1 /* Register to Stack convert for GNU compiler.
2 Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This pass converts stack-like registers from the "flat register
23 file" model that gcc uses, to a stack convention that the 387 uses.
25 * The form of the input:
27 On input, the function consists of insn that have had their
28 registers fully allocated to a set of "virtual" registers. Note that
29 the word "virtual" is used differently here than elsewhere in gcc: for
30 each virtual stack reg, there is a hard reg, but the mapping between
31 them is not known until this pass is run. On output, hard register
32 numbers have been substituted, and various pop and exchange insns have
33 been emitted. The hard register numbers and the virtual register
34 numbers completely overlap - before this pass, all stack register
35 numbers are virtual, and afterward they are all hard.
37 The virtual registers can be manipulated normally by gcc, and their
38 semantics are the same as for normal registers. After the hard
39 register numbers are substituted, the semantics of an insn containing
40 stack-like regs are not the same as for an insn with normal regs: for
41 instance, it is not safe to delete an insn that appears to be a no-op
42 move. In general, no insn containing hard regs should be changed
43 after this pass is done.
45 * The form of the output:
47 After this pass, hard register numbers represent the distance from
48 the current top of stack to the desired register. A reference to
49 FIRST_STACK_REG references the top of stack, FIRST_STACK_REG + 1,
50 represents the register just below that, and so forth. Also, REG_DEAD
51 notes indicate whether or not a stack register should be popped.
53 A "swap" insn looks like a parallel of two patterns, where each
54 pattern is a SET: one sets A to B, the other B to A.
56 A "push" or "load" insn is a SET whose SET_DEST is FIRST_STACK_REG
57 and whose SET_DEST is REG or MEM. Any other SET_DEST, such as PLUS,
58 will replace the existing stack top, not push a new value.
60 A store insn is a SET whose SET_DEST is FIRST_STACK_REG, and whose
61 SET_SRC is REG or MEM.
63 The case where the SET_SRC and SET_DEST are both FIRST_STACK_REG
64 appears ambiguous. As a special case, the presence of a REG_DEAD note
65 for FIRST_STACK_REG differentiates between a load insn and a pop.
67 If a REG_DEAD is present, the insn represents a "pop" that discards
68 the top of the register stack. If there is no REG_DEAD note, then the
69 insn represents a "dup" or a push of the current top of stack onto the
74 Existing REG_DEAD and REG_UNUSED notes for stack registers are
75 deleted and recreated from scratch. REG_DEAD is never created for a
76 SET_DEST, only REG_UNUSED.
80 There are several rules on the usage of stack-like regs in
81 asm_operands insns. These rules apply only to the operands that are
84 1. Given a set of input regs that die in an asm_operands, it is
85 necessary to know which are implicitly popped by the asm, and
86 which must be explicitly popped by gcc.
88 An input reg that is implicitly popped by the asm must be
89 explicitly clobbered, unless it is constrained to match an
92 2. For any input reg that is implicitly popped by an asm, it is
93 necessary to know how to adjust the stack to compensate for the pop.
94 If any non-popped input is closer to the top of the reg-stack than
95 the implicitly popped reg, it would not be possible to know what the
96 stack looked like - it's not clear how the rest of the stack "slides
99 All implicitly popped input regs must be closer to the top of
100 the reg-stack than any input that is not implicitly popped.
102 3. It is possible that if an input dies in an insn, reload might
103 use the input reg for an output reload. Consider this example:
105 asm ("foo" : "=t" (a) : "f" (b));
107 This asm says that input B is not popped by the asm, and that
108 the asm pushes a result onto the reg-stack, i.e., the stack is one
109 deeper after the asm than it was before. But, it is possible that
110 reload will think that it can use the same reg for both the input and
111 the output, if input B dies in this insn.
113 If any input operand uses the "f" constraint, all output reg
114 constraints must use the "&" earlyclobber.
116 The asm above would be written as
118 asm ("foo" : "=&t" (a) : "f" (b));
120 4. Some operands need to be in particular places on the stack. All
121 output operands fall in this category - there is no other way to
122 know which regs the outputs appear in unless the user indicates
123 this in the constraints.
125 Output operands must specifically indicate which reg an output
126 appears in after an asm. "=f" is not allowed: the operand
127 constraints must select a class with a single reg.
129 5. Output operands may not be "inserted" between existing stack regs.
130 Since no 387 opcode uses a read/write operand, all output operands
131 are dead before the asm_operands, and are pushed by the asm_operands.
132 It makes no sense to push anywhere but the top of the reg-stack.
134 Output operands must start at the top of the reg-stack: output
135 operands may not "skip" a reg.
137 6. Some asm statements may need extra stack space for internal
138 calculations. This can be guaranteed by clobbering stack registers
139 unrelated to the inputs and outputs.
141 Here are a couple of reasonable asms to want to write. This asm
142 takes one input, which is internally popped, and produces two outputs.
144 asm ("fsincos" : "=t" (cos), "=u" (sin) : "0" (inp));
146 This asm takes two inputs, which are popped by the fyl2xp1 opcode,
147 and replaces them with one output. The user must code the "st(1)"
148 clobber for reg-stack.c to know that fyl2xp1 pops both inputs.
150 asm ("fyl2xp1" : "=t" (result) : "0" (x), "u" (y) : "st(1)");
156 #include "coretypes.h"
161 #include "function.h"
162 #include "insn-config.h"
164 #include "hard-reg-set.h"
169 #include "basic-block.h"
174 /* We use this array to cache info about insns, because otherwise we
175 spend too much time in stack_regs_mentioned_p.
177 Indexed by insn UIDs. A value of zero is uninitialized, one indicates
178 the insn uses stack registers, two indicates the insn does not use
180 static GTY(()) varray_type stack_regs_mentioned_data;
184 #define REG_STACK_SIZE (LAST_STACK_REG - FIRST_STACK_REG + 1)
186 /* This is the basic stack record. TOP is an index into REG[] such
187 that REG[TOP] is the top of stack. If TOP is -1 the stack is empty.
189 If TOP is -2, REG[] is not yet initialized. Stack initialization
190 consists of placing each live reg in array `reg' and setting `top'
193 REG_SET indicates which registers are live. */
195 typedef struct stack_def
197 int top; /* index to top stack element */
198 HARD_REG_SET reg_set; /* set of live registers */
199 unsigned char reg[REG_STACK_SIZE];/* register - stack mapping */
202 /* This is used to carry information about basic blocks. It is
203 attached to the AUX field of the standard CFG block. */
205 typedef struct block_info_def
207 struct stack_def stack_in; /* Input stack configuration. */
208 struct stack_def stack_out; /* Output stack configuration. */
209 HARD_REG_SET out_reg_set; /* Stack regs live on output. */
210 int done; /* True if block already converted. */
211 int predecessors; /* Number of predecessors that needs
215 #define BLOCK_INFO(B) ((block_info) (B)->aux)
217 /* Passed to change_stack to indicate where to emit insns. */
224 /* The block we're currently working on. */
225 static basic_block current_block;
227 /* This is the register file for all register after conversion. */
229 FP_mode_reg[LAST_STACK_REG+1-FIRST_STACK_REG][(int) MAX_MACHINE_MODE];
231 #define FP_MODE_REG(regno,mode) \
232 (FP_mode_reg[(regno)-FIRST_STACK_REG][(int) (mode)])
234 /* Used to initialize uninitialized registers. */
235 static rtx not_a_num;
237 /* Forward declarations */
239 static int stack_regs_mentioned_p (rtx pat);
240 static void straighten_stack (rtx, stack);
241 static void pop_stack (stack, int);
242 static rtx *get_true_reg (rtx *);
244 static int check_asm_stack_operands (rtx);
245 static int get_asm_operand_n_inputs (rtx);
246 static rtx stack_result (tree);
247 static void replace_reg (rtx *, int);
248 static void remove_regno_note (rtx, enum reg_note, unsigned int);
249 static int get_hard_regnum (stack, rtx);
250 static rtx emit_pop_insn (rtx, stack, rtx, enum emit_where);
251 static void emit_swap_insn (rtx, stack, rtx);
252 static void swap_to_top(rtx, stack, rtx, rtx);
253 static bool move_for_stack_reg (rtx, stack, rtx);
254 static bool move_nan_for_stack_reg (rtx, stack, rtx);
255 static int swap_rtx_condition_1 (rtx);
256 static int swap_rtx_condition (rtx);
257 static void compare_for_stack_reg (rtx, stack, rtx);
258 static bool subst_stack_regs_pat (rtx, stack, rtx);
259 static void subst_asm_stack_regs (rtx, stack);
260 static bool subst_stack_regs (rtx, stack);
261 static void change_stack (rtx, stack, stack, enum emit_where);
262 static int convert_regs_entry (void);
263 static void convert_regs_exit (void);
264 static int convert_regs_1 (FILE *, basic_block);
265 static int convert_regs_2 (FILE *, basic_block);
266 static int convert_regs (FILE *);
267 static void print_stack (FILE *, stack);
268 static rtx next_flags_user (rtx);
269 static bool compensate_edge (edge, FILE *);
271 /* Return nonzero if any stack register is mentioned somewhere within PAT. */
274 stack_regs_mentioned_p (rtx pat)
279 if (STACK_REG_P (pat))
282 fmt = GET_RTX_FORMAT (GET_CODE (pat));
283 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
289 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
290 if (stack_regs_mentioned_p (XVECEXP (pat, i, j)))
293 else if (fmt[i] == 'e' && stack_regs_mentioned_p (XEXP (pat, i)))
300 /* Return nonzero if INSN mentions stacked registers, else return zero. */
303 stack_regs_mentioned (rtx insn)
305 unsigned int uid, max;
308 if (! INSN_P (insn) || !stack_regs_mentioned_data)
311 uid = INSN_UID (insn);
312 max = VARRAY_SIZE (stack_regs_mentioned_data);
315 /* Allocate some extra size to avoid too many reallocs, but
316 do not grow too quickly. */
317 max = uid + uid / 20;
318 VARRAY_GROW (stack_regs_mentioned_data, max);
321 test = VARRAY_CHAR (stack_regs_mentioned_data, uid);
324 /* This insn has yet to be examined. Do so now. */
325 test = stack_regs_mentioned_p (PATTERN (insn)) ? 1 : 2;
326 VARRAY_CHAR (stack_regs_mentioned_data, uid) = test;
332 static rtx ix86_flags_rtx;
335 next_flags_user (rtx insn)
337 /* Search forward looking for the first use of this value.
338 Stop at block boundaries. */
340 while (insn != BB_END (current_block))
342 insn = NEXT_INSN (insn);
344 if (INSN_P (insn) && reg_mentioned_p (ix86_flags_rtx, PATTERN (insn)))
353 /* Reorganize the stack into ascending numbers,
357 straighten_stack (rtx insn, stack regstack)
359 struct stack_def temp_stack;
362 /* If there is only a single register on the stack, then the stack is
363 already in increasing order and no reorganization is needed.
