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));
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).
1484 A nonvarying address may be just a register or just
1485 a symbol reference, or it may be either of those plus
1486 a numeric offset. */
1493 register struct table_elt *p;
1495 HOST_WIDE_INT start, end;
1497 /* If X is a register, dependencies on its contents
1498 are recorded through the qty number mechanism.
1499 Just change the qty number of the register,
1500 mark it as invalid for expressions that refer to it,
1501 and remove it itself. */
1503 if (GET_CODE (x) == REG)
1505 register int regno = REGNO (x);
1506 register unsigned hash = HASH (x, GET_MODE (x));
1508 /* Remove REGNO from any quantity list it might be on and indicate
1509 that it's value might have changed. If it is a pseudo, remove its
1510 entry from the hash table.
1512 For a hard register, we do the first two actions above for any
1513 additional hard registers corresponding to X. Then, if any of these
1514 registers are in the table, we must remove any REG entries that
1515 overlap these registers. */
1517 delete_reg_equiv (regno);
1520 if (regno >= FIRST_PSEUDO_REGISTER)
1521 remove_from_table (lookup_for_remove (x, hash, GET_MODE (x)), hash);
1524 HOST_WIDE_INT in_table
1525 = TEST_HARD_REG_BIT (hard_regs_in_table, regno);
1526 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
1527 int tregno, tendregno;
1528 register struct table_elt *p, *next;
1530 CLEAR_HARD_REG_BIT (hard_regs_in_table, regno);
1532 for (i = regno + 1; i < endregno; i++)
1534 in_table |= TEST_HARD_REG_BIT (hard_regs_in_table, i);
1535 CLEAR_HARD_REG_BIT (hard_regs_in_table, i);
1536 delete_reg_equiv (i);
1541 for (hash = 0; hash < NBUCKETS; hash++)
1542 for (p = table[hash]; p; p = next)
1544 next = p->next_same_hash;
1546 if (GET_CODE (p->exp) != REG
1547 || REGNO (p->exp) >= FIRST_PSEUDO_REGISTER)
1550 tregno = REGNO (p->exp);
1552 = tregno + HARD_REGNO_NREGS (tregno, GET_MODE (p->exp));
1553 if (tendregno > regno && tregno < endregno)
1554 remove_from_table (p, hash);
1561 if (GET_CODE (x) == SUBREG)
1563 if (GET_CODE (SUBREG_REG (x)) != REG)
1565 invalidate (SUBREG_REG (x));
1569 /* X is not a register; it must be a memory reference with
1570 a nonvarying address. Remove all hash table elements
1571 that refer to overlapping pieces of memory. */
1573 if (GET_CODE (x) != MEM)
1576 set_nonvarying_address_components (XEXP (x, 0), GET_MODE_SIZE (GET_MODE (x)),
1577 &base, &start, &end);
1579 for (i = 0; i < NBUCKETS; i++)
1581 register struct table_elt *next;
1582 for (p = table[i]; p; p = next)
1584 next = p->next_same_hash;
1585 if (refers_to_mem_p (p->exp, base, start, end))
1586 remove_from_table (p, i);
1591 /* Remove all expressions that refer to register REGNO,
1592 since they are already invalid, and we are about to
1593 mark that register valid again and don't want the old
1594 expressions to reappear as valid. */
1597 remove_invalid_refs (regno)
1601 register struct table_elt *p, *next;
1603 for (i = 0; i < NBUCKETS; i++)
1604 for (p = table[i]; p; p = next)
1606 next = p->next_same_hash;
1607 if (GET_CODE (p->exp) != REG
1608 && refers_to_regno_p (regno, regno + 1, p->exp, NULL_PTR))
1609 remove_from_table (p, i);
1613 /* Recompute the hash codes of any valid entries in the hash table that
1614 reference X, if X is a register, or SUBREG_REG (X) if X is a SUBREG.
1616 This is called when we make a jump equivalence. */
1619 rehash_using_reg (x)
1623 struct table_elt *p, *next;
1626 if (GET_CODE (x) == SUBREG)
1629 /* If X is not a register or if the register is known not to be in any
1630 valid entries in the table, we have no work to do. */
1632 if (GET_CODE (x) != REG
1633 || reg_in_table[REGNO (x)] < 0
1634 || reg_in_table[REGNO (x)] != reg_tick[REGNO (x)])
1637 /* Scan all hash chains looking for valid entries that mention X.
1638 If we find one and it is in the wrong hash chain, move it. We can skip
1639 objects that are registers, since they are handled specially. */
1641 for (i = 0; i < NBUCKETS; i++)
1642 for (p = table[i]; p; p = next)
1644 next = p->next_same_hash;
1645 if (GET_CODE (p->exp) != REG && reg_mentioned_p (x, p->exp)
1646 && exp_equiv_p (p->exp, p->exp, 1, 0)
1647 && i != (hash = safe_hash (p->exp, p->mode) % NBUCKETS))
1649 if (p->next_same_hash)
1650 p->next_same_hash->prev_same_hash = p->prev_same_hash;
1652 if (p->prev_same_hash)
1653 p->prev_same_hash->next_same_hash = p->next_same_hash;
1655 table[i] = p->next_same_hash;
1657 p->next_same_hash = table[hash];
1658 p->prev_same_hash = 0;
1660 table[hash]->prev_same_hash = p;
1666 /* Remove from the hash table all expressions that reference memory,
1667 or some of them as specified by *WRITES. */
1670 invalidate_memory (writes)
1671 struct write_data *writes;
1674 register struct table_elt *p, *next;
1675 int all = writes->all;
1676 int nonscalar = writes->nonscalar;
1678 for (i = 0; i < NBUCKETS; i++)
1679 for (p = table[i]; p; p = next)
1681 next = p->next_same_hash;
1684 || (nonscalar && p->in_struct)
1685 || cse_rtx_addr_varies_p (p->exp)))
1686 remove_from_table (p, i);
1690 /* Remove from the hash table any expression that is a call-clobbered
1691 register. Also update their TICK values. */
1694 invalidate_for_call ()
1696 int regno, endregno;
1699 struct table_elt *p, *next;
1702 /* Go through all the hard registers. For each that is clobbered in
1703 a CALL_INSN, remove the register from quantity chains and update
1704 reg_tick if defined. Also see if any of these registers is currently
1707 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
1708 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
1710 delete_reg_equiv (regno);
1711 if (reg_tick[regno] >= 0)
1714 in_table |= TEST_HARD_REG_BIT (hard_regs_in_table, regno);
1717 /* In the case where we have no call-clobbered hard registers in the
1718 table, we are done. Otherwise, scan the table and remove any
1719 entry that overlaps a call-clobbered register. */
1722 for (hash = 0; hash < NBUCKETS; hash++)
1723 for (p = table[hash]; p; p = next)
1725 next = p->next_same_hash;
1727 if (GET_CODE (p->exp) != REG
1728 || REGNO (p->exp) >= FIRST_PSEUDO_REGISTER)
1731 regno = REGNO (p->exp);
1732 endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (p->exp));
1734 for (i = regno; i < endregno; i++)
1735 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1737 remove_from_table (p, hash);
1743 /* Given an expression X of type CONST,
1744 and ELT which is its table entry (or 0 if it
1745 is not in the hash table),
1746 return an alternate expression for X as a register plus integer.
1747 If none can be found, return 0. */
1750 use_related_value (x, elt)
1752 struct table_elt *elt;
1754 register struct table_elt *relt = 0;
1755 register struct table_elt *p, *q;
1756 HOST_WIDE_INT offset;
1758 /* First, is there anything related known?
1759 If we have a table element, we can tell from that.
1760 Otherwise, must look it up. */
1762 if (elt != 0 && elt->related_value != 0)
1764 else if (elt == 0 && GET_CODE (x) == CONST)
1766 rtx subexp = get_related_value (x);
1768 relt = lookup (subexp,
1769 safe_hash (subexp, GET_MODE (subexp)) % NBUCKETS,
1776 /* Search all related table entries for one that has an
1777 equivalent register. */
1782 /* This loop is strange in that it is executed in two different cases.
1783 The first is when X is already in the table. Then it is searching
1784 the RELATED_VALUE list of X's class (RELT). The second case is when
1785 X is not in the table. Then RELT points to a class for the related
1788 Ensure that, whatever case we are in, that we ignore classes that have
1789 the same value as X. */
1791 if (rtx_equal_p (x, p->exp))
1794 for (q = p->first_same_value; q; q = q->next_same_value)
1795 if (GET_CODE (q->exp) == REG)
1801 p = p->related_value;
1803 /* We went all the way around, so there is nothing to be found.
1804 Alternatively, perhaps RELT was in the table for some other reason
1805 and it has no related values recorded. */
1806 if (p == relt || p == 0)
1813 offset = (get_integer_term (x) - get_integer_term (p->exp));
1814 /* Note: OFFSET may be 0 if P->xexp and X are related by commutativity. */
1815 return plus_constant (q->exp, offset);
1818 /* Hash an rtx. We are careful to make sure the value is never negative.
1819 Equivalent registers hash identically.
1820 MODE is used in hashing for CONST_INTs only;
1821 otherwise the mode of X is used.
1823 Store 1 in do_not_record if any subexpression is volatile.
1825 Store 1 in hash_arg_in_memory if X contains a MEM rtx
1826 which does not have the RTX_UNCHANGING_P bit set.
1827 In this case, also store 1 in hash_arg_in_struct
1828 if there is a MEM rtx which has the MEM_IN_STRUCT_P bit set.
1830 Note that cse_insn knows that the hash code of a MEM expression
1831 is just (int) MEM plus the hash code of the address. */
1834 canon_hash (x, mode)
1836 enum machine_mode mode;
1839 register unsigned hash = 0;
1840 register enum rtx_code code;
1843 /* repeat is used to turn tail-recursion into iteration. */
1848 code = GET_CODE (x);
1853 register int regno = REGNO (x);
1855 /* On some machines, we can't record any non-fixed hard register,
1856 because extending its life will cause reload problems. We
1857 consider ap, fp, and sp to be fixed for this purpose.
1858 On all machines, we can't record any global registers. */
1860 if (regno < FIRST_PSEUDO_REGISTER
1861 && (global_regs[regno]
1862 #ifdef SMALL_REGISTER_CLASSES
1863 || (! fixed_regs[regno]
1864 && regno != FRAME_POINTER_REGNUM
1865 && regno != HARD_FRAME_POINTER_REGNUM
1866 && regno != ARG_POINTER_REGNUM
1867 && regno != STACK_POINTER_REGNUM)
1874 hash += ((unsigned) REG << 7) + (unsigned) reg_qty[regno];
1880 unsigned HOST_WIDE_INT tem = INTVAL (x);
1881 hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + tem;
1886 /* This is like the general case, except that it only counts
1887 the integers representing the constant. */
1888 hash += (unsigned) code + (unsigned) GET_MODE (x);
1889 for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
1891 unsigned tem = XINT (x, i);
1896 /* Assume there is only one rtx object for any given label. */
1899 += ((unsigned) LABEL_REF << 7) + (unsigned HOST_WIDE_INT) XEXP (x, 0);
1904 += ((unsigned) SYMBOL_REF << 7) + (unsigned HOST_WIDE_INT) XSTR (x, 0);
1908 if (MEM_VOLATILE_P (x))
1913 if (! RTX_UNCHANGING_P (x))
1915 hash_arg_in_memory = 1;
1916 if (MEM_IN_STRUCT_P (x)) hash_arg_in_struct = 1;
1918 /* Now that we have already found this special case,
1919 might as well speed it up as much as possible. */
1920 hash += (unsigned) MEM;
1931 case UNSPEC_VOLATILE:
1936 if (MEM_VOLATILE_P (x))
1943 i = GET_RTX_LENGTH (code) - 1;
1944 hash += (unsigned) code + (unsigned) GET_MODE (x);
1945 fmt = GET_RTX_FORMAT (code);
1950 rtx tem = XEXP (x, i);
1953 /* If the operand is a REG that is equivalent to a constant, hash
1954 as if we were hashing the constant, since we will be comparing
1956 if (tem != 0 && GET_CODE (tem) == REG
1957 && REGNO_QTY_VALID_P (REGNO (tem))
1958 && qty_mode[reg_qty[REGNO (tem)]] == GET_MODE (tem)
1959 && (tem1 = qty_const[reg_qty[REGNO (tem)]]) != 0
1960 && CONSTANT_P (tem1))
1963 /* If we are about to do the last recursive call
1964 needed at this level, change it into iteration.
1965 This function is called enough to be worth it. */
1971 hash += canon_hash (tem, 0);
1973 else if (fmt[i] == 'E')
1974 for (j = 0; j < XVECLEN (x, i); j++)
1975 hash += canon_hash (XVECEXP (x, i, j), 0);
1976 else if (fmt[i] == 's')
1978 register unsigned char *p = (unsigned char *) XSTR (x, i);
1983 else if (fmt[i] == 'i')
1985 register unsigned tem = XINT (x, i);
1994 /* Like canon_hash but with no side effects. */
1999 enum machine_mode mode;
2001 int save_do_not_record = do_not_record;
2002 int save_hash_arg_in_memory = hash_arg_in_memory;
2003 int save_hash_arg_in_struct = hash_arg_in_struct;
2004 unsigned hash = canon_hash (x, mode);
2005 hash_arg_in_memory = save_hash_arg_in_memory;
2006 hash_arg_in_struct = save_hash_arg_in_struct;
2007 do_not_record = save_do_not_record;
2011 /* Return 1 iff X and Y would canonicalize into the same thing,
2012 without actually constructing the canonicalization of either one.
2013 If VALIDATE is nonzero,
2014 we assume X is an expression being processed from the rtl
2015 and Y was found in the hash table. We check register refs
2016 in Y for being marked as valid.
2018 If EQUAL_VALUES is nonzero, we allow a register to match a constant value
2019 that is known to be in the register. Ordinarily, we don't allow them
2020 to match, because letting them match would cause unpredictable results
2021 in all the places that search a hash table chain for an equivalent
2022 for a given value. A possible equivalent that has different structure
2023 has its hash code computed from different data. Whether the hash code
2024 is the same as that of the the given value is pure luck. */
2027 exp_equiv_p (x, y, validate, equal_values)
2033 register enum rtx_code code;
2036 /* Note: it is incorrect to assume an expression is equivalent to itself
2037 if VALIDATE is nonzero. */
2038 if (x == y && !validate)
2040 if (x == 0 || y == 0)
2043 code = GET_CODE (x);
2044 if (code != GET_CODE (y))
2049 /* If X is a constant and Y is a register or vice versa, they may be
2050 equivalent. We only have to validate if Y is a register. */
2051 if (CONSTANT_P (x) && GET_CODE (y) == REG
2052 && REGNO_QTY_VALID_P (REGNO (y))
2053 && GET_MODE (y) == qty_mode[reg_qty[REGNO (y)]]
2054 && rtx_equal_p (x, qty_const[reg_qty[REGNO (y)]])
2055 && (! validate || reg_in_table[REGNO (y)] == reg_tick[REGNO (y)]))
2058 if (CONSTANT_P (y) && code == REG
2059 && REGNO_QTY_VALID_P (REGNO (x))
2060 && GET_MODE (x) == qty_mode[reg_qty[REGNO (x)]]
2061 && rtx_equal_p (y, qty_const[reg_qty[REGNO (x)]]))
2067 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
2068 if (GET_MODE (x) != GET_MODE (y))
2078 return INTVAL (x) == INTVAL (y);
2081 return XEXP (x, 0) == XEXP (y, 0);
2084 return XSTR (x, 0) == XSTR (y, 0);
2088 int regno = REGNO (y);
2090 = regno + (regno >= FIRST_PSEUDO_REGISTER ? 1
2091 : HARD_REGNO_NREGS (regno, GET_MODE (y)));
2094 /* If the quantities are not the same, the expressions are not
2095 equivalent. If there are and we are not to validate, they
2096 are equivalent. Otherwise, ensure all regs are up-to-date. */
2098 if (reg_qty[REGNO (x)] != reg_qty[regno])
2104 for (i = regno; i < endregno; i++)
2105 if (reg_in_table[i] != reg_tick[i])
2111 /* For commutative operations, check both orders. */
2119 return ((exp_equiv_p (XEXP (x, 0), XEXP (y, 0), validate, equal_values)
2120 && exp_equiv_p (XEXP (x, 1), XEXP (y, 1),
2121 validate, equal_values))
2122 || (exp_equiv_p (XEXP (x, 0), XEXP (y, 1),
2123 validate, equal_values)
2124 && exp_equiv_p (XEXP (x, 1), XEXP (y, 0),
2125 validate, equal_values)));
2128 /* Compare the elements. If any pair of corresponding elements
2129 fail to match, return 0 for the whole things. */
2131 fmt = GET_RTX_FORMAT (code);
2132 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2137 if (! exp_equiv_p (XEXP (x, i), XEXP (y, i), validate, equal_values))
2142 if (XVECLEN (x, i) != XVECLEN (y, i))
2144 for (j = 0; j < XVECLEN (x, i); j++)
2145 if (! exp_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j),
2146 validate, equal_values))
2151 if (strcmp (XSTR (x, i), XSTR (y, i)))
2156 if (XINT (x, i) != XINT (y, i))
2161 if (XWINT (x, i) != XWINT (y, i))
2176 /* Return 1 iff any subexpression of X matches Y.
2177 Here we do not require that X or Y be valid (for registers referred to)
2178 for being in the hash table. */
2185 register enum rtx_code code;
2191 if (x == 0 || y == 0)
2194 code = GET_CODE (x);
2195 /* If X as a whole has the same code as Y, they may match.
2197 if (code == GET_CODE (y))
2199 if (exp_equiv_p (x, y, 0, 1))
2203 /* X does not match, so try its subexpressions. */
2205 fmt = GET_RTX_FORMAT (code);
2206 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2215 if (refers_to_p (XEXP (x, i), y))
2218 else if (fmt[i] == 'E')
2221 for (j = 0; j < XVECLEN (x, i); j++)
2222 if (refers_to_p (XVECEXP (x, i, j), y))
2229 /* Given ADDR and SIZE (a memory address, and the size of the memory reference),
2230 set PBASE, PSTART, and PEND which correspond to the base of the address,
2231 the starting offset, and ending offset respectively.
2233 ADDR is known to be a nonvarying address.
2235 cse_address_varies_p returns zero for nonvarying addresses. */
2238 set_nonvarying_address_components (addr, size, pbase, pstart, pend)
2242 HOST_WIDE_INT *pstart, *pend;
2245 HOST_WIDE_INT start, end;
2251 /* Registers with nonvarying addresses usually have constant equivalents;
2252 but the frame pointer register is also possible. */
2253 if (GET_CODE (base) == REG
2255 && REGNO_QTY_VALID_P (REGNO (base))
2256 && qty_mode[reg_qty[REGNO (base)]] == GET_MODE (base)
2257 && qty_const[reg_qty[REGNO (base)]] != 0)
2258 base = qty_const[reg_qty[REGNO (base)]];
2259 else if (GET_CODE (base) == PLUS
2260 && GET_CODE (XEXP (base, 1)) == CONST_INT
2261 && GET_CODE (XEXP (base, 0)) == REG
2263 && REGNO_QTY_VALID_P (REGNO (XEXP (base, 0)))
2264 && (qty_mode[reg_qty[REGNO (XEXP (base, 0))]]
2265 == GET_MODE (XEXP (base, 0)))
2266 && qty_const[reg_qty[REGNO (XEXP (base, 0))]])
2268 start = INTVAL (XEXP (base, 1));
2269 base = qty_const[reg_qty[REGNO (XEXP (base, 0))]];
2272 /* Handle everything that we can find inside an address that has been
2273 viewed as constant. */
2277 /* If no part of this switch does a "continue", the code outside
2278 will exit this loop. */
2280 switch (GET_CODE (base))
2283 /* By definition, operand1 of a LO_SUM is the associated constant
2284 address. Use the associated constant address as the base
2286 base = XEXP (base, 1);
2290 /* Strip off CONST. */
2291 base = XEXP (base, 0);
2295 if (GET_CODE (XEXP (base, 1)) == CONST_INT)
2297 start += INTVAL (XEXP (base, 1));
2298 base = XEXP (base, 0);
2304 /* Handle the case of an AND which is the negative of a power of
2305 two. This is used to represent unaligned memory operations. */
2306 if (GET_CODE (XEXP (base, 1)) == CONST_INT
2307 && exact_log2 (- INTVAL (XEXP (base, 1))) > 0)
2309 set_nonvarying_address_components (XEXP (base, 0), size,
2310 pbase, pstart, pend);
2312 /* Assume the worst misalignment. START is affected, but not
2313 END, so compensate but adjusting SIZE. Don't lose any
2314 constant we already had. */
2316 size = *pend - *pstart - INTVAL (XEXP (base, 1)) - 1;
2317 start += *pstart - INTVAL (XEXP (base, 1)) - 1;
2328 /* Set the return values. */
2334 /* Return 1 iff any subexpression of X refers to memory
2335 at an address of BASE plus some offset
2336 such that any of the bytes' offsets fall between START (inclusive)
2337 and END (exclusive).
2339 The value is undefined if X is a varying address (as determined by
2340 cse_rtx_addr_varies_p). This function is not used in such cases.
2342 When used in the cse pass, `qty_const' is nonzero, and it is used
2343 to treat an address that is a register with a known constant value
2344 as if it were that constant value.
2345 In the loop pass, `qty_const' is zero, so this is not done. */
2348 refers_to_mem_p (x, base, start, end)
2350 HOST_WIDE_INT start, end;
2352 register HOST_WIDE_INT i;
2353 register enum rtx_code code;
2356 if (GET_CODE (base) == CONST_INT)
2358 start += INTVAL (base);
2359 end += INTVAL (base);
2367 code = GET_CODE (x);
2370 register rtx addr = XEXP (x, 0); /* Get the address. */
2372 HOST_WIDE_INT mystart, myend;
2374 set_nonvarying_address_components (addr, GET_MODE_SIZE (GET_MODE (x)),
2375 &mybase, &mystart, &myend);
2378 /* refers_to_mem_p is never called with varying addresses.
2379 If the base addresses are not equal, there is no chance
2380 of the memory addresses conflicting. */
2381 if (! rtx_equal_p (mybase, base))
2384 return myend > start && mystart < end;
2387 /* X does not match, so try its subexpressions. */
2389 fmt = GET_RTX_FORMAT (code);
2390 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2399 if (refers_to_mem_p (XEXP (x, i), base, start, end))
2402 else if (fmt[i] == 'E')
2405 for (j = 0; j < XVECLEN (x, i); j++)
2406 if (refers_to_mem_p (XVECEXP (x, i, j), base, start, end))
2413 /* Nonzero if X refers to memory at a varying address;
2414 except that a register which has at the moment a known constant value
2415 isn't considered variable. */
2418 cse_rtx_addr_varies_p (x)
2421 /* We need not check for X and the equivalence class being of the same
2422 mode because if X is equivalent to a constant in some mode, it
2423 doesn't vary in any mode. */
2425 if (GET_CODE (x) == MEM
2426 && GET_CODE (XEXP (x, 0)) == REG
2427 && REGNO_QTY_VALID_P (REGNO (XEXP (x, 0)))
2428 && GET_MODE (XEXP (x, 0)) == qty_mode[reg_qty[REGNO (XEXP (x, 0))]]
2429 && qty_const[reg_qty[REGNO (XEXP (x, 0))]] != 0)
2432 if (GET_CODE (x) == MEM
2433 && GET_CODE (XEXP (x, 0)) == PLUS
2434 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2435 && GET_CODE (XEXP (XEXP (x, 0), 0)) == REG
2436 && REGNO_QTY_VALID_P (REGNO (XEXP (XEXP (x, 0), 0)))
2437 && (GET_MODE (XEXP (XEXP (x, 0), 0))
2438 == qty_mode[reg_qty[REGNO (XEXP (XEXP (x, 0), 0))]])
2439 && qty_const[reg_qty[REGNO (XEXP (XEXP (x, 0), 0))]])
2442 return rtx_addr_varies_p (x);
2445 /* Canonicalize an expression:
2446 replace each register reference inside it
2447 with the "oldest" equivalent register.
2449 If INSN is non-zero and we are replacing a pseudo with a hard register
2450 or vice versa, validate_change is used to ensure that INSN remains valid
2451 after we make our substitution. The calls are made with IN_GROUP non-zero
2452 so apply_change_group must be called upon the outermost return from this
2453 function (unless INSN is zero). The result of apply_change_group can
2454 generally be discarded since the changes we are making are optional. */
2462 register enum rtx_code code;
2468 code = GET_CODE (x);
2486 /* Never replace a hard reg, because hard regs can appear
2487 in more than one machine mode, and we must preserve the mode
2488 of each occurrence. Also, some hard regs appear in
2489 MEMs that are shared and mustn't be altered. Don't try to
2490 replace any reg that maps to a reg of class NO_REGS. */
2491 if (REGNO (x) < FIRST_PSEUDO_REGISTER
2492 || ! REGNO_QTY_VALID_P (REGNO (x)))
2495 first = qty_first_reg[reg_qty[REGNO (x)]];
2496 return (first >= FIRST_PSEUDO_REGISTER ? regno_reg_rtx[first]
2497 : REGNO_REG_CLASS (first) == NO_REGS ? x
2498 : gen_rtx (REG, qty_mode[reg_qty[REGNO (x)]], first));
2502 fmt = GET_RTX_FORMAT (code);
2503 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2509 rtx new = canon_reg (XEXP (x, i), insn);
2511 /* If replacing pseudo with hard reg or vice versa, ensure the
2512 insn remains valid. Likewise if the insn has MATCH_DUPs. */
2513 if (insn != 0 && new != 0
2514 && GET_CODE (new) == REG && GET_CODE (XEXP (x, i)) == REG
2515 && (((REGNO (new) < FIRST_PSEUDO_REGISTER)
2516 != (REGNO (XEXP (x, i)) < FIRST_PSEUDO_REGISTER))
2517 || insn_n_dups[recog_memoized (insn)] > 0))
2518 validate_change (insn, &XEXP (x, i), new, 1);
2522 else if (fmt[i] == 'E')
2523 for (j = 0; j < XVECLEN (x, i); j++)
2524 XVECEXP (x, i, j) = canon_reg (XVECEXP (x, i, j), insn);
2530 /* LOC is a location with INSN that is an operand address (the contents of
2531 a MEM). Find the best equivalent address to use that is valid for this
2534 On most CISC machines, complicated address modes are costly, and rtx_cost
2535 is a good approximation for that cost. However, most RISC machines have
2536 only a few (usually only one) memory reference formats. If an address is
2537 valid at all, it is often just as cheap as any other address. Hence, for
2538 RISC machines, we use the configuration macro `ADDRESS_COST' to compare the
2539 costs of various addresses. For two addresses of equal cost, choose the one
2540 with the highest `rtx_cost' value as that has the potential of eliminating
2541 the most insns. For equal costs, we choose the first in the equivalence
2542 class. Note that we ignore the fact that pseudo registers are cheaper
2543 than hard registers here because we would also prefer the pseudo registers.
2547 find_best_addr (insn, loc)
2551 struct table_elt *elt, *p;
2554 int found_better = 1;
2555 int save_do_not_record = do_not_record;
2556 int save_hash_arg_in_memory = hash_arg_in_memory;
2557 int save_hash_arg_in_struct = hash_arg_in_struct;
2562 /* Do not try to replace constant addresses or addresses of local and
2563 argument slots. These MEM expressions are made only once and inserted
2564 in many instructions, as well as being used to control symbol table
2565 output. It is not safe to clobber them.
