mark it NOT_TAKEN. If it was previously NOT_TAKEN,
7861 shorten the path by one and look at the previous branch. We know that
7862 at least one branch must have been taken if PATH_SIZE is non-zero. */
7863 while (path_size > 0)
7865 if (data->path[path_size - 1].status != NOT_TAKEN)
7867 data->path[path_size - 1].status = NOT_TAKEN;
7874 /* Scan to end of this basic block. */
7875 while (p && GET_CODE (p) != CODE_LABEL)
7877 /* Don't cse out the end of a loop. This makes a difference
7878 only for the unusual loops that always execute at least once;
7879 all other loops have labels there so we will stop in any case.
7880 Cse'ing out the end of the loop is dangerous because it
7881 might cause an invariant expression inside the loop
7882 to be reused after the end of the loop. This would make it
7883 hard to move the expression out of the loop in loop.c,
7884 especially if it is one of several equivalent expressions
7885 and loop.c would like to eliminate it.
7887 If we are running after loop.c has finished, we can ignore
7888 the NOTE_INSN_LOOP_END. */
7890 if (! after_loop && GET_CODE (p) == NOTE
7891 && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END)
7894 /* Don't cse over a call to setjmp; on some machines (eg vax)
7895 the regs restored by the longjmp come from
7896 a later time than the setjmp. */
7897 if (GET_CODE (p) == NOTE
7898 && NOTE_LINE_NUMBER (p) == NOTE_INSN_SETJMP)
7901 /* A PARALLEL can have lots of SETs in it,
7902 especially if it is really an ASM_OPERANDS. */
7903 if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
7904 && GET_CODE (PATTERN (p)) == PARALLEL)
7905 nsets += XVECLEN (PATTERN (p), 0);
7906 else if (GET_CODE (p) != NOTE)
7909 /* Ignore insns made by CSE; they cannot affect the boundaries of
7912 if (INSN_UID (p) <= max_uid && INSN_CUID (p) > high_cuid)
7913 high_cuid = INSN_CUID (p);
7914 if (INSN_UID (p) <= max_uid && INSN_CUID (p) < low_cuid)
7915 low_cuid = INSN_CUID (p);
7917 /* See if this insn is in our branch path. If it is and we are to
7919 if (path_entry < path_size && data->path[path_entry].branch == p)
7921 if (data->path[path_entry].status != NOT_TAKEN)
7924 /* Point to next entry in path, if any. */
7928 /* If this is a conditional jump, we can follow it if -fcse-follow-jumps
7929 was specified, we haven't reached our maximum path length, there are
7930 insns following the target of the jump, this is the only use of the
7931 jump label, and the target label is preceded by a BARRIER.
7933 Alternatively, we can follow the jump if it branches around a
7934 block of code and there are no other branches into the block.
7935 In this case invalidate_skipped_block will be called to invalidate any
7936 registers set in the block when following the jump. */
7938 else if ((follow_jumps || skip_blocks) && path_size < PATHLENGTH - 1
7939 && GET_CODE (p) == JUMP_INSN
7940 && GET_CODE (PATTERN (p)) == SET
7941 && GET_CODE (SET_SRC (PATTERN (p))) == IF_THEN_ELSE
7942 && LABEL_NUSES (JUMP_LABEL (p)) == 1
7943 && NEXT_INSN (JUMP_LABEL (p)) != 0)
7945 for (q = PREV_INSN (JUMP_LABEL (p)); q; q = PREV_INSN (q))
7946 if ((GET_CODE (q) != NOTE
7947 || NOTE_LINE_NUMBER (q) == NOTE_INSN_LOOP_END
7948 || NOTE_LINE_NUMBER (q) == NOTE_INSN_SETJMP)
7949 && (GET_CODE (q) != CODE_LABEL || LABEL_NUSES (q) != 0))
7952 /* If we ran into a BARRIER, this code is an extension of the
7953 basic block when the branch is taken. */
7954 if (follow_jumps && q != 0 && GET_CODE (q) == BARRIER)
7956 /* Don't allow ourself to keep walking around an
