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, 51 Franklin Street, Fifth Floor, 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 #include "tree-pass.h"
176 /* We use this array to cache info about insns, because otherwise we
177 spend too much time in stack_regs_mentioned_p.
179 Indexed by insn UIDs. A value of zero is uninitialized, one indicates
180 the insn uses stack registers, two indicates the insn does not use
182 static GTY(()) varray_type stack_regs_mentioned_data;
186 #define REG_STACK_SIZE (LAST_STACK_REG - FIRST_STACK_REG + 1)
188 /* This is the basic stack record. TOP is an index into REG[] such
189 that REG[TOP] is the top of stack. If TOP is -1 the stack is empty.
191 If TOP is -2, REG[] is not yet initialized. Stack initialization
192 consists of placing each live reg in array `reg' and setting `top'
195 REG_SET indicates which registers are live. */
197 typedef struct stack_def
199 int top; /* index to top stack element */
200 HARD_REG_SET reg_set; /* set of live registers */
201 unsigned char reg[REG_STACK_SIZE];/* register - stack mapping */
204 /* This is used to carry information about basic blocks. It is
205 attached to the AUX field of the standard CFG block. */
207 typedef struct block_info_def
209 struct stack_def stack_in; /* Input stack configuration. */
210 struct stack_def stack_out; /* Output stack configuration. */
211 HARD_REG_SET out_reg_set; /* Stack regs live on output. */
212 int done; /* True if block already converted. */
213 int predecessors; /* Number of predecessors that need
217 #define BLOCK_INFO(B) ((block_info) (B)->aux)
219 /* Passed to change_stack to indicate where to emit insns. */
226 /* The block we're currently working on. */
227 static basic_block current_block;
229 /* In the current_block, whether we're processing the first register
230 stack or call instruction, i.e. the the regstack is currently the
231 same as BLOCK_INFO(current_block)->stack_in. */
232 static bool starting_stack_p;
234 /* This is the register file for all register after conversion. */
236 FP_mode_reg[LAST_STACK_REG+1-FIRST_STACK_REG][(int) MAX_MACHINE_MODE];
238 #define FP_MODE_REG(regno,mode) \
239 (FP_mode_reg[(regno)-FIRST_STACK_REG][(int) (mode)])
241 /* Used to initialize uninitialized registers. */
242 static rtx not_a_num;
244 /* Forward declarations */
246 static int stack_regs_mentioned_p (rtx pat);
247 static void pop_stack (stack, int);
248 static rtx *get_true_reg (rtx *);
250 static int check_asm_stack_operands (rtx);
251 static int get_asm_operand_n_inputs (rtx);
252 static rtx stack_result (tree);
253 static void replace_reg (rtx *, int);
254 static void remove_regno_note (rtx, enum reg_note, unsigned int);
255 static int get_hard_regnum (stack, rtx);
256 static rtx emit_pop_insn (rtx, stack, rtx, enum emit_where);
257 static void swap_to_top(rtx, stack, rtx, rtx);
258 static bool move_for_stack_reg (rtx, stack, rtx);
259 static bool move_nan_for_stack_reg (rtx, stack, rtx);
260 static int swap_rtx_condition_1 (rtx);
261 static int swap_rtx_condition (rtx);
262 static void compare_for_stack_reg (rtx, stack, rtx);
263 static bool subst_stack_regs_pat (rtx, stack, rtx);
264 static void subst_asm_stack_regs (rtx, stack);
265 static bool subst_stack_regs (rtx, stack);
266 static void change_stack (rtx, stack, stack, enum emit_where);
267 static void print_stack (FILE *, stack);
268 static rtx next_flags_user (rtx);
270 /* Return nonzero if any stack register is mentioned somewhere within PAT. */
273 stack_regs_mentioned_p (rtx pat)
278 if (STACK_REG_P (pat))
281 fmt = GET_RTX_FORMAT (GET_CODE (pat));
282 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
288 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
289 if (stack_regs_mentioned_p (XVECEXP (pat, i, j)))
292 else if (fmt[i] == 'e' && stack_regs_mentioned_p (XEXP (pat, i)))
299 /* Return nonzero if INSN mentions stacked registers, else return zero. */
302 stack_regs_mentioned (rtx insn)
304 unsigned int uid, max;
307 if (! INSN_P (insn) || !stack_regs_mentioned_data)
310 uid = INSN_UID (insn);
311 max = VARRAY_SIZE (stack_regs_mentioned_data);
314 /* Allocate some extra size to avoid too many reallocs, but
315 do not grow too quickly. */
316 max = uid + uid / 20;
317 VARRAY_GROW (stack_regs_mentioned_data, max);
320 test = VARRAY_CHAR (stack_regs_mentioned_data, uid);
323 /* This insn has yet to be examined. Do so now. */
324 test = stack_regs_mentioned_p (PATTERN (insn)) ? 1 : 2;
325 VARRAY_CHAR (stack_regs_mentioned_data, uid) = test;
331 static rtx ix86_flags_rtx;
334 next_flags_user (rtx insn)
336 /* Search forward looking for the first use of this value.
337 Stop at block boundaries. */
339 while (insn != BB_END (current_block))
341 insn = NEXT_INSN (insn);
343 if (INSN_P (insn) && reg_mentioned_p (ix86_flags_rtx, PATTERN (insn)))
352 /* Reorganize the stack into ascending numbers, before this insn. */
355 straighten_stack (rtx insn, stack regstack)
357 struct stack_def temp_stack;
360 /* If there is only a single register on the stack, then the stack is
361 already in increasing order and no reorganization is needed.
363 Similarly if the stack is empty. */
364 if (regstack->top <= 0)
367 COPY_HARD_REG_SET (temp_stack.reg_set, regstack->reg_set);
369 for (top = temp_stack.top = regstack->top; top >= 0; top--)
370 temp_stack.reg[top] = FIRST_STACK_REG + temp_stack.top - top;
372 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
375 /* Pop a register from the stack. */
378 pop_stack (stack regstack, int regno)
380 int top = regstack->top;
382 CLEAR_HARD_REG_BIT (regstack->reg_set, regno);
384 /* If regno was not at the top of stack then adjust stack. */
385 if (regstack->reg [top] != regno)
388 for (i = regstack->top; i >= 0; i--)
389 if (regstack->reg [i] == regno)
392 for (j = i; j < top; j++)
393 regstack->reg [j] = regstack->reg [j + 1];
399 /* Return a pointer to the REG expression within PAT. If PAT is not a
400 REG, possible enclosed by a conversion rtx, return the inner part of
401 PAT that stopped the search. */
404 get_true_reg (rtx *pat)
407 switch (GET_CODE (*pat))
410 /* Eliminate FP subregister accesses in favor of the
411 actual FP register in use. */
414 if (FP_REG_P (subreg = SUBREG_REG (*pat)))
416 int regno_off = subreg_regno_offset (REGNO (subreg),
420 *pat = FP_MODE_REG (REGNO (subreg) + regno_off,
429 pat = & XEXP (*pat, 0);
433 if (!flag_unsafe_math_optimizations)
435 pat = & XEXP (*pat, 0);
440 /* Set if we find any malformed asms in a block. */
441 static bool any_malformed_asm;
443 /* There are many rules that an asm statement for stack-like regs must
444 follow. Those rules are explained at the top of this file: the rule
445 numbers below refer to that explanation. */
448 check_asm_stack_operands (rtx insn)
452 int malformed_asm = 0;
453 rtx body = PATTERN (insn);
455 char reg_used_as_output[FIRST_PSEUDO_REGISTER];
456 char implicitly_dies[FIRST_PSEUDO_REGISTER];
459 rtx *clobber_reg = 0;
460 int n_inputs, n_outputs;
462 /* Find out what the constraints require. If no constraint
463 alternative matches, this asm is malformed. */
465 constrain_operands (1);
466 alt = which_alternative;
468 preprocess_constraints ();
470 n_inputs = get_asm_operand_n_inputs (body);
471 n_outputs = recog_data.n_operands - n_inputs;
476 /* Avoid further trouble with this insn. */
477 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
481 /* Strip SUBREGs here to make the following code simpler. */
482 for (i = 0; i < recog_data.n_operands; i++)
483 if (GET_CODE (recog_data.operand[i]) == SUBREG
484 && REG_P (SUBREG_REG (recog_data.operand[i])))
485 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
487 /* Set up CLOBBER_REG. */
491 if (GET_CODE (body) == PARALLEL)
493 clobber_reg = alloca (XVECLEN (body, 0) * sizeof (rtx));
495 for (i = 0; i < XVECLEN (body, 0); i++)
496 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
498 rtx clobber = XVECEXP (body, 0, i);
499 rtx reg = XEXP (clobber, 0);
501 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
502 reg = SUBREG_REG (reg);
504 if (STACK_REG_P (reg))
506 clobber_reg[n_clobbers] = reg;
512 /* Enforce rule #4: Output operands must specifically indicate which
513 reg an output appears in after an asm. "=f" is not allowed: the
514 operand constraints must select a class with a single reg.
516 Also enforce rule #5: Output operands must start at the top of
517 the reg-stack: output operands may not "skip" a reg. */
519 memset (reg_used_as_output, 0, sizeof (reg_used_as_output));
520 for (i = 0; i < n_outputs; i++)
521 if (STACK_REG_P (recog_data.operand[i]))
523 if (reg_class_size[(int) recog_op_alt[i][alt].cl] != 1)
525 error_for_asm (insn, "output constraint %d must specify a single register", i);
532 for (j = 0; j < n_clobbers; j++)
533 if (REGNO (recog_data.operand[i]) == REGNO (clobber_reg[j]))
535 error_for_asm (insn, "output constraint %d cannot be specified together with \"%s\" clobber",
536 i, reg_names [REGNO (clobber_reg[j])]);
541 reg_used_as_output[REGNO (recog_data.operand[i])] = 1;
546 /* Search for first non-popped reg. */
547 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
548 if (! reg_used_as_output[i])
551 /* If there are any other popped regs, that's an error. */
552 for (; i < LAST_STACK_REG + 1; i++)
553 if (reg_used_as_output[i])
556 if (i != LAST_STACK_REG + 1)
558 error_for_asm (insn, "output regs must be grouped at top of stack");
562 /* Enforce rule #2: All implicitly popped input regs must be closer
563 to the top of the reg-stack than any input that is not implicitly
566 memset (implicitly_dies, 0, sizeof (implicitly_dies));
567 for (i = n_outputs; i < n_outputs + n_inputs; i++)
568 if (STACK_REG_P (recog_data.operand[i]))
570 /* An input reg is implicitly popped if it is tied to an
571 output, or if there is a CLOBBER for it. */
574 for (j = 0; j < n_clobbers; j++)
575 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
578 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
579 implicitly_dies[REGNO (recog_data.operand[i])] = 1;
582 /* Search for first non-popped reg. */
583 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
584 if (! implicitly_dies[i])
587 /* If there are any other popped regs, that's an error. */
588 for (; i < LAST_STACK_REG + 1; i++)
589 if (implicitly_dies[i])
592 if (i != LAST_STACK_REG + 1)
595 "implicitly popped regs must be grouped at top of stack");
599 /* Enforce rule #3: If any input operand uses the "f" constraint, all
600 output constraints must use the "&" earlyclobber.