2567 There are some uncommon cases where the address is already in a register
2568 for some reason, but we cannot take advantage of that because we have
2569 no easy way to unshare the MEM. In addition, looking up all stack
2570 addresses is costly. */
2571 if ((GET_CODE (addr) == PLUS
2572 && GET_CODE (XEXP (addr, 0)) == REG
2573 && GET_CODE (XEXP (addr, 1)) == CONST_INT
2574 && (regno = REGNO (XEXP (addr, 0)),
2575 regno == FRAME_POINTER_REGNUM || regno == HARD_FRAME_POINTER_REGNUM
2576 || regno == ARG_POINTER_REGNUM))
2577 || (GET_CODE (addr) == REG
2578 && (regno = REGNO (addr), regno == FRAME_POINTER_REGNUM
2579 || regno == HARD_FRAME_POINTER_REGNUM
2580 || regno == ARG_POINTER_REGNUM))
2581 || CONSTANT_ADDRESS_P (addr))
2584 /* If this address is not simply a register, try to fold it. This will
2585 sometimes simplify the expression. Many simplifications
2586 will not be valid, but some, usually applying the associative rule, will
2587 be valid and produce better code. */
2588 if (GET_CODE (addr) != REG
2589 && validate_change (insn, loc, fold_rtx (addr, insn), 0))
2592 /* If this address is not in the hash table, we can't look for equivalences
2593 of the whole address. Also, ignore if volatile. */
2596 hash = HASH (addr, Pmode);
2597 addr_volatile = do_not_record;
2598 do_not_record = save_do_not_record;
2599 hash_arg_in_memory = save_hash_arg_in_memory;
2600 hash_arg_in_struct = save_hash_arg_in_struct;
2605 elt = lookup (addr, hash, Pmode);
2607 #ifndef ADDRESS_COST
2610 our_cost = elt->cost;
2612 /* Find the lowest cost below ours that works. */
2613 for (elt = elt->first_same_value; elt; elt = elt->next_same_value)
2614 if (elt->cost < our_cost
2615 && (GET_CODE (elt->exp) == REG
2616 || exp_equiv_p (elt->exp, elt->exp, 1, 0))
2617 && validate_change (insn, loc,
2618 canon_reg (copy_rtx (elt->exp), NULL_RTX), 0))
2625 /* We need to find the best (under the criteria documented above) entry
2626 in the class that is valid. We use the `flag' field to indicate
2627 choices that were invalid and iterate until we can't find a better
2628 one that hasn't already been tried. */
2630 for (p = elt->first_same_value; p; p = p->next_same_value)
2633 while (found_better)
2635 int best_addr_cost = ADDRESS_COST (*loc);
2636 int best_rtx_cost = (elt->cost + 1) >> 1;
2637 struct table_elt *best_elt = elt;
2640 for (p = elt->first_same_value; p; p = p->next_same_value)
2642 && (GET_CODE (p->exp) == REG
2643 || exp_equiv_p (p->exp, p->exp, 1, 0))
2644 && (ADDRESS_COST (p->exp) < best_addr_cost
2645 || (ADDRESS_COST (p->exp) == best_addr_cost
2646 && (p->cost + 1) >> 1 > best_rtx_cost)))
2649 best_addr_cost = ADDRESS_COST (p->exp);
2650 best_rtx_cost = (p->cost + 1) >> 1;
2656 if (validate_change (insn, loc,
2657 canon_reg (copy_rtx (best_elt->exp),
2666 /* If the address is a binary operation with the first operand a register
2667 and the second a constant, do the same as above, but looking for
2668 equivalences of the register. Then try to simplify before checking for
2669 the best address to use. This catches a few cases: First is when we
2670 have REG+const and the register is another REG+const. We can often merge
2671 the constants and eliminate one insn and one register. It may also be
2672 that a machine has a cheap REG+REG+const. Finally, this improves the
2673 code on the Alpha for unaligned byte stores. */
2675 if (flag_expensive_optimizations
2676 && (GET_RTX_CLASS (GET_CODE (*loc)) == '2'
2677 || GET_RTX_CLASS (GET_CODE (*loc)) == 'c')
2678 && GET_CODE (XEXP (*loc, 0)) == REG
2679 && GET_CODE (XEXP (*loc, 1)) == CONST_INT)
2681 rtx c = XEXP (*loc, 1);
2684 hash = HASH (XEXP (*loc, 0), Pmode);
2685 do_not_record = save_do_not_record;
2686 hash_arg_in_memory = save_hash_arg_in_memory;
2687 hash_arg_in_struct = save_hash_arg_in_struct;
2689 elt = lookup (XEXP (*loc, 0), hash, Pmode);
2693 /* We need to find the best (under the criteria documented above) entry
2694 in the class that is valid. We use the `flag' field to indicate
2695 choices that were invalid and iterate until we can't find a better
2696 one that hasn't already been tried. */
2698 for (p = elt->first_same_value; p; p = p->next_same_value)
2701 while (found_better)
2703 int best_addr_cost = ADDRESS_COST (*loc);
2704 int best_rtx_cost = (COST (*loc) + 1) >> 1;
2705 struct table_elt *best_elt = elt;
2706 rtx best_rtx = *loc;
2709 /* This is at worst case an O(n^2) algorithm, so limit our search
2710 to the first 32 elements on the list. This avoids trouble
2711 compiling code with very long basic blocks that can easily
2712 call cse_gen_binary so many times that we run out of memory. */
2715 for (p = elt->first_same_value, count = 0;
2717 p = p->next_same_value, count++)
2719 && (GET_CODE (p->exp) == REG
2720 || exp_equiv_p (p->exp, p->exp, 1, 0)))
2722 rtx new = cse_gen_binary (GET_CODE (*loc), Pmode, p->exp, c);
2724 if ((ADDRESS_COST (new) < best_addr_cost
2725 || (ADDRESS_COST (new) == best_addr_cost
2726 && (COST (new) + 1) >> 1 > best_rtx_cost)))
2729 best_addr_cost = ADDRESS_COST (new);
2730 best_rtx_cost = (COST (new) + 1) >> 1;
2738 if (validate_change (insn, loc,
2739 canon_reg (copy_rtx (best_rtx),
2750 /* Given an operation (CODE, *PARG1, *PARG2), where code is a comparison
2751 operation (EQ, NE, GT, etc.), follow it back through the hash table and
2752 what values are being compared.
2754 *PARG1 and *PARG2 are updated to contain the rtx representing the values
2755 actually being compared. For example, if *PARG1 was (cc0) and *PARG2
2756 was (const_int 0), *PARG1 and *PARG2 will be set to the objects that were
2757 compared to produce cc0.
2759 The return value is the comparison operator and is either the code of
2760 A or the code corresponding to the inverse of the comparison. */
2762 static enum rtx_code
2763 find_comparison_args (code, parg1, parg2, pmode1, pmode2)
2766 enum machine_mode *pmode1, *pmode2;
2770 arg1 = *parg1, arg2 = *parg2;
2772 /* If ARG2 is const0_rtx, see what ARG1 is equivalent to. */
2774 while (arg2 == CONST0_RTX (GET_MODE (arg1)))
2776 /* Set non-zero when we find something of interest. */
2778 int reverse_code = 0;
2779 struct table_elt *p = 0;
2781 /* If arg1 is a COMPARE, extract the comparison arguments from it.
2782 On machines with CC0, this is the only case that can occur, since
2783 fold_rtx will return the COMPARE or item being compared with zero
2786 if (GET_CODE (arg1) == COMPARE && arg2 == const0_rtx)
2789 /* If ARG1 is a comparison operator and CODE is testing for
2790 STORE_FLAG_VALUE, get the inner arguments. */
2792 else if (GET_RTX_CLASS (GET_CODE (arg1)) == '<')
2795 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_INT
2796 && code == LT && STORE_FLAG_VALUE == -1)
2797 #ifdef FLOAT_STORE_FLAG_VALUE
2798 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_FLOAT
2799 && FLOAT_STORE_FLAG_VALUE < 0)
2804 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_INT
2805 && code == GE && STORE_FLAG_VALUE == -1)
2806 #ifdef FLOAT_STORE_FLAG_VALUE
2807 || (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_FLOAT
2808 && FLOAT_STORE_FLAG_VALUE < 0)
2811 x = arg1, reverse_code = 1;
2814 /* ??? We could also check for
2816 (ne (and (eq (...) (const_int 1))) (const_int 0))
2818 and related forms, but let's wait until we see them occurring. */
2821 /* Look up ARG1 in the hash table and see if it has an equivalence
2822 that lets us see what is being compared. */
2823 p = lookup (arg1, safe_hash (arg1, GET_MODE (arg1)) % NBUCKETS,
2825 if (p) p = p->first_same_value;
2827 for (; p; p = p->next_same_value)
2829 enum machine_mode inner_mode = GET_MODE (p->exp);
2831 /* If the entry isn't valid, skip it. */
2832 if (! exp_equiv_p (p->exp, p->exp, 1, 0))
2835 if (GET_CODE (p->exp) == COMPARE
2836 /* Another possibility is that this machine has a compare insn
2837 that includes the comparison code. In that case, ARG1 would
2838 be equivalent to a comparison operation that would set ARG1 to
2839 either STORE_FLAG_VALUE or zero. If this is an NE operation,
2840 ORIG_CODE is the actual comparison being done; if it is an EQ,
2841 we must reverse ORIG_CODE. On machine with a negative value
2842 for STORE_FLAG_VALUE, also look at LT and GE operations. */
2845 && GET_MODE_CLASS (inner_mode) == MODE_INT
2846 && (GET_MODE_BITSIZE (inner_mode)
2847 <= HOST_BITS_PER_WIDE_INT)
2848 && (STORE_FLAG_VALUE
2849 & ((HOST_WIDE_INT) 1
2850 << (GET_MODE_BITSIZE (inner_mode) - 1))))
2851 #ifdef FLOAT_STORE_FLAG_VALUE
2853 && GET_MODE_CLASS (inner_mode) == MODE_FLOAT
2854 && FLOAT_STORE_FLAG_VALUE < 0)
2857 && GET_RTX_CLASS (GET_CODE (p->exp)) == '<'))
2862 else if ((code == EQ
2864 && GET_MODE_CLASS (inner_mode) == MODE_INT
2865 && (GET_MODE_BITSIZE (inner_mode)
2866 <= HOST_BITS_PER_WIDE_INT)
2867 && (STORE_FLAG_VALUE
2868 & ((HOST_WIDE_INT) 1
2869 << (GET_MODE_BITSIZE (inner_mode) - 1))))
2870 #ifdef FLOAT_STORE_FLAG_VALUE
2872 && GET_MODE_CLASS (inner_mode) == MODE_FLOAT
2873 && FLOAT_STORE_FLAG_VALUE < 0)
2876 && GET_RTX_CLASS (GET_CODE (p->exp)) == '<')
2883 /* If this is fp + constant, the equivalent is a better operand since
2884 it may let us predict the value of the comparison. */
2885 else if (NONZERO_BASE_PLUS_P (p->exp))
2892 /* If we didn't find a useful equivalence for ARG1, we are done.
2893 Otherwise, set up for the next iteration. */
2897 arg1 = XEXP (x, 0), arg2 = XEXP (x, 1);
2898 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
2899 code = GET_CODE (x);
2902 code = reverse_condition (code);
2905 /* Return our results. Return the modes from before fold_rtx
2906 because fold_rtx might produce const_int, and then it's too late. */
2907 *pmode1 = GET_MODE (arg1), *pmode2 = GET_MODE (arg2);
2908 *parg1 = fold_rtx (arg1, 0), *parg2 = fold_rtx (arg2, 0);
2913 /* Try to simplify a unary operation CODE whose output mode is to be
2914 MODE with input operand OP whose mode was originally OP_MODE.
2915 Return zero if no simplification can be made. */
2918 simplify_unary_operation (code, mode, op, op_mode)
2920 enum machine_mode mode;
2922 enum machine_mode op_mode;
2924 register int width = GET_MODE_BITSIZE (mode);
2926 /* The order of these tests is critical so that, for example, we don't
2927 check the wrong mode (input vs. output) for a conversion operation,
2928 such as FIX. At some point, this should be simplified. */
2930 #if !defined(REAL_IS_NOT_DOUBLE) || defined(REAL_ARITHMETIC)
2932 if (code == FLOAT && GET_MODE (op) == VOIDmode
2933 && (GET_CODE (op) == CONST_DOUBLE || GET_CODE (op) == CONST_INT))
2935 HOST_WIDE_INT hv, lv;
2938 if (GET_CODE (op) == CONST_INT)
2939 lv = INTVAL (op), hv = INTVAL (op) < 0 ? -1 : 0;
2941 lv = CONST_DOUBLE_LOW (op), hv = CONST_DOUBLE_HIGH (op);
2943 #ifdef REAL_ARITHMETIC
2944 REAL_VALUE_FROM_INT (d, lv, hv);
2948 d = (double) (~ hv);
2949 d *= ((double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2))
2950 * (double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)));
2951 d += (double) (unsigned HOST_WIDE_INT) (~ lv);
2957 d *= ((double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2))
2958 * (double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)));
2959 d += (double) (unsigned HOST_WIDE_INT) lv;
2961 #endif /* REAL_ARITHMETIC */
2963 return CONST_DOUBLE_FROM_REAL_VALUE (d, mode);
2965 else if (code == UNSIGNED_FLOAT && GET_MODE (op) == VOIDmode
2966 && (GET_CODE (op) == CONST_DOUBLE || GET_CODE (op) == CONST_INT))
2968 HOST_WIDE_INT hv, lv;
2971 if (GET_CODE (op) == CONST_INT)
2972 lv = INTVAL (op), hv = INTVAL (op) < 0 ? -1 : 0;
2974 lv = CONST_DOUBLE_LOW (op), hv = CONST_DOUBLE_HIGH (op);
2976 if (GET_MODE_BITSIZE (op_mode) >= HOST_BITS_PER_WIDE_INT * 2)
2979 hv = 0, lv &= GET_MODE_MASK (op_mode);
2981 #ifdef REAL_ARITHMETIC
2982 REAL_VALUE_FROM_UNSIGNED_INT (d, lv, hv);
2985 d = (double) (unsigned HOST_WIDE_INT) hv;
2986 d *= ((double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2))
2987 * (double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)));
2988 d += (double) (unsigned HOST_WIDE_INT) lv;
2989 #endif /* REAL_ARITHMETIC */
2991 return CONST_DOUBLE_FROM_REAL_VALUE (d, mode);
2995 if (GET_CODE (op) == CONST_INT
2996 && width <= HOST_BITS_PER_WIDE_INT && width > 0)
2998 register HOST_WIDE_INT arg0 = INTVAL (op);
2999 register HOST_WIDE_INT val;
3012 val = (arg0 >= 0 ? arg0 : - arg0);
3016 /* Don't use ffs here. Instead, get low order bit and then its
3017 number. If arg0 is zero, this will return 0, as desired. */
3018 arg0 &= GET_MODE_MASK (mode);
3019 val = exact_log2 (arg0 & (- arg0)) + 1;
3027 if (op_mode == VOIDmode)
3029 if (GET_MODE_BITSIZE (op_mode) == HOST_BITS_PER_WIDE_INT)
3031 /* If we were really extending the mode,
3032 we would have to distinguish between zero-extension
3033 and sign-extension. */
3034 if (width != GET_MODE_BITSIZE (op_mode))
3038 else if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT)
3039 val = arg0 & ~((HOST_WIDE_INT) (-1) << GET_MODE_BITSIZE (op_mode));
3045 if (op_mode == VOIDmode)
3047 if (GET_MODE_BITSIZE (op_mode) == HOST_BITS_PER_WIDE_INT)
3049 /* If we were really extending the mode,
3050 we would have to distinguish between zero-extension
3051 and sign-extension. */
3052 if (width != GET_MODE_BITSIZE (op_mode))
3056 else if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT)
3059 = arg0 & ~((HOST_WIDE_INT) (-1) << GET_MODE_BITSIZE (op_mode));
3061 & ((HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (op_mode) - 1)))
3062 val -= (HOST_WIDE_INT) 1 << GET_MODE_BITSIZE (op_mode);
3075 /* Clear the bits that don't belong in our mode,
3076 unless they and our sign bit are all one.
3077 So we get either a reasonable negative value or a reasonable
3078 unsigned value for this mode. */
3079 if (width < HOST_BITS_PER_WIDE_INT
3080 && ((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
3081 != ((HOST_WIDE_INT) (-1) << (width - 1))))
3082 val &= (1 << width) - 1;
3084 return GEN_INT (val);
3087 /* We can do some operations on integer CONST_DOUBLEs. Also allow
3088 for a DImode operation on a CONST_INT. */
3089 else if (GET_MODE (op) == VOIDmode && width == HOST_BITS_PER_INT * 2
3090 && (GET_CODE (op) == CONST_DOUBLE || GET_CODE (op) == CONST_INT))
3092 HOST_WIDE_INT l1, h1, lv, hv;
3094 if (GET_CODE (op) == CONST_DOUBLE)
3095 l1 = CONST_DOUBLE_LOW (op), h1 = CONST_DOUBLE_HIGH (op);
3097 l1 = INTVAL (op), h1 = l1 < 0 ? -1 : 0;
3107 neg_double (l1, h1, &lv, &hv);
3112 neg_double (l1, h1, &lv, &hv);
3120 lv = HOST_BITS_PER_WIDE_INT + exact_log2 (h1 & (-h1)) + 1;
3122 lv = exact_log2 (l1 & (-l1)) + 1;
3126 if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
3127 return GEN_INT (l1 & GET_MODE_MASK (mode));
3133 if (op_mode == VOIDmode
3134 || GET_MODE_BITSIZE (op_mode) > HOST_BITS_PER_WIDE_INT)
3138 lv = l1 & GET_MODE_MASK (op_mode);
3142 if (op_mode == VOIDmode
3143 || GET_MODE_BITSIZE (op_mode) > HOST_BITS_PER_WIDE_INT)
3147 lv = l1 & GET_MODE_MASK (op_mode);
3148 if (GET_MODE_BITSIZE (op_mode) < HOST_BITS_PER_WIDE_INT
3149 && (lv & ((HOST_WIDE_INT) 1
3150 << (GET_MODE_BITSIZE (op_mode) - 1))) != 0)
3151 lv -= (HOST_WIDE_INT) 1 << GET_MODE_BITSIZE (op_mode);
3153 hv = (lv < 0) ? ~ (HOST_WIDE_INT) 0 : 0;
3164 return immed_double_const (lv, hv, mode);
3167 #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
3168 else if (GET_CODE (op) == CONST_DOUBLE
3169 && GET_MODE_CLASS (mode) == MODE_FLOAT)
3175 if (setjmp (handler))
3176 /* There used to be a warning here, but that is inadvisable.
3177 People may want to cause traps, and the natural way
3178 to do it should not get a warning. */
3181 set_float_handler (handler);
3183 REAL_VALUE_FROM_CONST_DOUBLE (d, op);
3188 d = REAL_VALUE_NEGATE (d);
3192 if (REAL_VALUE_NEGATIVE (d))
3193 d = REAL_VALUE_NEGATE (d);
3196 case FLOAT_TRUNCATE:
3197 d = real_value_truncate (mode, d);
3201 /* All this does is change the mode. */
3205 d = REAL_VALUE_RNDZINT (d);
3209 d = REAL_VALUE_UNSIGNED_RNDZINT (d);
3219 x = CONST_DOUBLE_FROM_REAL_VALUE (d, mode);
3220 set_float_handler (NULL_PTR);
3223 else if (GET_CODE (op) == CONST_DOUBLE && GET_MODE_CLASS (mode) == MODE_INT
3224 && width <= HOST_BITS_PER_WIDE_INT && width > 0)
3230 if (setjmp (handler))
3233 set_float_handler (handler);
3235 REAL_VALUE_FROM_CONST_DOUBLE (d, op);
3240 val = REAL_VALUE_FIX (d);
3244 val = REAL_VALUE_UNSIGNED_FIX (d);
3251 set_float_handler (NULL_PTR);
3253 /* Clear the bits that don't belong in our mode,
3254 unless they and our sign bit are all one.
3255 So we get either a reasonable negative value or a reasonable
3256 unsigned value for this mode. */
3257 if (width < HOST_BITS_PER_WIDE_INT
3258 && ((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
3259 != ((HOST_WIDE_INT) (-1) << (width - 1))))
3260 val &= ((HOST_WIDE_INT) 1 << width) - 1;
3262 return GEN_INT (val);
3265 /* This was formerly used only for non-IEEE float.
3266 eggert@twinsun.com says it is safe for IEEE also. */
3269 /* There are some simplifications we can do even if the operands
3275 /* (not (not X)) == X, similarly for NEG. */
3276 if (GET_CODE (op) == code)
3277 return XEXP (op, 0);
3281 /* (sign_extend (truncate (minus (label_ref L1) (label_ref L2))))
3282 becomes just the MINUS if its mode is MODE. This allows
3283 folding switch statements on machines using casesi (such as
3285 if (GET_CODE (op) == TRUNCATE
3286 && GET_MODE (XEXP (op, 0)) == mode
3287 && GET_CODE (XEXP (op, 0)) == MINUS
3288 && GET_CODE (XEXP (XEXP (op, 0), 0)) == LABEL_REF
3289 && GET_CODE (XEXP (XEXP (op, 0), 1)) == LABEL_REF)
3290 return XEXP (op, 0);
3298 /* Simplify a binary operation CODE with result mode MODE, operating on OP0
3299 and OP1. Return 0 if no simplification is possible.
3301 Don't use this for relational operations such as EQ or LT.
3302 Use simplify_relational_operation instead. */
3305 simplify_binary_operation (code, mode, op0, op1)
3307 enum machine_mode mode;
3310 register HOST_WIDE_INT arg0, arg1, arg0s, arg1s;
3312 int width = GET_MODE_BITSIZE (mode);
3315 /* Relational operations don't work here. We must know the mode
3316 of the operands in order to do the comparison correctly.
3317 Assuming a full word can give incorrect results.
3318 Consider comparing 128 with -128 in QImode. */
3320 if (GET_RTX_CLASS (code) == '<')
3323 #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
3324 if (GET_MODE_CLASS (mode) == MODE_FLOAT
3325 && GET_CODE (op0) == CONST_DOUBLE && GET_CODE (op1) == CONST_DOUBLE
3326 && mode == GET_MODE (op0) && mode == GET_MODE (op1))
3328 REAL_VALUE_TYPE f0, f1, value;
3331 if (setjmp (handler))
3334 set_float_handler (handler);
3336 REAL_VALUE_FROM_CONST_DOUBLE (f0, op0);
3337 REAL_VALUE_FROM_CONST_DOUBLE (f1, op1);
3338 f0 = real_value_truncate (mode, f0);
3339 f1 = real_value_truncate (mode, f1);
3341 #ifdef REAL_ARITHMETIC
3342 REAL_ARITHMETIC (value, rtx_to_tree_code (code), f0, f1);
3356 #ifndef REAL_INFINITY
3363 value = MIN (f0, f1);
3366 value = MAX (f0, f1);
3373 value = real_value_truncate (mode, value);
3374 set_float_handler (NULL_PTR);
3375 return CONST_DOUBLE_FROM_REAL_VALUE (value, mode);
3377 #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
3379 /* We can fold some multi-word operations. */
3380 if (GET_MODE_CLASS (mode) == MODE_INT
3381 && width == HOST_BITS_PER_WIDE_INT * 2
3382 && (GET_CODE (op0) == CONST_DOUBLE || GET_CODE (op0) == CONST_INT)
3383 && (GET_CODE (op1) == CONST_DOUBLE || GET_CODE (op1) == CONST_INT))
3385 HOST_WIDE_INT l1, l2, h1, h2, lv, hv;
3387 if (GET_CODE (op0) == CONST_DOUBLE)
3388 l1 = CONST_DOUBLE_LOW (op0), h1 = CONST_DOUBLE_HIGH (op0);
3390 l1 = INTVAL (op0), h1 = l1 < 0 ? -1 : 0;
3392 if (GET_CODE (op1) == CONST_DOUBLE)
3393 l2 = CONST_DOUBLE_LOW (op1), h2 = CONST_DOUBLE_HIGH (op1);
3395 l2 = INTVAL (op1), h2 = l2 < 0 ? -1 : 0;
3400 /* A - B == A + (-B). */
3401 neg_double (l2, h2, &lv, &hv);
3404 /* .. fall through ... */
3407 add_double (l1, h1, l2, h2, &lv, &hv);
3411 mul_double (l1, h1, l2, h2, &lv, &hv);
3414 case DIV: case MOD: case UDIV: case UMOD:
3415 /* We'd need to include tree.h to do this and it doesn't seem worth
3420 lv = l1 & l2, hv = h1 & h2;
3424 lv = l1 | l2, hv = h1 | h2;
3428 lv = l1 ^ l2, hv = h1 ^ h2;
3434 && ((unsigned HOST_WIDE_INT) l1
3435 < (unsigned HOST_WIDE_INT) l2)))
3444 && ((unsigned HOST_WIDE_INT) l1
3445 > (unsigned HOST_WIDE_INT) l2)))
3452 if ((unsigned HOST_WIDE_INT) h1 < (unsigned HOST_WIDE_INT) h2
3454 && ((unsigned HOST_WIDE_INT) l1
3455 < (unsigned HOST_WIDE_INT) l2)))
3462 if ((unsigned HOST_WIDE_INT) h1 > (unsigned HOST_WIDE_INT) h2
3464 && ((unsigned HOST_WIDE_INT) l1
3465 > (unsigned HOST_WIDE_INT) l2)))
3471 case LSHIFTRT: case ASHIFTRT:
3473 case ROTATE: case ROTATERT:
3474 #ifdef SHIFT_COUNT_TRUNCATED
3475 if (SHIFT_COUNT_TRUNCATED)
3476 l2 &= (GET_MODE_BITSIZE (mode) - 1), h2 = 0;
3479 if (h2 != 0 || l2 < 0 || l2 >= GET_MODE_BITSIZE (mode))
3482 if (code == LSHIFTRT || code == ASHIFTRT)
3483 rshift_double (l1, h1, l2, GET_MODE_BITSIZE (mode), &lv, &hv,
3485 else if (code == ASHIFT)
3486 lshift_double (l1, h1, l2, GET_MODE_BITSIZE (mode), &lv, &hv, 1);
3487 else if (code == ROTATE)
3488 lrotate_double (l1, h1, l2, GET_MODE_BITSIZE (mode), &lv, &hv);
3489 else /* code == ROTATERT */
3490 rrotate_double (l1, h1, l2, GET_MODE_BITSIZE (mode), &lv, &hv);
3497 return immed_double_const (lv, hv, mode);
3500 if (GET_CODE (op0) != CONST_INT || GET_CODE (op1) != CONST_INT
3501 || width > HOST_BITS_PER_WIDE_INT || width == 0)
3503 /* Even if we can't compute a constant result,
3504 there are some cases worth simplifying. */
3509 /* In IEEE floating point, x+0 is not the same as x. Similarly
3510 for the other optimizations below. */
3511 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
3512 && FLOAT_MODE_P (mode) && ! flag_fast_math)
3515 if (op1 == CONST0_RTX (mode))
3518 /* ((-a) + b) -> (b - a) and similarly for (a + (-b)) */
3519 if (GET_CODE (op0) == NEG)
3520 return cse_gen_binary (MINUS, mode, op1, XEXP (op0, 0));
3521 else if (GET_CODE (op1) == NEG)
3522 return cse_gen_binary (MINUS, mode, op0, XEXP (op1, 0));
3524 /* Handle both-operands-constant cases. We can only add
3525 CONST_INTs to constants since the sum of relocatable symbols
3526 can't be handled by most assemblers. Don't add CONST_INT
3527 to CONST_INT since overflow won't be computed properly if wider
3528 than HOST_BITS_PER_WIDE_INT. */
3530 if (CONSTANT_P (op0) && GET_MODE (op0) != VOIDmode
3531 && GET_CODE (op1) == CONST_INT)
3532 return plus_constant (op0, INTVAL (op1));
3533 else if (CONSTANT_P (op1) && GET_MODE (op1) != VOIDmode
3534 && GET_CODE (op0) == CONST_INT)
3535 return plus_constant (op1, INTVAL (op0));
3537 /* See if this is something like X * C - X or vice versa or
3538 if the multiplication is written as a shift. If so, we can
3539 distribute and make a new multiply, shift, or maybe just
3540 have X (if C is 2 in the example above). But don't make
3541 real multiply if we didn't have one before. */
3543 if (! FLOAT_MODE_P (mode))
3545 HOST_WIDE_INT coeff0 = 1, coeff1 = 1;
3546 rtx lhs = op0, rhs = op1;
3549 if (GET_CODE (lhs) == NEG)
3550 coeff0 = -1, lhs = XEXP (lhs, 0);
3551 else if (GET_CODE (lhs) == MULT
3552 && GET_CODE (XEXP (lhs, 1)) == CONST_INT)
3554 coeff0 = INTVAL (XEXP (lhs, 1)), lhs = XEXP (lhs, 0);
3557 else if (GET_CODE (lhs) == ASHIFT
3558 && GET_CODE (XEXP (lhs, 1)) == CONST_INT
3559 && INTVAL (XEXP (lhs, 1)) >= 0
3560 && INTVAL (XEXP (lhs, 1)) < HOST_BITS_PER_WIDE_INT)
3562 coeff0 = ((HOST_WIDE_INT) 1) << INTVAL (XEXP (lhs, 1));
3563 lhs = XEXP (lhs, 0);
3566 if (GET_CODE (rhs) == NEG)
3567 coeff1 = -1, rhs = XEXP (rhs, 0);
3568 else if (GET_CODE (rhs) == MULT
3569 && GET_CODE (XEXP (rhs, 1)) == CONST_INT)
3571 coeff1 = INTVAL (XEXP (rhs, 1)), rhs = XEXP (rhs, 0);
3574 else if (GET_CODE (rhs) == ASHIFT
3575 && GET_CODE (XEXP (rhs, 1)) == CONST_INT
3576 && INTVAL (XEXP (rhs, 1)) >= 0
3577 && INTVAL (XEXP (rhs, 1)) < HOST_BITS_PER_WIDE_INT)
3579 coeff1 = ((HOST_WIDE_INT) 1) << INTVAL (XEXP (rhs, 1));
3580 rhs = XEXP (rhs, 0);
3583 if (rtx_equal_p (lhs, rhs))
3585 tem = cse_gen_binary (MULT, mode, lhs,
3586 GEN_INT (coeff0 + coeff1));
3587 return (GET_CODE (tem) == MULT && ! had_mult) ? 0 : tem;
3591 /* If one of the operands is a PLUS or a MINUS, see if we can
3592 simplify this by the associative law.