365 Similarly if the stack is empty. */
366 if (regstack->top <= 0)
369 COPY_HARD_REG_SET (temp_stack.reg_set, regstack->reg_set);
371 for (top = temp_stack.top = regstack->top; top >= 0; top--)
372 temp_stack.reg[top] = FIRST_STACK_REG + temp_stack.top - top;
374 change_stack (insn, regstack, &temp_stack, EMIT_AFTER);
377 /* Pop a register from the stack. */
380 pop_stack (stack regstack, int regno)
382 int top = regstack->top;
384 CLEAR_HARD_REG_BIT (regstack->reg_set, regno);
386 /* If regno was not at the top of stack then adjust stack. */
387 if (regstack->reg [top] != regno)
390 for (i = regstack->top; i >= 0; i--)
391 if (regstack->reg [i] == regno)
394 for (j = i; j < top; j++)
395 regstack->reg [j] = regstack->reg [j + 1];
401 /* Convert register usage from "flat" register file usage to a "stack
402 register file. FILE is the dump file, if used.
404 Construct a CFG and run life analysis. Then convert each insn one
405 by one. Run a last cleanup_cfg pass, if optimizing, to eliminate
406 code duplication created when the converter inserts pop insns on
410 reg_to_stack (FILE *file)
416 /* Clean up previous run. */
417 stack_regs_mentioned_data = 0;
419 /* See if there is something to do. Flow analysis is quite
420 expensive so we might save some compilation time. */
421 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
422 if (regs_ever_live[i])
424 if (i > LAST_STACK_REG)
427 /* Ok, floating point instructions exist. If not optimizing,
428 build the CFG and run life analysis.
429 Also need to rebuild life when superblock scheduling is done
430 as it don't update liveness yet. */
432 || (flag_sched2_use_superblocks
433 && flag_schedule_insns_after_reload))
435 count_or_remove_death_notes (NULL, 1);
436 life_analysis (file, PROP_DEATH_NOTES);
438 mark_dfs_back_edges ();
440 /* Set up block info for each basic block. */
441 alloc_aux_for_blocks (sizeof (struct block_info_def));
442 FOR_EACH_BB_REVERSE (bb)
447 FOR_EACH_EDGE (e, ei, bb->preds)
448 if (!(e->flags & EDGE_DFS_BACK)
449 && e->src != ENTRY_BLOCK_PTR)
450 BLOCK_INFO (bb)->predecessors++;
453 /* Create the replacement registers up front. */
454 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
456 enum machine_mode mode;
457 for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT);
459 mode = GET_MODE_WIDER_MODE (mode))
460 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
461 for (mode = GET_CLASS_NARROWEST_MODE (MODE_COMPLEX_FLOAT);
463 mode = GET_MODE_WIDER_MODE (mode))
464 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
467 ix86_flags_rtx = gen_rtx_REG (CCmode, FLAGS_REG);
469 /* A QNaN for initializing uninitialized variables.
471 ??? We can't load from constant memory in PIC mode, because
472 we're inserting these instructions before the prologue and
473 the PIC register hasn't been set up. In that case, fall back
474 on zero, which we can get from `ldz'. */
477 not_a_num = CONST0_RTX (SFmode);
480 not_a_num = gen_lowpart (SFmode, GEN_INT (0x7fc00000));
481 not_a_num = force_const_mem (SFmode, not_a_num);
484 /* Allocate a cache for stack_regs_mentioned. */
485 max_uid = get_max_uid ();
486 VARRAY_CHAR_INIT (stack_regs_mentioned_data, max_uid + 1,
487 "stack_regs_mentioned cache");
491 free_aux_for_blocks ();
496 /* Return a pointer to the REG expression within PAT. If PAT is not a
497 REG, possible enclosed by a conversion rtx, return the inner part of
498 PAT that stopped the search. */
501 get_true_reg (rtx *pat)
504 switch (GET_CODE (*pat))
507 /* Eliminate FP subregister accesses in favor of the
508 actual FP register in use. */
511 if (FP_REG_P (subreg = SUBREG_REG (*pat)))
513 int regno_off = subreg_regno_offset (REGNO (subreg),
517 *pat = FP_MODE_REG (REGNO (subreg) + regno_off,
526 pat = & XEXP (*pat, 0);
530 if (!flag_unsafe_math_optimizations)
532 pat = & XEXP (*pat, 0);
537 /* Set if we find any malformed asms in a block. */
538 static bool any_malformed_asm;
540 /* There are many rules that an asm statement for stack-like regs must
541 follow. Those rules are explained at the top of this file: the rule
542 numbers below refer to that explanation. */
545 check_asm_stack_operands (rtx insn)
549 int malformed_asm = 0;
550 rtx body = PATTERN (insn);
552 char reg_used_as_output[FIRST_PSEUDO_REGISTER];
553 char implicitly_dies[FIRST_PSEUDO_REGISTER];
556 rtx *clobber_reg = 0;
557 int n_inputs, n_outputs;
559 /* Find out what the constraints require. If no constraint
560 alternative matches, this asm is malformed. */
562 constrain_operands (1);
563 alt = which_alternative;
565 preprocess_constraints ();
567 n_inputs = get_asm_operand_n_inputs (body);
568 n_outputs = recog_data.n_operands - n_inputs;
573 /* Avoid further trouble with this insn. */
574 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
578 /* Strip SUBREGs here to make the following code simpler. */
579 for (i = 0; i < recog_data.n_operands; i++)
580 if (GET_CODE (recog_data.operand[i]) == SUBREG
581 && REG_P (SUBREG_REG (recog_data.operand[i])))
582 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
584 /* Set up CLOBBER_REG. */
588 if (GET_CODE (body) == PARALLEL)
590 clobber_reg = alloca (XVECLEN (body, 0) * sizeof (rtx));
592 for (i = 0; i < XVECLEN (body, 0); i++)
593 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
595 rtx clobber = XVECEXP (body, 0, i);
596 rtx reg = XEXP (clobber, 0);
598 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
599 reg = SUBREG_REG (reg);
601 if (STACK_REG_P (reg))
603 clobber_reg[n_clobbers] = reg;
609 /* Enforce rule #4: Output operands must specifically indicate which
610 reg an output appears in after an asm. "=f" is not allowed: the
611 operand constraints must select a class with a single reg.
613 Also enforce rule #5: Output operands must start at the top of
614 the reg-stack: output operands may not "skip" a reg. */
616 memset (reg_used_as_output, 0, sizeof (reg_used_as_output));
617 for (i = 0; i < n_outputs; i++)
618 if (STACK_REG_P (recog_data.operand[i]))
620 if (reg_class_size[(int) recog_op_alt[i][alt].cl] != 1)
622 error_for_asm (insn, "output constraint %d must specify a single register", i);
629 for (j = 0; j < n_clobbers; j++)
630 if (REGNO (recog_data.operand[i]) == REGNO (clobber_reg[j]))
632 error_for_asm (insn, "output constraint %d cannot be specified together with \"%s\" clobber",
633 i, reg_names [REGNO (clobber_reg[j])]);
638 reg_used_as_output[REGNO (recog_data.operand[i])] = 1;
643 /* Search for first non-popped reg. */
644 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
645 if (! reg_used_as_output[i])
648 /* If there are any other popped regs, that's an error. */
649 for (; i < LAST_STACK_REG + 1; i++)
650 if (reg_used_as_output[i])
653 if (i != LAST_STACK_REG + 1)
655 error_for_asm (insn, "output regs must be grouped at top of stack");
659 /* Enforce rule #2: All implicitly popped input regs must be closer
660 to the top of the reg-stack than any input that is not implicitly
663 memset (implicitly_dies, 0, sizeof (implicitly_dies));
664 for (i = n_outputs; i < n_outputs + n_inputs; i++)
665 if (STACK_REG_P (recog_data.operand[i]))
667 /* An input reg is implicitly popped if it is tied to an
668 output, or if there is a CLOBBER for it. */
671 for (j = 0; j < n_clobbers; j++)
672 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
675 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
676 implicitly_dies[REGNO (recog_data.operand[i])] = 1;
679 /* Search for first non-popped reg. */
680 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
681 if (! implicitly_dies[i])
684 /* If there are any other popped regs, that's an error. */
685 for (; i < LAST_STACK_REG + 1; i++)
686 if (implicitly_dies[i])
689 if (i != LAST_STACK_REG + 1)
692 "implicitly popped regs must be grouped at top of stack");
696 /* Enforce rule #3: If any input operand uses the "f" constraint, all
697 output constraints must use the "&" earlyclobber.
699 ??? Detect this more deterministically by having constrain_asm_operands
700 record any earlyclobber. */
702 for (i = n_outputs; i < n_outputs + n_inputs; i++)
703 if (recog_op_alt[i][alt].matches == -1)
707 for (j = 0; j < n_outputs; j++)
708 if (operands_match_p (recog_data.operand[j], recog_data.operand[i]))
711 "output operand %d must use %<&%> constraint", j);
718 /* Avoid further trouble with this insn. */
719 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
720 any_malformed_asm = true;
727 /* Calculate the number of inputs and outputs in BODY, an
728 asm_operands. N_OPERANDS is the total number of operands, and
729 N_INPUTS and N_OUTPUTS are pointers to ints into which the results are
733 get_asm_operand_n_inputs (rtx body)
735 switch (GET_CODE (body))
738 gcc_assert (GET_CODE (SET_SRC (body)) == ASM_OPERANDS);
739 return ASM_OPERANDS_INPUT_LENGTH (SET_SRC (body));
742 return ASM_OPERANDS_INPUT_LENGTH (body);
745 return get_asm_operand_n_inputs (XVECEXP (body, 0, 0));
752 /* If current function returns its result in an fp stack register,
753 return the REG. Otherwise, return 0. */
756 stack_result (tree decl)
760 /* If the value is supposed to be returned in memory, then clearly
761 it is not returned in a stack register. */
762 if (aggregate_value_p (DECL_RESULT (decl), decl))
765 result = DECL_RTL_IF_SET (DECL_RESULT (decl));
768 #ifdef FUNCTION_OUTGOING_VALUE
770 = FUNCTION_OUTGOING_VALUE (TREE_TYPE (DECL_RESULT (decl)), decl);
772 result = FUNCTION_VALUE (TREE_TYPE (DECL_RESULT (decl)), decl);
776 return result != 0 && STACK_REG_P (result) ? result : 0;
781 * This section deals with stack register substitution, and forms the second
785 /* Replace REG, which is a pointer to a stack reg RTX, with an RTX for
786 the desired hard REGNO. */
789 replace_reg (rtx *reg, int regno)
791 gcc_assert (regno >= FIRST_STACK_REG);
792 gcc_assert (regno <= LAST_STACK_REG);
793 gcc_assert (STACK_REG_P (*reg));
795 gcc_assert (GET_MODE_CLASS (GET_MODE (*reg)) == MODE_FLOAT
796 || GET_MODE_CLASS (GET_MODE (*reg)) == MODE_COMPLEX_FLOAT);
798 *reg = FP_MODE_REG (regno, GET_MODE (*reg));
801 /* Remove a note of type NOTE, which must be found, for register
802 number REGNO from INSN. Remove only one such note. */
805 remove_regno_note (rtx insn, enum reg_note note, unsigned int regno)
807 rtx *note_link, this;
809 note_link = ®_NOTES (insn);
810 for (this = *note_link; this; this = XEXP (this, 1))
811 if (REG_NOTE_KIND (this) == note
812 && REG_P (XEXP (this, 0)) && REGNO (XEXP (this, 0)) == regno)
814 *note_link = XEXP (this, 1);
818 note_link = &XEXP (this, 1);
823 /* Find the hard register number of virtual register REG in REGSTACK.