7957 always-executed loop. */
7958 if (next_real_insn (q) == next)
7964 /* Similarly, don't put a branch in our path more than once. */
7965 for (i = 0; i < path_entry; i++)
7966 if (data->path[i].branch == p)
7969 if (i != path_entry)
7972 data->path[path_entry].branch = p;
7973 data->path[path_entry++].status = TAKEN;
7975 /* This branch now ends our path. It was possible that we
7976 didn't see this branch the last time around (when the
7977 insn in front of the target was a JUMP_INSN that was
7978 turned into a no-op). */
7979 path_size = path_entry;
7982 /* Mark block so we won't scan it again later. */
7983 PUT_MODE (NEXT_INSN (p), QImode);
7985 /* Detect a branch around a block of code. */
7986 else if (skip_blocks && q != 0 && GET_CODE (q) != CODE_LABEL)
7990 if (next_real_insn (q) == next)
7996 for (i = 0; i < path_entry; i++)
7997 if (data->path[i].branch == p)
8000 if (i != path_entry)
8003 /* This is no_labels_between_p (p, q) with an added check for
8004 reaching the end of a function (in case Q precedes P). */
8005 for (tmp = NEXT_INSN (p); tmp && tmp != q; tmp = NEXT_INSN (tmp))
8006 if (GET_CODE (tmp) == CODE_LABEL)
8011 data->path[path_entry].branch = p;
8012 data->path[path_entry++].status = AROUND;
8014 path_size = path_entry;
8017 /* Mark block so we won't scan it again later. */
8018 PUT_MODE (NEXT_INSN (p), QImode);
8025 data->low_cuid = low_cuid;
8026 data->high_cuid = high_cuid;
8027 data->nsets = nsets;
8030 /* If all jumps in the path are not taken, set our path length to zero
8031 so a rescan won't be done. */
8032 for (i = path_size - 1; i >= 0; i--)
8033 if (data->path[i].status != NOT_TAKEN)
8037 data->path_size = 0;
8039 data->path_size = path_size;
8041 /* End the current branch path. */
8042 data->path[path_size].branch = 0;
8045 /* Perform cse on the instructions of a function.
8046 F is the first instruction.
8047 NREGS is one plus the highest pseudo-reg number used in the instruction.
8049 AFTER_LOOP is 1 if this is the cse call done after loop optimization
8050 (only if -frerun-cse-after-loop).
8052 Returns 1 if jump_optimize should be redone due to simplifications
8053 in conditional jump instructions. */
8056 cse_main (f, nregs, after_loop, file)
8062 struct cse_basic_block_data val;
8063 register rtx insn = f;
8066 cse_jumps_altered = 0;
8067 constant_pool_entries_cost = 0;
8074 all_minus_one = (int *) alloca (nregs * sizeof (int));
8075 consec_ints = (int *) alloca (nregs * sizeof (int));
8077 for (i = 0; i < nregs; i++)
8079 all_minus_one[i] = -1;
8083 reg_next_eqv = (int *) alloca (nregs * sizeof (int));
8084 reg_prev_eqv = (int *) alloca (nregs * sizeof (int));
8085 reg_qty = (int *) alloca (nregs * sizeof (int));
8086 reg_in_table = (int *) alloca (nregs * sizeof (int));
8087 reg_tick = (int *) alloca (nregs * sizeof (int));
8089 #ifdef LOAD_EXTEND_OP
8091 /* Allocate scratch rtl here. cse_insn will fill in the memory reference
8092 and change the code and mode as appropriate. */
8093 memory_extend_rtx = gen_rtx (ZERO_EXTEND, VOIDmode, 0);
8096 /* Discard all the free elements of the previous function
8097 since they are allocated in the temporarily obstack. */
8098 bzero ((char *) table, sizeof table);
8099 free_element_chain = 0;
8100 n_elements_made = 0;
8102 /* Find the largest uid. */
8104 max_uid = get_max_uid ();
8105 uid_cuid = (int *) alloca ((max_uid + 1) * sizeof (int));
8106 bzero ((char *) uid_cuid, (max_uid + 1) * sizeof (int));
8108 /* Compute the mapping from uids to cuids.