3593 Don't use the associative law for floating point.
3594 The inaccuracy makes it nonassociative,
3595 and subtle programs can break if operations are associated. */
3597 if (INTEGRAL_MODE_P (mode)
3598 && (GET_CODE (op0) == PLUS || GET_CODE (op0) == MINUS
3599 || GET_CODE (op1) == PLUS || GET_CODE (op1) == MINUS)
3600 && (tem = simplify_plus_minus (code, mode, op0, op1)) != 0)
3606 /* Convert (compare FOO (const_int 0)) to FOO unless we aren't
3607 using cc0, in which case we want to leave it as a COMPARE
3608 so we can distinguish it from a register-register-copy.
3610 In IEEE floating point, x-0 is not the same as x. */
3612 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3613 || ! FLOAT_MODE_P (mode) || flag_fast_math)
3614 && op1 == CONST0_RTX (mode))
3617 /* Do nothing here. */
3622 /* None of these optimizations can be done for IEEE
3624 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
3625 && FLOAT_MODE_P (mode) && ! flag_fast_math)
3628 /* We can't assume x-x is 0 even with non-IEEE floating point,
3629 but since it is zero except in very strange circumstances, we
3630 will treat it as zero with -ffast-math. */
3631 if (rtx_equal_p (op0, op1)
3632 && ! side_effects_p (op0)
3633 && (! FLOAT_MODE_P (mode) || flag_fast_math))
3634 return CONST0_RTX (mode);
3636 /* Change subtraction from zero into negation. */
3637 if (op0 == CONST0_RTX (mode))
3638 return gen_rtx (NEG, mode, op1);
3640 /* (-1 - a) is ~a. */
3641 if (op0 == constm1_rtx)
3642 return gen_rtx (NOT, mode, op1);
3644 /* Subtracting 0 has no effect. */
3645 if (op1 == CONST0_RTX (mode))
3648 /* See if this is something like X * C - X or vice versa or
3649 if the multiplication is written as a shift. If so, we can
3650 distribute and make a new multiply, shift, or maybe just
3651 have X (if C is 2 in the example above). But don't make
3652 real multiply if we didn't have one before. */
3654 if (! FLOAT_MODE_P (mode))
3656 HOST_WIDE_INT coeff0 = 1, coeff1 = 1;
3657 rtx lhs = op0, rhs = op1;
3660 if (GET_CODE (lhs) == NEG)
3661 coeff0 = -1, lhs = XEXP (lhs, 0);
3662 else if (GET_CODE (lhs) == MULT
3663 && GET_CODE (XEXP (lhs, 1)) == CONST_INT)
3665 coeff0 = INTVAL (XEXP (lhs, 1)), lhs = XEXP (lhs, 0);
3668 else if (GET_CODE (lhs) == ASHIFT
3669 && GET_CODE (XEXP (lhs, 1)) == CONST_INT
3670 && INTVAL (XEXP (lhs, 1)) >= 0
3671 && INTVAL (XEXP (lhs, 1)) < HOST_BITS_PER_WIDE_INT)
3673 coeff0 = ((HOST_WIDE_INT) 1) << INTVAL (XEXP (lhs, 1));
3674 lhs = XEXP (lhs, 0);
3677 if (GET_CODE (rhs) == NEG)
3678 coeff1 = - 1, rhs = XEXP (rhs, 0);
3679 else if (GET_CODE (rhs) == MULT
3680 && GET_CODE (XEXP (rhs, 1)) == CONST_INT)
3682 coeff1 = INTVAL (XEXP (rhs, 1)), rhs = XEXP (rhs, 0);
3685 else if (GET_CODE (rhs) == ASHIFT
3686 && GET_CODE (XEXP (rhs, 1)) == CONST_INT
3687 && INTVAL (XEXP (rhs, 1)) >= 0
3688 && INTVAL (XEXP (rhs, 1)) < HOST_BITS_PER_WIDE_INT)
3690 coeff1 = ((HOST_WIDE_INT) 1) << INTVAL (XEXP (rhs, 1));
3691 rhs = XEXP (rhs, 0);
3694 if (rtx_equal_p (lhs, rhs))
3696 tem = cse_gen_binary (MULT, mode, lhs,
3697 GEN_INT (coeff0 - coeff1));
3698 return (GET_CODE (tem) == MULT && ! had_mult) ? 0 : tem;
3702 /* (a - (-b)) -> (a + b). */
3703 if (GET_CODE (op1) == NEG)
3704 return cse_gen_binary (PLUS, mode, op0, XEXP (op1, 0));
3706 /* If one of the operands is a PLUS or a MINUS, see if we can
3707 simplify this by the associative law.
3708 Don't use the associative law for floating point.
3709 The inaccuracy makes it nonassociative,
3710 and subtle programs can break if operations are associated. */
3712 if (INTEGRAL_MODE_P (mode)
3713 && (GET_CODE (op0) == PLUS || GET_CODE (op0) == MINUS
3714 || GET_CODE (op1) == PLUS || GET_CODE (op1) == MINUS)
3715 && (tem = simplify_plus_minus (code, mode, op0, op1)) != 0)
3718 /* Don't let a relocatable value get a negative coeff. */
3719 if (GET_CODE (op1) == CONST_INT && GET_MODE (op0) != VOIDmode)
3720 return plus_constant (op0, - INTVAL (op1));
3724 if (op1 == constm1_rtx)
3726 tem = simplify_unary_operation (NEG, mode, op0, mode);
3728 return tem ? tem : gen_rtx (NEG, mode, op0);
3731 /* In IEEE floating point, x*0 is not always 0. */
3732 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3733 || ! FLOAT_MODE_P (mode) || flag_fast_math)
3734 && op1 == CONST0_RTX (mode)
3735 && ! side_effects_p (op0))
3738 /* In IEEE floating point, x*1 is not equivalent to x for nans.
3739 However, ANSI says we can drop signals,
3740 so we can do this anyway. */
3741 if (op1 == CONST1_RTX (mode))
3744 /* Convert multiply by constant power of two into shift unless
3745 we are still generating RTL. This test is a kludge. */
3746 if (GET_CODE (op1) == CONST_INT
3747 && (val = exact_log2 (INTVAL (op1))) >= 0
3748 && ! rtx_equal_function_value_matters)
3749 return gen_rtx (ASHIFT, mode, op0, GEN_INT (val));
3751 if (GET_CODE (op1) == CONST_DOUBLE
3752 && GET_MODE_CLASS (GET_MODE (op1)) == MODE_FLOAT)
3756 int op1is2, op1ism1;
3758 if (setjmp (handler))
3761 set_float_handler (handler);
3762 REAL_VALUE_FROM_CONST_DOUBLE (d, op1);
3763 op1is2 = REAL_VALUES_EQUAL (d, dconst2);
3764 op1ism1 = REAL_VALUES_EQUAL (d, dconstm1);
3765 set_float_handler (NULL_PTR);
3767 /* x*2 is x+x and x*(-1) is -x */
3768 if (op1is2 && GET_MODE (op0) == mode)
3769 return gen_rtx (PLUS, mode, op0, copy_rtx (op0));
3771 else if (op1ism1 && GET_MODE (op0) == mode)
3772 return gen_rtx (NEG, mode, op0);
3777 if (op1 == const0_rtx)
3779 if (GET_CODE (op1) == CONST_INT
3780 && (INTVAL (op1) & GET_MODE_MASK (mode)) == GET_MODE_MASK (mode))
3782 if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3784 /* A | (~A) -> -1 */
3785 if (((GET_CODE (op0) == NOT && rtx_equal_p (XEXP (op0, 0), op1))
3786 || (GET_CODE (op1) == NOT && rtx_equal_p (XEXP (op1, 0), op0)))
3787 && ! side_effects_p (op0)
3788 && GET_MODE_CLASS (mode) != MODE_CC)
3793 if (op1 == const0_rtx)
3795 if (GET_CODE (op1) == CONST_INT
3796 && (INTVAL (op1) & GET_MODE_MASK (mode)) == GET_MODE_MASK (mode))
3797 return gen_rtx (NOT, mode, op0);
3798 if (op0 == op1 && ! side_effects_p (op0)
3799 && GET_MODE_CLASS (mode) != MODE_CC)
3804 if (op1 == const0_rtx && ! side_effects_p (op0))
3806 if (GET_CODE (op1) == CONST_INT
3807 && (INTVAL (op1) & GET_MODE_MASK (mode)) == GET_MODE_MASK (mode))
3809 if (op0 == op1 && ! side_effects_p (op0)
3810 && GET_MODE_CLASS (mode) != MODE_CC)
3813 if (((GET_CODE (op0) == NOT && rtx_equal_p (XEXP (op0, 0), op1))
3814 || (GET_CODE (op1) == NOT && rtx_equal_p (XEXP (op1, 0), op0)))
3815 && ! side_effects_p (op0)
3816 && GET_MODE_CLASS (mode) != MODE_CC)
3821 /* Convert divide by power of two into shift (divide by 1 handled
3823 if (GET_CODE (op1) == CONST_INT
3824 && (arg1 = exact_log2 (INTVAL (op1))) > 0)
3825 return gen_rtx (LSHIFTRT, mode, op0, GEN_INT (arg1));
3827 /* ... fall through ... */
3830 if (op1 == CONST1_RTX (mode))
3833 /* In IEEE floating point, 0/x is not always 0. */
3834 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
3835 || ! FLOAT_MODE_P (mode) || flag_fast_math)
3836 && op0 == CONST0_RTX (mode)
3837 && ! side_effects_p (op1))
3840 #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
3841 /* Change division by a constant into multiplication. Only do
3842 this with -ffast-math until an expert says it is safe in
3844 else if (GET_CODE (op1) == CONST_DOUBLE
3845 && GET_MODE_CLASS (GET_MODE (op1)) == MODE_FLOAT
3846 && op1 != CONST0_RTX (mode)
3850 REAL_VALUE_FROM_CONST_DOUBLE (d, op1);
3852 if (! REAL_VALUES_EQUAL (d, dconst0))
3854 #if defined (REAL_ARITHMETIC)
3855 REAL_ARITHMETIC (d, rtx_to_tree_code (DIV), dconst1, d);
3856 return gen_rtx (MULT, mode, op0,
3857 CONST_DOUBLE_FROM_REAL_VALUE (d, mode));
3859 return gen_rtx (MULT, mode, op0,
3860 CONST_DOUBLE_FROM_REAL_VALUE (1./d, mode));
3868 /* Handle modulus by power of two (mod with 1 handled below). */
3869 if (GET_CODE (op1) == CONST_INT
3870 && exact_log2 (INTVAL (op1)) > 0)
3871 return gen_rtx (AND, mode, op0, GEN_INT (INTVAL (op1) - 1));
3873 /* ... fall through ... */
3876 if ((op0 == const0_rtx || op1 == const1_rtx)
3877 && ! side_effects_p (op0) && ! side_effects_p (op1))
3883 /* Rotating ~0 always results in ~0. */
3884 if (GET_CODE (op0) == CONST_INT && width <= HOST_BITS_PER_WIDE_INT
3885 && INTVAL (op0) == GET_MODE_MASK (mode)
3886 && ! side_effects_p (op1))
3889 /* ... fall through ... */
3894 if (op1 == const0_rtx)
3896 if (op0 == const0_rtx && ! side_effects_p (op1))
3901 if (width <= HOST_BITS_PER_WIDE_INT && GET_CODE (op1) == CONST_INT
3902 && INTVAL (op1) == (HOST_WIDE_INT) 1 << (width -1)
3903 && ! side_effects_p (op0))
3905 else if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3910 if (width <= HOST_BITS_PER_WIDE_INT && GET_CODE (op1) == CONST_INT
3912 == (unsigned HOST_WIDE_INT) GET_MODE_MASK (mode) >> 1)
3913 && ! side_effects_p (op0))
3915 else if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3920 if (op1 == const0_rtx && ! side_effects_p (op0))
3922 else if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3927 if (op1 == constm1_rtx && ! side_effects_p (op0))
3929 else if (rtx_equal_p (op0, op1) && ! side_effects_p (op0))
3940 /* Get the integer argument values in two forms:
3941 zero-extended in ARG0, ARG1 and sign-extended in ARG0S, ARG1S. */
3943 arg0 = INTVAL (op0);
3944 arg1 = INTVAL (op1);
3946 if (width < HOST_BITS_PER_WIDE_INT)
3948 arg0 &= ((HOST_WIDE_INT) 1 << width) - 1;
3949 arg1 &= ((HOST_WIDE_INT) 1 << width) - 1;
3952 if (arg0s & ((HOST_WIDE_INT) 1 << (width - 1)))
3953 arg0s |= ((HOST_WIDE_INT) (-1) << width);
3956 if (arg1s & ((HOST_WIDE_INT) 1 << (width - 1)))
3957 arg1s |= ((HOST_WIDE_INT) (-1) << width);
3965 /* Compute the value of the arithmetic. */
3970 val = arg0s + arg1s;
3974 val = arg0s - arg1s;
3978 val = arg0s * arg1s;
3984 val = arg0s / arg1s;
3990 val = arg0s % arg1s;
3996 val = (unsigned HOST_WIDE_INT) arg0 / arg1;
4002 val = (unsigned HOST_WIDE_INT) arg0 % arg1;
4018 /* If shift count is undefined, don't fold it; let the machine do
4019 what it wants. But truncate it if the machine will do that. */
4023 #ifdef SHIFT_COUNT_TRUNCATED
4024 if (SHIFT_COUNT_TRUNCATED)
4028 val = ((unsigned HOST_WIDE_INT) arg0) >> arg1;
4035 #ifdef SHIFT_COUNT_TRUNCATED
4036 if (SHIFT_COUNT_TRUNCATED)
4040 val = ((unsigned HOST_WIDE_INT) arg0) << arg1;
4047 #ifdef SHIFT_COUNT_TRUNCATED
4048 if (SHIFT_COUNT_TRUNCATED)
4052 val = arg0s >> arg1;
4054 /* Bootstrap compiler may not have sign extended the right shift.
4055 Manually extend the sign to insure bootstrap cc matches gcc. */
4056 if (arg0s < 0 && arg1 > 0)
4057 val |= ((HOST_WIDE_INT) -1) << (HOST_BITS_PER_WIDE_INT - arg1);
4066 val = ((((unsigned HOST_WIDE_INT) arg0) << (width - arg1))
4067 | (((unsigned HOST_WIDE_INT) arg0) >> arg1));
4075 val = ((((unsigned HOST_WIDE_INT) arg0) << arg1)
4076 | (((unsigned HOST_WIDE_INT) arg0) >> (width - arg1)));
4080 /* Do nothing here. */
4084 val = arg0s <= arg1s ? arg0s : arg1s;
4088 val = ((unsigned HOST_WIDE_INT) arg0
4089 <= (unsigned HOST_WIDE_INT) arg1 ? arg0 : arg1);
4093 val = arg0s > arg1s ? arg0s : arg1s;
4097 val = ((unsigned HOST_WIDE_INT) arg0
4098 > (unsigned HOST_WIDE_INT) arg1 ? arg0 : arg1);
4105 /* Clear the bits that don't belong in our mode, unless they and our sign
4106 bit are all one. So we get either a reasonable negative value or a
4107 reasonable unsigned value for this mode. */
4108 if (width < HOST_BITS_PER_WIDE_INT
4109 && ((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
4110 != ((HOST_WIDE_INT) (-1) << (width - 1))))
4111 val &= ((HOST_WIDE_INT) 1 << width) - 1;
4113 return GEN_INT (val);
4116 /* Simplify a PLUS or MINUS, at least one of whose operands may be another
4119 Rather than test for specific case, we do this by a brute-force method
4120 and do all possible simplifications until no more changes occur. Then
4121 we rebuild the operation. */
4124 simplify_plus_minus (code, mode, op0, op1)
4126 enum machine_mode mode;
4132 int n_ops = 2, input_ops = 2, input_consts = 0, n_consts = 0;
4133 int first = 1, negate = 0, changed;
4136 bzero ((char *) ops, sizeof ops);
4138 /* Set up the two operands and then expand them until nothing has been
4139 changed. If we run out of room in our array, give up; this should
4140 almost never happen. */
4142 ops[0] = op0, ops[1] = op1, negs[0] = 0, negs[1] = (code == MINUS);
4149 for (i = 0; i < n_ops; i++)
4150 switch (GET_CODE (ops[i]))
4157 ops[n_ops] = XEXP (ops[i], 1);
4158 negs[n_ops++] = GET_CODE (ops[i]) == MINUS ? !negs[i] : negs[i];
4159 ops[i] = XEXP (ops[i], 0);
4165 ops[i] = XEXP (ops[i], 0);
4166 negs[i] = ! negs[i];
4171 ops[i] = XEXP (ops[i], 0);
4177 /* ~a -> (-a - 1) */
4180 ops[n_ops] = constm1_rtx;
4181 negs[n_ops++] = negs[i];
4182 ops[i] = XEXP (ops[i], 0);
4183 negs[i] = ! negs[i];
4190 ops[i] = GEN_INT (- INTVAL (ops[i])), negs[i] = 0, changed = 1;
4195 /* If we only have two operands, we can't do anything. */
4199 /* Now simplify each pair of operands until nothing changes. The first
4200 time through just simplify constants against each other. */
4207 for (i = 0; i < n_ops - 1; i++)
4208 for (j = i + 1; j < n_ops; j++)
4209 if (ops[i] != 0 && ops[j] != 0
4210 && (! first || (CONSTANT_P (ops[i]) && CONSTANT_P (ops[j]))))
4212 rtx lhs = ops[i], rhs = ops[j];
4213 enum rtx_code ncode = PLUS;
4215 if (negs[i] && ! negs[j])
4216 lhs = ops[j], rhs = ops[i], ncode = MINUS;
4217 else if (! negs[i] && negs[j])
4220 tem = simplify_binary_operation (ncode, mode, lhs, rhs);
4223 ops[i] = tem, ops[j] = 0;
4224 negs[i] = negs[i] && negs[j];
4225 if (GET_CODE (tem) == NEG)
4226 ops[i] = XEXP (tem, 0), negs[i] = ! negs[i];
4228 if (GET_CODE (ops[i]) == CONST_INT && negs[i])
4229 ops[i] = GEN_INT (- INTVAL (ops[i])), negs[i] = 0;
4237 /* Pack all the operands to the lower-numbered entries and give up if
4238 we didn't reduce the number of operands we had. Make sure we
4239 count a CONST as two operands. If we have the same number of
4240 operands, but have made more CONSTs than we had, this is also
4241 an improvement, so accept it. */
4243 for (i = 0, j = 0; j < n_ops; j++)
4246 ops[i] = ops[j], negs[i++] = negs[j];
4247 if (GET_CODE (ops[j]) == CONST)
4251 if (i + n_consts > input_ops
4252 || (i + n_consts == input_ops && n_consts <= input_consts))
4257 /* If we have a CONST_INT, put it last. */
4258 for (i = 0; i < n_ops - 1; i++)
4259 if (GET_CODE (ops[i]) == CONST_INT)
4261 tem = ops[n_ops - 1], ops[n_ops - 1] = ops[i] , ops[i] = tem;
4262 j = negs[n_ops - 1], negs[n_ops - 1] = negs[i], negs[i] = j;
4265 /* Put a non-negated operand first. If there aren't any, make all
4266 operands positive and negate the whole thing later. */
4267 for (i = 0; i < n_ops && negs[i]; i++)
4272 for (i = 0; i < n_ops; i++)
4278 tem = ops[0], ops[0] = ops[i], ops[i] = tem;
4279 j = negs[0], negs[0] = negs[i], negs[i] = j;
4282 /* Now make the result by performing the requested operations. */
4284 for (i = 1; i < n_ops; i++)
4285 result = cse_gen_binary (negs[i] ? MINUS : PLUS, mode, result, ops[i]);
4287 return negate ? gen_rtx (NEG, mode, result) : result;
4290 /* Make a binary operation by properly ordering the operands and
4291 seeing if the expression folds. */
4294 cse_gen_binary (code, mode, op0, op1)
4296 enum machine_mode mode;
4301 /* Put complex operands first and constants second if commutative. */
4302 if (GET_RTX_CLASS (code) == 'c'
4303 && ((CONSTANT_P (op0) && GET_CODE (op1) != CONST_INT)
4304 || (GET_RTX_CLASS (GET_CODE (op0)) == 'o'
4305 && GET_RTX_CLASS (GET_CODE (op1)) != 'o')
4306 || (GET_CODE (op0) == SUBREG
4307 && GET_RTX_CLASS (GET_CODE (SUBREG_REG (op0))) == 'o'
4308 && GET_RTX_CLASS (GET_CODE (op1)) != 'o')))
4309 tem = op0, op0 = op1, op1 = tem;
4311 /* If this simplifies, do it. */
4312 tem = simplify_binary_operation (code, mode, op0, op1);
4317 /* Handle addition and subtraction of CONST_INT specially. Otherwise,
4318 just form the operation. */
4320 if (code == PLUS && GET_CODE (op1) == CONST_INT
4321 && GET_MODE (op0) != VOIDmode)
4322 return plus_constant (op0, INTVAL (op1));
4323 else if (code == MINUS && GET_CODE (op1) == CONST_INT
4324 && GET_MODE (op0) != VOIDmode)
4325 return plus_constant (op0, - INTVAL (op1));
4327 return gen_rtx (code, mode, op0, op1);
4330 /* Like simplify_binary_operation except used for relational operators.
4331 MODE is the mode of the operands, not that of the result. If MODE
4332 is VOIDmode, both operands must also be VOIDmode and we compare the
4333 operands in "infinite precision".
4335 If no simplification is possible, this function returns zero. Otherwise,
4336 it returns either const_true_rtx or const0_rtx. */
4339 simplify_relational_operation (code, mode, op0, op1)
4341 enum machine_mode mode;
4344 int equal, op0lt, op0ltu, op1lt, op1ltu;
4347 /* If op0 is a compare, extract the comparison arguments from it. */
4348 if (GET_CODE (op0) == COMPARE && op1 == const0_rtx)
4349 op1 = XEXP (op0, 1), op0 = XEXP (op0, 0);
4351 /* We can't simplify MODE_CC values since we don't know what the
4352 actual comparison is. */
4353 if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC
4360 /* For integer comparisons of A and B maybe we can simplify A - B and can
4361 then simplify a comparison of that with zero. If A and B are both either
4362 a register or a CONST_INT, this can't help; testing for these cases will
4363 prevent infinite recursion here and speed things up.