824 The hard register number is relative to the top of the stack. -1 is
825 returned if the register is not found. */
828 get_hard_regnum (stack regstack, rtx reg)
832 gcc_assert (STACK_REG_P (reg));
834 for (i = regstack->top; i >= 0; i--)
835 if (regstack->reg[i] == REGNO (reg))
838 return i >= 0 ? (FIRST_STACK_REG + regstack->top - i) : -1;
841 /* Emit an insn to pop virtual register REG before or after INSN.
842 REGSTACK is the stack state after INSN and is updated to reflect this
843 pop. WHEN is either emit_insn_before or emit_insn_after. A pop insn
844 is represented as a SET whose destination is the register to be popped
845 and source is the top of stack. A death note for the top of stack
846 cases the movdf pattern to pop. */
849 emit_pop_insn (rtx insn, stack regstack, rtx reg, enum emit_where where)
851 rtx pop_insn, pop_rtx;
854 /* For complex types take care to pop both halves. These may survive in
855 CLOBBER and USE expressions. */
856 if (COMPLEX_MODE_P (GET_MODE (reg)))
858 rtx reg1 = FP_MODE_REG (REGNO (reg), DFmode);
859 rtx reg2 = FP_MODE_REG (REGNO (reg) + 1, DFmode);
862 if (get_hard_regnum (regstack, reg1) >= 0)
863 pop_insn = emit_pop_insn (insn, regstack, reg1, where);
864 if (get_hard_regnum (regstack, reg2) >= 0)
865 pop_insn = emit_pop_insn (insn, regstack, reg2, where);
866 gcc_assert (pop_insn);
870 hard_regno = get_hard_regnum (regstack, reg);
872 gcc_assert (hard_regno >= FIRST_STACK_REG);
874 pop_rtx = gen_rtx_SET (VOIDmode, FP_MODE_REG (hard_regno, DFmode),
875 FP_MODE_REG (FIRST_STACK_REG, DFmode));
877 if (where == EMIT_AFTER)
878 pop_insn = emit_insn_after (pop_rtx, insn);
880 pop_insn = emit_insn_before (pop_rtx, insn);
883 = gen_rtx_EXPR_LIST (REG_DEAD, FP_MODE_REG (FIRST_STACK_REG, DFmode),
884 REG_NOTES (pop_insn));
886 regstack->reg[regstack->top - (hard_regno - FIRST_STACK_REG)]
887 = regstack->reg[regstack->top];
889 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (reg));
894 /* Emit an insn before or after INSN to swap virtual register REG with
895 the top of stack. REGSTACK is the stack state before the swap, and
896 is updated to reflect the swap. A swap insn is represented as a
897 PARALLEL of two patterns: each pattern moves one reg to the other.
899 If REG is already at the top of the stack, no insn is emitted. */
902 emit_swap_insn (rtx insn, stack regstack, rtx reg)
906 int tmp, other_reg; /* swap regno temps */
907 rtx i1; /* the stack-reg insn prior to INSN */
908 rtx i1set = NULL_RTX; /* the SET rtx within I1 */
910 hard_regno = get_hard_regnum (regstack, reg);
912 gcc_assert (hard_regno >= FIRST_STACK_REG);
913 if (hard_regno == FIRST_STACK_REG)
916 other_reg = regstack->top - (hard_regno - FIRST_STACK_REG);
918 tmp = regstack->reg[other_reg];
919 regstack->reg[other_reg] = regstack->reg[regstack->top];
920 regstack->reg[regstack->top] = tmp;
922 /* Find the previous insn involving stack regs, but don't pass a
925 if (current_block && insn != BB_HEAD (current_block))
927 rtx tmp = PREV_INSN (insn);
928 rtx limit = PREV_INSN (BB_HEAD (current_block));
933 || NOTE_INSN_BASIC_BLOCK_P (tmp)
935 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
936 || (NONJUMP_INSN_P (tmp)
937 && stack_regs_mentioned (tmp)))
942 tmp = PREV_INSN (tmp);
947 && (i1set = single_set (i1)) != NULL_RTX)
949 rtx i1src = *get_true_reg (&SET_SRC (i1set));
950 rtx i1dest = *get_true_reg (&SET_DEST (i1set));
952 /* If the previous register stack push was from the reg we are to
953 swap with, omit the swap. */
955 if (REG_P (i1dest) && REGNO (i1dest) == FIRST_STACK_REG
957 && REGNO (i1src) == (unsigned) hard_regno - 1
958 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
961 /* If the previous insn wrote to the reg we are to swap with,
964 if (REG_P (i1dest) && REGNO (i1dest) == (unsigned) hard_regno
965 && REG_P (i1src) && REGNO (i1src) == FIRST_STACK_REG
966 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
970 swap_rtx = gen_swapxf (FP_MODE_REG (hard_regno, XFmode),
971 FP_MODE_REG (FIRST_STACK_REG, XFmode));
974 emit_insn_after (swap_rtx, i1);
975 else if (current_block)
976 emit_insn_before (swap_rtx, BB_HEAD (current_block));
978 emit_insn_before (swap_rtx, insn);
981 /* Emit an insns before INSN to swap virtual register SRC1 with
982 the top of stack and virtual register SRC2 with second stack
983 slot. REGSTACK is the stack state before the swaps, and
984 is updated to reflect the swaps. A swap insn is represented as a
985 PARALLEL of two patterns: each pattern moves one reg to the other.
987 If SRC1 and/or SRC2 are already at the right place, no swap insn
991 swap_to_top (rtx insn, stack regstack, rtx src1, rtx src2)
993 struct stack_def temp_stack;
994 int regno, j, k, temp;
996 temp_stack = *regstack;
998 /* Place operand 1 at the top of stack. */
999 regno = get_hard_regnum (&temp_stack, src1);
1000 gcc_assert (regno >= 0);
1001 if (regno != FIRST_STACK_REG)
1003 k = temp_stack.top - (regno - FIRST_STACK_REG);
1006 temp = temp_stack.reg[k];
1007 temp_stack.reg[k] = temp_stack.reg[j];
1008 temp_stack.reg[j] = temp;
1011 /* Place operand 2 next on the stack. */
1012 regno = get_hard_regnum (&temp_stack, src2);
1013 gcc_assert (regno >= 0);
1014 if (regno != FIRST_STACK_REG + 1)
1016 k = temp_stack.top - (regno - FIRST_STACK_REG);
1017 j = temp_stack.top - 1;
1019 temp = temp_stack.reg[k];
1020 temp_stack.reg[k] = temp_stack.reg[j];
1021 temp_stack.reg[j] = temp;
1024 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
1027 /* Handle a move to or from a stack register in PAT, which is in INSN.
1028 REGSTACK is the current stack. Return whether a control flow insn
1029 was deleted in the process. */
1032 move_for_stack_reg (rtx insn, stack regstack, rtx pat)
1034 rtx *psrc = get_true_reg (&SET_SRC (pat));
1035 rtx *pdest = get_true_reg (&SET_DEST (pat));
1038 bool control_flow_insn_deleted = false;
1040 src = *psrc; dest = *pdest;
1042 if (STACK_REG_P (src) && STACK_REG_P (dest))
1044 /* Write from one stack reg to another. If SRC dies here, then
1045 just change the register mapping and delete the insn. */
1047 note = find_regno_note (insn, REG_DEAD, REGNO (src));
1052 /* If this is a no-op move, there must not be a REG_DEAD note. */
1053 gcc_assert (REGNO (src) != REGNO (dest));
1055 for (i = regstack->top; i >= 0; i--)
1056 if (regstack->reg[i] == REGNO (src))
1059 /* The destination must be dead, or life analysis is borked. */
1060 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1062 /* If the source is not live, this is yet another case of
1063 uninitialized variables. Load up a NaN instead. */
1065 return move_nan_for_stack_reg (insn, regstack, dest);
1067 /* It is possible that the dest is unused after this insn.
1068 If so, just pop the src. */
1070 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
1071 emit_pop_insn (insn, regstack, src, EMIT_AFTER);
1074 regstack->reg[i] = REGNO (dest);
1075 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1076 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1079 control_flow_insn_deleted |= control_flow_insn_p (insn);
1081 return control_flow_insn_deleted;
1084 /* The source reg does not die. */
1086 /* If this appears to be a no-op move, delete it, or else it
1087 will confuse the machine description output patterns. But if
1088 it is REG_UNUSED, we must pop the reg now, as per-insn processing
1089 for REG_UNUSED will not work for deleted insns. */
1091 if (REGNO (src) == REGNO (dest))
1093 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
1094 emit_pop_insn (insn, regstack, dest, EMIT_AFTER);
1096 control_flow_insn_deleted |= control_flow_insn_p (insn);
1098 return control_flow_insn_deleted;
1101 /* The destination ought to be dead. */
1102 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1104 replace_reg (psrc, get_hard_regnum (regstack, src));
1106 regstack->reg[++regstack->top] = REGNO (dest);
1107 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1108 replace_reg (pdest, FIRST_STACK_REG);
1110 else if (STACK_REG_P (src))
1112 /* Save from a stack reg to MEM, or possibly integer reg. Since
1113 only top of stack may be saved, emit an exchange first if
1116 emit_swap_insn (insn, regstack, src);
1118 note = find_regno_note (insn, REG_DEAD, REGNO (src));
1121 replace_reg (&XEXP (note, 0), FIRST_STACK_REG);
1123 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1125 else if ((GET_MODE (src) == XFmode)
1126 && regstack->top < REG_STACK_SIZE - 1)
1128 /* A 387 cannot write an XFmode value to a MEM without
1129 clobbering the source reg. The output code can handle
1130 this by reading back the value from the MEM.