602 ??? Detect this more deterministically by having constrain_asm_operands
603 record any earlyclobber. */
605 for (i = n_outputs; i < n_outputs + n_inputs; i++)
606 if (recog_op_alt[i][alt].matches == -1)
610 for (j = 0; j < n_outputs; j++)
611 if (operands_match_p (recog_data.operand[j], recog_data.operand[i]))
614 "output operand %d must use %<&%> constraint", j);
621 /* Avoid further trouble with this insn. */
622 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
623 any_malformed_asm = true;
630 /* Calculate the number of inputs and outputs in BODY, an
631 asm_operands. N_OPERANDS is the total number of operands, and
632 N_INPUTS and N_OUTPUTS are pointers to ints into which the results are
636 get_asm_operand_n_inputs (rtx body)
638 switch (GET_CODE (body))
641 gcc_assert (GET_CODE (SET_SRC (body)) == ASM_OPERANDS);
642 return ASM_OPERANDS_INPUT_LENGTH (SET_SRC (body));
645 return ASM_OPERANDS_INPUT_LENGTH (body);
648 return get_asm_operand_n_inputs (XVECEXP (body, 0, 0));
655 /* If current function returns its result in an fp stack register,
656 return the REG. Otherwise, return 0. */
659 stack_result (tree decl)
663 /* If the value is supposed to be returned in memory, then clearly
664 it is not returned in a stack register. */
665 if (aggregate_value_p (DECL_RESULT (decl), decl))
668 result = DECL_RTL_IF_SET (DECL_RESULT (decl));
671 #ifdef FUNCTION_OUTGOING_VALUE
673 = FUNCTION_OUTGOING_VALUE (TREE_TYPE (DECL_RESULT (decl)), decl);
675 result = FUNCTION_VALUE (TREE_TYPE (DECL_RESULT (decl)), decl);
679 return result != 0 && STACK_REG_P (result) ? result : 0;
684 * This section deals with stack register substitution, and forms the second
688 /* Replace REG, which is a pointer to a stack reg RTX, with an RTX for
689 the desired hard REGNO. */
692 replace_reg (rtx *reg, int regno)
694 gcc_assert (regno >= FIRST_STACK_REG);
695 gcc_assert (regno <= LAST_STACK_REG);
696 gcc_assert (STACK_REG_P (*reg));
698 gcc_assert (GET_MODE_CLASS (GET_MODE (*reg)) == MODE_FLOAT
699 || GET_MODE_CLASS (GET_MODE (*reg)) == MODE_COMPLEX_FLOAT);
701 *reg = FP_MODE_REG (regno, GET_MODE (*reg));
704 /* Remove a note of type NOTE, which must be found, for register
705 number REGNO from INSN. Remove only one such note. */
708 remove_regno_note (rtx insn, enum reg_note note, unsigned int regno)
710 rtx *note_link, this;
712 note_link = ®_NOTES (insn);
713 for (this = *note_link; this; this = XEXP (this, 1))
714 if (REG_NOTE_KIND (this) == note
715 && REG_P (XEXP (this, 0)) && REGNO (XEXP (this, 0)) == regno)
717 *note_link = XEXP (this, 1);
721 note_link = &XEXP (this, 1);
726 /* Find the hard register number of virtual register REG in REGSTACK.
727 The hard register number is relative to the top of the stack. -1 is
728 returned if the register is not found. */
731 get_hard_regnum (stack regstack, rtx reg)
735 gcc_assert (STACK_REG_P (reg));
737 for (i = regstack->top; i >= 0; i--)
738 if (regstack->reg[i] == REGNO (reg))
741 return i >= 0 ? (FIRST_STACK_REG + regstack->top - i) : -1;
744 /* Emit an insn to pop virtual register REG before or after INSN.
745 REGSTACK is the stack state after INSN and is updated to reflect this
746 pop. WHEN is either emit_insn_before or emit_insn_after. A pop insn
747 is represented as a SET whose destination is the register to be popped
748 and source is the top of stack. A death note for the top of stack
749 cases the movdf pattern to pop. */
752 emit_pop_insn (rtx insn, stack regstack, rtx reg, enum emit_where where)
754 rtx pop_insn, pop_rtx;
757 /* For complex types take care to pop both halves. These may survive in
758 CLOBBER and USE expressions. */
759 if (COMPLEX_MODE_P (GET_MODE (reg)))
761 rtx reg1 = FP_MODE_REG (REGNO (reg), DFmode);
762 rtx reg2 = FP_MODE_REG (REGNO (reg) + 1, DFmode);
765 if (get_hard_regnum (regstack, reg1) >= 0)
766 pop_insn = emit_pop_insn (insn, regstack, reg1, where);
767 if (get_hard_regnum (regstack, reg2) >= 0)
768 pop_insn = emit_pop_insn (insn, regstack, reg2, where);
769 gcc_assert (pop_insn);
773 hard_regno = get_hard_regnum (regstack, reg);
775 gcc_assert (hard_regno >= FIRST_STACK_REG);
777 pop_rtx = gen_rtx_SET (VOIDmode, FP_MODE_REG (hard_regno, DFmode),
778 FP_MODE_REG (FIRST_STACK_REG, DFmode));
780 if (where == EMIT_AFTER)
781 pop_insn = emit_insn_after (pop_rtx, insn);
783 pop_insn = emit_insn_before (pop_rtx, insn);
786 = gen_rtx_EXPR_LIST (REG_DEAD, FP_MODE_REG (FIRST_STACK_REG, DFmode),
787 REG_NOTES (pop_insn));
789 regstack->reg[regstack->top - (hard_regno - FIRST_STACK_REG)]
790 = regstack->reg[regstack->top];
792 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (reg));
797 /* Emit an insn before or after INSN to swap virtual register REG with
798 the top of stack. REGSTACK is the stack state before the swap, and
799 is updated to reflect the swap. A swap insn is represented as a
800 PARALLEL of two patterns: each pattern moves one reg to the other.
802 If REG is already at the top of the stack, no insn is emitted. */
805 emit_swap_insn (rtx insn, stack regstack, rtx reg)
809 int tmp, other_reg; /* swap regno temps */
810 rtx i1; /* the stack-reg insn prior to INSN */
811 rtx i1set = NULL_RTX; /* the SET rtx within I1 */
813 hard_regno = get_hard_regnum (regstack, reg);
815 gcc_assert (hard_regno >= FIRST_STACK_REG);
816 if (hard_regno == FIRST_STACK_REG)
819 other_reg = regstack->top - (hard_regno - FIRST_STACK_REG);
821 tmp = regstack->reg[other_reg];
822 regstack->reg[other_reg] = regstack->reg[regstack->top];
823 regstack->reg[regstack->top] = tmp;
825 /* Find the previous insn involving stack regs, but don't pass a
828 if (current_block && insn != BB_HEAD (current_block))
830 rtx tmp = PREV_INSN (insn);
831 rtx limit = PREV_INSN (BB_HEAD (current_block));
836 || NOTE_INSN_BASIC_BLOCK_P (tmp)
837 || (NONJUMP_INSN_P (tmp)
838 && stack_regs_mentioned (tmp)))
843 tmp = PREV_INSN (tmp);
848 && (i1set = single_set (i1)) != NULL_RTX)
850 rtx i1src = *get_true_reg (&SET_SRC (i1set));
851 rtx i1dest = *get_true_reg (&SET_DEST (i1set));
853 /* If the previous register stack push was from the reg we are to
854 swap with, omit the swap. */
856 if (REG_P (i1dest) && REGNO (i1dest) == FIRST_STACK_REG
858 && REGNO (i1src) == (unsigned) hard_regno - 1
859 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
862 /* If the previous insn wrote to the reg we are to swap with,
865 if (REG_P (i1dest) && REGNO (i1dest) == (unsigned) hard_regno
866 && REG_P (i1src) && REGNO (i1src) == FIRST_STACK_REG
867 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
871 /* Avoid emitting the swap if this is the first register stack insn
872 of the current_block. Instead update the current_block's stack_in
873 and let compensate edges take care of this for us. */
874 if (current_block && starting_stack_p)
876 BLOCK_INFO (current_block)->stack_in = *regstack;
877 starting_stack_p = false;
881 swap_rtx = gen_swapxf (FP_MODE_REG (hard_regno, XFmode),
882 FP_MODE_REG (FIRST_STACK_REG, XFmode));
885 emit_insn_after (swap_rtx, i1);
886 else if (current_block)
887 emit_insn_before (swap_rtx, BB_HEAD (current_block));
889 emit_insn_before (swap_rtx, insn);
892 /* Emit an insns before INSN to swap virtual register SRC1 with
893 the top of stack and virtual register SRC2 with second stack
894 slot. REGSTACK is the stack state before the swaps, and
895 is updated to reflect the swaps. A swap insn is represented as a
896 PARALLEL of two patterns: each pattern moves one reg to the other.
898 If SRC1 and/or SRC2 are already at the right place, no swap insn
902 swap_to_top (rtx insn, stack regstack, rtx src1, rtx src2)
904 struct stack_def temp_stack;
905 int regno, j, k, temp;
907 temp_stack = *regstack;
909 /* Place operand 1 at the top of stack. */
910 regno = get_hard_regnum (&temp_stack, src1);
911 gcc_assert (regno >= 0);
912 if (regno != FIRST_STACK_REG)
914 k = temp_stack.top - (regno - FIRST_STACK_REG);
917 temp = temp_stack.reg[k];
918 temp_stack.reg[k] = temp_stack.reg[j];
919 temp_stack.reg[j] = temp;
922 /* Place operand 2 next on the stack. */
923 regno = get_hard_regnum (&temp_stack, src2);
924 gcc_assert (regno >= 0);
925 if (regno != FIRST_STACK_REG + 1)
927 k = temp_stack.top - (regno - FIRST_STACK_REG);
928 j = temp_stack.top - 1;
930 temp = temp_stack.reg[k];
931 temp_stack.reg[k] = temp_stack.reg[j];
932 temp_stack.reg[j] = temp;
935 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
938 /* Handle a move to or from a stack register in PAT, which is in INSN.