8109 CUIDs are numbers assigned to insns, like uids,
8110 except that cuids increase monotonically through the code.
8111 Don't assign cuids to line-number NOTEs, so that the distance in cuids
8112 between two insns is not affected by -g. */
8114 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
8116 if (GET_CODE (insn) != NOTE
8117 || NOTE_LINE_NUMBER (insn) < 0)
8118 INSN_CUID (insn) = ++i;
8120 /* Give a line number note the same cuid as preceding insn. */
8121 INSN_CUID (insn) = i;
8124 /* Initialize which registers are clobbered by calls. */
8126 CLEAR_HARD_REG_SET (regs_invalidated_by_call);
8128 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
8129 if ((call_used_regs[i]
8130 /* Used to check !fixed_regs[i] here, but that isn't safe;
8131 fixed regs are still call-clobbered, and sched can get
8132 confused if they can "live across calls".
8134 The frame pointer is always preserved across calls. The arg
8135 pointer is if it is fixed. The stack pointer usually is, unless
8136 RETURN_POPS_ARGS, in which case an explicit CLOBBER
8137 will be present. If we are generating PIC code, the PIC offset
8138 table register is preserved across calls. */
8140 && i != STACK_POINTER_REGNUM
8141 && i != FRAME_POINTER_REGNUM
8142 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
8143 && i != HARD_FRAME_POINTER_REGNUM
8145 #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM
8146 && ! (i == ARG_POINTER_REGNUM && fixed_regs[i])
8148 #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED)
8149 && ! (i == PIC_OFFSET_TABLE_REGNUM && flag_pic)
8153 SET_HARD_REG_BIT (regs_invalidated_by_call, i);
8155 /* Loop over basic blocks.
8156 Compute the maximum number of qty's needed for each basic block
8157 (which is 2 for each SET). */
8161 cse_end_of_basic_block (insn, &val, flag_cse_follow_jumps, after_loop,
8162 flag_cse_skip_blocks);
8164 /* If this basic block was already processed or has no sets, skip it. */
8165 if (val.nsets == 0 || GET_MODE (insn) == QImode)
8167 PUT_MODE (insn, VOIDmode);
8168 insn = (val.last ? NEXT_INSN (val.last) : 0);
8173 cse_basic_block_start = val.low_cuid;
8174 cse_basic_block_end = val.high_cuid;
8175 max_qty = val.nsets * 2;
8178 fprintf (file, ";; Processing block from %d to %d, %d sets.\n",
8179 INSN_UID (insn), val.last ? INSN_UID (val.last) : 0,
8182 /* Make MAX_QTY bigger to give us room to optimize
8183 past the end of this basic block, if that should prove useful. */
8189 /* If this basic block is being extended by following certain jumps,
8190 (see `cse_end_of_basic_block'), we reprocess the code from the start.
8191 Otherwise, we start after this basic block. */
8192 if (val.path_size > 0)
8193 cse_basic_block (insn, val.last, val.path, 0);
8196 int old_cse_jumps_altered = cse_jumps_altered;
8199 /* When cse changes a conditional jump to an unconditional
8200 jump, we want to reprocess the block, since it will give
8201 us a new branch path to investigate. */
8202 cse_jumps_altered = 0;
8203 temp = cse_basic_block (insn, val.last, val.path, ! after_loop);
8204 if (cse_jumps_altered == 0
8205 || (flag_cse_follow_jumps == 0 && flag_cse_skip_blocks == 0))
8208 cse_jumps_altered |= old_cse_jumps_altered;
8216 /* Tell refers_to_mem_p that qty_const info is not available. */
8219 if (max_elements_made < n_elements_made)
8220 max_elements_made = n_elements_made;
8222 return cse_jumps_altered;
8225 /* Process a single basic block. FROM and TO and the limits of the basic
8226 block. NEXT_BRANCH points to the branch path when following jumps or
8227 a null path when not following jumps.