1131 But it is more efficient to use a temp register if one is
1132 available. Push the source value here if the register
1133 stack is not full, and then write the value to memory via
1136 rtx top_stack_reg = FP_MODE_REG (FIRST_STACK_REG, GET_MODE (src));
1138 push_rtx = gen_movxf (top_stack_reg, top_stack_reg);
1139 emit_insn_before (push_rtx, insn);
1140 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_DEAD, top_stack_reg,
1144 replace_reg (psrc, FIRST_STACK_REG);
1148 gcc_assert (STACK_REG_P (dest));
1150 /* Load from MEM, or possibly integer REG or constant, into the
1151 stack regs. The actual target is always the top of the
1152 stack. The stack mapping is changed to reflect that DEST is
1153 now at top of stack. */
1155 /* The destination ought to be dead. */
1156 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1158 gcc_assert (regstack->top < REG_STACK_SIZE);
1160 regstack->reg[++regstack->top] = REGNO (dest);
1161 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1162 replace_reg (pdest, FIRST_STACK_REG);
1165 return control_flow_insn_deleted;
1168 /* A helper function which replaces INSN with a pattern that loads up
1169 a NaN into DEST, then invokes move_for_stack_reg. */
1172 move_nan_for_stack_reg (rtx insn, stack regstack, rtx dest)
1176 dest = FP_MODE_REG (REGNO (dest), SFmode);
1177 pat = gen_rtx_SET (VOIDmode, dest, not_a_num);
1178 PATTERN (insn) = pat;
1179 INSN_CODE (insn) = -1;
1181 return move_for_stack_reg (insn, regstack, pat);
1184 /* Swap the condition on a branch, if there is one. Return true if we
1185 found a condition to swap. False if the condition was not used as
1189 swap_rtx_condition_1 (rtx pat)
1194 if (COMPARISON_P (pat))
1196 PUT_CODE (pat, swap_condition (GET_CODE (pat)));
1201 fmt = GET_RTX_FORMAT (GET_CODE (pat));
1202 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
1208 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
1209 r |= swap_rtx_condition_1 (XVECEXP (pat, i, j));
1211 else if (fmt[i] == 'e')
1212 r |= swap_rtx_condition_1 (XEXP (pat, i));
1220 swap_rtx_condition (rtx insn)
1222 rtx pat = PATTERN (insn);
1224 /* We're looking for a single set to cc0 or an HImode temporary. */
1226 if (GET_CODE (pat) == SET
1227 && REG_P (SET_DEST (pat))
1228 && REGNO (SET_DEST (pat)) == FLAGS_REG)
1230 insn = next_flags_user (insn);
1231 if (insn == NULL_RTX)
1233 pat = PATTERN (insn);
1236 /* See if this is, or ends in, a fnstsw, aka unspec 9. If so, we're
1237 not doing anything with the cc value right now. We may be able to
1238 search for one though. */
1240 if (GET_CODE (pat) == SET
1241 && GET_CODE (SET_SRC (pat)) == UNSPEC
1242 && XINT (SET_SRC (pat), 1) == UNSPEC_FNSTSW)
1244 rtx dest = SET_DEST (pat);
1246 /* Search forward looking for the first use of this value.
1247 Stop at block boundaries. */
1248 while (insn != BB_END (current_block))
1250 insn = NEXT_INSN (insn);
1251 if (INSN_P (insn) && reg_mentioned_p (dest, insn))
1257 /* So we've found the insn using this value. If it is anything
1258 other than sahf, aka unspec 10, or the value does not die
1259 (meaning we'd have to search further), then we must give up. */
1260 pat = PATTERN (insn);
1261 if (GET_CODE (pat) != SET
1262 || GET_CODE (SET_SRC (pat)) != UNSPEC
1263 || XINT (SET_SRC (pat), 1) != UNSPEC_SAHF
1264 || ! dead_or_set_p (insn, dest))
1267 /* Now we are prepared to handle this as a normal cc0 setter. */
1268 insn = next_flags_user (insn);
1269 if (insn == NULL_RTX)
1271 pat = PATTERN (insn);
1274 if (swap_rtx_condition_1 (pat))
1277 INSN_CODE (insn) = -1;
1278 if (recog_memoized (insn) == -1)
1280 /* In case the flags don't die here, recurse to try fix
1281 following user too. */
1282 else if (! dead_or_set_p (insn, ix86_flags_rtx))
1284 insn = next_flags_user (insn);
1285 if (!insn || !swap_rtx_condition (insn))
1290 swap_rtx_condition_1 (pat);
1298 /* Handle a comparison. Special care needs to be taken to avoid
1299 causing comparisons that a 387 cannot do correctly, such as EQ.
1301 Also, a pop insn may need to be emitted. The 387 does have an
1302 `fcompp' insn that can pop two regs, but it is sometimes too expensive
1303 to do this - a `fcomp' followed by a `fstpl %st(0)' may be easier to
1307 compare_for_stack_reg (rtx insn, stack regstack, rtx pat_src)
1310 rtx src1_note, src2_note;
1312 src1 = get_true_reg (&XEXP (pat_src, 0));
1313 src2 = get_true_reg (&XEXP (pat_src, 1));
1315 /* ??? If fxch turns out to be cheaper than fstp, give priority to
1316 registers that die in this insn - move those to stack top first. */
1317 if ((! STACK_REG_P (*src1)
1318 || (STACK_REG_P (*src2)
1319 && get_hard_regnum (regstack, *src2) == FIRST_STACK_REG))
1320 && swap_rtx_condition (insn))
1323 temp = XEXP (pat_src, 0);
1324 XEXP (pat_src, 0) = XEXP (pat_src, 1);
1325 XEXP (pat_src, 1) = temp;
1327 src1 = get_true_reg (&XEXP (pat_src, 0));
1328 src2 = get_true_reg (&XEXP (pat_src, 1));
1330 INSN_CODE (insn) = -1;
1333 /* We will fix any death note later. */
1335 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1337 if (STACK_REG_P (*src2))
1338 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1340 src2_note = NULL_RTX;
1342 emit_swap_insn (insn, regstack, *src1);
1344 replace_reg (src1, FIRST_STACK_REG);
1346 if (STACK_REG_P (*src2))
1347 replace_reg (src2, get_hard_regnum (regstack, *src2));
1351 pop_stack (regstack, REGNO (XEXP (src1_note, 0)));
1352 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1355 /* If the second operand dies, handle that. But if the operands are
1356 the same stack register, don't bother, because only one death is
1357 needed, and it was just handled. */
1360 && ! (STACK_REG_P (*src1) && STACK_REG_P (*src2)
1361 && REGNO (*src1) == REGNO (*src2)))
1363 /* As a special case, two regs may die in this insn if src2 is
1364 next to top of stack and the top of stack also dies. Since
1365 we have already popped src1, "next to top of stack" is really
1366 at top (FIRST_STACK_REG) now. */
1368 if (get_hard_regnum (regstack, XEXP (src2_note, 0)) == FIRST_STACK_REG
1371 pop_stack (regstack, REGNO (XEXP (src2_note, 0)));
1372 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1376 /* The 386 can only represent death of the first operand in
1377 the case handled above. In all other cases, emit a separate
1378 pop and remove the death note from here. */
1380 /* link_cc0_insns (insn); */
1382 remove_regno_note (insn, REG_DEAD, REGNO (XEXP (src2_note, 0)));
1384 emit_pop_insn (insn, regstack, XEXP (src2_note, 0),
1390 /* Substitute new registers in PAT, which is part of INSN. REGSTACK
1391 is the current register layout. Return whether a control flow insn
1392 was deleted in the process. */
1395 subst_stack_regs_pat (rtx insn, stack regstack, rtx pat)
1398 bool control_flow_insn_deleted = false;
1400 switch (GET_CODE (pat))
1403 /* Deaths in USE insns can happen in non optimizing compilation.
1404 Handle them by popping the dying register. */
1405 src = get_true_reg (&XEXP (pat, 0));
1406 if (STACK_REG_P (*src)
1407 && find_regno_note (insn, REG_DEAD, REGNO (*src)))
1409 emit_pop_insn (insn, regstack, *src, EMIT_AFTER);
1410 return control_flow_insn_deleted;
1412 /* ??? Uninitialized USE should not happen. */
1414 gcc_assert (get_hard_regnum (regstack, *src) != -1);
1421 dest = get_true_reg (&XEXP (pat, 0));
1422 if (STACK_REG_P (*dest))
1424 note = find_reg_note (insn, REG_DEAD, *dest);
1426 if (pat != PATTERN (insn))
1428 /* The fix_truncdi_1 pattern wants to be able to allocate
1429 it's own scratch register. It does this by clobbering
1430 an fp reg so that it is assured of an empty reg-stack
1431 register. If the register is live, kill it now.
1432 Remove the DEAD/UNUSED note so we don't try to kill it
1436 emit_pop_insn (insn, regstack, *dest, EMIT_BEFORE);
1439 note = find_reg_note (insn, REG_UNUSED, *dest);
1442 remove_note (insn, note);
1443 replace_reg (dest, FIRST_STACK_REG + 1);
1447 /* A top-level clobber with no REG_DEAD, and no hard-regnum
1448 indicates an uninitialized value. Because reload removed
1449 all other clobbers, this must be due to a function
1450 returning without a value. Load up a NaN. */
1455 if (get_hard_regnum (regstack, t) == -1)
1456 control_flow_insn_deleted
1457 |= move_nan_for_stack_reg (insn, regstack, t);
1458 if (COMPLEX_MODE_P (GET_MODE (t)))
1460 t = FP_MODE_REG (REGNO (t) + 1, DFmode);
1461 if (get_hard_regnum (regstack, t) == -1)
1462 control_flow_insn_deleted
1463 |= move_nan_for_stack_reg (insn, regstack, t);
1473 rtx *src1 = (rtx *) 0, *src2;
1474 rtx src1_note, src2_note;
1477 dest = get_true_reg (&SET_DEST (pat));
1478 src = get_true_reg (&SET_SRC (pat));
1479 pat_src = SET_SRC (pat);
1481 /* See if this is a `movM' pattern, and handle elsewhere if so. */
1482 if (STACK_REG_P (*src)
1483 || (STACK_REG_P (*dest)
1484 && (REG_P (*src) || MEM_P (*src)
1485 || GET_CODE (*src) == CONST_DOUBLE)))
1487 control_flow_insn_deleted |= move_for_stack_reg (insn, regstack, pat);
1491 switch (GET_CODE (pat_src))
1494 compare_for_stack_reg (insn, regstack, pat_src);
1500 for (count = hard_regno_nregs[REGNO (*dest)][GET_MODE (*dest)];
1503 regstack->reg[++regstack->top] = REGNO (*dest) + count;
1504 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest) + count);
1507 replace_reg (dest, FIRST_STACK_REG);
1511 /* This is a `tstM2' case. */
1512 gcc_assert (*dest == cc0_rtx);
1517 case FLOAT_TRUNCATE:
1521 /* These insns only operate on the top of the stack. DEST might
1522 be cc0_rtx if we're processing a tstM pattern. Also, it's
1523 possible that the tstM case results in a REG_DEAD note on the
1527 src1 = get_true_reg (&XEXP (pat_src, 0));
1529 emit_swap_insn (insn, regstack, *src1);
1531 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1533 if (STACK_REG_P (*dest))
1534 replace_reg (dest, FIRST_STACK_REG);
1538 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1540 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1543 replace_reg (src1, FIRST_STACK_REG);
1548 /* On i386, reversed forms of subM3 and divM3 exist for
1549 MODE_FLOAT, so the same code that works for addM3 and mulM3
1553 /* These insns can accept the top of stack as a destination
1554 from a stack reg or mem, or can use the top of stack as a
1555 source and some other stack register (possibly top of stack)
1556 as a destination. */
1558 src1 = get_true_reg (&XEXP (pat_src, 0));
1559 src2 = get_true_reg (&XEXP (pat_src, 1));
1561 /* We will fix any death note later. */
1563 if (STACK_REG_P (*src1))
1564 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1566 src1_note = NULL_RTX;
1567 if (STACK_REG_P (*src2))
1568 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1570 src2_note = NULL_RTX;
1572 /* If either operand is not a stack register, then the dest
1573 must be top of stack. */
1575 if (! STACK_REG_P (*src1) || ! STACK_REG_P (*src2))
1576 emit_swap_insn (insn, regstack, *dest);
1579 /* Both operands are REG. If neither operand is already
1580 at the top of stack, choose to make the one that is the dest
1581 the new top of stack. */
1583 int src1_hard_regnum, src2_hard_regnum;
1585 src1_hard_regnum = get_hard_regnum (regstack, *src1);
1586 src2_hard_regnum = get_hard_regnum (regstack, *src2);
1587 gcc_assert (src1_hard_regnum != -1);
1588 gcc_assert (src2_hard_regnum != -1);
1590 if (src1_hard_regnum != FIRST_STACK_REG
1591 && src2_hard_regnum != FIRST_STACK_REG)
1592 emit_swap_insn (insn, regstack, *dest);
1595 if (STACK_REG_P (*src1))
1596 replace_reg (src1, get_hard_regnum (regstack, *src1));
1597 if (STACK_REG_P (*src2))
1598 replace_reg (src2, get_hard_regnum (regstack, *src2));
1602 rtx src1_reg = XEXP (src1_note, 0);
1604 /* If the register that dies is at the top of stack, then
1605 the destination is somewhere else - merely substitute it.