939 REGSTACK is the current stack. Return whether a control flow insn
940 was deleted in the process. */
943 move_for_stack_reg (rtx insn, stack regstack, rtx pat)
945 rtx *psrc = get_true_reg (&SET_SRC (pat));
946 rtx *pdest = get_true_reg (&SET_DEST (pat));
949 bool control_flow_insn_deleted = false;
951 src = *psrc; dest = *pdest;
953 if (STACK_REG_P (src) && STACK_REG_P (dest))
955 /* Write from one stack reg to another. If SRC dies here, then
956 just change the register mapping and delete the insn. */
958 note = find_regno_note (insn, REG_DEAD, REGNO (src));
963 /* If this is a no-op move, there must not be a REG_DEAD note. */
964 gcc_assert (REGNO (src) != REGNO (dest));
966 for (i = regstack->top; i >= 0; i--)
967 if (regstack->reg[i] == REGNO (src))
970 /* The destination must be dead, or life analysis is borked. */
971 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
973 /* If the source is not live, this is yet another case of
974 uninitialized variables. Load up a NaN instead. */
976 return move_nan_for_stack_reg (insn, regstack, dest);
978 /* It is possible that the dest is unused after this insn.
979 If so, just pop the src. */
981 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
982 emit_pop_insn (insn, regstack, src, EMIT_AFTER);
985 regstack->reg[i] = REGNO (dest);
986 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
987 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
990 control_flow_insn_deleted |= control_flow_insn_p (insn);
992 return control_flow_insn_deleted;
995 /* The source reg does not die. */
997 /* If this appears to be a no-op move, delete it, or else it
998 will confuse the machine description output patterns. But if
999 it is REG_UNUSED, we must pop the reg now, as per-insn processing
1000 for REG_UNUSED will not work for deleted insns. */
1002 if (REGNO (src) == REGNO (dest))
1004 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
1005 emit_pop_insn (insn, regstack, dest, EMIT_AFTER);
1007 control_flow_insn_deleted |= control_flow_insn_p (insn);
1009 return control_flow_insn_deleted;
1012 /* The destination ought to be dead. */
1013 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1015 replace_reg (psrc, get_hard_regnum (regstack, src));
1017 regstack->reg[++regstack->top] = REGNO (dest);
1018 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1019 replace_reg (pdest, FIRST_STACK_REG);
1021 else if (STACK_REG_P (src))
1023 /* Save from a stack reg to MEM, or possibly integer reg. Since
1024 only top of stack may be saved, emit an exchange first if
1027 emit_swap_insn (insn, regstack, src);
1029 note = find_regno_note (insn, REG_DEAD, REGNO (src));
1032 replace_reg (&XEXP (note, 0), FIRST_STACK_REG);
1034 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1036 else if ((GET_MODE (src) == XFmode)
1037 && regstack->top < REG_STACK_SIZE - 1)
1039 /* A 387 cannot write an XFmode value to a MEM without
1040 clobbering the source reg. The output code can handle
1041 this by reading back the value from the MEM.
1042 But it is more efficient to use a temp register if one is
1043 available. Push the source value here if the register
1044 stack is not full, and then write the value to memory via
1047 rtx top_stack_reg = FP_MODE_REG (FIRST_STACK_REG, GET_MODE (src));
1049 push_rtx = gen_movxf (top_stack_reg, top_stack_reg);
1050 emit_insn_before (push_rtx, insn);
1051 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_DEAD, top_stack_reg,
1055 replace_reg (psrc, FIRST_STACK_REG);
1059 gcc_assert (STACK_REG_P (dest));
1061 /* Load from MEM, or possibly integer REG or constant, into the
1062 stack regs. The actual target is always the top of the
1063 stack. The stack mapping is changed to reflect that DEST is
1064 now at top of stack. */
1066 /* The destination ought to be dead. */
1067 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1069 gcc_assert (regstack->top < REG_STACK_SIZE);
1071 regstack->reg[++regstack->top] = REGNO (dest);
1072 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1073 replace_reg (pdest, FIRST_STACK_REG);
1076 return control_flow_insn_deleted;
1079 /* A helper function which replaces INSN with a pattern that loads up
1080 a NaN into DEST, then invokes move_for_stack_reg. */
1083 move_nan_for_stack_reg (rtx insn, stack regstack, rtx dest)
1087 dest = FP_MODE_REG (REGNO (dest), SFmode);
1088 pat = gen_rtx_SET (VOIDmode, dest, not_a_num);
1089 PATTERN (insn) = pat;
1090 INSN_CODE (insn) = -1;
1092 return move_for_stack_reg (insn, regstack, pat);
1095 /* Swap the condition on a branch, if there is one. Return true if we
1096 found a condition to swap. False if the condition was not used as
1100 swap_rtx_condition_1 (rtx pat)
1105 if (COMPARISON_P (pat))
1107 PUT_CODE (pat, swap_condition (GET_CODE (pat)));
1112 fmt = GET_RTX_FORMAT (GET_CODE (pat));
1113 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
1119 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
1120 r |= swap_rtx_condition_1 (XVECEXP (pat, i, j));
1122 else if (fmt[i] == 'e')
1123 r |= swap_rtx_condition_1 (XEXP (pat, i));
1131 swap_rtx_condition (rtx insn)
1133 rtx pat = PATTERN (insn);
1135 /* We're looking for a single set to cc0 or an HImode temporary. */
1137 if (GET_CODE (pat) == SET
1138 && REG_P (SET_DEST (pat))
1139 && REGNO (SET_DEST (pat)) == FLAGS_REG)
1141 insn = next_flags_user (insn);
1142 if (insn == NULL_RTX)
1144 pat = PATTERN (insn);
1147 /* See if this is, or ends in, a fnstsw. If so, we're not doing anything
1148 with the cc value right now. We may be able to search for one
1151 if (GET_CODE (pat) == SET
1152 && GET_CODE (SET_SRC (pat)) == UNSPEC
1153 && XINT (SET_SRC (pat), 1) == UNSPEC_FNSTSW)
1155 rtx dest = SET_DEST (pat);
1157 /* Search forward looking for the first use of this value.
1158 Stop at block boundaries. */
1159 while (insn != BB_END (current_block))
1161 insn = NEXT_INSN (insn);
1162 if (INSN_P (insn) && reg_mentioned_p (dest, insn))
1168 /* We haven't found it. */
1169 if (insn == BB_END (current_block))
1172 /* So we've found the insn using this value. If it is anything
1173 other than sahf or the value does not die (meaning we'd have
1174 to search further), then we must give up. */
1175 pat = PATTERN (insn);
1176 if (GET_CODE (pat) != SET
1177 || GET_CODE (SET_SRC (pat)) != UNSPEC
1178 || XINT (SET_SRC (pat), 1) != UNSPEC_SAHF
1179 || ! dead_or_set_p (insn, dest))
1182 /* Now we are prepared to handle this as a normal cc0 setter. */
1183 insn = next_flags_user (insn);
1184 if (insn == NULL_RTX)
1186 pat = PATTERN (insn);
1189 if (swap_rtx_condition_1 (pat))
1192 INSN_CODE (insn) = -1;
1193 if (recog_memoized (insn) == -1)
1195 /* In case the flags don't die here, recurse to try fix
1196 following user too. */
1197 else if (! dead_or_set_p (insn, ix86_flags_rtx))
1199 insn = next_flags_user (insn);
1200 if (!insn || !swap_rtx_condition (insn))
1205 swap_rtx_condition_1 (pat);
1213 /* Handle a comparison. Special care needs to be taken to avoid
1214 causing comparisons that a 387 cannot do correctly, such as EQ.
1216 Also, a pop insn may need to be emitted. The 387 does have an
1217 `fcompp' insn that can pop two regs, but it is sometimes too expensive
1218 to do this - a `fcomp' followed by a `fstpl %st(0)' may be easier to
1222 compare_for_stack_reg (rtx insn, stack regstack, rtx pat_src)
1225 rtx src1_note, src2_note;
1227 src1 = get_true_reg (&XEXP (pat_src, 0));
1228 src2 = get_true_reg (&XEXP (pat_src, 1));
1230 /* ??? If fxch turns out to be cheaper than fstp, give priority to
1231 registers that die in this insn - move those to stack top first. */
1232 if ((! STACK_REG_P (*src1)
1233 || (STACK_REG_P (*src2)
1234 && get_hard_regnum (regstack, *src2) == FIRST_STACK_REG))
1235 && swap_rtx_condition (insn))
1238 temp = XEXP (pat_src, 0);
1239 XEXP (pat_src, 0) = XEXP (pat_src, 1);
1240 XEXP (pat_src, 1) = temp;
1242 src1 = get_true_reg (&XEXP (pat_src, 0));
1243 src2 = get_true_reg (&XEXP (pat_src, 1));
1245 INSN_CODE (insn) = -1;
1248 /* We will fix any death note later. */
1250 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1252 if (STACK_REG_P (*src2))
1253 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1255 src2_note = NULL_RTX;
1257 emit_swap_insn (insn, regstack, *src1);
1259 replace_reg (src1, FIRST_STACK_REG);
1261 if (STACK_REG_P (*src2))
1262 replace_reg (src2, get_hard_regnum (regstack, *src2));
1266 pop_stack (regstack, REGNO (XEXP (src1_note, 0)));
1267 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1270 /* If the second operand dies, handle that. But if the operands are
1271 the same stack register, don't bother, because only one death is
1272 needed, and it was just handled. */
1275 && ! (STACK_REG_P (*src1) && STACK_REG_P (*src2)
1276 && REGNO (*src1) == REGNO (*src2)))
1278 /* As a special case, two regs may die in this insn if src2 is
1279 next to top of stack and the top of stack also dies. Since
1280 we have already popped src1, "next to top of stack" is really
1281 at top (FIRST_STACK_REG) now. */
1283 if (get_hard_regnum (regstack, XEXP (src2_note, 0)) == FIRST_STACK_REG
1286 pop_stack (regstack, REGNO (XEXP (src2_note, 0)));
1287 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1291 /* The 386 can only represent death of the first operand in
1292 the case handled above. In all other cases, emit a separate
1293 pop and remove the death note from here. */
1295 /* link_cc0_insns (insn); */
1297 remove_regno_note (insn, REG_DEAD, REGNO (XEXP (src2_note, 0)));
1299 emit_pop_insn (insn, regstack, XEXP (src2_note, 0),
1305 /* Substitute new registers in PAT, which is part of INSN. REGSTACK
1306 is the current register layout. Return whether a control flow insn
1307 was deleted in the process. */
1310 subst_stack_regs_pat (rtx insn, stack regstack, rtx pat)
1313 bool control_flow_insn_deleted = false;
1315 switch (GET_CODE (pat))
1318 /* Deaths in USE insns can happen in non optimizing compilation.