8229 AROUND_LOOP is non-zero if we are to try to cse around to the start of a
8230 loop. This is true when we are being called for the last time on a
8231 block and this CSE pass is before loop.c. */
8234 cse_basic_block (from, to, next_branch, around_loop)
8235 register rtx from, to;
8236 struct branch_path *next_branch;
8241 int in_libcall_block = 0;
8243 /* Each of these arrays is undefined before max_reg, so only allocate
8244 the space actually needed and adjust the start below. */
8246 qty_first_reg = (int *) alloca ((max_qty - max_reg) * sizeof (int));
8247 qty_last_reg = (int *) alloca ((max_qty - max_reg) * sizeof (int));
8248 qty_mode= (enum machine_mode *) alloca ((max_qty - max_reg) * sizeof (enum machine_mode));
8249 qty_const = (rtx *) alloca ((max_qty - max_reg) * sizeof (rtx));
8250 qty_const_insn = (rtx *) alloca ((max_qty - max_reg) * sizeof (rtx));
8252 = (enum rtx_code *) alloca ((max_qty - max_reg) * sizeof (enum rtx_code));
8253 qty_comparison_qty = (int *) alloca ((max_qty - max_reg) * sizeof (int));
8254 qty_comparison_const = (rtx *) alloca ((max_qty - max_reg) * sizeof (rtx));
8256 qty_first_reg -= max_reg;
8257 qty_last_reg -= max_reg;
8258 qty_mode -= max_reg;
8259 qty_const -= max_reg;
8260 qty_const_insn -= max_reg;
8261 qty_comparison_code -= max_reg;
8262 qty_comparison_qty -= max_reg;
8263 qty_comparison_const -= max_reg;
8267 /* TO might be a label. If so, protect it from being deleted. */
8268 if (to != 0 && GET_CODE (to) == CODE_LABEL)
8271 for (insn = from; insn != to; insn = NEXT_INSN (insn))
8273 register enum rtx_code code;
8275 /* See if this is a branch that is part of the path. If so, and it is
8276 to be taken, do so. */
8277 if (next_branch->branch == insn)
8279 enum taken status = next_branch++->status;
8280 if (status != NOT_TAKEN)
8282 if (status == TAKEN)
8283 record_jump_equiv (insn, 1);
8285 invalidate_skipped_block (NEXT_INSN (insn));
8287 /* Set the last insn as the jump insn; it doesn't affect cc0.
8288 Then follow this branch. */
8293 insn = JUMP_LABEL (insn);
8298 code = GET_CODE (insn);
8299 if (GET_MODE (insn) == QImode)
8300 PUT_MODE (insn, VOIDmode);
8302 if (GET_RTX_CLASS (code) == 'i')
8304 /* Process notes first so we have all notes in canonical forms when
8305 looking for duplicate operations. */
8307 if (REG_NOTES (insn))
8308 REG_NOTES (insn) = cse_process_notes (REG_NOTES (insn), NULL_RTX);
8310 /* Track when we are inside in LIBCALL block. Inside such a block,
8311 we do not want to record destinations. The last insn of a
8312 LIBCALL block is not considered to be part of the block, since
8313 its destination is the result of the block and hence should be
8316 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
8317 in_libcall_block = 1;
8318 else if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
8319 in_libcall_block = 0;
8321 cse_insn (insn, in_libcall_block);
8324 /* If INSN is now an unconditional jump, skip to the end of our
8325 basic block by pretending that we just did the last insn in the
8326 basic block. If we are jumping to the end of our block, show
8327 that we can have one usage of TO. */
8329 if (simplejump_p (insn))
8334 if (JUMP_LABEL (insn) == to)
8337 /* Maybe TO was deleted because the jump is unconditional.