1606 But if the reg that dies is not at top of stack, then
1607 move the top of stack to the dead reg, as though we had
1608 done the insn and then a store-with-pop. */
1610 if (REGNO (src1_reg) == regstack->reg[regstack->top])
1612 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1613 replace_reg (dest, get_hard_regnum (regstack, *dest));
1617 int regno = get_hard_regnum (regstack, src1_reg);
1619 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1620 replace_reg (dest, regno);
1622 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1623 = regstack->reg[regstack->top];
1626 CLEAR_HARD_REG_BIT (regstack->reg_set,
1627 REGNO (XEXP (src1_note, 0)));
1628 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1633 rtx src2_reg = XEXP (src2_note, 0);
1634 if (REGNO (src2_reg) == regstack->reg[regstack->top])
1636 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1637 replace_reg (dest, get_hard_regnum (regstack, *dest));
1641 int regno = get_hard_regnum (regstack, src2_reg);
1643 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1644 replace_reg (dest, regno);
1646 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1647 = regstack->reg[regstack->top];
1650 CLEAR_HARD_REG_BIT (regstack->reg_set,
1651 REGNO (XEXP (src2_note, 0)));
1652 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG);
1657 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1658 replace_reg (dest, get_hard_regnum (regstack, *dest));
1661 /* Keep operand 1 matching with destination. */
1662 if (COMMUTATIVE_ARITH_P (pat_src)
1663 && REG_P (*src1) && REG_P (*src2)
1664 && REGNO (*src1) != REGNO (*dest))
1666 int tmp = REGNO (*src1);
1667 replace_reg (src1, REGNO (*src2));
1668 replace_reg (src2, tmp);
1673 switch (XINT (pat_src, 1))
1676 /* These insns only operate on the top of the stack. */
1678 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1679 emit_swap_insn (insn, regstack, *src1);
1681 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1683 if (STACK_REG_P (*dest))
1684 replace_reg (dest, FIRST_STACK_REG);
1688 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1690 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1693 replace_reg (src1, FIRST_STACK_REG);
1698 case UNSPEC_FRNDINT:
1701 case UNSPEC_FRNDINT_FLOOR:
1702 case UNSPEC_FRNDINT_CEIL:
1703 case UNSPEC_FRNDINT_TRUNC:
1704 case UNSPEC_FRNDINT_MASK_PM:
1706 /* These insns only operate on the top of the stack. */
1708 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1710 emit_swap_insn (insn, regstack, *src1);
1712 /* Input should never die, it is
1713 replaced with output. */
1714 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1715 gcc_assert (!src1_note);
1717 if (STACK_REG_P (*dest))
1718 replace_reg (dest, FIRST_STACK_REG);
1720 replace_reg (src1, FIRST_STACK_REG);
1725 case UNSPEC_FYL2XP1:
1726 /* These insns operate on the top two stack slots. */
1728 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1729 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1731 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1732 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1734 swap_to_top (insn, regstack, *src1, *src2);
1736 replace_reg (src1, FIRST_STACK_REG);
1737 replace_reg (src2, FIRST_STACK_REG + 1);
1740 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1742 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1744 /* Pop both input operands from the stack. */
1745 CLEAR_HARD_REG_BIT (regstack->reg_set,
1746 regstack->reg[regstack->top]);
1747 CLEAR_HARD_REG_BIT (regstack->reg_set,
1748 regstack->reg[regstack->top - 1]);
1751 /* Push the result back onto the stack. */
1752 regstack->reg[++regstack->top] = REGNO (*dest);
1753 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1754 replace_reg (dest, FIRST_STACK_REG);
1757 case UNSPEC_FSCALE_FRACT:
1758 case UNSPEC_FPREM_F:
1759 case UNSPEC_FPREM1_F:
1760 /* These insns operate on the top two stack slots.
1761 first part of double input, double output insn. */
1763 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1764 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1766 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1767 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1769 /* Inputs should never die, they are
1770 replaced with outputs. */
1771 gcc_assert (!src1_note);
1772 gcc_assert (!src2_note);
1774 swap_to_top (insn, regstack, *src1, *src2);
1776 /* Push the result back onto stack. Empty stack slot
1777 will be filled in second part of insn. */
1778 if (STACK_REG_P (*dest)) {
1779 regstack->reg[regstack->top] = REGNO (*dest);
1780 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1781 replace_reg (dest, FIRST_STACK_REG);
1784 replace_reg (src1, FIRST_STACK_REG);
1785 replace_reg (src2, FIRST_STACK_REG + 1);
1788 case UNSPEC_FSCALE_EXP:
1789 case UNSPEC_FPREM_U:
1790 case UNSPEC_FPREM1_U:
1791 /* These insns operate on the top two stack slots./
1792 second part of double input, double output insn. */
1794 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1795 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1797 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1798 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1800 /* Inputs should never die, they are
1801 replaced with outputs. */
1802 gcc_assert (!src1_note);
1803 gcc_assert (!src2_note);
1805 swap_to_top (insn, regstack, *src1, *src2);
1807 /* Push the result back onto stack. Fill empty slot from
1808 first part of insn and fix top of stack pointer. */
1809 if (STACK_REG_P (*dest)) {
1810 regstack->reg[regstack->top - 1] = REGNO (*dest);
1811 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1812 replace_reg (dest, FIRST_STACK_REG + 1);
1815 replace_reg (src1, FIRST_STACK_REG);
1816 replace_reg (src2, FIRST_STACK_REG + 1);
1819 case UNSPEC_SINCOS_COS:
1820 case UNSPEC_TAN_ONE:
1821 case UNSPEC_XTRACT_FRACT:
1822 /* These insns operate on the top two stack slots,
1823 first part of one input, double output insn. */
1825 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1827 emit_swap_insn (insn, regstack, *src1);
1829 /* Input should never die, it is
1830 replaced with output. */
1831 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1832 gcc_assert (!src1_note);
1834 /* Push the result back onto stack. Empty stack slot
1835 will be filled in second part of insn. */
1836 if (STACK_REG_P (*dest)) {
1837 regstack->reg[regstack->top + 1] = REGNO (*dest);
1838 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1839 replace_reg (dest, FIRST_STACK_REG);
1842 replace_reg (src1, FIRST_STACK_REG);
1845 case UNSPEC_SINCOS_SIN:
1846 case UNSPEC_TAN_TAN:
1847 case UNSPEC_XTRACT_EXP:
1848 /* These insns operate on the top two stack slots,
1849 second part of one input, double output insn. */
1851 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1853 emit_swap_insn (insn, regstack, *src1);
1855 /* Input should never die, it is
1856 replaced with output. */
1857 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1858 gcc_assert (!src1_note);
1860 /* Push the result back onto stack. Fill empty slot from
1861 first part of insn and fix top of stack pointer. */
1862 if (STACK_REG_P (*dest)) {
1863 regstack->reg[regstack->top] = REGNO (*dest);
1864 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1865 replace_reg (dest, FIRST_STACK_REG + 1);
1870 replace_reg (src1, FIRST_STACK_REG);
1874 /* (unspec [(unspec [(compare)] UNSPEC_FNSTSW)] UNSPEC_SAHF)
1875 The combination matches the PPRO fcomi instruction. */
1877 pat_src = XVECEXP (pat_src, 0, 0);
1878 gcc_assert (GET_CODE (pat_src) == UNSPEC);
1879 gcc_assert (XINT (pat_src, 1) == UNSPEC_FNSTSW);
1883 /* Combined fcomp+fnstsw generated for doing well with
1884 CSE. When optimizing this would have been broken
1887 pat_src = XVECEXP (pat_src, 0, 0);
1888 gcc_assert (GET_CODE (pat_src) == COMPARE);
1890 compare_for_stack_reg (insn, regstack, pat_src);
1899 /* This insn requires the top of stack to be the destination. */
1901 src1 = get_true_reg (&XEXP (pat_src, 1));
1902 src2 = get_true_reg (&XEXP (pat_src, 2));
1904 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1905 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1907 /* If the comparison operator is an FP comparison operator,
1908 it is handled correctly by compare_for_stack_reg () who
1909 will move the destination to the top of stack. But if the
1910 comparison operator is not an FP comparison operator, we
1911 have to handle it here. */
1912 if (get_hard_regnum (regstack, *dest) >= FIRST_STACK_REG
1913 && REGNO (*dest) != regstack->reg[regstack->top])
1915 /* In case one of operands is the top of stack and the operands
1916 dies, it is safe to make it the destination operand by
1917 reversing the direction of cmove and avoid fxch. */
1918 if ((REGNO (*src1) == regstack->reg[regstack->top]
1920 || (REGNO (*src2) == regstack->reg[regstack->top]
1923 int idx1 = (get_hard_regnum (regstack, *src1)
1925 int idx2 = (get_hard_regnum (regstack, *src2)
1928 /* Make reg-stack believe that the operands are already
1929 swapped on the stack */
1930 regstack->reg[regstack->top - idx1] = REGNO (*src2);
1931 regstack->reg[regstack->top - idx2] = REGNO (*src1);
1933 /* Reverse condition to compensate the operand swap.