1319 Handle them by popping the dying register. */
1320 src = get_true_reg (&XEXP (pat, 0));
1321 if (STACK_REG_P (*src)
1322 && find_regno_note (insn, REG_DEAD, REGNO (*src)))
1324 emit_pop_insn (insn, regstack, *src, EMIT_AFTER);
1325 return control_flow_insn_deleted;
1327 /* ??? Uninitialized USE should not happen. */
1329 gcc_assert (get_hard_regnum (regstack, *src) != -1);
1336 dest = get_true_reg (&XEXP (pat, 0));
1337 if (STACK_REG_P (*dest))
1339 note = find_reg_note (insn, REG_DEAD, *dest);
1341 if (pat != PATTERN (insn))
1343 /* The fix_truncdi_1 pattern wants to be able to allocate
1344 its own scratch register. It does this by clobbering
1345 an fp reg so that it is assured of an empty reg-stack
1346 register. If the register is live, kill it now.
1347 Remove the DEAD/UNUSED note so we don't try to kill it
1351 emit_pop_insn (insn, regstack, *dest, EMIT_BEFORE);
1354 note = find_reg_note (insn, REG_UNUSED, *dest);
1357 remove_note (insn, note);
1358 replace_reg (dest, FIRST_STACK_REG + 1);
1362 /* A top-level clobber with no REG_DEAD, and no hard-regnum
1363 indicates an uninitialized value. Because reload removed
1364 all other clobbers, this must be due to a function
1365 returning without a value. Load up a NaN. */
1370 if (get_hard_regnum (regstack, t) == -1)
1371 control_flow_insn_deleted
1372 |= move_nan_for_stack_reg (insn, regstack, t);
1373 if (COMPLEX_MODE_P (GET_MODE (t)))
1375 t = FP_MODE_REG (REGNO (t) + 1, DFmode);
1376 if (get_hard_regnum (regstack, t) == -1)
1377 control_flow_insn_deleted
1378 |= move_nan_for_stack_reg (insn, regstack, t);
1388 rtx *src1 = (rtx *) 0, *src2;
1389 rtx src1_note, src2_note;
1392 dest = get_true_reg (&SET_DEST (pat));
1393 src = get_true_reg (&SET_SRC (pat));
1394 pat_src = SET_SRC (pat);
1396 /* See if this is a `movM' pattern, and handle elsewhere if so. */
1397 if (STACK_REG_P (*src)
1398 || (STACK_REG_P (*dest)
1399 && (REG_P (*src) || MEM_P (*src)
1400 || GET_CODE (*src) == CONST_DOUBLE)))
1402 control_flow_insn_deleted |= move_for_stack_reg (insn, regstack, pat);
1406 switch (GET_CODE (pat_src))
1409 compare_for_stack_reg (insn, regstack, pat_src);
1415 for (count = hard_regno_nregs[REGNO (*dest)][GET_MODE (*dest)];
1418 regstack->reg[++regstack->top] = REGNO (*dest) + count;
1419 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest) + count);
1422 replace_reg (dest, FIRST_STACK_REG);
1426 /* This is a `tstM2' case. */
1427 gcc_assert (*dest == cc0_rtx);
1432 case FLOAT_TRUNCATE:
1436 /* These insns only operate on the top of the stack. DEST might
1437 be cc0_rtx if we're processing a tstM pattern. Also, it's
1438 possible that the tstM case results in a REG_DEAD note on the
1442 src1 = get_true_reg (&XEXP (pat_src, 0));
1444 emit_swap_insn (insn, regstack, *src1);
1446 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1448 if (STACK_REG_P (*dest))
1449 replace_reg (dest, FIRST_STACK_REG);
1453 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1455 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1458 replace_reg (src1, FIRST_STACK_REG);
1463 /* On i386, reversed forms of subM3 and divM3 exist for
1464 MODE_FLOAT, so the same code that works for addM3 and mulM3
1468 /* These insns can accept the top of stack as a destination
1469 from a stack reg or mem, or can use the top of stack as a
1470 source and some other stack register (possibly top of stack)
1471 as a destination. */
1473 src1 = get_true_reg (&XEXP (pat_src, 0));
1474 src2 = get_true_reg (&XEXP (pat_src, 1));
1476 /* We will fix any death note later. */
1478 if (STACK_REG_P (*src1))
1479 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1481 src1_note = NULL_RTX;
1482 if (STACK_REG_P (*src2))
1483 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1485 src2_note = NULL_RTX;
1487 /* If either operand is not a stack register, then the dest
1488 must be top of stack. */
1490 if (! STACK_REG_P (*src1) || ! STACK_REG_P (*src2))
1491 emit_swap_insn (insn, regstack, *dest);
1494 /* Both operands are REG. If neither operand is already
1495 at the top of stack, choose to make the one that is the dest
1496 the new top of stack. */
1498 int src1_hard_regnum, src2_hard_regnum;
1500 src1_hard_regnum = get_hard_regnum (regstack, *src1);
1501 src2_hard_regnum = get_hard_regnum (regstack, *src2);
1502 gcc_assert (src1_hard_regnum != -1);
1503 gcc_assert (src2_hard_regnum != -1);
1505 if (src1_hard_regnum != FIRST_STACK_REG
1506 && src2_hard_regnum != FIRST_STACK_REG)
1507 emit_swap_insn (insn, regstack, *dest);
1510 if (STACK_REG_P (*src1))
1511 replace_reg (src1, get_hard_regnum (regstack, *src1));
1512 if (STACK_REG_P (*src2))
1513 replace_reg (src2, get_hard_regnum (regstack, *src2));
1517 rtx src1_reg = XEXP (src1_note, 0);
1519 /* If the register that dies is at the top of stack, then
1520 the destination is somewhere else - merely substitute it.
1521 But if the reg that dies is not at top of stack, then
1522 move the top of stack to the dead reg, as though we had
1523 done the insn and then a store-with-pop. */
1525 if (REGNO (src1_reg) == regstack->reg[regstack->top])
1527 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1528 replace_reg (dest, get_hard_regnum (regstack, *dest));
1532 int regno = get_hard_regnum (regstack, src1_reg);
1534 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1535 replace_reg (dest, regno);
1537 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1538 = regstack->reg[regstack->top];
1541 CLEAR_HARD_REG_BIT (regstack->reg_set,
1542 REGNO (XEXP (src1_note, 0)));
1543 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1548 rtx src2_reg = XEXP (src2_note, 0);
1549 if (REGNO (src2_reg) == regstack->reg[regstack->top])
1551 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1552 replace_reg (dest, get_hard_regnum (regstack, *dest));
1556 int regno = get_hard_regnum (regstack, src2_reg);
1558 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1559 replace_reg (dest, regno);
1561 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1562 = regstack->reg[regstack->top];
1565 CLEAR_HARD_REG_BIT (regstack->reg_set,
1566 REGNO (XEXP (src2_note, 0)));
1567 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG);
1572 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1573 replace_reg (dest, get_hard_regnum (regstack, *dest));
1576 /* Keep operand 1 matching with destination. */
1577 if (COMMUTATIVE_ARITH_P (pat_src)
1578 && REG_P (*src1) && REG_P (*src2)
1579 && REGNO (*src1) != REGNO (*dest))
1581 int tmp = REGNO (*src1);
1582 replace_reg (src1, REGNO (*src2));
1583 replace_reg (src2, tmp);
1588 switch (XINT (pat_src, 1))
1592 case UNSPEC_FIST_FLOOR:
1593 case UNSPEC_FIST_CEIL:
1595 /* These insns only operate on the top of the stack. */
1597 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1598 emit_swap_insn (insn, regstack, *src1);
1600 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1602 if (STACK_REG_P (*dest))
1603 replace_reg (dest, FIRST_STACK_REG);
1607 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1609 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1612 replace_reg (src1, FIRST_STACK_REG);
1617 case UNSPEC_FRNDINT:
1620 case UNSPEC_FRNDINT_FLOOR:
1621 case UNSPEC_FRNDINT_CEIL:
1622 case UNSPEC_FRNDINT_TRUNC:
1623 case UNSPEC_FRNDINT_MASK_PM:
1625 /* These insns only operate on the top of the stack. */
1627 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1629 emit_swap_insn (insn, regstack, *src1);
1631 /* Input should never die, it is
1632 replaced with output. */
1633 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1634 gcc_assert (!src1_note);
1636 if (STACK_REG_P (*dest))
1637 replace_reg (dest, FIRST_STACK_REG);
1639 replace_reg (src1, FIRST_STACK_REG);
1644 case UNSPEC_FYL2XP1:
1645 /* These insns operate on the top two stack slots. */
1647 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1648 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1650 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1651 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1653 swap_to_top (insn, regstack, *src1, *src2);
1655 replace_reg (src1, FIRST_STACK_REG);
1656 replace_reg (src2, FIRST_STACK_REG + 1);
1659 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1661 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1663 /* Pop both input operands from the stack. */
1664 CLEAR_HARD_REG_BIT (regstack->reg_set,
1665 regstack->reg[regstack->top]);
1666 CLEAR_HARD_REG_BIT (regstack->reg_set,
1667 regstack->reg[regstack->top - 1]);
1670 /* Push the result back onto the stack. */
1671 regstack->reg[++regstack->top] = REGNO (*dest);
1672 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1673 replace_reg (dest, FIRST_STACK_REG);
1676 case UNSPEC_FSCALE_FRACT:
1677 case UNSPEC_FPREM_F:
1678 case UNSPEC_FPREM1_F:
1679 /* These insns operate on the top two stack slots.