8338 If so, there is nothing left in this basic block. */
8339 /* ??? Perhaps it would be smarter to set TO
8340 to whatever follows this insn,
8341 and pretend the basic block had always ended here. */
8342 if (INSN_DELETED_P (to))
8345 insn = PREV_INSN (to);
8348 /* See if it is ok to keep on going past the label
8349 which used to end our basic block. Remember that we incremented
8350 the count of that label, so we decrement it here. If we made
8351 a jump unconditional, TO_USAGE will be one; in that case, we don't
8352 want to count the use in that jump. */
8354 if (to != 0 && NEXT_INSN (insn) == to
8355 && GET_CODE (to) == CODE_LABEL && --LABEL_NUSES (to) == to_usage)
8357 struct cse_basic_block_data val;
8359 insn = NEXT_INSN (to);
8361 if (LABEL_NUSES (to) == 0)
8364 /* Find the end of the following block. Note that we won't be
8365 following branches in this case. If TO was the last insn
8366 in the function, we are done. Similarly, if we deleted the
8367 insn after TO, it must have been because it was preceded by
8368 a BARRIER. In that case, we are done with this block because it
8369 has no continuation. */
8371 if (insn == 0 || INSN_DELETED_P (insn))
8376 cse_end_of_basic_block (insn, &val, 0, 0, 0);
8378 /* If the tables we allocated have enough space left
8379 to handle all the SETs in the next basic block,
8380 continue through it. Otherwise, return,
8381 and that block will be scanned individually. */
8382 if (val.nsets * 2 + next_qty > max_qty)
8385 cse_basic_block_start = val.low_cuid;
8386 cse_basic_block_end = val.high_cuid;
8389 /* Prevent TO from being deleted if it is a label. */
8390 if (to != 0 && GET_CODE (to) == CODE_LABEL)
8393 /* Back up so we process the first insn in the extension. */
8394 insn = PREV_INSN (insn);
8398 if (next_qty > max_qty)
8401 /* If we are running before loop.c, we stopped on a NOTE_INSN_LOOP_END, and
8402 the previous insn is the only insn that branches to the head of a loop,
8403 we can cse into the loop. Don't do this if we changed the jump
8404 structure of a loop unless we aren't going to be following jumps. */
8406 if ((cse_jumps_altered == 0
8407 || (flag_cse_follow_jumps == 0 && flag_cse_skip_blocks == 0))
8408 && around_loop && to != 0
8409 && GET_CODE (to) == NOTE && NOTE_LINE_NUMBER (to) == NOTE_INSN_LOOP_END
8410 && GET_CODE (PREV_INSN (to)) == JUMP_INSN
8411 && JUMP_LABEL (PREV_INSN (to)) != 0
8412 && LABEL_NUSES (JUMP_LABEL (PREV_INSN (to))) == 1)
8413 cse_around_loop (JUMP_LABEL (PREV_INSN (to)));
8415 return to ? NEXT_INSN (to) : 0;
8418 /* Count the number of times registers are used (not set) in X.
8419 COUNTS is an array in which we accumulate the count, INCR is how much
8420 we count each register usage.
8422 Don't count a usage of DEST, which is the SET_DEST of a SET which
8423 contains X in its SET_SRC. This is because such a SET does not
8424 modify the liveness of DEST. */
8427 count_reg_usage (x, counts, dest, incr)
8440 switch (code = GET_CODE (x))
8444 counts[REGNO (x)] += incr;
8458 /* Unless we are setting a REG, count everything in SET_DEST. */
8459 if (GET_CODE (SET_DEST (x)) != REG)
8460 count_reg_usage (SET_DEST (x), counts, NULL_RTX, incr);
8462 /* If SRC has side-effects, then we can't delete this insn, so the
8463 usage of SET_DEST inside SRC counts.