1934 i386 do have comparison always reversible. */
1935 PUT_CODE (XEXP (pat_src, 0),
1936 reversed_comparison_code (XEXP (pat_src, 0), insn));
1939 emit_swap_insn (insn, regstack, *dest);
1947 src_note[1] = src1_note;
1948 src_note[2] = src2_note;
1950 if (STACK_REG_P (*src1))
1951 replace_reg (src1, get_hard_regnum (regstack, *src1));
1952 if (STACK_REG_P (*src2))
1953 replace_reg (src2, get_hard_regnum (regstack, *src2));
1955 for (i = 1; i <= 2; i++)
1958 int regno = REGNO (XEXP (src_note[i], 0));
1960 /* If the register that dies is not at the top of
1961 stack, then move the top of stack to the dead reg.
1962 Top of stack should never die, as it is the
1964 gcc_assert (regno != regstack->reg[regstack->top]);
1965 remove_regno_note (insn, REG_DEAD, regno);
1966 emit_pop_insn (insn, regstack, XEXP (src_note[i], 0),
1971 /* Make dest the top of stack. Add dest to regstack if
1973 if (get_hard_regnum (regstack, *dest) < FIRST_STACK_REG)
1974 regstack->reg[++regstack->top] = REGNO (*dest);
1975 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1976 replace_reg (dest, FIRST_STACK_REG);
1989 return control_flow_insn_deleted;
1992 /* Substitute hard regnums for any stack regs in INSN, which has
1993 N_INPUTS inputs and N_OUTPUTS outputs. REGSTACK is the stack info
1994 before the insn, and is updated with changes made here.
1996 There are several requirements and assumptions about the use of
1997 stack-like regs in asm statements. These rules are enforced by
1998 record_asm_stack_regs; see comments there for details. Any
1999 asm_operands left in the RTL at this point may be assume to meet the
2000 requirements, since record_asm_stack_regs removes any problem asm. */
2003 subst_asm_stack_regs (rtx insn, stack regstack)
2005 rtx body = PATTERN (insn);
2008 rtx *note_reg; /* Array of note contents */
2009 rtx **note_loc; /* Address of REG field of each note */
2010 enum reg_note *note_kind; /* The type of each note */
2012 rtx *clobber_reg = 0;
2013 rtx **clobber_loc = 0;
2015 struct stack_def temp_stack;
2020 int n_inputs, n_outputs;
2022 if (! check_asm_stack_operands (insn))
2025 /* Find out what the constraints required. If no constraint
2026 alternative matches, that is a compiler bug: we should have caught
2027 such an insn in check_asm_stack_operands. */
2028 extract_insn (insn);
2029 constrain_operands (1);
2030 alt = which_alternative;
2032 preprocess_constraints ();
2034 n_inputs = get_asm_operand_n_inputs (body);
2035 n_outputs = recog_data.n_operands - n_inputs;
2037 gcc_assert (alt >= 0);
2039 /* Strip SUBREGs here to make the following code simpler. */
2040 for (i = 0; i < recog_data.n_operands; i++)
2041 if (GET_CODE (recog_data.operand[i]) == SUBREG
2042 && REG_P (SUBREG_REG (recog_data.operand[i])))
2044 recog_data.operand_loc[i] = & SUBREG_REG (recog_data.operand[i]);
2045 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
2048 /* Set up NOTE_REG, NOTE_LOC and NOTE_KIND. */
2050 for (i = 0, note = REG_NOTES (insn); note; note = XEXP (note, 1))
2053 note_reg = alloca (i * sizeof (rtx));
2054 note_loc = alloca (i * sizeof (rtx *));
2055 note_kind = alloca (i * sizeof (enum reg_note));
2058 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2060 rtx reg = XEXP (note, 0);
2061 rtx *loc = & XEXP (note, 0);
2063 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
2065 loc = & SUBREG_REG (reg);
2066 reg = SUBREG_REG (reg);
2069 if (STACK_REG_P (reg)
2070 && (REG_NOTE_KIND (note) == REG_DEAD
2071 || REG_NOTE_KIND (note) == REG_UNUSED))
2073 note_reg[n_notes] = reg;
2074 note_loc[n_notes] = loc;
2075 note_kind[n_notes] = REG_NOTE_KIND (note);
2080 /* Set up CLOBBER_REG and CLOBBER_LOC. */
2084 if (GET_CODE (body) == PARALLEL)
2086 clobber_reg = alloca (XVECLEN (body, 0) * sizeof (rtx));
2087 clobber_loc = alloca (XVECLEN (body, 0) * sizeof (rtx *));
2089 for (i = 0; i < XVECLEN (body, 0); i++)
2090 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
2092 rtx clobber = XVECEXP (body, 0, i);
2093 rtx reg = XEXP (clobber, 0);
2094 rtx *loc = & XEXP (clobber, 0);
2096 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
2098 loc = & SUBREG_REG (reg);
2099 reg = SUBREG_REG (reg);
2102 if (STACK_REG_P (reg))
2104 clobber_reg[n_clobbers] = reg;
2105 clobber_loc[n_clobbers] = loc;
2111 temp_stack = *regstack;
2113 /* Put the input regs into the desired place in TEMP_STACK. */
2115 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2116 if (STACK_REG_P (recog_data.operand[i])
2117 && reg_class_subset_p (recog_op_alt[i][alt].cl,
2119 && recog_op_alt[i][alt].cl != FLOAT_REGS)
2121 /* If an operand needs to be in a particular reg in
2122 FLOAT_REGS, the constraint was either 't' or 'u'. Since
2123 these constraints are for single register classes, and
2124 reload guaranteed that operand[i] is already in that class,
2125 we can just use REGNO (recog_data.operand[i]) to know which
2126 actual reg this operand needs to be in. */
2128 int regno = get_hard_regnum (&temp_stack, recog_data.operand[i]);
2130 gcc_assert (regno >= 0);
2132 if ((unsigned int) regno != REGNO (recog_data.operand[i]))
2134 /* recog_data.operand[i] is not in the right place. Find
2135 it and swap it with whatever is already in I's place.
2136 K is where recog_data.operand[i] is now. J is where it
2140 k = temp_stack.top - (regno - FIRST_STACK_REG);
2142 - (REGNO (recog_data.operand[i]) - FIRST_STACK_REG));
2144 temp = temp_stack.reg[k];
2145 temp_stack.reg[k] = temp_stack.reg[j];
2146 temp_stack.reg[j] = temp;
2150 /* Emit insns before INSN to make sure the reg-stack is in the right
2153 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
2155 /* Make the needed input register substitutions. Do death notes and
2156 clobbers too, because these are for inputs, not outputs. */
2158 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2159 if (STACK_REG_P (recog_data.operand[i]))
2161 int regnum = get_hard_regnum (regstack, recog_data.operand[i]);
2163 gcc_assert (regnum >= 0);
2165 replace_reg (recog_data.operand_loc[i], regnum);
2168 for (i = 0; i < n_notes; i++)
2169 if (note_kind[i] == REG_DEAD)
2171 int regnum = get_hard_regnum (regstack, note_reg[i]);
2173 gcc_assert (regnum >= 0);
2175 replace_reg (note_loc[i], regnum);
2178 for (i = 0; i < n_clobbers; i++)
2180 /* It's OK for a CLOBBER to reference a reg that is not live.
2181 Don't try to replace it in that case. */
2182 int regnum = get_hard_regnum (regstack, clobber_reg[i]);
2186 /* Sigh - clobbers always have QImode. But replace_reg knows
2187 that these regs can't be MODE_INT and will assert. Just put
2188 the right reg there without calling replace_reg. */
2190 *clobber_loc[i] = FP_MODE_REG (regnum, DFmode);
2194 /* Now remove from REGSTACK any inputs that the asm implicitly popped. */
2196 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2197 if (STACK_REG_P (recog_data.operand[i]))
2199 /* An input reg is implicitly popped if it is tied to an
2200 output, or if there is a CLOBBER for it. */
2203 for (j = 0; j < n_clobbers; j++)
2204 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
2207 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
2209 /* recog_data.operand[i] might not be at the top of stack.
2210 But that's OK, because all we need to do is pop the
2211 right number of regs off of the top of the reg-stack.
2212 record_asm_stack_regs guaranteed that all implicitly
2213 popped regs were grouped at the top of the reg-stack. */
2215 CLEAR_HARD_REG_BIT (regstack->reg_set,
2216 regstack->reg[regstack->top]);
2221 /* Now add to REGSTACK any outputs that the asm implicitly pushed.
2222 Note that there isn't any need to substitute register numbers.
2223 ??? Explain why this is true. */
2225 for (i = LAST_STACK_REG; i >= FIRST_STACK_REG; i--)
2227 /* See if there is an output for this hard reg. */
2230 for (j = 0; j < n_outputs; j++)
2231 if (STACK_REG_P (recog_data.operand[j])
2232 && REGNO (recog_data.operand[j]) == (unsigned) i)
2234 regstack->reg[++regstack->top] = i;
2235 SET_HARD_REG_BIT (regstack->reg_set, i);
2240 /* Now emit a pop insn for any REG_UNUSED output, or any REG_DEAD
2241 input that the asm didn't implicitly pop. If the asm didn't
2242 implicitly pop an input reg, that reg will still be live.
2244 Note that we can't use find_regno_note here: the register numbers
2245 in the death notes have already been substituted. */
2247 for (i = 0; i < n_outputs; i++)
2248 if (STACK_REG_P (recog_data.operand[i]))
2252 for (j = 0; j < n_notes; j++)
2253 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2254 && note_kind[j] == REG_UNUSED)
2256 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2262 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2263 if (STACK_REG_P (recog_data.operand[i]))
2267 for (j = 0; j < n_notes; j++)
2268 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2269 && note_kind[j] == REG_DEAD
2270 && TEST_HARD_REG_BIT (regstack->reg_set,
2271 REGNO (recog_data.operand[i])))
2273 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2280 /* Substitute stack hard reg numbers for stack virtual registers in
2281 INSN. Non-stack register numbers are not changed. REGSTACK is the
2282 current stack content. Insns may be emitted as needed to arrange the
2283 stack for the 387 based on the contents of the insn. Return whether
2284 a control flow insn was deleted in the process. */
2287 subst_stack_regs (rtx insn, stack regstack)
2289 rtx *note_link, note;
2290 bool control_flow_insn_deleted = false;
2295 int top = regstack->top;
2297 /* If there are any floating point parameters to be passed in
2298 registers for this call, make sure they are in the right
2303 straighten_stack (PREV_INSN (insn), regstack);
2305 /* Now mark the arguments as dead after the call. */
2307 while (regstack->top >= 0)
2309 CLEAR_HARD_REG_BIT (regstack->reg_set, FIRST_STACK_REG + regstack->top);
2315 /* Do the actual substitution if any stack regs are mentioned.