1680 first part of double input, double output insn. */
1682 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1683 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1685 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1686 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1688 /* Inputs should never die, they are
1689 replaced with outputs. */
1690 gcc_assert (!src1_note);
1691 gcc_assert (!src2_note);
1693 swap_to_top (insn, regstack, *src1, *src2);
1695 /* Push the result back onto stack. Empty stack slot
1696 will be filled in second part of insn. */
1697 if (STACK_REG_P (*dest)) {
1698 regstack->reg[regstack->top] = REGNO (*dest);
1699 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1700 replace_reg (dest, FIRST_STACK_REG);
1703 replace_reg (src1, FIRST_STACK_REG);
1704 replace_reg (src2, FIRST_STACK_REG + 1);
1707 case UNSPEC_FSCALE_EXP:
1708 case UNSPEC_FPREM_U:
1709 case UNSPEC_FPREM1_U:
1710 /* These insns operate on the top two stack slots./
1711 second part of double input, double output insn. */
1713 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1714 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1716 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1717 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1719 /* Inputs should never die, they are
1720 replaced with outputs. */
1721 gcc_assert (!src1_note);
1722 gcc_assert (!src2_note);
1724 swap_to_top (insn, regstack, *src1, *src2);
1726 /* Push the result back onto stack. Fill empty slot from
1727 first part of insn and fix top of stack pointer. */
1728 if (STACK_REG_P (*dest)) {
1729 regstack->reg[regstack->top - 1] = REGNO (*dest);
1730 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1731 replace_reg (dest, FIRST_STACK_REG + 1);
1734 replace_reg (src1, FIRST_STACK_REG);
1735 replace_reg (src2, FIRST_STACK_REG + 1);
1738 case UNSPEC_SINCOS_COS:
1739 case UNSPEC_TAN_ONE:
1740 case UNSPEC_XTRACT_FRACT:
1741 /* These insns operate on the top two stack slots,
1742 first part of one input, double output insn. */
1744 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1746 emit_swap_insn (insn, regstack, *src1);
1748 /* Input should never die, it is
1749 replaced with output. */
1750 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1751 gcc_assert (!src1_note);
1753 /* Push the result back onto stack. Empty stack slot
1754 will be filled in second part of insn. */
1755 if (STACK_REG_P (*dest)) {
1756 regstack->reg[regstack->top + 1] = REGNO (*dest);
1757 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1758 replace_reg (dest, FIRST_STACK_REG);
1761 replace_reg (src1, FIRST_STACK_REG);
1764 case UNSPEC_SINCOS_SIN:
1765 case UNSPEC_TAN_TAN:
1766 case UNSPEC_XTRACT_EXP:
1767 /* These insns operate on the top two stack slots,
1768 second part of one input, double output insn. */
1770 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1772 emit_swap_insn (insn, regstack, *src1);
1774 /* Input should never die, it is
1775 replaced with output. */
1776 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1777 gcc_assert (!src1_note);
1779 /* Push the result back onto stack. Fill empty slot from
1780 first part of insn and fix top of stack pointer. */
1781 if (STACK_REG_P (*dest)) {
1782 regstack->reg[regstack->top] = REGNO (*dest);
1783 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1784 replace_reg (dest, FIRST_STACK_REG + 1);
1789 replace_reg (src1, FIRST_STACK_REG);
1793 /* (unspec [(unspec [(compare)] UNSPEC_FNSTSW)] UNSPEC_SAHF)
1794 The combination matches the PPRO fcomi instruction. */
1796 pat_src = XVECEXP (pat_src, 0, 0);
1797 gcc_assert (GET_CODE (pat_src) == UNSPEC);
1798 gcc_assert (XINT (pat_src, 1) == UNSPEC_FNSTSW);
1802 /* Combined fcomp+fnstsw generated for doing well with
1803 CSE. When optimizing this would have been broken
1806 pat_src = XVECEXP (pat_src, 0, 0);
1807 gcc_assert (GET_CODE (pat_src) == COMPARE);
1809 compare_for_stack_reg (insn, regstack, pat_src);
1818 /* This insn requires the top of stack to be the destination. */
1820 src1 = get_true_reg (&XEXP (pat_src, 1));
1821 src2 = get_true_reg (&XEXP (pat_src, 2));
1823 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1824 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1826 /* If the comparison operator is an FP comparison operator,
1827 it is handled correctly by compare_for_stack_reg () who
1828 will move the destination to the top of stack. But if the
1829 comparison operator is not an FP comparison operator, we
1830 have to handle it here. */
1831 if (get_hard_regnum (regstack, *dest) >= FIRST_STACK_REG
1832 && REGNO (*dest) != regstack->reg[regstack->top])
1834 /* In case one of operands is the top of stack and the operands
1835 dies, it is safe to make it the destination operand by
1836 reversing the direction of cmove and avoid fxch. */
1837 if ((REGNO (*src1) == regstack->reg[regstack->top]
1839 || (REGNO (*src2) == regstack->reg[regstack->top]
1842 int idx1 = (get_hard_regnum (regstack, *src1)
1844 int idx2 = (get_hard_regnum (regstack, *src2)
1847 /* Make reg-stack believe that the operands are already
1848 swapped on the stack */
1849 regstack->reg[regstack->top - idx1] = REGNO (*src2);
1850 regstack->reg[regstack->top - idx2] = REGNO (*src1);
1852 /* Reverse condition to compensate the operand swap.
1853 i386 do have comparison always reversible. */
1854 PUT_CODE (XEXP (pat_src, 0),
1855 reversed_comparison_code (XEXP (pat_src, 0), insn));
1858 emit_swap_insn (insn, regstack, *dest);
1866 src_note[1] = src1_note;
1867 src_note[2] = src2_note;
1869 if (STACK_REG_P (*src1))
1870 replace_reg (src1, get_hard_regnum (regstack, *src1));
1871 if (STACK_REG_P (*src2))
1872 replace_reg (src2, get_hard_regnum (regstack, *src2));
1874 for (i = 1; i <= 2; i++)
1877 int regno = REGNO (XEXP (src_note[i], 0));
1879 /* If the register that dies is not at the top of
1880 stack, then move the top of stack to the dead reg.
1881 Top of stack should never die, as it is the
1883 gcc_assert (regno != regstack->reg[regstack->top]);
1884 remove_regno_note (insn, REG_DEAD, regno);
1885 emit_pop_insn (insn, regstack, XEXP (src_note[i], 0),
1890 /* Make dest the top of stack. Add dest to regstack if
1892 if (get_hard_regnum (regstack, *dest) < FIRST_STACK_REG)
1893 regstack->reg[++regstack->top] = REGNO (*dest);
1894 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1895 replace_reg (dest, FIRST_STACK_REG);
1908 return control_flow_insn_deleted;
1911 /* Substitute hard regnums for any stack regs in INSN, which has
1912 N_INPUTS inputs and N_OUTPUTS outputs. REGSTACK is the stack info
1913 before the insn, and is updated with changes made here.
1915 There are several requirements and assumptions about the use of
1916 stack-like regs in asm statements. These rules are enforced by
1917 record_asm_stack_regs; see comments there for details. Any
1918 asm_operands left in the RTL at this point may be assume to meet the
1919 requirements, since record_asm_stack_regs removes any problem asm. */
1922 subst_asm_stack_regs (rtx insn, stack regstack)
1924 rtx body = PATTERN (insn);
1927 rtx *note_reg; /* Array of note contents */
1928 rtx **note_loc; /* Address of REG field of each note */
1929 enum reg_note *note_kind; /* The type of each note */
1931 rtx *clobber_reg = 0;
1932 rtx **clobber_loc = 0;
1934 struct stack_def temp_stack;
1939 int n_inputs, n_outputs;
1941 if (! check_asm_stack_operands (insn))
1944 /* Find out what the constraints required. If no constraint
1945 alternative matches, that is a compiler bug: we should have caught
1946 such an insn in check_asm_stack_operands. */
1947 extract_insn (insn);
1948 constrain_operands (1);
1949 alt = which_alternative;
1951 preprocess_constraints ();
1953 n_inputs = get_asm_operand_n_inputs (body);
1954 n_outputs = recog_data.n_operands - n_inputs;
1956 gcc_assert (alt >= 0);
1958 /* Strip SUBREGs here to make the following code simpler. */
1959 for (i = 0; i < recog_data.n_operands; i++)
1960 if (GET_CODE (recog_data.operand[i]) == SUBREG
1961 && REG_P (SUBREG_REG (recog_data.operand[i])))
1963 recog_data.operand_loc[i] = & SUBREG_REG (recog_data.operand[i]);
1964 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
1967 /* Set up NOTE_REG, NOTE_LOC and NOTE_KIND. */
1969 for (i = 0, note = REG_NOTES (insn); note; note = XEXP (note, 1))
1972 note_reg = alloca (i * sizeof (rtx));
1973 note_loc = alloca (i * sizeof (rtx *));
1974 note_kind = alloca (i * sizeof (enum reg_note));
1977 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
1979 rtx reg = XEXP (note, 0);
1980 rtx *loc = & XEXP (note, 0);
1982 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
1984 loc = & SUBREG_REG (reg);
1985 reg = SUBREG_REG (reg);
1988 if (STACK_REG_P (reg)
1989 && (REG_NOTE_KIND (note) == REG_DEAD
1990 || REG_NOTE_KIND (note) == REG_UNUSED))
1992 note_reg[n_notes] = reg;
1993 note_loc[n_notes] = loc;
1994 note_kind[n_notes] = REG_NOTE_KIND (note);
1999 /* Set up CLOBBER_REG and CLOBBER_LOC. */
2003 if (GET_CODE (body) == PARALLEL)
2005 clobber_reg = alloca (XVECLEN (body, 0) * sizeof (rtx));
2006 clobber_loc = alloca (XVECLEN (body, 0) * sizeof (rtx *));
2008 for (i = 0; i < XVECLEN (body, 0); i++)
2009 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
2011 rtx clobber = XVECEXP (body, 0, i);
2012 rtx reg = XEXP (clobber, 0);
2013 rtx *loc = & XEXP (clobber, 0);
2015 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
2017 loc = & SUBREG_REG (reg);
2018 reg = SUBREG_REG (reg);
2021 if (STACK_REG_P (reg))
2023 clobber_reg[n_clobbers] = reg;
2024 clobber_loc[n_clobbers] = loc;
2030 temp_stack = *regstack;
2032 /* Put the input regs into the desired place in TEMP_STACK. */
2034 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2035 if (STACK_REG_P (recog_data.operand[i])
2036 && reg_class_subset_p (recog_op_alt[i][alt].cl,
2038 && recog_op_alt[i][alt].cl != FLOAT_REGS)
2040 /* If an operand needs to be in a particular reg in
2041 FLOAT_REGS, the constraint was either 't' or 'u'. Since
2042 these constraints are for single register classes, and
2043 reload guaranteed that operand[i] is already in that class,
2044 we can just use REGNO (recog_data.operand[i]) to know which
2045 actual reg this operand needs to be in. */
2047 int regno = get_hard_regnum (&temp_stack, recog_data.operand[i]);
2049 gcc_assert (regno >= 0);
2051 if ((unsigned int) regno != REGNO (recog_data.operand[i]))
2053 /* recog_data.operand[i] is not in the right place. Find
2054 it and swap it with whatever is already in I's place.