4365 If CODE is an unsigned comparison, we can only do this if A - B is a
4366 constant integer, and then we have to compare that integer with zero as a
4367 signed comparison. Note that this will give the incorrect result from
4368 comparisons that overflow. Since these are undefined, this is probably
4369 OK. If it causes a problem, we can check for A or B being an address
4370 (fp + const or SYMBOL_REF) and only do it in that case. */
4372 if (INTEGRAL_MODE_P (mode) && op1 != const0_rtx
4373 && ! ((GET_CODE (op0) == REG || GET_CODE (op0) == CONST_INT)
4374 && (GET_CODE (op1) == REG || GET_CODE (op1) == CONST_INT))
4375 && 0 != (tem = simplify_binary_operation (MINUS, mode, op0, op1))
4376 && (GET_CODE (tem) == CONST_INT
4377 || (code != GTU && code != GEU &&
4378 code != LTU && code != LEU)))
4379 return simplify_relational_operation (signed_condition (code),
4380 mode, tem, const0_rtx);
4382 /* For non-IEEE floating-point, if the two operands are equal, we know the
4384 if (rtx_equal_p (op0, op1)
4385 && (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
4386 || ! FLOAT_MODE_P (GET_MODE (op0)) || flag_fast_math))
4387 equal = 1, op0lt = 0, op0ltu = 0, op1lt = 0, op1ltu = 0;
4389 /* If the operands are floating-point constants, see if we can fold
4391 #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
4392 else if (GET_CODE (op0) == CONST_DOUBLE && GET_CODE (op1) == CONST_DOUBLE
4393 && GET_MODE_CLASS (GET_MODE (op0)) == MODE_FLOAT)
4395 REAL_VALUE_TYPE d0, d1;
4398 if (setjmp (handler))
4401 set_float_handler (handler);
4402 REAL_VALUE_FROM_CONST_DOUBLE (d0, op0);
4403 REAL_VALUE_FROM_CONST_DOUBLE (d1, op1);
4404 equal = REAL_VALUES_EQUAL (d0, d1);
4405 op0lt = op0ltu = REAL_VALUES_LESS (d0, d1);
4406 op1lt = op1ltu = REAL_VALUES_LESS (d1, d0);
4407 set_float_handler (NULL_PTR);
4409 #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
4411 /* Otherwise, see if the operands are both integers. */
4412 else if ((GET_MODE_CLASS (mode) == MODE_INT || mode == VOIDmode)
4413 && (GET_CODE (op0) == CONST_DOUBLE || GET_CODE (op0) == CONST_INT)
4414 && (GET_CODE (op1) == CONST_DOUBLE || GET_CODE (op1) == CONST_INT))
4416 int width = GET_MODE_BITSIZE (mode);
4417 HOST_WIDE_INT l0s, h0s, l1s, h1s;
4418 unsigned HOST_WIDE_INT l0u, h0u, l1u, h1u;
4420 /* Get the two words comprising each integer constant. */
4421 if (GET_CODE (op0) == CONST_DOUBLE)
4423 l0u = l0s = CONST_DOUBLE_LOW (op0);
4424 h0u = h0s = CONST_DOUBLE_HIGH (op0);
4428 l0u = l0s = INTVAL (op0);
4429 h0u = 0, h0s = l0s < 0 ? -1 : 0;
4432 if (GET_CODE (op1) == CONST_DOUBLE)
4434 l1u = l1s = CONST_DOUBLE_LOW (op1);
4435 h1u = h1s = CONST_DOUBLE_HIGH (op1);
4439 l1u = l1s = INTVAL (op1);
4440 h1u = 0, h1s = l1s < 0 ? -1 : 0;
4443 /* If WIDTH is nonzero and smaller than HOST_BITS_PER_WIDE_INT,
4444 we have to sign or zero-extend the values. */
4445 if (width != 0 && width <= HOST_BITS_PER_WIDE_INT)
4446 h0u = h1u = 0, h0s = l0s < 0 ? -1 : 0, h1s = l1s < 0 ? -1 : 0;
4448 if (width != 0 && width < HOST_BITS_PER_WIDE_INT)
4450 l0u &= ((HOST_WIDE_INT) 1 << width) - 1;
4451 l1u &= ((HOST_WIDE_INT) 1 << width) - 1;
4453 if (l0s & ((HOST_WIDE_INT) 1 << (width - 1)))
4454 l0s |= ((HOST_WIDE_INT) (-1) << width);
4456 if (l1s & ((HOST_WIDE_INT) 1 << (width - 1)))
4457 l1s |= ((HOST_WIDE_INT) (-1) << width);
4460 equal = (h0u == h1u && l0u == l1u);
4461 op0lt = (h0s < h1s || (h0s == h1s && l0s < l1s));
4462 op1lt = (h1s < h0s || (h1s == h0s && l1s < l0s));
4463 op0ltu = (h0u < h1u || (h0u == h1u && l0u < l1u));
4464 op1ltu = (h1u < h0u || (h1u == h0u && l1u < l0u));
4467 /* Otherwise, there are some code-specific tests we can make. */
4473 /* References to the frame plus a constant or labels cannot
4474 be zero, but a SYMBOL_REF can due to #pragma weak. */
4475 if (((NONZERO_BASE_PLUS_P (op0) && op1 == const0_rtx)
4476 || GET_CODE (op0) == LABEL_REF)
4477 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4478 /* On some machines, the ap reg can be 0 sometimes. */
4479 && op0 != arg_pointer_rtx
4486 if (((NONZERO_BASE_PLUS_P (op0) && op1 == const0_rtx)
4487 || GET_CODE (op0) == LABEL_REF)
4488 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4489 && op0 != arg_pointer_rtx
4492 return const_true_rtx;
4496 /* Unsigned values are never negative. */
4497 if (op1 == const0_rtx)
4498 return const_true_rtx;
4502 if (op1 == const0_rtx)
4507 /* Unsigned values are never greater than the largest
4509 if (GET_CODE (op1) == CONST_INT
4510 && INTVAL (op1) == GET_MODE_MASK (mode)
4511 && INTEGRAL_MODE_P (mode))
4512 return const_true_rtx;
4516 if (GET_CODE (op1) == CONST_INT
4517 && INTVAL (op1) == GET_MODE_MASK (mode)
4518 && INTEGRAL_MODE_P (mode))
4526 /* If we reach here, EQUAL, OP0LT, OP0LTU, OP1LT, and OP1LTU are set
4531 return equal ? const_true_rtx : const0_rtx;
4533 return ! equal ? const_true_rtx : const0_rtx;
4535 return op0lt ? const_true_rtx : const0_rtx;
4537 return op1lt ? const_true_rtx : const0_rtx;
4539 return op0ltu ? const_true_rtx : const0_rtx;
4541 return op1ltu ? const_true_rtx : const0_rtx;
4543 return equal || op0lt ? const_true_rtx : const0_rtx;
4545 return equal || op1lt ? const_true_rtx : const0_rtx;
4547 return equal || op0ltu ? const_true_rtx : const0_rtx;
4549 return equal || op1ltu ? const_true_rtx : const0_rtx;
4555 /* Simplify CODE, an operation with result mode MODE and three operands,
4556 OP0, OP1, and OP2. OP0_MODE was the mode of OP0 before it became
4557 a constant. Return 0 if no simplifications is possible. */
4560 simplify_ternary_operation (code, mode, op0_mode, op0, op1, op2)
4562 enum machine_mode mode, op0_mode;
4565 int width = GET_MODE_BITSIZE (mode);
4567 /* VOIDmode means "infinite" precision. */
4569 width = HOST_BITS_PER_WIDE_INT;
4575 if (GET_CODE (op0) == CONST_INT
4576 && GET_CODE (op1) == CONST_INT
4577 && GET_CODE (op2) == CONST_INT
4578 && INTVAL (op1) + INTVAL (op2) <= GET_MODE_BITSIZE (op0_mode)
4579 && width <= HOST_BITS_PER_WIDE_INT)
4581 /* Extracting a bit-field from a constant */
4582 HOST_WIDE_INT val = INTVAL (op0);
4585 val >>= (GET_MODE_BITSIZE (op0_mode) - INTVAL (op2) - INTVAL (op1));
4587 val >>= INTVAL (op2);
4589 if (HOST_BITS_PER_WIDE_INT != INTVAL (op1))
4591 /* First zero-extend. */
4592 val &= ((HOST_WIDE_INT) 1 << INTVAL (op1)) - 1;
4593 /* If desired, propagate sign bit. */
4594 if (code == SIGN_EXTRACT
4595 && (val & ((HOST_WIDE_INT) 1 << (INTVAL (op1) - 1))))
4596 val |= ~ (((HOST_WIDE_INT) 1 << INTVAL (op1)) - 1);
4599 /* Clear the bits that don't belong in our mode,
4600 unless they and our sign bit are all one.
4601 So we get either a reasonable negative value or a reasonable
4602 unsigned value for this mode. */
4603 if (width < HOST_BITS_PER_WIDE_INT
4604 && ((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
4605 != ((HOST_WIDE_INT) (-1) << (width - 1))))
4606 val &= ((HOST_WIDE_INT) 1 << width) - 1;
4608 return GEN_INT (val);
4613 if (GET_CODE (op0) == CONST_INT)
4614 return op0 != const0_rtx ? op1 : op2;
4624 /* If X is a nontrivial arithmetic operation on an argument
4625 for which a constant value can be determined, return
4626 the result of operating on that value, as a constant.
4627 Otherwise, return X, possibly with one or more operands
4628 modified by recursive calls to this function.
4630 If X is a register whose contents are known, we do NOT
4631 return those contents here. equiv_constant is called to
4634 INSN is the insn that we may be modifying. If it is 0, make a copy
4635 of X before modifying it. */
4642 register enum rtx_code code;
4643 register enum machine_mode mode;
4650 /* Folded equivalents of first two operands of X. */
4654 /* Constant equivalents of first three operands of X;
4655 0 when no such equivalent is known. */
4660 /* The mode of the first operand of X. We need this for sign and zero
4662 enum machine_mode mode_arg0;
4667 mode = GET_MODE (x);
4668 code = GET_CODE (x);
4677 /* No use simplifying an EXPR_LIST
4678 since they are used only for lists of args
4679 in a function call's REG_EQUAL note. */
4685 return prev_insn_cc0;
4689 /* If the next insn is a CODE_LABEL followed by a jump table,
4690 PC's value is a LABEL_REF pointing to that label. That
4691 lets us fold switch statements on the Vax. */
4692 if (insn && GET_CODE (insn) == JUMP_INSN)
4694 rtx next = next_nonnote_insn (insn);
4696 if (next && GET_CODE (next) == CODE_LABEL
4697 && NEXT_INSN (next) != 0
4698 && GET_CODE (NEXT_INSN (next)) == JUMP_INSN
4699 && (GET_CODE (PATTERN (NEXT_INSN (next))) == ADDR_VEC
4700 || GET_CODE (PATTERN (NEXT_INSN (next))) == ADDR_DIFF_VEC))
4701 return gen_rtx (LABEL_REF, Pmode, next);
4706 /* See if we previously assigned a constant value to this SUBREG. */
4707 if ((new = lookup_as_function (x, CONST_INT)) != 0
4708 || (new = lookup_as_function (x, CONST_DOUBLE)) != 0)
4711 /* If this is a paradoxical SUBREG, we have no idea what value the
4712 extra bits would have. However, if the operand is equivalent
4713 to a SUBREG whose operand is the same as our mode, and all the
4714 modes are within a word, we can just use the inner operand
4715 because these SUBREGs just say how to treat the register.
4717 Similarly if we find an integer constant. */
4719 if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
4721 enum machine_mode imode = GET_MODE (SUBREG_REG (x));
4722 struct table_elt *elt;
4724 if (GET_MODE_SIZE (mode) <= UNITS_PER_WORD
4725 && GET_MODE_SIZE (imode) <= UNITS_PER_WORD
4726 && (elt = lookup (SUBREG_REG (x), HASH (SUBREG_REG (x), imode),
4728 for (elt = elt->first_same_value;
4729 elt; elt = elt->next_same_value)
4731 if (CONSTANT_P (elt->exp)
4732 && GET_MODE (elt->exp) == VOIDmode)
4735 if (GET_CODE (elt->exp) == SUBREG
4736 && GET_MODE (SUBREG_REG (elt->exp)) == mode
4737 && exp_equiv_p (elt->exp, elt->exp, 1, 0))
4738 return copy_rtx (SUBREG_REG (elt->exp));
4744 /* Fold SUBREG_REG. If it changed, see if we can simplify the SUBREG.
4745 We might be able to if the SUBREG is extracting a single word in an
4746 integral mode or extracting the low part. */
4748 folded_arg0 = fold_rtx (SUBREG_REG (x), insn);
4749 const_arg0 = equiv_constant (folded_arg0);
4751 folded_arg0 = const_arg0;
4753 if (folded_arg0 != SUBREG_REG (x))
4757 if (GET_MODE_CLASS (mode) == MODE_INT
4758 && GET_MODE_SIZE (mode) == UNITS_PER_WORD
4759 && GET_MODE (SUBREG_REG (x)) != VOIDmode)
4760 new = operand_subword (folded_arg0, SUBREG_WORD (x), 0,
4761 GET_MODE (SUBREG_REG (x)));
4762 if (new == 0 && subreg_lowpart_p (x))
4763 new = gen_lowpart_if_possible (mode, folded_arg0);
4768 /* If this is a narrowing SUBREG and our operand is a REG, see if
4769 we can find an equivalence for REG that is an arithmetic operation
4770 in a wider mode where both operands are paradoxical SUBREGs
4771 from objects of our result mode. In that case, we couldn't report
4772 an equivalent value for that operation, since we don't know what the
4773 extra bits will be. But we can find an equivalence for this SUBREG
4774 by folding that operation is the narrow mode. This allows us to
4775 fold arithmetic in narrow modes when the machine only supports
4776 word-sized arithmetic.
4778 Also look for a case where we have a SUBREG whose operand is the
4779 same as our result. If both modes are smaller than a word, we
4780 are simply interpreting a register in different modes and we
4781 can use the inner value. */
4783 if (GET_CODE (folded_arg0) == REG
4784 && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (folded_arg0))
4785 && subreg_lowpart_p (x))
4787 struct table_elt *elt;
4789 /* We can use HASH here since we know that canon_hash won't be
4791 elt = lookup (folded_arg0,
4792 HASH (folded_arg0, GET_MODE (folded_arg0)),
4793 GET_MODE (folded_arg0));
4796 elt = elt->first_same_value;
4798 for (; elt; elt = elt->next_same_value)
4800 enum rtx_code eltcode = GET_CODE (elt->exp);
4802 /* Just check for unary and binary operations. */
4803 if (GET_RTX_CLASS (GET_CODE (elt->exp)) == '1'
4804 && GET_CODE (elt->exp) != SIGN_EXTEND
4805 && GET_CODE (elt->exp) != ZERO_EXTEND
4806 && GET_CODE (XEXP (elt->exp, 0)) == SUBREG
4807 && GET_MODE (SUBREG_REG (XEXP (elt->exp, 0))) == mode)
4809 rtx op0 = SUBREG_REG (XEXP (elt->exp, 0));
4811 if (GET_CODE (op0) != REG && ! CONSTANT_P (op0))
4812 op0 = fold_rtx (op0, NULL_RTX);
4814 op0 = equiv_constant (op0);
4816 new = simplify_unary_operation (GET_CODE (elt->exp), mode,
4819 else if ((GET_RTX_CLASS (GET_CODE (elt->exp)) == '2'
4820 || GET_RTX_CLASS (GET_CODE (elt->exp)) == 'c')
4821 && eltcode != DIV && eltcode != MOD
4822 && eltcode != UDIV && eltcode != UMOD
4823 && eltcode != ASHIFTRT && eltcode != LSHIFTRT
4824 && eltcode != ROTATE && eltcode != ROTATERT
4825 && ((GET_CODE (XEXP (elt->exp, 0)) == SUBREG
4826 && (GET_MODE (SUBREG_REG (XEXP (elt->exp, 0)))
4828 || CONSTANT_P (XEXP (elt->exp, 0)))
4829 && ((GET_CODE (XEXP (elt->exp, 1)) == SUBREG
4830 && (GET_MODE (SUBREG_REG (XEXP (elt->exp, 1)))
4832 || CONSTANT_P (XEXP (elt->exp, 1))))
4834 rtx op0 = gen_lowpart_common (mode, XEXP (elt->exp, 0));
4835 rtx op1 = gen_lowpart_common (mode, XEXP (elt->exp, 1));
4837 if (op0 && GET_CODE (op0) != REG && ! CONSTANT_P (op0))
4838 op0 = fold_rtx (op0, NULL_RTX);
4841 op0 = equiv_constant (op0);
4843 if (op1 && GET_CODE (op1) != REG && ! CONSTANT_P (op1))
4844 op1 = fold_rtx (op1, NULL_RTX);
4847 op1 = equiv_constant (op1);
4849 /* If we are looking for the low SImode part of
4850 (ashift:DI c (const_int 32)), it doesn't work
4851 to compute that in SImode, because a 32-bit shift
4852 in SImode is unpredictable. We know the value is 0. */
4854 && GET_CODE (elt->exp) == ASHIFT
4855 && GET_CODE (op1) == CONST_INT
4856 && INTVAL (op1) >= GET_MODE_BITSIZE (mode))
4858 if (INTVAL (op1) < GET_MODE_BITSIZE (GET_MODE (elt->exp)))
4860 /* If the count fits in the inner mode's width,
4861 but exceeds the outer mode's width,
4862 the value will get truncated to 0
4866 /* If the count exceeds even the inner mode's width,
4867 don't fold this expression. */
4870 else if (op0 && op1)
4871 new = simplify_binary_operation (GET_CODE (elt->exp), mode,
4875 else if (GET_CODE (elt->exp) == SUBREG
4876 && GET_MODE (SUBREG_REG (elt->exp)) == mode
4877 && (GET_MODE_SIZE (GET_MODE (folded_arg0))
4879 && exp_equiv_p (elt->exp, elt->exp, 1, 0))
4880 new = copy_rtx (SUBREG_REG (elt->exp));
4891 /* If we have (NOT Y), see if Y is known to be (NOT Z).
4892 If so, (NOT Y) simplifies to Z. Similarly for NEG. */
4893 new = lookup_as_function (XEXP (x, 0), code);
4895 return fold_rtx (copy_rtx (XEXP (new, 0)), insn);
4899 /* If we are not actually processing an insn, don't try to find the
4900 best address. Not only don't we care, but we could modify the
4901 MEM in an invalid way since we have no insn to validate against. */
4903 find_best_addr (insn, &XEXP (x, 0));
4906 /* Even if we don't fold in the insn itself,
4907 we can safely do so here, in hopes of getting a constant. */
4908 rtx addr = fold_rtx (XEXP (x, 0), NULL_RTX);
4910 HOST_WIDE_INT offset = 0;
4912 if (GET_CODE (addr) == REG
4913 && REGNO_QTY_VALID_P (REGNO (addr))
4914 && GET_MODE (addr) == qty_mode[reg_qty[REGNO (addr)]]
4915 && qty_const[reg_qty[REGNO (addr)]] != 0)
4916 addr = qty_const[reg_qty[REGNO (addr)]];
4918 /* If address is constant, split it into a base and integer offset. */
4919 if (GET_CODE (addr) == SYMBOL_REF || GET_CODE (addr) == LABEL_REF)
4921 else if (GET_CODE (addr) == CONST && GET_CODE (XEXP (addr, 0)) == PLUS
4922 && GET_CODE (XEXP (XEXP (addr, 0), 1)) == CONST_INT)
4924 base = XEXP (XEXP (addr, 0), 0);
4925 offset = INTVAL (XEXP (XEXP (addr, 0), 1));
4927 else if (GET_CODE (addr) == LO_SUM
4928 && GET_CODE (XEXP (addr, 1)) == SYMBOL_REF)
4929 base = XEXP (addr, 1);
4931 /* If this is a constant pool reference, we can fold it into its
4932 constant to allow better value tracking. */
4933 if (base && GET_CODE (base) == SYMBOL_REF
4934 && CONSTANT_POOL_ADDRESS_P (base))
4936 rtx constant = get_pool_constant (base);
4937 enum machine_mode const_mode = get_pool_mode (base);
4940 if (CONSTANT_P (constant) && GET_CODE (constant) != CONST_INT)
4941 constant_pool_entries_cost = COST (constant);
4943 /* If we are loading the full constant, we have an equivalence. */
4944 if (offset == 0 && mode == const_mode)
4947 /* If this actually isn't a constant (wierd!), we can't do
4948 anything. Otherwise, handle the two most common cases:
4949 extracting a word from a multi-word constant, and extracting
4950 the low-order bits. Other cases don't seem common enough to
4952 if (! CONSTANT_P (constant))
4955 if (GET_MODE_CLASS (mode) == MODE_INT
4956 && GET_MODE_SIZE (mode) == UNITS_PER_WORD
4957 && offset % UNITS_PER_WORD == 0
4958 && (new = operand_subword (constant,
4959 offset / UNITS_PER_WORD,
4960 0, const_mode)) != 0)
4963 if (((BYTES_BIG_ENDIAN
4964 && offset == GET_MODE_SIZE (GET_MODE (constant)) - 1)
4965 || (! BYTES_BIG_ENDIAN && offset == 0))
4966 && (new = gen_lowpart_if_possible (mode, constant)) != 0)
4970 /* If this is a reference to a label at a known position in a jump
4971 table, we also know its value. */
4972 if (base && GET_CODE (base) == LABEL_REF)
4974 rtx label = XEXP (base, 0);
4975 rtx table_insn = NEXT_INSN (label);
4977 if (table_insn && GET_CODE (table_insn) == JUMP_INSN
4978 && GET_CODE (PATTERN (table_insn)) == ADDR_VEC)
4980 rtx table = PATTERN (table_insn);
4983 && (offset / GET_MODE_SIZE (GET_MODE (table))
4984 < XVECLEN (table, 0)))
4985 return XVECEXP (table, 0,
4986 offset / GET_MODE_SIZE (GET_MODE (table)));
4988 if (table_insn && GET_CODE (table_insn) == JUMP_INSN
4989 && GET_CODE (PATTERN (table_insn)) == ADDR_DIFF_VEC)
4991 rtx table = PATTERN (table_insn);
4994 && (offset / GET_MODE_SIZE (GET_MODE (table))
4995 < XVECLEN (table, 1)))
4997 offset /= GET_MODE_SIZE (GET_MODE (table));
4998 new = gen_rtx (MINUS, Pmode, XVECEXP (table, 1, offset),
5001 if (GET_MODE (table) != Pmode)
5002 new = gen_rtx (TRUNCATE, GET_MODE (table), new);
5016 mode_arg0 = VOIDmode;
5018 /* Try folding our operands.
5019 Then see which ones have constant values known. */
5021 fmt = GET_RTX_FORMAT (code);
5022 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5025 rtx arg = XEXP (x, i);
5026 rtx folded_arg = arg, const_arg = 0;
5027 enum machine_mode mode_arg = GET_MODE (arg);
5028 rtx cheap_arg, expensive_arg;
5029 rtx replacements[2];
5032 /* Most arguments are cheap, so handle them specially. */
5033 switch (GET_CODE (arg))
5036 /* This is the same as calling equiv_constant; it is duplicated
5038 if (REGNO_QTY_VALID_P (REGNO (arg))
5039 && qty_const[reg_qty[REGNO (arg)]] != 0
5040 && GET_CODE (qty_const[reg_qty[REGNO (arg)]]) != REG
5041 && GET_CODE (qty_const[reg_qty[REGNO (arg)]]) != PLUS)
5043 = gen_lowpart_if_possible (GET_MODE (arg),
5044 qty_const[reg_qty[REGNO (arg)]]);
5057 folded_arg = prev_insn_cc0;
5058 mode_arg = prev_insn_cc0_mode;
5059 const_arg = equiv_constant (folded_arg);
5064 folded_arg = fold_rtx (arg, insn);
5065 const_arg = equiv_constant (folded_arg);
5068 /* For the first three operands, see if the operand
5069 is constant or equivalent to a constant. */
5073 folded_arg0 = folded_arg;
5074 const_arg0 = const_arg;
5075 mode_arg0 = mode_arg;
5078 folded_arg1 = folded_arg;
5079 const_arg1 = const_arg;
5082 const_arg2 = const_arg;
5086 /* Pick the least expensive of the folded argument and an
5087 equivalent constant argument. */
5088 if (const_arg == 0 || const_arg == folded_arg
5089 || COST (const_arg) > COST (folded_arg))
5090 cheap_arg = folded_arg, expensive_arg = const_arg;
5092 cheap_arg = const_arg, expensive_arg = folded_arg;
5094 /* Try to replace the operand with the cheapest of the two
5095 possibilities. If it doesn't work and this is either of the first
5096 two operands of a commutative operation, try swapping them.
5097 If THAT fails, try the more expensive, provided it is cheaper
5098 than what is already there. */
5100 if (cheap_arg == XEXP (x, i))
5103 if (insn == 0 && ! copied)
5109 replacements[0] = cheap_arg, replacements[1] = expensive_arg;
5111 j < 2 && replacements[j]
5112 && COST (replacements[j]) < COST (XEXP (x, i));
5115 if (validate_change (insn, &XEXP (x, i), replacements[j], 0))
5118 if (code == NE || code == EQ || GET_RTX_CLASS (code) == 'c')
5120 validate_change (insn, &XEXP (x, i), XEXP (x, 1 - i), 1);
5121 validate_change (insn, &XEXP (x, 1 - i), replacements[j], 1);
5123 if (apply_change_group ())
5125 /* Swap them back to be invalid so that this loop can
5126 continue and flag them to be swapped back later. */
5129 tem = XEXP (x, 0); XEXP (x, 0) = XEXP (x, 1);
5138 else if (fmt[i] == 'E')
5139 /* Don't try to fold inside of a vector of expressions.
5140 Doing nothing is harmless. */
5143 /* If a commutative operation, place a constant integer as the second
5144 operand unless the first operand is also a constant integer. Otherwise,
5145 place any constant second unless the first operand is also a constant. */
5147 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
5149 if (must_swap || (const_arg0
5151 || (GET_CODE (const_arg0) == CONST_INT
5152 && GET_CODE (const_arg1) != CONST_INT))))
5154 register rtx tem = XEXP (x, 0);
5156 if (insn == 0 && ! copied)
5162 validate_change (insn, &XEXP (x, 0), XEXP (x, 1), 1);
5163 validate_change (insn, &XEXP (x, 1), tem, 1);
5164 if (apply_change_group ())
5166 tem = const_arg0, const_arg0 = const_arg1, const_arg1 = tem;
5167 tem = folded_arg0, folded_arg0 = folded_arg1, folded_arg1 = tem;
5172 /* If X is an arithmetic operation, see if we can simplify it. */
5174 switch (GET_RTX_CLASS (code))
5177 /* We can't simplify extension ops unless we know the original mode. */
5178 if ((code == ZERO_EXTEND || code == SIGN_EXTEND)
5179 && mode_arg0 == VOIDmode)
5181 new = simplify_unary_operation (code, mode,
5182 const_arg0 ? const_arg0 : folded_arg0,
5187 /* See what items are actually being compared and set FOLDED_ARG[01]
5188 to those values and CODE to the actual comparison code. If any are
5189 constant, set CONST_ARG0 and CONST_ARG1 appropriately. We needn't
5190 do anything if both operands are already known to be constant. */
5192 if (const_arg0 == 0 || const_arg1 == 0)
5194 struct table_elt *p0, *p1;
5195 rtx true = const_true_rtx, false = const0_rtx;
5196 enum machine_mode mode_arg1;
5198 #ifdef FLOAT_STORE_FLAG_VALUE
5199 if (GET_MODE_CLASS (mode) == MODE_FLOAT)
5201 true = CONST_DOUBLE_FROM_REAL_VALUE (FLOAT_STORE_FLAG_VALUE,
5203 false = CONST0_RTX (mode);
5207 code = find_comparison_args (code, &folded_arg0, &folded_arg1,
5208 &mode_arg0, &mode_arg1);
5209 const_arg0 = equiv_constant (folded_arg0);
5210 const_arg1 = equiv_constant (folded_arg1);
5212 /* If the mode is VOIDmode or a MODE_CC mode, we don't know
5213 what kinds of things are being compared, so we can't do
5214 anything with this comparison. */
5216 if (mode_arg0 == VOIDmode || GET_MODE_CLASS (mode_arg0) == MODE_CC)
5219 /* If we do not now have two constants being compared, see if we
5220 can nevertheless deduce some things about the comparison. */
5221 if (const_arg0 == 0 || const_arg1 == 0)
5223 /* Is FOLDED_ARG0 frame-pointer plus a constant? Or non-explicit
5224 constant? These aren't zero, but we don't know their sign. */
5225 if (const_arg1 == const0_rtx
5226 && (NONZERO_BASE_PLUS_P (folded_arg0)
5227 #if 0 /* Sad to say, on sysvr4, #pragma weak can make a symbol address
5229 || GET_CODE (folded_arg0) == SYMBOL_REF
5231 || GET_CODE (folded_arg0) == LABEL_REF
5232 || GET_CODE (folded_arg0) == CONST))
5236 else if (code == NE)
5240 /* See if the two operands are the same. We don't do this
5241 for IEEE floating-point since we can't assume x == x
5242 since x might be a NaN. */
5244 if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
5245 || ! FLOAT_MODE_P (mode_arg0) || flag_fast_math)
5246 && (folded_arg0 == folded_arg1
5247 || (GET_CODE (folded_arg0) == REG
5248 && GET_CODE (folded_arg1) == REG
5249 && (reg_qty[REGNO (folded_arg0)]
5250 == reg_qty[REGNO (folded_arg1)]))
5251 || ((p0 = lookup (folded_arg0,
5252 (safe_hash (folded_arg0, mode_arg0)
5253 % NBUCKETS), mode_arg0))
5254 && (p1 = lookup (folded_arg1,
5255 (safe_hash (folded_arg1, mode_arg0)
5256 % NBUCKETS), mode_arg0))
5257 && p0->first_same_value == p1->first_same_value)))
5258 return ((code == EQ || code == LE || code == GE
5259 || code == LEU || code == GEU)
5262 /* If FOLDED_ARG0 is a register, see if the comparison we are
5263 doing now is either the same as we did before or the reverse
5264 (we only check the reverse if not floating-point). */
5265 else if (GET_CODE (folded_arg0) == REG)
5267 int qty = reg_qty[REGNO (folded_arg0)];
5269 if (REGNO_QTY_VALID_P (REGNO (folded_arg0))
5270 && (comparison_dominates_p (qty_comparison_code[qty], code)
5271 || (comparison_dominates_p (qty_comparison_code[qty],
5272 reverse_condition (code))
5273 && ! FLOAT_MODE_P (mode_arg0)))
5274 && (rtx_equal_p (qty_comparison_const[qty], folded_arg1)
5276 && rtx_equal_p (qty_comparison_const[qty],
5278 || (GET_CODE (folded_arg1) == REG
5279 && (reg_qty[REGNO (folded_arg1)]
5280 == qty_comparison_qty[qty]))))
5281 return (comparison_dominates_p (qty_comparison_code[qty],
5288 /* If we are comparing against zero, see if the first operand is
5289 equivalent to an IOR with a constant. If so, we may be able to
5290 determine the result of this comparison. */
5292 if (const_arg1 == const0_rtx)
5294 rtx y = lookup_as_function (folded_arg0, IOR);
5298 && (inner_const = equiv_constant (XEXP (y, 1))) != 0
5299 && GET_CODE (inner_const) == CONST_INT
5300 && INTVAL (inner_const) != 0)
5302 int sign_bitnum = GET_MODE_BITSIZE (mode_arg0) - 1;
5303 int has_sign = (HOST_BITS_PER_WIDE_INT >= sign_bitnum
5304 && (INTVAL (inner_const)
5305 & ((HOST_WIDE_INT) 1 << sign_bitnum)));
5306 rtx true = const_true_rtx, false = const0_rtx;
5308 #ifdef FLOAT_STORE_FLAG_VALUE
5309 if (GET_MODE_CLASS (mode) == MODE_FLOAT)
5311 true = CONST_DOUBLE_FROM_REAL_VALUE (FLOAT_STORE_FLAG_VALUE,
5313 false = CONST0_RTX (mode);
5335 new = simplify_relational_operation (code, mode_arg0,
5336 const_arg0 ? const_arg0 : folded_arg0,
5337 const_arg1 ? const_arg1 : folded_arg1);
5338 #ifdef FLOAT_STORE_FLAG_VALUE
5339 if (new != 0 && GET_MODE_CLASS (mode) == MODE_FLOAT)
5340 new = ((new == const0_rtx) ? CONST0_RTX (mode)
5341 : CONST_DOUBLE_FROM_REAL_VALUE (FLOAT_STORE_FLAG_VALUE, mode));
5350 /* If the second operand is a LABEL_REF, see if the first is a MINUS
5351 with that LABEL_REF as its second operand. If so, the result is
5352 the first operand of that MINUS. This handles switches with an
5353 ADDR_DIFF_VEC table. */
5354 if (const_arg1 && GET_CODE (const_arg1) == LABEL_REF)
5356 rtx y = lookup_as_function (folded_arg0, MINUS);
5358 if (y != 0 && GET_CODE (XEXP (y, 1)) == LABEL_REF
5359 && XEXP (XEXP (y, 1), 0) == XEXP (const_arg1, 0))
5363 /* If second operand is a register equivalent to a negative
5364 CONST_INT, see if we can find a register equivalent to the
5365 positive constant. Make a MINUS if so. Don't do this for
5366 a negative constant since we might then alternate between
5367 chosing positive and negative constants. Having the positive
5368 constant previously-used is the more common case. */
5369 if (const_arg1 && GET_CODE (const_arg1) == CONST_INT
5370 && INTVAL (const_arg1) < 0 && GET_CODE (folded_arg1) == REG)
5372 rtx new_const = GEN_INT (- INTVAL (const_arg1));
5374 = lookup (new_const, safe_hash (new_const, mode) % NBUCKETS,
5378 for (p = p->first_same_value; p; p = p->next_same_value)
5379 if (GET_CODE (p->exp) == REG)
5380 return cse_gen_binary (MINUS, mode, folded_arg0,
5381 canon_reg (p->exp, NULL_RTX));
5386 /* If we have (MINUS Y C), see if Y is known to be (PLUS Z C2).