2316 Since we only record whether entire insn mentions stack regs, and
2317 subst_stack_regs_pat only works for patterns that contain stack regs,
2318 we must check each pattern in a parallel here. A call_value_pop could
2321 if (stack_regs_mentioned (insn))
2323 int n_operands = asm_noperands (PATTERN (insn));
2324 if (n_operands >= 0)
2326 /* This insn is an `asm' with operands. Decode the operands,
2327 decide how many are inputs, and do register substitution.
2328 Any REG_UNUSED notes will be handled by subst_asm_stack_regs. */
2330 subst_asm_stack_regs (insn, regstack);
2331 return control_flow_insn_deleted;
2334 if (GET_CODE (PATTERN (insn)) == PARALLEL)
2335 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
2337 if (stack_regs_mentioned_p (XVECEXP (PATTERN (insn), 0, i)))
2339 if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == CLOBBER)
2340 XVECEXP (PATTERN (insn), 0, i)
2341 = shallow_copy_rtx (XVECEXP (PATTERN (insn), 0, i));
2342 control_flow_insn_deleted
2343 |= subst_stack_regs_pat (insn, regstack,
2344 XVECEXP (PATTERN (insn), 0, i));
2348 control_flow_insn_deleted
2349 |= subst_stack_regs_pat (insn, regstack, PATTERN (insn));
2352 /* subst_stack_regs_pat may have deleted a no-op insn. If so, any
2353 REG_UNUSED will already have been dealt with, so just return. */
2355 if (NOTE_P (insn) || INSN_DELETED_P (insn))
2356 return control_flow_insn_deleted;
2358 /* If there is a REG_UNUSED note on a stack register on this insn,
2359 the indicated reg must be popped. The REG_UNUSED note is removed,
2360 since the form of the newly emitted pop insn references the reg,
2361 making it no longer `unset'. */
2363 note_link = ®_NOTES (insn);
2364 for (note = *note_link; note; note = XEXP (note, 1))
2365 if (REG_NOTE_KIND (note) == REG_UNUSED && STACK_REG_P (XEXP (note, 0)))
2367 *note_link = XEXP (note, 1);
2368 insn = emit_pop_insn (insn, regstack, XEXP (note, 0), EMIT_AFTER);
2371 note_link = &XEXP (note, 1);
2373 return control_flow_insn_deleted;
2376 /* Change the organization of the stack so that it fits a new basic
2377 block. Some registers might have to be popped, but there can never be
2378 a register live in the new block that is not now live.
2380 Insert any needed insns before or after INSN, as indicated by
2381 WHERE. OLD is the original stack layout, and NEW is the desired
2382 form. OLD is updated to reflect the code emitted, i.e., it will be
2383 the same as NEW upon return.
2385 This function will not preserve block_end[]. But that information
2386 is no longer needed once this has executed. */
2389 change_stack (rtx insn, stack old, stack new, enum emit_where where)
2394 /* We will be inserting new insns "backwards". If we are to insert
2395 after INSN, find the next insn, and insert before it. */
2397 if (where == EMIT_AFTER)
2399 if (current_block && BB_END (current_block) == insn)
2401 insn = NEXT_INSN (insn);
2404 /* Pop any registers that are not needed in the new block. */
2406 /* If the destination block's stack already has a specified layout
2407 and contains two or more registers, use a more intelligent algorithm
2408 to pop registers that minimizes the number number of fxchs below. */
2411 bool slots[REG_STACK_SIZE];
2412 int pops[REG_STACK_SIZE];
2413 int next, dest, topsrc;
2415 /* First pass to determine the free slots. */
2416 for (reg = 0; reg <= new->top; reg++)
2417 slots[reg] = TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]);
2419 /* Second pass to allocate preferred slots. */
2421 for (reg = old->top; reg > new->top; reg--)
2422 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2425 for (next = 0; next <= new->top; next++)
2426 if (!slots[next] && new->reg[next] == old->reg[reg])
2428 /* If this is a preference for the new top of stack, record
2429 the fact by remembering it's old->reg in topsrc. */
2430 if (next == new->top)
2441 /* Intentionally, avoid placing the top of stack in it's correct
2442 location, if we still need to permute the stack below and we
2443 can usefully place it somewhere else. This is the case if any
2444 slot is still unallocated, in which case we should place the
2445 top of stack there. */
2447 for (reg = 0; reg < new->top; reg++)
2451 slots[new->top] = false;
2456 /* Third pass allocates remaining slots and emits pop insns. */
2458 for (reg = old->top; reg > new->top; reg--)
2463 /* Find next free slot. */
2468 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[dest], DFmode),
2474 /* The following loop attempts to maximize the number of times we
2475 pop the top of the stack, as this permits the use of the faster
2476 ffreep instruction on platforms that support it. */
2480 for (reg = 0; reg <= old->top; reg++)
2481 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2485 while (old->top >= live)
2486 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[old->top]))
2488 while (TEST_HARD_REG_BIT (new->reg_set, old->reg[next]))
2490 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[next], DFmode),
2494 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[old->top], DFmode),
2500 /* If the new block has never been processed, then it can inherit
2501 the old stack order. */
2503 new->top = old->top;
2504 memcpy (new->reg, old->reg, sizeof (new->reg));
2508 /* This block has been entered before, and we must match the
2509 previously selected stack order. */
2511 /* By now, the only difference should be the order of the stack,
2512 not their depth or liveliness. */
2514 GO_IF_HARD_REG_EQUAL (old->reg_set, new->reg_set, win);
2517 gcc_assert (old->top == new->top);
2519 /* If the stack is not empty (new->top != -1), loop here emitting
2520 swaps until the stack is correct.
2522 The worst case number of swaps emitted is N + 2, where N is the
2523 depth of the stack. In some cases, the reg at the top of
2524 stack may be correct, but swapped anyway in order to fix
2525 other regs. But since we never swap any other reg away from
2526 its correct slot, this algorithm will converge. */
2531 /* Swap the reg at top of stack into the position it is
2532 supposed to be in, until the correct top of stack appears. */
2534 while (old->reg[old->top] != new->reg[new->top])
2536 for (reg = new->top; reg >= 0; reg--)
2537 if (new->reg[reg] == old->reg[old->top])
2540 gcc_assert (reg != -1);
2542 emit_swap_insn (insn, old,
2543 FP_MODE_REG (old->reg[reg], DFmode));
2546 /* See if any regs remain incorrect. If so, bring an
2547 incorrect reg to the top of stack, and let the while loop
2550 for (reg = new->top; reg >= 0; reg--)
2551 if (new->reg[reg] != old->reg[reg])
2553 emit_swap_insn (insn, old,
2554 FP_MODE_REG (old->reg[reg], DFmode));
2559 /* At this point there must be no differences. */
2561 for (reg = old->top; reg >= 0; reg--)
2562 gcc_assert (old->reg[reg] == new->reg[reg]);
2566 BB_END (current_block) = PREV_INSN (insn);
2569 /* Print stack configuration. */
2572 print_stack (FILE *file, stack s)
2578 fprintf (file, "uninitialized\n");
2579 else if (s->top == -1)
2580 fprintf (file, "empty\n");
2585 for (i = 0; i <= s->top; ++i)
2586 fprintf (file, "%d ", s->reg[i]);
2587 fputs ("]\n", file);
2591 /* This function was doing life analysis. We now let the regular live
2592 code do it's job, so we only need to check some extra invariants
2593 that reg-stack expects. Primary among these being that all registers
2594 are initialized before use.
2596 The function returns true when code was emitted to CFG edges and
2597 commit_edge_insertions needs to be called. */
2600 convert_regs_entry (void)
2607 FOR_EACH_BB_REVERSE (block)
2609 block_info bi = BLOCK_INFO (block);
2612 /* Set current register status at last instruction `uninitialized'. */
2613 bi->stack_in.top = -2;
2615 /* Copy live_at_end and live_at_start into temporaries. */
2616 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; reg++)
2618 if (REGNO_REG_SET_P (block->global_live_at_end, reg))
2619 SET_HARD_REG_BIT (bi->out_reg_set, reg);
2620 if (REGNO_REG_SET_P (block->global_live_at_start, reg))
2621 SET_HARD_REG_BIT (bi->stack_in.reg_set, reg);
2625 /* Load something into each stack register live at function entry.
2626 Such live registers can be caused by uninitialized variables or
2627 functions not returning values on all paths. In order to keep
2628 the push/pop code happy, and to not scrog the register stack, we
2629 must put something in these registers. Use a QNaN.
2631 Note that we are inserting converted code here. This code is
2632 never seen by the convert_regs pass. */
2634 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2636 basic_block block = e->dest;
2637 block_info bi = BLOCK_INFO (block);
2640 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2641 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2645 bi->stack_in.reg[++top] = reg;
2647 init = gen_rtx_SET (VOIDmode,
2648 FP_MODE_REG (FIRST_STACK_REG, SFmode),
2650 insert_insn_on_edge (init, e);
2654 bi->stack_in.top = top;
2660 /* Construct the desired stack for function exit. This will either
2661 be `empty', or the function return value at top-of-stack. */
2664 convert_regs_exit (void)
2666 int value_reg_low, value_reg_high;
2670 retvalue = stack_result (current_function_decl);
2671 value_reg_low = value_reg_high = -1;
2674 value_reg_low = REGNO (retvalue);
2675 value_reg_high = value_reg_low
2676 + hard_regno_nregs[value_reg_low][GET_MODE (retvalue)] - 1;
2679 output_stack = &BLOCK_INFO (EXIT_BLOCK_PTR)->stack_in;
2680 if (value_reg_low == -1)
2681 output_stack->top = -1;
2686 output_stack->top = value_reg_high - value_reg_low;
2687 for (reg = value_reg_low; reg <= value_reg_high; ++reg)
2689 output_stack->reg[value_reg_high - reg] = reg;
2690 SET_HARD_REG_BIT (output_stack->reg_set, reg);
2695 /* Adjust the stack of this block on exit to match the stack of the
2696 target block, or copy stack info into the stack of the successor
2697 of the successor hasn't been processed yet. */
2699 compensate_edge (edge e, FILE *file)
2701 basic_block block = e->src, target = e->dest;
2702 block_info bi = BLOCK_INFO (block);
2703 struct stack_def regstack, tmpstack;
2704 stack target_stack = &BLOCK_INFO (target)->stack_in;
2707 current_block = block;
2708 regstack = bi->stack_out;
2710 fprintf (file, "Edge %d->%d: ", block->index, target->index);
2712 if (target_stack->top == -2)
2714 /* The target block hasn't had a stack order selected.