2055 K is where recog_data.operand[i] is now. J is where it
2059 k = temp_stack.top - (regno - FIRST_STACK_REG);
2061 - (REGNO (recog_data.operand[i]) - FIRST_STACK_REG));
2063 temp = temp_stack.reg[k];
2064 temp_stack.reg[k] = temp_stack.reg[j];
2065 temp_stack.reg[j] = temp;
2069 /* Emit insns before INSN to make sure the reg-stack is in the right
2072 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
2074 /* Make the needed input register substitutions. Do death notes and
2075 clobbers too, because these are for inputs, not outputs. */
2077 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2078 if (STACK_REG_P (recog_data.operand[i]))
2080 int regnum = get_hard_regnum (regstack, recog_data.operand[i]);
2082 gcc_assert (regnum >= 0);
2084 replace_reg (recog_data.operand_loc[i], regnum);
2087 for (i = 0; i < n_notes; i++)
2088 if (note_kind[i] == REG_DEAD)
2090 int regnum = get_hard_regnum (regstack, note_reg[i]);
2092 gcc_assert (regnum >= 0);
2094 replace_reg (note_loc[i], regnum);
2097 for (i = 0; i < n_clobbers; i++)
2099 /* It's OK for a CLOBBER to reference a reg that is not live.
2100 Don't try to replace it in that case. */
2101 int regnum = get_hard_regnum (regstack, clobber_reg[i]);
2105 /* Sigh - clobbers always have QImode. But replace_reg knows
2106 that these regs can't be MODE_INT and will assert. Just put
2107 the right reg there without calling replace_reg. */
2109 *clobber_loc[i] = FP_MODE_REG (regnum, DFmode);
2113 /* Now remove from REGSTACK any inputs that the asm implicitly popped. */
2115 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2116 if (STACK_REG_P (recog_data.operand[i]))
2118 /* An input reg is implicitly popped if it is tied to an
2119 output, or if there is a CLOBBER for it. */
2122 for (j = 0; j < n_clobbers; j++)
2123 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
2126 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
2128 /* recog_data.operand[i] might not be at the top of stack.
2129 But that's OK, because all we need to do is pop the
2130 right number of regs off of the top of the reg-stack.
2131 record_asm_stack_regs guaranteed that all implicitly
2132 popped regs were grouped at the top of the reg-stack. */
2134 CLEAR_HARD_REG_BIT (regstack->reg_set,
2135 regstack->reg[regstack->top]);
2140 /* Now add to REGSTACK any outputs that the asm implicitly pushed.
2141 Note that there isn't any need to substitute register numbers.
2142 ??? Explain why this is true. */
2144 for (i = LAST_STACK_REG; i >= FIRST_STACK_REG; i--)
2146 /* See if there is an output for this hard reg. */
2149 for (j = 0; j < n_outputs; j++)
2150 if (STACK_REG_P (recog_data.operand[j])
2151 && REGNO (recog_data.operand[j]) == (unsigned) i)
2153 regstack->reg[++regstack->top] = i;
2154 SET_HARD_REG_BIT (regstack->reg_set, i);
2159 /* Now emit a pop insn for any REG_UNUSED output, or any REG_DEAD
2160 input that the asm didn't implicitly pop. If the asm didn't
2161 implicitly pop an input reg, that reg will still be live.
2163 Note that we can't use find_regno_note here: the register numbers
2164 in the death notes have already been substituted. */
2166 for (i = 0; i < n_outputs; i++)
2167 if (STACK_REG_P (recog_data.operand[i]))
2171 for (j = 0; j < n_notes; j++)
2172 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2173 && note_kind[j] == REG_UNUSED)
2175 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2181 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2182 if (STACK_REG_P (recog_data.operand[i]))
2186 for (j = 0; j < n_notes; j++)
2187 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2188 && note_kind[j] == REG_DEAD
2189 && TEST_HARD_REG_BIT (regstack->reg_set,
2190 REGNO (recog_data.operand[i])))
2192 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2199 /* Substitute stack hard reg numbers for stack virtual registers in
2200 INSN. Non-stack register numbers are not changed. REGSTACK is the
2201 current stack content. Insns may be emitted as needed to arrange the
2202 stack for the 387 based on the contents of the insn. Return whether
2203 a control flow insn was deleted in the process. */
2206 subst_stack_regs (rtx insn, stack regstack)
2208 rtx *note_link, note;
2209 bool control_flow_insn_deleted = false;
2214 int top = regstack->top;
2216 /* If there are any floating point parameters to be passed in
2217 registers for this call, make sure they are in the right
2222 straighten_stack (insn, regstack);
2224 /* Now mark the arguments as dead after the call. */
2226 while (regstack->top >= 0)
2228 CLEAR_HARD_REG_BIT (regstack->reg_set, FIRST_STACK_REG + regstack->top);
2234 /* Do the actual substitution if any stack regs are mentioned.
2235 Since we only record whether entire insn mentions stack regs, and
2236 subst_stack_regs_pat only works for patterns that contain stack regs,
2237 we must check each pattern in a parallel here. A call_value_pop could
2240 if (stack_regs_mentioned (insn))
2242 int n_operands = asm_noperands (PATTERN (insn));
2243 if (n_operands >= 0)
2245 /* This insn is an `asm' with operands. Decode the operands,
2246 decide how many are inputs, and do register substitution.
2247 Any REG_UNUSED notes will be handled by subst_asm_stack_regs. */
2249 subst_asm_stack_regs (insn, regstack);
2250 return control_flow_insn_deleted;
2253 if (GET_CODE (PATTERN (insn)) == PARALLEL)
2254 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
2256 if (stack_regs_mentioned_p (XVECEXP (PATTERN (insn), 0, i)))
2258 if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == CLOBBER)
2259 XVECEXP (PATTERN (insn), 0, i)
2260 = shallow_copy_rtx (XVECEXP (PATTERN (insn), 0, i));
2261 control_flow_insn_deleted
2262 |= subst_stack_regs_pat (insn, regstack,
2263 XVECEXP (PATTERN (insn), 0, i));
2267 control_flow_insn_deleted
2268 |= subst_stack_regs_pat (insn, regstack, PATTERN (insn));
2271 /* subst_stack_regs_pat may have deleted a no-op insn. If so, any
2272 REG_UNUSED will already have been dealt with, so just return. */
2274 if (NOTE_P (insn) || INSN_DELETED_P (insn))
2275 return control_flow_insn_deleted;
2277 /* If there is a REG_UNUSED note on a stack register on this insn,
2278 the indicated reg must be popped. The REG_UNUSED note is removed,
2279 since the form of the newly emitted pop insn references the reg,
2280 making it no longer `unset'. */
2282 note_link = ®_NOTES (insn);
2283 for (note = *note_link; note; note = XEXP (note, 1))
2284 if (REG_NOTE_KIND (note) == REG_UNUSED && STACK_REG_P (XEXP (note, 0)))
2286 *note_link = XEXP (note, 1);
2287 insn = emit_pop_insn (insn, regstack, XEXP (note, 0), EMIT_AFTER);
2290 note_link = &XEXP (note, 1);
2292 return control_flow_insn_deleted;
2295 /* Change the organization of the stack so that it fits a new basic
2296 block. Some registers might have to be popped, but there can never be
2297 a register live in the new block that is not now live.
2299 Insert any needed insns before or after INSN, as indicated by
2300 WHERE. OLD is the original stack layout, and NEW is the desired
2301 form. OLD is updated to reflect the code emitted, i.e., it will be
2302 the same as NEW upon return.
2304 This function will not preserve block_end[]. But that information
2305 is no longer needed once this has executed. */
2308 change_stack (rtx insn, stack old, stack new, enum emit_where where)
2313 /* Stack adjustments for the first insn in a block update the
2314 current_block's stack_in instead of inserting insns directly.
2315 compensate_edges will add the necessary code later. */
2318 && where == EMIT_BEFORE)
2320 BLOCK_INFO (current_block)->stack_in = *new;
2321 starting_stack_p = false;
2326 /* We will be inserting new insns "backwards". If we are to insert
2327 after INSN, find the next insn, and insert before it. */
2329 if (where == EMIT_AFTER)
2331 if (current_block && BB_END (current_block) == insn)
2333 insn = NEXT_INSN (insn);
2336 /* Pop any registers that are not needed in the new block. */
2338 /* If the destination block's stack already has a specified layout
2339 and contains two or more registers, use a more intelligent algorithm
2340 to pop registers that minimizes the number number of fxchs below. */
2343 bool slots[REG_STACK_SIZE];
2344 int pops[REG_STACK_SIZE];
2345 int next, dest, topsrc;
2347 /* First pass to determine the free slots. */
2348 for (reg = 0; reg <= new->top; reg++)
2349 slots[reg] = TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]);
2351 /* Second pass to allocate preferred slots. */
2353 for (reg = old->top; reg > new->top; reg--)
2354 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2357 for (next = 0; next <= new->top; next++)
2358 if (!slots[next] && new->reg[next] == old->reg[reg])
2360 /* If this is a preference for the new top of stack, record
2361 the fact by remembering it's old->reg in topsrc. */
2362 if (next == new->top)
2373 /* Intentionally, avoid placing the top of stack in it's correct
2374 location, if we still need to permute the stack below and we
2375 can usefully place it somewhere else. This is the case if any
2376 slot is still unallocated, in which case we should place the
2377 top of stack there. */
2379 for (reg = 0; reg < new->top; reg++)
2383 slots[new->top] = false;
2388 /* Third pass allocates remaining slots and emits pop insns. */
2390 for (reg = old->top; reg > new->top; reg--)
2395 /* Find next free slot. */
2400 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[dest], DFmode),
2406 /* The following loop attempts to maximize the number of times we
2407 pop the top of the stack, as this permits the use of the faster
2408 ffreep instruction on platforms that support it. */
2412 for (reg = 0; reg <= old->top; reg++)
2413 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2417 while (old->top >= live)
2418 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[old->top]))
2420 while (TEST_HARD_REG_BIT (new->reg_set, old->reg[next]))
2422 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[next], DFmode),
2426 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[old->top], DFmode),
2432 /* If the new block has never been processed, then it can inherit
2433 the old stack order. */
2435 new->top = old->top;
2436 memcpy (new->reg, old->reg, sizeof (new->reg));
2440 /* This block has been entered before, and we must match the
2441 previously selected stack order. */
2443 /* By now, the only difference should be the order of the stack,
2444 not their depth or liveliness. */
2446 GO_IF_HARD_REG_EQUAL (old->reg_set, new->reg_set, win);
2449 gcc_assert (old->top == new->top);
2451 /* If the stack is not empty (new->top != -1), loop here emitting
2452 swaps until the stack is correct.