5387 If so, produce (PLUS Z C2-C). */
5388 if (const_arg1 != 0 && GET_CODE (const_arg1) == CONST_INT)
5390 rtx y = lookup_as_function (XEXP (x, 0), PLUS);
5391 if (y && GET_CODE (XEXP (y, 1)) == CONST_INT)
5392 return fold_rtx (plus_constant (copy_rtx (y),
5393 -INTVAL (const_arg1)),
5397 /* ... fall through ... */
5400 case SMIN: case SMAX: case UMIN: case UMAX:
5401 case IOR: case AND: case XOR:
5402 case MULT: case DIV: case UDIV:
5403 case ASHIFT: case LSHIFTRT: case ASHIFTRT:
5404 /* If we have (<op> <reg> <const_int>) for an associative OP and REG
5405 is known to be of similar form, we may be able to replace the
5406 operation with a combined operation. This may eliminate the
5407 intermediate operation if every use is simplified in this way.
5408 Note that the similar optimization done by combine.c only works
5409 if the intermediate operation's result has only one reference. */
5411 if (GET_CODE (folded_arg0) == REG
5412 && const_arg1 && GET_CODE (const_arg1) == CONST_INT)
5415 = (code == ASHIFT || code == ASHIFTRT || code == LSHIFTRT);
5416 rtx y = lookup_as_function (folded_arg0, code);
5418 enum rtx_code associate_code;
5422 || 0 == (inner_const
5423 = equiv_constant (fold_rtx (XEXP (y, 1), 0)))
5424 || GET_CODE (inner_const) != CONST_INT
5425 /* If we have compiled a statement like
5426 "if (x == (x & mask1))", and now are looking at
5427 "x & mask2", we will have a case where the first operand
5428 of Y is the same as our first operand. Unless we detect
5429 this case, an infinite loop will result. */
5430 || XEXP (y, 0) == folded_arg0)
5433 /* Don't associate these operations if they are a PLUS with the
5434 same constant and it is a power of two. These might be doable
5435 with a pre- or post-increment. Similarly for two subtracts of
5436 identical powers of two with post decrement. */
5438 if (code == PLUS && INTVAL (const_arg1) == INTVAL (inner_const)
5440 #if defined(HAVE_PRE_INCREMENT) || defined(HAVE_POST_INCREMENT)
5441 || exact_log2 (INTVAL (const_arg1)) >= 0
5443 #if defined(HAVE_PRE_DECREMENT) || defined(HAVE_POST_DECREMENT)
5444 || exact_log2 (- INTVAL (const_arg1)) >= 0
5449 /* Compute the code used to compose the constants. For example,
5450 A/C1/C2 is A/(C1 * C2), so if CODE == DIV, we want MULT. */
5453 = (code == MULT || code == DIV || code == UDIV ? MULT
5454 : is_shift || code == PLUS || code == MINUS ? PLUS : code);
5456 new_const = simplify_binary_operation (associate_code, mode,
5457 const_arg1, inner_const);
5462 /* If we are associating shift operations, don't let this
5463 produce a shift of the size of the object or larger.
5464 This could occur when we follow a sign-extend by a right
5465 shift on a machine that does a sign-extend as a pair
5468 if (is_shift && GET_CODE (new_const) == CONST_INT
5469 && INTVAL (new_const) >= GET_MODE_BITSIZE (mode))
5471 /* As an exception, we can turn an ASHIFTRT of this
5472 form into a shift of the number of bits - 1. */
5473 if (code == ASHIFTRT)
5474 new_const = GEN_INT (GET_MODE_BITSIZE (mode) - 1);
5479 y = copy_rtx (XEXP (y, 0));
5481 /* If Y contains our first operand (the most common way this
5482 can happen is if Y is a MEM), we would do into an infinite
5483 loop if we tried to fold it. So don't in that case. */
5485 if (! reg_mentioned_p (folded_arg0, y))
5486 y = fold_rtx (y, insn);
5488 return cse_gen_binary (code, mode, y, new_const);
5492 new = simplify_binary_operation (code, mode,
5493 const_arg0 ? const_arg0 : folded_arg0,
5494 const_arg1 ? const_arg1 : folded_arg1);
5498 /* (lo_sum (high X) X) is simply X. */
5499 if (code == LO_SUM && const_arg0 != 0
5500 && GET_CODE (const_arg0) == HIGH
5501 && rtx_equal_p (XEXP (const_arg0, 0), const_arg1))
5507 new = simplify_ternary_operation (code, mode, mode_arg0,
5508 const_arg0 ? const_arg0 : folded_arg0,
5509 const_arg1 ? const_arg1 : folded_arg1,
5510 const_arg2 ? const_arg2 : XEXP (x, 2));
5514 return new ? new : x;
5517 /* Return a constant value currently equivalent to X.
5518 Return 0 if we don't know one. */
5524 if (GET_CODE (x) == REG
5525 && REGNO_QTY_VALID_P (REGNO (x))
5526 && qty_const[reg_qty[REGNO (x)]])
5527 x = gen_lowpart_if_possible (GET_MODE (x), qty_const[reg_qty[REGNO (x)]]);
5529 if (x != 0 && CONSTANT_P (x))
5532 /* If X is a MEM, try to fold it outside the context of any insn to see if
5533 it might be equivalent to a constant. That handles the case where it
5534 is a constant-pool reference. Then try to look it up in the hash table
5535 in case it is something whose value we have seen before. */
5537 if (GET_CODE (x) == MEM)
5539 struct table_elt *elt;
5541 x = fold_rtx (x, NULL_RTX);
5545 elt = lookup (x, safe_hash (x, GET_MODE (x)) % NBUCKETS, GET_MODE (x));
5549 for (elt = elt->first_same_value; elt; elt = elt->next_same_value)
5550 if (elt->is_const && CONSTANT_P (elt->exp))
5557 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point
5558 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the
5559 least-significant part of X.
5560 MODE specifies how big a part of X to return.
5562 If the requested operation cannot be done, 0 is returned.
5564 This is similar to gen_lowpart in emit-rtl.c. */
5567 gen_lowpart_if_possible (mode, x)
5568 enum machine_mode mode;
5571 rtx result = gen_lowpart_common (mode, x);
5575 else if (GET_CODE (x) == MEM)
5577 /* This is the only other case we handle. */
5578 register int offset = 0;
5581 #if WORDS_BIG_ENDIAN
5582 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
5583 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
5585 #if BYTES_BIG_ENDIAN
5586 /* Adjust the address so that the address-after-the-data
5588 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
5589 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
5591 new = gen_rtx (MEM, mode, plus_constant (XEXP (x, 0), offset));
5592 if (! memory_address_p (mode, XEXP (new, 0)))
5594 MEM_VOLATILE_P (new) = MEM_VOLATILE_P (x);
5595 RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (x);
5596 MEM_IN_STRUCT_P (new) = MEM_IN_STRUCT_P (x);
5603 /* Given INSN, a jump insn, TAKEN indicates if we are following the "taken"
5604 branch. It will be zero if not.
5606 In certain cases, this can cause us to add an equivalence. For example,
5607 if we are following the taken case of
5609 we can add the fact that `i' and '2' are now equivalent.
5611 In any case, we can record that this comparison was passed. If the same
5612 comparison is seen later, we will know its value. */
5615 record_jump_equiv (insn, taken)
5619 int cond_known_true;
5621 enum machine_mode mode, mode0, mode1;
5622 int reversed_nonequality = 0;
5625 /* Ensure this is the right kind of insn. */
5626 if (! condjump_p (insn) || simplejump_p (insn))
5629 /* See if this jump condition is known true or false. */
5631 cond_known_true = (XEXP (SET_SRC (PATTERN (insn)), 2) == pc_rtx);
5633 cond_known_true = (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx);
5635 /* Get the type of comparison being done and the operands being compared.
5636 If we had to reverse a non-equality condition, record that fact so we
5637 know that it isn't valid for floating-point. */
5638 code = GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 0));
5639 op0 = fold_rtx (XEXP (XEXP (SET_SRC (PATTERN (insn)), 0), 0), insn);
5640 op1 = fold_rtx (XEXP (XEXP (SET_SRC (PATTERN (insn)), 0), 1), insn);
5642 code = find_comparison_args (code, &op0, &op1, &mode0, &mode1);
5643 if (! cond_known_true)
5645 reversed_nonequality = (code != EQ && code != NE);
5646 code = reverse_condition (code);
5649 /* The mode is the mode of the non-constant. */
5651 if (mode1 != VOIDmode)
5654 record_jump_cond (code, mode, op0, op1, reversed_nonequality);
5657 /* We know that comparison CODE applied to OP0 and OP1 in MODE is true.
5658 REVERSED_NONEQUALITY is nonzero if CODE had to be swapped.
5659 Make any useful entries we can with that information. Called from
5660 above function and called recursively. */
5663 record_jump_cond (code, mode, op0, op1, reversed_nonequality)
5665 enum machine_mode mode;
5667 int reversed_nonequality;
5669 unsigned op0_hash, op1_hash;
5670 int op0_in_memory, op0_in_struct, op1_in_memory, op1_in_struct;
5671 struct table_elt *op0_elt, *op1_elt;
5673 /* If OP0 and OP1 are known equal, and either is a paradoxical SUBREG,
5674 we know that they are also equal in the smaller mode (this is also
5675 true for all smaller modes whether or not there is a SUBREG, but
5676 is not worth testing for with no SUBREG. */
5678 /* Note that GET_MODE (op0) may not equal MODE. */
5679 if (code == EQ && GET_CODE (op0) == SUBREG
5680 && (GET_MODE_SIZE (GET_MODE (op0))
5681 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0)))))
5683 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op0));
5684 rtx tem = gen_lowpart_if_possible (inner_mode, op1);
5686 record_jump_cond (code, mode, SUBREG_REG (op0),
5687 tem ? tem : gen_rtx (SUBREG, inner_mode, op1, 0),
5688 reversed_nonequality);
5691 if (code == EQ && GET_CODE (op1) == SUBREG
5692 && (GET_MODE_SIZE (GET_MODE (op1))
5693 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op1)))))
5695 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op1));
5696 rtx tem = gen_lowpart_if_possible (inner_mode, op0);
5698 record_jump_cond (code, mode, SUBREG_REG (op1),
5699 tem ? tem : gen_rtx (SUBREG, inner_mode, op0, 0),
5700 reversed_nonequality);
5703 /* Similarly, if this is an NE comparison, and either is a SUBREG
5704 making a smaller mode, we know the whole thing is also NE. */
5706 /* Note that GET_MODE (op0) may not equal MODE;
5707 if we test MODE instead, we can get an infinite recursion
5708 alternating between two modes each wider than MODE. */
5710 if (code == NE && GET_CODE (op0) == SUBREG
5711 && subreg_lowpart_p (op0)
5712 && (GET_MODE_SIZE (GET_MODE (op0))
5713 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0)))))
5715 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op0));
5716 rtx tem = gen_lowpart_if_possible (inner_mode, op1);
5718 record_jump_cond (code, mode, SUBREG_REG (op0),
5719 tem ? tem : gen_rtx (SUBREG, inner_mode, op1, 0),
5720 reversed_nonequality);
5723 if (code == NE && GET_CODE (op1) == SUBREG
5724 && subreg_lowpart_p (op1)
5725 && (GET_MODE_SIZE (GET_MODE (op1))
5726 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op1)))))
5728 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op1));
5729 rtx tem = gen_lowpart_if_possible (inner_mode, op0);
5731 record_jump_cond (code, mode, SUBREG_REG (op1),
5732 tem ? tem : gen_rtx (SUBREG, inner_mode, op0, 0),
5733 reversed_nonequality);
5736 /* Hash both operands. */
5739 hash_arg_in_memory = 0;
5740 hash_arg_in_struct = 0;
5741 op0_hash = HASH (op0, mode);
5742 op0_in_memory = hash_arg_in_memory;
5743 op0_in_struct = hash_arg_in_struct;
5749 hash_arg_in_memory = 0;
5750 hash_arg_in_struct = 0;
5751 op1_hash = HASH (op1, mode);
5752 op1_in_memory = hash_arg_in_memory;
5753 op1_in_struct = hash_arg_in_struct;
5758 /* Look up both operands. */
5759 op0_elt = lookup (op0, op0_hash, mode);
5760 op1_elt = lookup (op1, op1_hash, mode);
5762 /* If we aren't setting two things equal all we can do is save this
5763 comparison. Similarly if this is floating-point. In the latter
5764 case, OP1 might be zero and both -0.0 and 0.0 are equal to it.
5765 If we record the equality, we might inadvertently delete code
5766 whose intent was to change -0 to +0. */
5768 if (code != EQ || FLOAT_MODE_P (GET_MODE (op0)))
5770 /* If we reversed a floating-point comparison, if OP0 is not a
5771 register, or if OP1 is neither a register or constant, we can't
5774 if (GET_CODE (op1) != REG)
5775 op1 = equiv_constant (op1);
5777 if ((reversed_nonequality && FLOAT_MODE_P (mode))
5778 || GET_CODE (op0) != REG || op1 == 0)
5781 /* Put OP0 in the hash table if it isn't already. This gives it a
5782 new quantity number. */
5785 if (insert_regs (op0, NULL_PTR, 0))
5787 rehash_using_reg (op0);
5788 op0_hash = HASH (op0, mode);
5790 /* If OP0 is contained in OP1, this changes its hash code
5791 as well. Faster to rehash than to check, except
5792 for the simple case of a constant. */
5793 if (! CONSTANT_P (op1))
5794 op1_hash = HASH (op1,mode);
5797 op0_elt = insert (op0, NULL_PTR, op0_hash, mode);
5798 op0_elt->in_memory = op0_in_memory;
5799 op0_elt->in_struct = op0_in_struct;
5802 qty_comparison_code[reg_qty[REGNO (op0)]] = code;
5803 if (GET_CODE (op1) == REG)
5805 /* Look it up again--in case op0 and op1 are the same. */
5806 op1_elt = lookup (op1, op1_hash, mode);
5808 /* Put OP1 in the hash table so it gets a new quantity number. */
5811 if (insert_regs (op1, NULL_PTR, 0))
5813 rehash_using_reg (op1);
5814 op1_hash = HASH (op1, mode);
5817 op1_elt = insert (op1, NULL_PTR, op1_hash, mode);
5818 op1_elt->in_memory = op1_in_memory;
5819 op1_elt->in_struct = op1_in_struct;
5822 qty_comparison_qty[reg_qty[REGNO (op0)]] = reg_qty[REGNO (op1)];
5823 qty_comparison_const[reg_qty[REGNO (op0)]] = 0;
5827 qty_comparison_qty[reg_qty[REGNO (op0)]] = -1;
5828 qty_comparison_const[reg_qty[REGNO (op0)]] = op1;
5834 /* If either side is still missing an equivalence, make it now,
5835 then merge the equivalences. */
5839 if (insert_regs (op0, NULL_PTR, 0))
5841 rehash_using_reg (op0);
5842 op0_hash = HASH (op0, mode);
5845 op0_elt = insert (op0, NULL_PTR, op0_hash, mode);
5846 op0_elt->in_memory = op0_in_memory;
5847 op0_elt->in_struct = op0_in_struct;
5852 if (insert_regs (op1, NULL_PTR, 0))
5854 rehash_using_reg (op1);
5855 op1_hash = HASH (op1, mode);
5858 op1_elt = insert (op1, NULL_PTR, op1_hash, mode);
5859 op1_elt->in_memory = op1_in_memory;
5860 op1_elt->in_struct = op1_in_struct;
5863 merge_equiv_classes (op0_elt, op1_elt);
5864 last_jump_equiv_class = op0_elt;
5867 /* CSE processing for one instruction.
5868 First simplify sources and addresses of all assignments
5869 in the instruction, using previously-computed equivalents values.
5870 Then install the new sources and destinations in the table
5871 of available values.
5873 If IN_LIBCALL_BLOCK is nonzero, don't record any equivalence made in
5876 /* Data on one SET contained in the instruction. */
5880 /* The SET rtx itself. */
5882 /* The SET_SRC of the rtx (the original value, if it is changing). */
5884 /* The hash-table element for the SET_SRC of the SET. */
5885 struct table_elt *src_elt;
5886 /* Hash value for the SET_SRC. */
5888 /* Hash value for the SET_DEST. */
5890 /* The SET_DEST, with SUBREG, etc., stripped. */
5892 /* Place where the pointer to the INNER_DEST was found. */
5893 rtx *inner_dest_loc;
5894 /* Nonzero if the SET_SRC is in memory. */
5896 /* Nonzero if the SET_SRC is in a structure. */
5898 /* Nonzero if the SET_SRC contains something
5899 whose value cannot be predicted and understood. */
5901 /* Original machine mode, in case it becomes a CONST_INT. */
5902 enum machine_mode mode;
5903 /* A constant equivalent for SET_SRC, if any. */
5905 /* Hash value of constant equivalent for SET_SRC. */
5906 unsigned src_const_hash;
5907 /* Table entry for constant equivalent for SET_SRC, if any. */
5908 struct table_elt *src_const_elt;
5912 cse_insn (insn, in_libcall_block)
5914 int in_libcall_block;
5916 register rtx x = PATTERN (insn);
5919 register int n_sets = 0;
5921 /* Records what this insn does to set CC0. */
5922 rtx this_insn_cc0 = 0;
5923 enum machine_mode this_insn_cc0_mode;
5924 struct write_data writes_memory;
5925 static struct write_data init = {0, 0, 0, 0};
5928 struct table_elt *src_eqv_elt = 0;
5929 int src_eqv_volatile;
5930 int src_eqv_in_memory;
5931 int src_eqv_in_struct;
5932 unsigned src_eqv_hash;
5937 writes_memory = init;
5939 /* Find all the SETs and CLOBBERs in this instruction.
5940 Record all the SETs in the array `set' and count them.
5941 Also determine whether there is a CLOBBER that invalidates
5942 all memory references, or all references at varying addresses. */
5944 if (GET_CODE (insn) == CALL_INSN)
5946 for (tem = CALL_INSN_FUNCTION_USAGE (insn); tem; tem = XEXP (tem, 1))
5947 if (GET_CODE (XEXP (tem, 0)) == CLOBBER)
5948 invalidate (SET_DEST (XEXP (tem, 0)));
5951 if (GET_CODE (x) == SET)
5953 sets = (struct set *) alloca (sizeof (struct set));
5956 /* Ignore SETs that are unconditional jumps.
5957 They never need cse processing, so this does not hurt.
5958 The reason is not efficiency but rather
5959 so that we can test at the end for instructions
5960 that have been simplified to unconditional jumps
5961 and not be misled by unchanged instructions
5962 that were unconditional jumps to begin with. */
5963 if (SET_DEST (x) == pc_rtx
5964 && GET_CODE (SET_SRC (x)) == LABEL_REF)
5967 /* Don't count call-insns, (set (reg 0) (call ...)), as a set.
5968 The hard function value register is used only once, to copy to
5969 someplace else, so it isn't worth cse'ing (and on 80386 is unsafe)!
5970 Ensure we invalidate the destination register. On the 80386 no
5971 other code would invalidate it since it is a fixed_reg.
5972 We need not check the return of apply_change_group; see canon_reg. */
5974 else if (GET_CODE (SET_SRC (x)) == CALL)
5976 canon_reg (SET_SRC (x), insn);
5977 apply_change_group ();
5978 fold_rtx (SET_SRC (x), insn);
5979 invalidate (SET_DEST (x));
5984 else if (GET_CODE (x) == PARALLEL)
5986 register int lim = XVECLEN (x, 0);
5988 sets = (struct set *) alloca (lim * sizeof (struct set));
5990 /* Find all regs explicitly clobbered in this insn,
5991 and ensure they are not replaced with any other regs
5992 elsewhere in this insn.
5993 When a reg that is clobbered is also used for input,
5994 we should presume that that is for a reason,
5995 and we should not substitute some other register
5996 which is not supposed to be clobbered.
5997 Therefore, this loop cannot be merged into the one below
5998 because a CALL may precede a CLOBBER and refer to the
5999 value clobbered. We must not let a canonicalization do
6000 anything in that case. */
6001 for (i = 0; i < lim; i++)
6003 register rtx y = XVECEXP (x, 0, i);
6004 if (GET_CODE (y) == CLOBBER)
6006 rtx clobbered = XEXP (y, 0);
6008 if (GET_CODE (clobbered) == REG
6009 || GET_CODE (clobbered) == SUBREG)
6010 invalidate (clobbered);
6011 else if (GET_CODE (clobbered) == STRICT_LOW_PART
6012 || GET_CODE (clobbered) == ZERO_EXTRACT)
6013 invalidate (XEXP (clobbered, 0));
6017 for (i = 0; i < lim; i++)
6019 register rtx y = XVECEXP (x, 0, i);
6020 if (GET_CODE (y) == SET)
6022 /* As above, we ignore unconditional jumps and call-insns and
6023 ignore the result of apply_change_group. */
6024 if (GET_CODE (SET_SRC (y)) == CALL)
6026 canon_reg (SET_SRC (y), insn);
6027 apply_change_group ();
6028 fold_rtx (SET_SRC (y), insn);
6029 invalidate (SET_DEST (y));
6031 else if (SET_DEST (y) == pc_rtx
6032 && GET_CODE (SET_SRC (y)) == LABEL_REF)
6035 sets[n_sets++].rtl = y;
6037 else if (GET_CODE (y) == CLOBBER)
6039 /* If we clobber memory, take note of that,
6040 and canon the address.
6041 This does nothing when a register is clobbered
6042 because we have already invalidated the reg. */
6043 if (GET_CODE (XEXP (y, 0)) == MEM)
6045 canon_reg (XEXP (y, 0), NULL_RTX);
6046 note_mem_written (XEXP (y, 0), &writes_memory);
6049 else if (GET_CODE (y) == USE
6050 && ! (GET_CODE (XEXP (y, 0)) == REG
6051 && REGNO (XEXP (y, 0)) < FIRST_PSEUDO_REGISTER))
6052 canon_reg (y, NULL_RTX);
6053 else if (GET_CODE (y) == CALL)
6055 /* The result of apply_change_group can be ignored; see
6057 canon_reg (y, insn);
6058 apply_change_group ();
6063 else if (GET_CODE (x) == CLOBBER)
6065 if (GET_CODE (XEXP (x, 0)) == MEM)
6067 canon_reg (XEXP (x, 0), NULL_RTX);
6068 note_mem_written (XEXP (x, 0), &writes_memory);
6072 /* Canonicalize a USE of a pseudo register or memory location. */
6073 else if (GET_CODE (x) == USE
6074 && ! (GET_CODE (XEXP (x, 0)) == REG
6075 && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER))
6076 canon_reg (XEXP (x, 0), NULL_RTX);
6077 else if (GET_CODE (x) == CALL)
6079 /* The result of apply_change_group can be ignored; see canon_reg. */
6080 canon_reg (x, insn);
6081 apply_change_group ();
6085 /* Store the equivalent value in SRC_EQV, if different, or if the DEST
6086 is a STRICT_LOW_PART. The latter condition is necessary because SRC_EQV
6087 is handled specially for this case, and if it isn't set, then there will
6088 be no equivalence for the destinatation. */
6089 if (n_sets == 1 && REG_NOTES (insn) != 0
6090 && (tem = find_reg_note (insn, REG_EQUAL, NULL_RTX)) != 0
6091 && (! rtx_equal_p (XEXP (tem, 0), SET_SRC (sets[0].rtl))
6092 || GET_CODE (SET_DEST (sets[0].rtl)) == STRICT_LOW_PART))
6093 src_eqv = canon_reg (XEXP (tem, 0), NULL_RTX);
6095 /* Canonicalize sources and addresses of destinations.
6096 We do this in a separate pass to avoid problems when a MATCH_DUP is
6097 present in the insn pattern. In that case, we want to ensure that
6098 we don't break the duplicate nature of the pattern. So we will replace
6099 both operands at the same time. Otherwise, we would fail to find an
6100 equivalent substitution in the loop calling validate_change below.