8465 ??? Strictly-speaking, we might be preserving this insn
8466 because some other SET has side-effects, but that's hard
8467 to do and can't happen now. */
8468 count_reg_usage (SET_SRC (x), counts,
8469 side_effects_p (SET_SRC (x)) ? NULL_RTX : SET_DEST (x),
8474 count_reg_usage (CALL_INSN_FUNCTION_USAGE (x), counts, NULL_RTX, incr);
8476 /* ... falls through ... */
8479 count_reg_usage (PATTERN (x), counts, NULL_RTX, incr);
8481 /* Things used in a REG_EQUAL note aren't dead since loop may try to
8484 count_reg_usage (REG_NOTES (x), counts, NULL_RTX, incr);
8489 if (REG_NOTE_KIND (x) == REG_EQUAL
8490 || GET_CODE (XEXP (x,0)) == USE)
8491 count_reg_usage (XEXP (x, 0), counts, NULL_RTX, incr);
8492 count_reg_usage (XEXP (x, 1), counts, NULL_RTX, incr);
8496 fmt = GET_RTX_FORMAT (code);
8497 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
8500 count_reg_usage (XEXP (x, i), counts, dest, incr);
8501 else if (fmt[i] == 'E')
8502 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
8503 count_reg_usage (XVECEXP (x, i, j), counts, dest, incr);
8507 /* Scan all the insns and delete any that are dead; i.e., they store a register
8508 that is never used or they copy a register to itself.
8510 This is used to remove insns made obviously dead by cse. It improves the
8511 heuristics in loop since it won't try to move dead invariants out of loops
8512 or make givs for dead quantities. The remaining passes of the compilation
8513 are also sped up. */
8516 delete_dead_from_cse (insns, nreg)
8520 int *counts = (int *) alloca (nreg * sizeof (int));
8526 /* First count the number of times each register is used. */
8527 bzero ((char *) counts, sizeof (int) * nreg);
8528 for (insn = next_real_insn (insns); insn; insn = next_real_insn (insn))
8529 count_reg_usage (insn, counts, NULL_RTX, 1);
8531 /* Go from the last insn to the first and delete insns that only set unused
8532 registers or copy a register to itself. As we delete an insn, remove
8533 usage counts for registers it uses. */
8534 for (insn = prev_real_insn (get_last_insn ()); insn; insn = prev)
8538 prev = prev_real_insn (insn);
8540 /* Don't delete any insns that are part of a libcall block.
8541 Flow or loop might get confused if we did that. Remember
8542 that we are scanning backwards. */
8543 if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
8548 else if (GET_CODE (PATTERN (insn)) == SET)
8550 if (GET_CODE (SET_DEST (PATTERN (insn))) == REG
8551 && SET_DEST (PATTERN (insn)) == SET_SRC (PATTERN (insn)))
8555 else if (GET_CODE (SET_DEST (PATTERN (insn))) == CC0
8556 && ! side_effects_p (SET_SRC (PATTERN (insn)))
8557 && ((tem = next_nonnote_insn (insn)) == 0
8558 || GET_RTX_CLASS (GET_CODE (tem)) != 'i'
8559 || ! reg_referenced_p (cc0_rtx, PATTERN (tem))))
8562 else if (GET_CODE (SET_DEST (PATTERN (insn))) != REG
8563 || REGNO (SET_DEST (PATTERN (insn))) < FIRST_PSEUDO_REGISTER
8564 || counts[REGNO (SET_DEST (PATTERN (insn)))] != 0
8565 || side_effects_p (SET_SRC (PATTERN (insn))))
8568 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
8569 for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
8571 rtx elt = XVECEXP (PATTERN (insn), 0, i);
8573 if (GET_CODE (elt) == SET)
8575 if (GET_CODE (SET_DEST (elt)) == REG
8576 && SET_DEST (elt) == SET_SRC (elt))
8580 else if (GET_CODE (SET_DEST (elt)) == CC0
8581 && ! side_effects_p (SET_SRC (elt))
8582 && ((tem = next_nonnote_insn (insn)) == 0
8583 || GET_RTX_CLASS (GET_CODE (tem)) != 'i'
8584 || ! reg_referenced_p (cc0_rtx, PATTERN (tem))))
8587 else if (GET_CODE (SET_DEST (elt)) != REG
8588 || REGNO (SET_DEST (elt)) < FIRST_PSEUDO_REGISTER
8589 || counts[REGNO (SET_DEST (elt))] != 0
8590 || side_effects_p (SET_SRC (elt)))
8593 else if (GET_CODE (elt) != CLOBBER && GET_CODE (elt) != USE)
8599 /* If this is a dead insn, delete it and show registers in it aren't
8604 count_reg_usage (insn, counts, NULL_RTX, -1);
8608 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))