2454 The worst case number of swaps emitted is N + 2, where N is the
2455 depth of the stack. In some cases, the reg at the top of
2456 stack may be correct, but swapped anyway in order to fix
2457 other regs. But since we never swap any other reg away from
2458 its correct slot, this algorithm will converge. */
2463 /* Swap the reg at top of stack into the position it is
2464 supposed to be in, until the correct top of stack appears. */
2466 while (old->reg[old->top] != new->reg[new->top])
2468 for (reg = new->top; reg >= 0; reg--)
2469 if (new->reg[reg] == old->reg[old->top])
2472 gcc_assert (reg != -1);
2474 emit_swap_insn (insn, old,
2475 FP_MODE_REG (old->reg[reg], DFmode));
2478 /* See if any regs remain incorrect. If so, bring an
2479 incorrect reg to the top of stack, and let the while loop
2482 for (reg = new->top; reg >= 0; reg--)
2483 if (new->reg[reg] != old->reg[reg])
2485 emit_swap_insn (insn, old,
2486 FP_MODE_REG (old->reg[reg], DFmode));
2491 /* At this point there must be no differences. */
2493 for (reg = old->top; reg >= 0; reg--)
2494 gcc_assert (old->reg[reg] == new->reg[reg]);
2498 BB_END (current_block) = PREV_INSN (insn);
2501 /* Print stack configuration. */
2504 print_stack (FILE *file, stack s)
2510 fprintf (file, "uninitialized\n");
2511 else if (s->top == -1)
2512 fprintf (file, "empty\n");
2517 for (i = 0; i <= s->top; ++i)
2518 fprintf (file, "%d ", s->reg[i]);
2519 fputs ("]\n", file);
2523 /* This function was doing life analysis. We now let the regular live
2524 code do it's job, so we only need to check some extra invariants
2525 that reg-stack expects. Primary among these being that all registers
2526 are initialized before use.
2528 The function returns true when code was emitted to CFG edges and
2529 commit_edge_insertions needs to be called. */
2532 convert_regs_entry (void)
2538 /* Load something into each stack register live at function entry.
2539 Such live registers can be caused by uninitialized variables or
2540 functions not returning values on all paths. In order to keep
2541 the push/pop code happy, and to not scrog the register stack, we
2542 must put something in these registers. Use a QNaN.
2544 Note that we are inserting converted code here. This code is
2545 never seen by the convert_regs pass. */
2547 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2549 basic_block block = e->dest;
2550 block_info bi = BLOCK_INFO (block);
2553 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2554 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2558 bi->stack_in.reg[++top] = reg;
2560 init = gen_rtx_SET (VOIDmode,
2561 FP_MODE_REG (FIRST_STACK_REG, SFmode),
2563 insert_insn_on_edge (init, e);
2567 bi->stack_in.top = top;
2573 /* Construct the desired stack for function exit. This will either
2574 be `empty', or the function return value at top-of-stack. */
2577 convert_regs_exit (void)
2579 int value_reg_low, value_reg_high;
2583 retvalue = stack_result (current_function_decl);
2584 value_reg_low = value_reg_high = -1;
2587 value_reg_low = REGNO (retvalue);
2588 value_reg_high = value_reg_low
2589 + hard_regno_nregs[value_reg_low][GET_MODE (retvalue)] - 1;
2592 output_stack = &BLOCK_INFO (EXIT_BLOCK_PTR)->stack_in;
2593 if (value_reg_low == -1)
2594 output_stack->top = -1;
2599 output_stack->top = value_reg_high - value_reg_low;
2600 for (reg = value_reg_low; reg <= value_reg_high; ++reg)
2602 output_stack->reg[value_reg_high - reg] = reg;
2603 SET_HARD_REG_BIT (output_stack->reg_set, reg);
2608 /* Copy the stack info from the end of edge E's source block to the
2609 start of E's destination block. */
2612 propagate_stack (edge e)
2614 stack src_stack = &BLOCK_INFO (e->src)->stack_out;
2615 stack dest_stack = &BLOCK_INFO (e->dest)->stack_in;
2618 /* Preserve the order of the original stack, but check whether
2619 any pops are needed. */
2620 dest_stack->top = -1;
2621 for (reg = 0; reg <= src_stack->top; ++reg)
2622 if (TEST_HARD_REG_BIT (dest_stack->reg_set, src_stack->reg[reg]))
2623 dest_stack->reg[++dest_stack->top] = src_stack->reg[reg];
2627 /* Adjust the stack of edge E's source block on exit to match the stack
2628 of it's target block upon input. The stack layouts of both blocks
2629 should have been defined by now. */
2632 compensate_edge (edge e, FILE *file)
2634 basic_block source = e->src, target = e->dest;
2635 stack target_stack = &BLOCK_INFO (target)->stack_in;
2636 stack source_stack = &BLOCK_INFO (source)->stack_out;
2637 struct stack_def regstack;
2641 fprintf (file, "Edge %d->%d: ", source->index, target->index);
2643 gcc_assert (target_stack->top != -2);
2645 /* Check whether stacks are identical. */
2646 if (target_stack->top == source_stack->top)
2648 for (reg = target_stack->top; reg >= 0; --reg)
2649 if (target_stack->reg[reg] != source_stack->reg[reg])
2655 fprintf (file, "no changes needed\n");
2662 fprintf (file, "correcting stack to ");
2663 print_stack (file, target_stack);
2666 /* Abnormal calls may appear to have values live in st(0), but the
2667 abnormal return path will not have actually loaded the values. */
2668 if (e->flags & EDGE_ABNORMAL_CALL)
2670 /* Assert that the lifetimes are as we expect -- one value
2671 live at st(0) on the end of the source block, and no
2672 values live at the beginning of the destination block.
2673 For complex return values, we may have st(1) live as well. */
2674 gcc_assert (source_stack->top == 0 || source_stack->top == 1);
2675 gcc_assert (target_stack->top == -1);
2679 /* Handle non-call EH edges specially. The normal return path have
2680 values in registers. These will be popped en masse by the unwind
2682 if (e->flags & EDGE_EH)
2684 gcc_assert (target_stack->top == -1);
2688 /* We don't support abnormal edges. Global takes care to
2689 avoid any live register across them, so we should never
2690 have to insert instructions on such edges. */
2691 gcc_assert (! (e->flags & EDGE_ABNORMAL));
2693 /* Make a copy of source_stack as change_stack is destructive. */
2694 regstack = *source_stack;
2696 /* It is better to output directly to the end of the block
2697 instead of to the edge, because emit_swap can do minimal
2698 insn scheduling. We can do this when there is only one
2699 edge out, and it is not abnormal. */
2700 if (EDGE_COUNT (source->succs) == 1)
2702 current_block = source;
2703 change_stack (BB_END (source), ®stack, target_stack,
2704 (JUMP_P (BB_END (source)) ? EMIT_BEFORE : EMIT_AFTER));
2710 current_block = NULL;
2713 /* ??? change_stack needs some point to emit insns after. */
2714 after = emit_note (NOTE_INSN_DELETED);
2716 change_stack (after, ®stack, target_stack, EMIT_BEFORE);
2721 insert_insn_on_edge (seq, e);
2727 /* Traverse all non-entry edges in the CFG, and emit the necessary
2728 edge compensation code to change the stack from stack_out of the
2729 source block to the stack_in of the destination block. */
2732 compensate_edges (FILE *file)
2734 bool inserted = false;
2737 starting_stack_p = false;
2740 if (bb != ENTRY_BLOCK_PTR)
2745 FOR_EACH_EDGE (e, ei, bb->succs)
2746 inserted |= compensate_edge (e, file);
2751 /* Select the better of two edges E1 and E2 to use to determine the
2752 stack layout for their shared destination basic block. This is
2753 typically the more frequently executed. The edge E1 may be NULL
2754 (in which case E2 is returned), but E2 is always non-NULL. */
2757 better_edge (edge e1, edge e2)
2762 if (EDGE_FREQUENCY (e1) > EDGE_FREQUENCY (e2))
2764 if (EDGE_FREQUENCY (e1) < EDGE_FREQUENCY (e2))
2767 if (e1->count > e2->count)
2769 if (e1->count < e2->count)
2772 /* Prefer critical edges to minimize inserting compensation code on
2775 if (EDGE_CRITICAL_P (e1) != EDGE_CRITICAL_P (e2))
2776 return EDGE_CRITICAL_P (e1) ? e1 : e2;
2778 /* Avoid non-deterministic behaviour. */
2779 return (e1->src->index < e2->src->index) ? e1 : e2;
2782 /* Convert stack register references in one block. */
2785 convert_regs_1 (FILE *file, basic_block block)
2787 struct stack_def regstack;
2788 block_info bi = BLOCK_INFO (block);
2791 bool control_flow_insn_deleted = false;
2793 any_malformed_asm = false;
2795 /* Choose an initial stack layout, if one hasn't already been chosen. */
2796 if (bi->stack_in.top == -2)
2798 edge e, beste = NULL;
2801 /* Select the best incoming edge (typically the most frequent) to
2802 use as a template for this basic block. */
2803 FOR_EACH_EDGE (e, ei, block->preds)
2804 if (BLOCK_INFO (e->src)->done)
2805 beste = better_edge (beste, e);
2808 propagate_stack (beste);
2811 /* No predecessors. Create an arbitrary input stack. */
2812 bi->stack_in.top = -1;
2813 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2814 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2815 bi->stack_in.reg[++bi->stack_in.top] = reg;
2821 fprintf (file, "\nBasic block %d\nInput stack: ", block->index);
2822 print_stack (file, &bi->stack_in);
2825 /* Process all insns in this block. Keep track of NEXT so that we
2826 don't process insns emitted while substituting in INSN. */
2827 current_block = block;
2828 next = BB_HEAD (block);
2829 regstack = bi->stack_in;
2830 starting_stack_p = true;
2835 next = NEXT_INSN (insn);
2837 /* Ensure we have not missed a block boundary. */
2839 if (insn == BB_END (block))
2842 /* Don't bother processing unless there is a stack reg
2843 mentioned or if it's a CALL_INSN. */
2844 if (stack_regs_mentioned (insn)
2849 fprintf (file, " insn %d input stack: ",
2851 print_stack (file, ®stack);
2853 control_flow_insn_deleted |= subst_stack_regs (insn, ®stack);
2854 starting_stack_p = false;
2861 fprintf (file, "Expected live registers [");
2862 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2863 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg))
2864 fprintf (file, " %d", reg);
2865 fprintf (file, " ]\nOutput stack: ");
2866 print_stack (file, ®stack);
2869 insn = BB_END (block);
2871 insn = PREV_INSN (insn);
2873 /* If the function is declared to return a value, but it returns one
2874 in only some cases, some registers might come live here. Emit
2875 necessary moves for them. */
2877 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2879 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg)
2880 && ! TEST_HARD_REG_BIT (regstack.reg_set, reg))
2885 fprintf (file, "Emitting insn initializing reg %d\n", reg);
2887 set = gen_rtx_SET (VOIDmode, FP_MODE_REG (reg, SFmode), not_a_num);
2888 insn = emit_insn_after (set, insn);
2889 control_flow_insn_deleted |= subst_stack_regs (insn, ®stack);
2893 /* Amongst the insns possibly deleted during the substitution process above,
2894 might have been the only trapping insn in the block. We purge the now
2895 possibly dead EH edges here to avoid an ICE from fixup_abnormal_edges,
2896 called at the end of convert_regs. The order in which we process the
2897 blocks ensures that we never delete an already processed edge.