6102 We used to suppress canonicalization of DEST if it appears in SRC,
6103 but we don't do this any more. */
6105 for (i = 0; i < n_sets; i++)
6107 rtx dest = SET_DEST (sets[i].rtl);
6108 rtx src = SET_SRC (sets[i].rtl);
6109 rtx new = canon_reg (src, insn);
6111 if ((GET_CODE (new) == REG && GET_CODE (src) == REG
6112 && ((REGNO (new) < FIRST_PSEUDO_REGISTER)
6113 != (REGNO (src) < FIRST_PSEUDO_REGISTER)))
6114 || insn_n_dups[recog_memoized (insn)] > 0)
6115 validate_change (insn, &SET_SRC (sets[i].rtl), new, 1);
6117 SET_SRC (sets[i].rtl) = new;
6119 if (GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SIGN_EXTRACT)
6121 validate_change (insn, &XEXP (dest, 1),
6122 canon_reg (XEXP (dest, 1), insn), 1);
6123 validate_change (insn, &XEXP (dest, 2),
6124 canon_reg (XEXP (dest, 2), insn), 1);
6127 while (GET_CODE (dest) == SUBREG || GET_CODE (dest) == STRICT_LOW_PART
6128 || GET_CODE (dest) == ZERO_EXTRACT
6129 || GET_CODE (dest) == SIGN_EXTRACT)
6130 dest = XEXP (dest, 0);
6132 if (GET_CODE (dest) == MEM)
6133 canon_reg (dest, insn);
6136 /* Now that we have done all the replacements, we can apply the change
6137 group and see if they all work. Note that this will cause some
6138 canonicalizations that would have worked individually not to be applied
6139 because some other canonicalization didn't work, but this should not
6142 The result of apply_change_group can be ignored; see canon_reg. */
6144 apply_change_group ();
6146 /* Set sets[i].src_elt to the class each source belongs to.
6147 Detect assignments from or to volatile things
6148 and set set[i] to zero so they will be ignored
6149 in the rest of this function.
6151 Nothing in this loop changes the hash table or the register chains. */
6153 for (i = 0; i < n_sets; i++)
6155 register rtx src, dest;
6156 register rtx src_folded;
6157 register struct table_elt *elt = 0, *p;
6158 enum machine_mode mode;
6161 rtx src_related = 0;
6162 struct table_elt *src_const_elt = 0;
6163 int src_cost = 10000, src_eqv_cost = 10000, src_folded_cost = 10000;
6164 int src_related_cost = 10000, src_elt_cost = 10000;
6165 /* Set non-zero if we need to call force_const_mem on with the
6166 contents of src_folded before using it. */
6167 int src_folded_force_flag = 0;
6169 dest = SET_DEST (sets[i].rtl);
6170 src = SET_SRC (sets[i].rtl);
6172 /* If SRC is a constant that has no machine mode,
6173 hash it with the destination's machine mode.
6174 This way we can keep different modes separate. */
6176 mode = GET_MODE (src) == VOIDmode ? GET_MODE (dest) : GET_MODE (src);
6177 sets[i].mode = mode;
6181 enum machine_mode eqvmode = mode;
6182 if (GET_CODE (dest) == STRICT_LOW_PART)
6183 eqvmode = GET_MODE (SUBREG_REG (XEXP (dest, 0)));
6185 hash_arg_in_memory = 0;
6186 hash_arg_in_struct = 0;
6187 src_eqv = fold_rtx (src_eqv, insn);
6188 src_eqv_hash = HASH (src_eqv, eqvmode);
6190 /* Find the equivalence class for the equivalent expression. */
6193 src_eqv_elt = lookup (src_eqv, src_eqv_hash, eqvmode);
6195 src_eqv_volatile = do_not_record;
6196 src_eqv_in_memory = hash_arg_in_memory;
6197 src_eqv_in_struct = hash_arg_in_struct;
6200 /* If this is a STRICT_LOW_PART assignment, src_eqv corresponds to the
6201 value of the INNER register, not the destination. So it is not
6202 a legal substitution for the source. But save it for later. */
6203 if (GET_CODE (dest) == STRICT_LOW_PART)
6206 src_eqv_here = src_eqv;
6208 /* Simplify and foldable subexpressions in SRC. Then get the fully-
6209 simplified result, which may not necessarily be valid. */
6210 src_folded = fold_rtx (src, insn);
6212 /* If storing a constant in a bitfield, pre-truncate the constant
6213 so we will be able to record it later. */
6214 if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT
6215 || GET_CODE (SET_DEST (sets[i].rtl)) == SIGN_EXTRACT)
6217 rtx width = XEXP (SET_DEST (sets[i].rtl), 1);
6219 if (GET_CODE (src) == CONST_INT
6220 && GET_CODE (width) == CONST_INT
6221 && INTVAL (width) < HOST_BITS_PER_WIDE_INT
6222 && (INTVAL (src) & ((HOST_WIDE_INT) (-1) << INTVAL (width))))
6224 = GEN_INT (INTVAL (src) & (((HOST_WIDE_INT) 1
6225 << INTVAL (width)) - 1));
6228 /* Compute SRC's hash code, and also notice if it
6229 should not be recorded at all. In that case,
6230 prevent any further processing of this assignment. */
6232 hash_arg_in_memory = 0;
6233 hash_arg_in_struct = 0;
6236 sets[i].src_hash = HASH (src, mode);
6237 sets[i].src_volatile = do_not_record;
6238 sets[i].src_in_memory = hash_arg_in_memory;
6239 sets[i].src_in_struct = hash_arg_in_struct;
6242 /* It is no longer clear why we used to do this, but it doesn't
6243 appear to still be needed. So let's try without it since this
6244 code hurts cse'ing widened ops. */
6245 /* If source is a perverse subreg (such as QI treated as an SI),
6246 treat it as volatile. It may do the work of an SI in one context
6247 where the extra bits are not being used, but cannot replace an SI
6249 if (GET_CODE (src) == SUBREG
6250 && (GET_MODE_SIZE (GET_MODE (src))
6251 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (src)))))
6252 sets[i].src_volatile = 1;
6255 /* Locate all possible equivalent forms for SRC. Try to replace
6256 SRC in the insn with each cheaper equivalent.
6258 We have the following types of equivalents: SRC itself, a folded
6259 version, a value given in a REG_EQUAL note, or a value related
6262 Each of these equivalents may be part of an additional class
6263 of equivalents (if more than one is in the table, they must be in
6264 the same class; we check for this).
6266 If the source is volatile, we don't do any table lookups.
6268 We note any constant equivalent for possible later use in a
6271 if (!sets[i].src_volatile)
6272 elt = lookup (src, sets[i].src_hash, mode);
6274 sets[i].src_elt = elt;
6276 if (elt && src_eqv_here && src_eqv_elt)
6278 if (elt->first_same_value != src_eqv_elt->first_same_value)
6280 /* The REG_EQUAL is indicating that two formerly distinct
6281 classes are now equivalent. So merge them. */
6282 merge_equiv_classes (elt, src_eqv_elt);
6283 src_eqv_hash = HASH (src_eqv, elt->mode);
6284 src_eqv_elt = lookup (src_eqv, src_eqv_hash, elt->mode);
6290 else if (src_eqv_elt)
6293 /* Try to find a constant somewhere and record it in `src_const'.
6294 Record its table element, if any, in `src_const_elt'. Look in
6295 any known equivalences first. (If the constant is not in the
6296 table, also set `sets[i].src_const_hash'). */
6298 for (p = elt->first_same_value; p; p = p->next_same_value)
6302 src_const_elt = elt;
6307 && (CONSTANT_P (src_folded)
6308 /* Consider (minus (label_ref L1) (label_ref L2)) as
6309 "constant" here so we will record it. This allows us
6310 to fold switch statements when an ADDR_DIFF_VEC is used. */
6311 || (GET_CODE (src_folded) == MINUS
6312 && GET_CODE (XEXP (src_folded, 0)) == LABEL_REF
6313 && GET_CODE (XEXP (src_folded, 1)) == LABEL_REF)))
6314 src_const = src_folded, src_const_elt = elt;
6315 else if (src_const == 0 && src_eqv_here && CONSTANT_P (src_eqv_here))
6316 src_const = src_eqv_here, src_const_elt = src_eqv_elt;
6318 /* If we don't know if the constant is in the table, get its
6319 hash code and look it up. */
6320 if (src_const && src_const_elt == 0)
6322 sets[i].src_const_hash = HASH (src_const, mode);
6323 src_const_elt = lookup (src_const, sets[i].src_const_hash, mode);
6326 sets[i].src_const = src_const;
6327 sets[i].src_const_elt = src_const_elt;
6329 /* If the constant and our source are both in the table, mark them as
6330 equivalent. Otherwise, if a constant is in the table but the source
6331 isn't, set ELT to it. */
6332 if (src_const_elt && elt
6333 && src_const_elt->first_same_value != elt->first_same_value)
6334 merge_equiv_classes (elt, src_const_elt);
6335 else if (src_const_elt && elt == 0)
6336 elt = src_const_elt;
6338 /* See if there is a register linearly related to a constant
6339 equivalent of SRC. */
6341 && (GET_CODE (src_const) == CONST
6342 || (src_const_elt && src_const_elt->related_value != 0)))
6344 src_related = use_related_value (src_const, src_const_elt);
6347 struct table_elt *src_related_elt
6348 = lookup (src_related, HASH (src_related, mode), mode);
6349 if (src_related_elt && elt)
6351 if (elt->first_same_value
6352 != src_related_elt->first_same_value)
6353 /* This can occur when we previously saw a CONST
6354 involving a SYMBOL_REF and then see the SYMBOL_REF
6355 twice. Merge the involved classes. */
6356 merge_equiv_classes (elt, src_related_elt);
6359 src_related_elt = 0;
6361 else if (src_related_elt && elt == 0)
6362 elt = src_related_elt;
6366 /* See if we have a CONST_INT that is already in a register in a
6369 if (src_const && src_related == 0 && GET_CODE (src_const) == CONST_INT
6370 && GET_MODE_CLASS (mode) == MODE_INT
6371 && GET_MODE_BITSIZE (mode) < BITS_PER_WORD)
6373 enum machine_mode wider_mode;
6375 for (wider_mode = GET_MODE_WIDER_MODE (mode);
6376 GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD
6377 && src_related == 0;
6378 wider_mode = GET_MODE_WIDER_MODE (wider_mode))
6380 struct table_elt *const_elt
6381 = lookup (src_const, HASH (src_const, wider_mode), wider_mode);
6386 for (const_elt = const_elt->first_same_value;
6387 const_elt; const_elt = const_elt->next_same_value)
6388 if (GET_CODE (const_elt->exp) == REG)
6390 src_related = gen_lowpart_if_possible (mode,
6397 /* Another possibility is that we have an AND with a constant in
6398 a mode narrower than a word. If so, it might have been generated
6399 as part of an "if" which would narrow the AND. If we already
6400 have done the AND in a wider mode, we can use a SUBREG of that
6403 if (flag_expensive_optimizations && ! src_related
6404 && GET_CODE (src) == AND && GET_CODE (XEXP (src, 1)) == CONST_INT
6405 && GET_MODE_SIZE (mode) < UNITS_PER_WORD)
6407 enum machine_mode tmode;
6408 rtx new_and = gen_rtx (AND, VOIDmode, NULL_RTX, XEXP (src, 1));
6410 for (tmode = GET_MODE_WIDER_MODE (mode);
6411 GET_MODE_SIZE (tmode) <= UNITS_PER_WORD;
6412 tmode = GET_MODE_WIDER_MODE (tmode))
6414 rtx inner = gen_lowpart_if_possible (tmode, XEXP (src, 0));
6415 struct table_elt *larger_elt;
6419 PUT_MODE (new_and, tmode);
6420 XEXP (new_and, 0) = inner;
6421 larger_elt = lookup (new_and, HASH (new_and, tmode), tmode);
6422 if (larger_elt == 0)
6425 for (larger_elt = larger_elt->first_same_value;
6426 larger_elt; larger_elt = larger_elt->next_same_value)
6427 if (GET_CODE (larger_elt->exp) == REG)
6430 = gen_lowpart_if_possible (mode, larger_elt->exp);
6440 #ifdef LOAD_EXTEND_OP
6441 /* See if a MEM has already been loaded with a widening operation;
6442 if it has, we can use a subreg of that. Many CISC machines
6443 also have such operations, but this is only likely to be
6444 beneficial these machines. */
6446 if (flag_expensive_optimizations && src_related == 0
6447 && (GET_MODE_SIZE (mode) < UNITS_PER_WORD)
6448 && GET_MODE_CLASS (mode) == MODE_INT
6449 && GET_CODE (src) == MEM && ! do_not_record
6450 && LOAD_EXTEND_OP (mode) != NIL)
6452 enum machine_mode tmode;
6454 /* Set what we are trying to extend and the operation it might
6455 have been extended with. */
6456 PUT_CODE (memory_extend_rtx, LOAD_EXTEND_OP (mode));
6457 XEXP (memory_extend_rtx, 0) = src;
6459 for (tmode = GET_MODE_WIDER_MODE (mode);
6460 GET_MODE_SIZE (tmode) <= UNITS_PER_WORD;
6461 tmode = GET_MODE_WIDER_MODE (tmode))
6463 struct table_elt *larger_elt;
6465 PUT_MODE (memory_extend_rtx, tmode);
6466 larger_elt = lookup (memory_extend_rtx,
6467 HASH (memory_extend_rtx, tmode), tmode);
6468 if (larger_elt == 0)
6471 for (larger_elt = larger_elt->first_same_value;
6472 larger_elt; larger_elt = larger_elt->next_same_value)
6473 if (GET_CODE (larger_elt->exp) == REG)
6475 src_related = gen_lowpart_if_possible (mode,
6484 #endif /* LOAD_EXTEND_OP */
6486 if (src == src_folded)
6489 /* At this point, ELT, if non-zero, points to a class of expressions
6490 equivalent to the source of this SET and SRC, SRC_EQV, SRC_FOLDED,
6491 and SRC_RELATED, if non-zero, each contain additional equivalent
6492 expressions. Prune these latter expressions by deleting expressions
6493 already in the equivalence class.
6495 Check for an equivalent identical to the destination. If found,
6496 this is the preferred equivalent since it will likely lead to
6497 elimination of the insn. Indicate this by placing it in
6500 if (elt) elt = elt->first_same_value;
6501 for (p = elt; p; p = p->next_same_value)
6503 enum rtx_code code = GET_CODE (p->exp);
6505 /* If the expression is not valid, ignore it. Then we do not
6506 have to check for validity below. In most cases, we can use
6507 `rtx_equal_p', since canonicalization has already been done. */
6508 if (code != REG && ! exp_equiv_p (p->exp, p->exp, 1, 0))
6511 if (src && GET_CODE (src) == code && rtx_equal_p (src, p->exp))
6513 else if (src_folded && GET_CODE (src_folded) == code
6514 && rtx_equal_p (src_folded, p->exp))
6516 else if (src_eqv_here && GET_CODE (src_eqv_here) == code
6517 && rtx_equal_p (src_eqv_here, p->exp))
6519 else if (src_related && GET_CODE (src_related) == code
6520 && rtx_equal_p (src_related, p->exp))
6523 /* This is the same as the destination of the insns, we want
6524 to prefer it. Copy it to src_related. The code below will
6525 then give it a negative cost. */
6526 if (GET_CODE (dest) == code && rtx_equal_p (p->exp, dest))
6531 /* Find the cheapest valid equivalent, trying all the available
6532 possibilities. Prefer items not in the hash table to ones
6533 that are when they are equal cost. Note that we can never
6534 worsen an insn as the current contents will also succeed.
6535 If we find an equivalent identical to the destination, use it as best,
6536 since this insn will probably be eliminated in that case. */
6539 if (rtx_equal_p (src, dest))
6542 src_cost = COST (src);
6547 if (rtx_equal_p (src_eqv_here, dest))
6550 src_eqv_cost = COST (src_eqv_here);
6555 if (rtx_equal_p (src_folded, dest))
6556 src_folded_cost = -1;
6558 src_folded_cost = COST (src_folded);
6563 if (rtx_equal_p (src_related, dest))
6564 src_related_cost = -1;
6566 src_related_cost = COST (src_related);
6569 /* If this was an indirect jump insn, a known label will really be
6570 cheaper even though it looks more expensive. */
6571 if (dest == pc_rtx && src_const && GET_CODE (src_const) == LABEL_REF)
6572 src_folded = src_const, src_folded_cost = -1;
6574 /* Terminate loop when replacement made. This must terminate since
6575 the current contents will be tested and will always be valid. */
6580 /* Skip invalid entries. */
6581 while (elt && GET_CODE (elt->exp) != REG
6582 && ! exp_equiv_p (elt->exp, elt->exp, 1, 0))
6583 elt = elt->next_same_value;
6585 if (elt) src_elt_cost = elt->cost;
6587 /* Find cheapest and skip it for the next time. For items
6588 of equal cost, use this order:
6589 src_folded, src, src_eqv, src_related and hash table entry. */
6590 if (src_folded_cost <= src_cost
6591 && src_folded_cost <= src_eqv_cost
6592 && src_folded_cost <= src_related_cost
6593 && src_folded_cost <= src_elt_cost)
6595 trial = src_folded, src_folded_cost = 10000;
6596 if (src_folded_force_flag)
6597 trial = force_const_mem (mode, trial);
6599 else if (src_cost <= src_eqv_cost
6600 && src_cost <= src_related_cost
6601 && src_cost <= src_elt_cost)
6602 trial = src, src_cost = 10000;
6603 else if (src_eqv_cost <= src_related_cost
6604 && src_eqv_cost <= src_elt_cost)
6605 trial = copy_rtx (src_eqv_here), src_eqv_cost = 10000;
6606 else if (src_related_cost <= src_elt_cost)
6607 trial = copy_rtx (src_related), src_related_cost = 10000;
6610 trial = copy_rtx (elt->exp);
6611 elt = elt->next_same_value;
6612 src_elt_cost = 10000;
6615 /* We don't normally have an insn matching (set (pc) (pc)), so
6616 check for this separately here. We will delete such an
6619 Tablejump insns contain a USE of the table, so simply replacing
6620 the operand with the constant won't match. This is simply an
6621 unconditional branch, however, and is therefore valid. Just
6622 insert the substitution here and we will delete and re-emit
6625 if (n_sets == 1 && dest == pc_rtx
6627 || (GET_CODE (trial) == LABEL_REF
6628 && ! condjump_p (insn))))
6630 /* If TRIAL is a label in front of a jump table, we are
6631 really falling through the switch (this is how casesi
6632 insns work), so we must branch around the table. */
6633 if (GET_CODE (trial) == CODE_LABEL
6634 && NEXT_INSN (trial) != 0
6635 && GET_CODE (NEXT_INSN (trial)) == JUMP_INSN
6636 && (GET_CODE (PATTERN (NEXT_INSN (trial))) == ADDR_DIFF_VEC
6637 || GET_CODE (PATTERN (NEXT_INSN (trial))) == ADDR_VEC))
6639 trial = gen_rtx (LABEL_REF, Pmode, get_label_after (trial));
6641 SET_SRC (sets[i].rtl) = trial;
6642 cse_jumps_altered = 1;
6646 /* Look for a substitution that makes a valid insn. */
6647 else if (validate_change (insn, &SET_SRC (sets[i].rtl), trial, 0))
6649 /* The result of apply_change_group can be ignored; see
6652 validate_change (insn, &SET_SRC (sets[i].rtl),
6653 canon_reg (SET_SRC (sets[i].rtl), insn),
6655 apply_change_group ();
6659 /* If we previously found constant pool entries for
6660 constants and this is a constant, try making a
6661 pool entry. Put it in src_folded unless we already have done
6662 this since that is where it likely came from. */
6664 else if (constant_pool_entries_cost
6665 && CONSTANT_P (trial)
6666 && (src_folded == 0 || GET_CODE (src_folded) != MEM)
6667 && GET_MODE_CLASS (mode) != MODE_CC)
6669 src_folded_force_flag = 1;
6671 src_folded_cost = constant_pool_entries_cost;
6675 src = SET_SRC (sets[i].rtl);
6677 /* In general, it is good to have a SET with SET_SRC == SET_DEST.
6678 However, there is an important exception: If both are registers
6679 that are not the head of their equivalence class, replace SET_SRC
6680 with the head of the class. If we do not do this, we will have
6681 both registers live over a portion of the basic block. This way,
6682 their lifetimes will likely abut instead of overlapping. */
6683 if (GET_CODE (dest) == REG
6684 && REGNO_QTY_VALID_P (REGNO (dest))
6685 && qty_mode[reg_qty[REGNO (dest)]] == GET_MODE (dest)
6686 && qty_first_reg[reg_qty[REGNO (dest)]] != REGNO (dest)
6687 && GET_CODE (src) == REG && REGNO (src) == REGNO (dest)
6688 /* Don't do this if the original insn had a hard reg as
6690 && (GET_CODE (sets[i].src) != REG
6691 || REGNO (sets[i].src) >= FIRST_PSEUDO_REGISTER))
6692 /* We can't call canon_reg here because it won't do anything if
6693 SRC is a hard register. */
6695 int first = qty_first_reg[reg_qty[REGNO (src)]];
6697 src = SET_SRC (sets[i].rtl)
6698 = first >= FIRST_PSEUDO_REGISTER ? regno_reg_rtx[first]
6699 : gen_rtx (REG, GET_MODE (src), first);
6701 /* If we had a constant that is cheaper than what we are now
6702 setting SRC to, use that constant. We ignored it when we
6703 thought we could make this into a no-op. */
6704 if (src_const && COST (src_const) < COST (src)
6705 && validate_change (insn, &SET_SRC (sets[i].rtl), src_const, 0))
6709 /* If we made a change, recompute SRC values. */
6710 if (src != sets[i].src)
6713 hash_arg_in_memory = 0;
6714 hash_arg_in_struct = 0;
6716 sets[i].src_hash = HASH (src, mode);
6717 sets[i].src_volatile = do_not_record;
6718 sets[i].src_in_memory = hash_arg_in_memory;
6719 sets[i].src_in_struct = hash_arg_in_struct;
6720 sets[i].src_elt = lookup (src, sets[i].src_hash, mode);
6723 /* If this is a single SET, we are setting a register, and we have an
6724 equivalent constant, we want to add a REG_NOTE. We don't want
6725 to write a REG_EQUAL note for a constant pseudo since verifying that
6726 that pseudo hasn't been eliminated is a pain. Such a note also
6727 won't help anything. */
6728 if (n_sets == 1 && src_const && GET_CODE (dest) == REG
6729 && GET_CODE (src_const) != REG)
6731 tem = find_reg_note (insn, REG_EQUAL, NULL_RTX);
6733 /* Record the actual constant value in a REG_EQUAL note, making
6734 a new one if one does not already exist. */
6736 XEXP (tem, 0) = src_const;
6738 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_EQUAL,
6739 src_const, REG_NOTES (insn));
6741 /* If storing a constant value in a register that
6742 previously held the constant value 0,
6743 record this fact with a REG_WAS_0 note on this insn.
6745 Note that the *register* is required to have previously held 0,
6746 not just any register in the quantity and we must point to the
6747 insn that set that register to zero.
6749 Rather than track each register individually, we just see if
6750 the last set for this quantity was for this register. */
6752 if (REGNO_QTY_VALID_P (REGNO (dest))
6753 && qty_const[reg_qty[REGNO (dest)]] == const0_rtx)
6755 /* See if we previously had a REG_WAS_0 note. */
6756 rtx note = find_reg_note (insn, REG_WAS_0, NULL_RTX);
6757 rtx const_insn = qty_const_insn[reg_qty[REGNO (dest)]];
6759 if ((tem = single_set (const_insn)) != 0
6760 && rtx_equal_p (SET_DEST (tem), dest))
6763 XEXP (note, 0) = const_insn;
6765 REG_NOTES (insn) = gen_rtx (INSN_LIST, REG_WAS_0,
6766 const_insn, REG_NOTES (insn));
6771 /* Now deal with the destination. */
6773 sets[i].inner_dest_loc = &SET_DEST (sets[0].rtl);
6775 /* Look within any SIGN_EXTRACT or ZERO_EXTRACT
6776 to the MEM or REG within it. */
6777 while (GET_CODE (dest) == SIGN_EXTRACT
6778 || GET_CODE (dest) == ZERO_EXTRACT
6779 || GET_CODE (dest) == SUBREG
6780 || GET_CODE (dest) == STRICT_LOW_PART)
6782 sets[i].inner_dest_loc = &XEXP (dest, 0);
6783 dest = XEXP (dest, 0);
6786 sets[i].inner_dest = dest;
6788 if (GET_CODE (dest) == MEM)
6790 dest = fold_rtx (dest, insn);
6792 /* Decide whether we invalidate everything in memory,
6793 or just things at non-fixed places.
6794 Writing a large aggregate must invalidate everything
6795 because we don't know how long it is. */
6796 note_mem_written (dest, &writes_memory);
6799 /* Compute the hash code of the destination now,
6800 before the effects of this instruction are recorded,
6801 since the register values used in the address computation
6802 are those before this instruction. */
6803 sets[i].dest_hash = HASH (dest, mode);
6805 /* Don't enter a bit-field in the hash table
6806 because the value in it after the store
6807 may not equal what was stored, due to truncation. */
6809 if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT
6810 || GET_CODE (SET_DEST (sets[i].rtl)) == SIGN_EXTRACT)
6812 rtx width = XEXP (SET_DEST (sets[i].rtl), 1);
6814 if (src_const != 0 && GET_CODE (src_const) == CONST_INT
6815 && GET_CODE (width) == CONST_INT
6816 && INTVAL (width) < HOST_BITS_PER_WIDE_INT
6817 && ! (INTVAL (src_const)
6818 & ((HOST_WIDE_INT) (-1) << INTVAL (width))))
6819 /* Exception: if the value is constant,
6820 and it won't be truncated, record it. */
6824 /* This is chosen so that the destination will be invalidated
6825 but no new value will be recorded.
6826 We must invalidate because sometimes constant
6827 values can be recorded for bitfields. */
6828 sets[i].src_elt = 0;
6829 sets[i].src_volatile = 1;
6835 /* If only one set in a JUMP_INSN and it is now a no-op, we can delete
6837 else if (n_sets == 1 && dest == pc_rtx && src == pc_rtx)
6839 PUT_CODE (insn, NOTE);
6840 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
6841 NOTE_SOURCE_FILE (insn) = 0;
6842 cse_jumps_altered = 1;
6843 /* One less use of the label this insn used to jump to. */
6844 --LABEL_NUSES (JUMP_LABEL (insn));
6845 /* No more processing for this set. */
6849 /* If this SET is now setting PC to a label, we know it used to
6850 be a conditional or computed branch. So we see if we can follow
6851 it. If it was a computed branch, delete it and re-emit. */
6852 else if (dest == pc_rtx && GET_CODE (src) == LABEL_REF)
6856 /* If this is not in the format for a simple branch and
6857 we are the only SET in it, re-emit it. */
6858 if (! simplejump_p (insn) && n_sets == 1)
6860 rtx new = emit_jump_insn_before (gen_jump (XEXP (src, 0)), insn);
6861 JUMP_LABEL (new) = XEXP (src, 0);
6862 LABEL_NUSES (XEXP (src, 0))++;
6867 /* Otherwise, force rerecognition, since it probably had
6868 a different pattern before.
6869 This shouldn't really be necessary, since whatever
6870 changed the source value above should have done this.
6871 Until the right place is found, might as well do this here. */
6872 INSN_CODE (insn) = -1;
6874 /* Now that we've converted this jump to an unconditional jump,
6875 there is dead code after it. Delete the dead code until we
6876 reach a BARRIER, the end of the function, or a label. Do
6877 not delete NOTEs except for NOTE_INSN_DELETED since later
6878 phases assume these notes are retained. */
6882 while (NEXT_INSN (p) != 0
6883 && GET_CODE (NEXT_INSN (p)) != BARRIER
6884 && GET_CODE (NEXT_INSN (p)) != CODE_LABEL)
6886 if (GET_CODE (NEXT_INSN (p)) != NOTE
6887 || NOTE_LINE_NUMBER (NEXT_INSN (p)) == NOTE_INSN_DELETED)
6888 delete_insn (NEXT_INSN (p));
6893 /* If we don't have a BARRIER immediately after INSN, put one there.