2715 We need merely ensure that no pops are needed. */
2716 for (reg = regstack.top; reg >= 0; --reg)
2717 if (!TEST_HARD_REG_BIT (target_stack->reg_set, regstack.reg[reg]))
2723 fprintf (file, "new block; copying stack position\n");
2725 /* change_stack kills values in regstack. */
2726 tmpstack = regstack;
2728 change_stack (BB_END (block), &tmpstack, target_stack, EMIT_AFTER);
2733 fprintf (file, "new block; pops needed\n");
2737 if (target_stack->top == regstack.top)
2739 for (reg = target_stack->top; reg >= 0; --reg)
2740 if (target_stack->reg[reg] != regstack.reg[reg])
2746 fprintf (file, "no changes needed\n");
2753 fprintf (file, "correcting stack to ");
2754 print_stack (file, target_stack);
2758 /* Care for non-call EH edges specially. The normal return path have
2759 values in registers. These will be popped en masse by the unwind
2761 if ((e->flags & (EDGE_EH | EDGE_ABNORMAL_CALL)) == EDGE_EH)
2762 target_stack->top = -1;
2764 /* Other calls may appear to have values live in st(0), but the
2765 abnormal return path will not have actually loaded the values. */
2766 else if (e->flags & EDGE_ABNORMAL_CALL)
2768 /* Assert that the lifetimes are as we expect -- one value
2769 live at st(0) on the end of the source block, and no
2770 values live at the beginning of the destination block. */
2773 CLEAR_HARD_REG_SET (tmp);
2774 GO_IF_HARD_REG_EQUAL (target_stack->reg_set, tmp, eh1);
2778 /* We are sure that there is st(0) live, otherwise we won't compensate.
2779 For complex return values, we may have st(1) live as well. */
2780 SET_HARD_REG_BIT (tmp, FIRST_STACK_REG);
2781 if (TEST_HARD_REG_BIT (regstack.reg_set, FIRST_STACK_REG + 1))
2782 SET_HARD_REG_BIT (tmp, FIRST_STACK_REG + 1);
2783 GO_IF_HARD_REG_EQUAL (regstack.reg_set, tmp, eh2);
2787 target_stack->top = -1;
2790 /* It is better to output directly to the end of the block
2791 instead of to the edge, because emit_swap can do minimal
2792 insn scheduling. We can do this when there is only one
2793 edge out, and it is not abnormal. */
2794 else if (EDGE_COUNT (block->succs) == 1 && !(e->flags & EDGE_ABNORMAL))
2796 /* change_stack kills values in regstack. */
2797 tmpstack = regstack;
2799 change_stack (BB_END (block), &tmpstack, target_stack,
2800 (JUMP_P (BB_END (block))
2801 ? EMIT_BEFORE : EMIT_AFTER));
2807 /* We don't support abnormal edges. Global takes care to
2808 avoid any live register across them, so we should never
2809 have to insert instructions on such edges. */
2810 gcc_assert (!(e->flags & EDGE_ABNORMAL));
2812 current_block = NULL;
2815 /* ??? change_stack needs some point to emit insns after. */
2816 after = emit_note (NOTE_INSN_DELETED);
2818 tmpstack = regstack;
2819 change_stack (after, &tmpstack, target_stack, EMIT_BEFORE);
2824 insert_insn_on_edge (seq, e);
2830 /* Convert stack register references in one block. */
2833 convert_regs_1 (FILE *file, basic_block block)
2835 struct stack_def regstack;
2836 block_info bi = BLOCK_INFO (block);
2839 edge e, beste = NULL;
2840 bool control_flow_insn_deleted = false;
2844 any_malformed_asm = false;
2846 /* Find the edge we will copy stack from. It should be the most frequent
2847 one as it will get cheapest after compensation code is generated,
2848 if multiple such exists, take one with largest count, prefer critical
2849 one (as splitting critical edges is more expensive), or one with lowest
2850 index, to avoid random changes with different orders of the edges. */
2851 FOR_EACH_EDGE (e, ei, block->preds)
2853 if (e->flags & EDGE_DFS_BACK)
2857 else if (EDGE_FREQUENCY (beste) < EDGE_FREQUENCY (e))
2859 else if (EDGE_FREQUENCY (beste) > EDGE_FREQUENCY (e))
2861 else if (beste->count < e->count)
2863 else if (beste->count > e->count)
2865 else if ((EDGE_CRITICAL_P (e) != 0)
2866 != (EDGE_CRITICAL_P (beste) != 0))
2868 if (EDGE_CRITICAL_P (e))
2871 else if (e->src->index < beste->src->index)
2875 /* Initialize stack at block entry. */
2876 if (bi->stack_in.top == -2)
2879 inserted |= compensate_edge (beste, file);
2882 /* No predecessors. Create an arbitrary input stack. */
2885 bi->stack_in.top = -1;
2886 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2887 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2888 bi->stack_in.reg[++bi->stack_in.top] = reg;
2892 /* Entry blocks do have stack already initialized. */
2895 current_block = block;
2899 fprintf (file, "\nBasic block %d\nInput stack: ", block->index);
2900 print_stack (file, &bi->stack_in);
2903 /* Process all insns in this block. Keep track of NEXT so that we
2904 don't process insns emitted while substituting in INSN. */
2905 next = BB_HEAD (block);
2906 regstack = bi->stack_in;
2910 next = NEXT_INSN (insn);
2912 /* Ensure we have not missed a block boundary. */
2914 if (insn == BB_END (block))
2917 /* Don't bother processing unless there is a stack reg
2918 mentioned or if it's a CALL_INSN. */
2919 if (stack_regs_mentioned (insn)
2924 fprintf (file, " insn %d input stack: ",
2926 print_stack (file, ®stack);
2928 control_flow_insn_deleted |= subst_stack_regs (insn, ®stack);
2935 fprintf (file, "Expected live registers [");
2936 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2937 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg))
2938 fprintf (file, " %d", reg);
2939 fprintf (file, " ]\nOutput stack: ");
2940 print_stack (file, ®stack);
2943 insn = BB_END (block);
2945 insn = PREV_INSN (insn);
2947 /* If the function is declared to return a value, but it returns one
2948 in only some cases, some registers might come live here. Emit
2949 necessary moves for them. */
2951 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2953 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg)
2954 && ! TEST_HARD_REG_BIT (regstack.reg_set, reg))
2959 fprintf (file, "Emitting insn initializing reg %d\n", reg);
2961 set = gen_rtx_SET (VOIDmode, FP_MODE_REG (reg, SFmode), not_a_num);
2962 insn = emit_insn_after (set, insn);
2963 control_flow_insn_deleted |= subst_stack_regs (insn, ®stack);
2967 /* Amongst the insns possibly deleted during the substitution process above,
2968 might have been the only trapping insn in the block. We purge the now
2969 possibly dead EH edges here to avoid an ICE from fixup_abnormal_edges,
2970 called at the end of convert_regs. The order in which we process the
2971 blocks ensures that we never delete an already processed edge.
2973 Note that, at this point, the CFG may have been damaged by the emission
2974 of instructions after an abnormal call, which moves the basic block end
2975 (and is the reason why we call fixup_abnormal_edges later). So we must
2976 be sure that the trapping insn has been deleted before trying to purge
2977 dead edges, otherwise we risk purging valid edges.
2979 ??? We are normally supposed not to delete trapping insns, so we pretend
2980 that the insns deleted above don't actually trap. It would have been
2981 better to detect this earlier and avoid creating the EH edge in the first
2982 place, still, but we don't have enough information at that time. */
2984 if (control_flow_insn_deleted)
2985 purge_dead_edges (block);
2987 /* Something failed if the stack lives don't match. If we had malformed
2988 asms, we zapped the instruction itself, but that didn't produce the
2989 same pattern of register kills as before. */
2990 GO_IF_HARD_REG_EQUAL (regstack.reg_set, bi->out_reg_set, win);
2991 gcc_assert (any_malformed_asm);
2993 bi->stack_out = regstack;
2995 /* Compensate the back edges, as those wasn't visited yet. */
2996 FOR_EACH_EDGE (e, ei, block->succs)
2998 if (e->flags & EDGE_DFS_BACK
2999 || (e->dest == EXIT_BLOCK_PTR))
3001 gcc_assert (BLOCK_INFO (e->dest)->done
3002 || e->dest == block);
3003 inserted |= compensate_edge (e, file);
3006 FOR_EACH_EDGE (e, ei, block->preds)
3008 if (e != beste && !(e->flags & EDGE_DFS_BACK)
3009 && e->src != ENTRY_BLOCK_PTR)
3011 gcc_assert (BLOCK_INFO (e->src)->done);
3012 inserted |= compensate_edge (e, file);
3019 /* Convert registers in all blocks reachable from BLOCK. */
3022 convert_regs_2 (FILE *file, basic_block block)
3024 basic_block *stack, *sp;
3027 /* We process the blocks in a top-down manner, in a way such that one block
3028 is only processed after all its predecessors. The number of predecessors
3029 of every block has already been computed. */
3031 stack = xmalloc (sizeof (*stack) * n_basic_blocks);
3044 /* Processing BLOCK is achieved by convert_regs_1, which may purge
3045 some dead EH outgoing edge after the deletion of the trapping
3046 insn inside the block. Since the number of predecessors of
3047 BLOCK's successors was computed based on the initial edge set,
3048 we check the necessity to process some of these successors
3049 before such an edge deletion may happen. However, there is
3050 a pitfall: if BLOCK is the only predecessor of a successor and
3051 the edge between them happens to be deleted, the successor
3052 becomes unreachable and should not be processed. The problem
3053 is that there is no way to preventively detect this case so we
3054 stack the successor in all cases and hand over the task of
3055 fixing up the discrepancy to convert_regs_1. */
3057 FOR_EACH_EDGE (e, ei, block->succs)
3058 if (! (e->flags & EDGE_DFS_BACK))
3060 BLOCK_INFO (e->dest)->predecessors--;
3061 if (!BLOCK_INFO (e->dest)->predecessors)
3065 inserted |= convert_regs_1 (file, block);
3066 BLOCK_INFO (block)->done = 1;
3068 while (sp != stack);
3075 /* Traverse all basic blocks in a function, converting the register
3076 references in each insn from the "flat" register file that gcc uses,
3077 to the stack-like registers the 387 uses. */
3080 convert_regs (FILE *file)
3087 /* Initialize uninitialized registers on function entry. */
3088 inserted = convert_regs_entry ();
3090 /* Construct the desired stack for function exit. */
3091 convert_regs_exit ();
3092 BLOCK_INFO (EXIT_BLOCK_PTR)->done = 1;
3094 /* ??? Future: process inner loops first, and give them arbitrary
3095 initial stacks which emit_swap_insn can modify. This ought to
3096 prevent double fxch that often appears at the head of a loop. */
3098 /* Process all blocks reachable from all entry points. */
3099 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3100 inserted |= convert_regs_2 (file, e->dest);
3102 /* ??? Process all unreachable blocks. Though there's no excuse
3103 for keeping these even when not optimizing. */
3106 block_info bi = BLOCK_INFO (b);
3109 inserted |= convert_regs_2 (file, b);
3111 clear_aux_for_blocks ();
3113 fixup_abnormal_edges ();
3115 commit_edge_insertions ();
3122 #endif /* STACK_REGS */
3124 #include "gt-reg-stack.h"