2899 Note that, at this point, the CFG may have been damaged by the emission
2900 of instructions after an abnormal call, which moves the basic block end
2901 (and is the reason why we call fixup_abnormal_edges later). So we must
2902 be sure that the trapping insn has been deleted before trying to purge
2903 dead edges, otherwise we risk purging valid edges.
2905 ??? We are normally supposed not to delete trapping insns, so we pretend
2906 that the insns deleted above don't actually trap. It would have been
2907 better to detect this earlier and avoid creating the EH edge in the first
2908 place, still, but we don't have enough information at that time. */
2910 if (control_flow_insn_deleted)
2911 purge_dead_edges (block);
2913 /* Something failed if the stack lives don't match. If we had malformed
2914 asms, we zapped the instruction itself, but that didn't produce the
2915 same pattern of register kills as before. */
2916 GO_IF_HARD_REG_EQUAL (regstack.reg_set, bi->out_reg_set, win);
2917 gcc_assert (any_malformed_asm);
2919 bi->stack_out = regstack;
2923 /* Convert registers in all blocks reachable from BLOCK. */
2926 convert_regs_2 (FILE *file, basic_block block)
2928 basic_block *stack, *sp;
2930 /* We process the blocks in a top-down manner, in a way such that one block
2931 is only processed after all its predecessors. The number of predecessors
2932 of every block has already been computed. */
2934 stack = xmalloc (sizeof (*stack) * n_basic_blocks);
2946 /* Processing BLOCK is achieved by convert_regs_1, which may purge
2947 some dead EH outgoing edge after the deletion of the trapping
2948 insn inside the block. Since the number of predecessors of
2949 BLOCK's successors was computed based on the initial edge set,
2950 we check the necessity to process some of these successors
2951 before such an edge deletion may happen. However, there is
2952 a pitfall: if BLOCK is the only predecessor of a successor and
2953 the edge between them happens to be deleted, the successor
2954 becomes unreachable and should not be processed. The problem
2955 is that there is no way to preventively detect this case so we
2956 stack the successor in all cases and hand over the task of
2957 fixing up the discrepancy to convert_regs_1. */
2959 FOR_EACH_EDGE (e, ei, block->succs)
2960 if (! (e->flags & EDGE_DFS_BACK))
2962 BLOCK_INFO (e->dest)->predecessors--;
2963 if (!BLOCK_INFO (e->dest)->predecessors)
2967 convert_regs_1 (file, block);
2969 while (sp != stack);
2974 /* Traverse all basic blocks in a function, converting the register
2975 references in each insn from the "flat" register file that gcc uses,
2976 to the stack-like registers the 387 uses. */
2979 convert_regs (FILE *file)
2986 /* Initialize uninitialized registers on function entry. */
2987 inserted = convert_regs_entry ();
2989 /* Construct the desired stack for function exit. */
2990 convert_regs_exit ();
2991 BLOCK_INFO (EXIT_BLOCK_PTR)->done = 1;
2993 /* ??? Future: process inner loops first, and give them arbitrary
2994 initial stacks which emit_swap_insn can modify. This ought to
2995 prevent double fxch that often appears at the head of a loop. */
2997 /* Process all blocks reachable from all entry points. */
2998 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2999 convert_regs_2 (file, e->dest);
3001 /* ??? Process all unreachable blocks. Though there's no excuse
3002 for keeping these even when not optimizing. */
3005 block_info bi = BLOCK_INFO (b);
3008 convert_regs_2 (file, b);
3011 inserted |= compensate_edges (file);
3013 clear_aux_for_blocks ();
3015 fixup_abnormal_edges ();
3017 commit_edge_insertions ();
3023 /* Convert register usage from "flat" register file usage to a "stack
3024 register file. FILE is the dump file, if used.
3026 Construct a CFG and run life analysis. Then convert each insn one
3027 by one. Run a last cleanup_cfg pass, if optimizing, to eliminate
3028 code duplication created when the converter inserts pop insns on
3032 reg_to_stack (FILE *file)
3038 /* Clean up previous run. */
3039 stack_regs_mentioned_data = 0;
3041 /* See if there is something to do. Flow analysis is quite
3042 expensive so we might save some compilation time. */
3043 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
3044 if (regs_ever_live[i])
3046 if (i > LAST_STACK_REG)
3049 /* Ok, floating point instructions exist. If not optimizing,
3050 build the CFG and run life analysis.
3051 Also need to rebuild life when superblock scheduling is done
3052 as it don't update liveness yet. */
3054 || (flag_sched2_use_superblocks
3055 && flag_schedule_insns_after_reload))
3057 count_or_remove_death_notes (NULL, 1);
3058 life_analysis (file, PROP_DEATH_NOTES);
3060 mark_dfs_back_edges ();
3062 /* Set up block info for each basic block. */
3063 alloc_aux_for_blocks (sizeof (struct block_info_def));
3066 block_info bi = BLOCK_INFO (bb);
3071 FOR_EACH_EDGE (e, ei, bb->preds)
3072 if (!(e->flags & EDGE_DFS_BACK)
3073 && e->src != ENTRY_BLOCK_PTR)
3076 /* Set current register status at last instruction `uninitialized'. */
3077 bi->stack_in.top = -2;
3079 /* Copy live_at_end and live_at_start into temporaries. */
3080 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; reg++)
3082 if (REGNO_REG_SET_P (bb->il.rtl->global_live_at_end, reg))
3083 SET_HARD_REG_BIT (bi->out_reg_set, reg);
3084 if (REGNO_REG_SET_P (bb->il.rtl->global_live_at_start, reg))
3085 SET_HARD_REG_BIT (bi->stack_in.reg_set, reg);
3089 /* Create the replacement registers up front. */
3090 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
3092 enum machine_mode mode;
3093 for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT);
3095 mode = GET_MODE_WIDER_MODE (mode))
3096 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
3097 for (mode = GET_CLASS_NARROWEST_MODE (MODE_COMPLEX_FLOAT);
3099 mode = GET_MODE_WIDER_MODE (mode))
3100 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
3103 ix86_flags_rtx = gen_rtx_REG (CCmode, FLAGS_REG);
3105 /* A QNaN for initializing uninitialized variables.
3107 ??? We can't load from constant memory in PIC mode, because
3108 we're inserting these instructions before the prologue and
3109 the PIC register hasn't been set up. In that case, fall back
3110 on zero, which we can get from `ldz'. */
3113 not_a_num = CONST0_RTX (SFmode);
3116 not_a_num = gen_lowpart (SFmode, GEN_INT (0x7fc00000));
3117 not_a_num = force_const_mem (SFmode, not_a_num);
3120 /* Allocate a cache for stack_regs_mentioned. */
3121 max_uid = get_max_uid ();
3122 VARRAY_CHAR_INIT (stack_regs_mentioned_data, max_uid + 1,
3123 "stack_regs_mentioned cache");
3125 convert_regs (file);
3127 free_aux_for_blocks ();
3130 #endif /* STACK_REGS */
3133 gate_handle_stack_regs (void)
3142 /* Convert register usage from flat register file usage to a stack
3145 rest_of_handle_stack_regs (void)
3148 if (reg_to_stack (dump_file) && optimize)
3150 if (cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_POST_REGSTACK
3151 | (flag_crossjumping ? CLEANUP_CROSSJUMP : 0))
3152 && (flag_reorder_blocks || flag_reorder_blocks_and_partition))
3154 reorder_basic_blocks (0);
3155 cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_POST_REGSTACK);
3161 struct tree_opt_pass pass_stack_regs =
3164 gate_handle_stack_regs, /* gate */
3165 rest_of_handle_stack_regs, /* execute */
3168 0, /* static_pass_number */
3169 TV_REG_STACK, /* tv_id */
3170 0, /* properties_required */
3171 0, /* properties_provided */
3172 0, /* properties_destroyed */
3173 0, /* todo_flags_start */
3175 TODO_ggc_collect, /* todo_flags_finish */
3179 #include "gt-reg-stack.h"