6894 Much code assumes that there are no NOTEs between a JUMP_INSN and
6897 if (NEXT_INSN (insn) == 0
6898 || GET_CODE (NEXT_INSN (insn)) != BARRIER)
6899 emit_barrier_after (insn);
6901 /* We might have two BARRIERs separated by notes. Delete the second
6904 if (p != insn && NEXT_INSN (p) != 0
6905 && GET_CODE (NEXT_INSN (p)) == BARRIER)
6906 delete_insn (NEXT_INSN (p));
6908 cse_jumps_altered = 1;
6912 /* If destination is volatile, invalidate it and then do no further
6913 processing for this assignment. */
6915 else if (do_not_record)
6917 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG
6918 || GET_CODE (dest) == MEM)
6920 else if (GET_CODE (dest) == STRICT_LOW_PART
6921 || GET_CODE (dest) == ZERO_EXTRACT)
6922 invalidate (XEXP (dest, 0));
6926 if (sets[i].rtl != 0 && dest != SET_DEST (sets[i].rtl))
6927 sets[i].dest_hash = HASH (SET_DEST (sets[i].rtl), mode);
6930 /* If setting CC0, record what it was set to, or a constant, if it
6931 is equivalent to a constant. If it is being set to a floating-point
6932 value, make a COMPARE with the appropriate constant of 0. If we
6933 don't do this, later code can interpret this as a test against
6934 const0_rtx, which can cause problems if we try to put it into an
6935 insn as a floating-point operand. */
6936 if (dest == cc0_rtx)
6938 this_insn_cc0 = src_const && mode != VOIDmode ? src_const : src;
6939 this_insn_cc0_mode = mode;
6940 if (FLOAT_MODE_P (mode))
6941 this_insn_cc0 = gen_rtx (COMPARE, VOIDmode, this_insn_cc0,
6947 /* Now enter all non-volatile source expressions in the hash table
6948 if they are not already present.
6949 Record their equivalence classes in src_elt.
6950 This way we can insert the corresponding destinations into
6951 the same classes even if the actual sources are no longer in them
6952 (having been invalidated). */
6954 if (src_eqv && src_eqv_elt == 0 && sets[0].rtl != 0 && ! src_eqv_volatile
6955 && ! rtx_equal_p (src_eqv, SET_DEST (sets[0].rtl)))
6957 register struct table_elt *elt;
6958 register struct table_elt *classp = sets[0].src_elt;
6959 rtx dest = SET_DEST (sets[0].rtl);
6960 enum machine_mode eqvmode = GET_MODE (dest);
6962 if (GET_CODE (dest) == STRICT_LOW_PART)
6964 eqvmode = GET_MODE (SUBREG_REG (XEXP (dest, 0)));
6967 if (insert_regs (src_eqv, classp, 0))
6968 src_eqv_hash = HASH (src_eqv, eqvmode);
6969 elt = insert (src_eqv, classp, src_eqv_hash, eqvmode);
6970 elt->in_memory = src_eqv_in_memory;
6971 elt->in_struct = src_eqv_in_struct;
6974 /* Check to see if src_eqv_elt is the same as a set source which
6975 does not yet have an elt, and if so set the elt of the set source
6977 for (i = 0; i < n_sets; i++)
6978 if (sets[i].rtl && sets[i].src_elt == 0
6979 && rtx_equal_p (SET_SRC (sets[i].rtl), src_eqv))
6980 sets[i].src_elt = src_eqv_elt;
6983 for (i = 0; i < n_sets; i++)
6984 if (sets[i].rtl && ! sets[i].src_volatile
6985 && ! rtx_equal_p (SET_SRC (sets[i].rtl), SET_DEST (sets[i].rtl)))
6987 if (GET_CODE (SET_DEST (sets[i].rtl)) == STRICT_LOW_PART)
6989 /* REG_EQUAL in setting a STRICT_LOW_PART
6990 gives an equivalent for the entire destination register,
6991 not just for the subreg being stored in now.
6992 This is a more interesting equivalence, so we arrange later
6993 to treat the entire reg as the destination. */
6994 sets[i].src_elt = src_eqv_elt;
6995 sets[i].src_hash = src_eqv_hash;
6999 /* Insert source and constant equivalent into hash table, if not
7001 register struct table_elt *classp = src_eqv_elt;
7002 register rtx src = sets[i].src;
7003 register rtx dest = SET_DEST (sets[i].rtl);
7004 enum machine_mode mode
7005 = GET_MODE (src) == VOIDmode ? GET_MODE (dest) : GET_MODE (src);
7007 if (sets[i].src_elt == 0)
7009 register struct table_elt *elt;
7011 /* Note that these insert_regs calls cannot remove
7012 any of the src_elt's, because they would have failed to
7013 match if not still valid. */
7014 if (insert_regs (src, classp, 0))
7015 sets[i].src_hash = HASH (src, mode);
7016 elt = insert (src, classp, sets[i].src_hash, mode);
7017 elt->in_memory = sets[i].src_in_memory;
7018 elt->in_struct = sets[i].src_in_struct;
7019 sets[i].src_elt = classp = elt;
7022 if (sets[i].src_const && sets[i].src_const_elt == 0
7023 && src != sets[i].src_const
7024 && ! rtx_equal_p (sets[i].src_const, src))
7025 sets[i].src_elt = insert (sets[i].src_const, classp,
7026 sets[i].src_const_hash, mode);
7029 else if (sets[i].src_elt == 0)
7030 /* If we did not insert the source into the hash table (e.g., it was
7031 volatile), note the equivalence class for the REG_EQUAL value, if any,
7032 so that the destination goes into that class. */
7033 sets[i].src_elt = src_eqv_elt;
7035 invalidate_from_clobbers (&writes_memory, x);
7037 /* Some registers are invalidated by subroutine calls. Memory is
7038 invalidated by non-constant calls. */
7040 if (GET_CODE (insn) == CALL_INSN)
7042 static struct write_data everything = {0, 1, 1, 1};
7044 if (! CONST_CALL_P (insn))
7045 invalidate_memory (&everything);
7046 invalidate_for_call ();
7049 /* Now invalidate everything set by this instruction.
7050 If a SUBREG or other funny destination is being set,
7051 sets[i].rtl is still nonzero, so here we invalidate the reg
7052 a part of which is being set. */
7054 for (i = 0; i < n_sets; i++)
7057 register rtx dest = sets[i].inner_dest;
7059 /* Needed for registers to remove the register from its
7060 previous quantity's chain.
7061 Needed for memory if this is a nonvarying address, unless
7062 we have just done an invalidate_memory that covers even those. */
7063 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG
7064 || (! writes_memory.all && ! cse_rtx_addr_varies_p (dest)))
7066 else if (GET_CODE (dest) == STRICT_LOW_PART
7067 || GET_CODE (dest) == ZERO_EXTRACT)
7068 invalidate (XEXP (dest, 0));
7071 /* Make sure registers mentioned in destinations
7072 are safe for use in an expression to be inserted.
7073 This removes from the hash table
7074 any invalid entry that refers to one of these registers.
7076 We don't care about the return value from mention_regs because
7077 we are going to hash the SET_DEST values unconditionally. */
7079 for (i = 0; i < n_sets; i++)
7080 if (sets[i].rtl && GET_CODE (SET_DEST (sets[i].rtl)) != REG)
7081 mention_regs (SET_DEST (sets[i].rtl));
7083 /* We may have just removed some of the src_elt's from the hash table.
7084 So replace each one with the current head of the same class. */
7086 for (i = 0; i < n_sets; i++)
7089 if (sets[i].src_elt && sets[i].src_elt->first_same_value == 0)
7090 /* If elt was removed, find current head of same class,
7091 or 0 if nothing remains of that class. */
7093 register struct table_elt *elt = sets[i].src_elt;
7095 while (elt && elt->prev_same_value)
7096 elt = elt->prev_same_value;
7098 while (elt && elt->first_same_value == 0)
7099 elt = elt->next_same_value;
7100 sets[i].src_elt = elt ? elt->first_same_value : 0;
7104 /* Now insert the destinations into their equivalence classes. */
7106 for (i = 0; i < n_sets; i++)
7109 register rtx dest = SET_DEST (sets[i].rtl);
7110 register struct table_elt *elt;
7112 /* Don't record value if we are not supposed to risk allocating
7113 floating-point values in registers that might be wider than
7115 if ((flag_float_store
7116 && GET_CODE (dest) == MEM
7117 && FLOAT_MODE_P (GET_MODE (dest)))
7118 /* Don't record values of destinations set inside a libcall block
7119 since we might delete the libcall. Things should have been set
7120 up so we won't want to reuse such a value, but we play it safe
7123 /* If we didn't put a REG_EQUAL value or a source into the hash
7124 table, there is no point is recording DEST. */
7125 || sets[i].src_elt == 0)
7128 /* STRICT_LOW_PART isn't part of the value BEING set,
7129 and neither is the SUBREG inside it.
7130 Note that in this case SETS[I].SRC_ELT is really SRC_EQV_ELT. */
7131 if (GET_CODE (dest) == STRICT_LOW_PART)
7132 dest = SUBREG_REG (XEXP (dest, 0));
7134 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG)
7135 /* Registers must also be inserted into chains for quantities. */
7136 if (insert_regs (dest, sets[i].src_elt, 1))
7137 /* If `insert_regs' changes something, the hash code must be
7139 sets[i].dest_hash = HASH (dest, GET_MODE (dest));
7141 elt = insert (dest, sets[i].src_elt,
7142 sets[i].dest_hash, GET_MODE (dest));
7143 elt->in_memory = GET_CODE (sets[i].inner_dest) == MEM;
7146 /* This implicitly assumes a whole struct
7147 need not have MEM_IN_STRUCT_P.
7148 But a whole struct is *supposed* to have MEM_IN_STRUCT_P. */
7149 elt->in_struct = (MEM_IN_STRUCT_P (sets[i].inner_dest)
7150 || sets[i].inner_dest != SET_DEST (sets[i].rtl));
7153 /* If we have (set (subreg:m1 (reg:m2 foo) 0) (bar:m1)), M1 is no
7154 narrower than M2, and both M1 and M2 are the same number of words,
7155 we are also doing (set (reg:m2 foo) (subreg:m2 (bar:m1) 0)) so
7156 make that equivalence as well.
7158 However, BAR may have equivalences for which gen_lowpart_if_possible
7159 will produce a simpler value than gen_lowpart_if_possible applied to
7160 BAR (e.g., if BAR was ZERO_EXTENDed from M2), so we will scan all
7161 BAR's equivalences. If we don't get a simplified form, make
7162 the SUBREG. It will not be used in an equivalence, but will
7163 cause two similar assignments to be detected.
7165 Note the loop below will find SUBREG_REG (DEST) since we have
7166 already entered SRC and DEST of the SET in the table. */
7168 if (GET_CODE (dest) == SUBREG
7169 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))) - 1)
7171 == (GET_MODE_SIZE (GET_MODE (dest)) - 1)/ UNITS_PER_WORD)
7172 && (GET_MODE_SIZE (GET_MODE (dest))
7173 >= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))))
7174 && sets[i].src_elt != 0)
7176 enum machine_mode new_mode = GET_MODE (SUBREG_REG (dest));
7177 struct table_elt *elt, *classp = 0;
7179 for (elt = sets[i].src_elt->first_same_value; elt;
7180 elt = elt->next_same_value)
7184 struct table_elt *src_elt;
7186 /* Ignore invalid entries. */
7187 if (GET_CODE (elt->exp) != REG
7188 && ! exp_equiv_p (elt->exp, elt->exp, 1, 0))
7191 new_src = gen_lowpart_if_possible (new_mode, elt->exp);
7193 new_src = gen_rtx (SUBREG, new_mode, elt->exp, 0);
7195 src_hash = HASH (new_src, new_mode);
7196 src_elt = lookup (new_src, src_hash, new_mode);
7198 /* Put the new source in the hash table is if isn't
7202 if (insert_regs (new_src, classp, 0))
7203 src_hash = HASH (new_src, new_mode);
7204 src_elt = insert (new_src, classp, src_hash, new_mode);
7205 src_elt->in_memory = elt->in_memory;
7206 src_elt->in_struct = elt->in_struct;
7208 else if (classp && classp != src_elt->first_same_value)
7209 /* Show that two things that we've seen before are
7210 actually the same. */
7211 merge_equiv_classes (src_elt, classp);
7213 classp = src_elt->first_same_value;
7218 /* Special handling for (set REG0 REG1)
7219 where REG0 is the "cheapest", cheaper than REG1.
7220 After cse, REG1 will probably not be used in the sequel,
7221 so (if easily done) change this insn to (set REG1 REG0) and
7222 replace REG1 with REG0 in the previous insn that computed their value.
7223 Then REG1 will become a dead store and won't cloud the situation
7224 for later optimizations.
7226 Do not make this change if REG1 is a hard register, because it will
7227 then be used in the sequel and we may be changing a two-operand insn
7228 into a three-operand insn.
7230 Also do not do this if we are operating on a copy of INSN. */
7232 if (n_sets == 1 && sets[0].rtl && GET_CODE (SET_DEST (sets[0].rtl)) == REG
7233 && NEXT_INSN (PREV_INSN (insn)) == insn
7234 && GET_CODE (SET_SRC (sets[0].rtl)) == REG
7235 && REGNO (SET_SRC (sets[0].rtl)) >= FIRST_PSEUDO_REGISTER
7236 && REGNO_QTY_VALID_P (REGNO (SET_SRC (sets[0].rtl)))
7237 && (qty_first_reg[reg_qty[REGNO (SET_SRC (sets[0].rtl))]]
7238 == REGNO (SET_DEST (sets[0].rtl))))
7240 rtx prev = PREV_INSN (insn);
7241 while (prev && GET_CODE (prev) == NOTE)
7242 prev = PREV_INSN (prev);
7244 if (prev && GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SET
7245 && SET_DEST (PATTERN (prev)) == SET_SRC (sets[0].rtl))
7247 rtx dest = SET_DEST (sets[0].rtl);
7248 rtx note = find_reg_note (prev, REG_EQUIV, NULL_RTX);
7250 validate_change (prev, & SET_DEST (PATTERN (prev)), dest, 1);
7251 validate_change (insn, & SET_DEST (sets[0].rtl),
7252 SET_SRC (sets[0].rtl), 1);
7253 validate_change (insn, & SET_SRC (sets[0].rtl), dest, 1);
7254 apply_change_group ();
7256 /* If REG1 was equivalent to a constant, REG0 is not. */
7258 PUT_REG_NOTE_KIND (note, REG_EQUAL);
7260 /* If there was a REG_WAS_0 note on PREV, remove it. Move
7261 any REG_WAS_0 note on INSN to PREV. */
7262 note = find_reg_note (prev, REG_WAS_0, NULL_RTX);
7264 remove_note (prev, note);
7266 note = find_reg_note (insn, REG_WAS_0, NULL_RTX);
7269 remove_note (insn, note);
7270 XEXP (note, 1) = REG_NOTES (prev);
7271 REG_NOTES (prev) = note;
7276 /* If this is a conditional jump insn, record any known equivalences due to
7277 the condition being tested. */
7279 last_jump_equiv_class = 0;
7280 if (GET_CODE (insn) == JUMP_INSN
7281 && n_sets == 1 && GET_CODE (x) == SET
7282 && GET_CODE (SET_SRC (x)) == IF_THEN_ELSE)
7283 record_jump_equiv (insn, 0);
7286 /* If the previous insn set CC0 and this insn no longer references CC0,
7287 delete the previous insn. Here we use the fact that nothing expects CC0
7288 to be valid over an insn, which is true until the final pass. */
7289 if (prev_insn && GET_CODE (prev_insn) == INSN
7290 && (tem = single_set (prev_insn)) != 0
7291 && SET_DEST (tem) == cc0_rtx
7292 && ! reg_mentioned_p (cc0_rtx, x))
7294 PUT_CODE (prev_insn, NOTE);
7295 NOTE_LINE_NUMBER (prev_insn) = NOTE_INSN_DELETED;
7296 NOTE_SOURCE_FILE (prev_insn) = 0;
7299 prev_insn_cc0 = this_insn_cc0;
7300 prev_insn_cc0_mode = this_insn_cc0_mode;
7306 /* Store 1 in *WRITES_PTR for those categories of memory ref
7307 that must be invalidated when the expression WRITTEN is stored in.
7308 If WRITTEN is null, say everything must be invalidated. */
7311 note_mem_written (written, writes_ptr)
7313 struct write_data *writes_ptr;
7315 static struct write_data everything = {0, 1, 1, 1};
7318 *writes_ptr = everything;
7319 else if (GET_CODE (written) == MEM)
7321 /* Pushing or popping the stack invalidates just the stack pointer. */
7322 rtx addr = XEXP (written, 0);
7323 if ((GET_CODE (addr) == PRE_DEC || GET_CODE (addr) == PRE_INC
7324 || GET_CODE (addr) == POST_DEC || GET_CODE (addr) == POST_INC)
7325 && GET_CODE (XEXP (addr, 0)) == REG
7326 && REGNO (XEXP (addr, 0)) == STACK_POINTER_REGNUM)
7331 else if (GET_MODE (written) == BLKmode)
7332 *writes_ptr = everything;
7333 /* (mem (scratch)) means clobber everything. */
7334 else if (GET_CODE (addr) == SCRATCH)
7335 *writes_ptr = everything;
7336 else if (cse_rtx_addr_varies_p (written))
7338 /* A varying address that is a sum indicates an array element,
7339 and that's just as good as a structure element
7340 in implying that we need not invalidate scalar variables.
7341 However, we must allow QImode aliasing of scalars, because the
7342 ANSI C standard allows character pointers to alias anything. */
7343 if (! ((MEM_IN_STRUCT_P (written)
7344 || GET_CODE (XEXP (written, 0)) == PLUS)
7345 && GET_MODE (written) != QImode))
7346 writes_ptr->all = 1;
7347 writes_ptr->nonscalar = 1;
7349 writes_ptr->var = 1;
7353 /* Perform invalidation on the basis of everything about an insn
7354 except for invalidating the actual places that are SET in it.
7355 This includes the places CLOBBERed, and anything that might
7356 alias with something that is SET or CLOBBERed.
7358 W points to the writes_memory for this insn, a struct write_data
7359 saying which kinds of memory references must be invalidated.
7360 X is the pattern of the insn. */
7363 invalidate_from_clobbers (w, x)
7364 struct write_data *w;
7367 /* If W->var is not set, W specifies no action.
7368 If W->all is set, this step gets all memory refs
7369 so they can be ignored in the rest of this function. */
7371 invalidate_memory (w);
7375 if (reg_tick[STACK_POINTER_REGNUM] >= 0)
7376 reg_tick[STACK_POINTER_REGNUM]++;
7378 /* This should be *very* rare. */
7379 if (TEST_HARD_REG_BIT (hard_regs_in_table, STACK_POINTER_REGNUM))
7380 invalidate (stack_pointer_rtx);
7383 if (GET_CODE (x) == CLOBBER)
7385 rtx ref = XEXP (x, 0);
7388 if (GET_CODE (ref) == REG || GET_CODE (ref) == SUBREG
7389 || (GET_CODE (ref) == MEM && ! w->all))
7391 else if (GET_CODE (ref) == STRICT_LOW_PART
7392 || GET_CODE (ref) == ZERO_EXTRACT)
7393 invalidate (XEXP (ref, 0));
7396 else if (GET_CODE (x) == PARALLEL)
7399 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
7401 register rtx y = XVECEXP (x, 0, i);
7402 if (GET_CODE (y) == CLOBBER)
7404 rtx ref = XEXP (y, 0);
7407 if (GET_CODE (ref) == REG || GET_CODE (ref) == SUBREG
7408 || (GET_CODE (ref) == MEM && !w->all))
7410 else if (GET_CODE (ref) == STRICT_LOW_PART
7411 || GET_CODE (ref) == ZERO_EXTRACT)
7412 invalidate (XEXP (ref, 0));
7419 /* Process X, part of the REG_NOTES of an insn. Look at any REG_EQUAL notes
7420 and replace any registers in them with either an equivalent constant
7421 or the canonical form of the register. If we are inside an address,
7422 only do this if the address remains valid.
7424 OBJECT is 0 except when within a MEM in which case it is the MEM.
7426 Return the replacement for X. */
7429 cse_process_notes (x, object)
7433 enum rtx_code code = GET_CODE (x);
7434 char *fmt = GET_RTX_FORMAT (code);
7450 XEXP (x, 0) = cse_process_notes (XEXP (x, 0), x);
7455 if (REG_NOTE_KIND (x) == REG_EQUAL)
7456 XEXP (x, 0) = cse_process_notes (XEXP (x, 0), NULL_RTX);
7458 XEXP (x, 1) = cse_process_notes (XEXP (x, 1), NULL_RTX);
7464 rtx new = cse_process_notes (XEXP (x, 0), object);
7465 /* We don't substitute VOIDmode constants into these rtx,
7466 since they would impede folding. */
7467 if (GET_MODE (new) != VOIDmode)
7468 validate_change (object, &XEXP (x, 0), new, 0);
7473 i = reg_qty[REGNO (x)];
7475 /* Return a constant or a constant register. */
7476 if (REGNO_QTY_VALID_P (REGNO (x))
7477 && qty_const[i] != 0
7478 && (CONSTANT_P (qty_const[i])
7479 || GET_CODE (qty_const[i]) == REG))
7481 rtx new = gen_lowpart_if_possible (GET_MODE (x), qty_const[i]);
7486 /* Otherwise, canonicalize this register. */
7487 return canon_reg (x, NULL_RTX);
7490 for (i = 0; i < GET_RTX_LENGTH (code); i++)
7492 validate_change (object, &XEXP (x, i),
7493 cse_process_notes (XEXP (x, i), object), 0);
7498 /* Find common subexpressions between the end test of a loop and the beginning
7499 of the loop. LOOP_START is the CODE_LABEL at the start of a loop.
7501 Often we have a loop where an expression in the exit test is used
7502 in the body of the loop. For example "while (*p) *q++ = *p++;".
7503 Because of the way we duplicate the loop exit test in front of the loop,
7504 however, we don't detect that common subexpression. This will be caught
7505 when global cse is implemented, but this is a quite common case.
7507 This function handles the most common cases of these common expressions.
7508 It is called after we have processed the basic block ending with the
7509 NOTE_INSN_LOOP_END note that ends a loop and the previous JUMP_INSN
7510 jumps to a label used only once. */
7513 cse_around_loop (loop_start)
7518 struct table_elt *p;
7520 /* If the jump at the end of the loop doesn't go to the start, we don't
7522 for (insn = PREV_INSN (loop_start);
7523 insn && (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0);
7524 insn = PREV_INSN (insn))
7528 || GET_CODE (insn) != NOTE
7529 || NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG)
7532 /* If the last insn of the loop (the end test) was an NE comparison,
7533 we will interpret it as an EQ comparison, since we fell through
7534 the loop. Any equivalences resulting from that comparison are
7535 therefore not valid and must be invalidated. */
7536 if (last_jump_equiv_class)
7537 for (p = last_jump_equiv_class->first_same_value; p;
7538 p = p->next_same_value)
7539 if (GET_CODE (p->exp) == MEM || GET_CODE (p->exp) == REG
7540 || GET_CODE (p->exp) == SUBREG)
7541 invalidate (p->exp);
7542 else if (GET_CODE (p->exp) == STRICT_LOW_PART
7543 || GET_CODE (p->exp) == ZERO_EXTRACT)
7544 invalidate (XEXP (p->exp, 0));
7546 /* Process insns starting after LOOP_START until we hit a CALL_INSN or
7547 a CODE_LABEL (we could handle a CALL_INSN, but it isn't worth it).
7549 The only thing we do with SET_DEST is invalidate entries, so we
7550 can safely process each SET in order. It is slightly less efficient
7551 to do so, but we only want to handle the most common cases. */
7553 for (insn = NEXT_INSN (loop_start);
7554 GET_CODE (insn) != CALL_INSN && GET_CODE (insn) != CODE_LABEL
7555 && ! (GET_CODE (insn) == NOTE
7556 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
7557 insn = NEXT_INSN (insn))
7559 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
7560 && (GET_CODE (PATTERN (insn)) == SET
7561 || GET_CODE (PATTERN (insn)) == CLOBBER))
7562 cse_set_around_loop (PATTERN (insn), insn, loop_start);
7563 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
7564 && GET_CODE (PATTERN (insn)) == PARALLEL)
7565 for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
7566 if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == SET
7567 || GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == CLOBBER)
7568 cse_set_around_loop (XVECEXP (PATTERN (insn), 0, i), insn,
7573 /* Variable used for communications between the next two routines. */
7575 static struct write_data skipped_writes_memory;
7577 /* Process one SET of an insn that was skipped. We ignore CLOBBERs
7578 since they are done elsewhere. This function is called via note_stores. */
7581 invalidate_skipped_set (dest, set)
7585 if (GET_CODE (set) == CLOBBER
7592 if (GET_CODE (dest) == MEM)
7593 note_mem_written (dest, &skipped_writes_memory);
7595 /* There are times when an address can appear varying and be a PLUS
7596 during this scan when it would be a fixed address were we to know
7597 the proper equivalences. So promote "nonscalar" to be "all". */
7598 if (skipped_writes_memory.nonscalar)
7599 skipped_writes_memory.all = 1;
7601 if (GET_CODE (dest) == REG || GET_CODE (dest) == SUBREG
7602 || (! skipped_writes_memory.all && ! cse_rtx_addr_varies_p (dest)))
7604 else if (GET_CODE (dest) == STRICT_LOW_PART
7605 || GET_CODE (dest) == ZERO_EXTRACT)
7606 invalidate (XEXP (dest, 0));
7609 /* Invalidate all insns from START up to the end of the function or the
7610 next label. This called when we wish to CSE around a block that is
7611 conditionally executed. */
7614 invalidate_skipped_block (start)
7618 static struct write_data init = {0, 0, 0, 0};
7619 static struct write_data everything = {0, 1, 1, 1};
7621 for (insn = start; insn && GET_CODE (insn) != CODE_LABEL;
7622 insn = NEXT_INSN (insn))
7624 if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
7627 skipped_writes_memory = init;
7629 if (GET_CODE (insn) == CALL_INSN)
7631 invalidate_for_call ();
7632 skipped_writes_memory = everything;
7635 note_stores (PATTERN (insn), invalidate_skipped_set);
7636 invalidate_from_clobbers (&skipped_writes_memory, PATTERN (insn));
7640 /* Used for communication between the following two routines; contains a
7641 value to be checked for modification. */
7643 static rtx cse_check_loop_start_value;
7645 /* If modifying X will modify the value in CSE_CHECK_LOOP_START_VALUE,
7646 indicate that fact by setting CSE_CHECK_LOOP_START_VALUE to 0. */
7649 cse_check_loop_start (x, set)
7653 if (cse_check_loop_start_value == 0
7654 || GET_CODE (x) == CC0 || GET_CODE (x) == PC)
7657 if ((GET_CODE (x) == MEM && GET_CODE (cse_check_loop_start_value) == MEM)
7658 || reg_overlap_mentioned_p (x, cse_check_loop_start_value))
7659 cse_check_loop_start_value = 0;
7662 /* X is a SET or CLOBBER contained in INSN that was found near the start of
7663 a loop that starts with the label at LOOP_START.
7665 If X is a SET, we see if its SET_SRC is currently in our hash table.
7666 If so, we see if it has a value equal to some register used only in the
7667 loop exit code (as marked by jump.c).
7669 If those two conditions are true, we search backwards from the start of
7670 the loop to see if that same value was loaded into a register that still
7671 retains its value at the start of the loop.
7673 If so, we insert an insn after the load to copy the destination of that
7674 load into the equivalent register and (try to) replace our SET_SRC with that
7677 In any event, we invalidate whatever this SET or CLOBBER modifies. */
7680 cse_set_around_loop (x, insn, loop_start)
7685 struct table_elt *src_elt;
7686 static struct write_data init = {0, 0, 0, 0};
7687 struct write_data writes_memory;
7689 writes_memory = init;
7691 /* If this is a SET, see if we can replace SET_SRC, but ignore SETs that
7692 are setting PC or CC0 or whose SET_SRC is already a register. */
7693 if (GET_CODE (x) == SET
7694 && GET_CODE (SET_DEST (x)) != PC && GET_CODE (SET_DEST (x)) != CC0
7695 && GET_CODE (SET_SRC (x)) != REG)
7697 src_elt = lookup (SET_SRC (x),
7698 HASH (SET_SRC (x), GET_MODE (SET_DEST (x))),
7699 GET_MODE (SET_DEST (x)));
7702 for (src_elt = src_elt->first_same_value; src_elt;
7703 src_elt = src_elt->next_same_value)
7704 if (GET_CODE (src_elt->exp) == REG && REG_LOOP_TEST_P (src_elt->exp)
7705 && COST (src_elt->exp) < COST (SET_SRC (x)))
7709 /* Look for an insn in front of LOOP_START that sets
7710 something in the desired mode to SET_SRC (x) before we hit
7711 a label or CALL_INSN. */
7713 for (p = prev_nonnote_insn (loop_start);
7714 p && GET_CODE (p) != CALL_INSN
7715 && GET_CODE (p) != CODE_LABEL;
7716 p = prev_nonnote_insn (p))
7717 if ((set = single_set (p)) != 0
7718 && GET_CODE (SET_DEST (set)) == REG
7719 && GET_MODE (SET_DEST (set)) == src_elt->mode
7720 && rtx_equal_p (SET_SRC (set), SET_SRC (x)))
7722 /* We now have to ensure that nothing between P
7723 and LOOP_START modified anything referenced in
7724 SET_SRC (x). We know that nothing within the loop
7725 can modify it, or we would have invalidated it in
7729 cse_check_loop_start_value = SET_SRC (x);
7730 for (q = p; q != loop_start; q = NEXT_INSN (q))
7731 if (GET_RTX_CLASS (GET_CODE (q)) == 'i')
7732 note_stores (PATTERN (q), cse_check_loop_start);
7734 /* If nothing was changed and we can replace our
7735 SET_SRC, add an insn after P to copy its destination
7736 to what we will be replacing SET_SRC with. */
7737 if (cse_check_loop_start_value
7738 && validate_change (insn, &SET_SRC (x),
7740 emit_insn_after (gen_move_insn (src_elt->exp,
7748 /* Now invalidate anything modified by X. */
7749 note_mem_written (SET_DEST (x), &writes_memory);
7751 if (writes_memory.var)
7752 invalidate_memory (&writes_memory);
7754 /* See comment on similar code in cse_insn for explanation of these tests. */
7755 if (GET_CODE (SET_DEST (x)) == REG || GET_CODE (SET_DEST (x)) == SUBREG
7756 || (GET_CODE (SET_DEST (x)) == MEM && ! writes_memory.all
7757 && ! cse_rtx_addr_varies_p (SET_DEST (x))))
7758 invalidate (SET_DEST (x));
7759 else if (GET_CODE (SET_DEST (x)) == STRICT_LOW_PART
7760 || GET_CODE (SET_DEST (x)) == ZERO_EXTRACT)
7761 invalidate (XEXP (SET_DEST (x), 0));
7764 /* Find the end of INSN's basic block and return its range,
7765 the total number of SETs in all the insns of the block, the last insn of the
7766 block, and the branch path.
7768 The branch path indicates which branches should be followed. If a non-zero
7769 path size is specified, the block should be rescanned and a different set
7770 of branches will be taken. The branch path is only used if
7771 FLAG_CSE_FOLLOW_JUMPS or FLAG_CSE_SKIP_BLOCKS is non-zero.
7773 DATA is a pointer to a struct cse_basic_block_data, defined below, that is
7774 used to describe the block. It is filled in with the information about
7775 the current block. The incoming structure's branch path, if any, is used
7776 to construct the output branch path. */
7779 cse_end_of_basic_block (insn, data, follow_jumps, after_loop, skip_blocks)
7781 struct cse_basic_block_data *data;
7788 int low_cuid = INSN_CUID (insn), high_cuid = INSN_CUID (insn);
7789 rtx next = GET_RTX_CLASS (GET_CODE (insn)) == 'i' ? insn : next_real_insn (insn);
7790 int path_size = data->path_size;
7794 /* Update the previous branch path, if any. If the last branch was
7795 previously TAKEN, mark it NOT_TAKEN. If it was previously NOT_TAKEN,
7796 shorten the path by one and look at the previous branch. We know that
7797 at least one branch must have been taken if PATH_SIZE is non-zero. */
7798 while (path_size > 0)
7800 if (data->path[path_size - 1].status != NOT_TAKEN)
7802 data->path[path_size - 1].status = NOT_TAKEN;
7809 /* Scan to end of this basic block. */
7810 while (p && GET_CODE (p) != CODE_LABEL)
7812 /* Don't cse out the end of a loop. This makes a difference
7813 only for the unusual loops that always execute at least once;
7814 all other loops have labels there so we will stop in any case.
7815 Cse'ing out the end of the loop is dangerous because it
7816 might cause an invariant expression inside the loop
7817 to be reused after the end of the loop. This would make it
7818 hard to move the expression out of the loop in loop.c,
7819 especially if it is one of several equivalent expressions
7820 and loop.c would like to eliminate it.
7822 If we are running after loop.c has finished, we can ignore
7823 the NOTE_INSN_LOOP_END. */
7825 if (! after_loop && GET_CODE (p) == NOTE
7826 && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END)
7829 /* Don't cse over a call to setjmp; on some machines (eg vax)
7830 the regs restored by the longjmp come from
7831 a later time than the setjmp. */
7832 if (GET_CODE (p) == NOTE
7833 && NOTE_LINE_NUMBER (p) == NOTE_INSN_SETJMP)
7836 /* A PARALLEL can have lots of SETs in it,
7837 especially if it is really an ASM_OPERANDS. */
7838 if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
7839 && GET_CODE (PATTERN (p)) == PARALLEL)
7840 nsets += XVECLEN (PATTERN (p), 0);
7841 else if (GET_CODE (p) != NOTE)
7844 /* Ignore insns made by CSE; they cannot affect the boundaries of
7847 if (INSN_UID (p) <= max_uid && INSN_CUID (p) > high_cuid)
7848 high_cuid = INSN_CUID (p);
7849 if (INSN_UID (p) <= max_uid && INSN_CUID (p) < low_cuid)
7850 low_cuid = INSN_CUID (p);
7852 /* See if this insn is in our branch path. If it is and we are to
7854 if (path_entry < path_size && data->path[path_entry].branch == p)
7856 if (data->path[path_entry].status != NOT_TAKEN)
7859 /* Point to next entry in path, if any. */
7863 /* If this is a conditional jump, we can follow it if -fcse-follow-jumps
7864 was specified, we haven't reached our maximum path length, there are
7865 insns following the target of the jump, this is the only use of the
7866 jump label, and the target label is preceded by a BARRIER.
7868 Alternatively, we can follow the jump if it branches around a
7869 block of code and there are no other branches into the block.
7870 In this case invalidate_skipped_block will be called to invalidate any
7871 registers set in the block when following the jump. */
7873 else if ((follow_jumps || skip_blocks) && path_size < PATHLENGTH - 1
7874 && GET_CODE (p) == JUMP_INSN
7875 && GET_CODE (PATTERN (p)) == SET
7876 && GET_CODE (SET_SRC (PATTERN (p))) == IF_THEN_ELSE
7877 && LABEL_NUSES (JUMP_LABEL (p)) == 1
7878 && NEXT_INSN (JUMP_LABEL (p)) != 0)
7880 for (q = PREV_INSN (JUMP_LABEL (p)); q; q = PREV_INSN (q))
7881 if ((GET_CODE (q) != NOTE
7882 || NOTE_LINE_NUMBER (q) == NOTE_INSN_LOOP_END
7883 || NOTE_LINE_NUMBER (q) == NOTE_INSN_SETJMP)
7884 && (GET_CODE (q) != CODE_LABEL || LABEL_NUSES (q) != 0))
7887 /* If we ran into a BARRIER, this code is an extension of the
7888 basic block when the branch is taken. */
7889 if (follow_jumps && q != 0 && GET_CODE (q) == BARRIER)
7891 /* Don't allow ourself to keep walking around an
7892 always-executed loop. */
7893 if (next_real_insn (q) == next)
7899 /* Similarly, don't put a branch in our path more than once. */
7900 for (i = 0; i < path_entry; i++)
7901 if (data->path[i].branch == p)
7904 if (i != path_entry)
7907 data->path[path_entry].branch = p;
7908 data->path[path_entry++].status = TAKEN;
7910 /* This branch now ends our path. It was possible that we
7911 didn't see this branch the last time around (when the
7912 insn in front of the target was a JUMP_INSN that was
7913 turned into a no-op). */
7914 path_size = path_entry;
7917 /* Mark block so we won't scan it again later. */
7918 PUT_MODE (NEXT_INSN (p), QImode);
7920 /* Detect a branch around a block of code. */
7921 else if (skip_blocks && q != 0 && GET_CODE (q) != CODE_LABEL)
7925 if (next_real_insn (q) == next)
7931 for (i = 0; i < path_entry; i++)
7932 if (data->path[i].branch == p)
7935 if (i != path_entry)
7938 /* This is no_labels_between_p (p, q) with an added check for
7939 reaching the end of a function (in case Q precedes P). */
7940 for (tmp = NEXT_INSN (p); tmp && tmp != q; tmp = NEXT_INSN (tmp))
7941 if (GET_CODE (tmp) == CODE_LABEL)
7946 data->path[path_entry].branch = p;
7947 data->path[path_entry++].status = AROUND;
7949 path_size = path_entry;
7952 /* Mark block so we won't scan it again later. */
7953 PUT_MODE (NEXT_INSN (p), QImode);
7960 data->low_cuid = low_cuid;
7961 data->high_cuid = high_cuid;
7962 data->nsets = nsets;
7965 /* If all jumps in the path are not taken, set our path length to zero
7966 so a rescan won't be done. */
7967 for (i = path_size - 1; i >= 0; i--)
7968 if (data->path[i].status != NOT_TAKEN)
7972 data->path_size = 0;
7974 data->path_size = path_size;
7976 /* End the current branch path. */
7977 data->path[path_size].branch = 0;
7980 /* Perform cse on the instructions of a function.
7981 F is the first instruction.
7982 NREGS is one plus the highest pseudo-reg number used in the instruction.
7984 AFTER_LOOP is 1 if this is the cse call done after loop optimization
7985 (only if -frerun-cse-after-loop).
7987 Returns 1 if jump_optimize should be redone due to simplifications
7988 in conditional jump instructions. */
7991 cse_main (f, nregs, after_loop, file)
7997 struct cse_basic_block_data val;
7998 register rtx insn = f;
8001 cse_jumps_altered = 0;
8002 constant_pool_entries_cost = 0;
8009 all_minus_one = (int *) alloca (nregs * sizeof (int));
8010 consec_ints = (int *) alloca (nregs * sizeof (int));
8012 for (i = 0; i < nregs; i++)
8014 all_minus_one[i] = -1;
8018 reg_next_eqv = (int *) alloca (nregs * sizeof (int));
8019 reg_prev_eqv = (int *) alloca (nregs * sizeof (int));
8020 reg_qty = (int *) alloca (nregs * sizeof (int));
8021 reg_in_table = (int *) alloca (nregs * sizeof (int));
8022 reg_tick = (int *) alloca (nregs * sizeof (int));
8024 #ifdef LOAD_EXTEND_OP
8026 /* Allocate scratch rtl here. cse_insn will fill in the memory reference
8027 and change the code and mode as appropriate. */
8028 memory_extend_rtx = gen_rtx (ZERO_EXTEND, VOIDmode, 0);
8031 /* Discard all the free elements of the previous function
8032 since they are allocated in the temporarily obstack. */
8033 bzero ((char *) table, sizeof table);
8034 free_element_chain = 0;
8035 n_elements_made = 0;
8037 /* Find the largest uid. */
8039 max_uid = get_max_uid ();
8040 uid_cuid = (int *) alloca ((max_uid + 1) * sizeof (int));
8041 bzero ((char *) uid_cuid, (max_uid + 1) * sizeof (int));
8043 /* Compute the mapping from uids to cuids.
8044 CUIDs are numbers assigned to insns, like uids,
8045 except that cuids increase monotonically through the code.
8046 Don't assign cuids to line-number NOTEs, so that the distance in cuids
8047 between two insns is not affected by -g. */
8049 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
8051 if (GET_CODE (insn) != NOTE
8052 || NOTE_LINE_NUMBER (insn) < 0)
8053 INSN_CUID (insn) = ++i;
8055 /* Give a line number note the same cuid as preceding insn. */
8056 INSN_CUID (insn) = i;
8059 /* Initialize which registers are clobbered by calls. */
8061 CLEAR_HARD_REG_SET (regs_invalidated_by_call);
8063 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
8064 if ((call_used_regs[i]
8065 /* Used to check !fixed_regs[i] here, but that isn't safe;
8066 fixed regs are still call-clobbered, and sched can get
8067 confused if they can "live across calls".
8069 The frame pointer is always preserved across calls. The arg
8070 pointer is if it is fixed. The stack pointer usually is, unless
8071 RETURN_POPS_ARGS, in which case an explicit CLOBBER
8072 will be present. If we are generating PIC code, the PIC offset
8073 table register is preserved across calls. */
8075 && i != STACK_POINTER_REGNUM
8076 && i != FRAME_POINTER_REGNUM
8077 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
8078 && i != HARD_FRAME_POINTER_REGNUM
8080 #if ARG_POINTER_REGNUM != FRAME_POINTER_REGNUM
8081 && ! (i == ARG_POINTER_REGNUM && fixed_regs[i])
8083 #if defined (PIC_OFFSET_TABLE_REGNUM) && !defined (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED)
8084 && ! (i == PIC_OFFSET_TABLE_REGNUM && flag_pic)
8088 SET_HARD_REG_BIT (regs_invalidated_by_call, i);
8090 /* Loop over basic blocks.
8091 Compute the maximum number of qty's needed for each basic block
8092 (which is 2 for each SET). */
8096 cse_end_of_basic_block (insn, &val, flag_cse_follow_jumps, after_loop,
8097 flag_cse_skip_blocks);
8099 /* If this basic block was already processed or has no sets, skip it. */
8100 if (val.nsets == 0 || GET_MODE (insn) == QImode)
8102 PUT_MODE (insn, VOIDmode);
8103 insn = (val.last ? NEXT_INSN (val.last) : 0);
8108 cse_basic_block_start = val.low_cuid;
8109 cse_basic_block_end = val.high_cuid;
8110 max_qty = val.nsets * 2;
8113 fprintf (file, ";; Processing block from %d to %d, %d sets.\n",
8114 INSN_UID (insn), val.last ? INSN_UID (val.last) : 0,
8117 /* Make MAX_QTY bigger to give us room to optimize
8118 past the end of this basic block, if that should prove useful. */
8124 /* If this basic block is being extended by following certain jumps,
8125 (see `cse_end_of_basic_block'), we reprocess the code from the start.
8126 Otherwise, we start after this basic block. */
8127 if (val.path_size > 0)
8128 cse_basic_block (insn, val.last, val.path, 0);
8131 int old_cse_jumps_altered = cse_jumps_altered;
8134 /* When cse changes a conditional jump to an unconditional
8135 jump, we want to reprocess the block, since it will give
8136 us a new branch path to investigate. */
8137 cse_jumps_altered = 0;
8138 temp = cse_basic_block (insn, val.last, val.path, ! after_loop);
8139 if (cse_jumps_altered == 0
8140 || (flag_cse_follow_jumps == 0 && flag_cse_skip_blocks == 0))
8143 cse_jumps_altered |= old_cse_jumps_altered;
8151 /* Tell refers_to_mem_p that qty_const info is not available. */
8154 if (max_elements_made < n_elements_made)
8155 max_elements_made = n_elements_made;
8157 return cse_jumps_altered;
8160 /* Process a single basic block. FROM and TO and the limits of the basic
8161 block. NEXT_BRANCH points to the branch path when following jumps or
8162 a null path when not following jumps.
8164 AROUND_LOOP is non-zero if we are to try to cse around to the start of a
8165 loop. This is true when we are being called for the last time on a
8166 block and this CSE pass is before loop.c. */
8169 cse_basic_block (from, to, next_branch, around_loop)
8170 register rtx from, to;
8171 struct branch_path *next_branch;
8176 int in_libcall_block = 0;
8178 /* Each of these arrays is undefined before max_reg, so only allocate
8179 the space actually needed and adjust the start below. */
8181 qty_first_reg = (int *) alloca ((max_qty - max_reg) * sizeof (int));
8182 qty_last_reg = (int *) alloca ((max_qty - max_reg) * sizeof (int));
8183 qty_mode= (enum machine_mode *) alloca ((max_qty - max_reg) * sizeof (enum machine_mode));
8184 qty_const = (rtx *) alloca ((max_qty - max_reg) * sizeof (rtx));
8185 qty_const_insn = (rtx *) alloca ((max_qty - max_reg) * sizeof (rtx));
8187 = (enum rtx_code *) alloca ((max_qty - max_reg) * sizeof (enum rtx_code));
8188 qty_comparison_qty = (int *) alloca ((max_qty - max_reg) * sizeof (int));
8189 qty_comparison_const = (rtx *) alloca ((max_qty - max_reg) * sizeof (rtx));
8191 qty_first_reg -= max_reg;
8192 qty_last_reg -= max_reg;
8193 qty_mode -= max_reg;
8194 qty_const -= max_reg;
8195 qty_const_insn -= max_reg;
8196 qty_comparison_code -= max_reg;
8197 qty_comparison_qty -= max_reg;
8198 qty_comparison_const -= max_reg;
8202 /* TO might be a label. If so, protect it from being deleted. */
8203 if (to != 0 && GET_CODE (to) == CODE_LABEL)
8206 for (insn = from; insn != to; insn = NEXT_INSN (insn))
8208 register enum rtx_code code;
8210 /* See if this is a branch that is part of the path. If so, and it is
8211 to be taken, do so. */
8212 if (next_branch->branch == insn)
8214 enum taken status = next_branch++->status;
8215 if (status != NOT_TAKEN)
8217 if (status == TAKEN)
8218 record_jump_equiv (insn, 1);
8220 invalidate_skipped_block (NEXT_INSN (insn));
8222 /* Set the last insn as the jump insn; it doesn't affect cc0.
8223 Then follow this branch. */
8228 insn = JUMP_LABEL (insn);
8233 code = GET_CODE (insn);
8234 if (GET_MODE (insn) == QImode)
8235 PUT_MODE (insn, VOIDmode);
8237 if (GET_RTX_CLASS (code) == 'i')
8239 /* Process notes first so we have all notes in canonical forms when
8240 looking for duplicate operations. */
8242 if (REG_NOTES (insn))
8243 REG_NOTES (insn) = cse_process_notes (REG_NOTES (insn), NULL_RTX);
8245 /* Track when we are inside in LIBCALL block. Inside such a block,
8246 we do not want to record destinations. The last insn of a
8247 LIBCALL block is not considered to be part of the block, since
8248 its destination is the result of the block and hence should be
8251 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
8252 in_libcall_block = 1;
8253 else if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
8254 in_libcall_block = 0;
8256 cse_insn (insn, in_libcall_block);
8259 /* If INSN is now an unconditional jump, skip to the end of our
8260 basic block by pretending that we just did the last insn in the
8261 basic block. If we are jumping to the end of our block, show
8262 that we can have one usage of TO. */
8264 if (simplejump_p (insn))
8269 if (JUMP_LABEL (insn) == to)
8272 /* Maybe TO was deleted because the jump is unconditional.
8273 If so, there is nothing left in this basic block. */
8274 /* ??? Perhaps it would be smarter to set TO
8275 to whatever follows this insn,
8276 and pretend the basic block had always ended here. */
8277 if (INSN_DELETED_P (to))
8280 insn = PREV_INSN (to);
8283 /* See if it is ok to keep on going past the label
8284 which used to end our basic block. Remember that we incremented
8285 the count of that label, so we decrement it here. If we made
8286 a jump unconditional, TO_USAGE will be one; in that case, we don't
8287 want to count the use in that jump. */
8289 if (to != 0 && NEXT_INSN (insn) == to
8290 && GET_CODE (to) == CODE_LABEL && --LABEL_NUSES (to) == to_usage)
8292 struct cse_basic_block_data val;
8294 insn = NEXT_INSN (to);
8296 if (LABEL_NUSES (to) == 0)
8299 /* Find the end of the following block. Note that we won't be
8300 following branches in this case. If TO was the last insn
8301 in the function, we are done. Similarly, if we deleted the
8302 insn after TO, it must have been because it was preceded by
8303 a BARRIER. In that case, we are done with this block because it
8304 has no continuation. */
8306 if (insn == 0 || INSN_DELETED_P (insn))
8311 cse_end_of_basic_block (insn, &val, 0, 0, 0);
8313 /* If the tables we allocated have enough space left
8314 to handle all the SETs in the next basic block,
8315 continue through it. Otherwise, return,
8316 and that block will be scanned individually. */
8317 if (val.nsets * 2 + next_qty > max_qty)
8320 cse_basic_block_start = val.low_cuid;
8321 cse_basic_block_end = val.high_cuid;
8324 /* Prevent TO from being deleted if it is a label. */
8325 if (to != 0 && GET_CODE (to) == CODE_LABEL)
8328 /* Back up so we process the first insn in the extension. */
8329 insn = PREV_INSN (insn);
8333 if (next_qty > max_qty)
8336 /* If we are running before loop.c, we stopped on a NOTE_INSN_LOOP_END, and
8337 the previous insn is the only insn that branches to the head of a loop,
8338 we can cse into the loop. Don't do this if we changed the jump
8339 structure of a loop unless we aren't going to be following jumps. */
8341 if ((cse_jumps_altered == 0
8342 || (flag_cse_follow_jumps == 0 && flag_cse_skip_blocks == 0))
8343 && around_loop && to != 0
8344 && GET_CODE (to) == NOTE && NOTE_LINE_NUMBER (to) == NOTE_INSN_LOOP_END
8345 && GET_CODE (PREV_INSN (to)) == JUMP_INSN
8346 && JUMP_LABEL (PREV_INSN (to)) != 0
8347 && LABEL_NUSES (JUMP_LABEL (PREV_INSN (to))) == 1)
8348 cse_around_loop (JUMP_LABEL (PREV_INSN (to)));
8350 return to ? NEXT_INSN (to) : 0;
8353 /* Count the number of times registers are used (not set) in X.
8354 COUNTS is an array in which we accumulate the count, INCR is how much
8355 we count each register usage.
8357 Don't count a usage of DEST, which is the SET_DEST of a SET which
8358 contains X in its SET_SRC. This is because such a SET does not
8359 modify the liveness of DEST. */
8362 count_reg_usage (x, counts, dest, incr)
8375 switch (code = GET_CODE (x))
8379 counts[REGNO (x)] += incr;
8393 /* Unless we are setting a REG, count everything in SET_DEST. */
8394 if (GET_CODE (SET_DEST (x)) != REG)
8395 count_reg_usage (SET_DEST (x), counts, NULL_RTX, incr);
8397 /* If SRC has side-effects, then we can't delete this insn, so the
8398 usage of SET_DEST inside SRC counts.
8400 ??? Strictly-speaking, we might be preserving this insn
8401 because some other SET has side-effects, but that's hard
8402 to do and can't happen now. */
8403 count_reg_usage (SET_SRC (x), counts,
8404 side_effects_p (SET_SRC (x)) ? NULL_RTX : SET_DEST (x),
8409 count_reg_usage (CALL_INSN_FUNCTION_USAGE (x), counts, NULL_RTX, incr);
8411 /* ... falls through ... */
8414 count_reg_usage (PATTERN (x), counts, NULL_RTX, incr);
8416 /* Things used in a REG_EQUAL note aren't dead since loop may try to
8419 count_reg_usage (REG_NOTES (x), counts, NULL_RTX, incr);
8424 if (REG_NOTE_KIND (x) == REG_EQUAL
8425 || GET_CODE (XEXP (x,0)) == USE)
8426 count_reg_usage (XEXP (x, 0), counts, NULL_RTX, incr);
8427 count_reg_usage (XEXP (x, 1), counts, NULL_RTX, incr);
8431 fmt = GET_RTX_FORMAT (code);
8432 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
8435 count_reg_usage (XEXP (x, i), counts, dest, incr);
8436 else if (fmt[i] == 'E')
8437 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
8438 count_reg_usage (XVECEXP (x, i, j), counts, dest, incr);
8442 /* Scan all the insns and delete any that are dead; i.e., they store a register
8443 that is never used or they copy a register to itself.
8445 This is used to remove insns made obviously dead by cse. It improves the
8446 heuristics in loop since it won't try to move dead invariants out of loops
8447 or make givs for dead quantities. The remaining passes of the compilation
8448 are also sped up. */
8451 delete_dead_from_cse (insns, nreg)
8455 int *counts = (int *) alloca (nreg * sizeof (int));
8461 /* First count the number of times each register is used. */
8462 bzero ((char *) counts, sizeof (int) * nreg);
8463 for (insn = next_real_insn (insns); insn; insn = next_real_insn (insn))
8464 count_reg_usage (insn, counts, NULL_RTX, 1);
8466 /* Go from the last insn to the first and delete insns that only set unused
8467 registers or copy a register to itself. As we delete an insn, remove
8468 usage counts for registers it uses. */
8469 for (insn = prev_real_insn (get_last_insn ()); insn; insn = prev)
8473 prev = prev_real_insn (insn);
8475 /* Don't delete any insns that are part of a libcall block.
8476 Flow or loop might get confused if we did that. Remember
8477 that we are scanning backwards. */
8478 if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
8483 else if (GET_CODE (PATTERN (insn)) == SET)
8485 if (GET_CODE (SET_DEST (PATTERN (insn))) == REG
8486 && SET_DEST (PATTERN (insn)) == SET_SRC (PATTERN (insn)))
8490 else if (GET_CODE (SET_DEST (PATTERN (insn))) == CC0
8491 && ! side_effects_p (SET_SRC (PATTERN (insn)))
8492 && ((tem = next_nonnote_insn (insn)) == 0
8493 || GET_RTX_CLASS (GET_CODE (tem)) != 'i'
8494 || ! reg_referenced_p (cc0_rtx, PATTERN (tem))))
8497 else if (GET_CODE (SET_DEST (PATTERN (insn))) != REG
8498 || REGNO (SET_DEST (PATTERN (insn))) < FIRST_PSEUDO_REGISTER
8499 || counts[REGNO (SET_DEST (PATTERN (insn)))] != 0
8500 || side_effects_p (SET_SRC (PATTERN (insn))))
8503 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
8504 for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
8506 rtx elt = XVECEXP (PATTERN (insn), 0, i);
8508 if (GET_CODE (elt) == SET)
8510 if (GET_CODE (SET_DEST (elt)) == REG
8511 && SET_DEST (elt) == SET_SRC (elt))
8515 else if (GET_CODE (SET_DEST (elt)) == CC0
8516 && ! side_effects_p (SET_SRC (elt))
8517 && ((tem = next_nonnote_insn (insn)) == 0
8518 || GET_RTX_CLASS (GET_CODE (tem)) != 'i'
8519 || ! reg_referenced_p (cc0_rtx, PATTERN (tem))))
8522 else if (GET_CODE (SET_DEST (elt)) != REG
8523 || REGNO (SET_DEST (elt)) < FIRST_PSEUDO_REGISTER
8524 || counts[REGNO (SET_DEST (elt))] != 0
8525 || side_effects_p (SET_SRC (elt)))
8528 else if (GET_CODE (elt) != CLOBBER && GET_CODE (elt) != USE)
8534 /* If this is a dead insn, delete it and show registers in it aren't
8539 count_reg_usage (insn, counts, NULL_RTX, -1);
8543 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))