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 void print_stack (FILE *, stack);
263 static rtx next_flags_user (rtx);
265 /* Return nonzero if any stack register is mentioned somewhere within PAT. */
268 stack_regs_mentioned_p (rtx pat)
273 if (STACK_REG_P (pat))
276 fmt = GET_RTX_FORMAT (GET_CODE (pat));
277 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
283 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
284 if (stack_regs_mentioned_p (XVECEXP (pat, i, j)))
287 else if (fmt[i] == 'e' && stack_regs_mentioned_p (XEXP (pat, i)))
294 /* Return nonzero if INSN mentions stacked registers, else return zero. */
297 stack_regs_mentioned (rtx insn)
299 unsigned int uid, max;
302 if (! INSN_P (insn) || !stack_regs_mentioned_data)
305 uid = INSN_UID (insn);
306 max = VARRAY_SIZE (stack_regs_mentioned_data);
309 /* Allocate some extra size to avoid too many reallocs, but
310 do not grow too quickly. */
311 max = uid + uid / 20;
312 VARRAY_GROW (stack_regs_mentioned_data, max);
315 test = VARRAY_CHAR (stack_regs_mentioned_data, uid);
318 /* This insn has yet to be examined. Do so now. */
319 test = stack_regs_mentioned_p (PATTERN (insn)) ? 1 : 2;
320 VARRAY_CHAR (stack_regs_mentioned_data, uid) = test;
326 static rtx ix86_flags_rtx;
329 next_flags_user (rtx insn)
331 /* Search forward looking for the first use of this value.
332 Stop at block boundaries. */
334 while (insn != BB_END (current_block))
336 insn = NEXT_INSN (insn);
338 if (INSN_P (insn) && reg_mentioned_p (ix86_flags_rtx, PATTERN (insn)))
347 /* Reorganize the stack into ascending numbers,
351 straighten_stack (rtx insn, stack regstack)
353 struct stack_def temp_stack;
356 /* If there is only a single register on the stack, then the stack is
357 already in increasing order and no reorganization is needed.
359 Similarly if the stack is empty. */
360 if (regstack->top <= 0)
363 COPY_HARD_REG_SET (temp_stack.reg_set, regstack->reg_set);
365 for (top = temp_stack.top = regstack->top; top >= 0; top--)
366 temp_stack.reg[top] = FIRST_STACK_REG + temp_stack.top - top;
368 change_stack (insn, regstack, &temp_stack, EMIT_AFTER);
371 /* Pop a register from the stack. */
374 pop_stack (stack regstack, int regno)
376 int top = regstack->top;
378 CLEAR_HARD_REG_BIT (regstack->reg_set, regno);
380 /* If regno was not at the top of stack then adjust stack. */
381 if (regstack->reg [top] != regno)
384 for (i = regstack->top; i >= 0; i--)
385 if (regstack->reg [i] == regno)
388 for (j = i; j < top; j++)
389 regstack->reg [j] = regstack->reg [j + 1];
395 /* Return a pointer to the REG expression within PAT. If PAT is not a
396 REG, possible enclosed by a conversion rtx, return the inner part of
397 PAT that stopped the search. */
400 get_true_reg (rtx *pat)
403 switch (GET_CODE (*pat))
406 /* Eliminate FP subregister accesses in favor of the
407 actual FP register in use. */
410 if (FP_REG_P (subreg = SUBREG_REG (*pat)))
412 int regno_off = subreg_regno_offset (REGNO (subreg),
416 *pat = FP_MODE_REG (REGNO (subreg) + regno_off,
425 pat = & XEXP (*pat, 0);
429 if (!flag_unsafe_math_optimizations)
431 pat = & XEXP (*pat, 0);
436 /* Set if we find any malformed asms in a block. */
437 static bool any_malformed_asm;
439 /* There are many rules that an asm statement for stack-like regs must
440 follow. Those rules are explained at the top of this file: the rule
441 numbers below refer to that explanation. */
444 check_asm_stack_operands (rtx insn)
448 int malformed_asm = 0;
449 rtx body = PATTERN (insn);
451 char reg_used_as_output[FIRST_PSEUDO_REGISTER];
452 char implicitly_dies[FIRST_PSEUDO_REGISTER];
455 rtx *clobber_reg = 0;
456 int n_inputs, n_outputs;
458 /* Find out what the constraints require. If no constraint
459 alternative matches, this asm is malformed. */
461 constrain_operands (1);
462 alt = which_alternative;
464 preprocess_constraints ();
466 n_inputs = get_asm_operand_n_inputs (body);
467 n_outputs = recog_data.n_operands - n_inputs;
472 /* Avoid further trouble with this insn. */
473 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
477 /* Strip SUBREGs here to make the following code simpler. */
478 for (i = 0; i < recog_data.n_operands; i++)
479 if (GET_CODE (recog_data.operand[i]) == SUBREG
480 && REG_P (SUBREG_REG (recog_data.operand[i])))
481 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
483 /* Set up CLOBBER_REG. */
487 if (GET_CODE (body) == PARALLEL)
489 clobber_reg = alloca (XVECLEN (body, 0) * sizeof (rtx));
491 for (i = 0; i < XVECLEN (body, 0); i++)
492 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
494 rtx clobber = XVECEXP (body, 0, i);
495 rtx reg = XEXP (clobber, 0);
497 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
498 reg = SUBREG_REG (reg);
500 if (STACK_REG_P (reg))
502 clobber_reg[n_clobbers] = reg;
508 /* Enforce rule #4: Output operands must specifically indicate which
509 reg an output appears in after an asm. "=f" is not allowed: the
510 operand constraints must select a class with a single reg.
512 Also enforce rule #5: Output operands must start at the top of
513 the reg-stack: output operands may not "skip" a reg. */
515 memset (reg_used_as_output, 0, sizeof (reg_used_as_output));
516 for (i = 0; i < n_outputs; i++)
517 if (STACK_REG_P (recog_data.operand[i]))
519 if (reg_class_size[(int) recog_op_alt[i][alt].cl] != 1)
521 error_for_asm (insn, "output constraint %d must specify a single register", i);
528 for (j = 0; j < n_clobbers; j++)
529 if (REGNO (recog_data.operand[i]) == REGNO (clobber_reg[j]))
531 error_for_asm (insn, "output constraint %d cannot be specified together with \"%s\" clobber",
532 i, reg_names [REGNO (clobber_reg[j])]);
537 reg_used_as_output[REGNO (recog_data.operand[i])] = 1;
542 /* Search for first non-popped reg. */
543 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
544 if (! reg_used_as_output[i])
547 /* If there are any other popped regs, that's an error. */
548 for (; i < LAST_STACK_REG + 1; i++)
549 if (reg_used_as_output[i])
552 if (i != LAST_STACK_REG + 1)
554 error_for_asm (insn, "output regs must be grouped at top of stack");
558 /* Enforce rule #2: All implicitly popped input regs must be closer
559 to the top of the reg-stack than any input that is not implicitly
562 memset (implicitly_dies, 0, sizeof (implicitly_dies));
563 for (i = n_outputs; i < n_outputs + n_inputs; i++)
564 if (STACK_REG_P (recog_data.operand[i]))
566 /* An input reg is implicitly popped if it is tied to an
567 output, or if there is a CLOBBER for it. */
570 for (j = 0; j < n_clobbers; j++)
571 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
574 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
575 implicitly_dies[REGNO (recog_data.operand[i])] = 1;
578 /* Search for first non-popped reg. */
579 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
580 if (! implicitly_dies[i])
583 /* If there are any other popped regs, that's an error. */
584 for (; i < LAST_STACK_REG + 1; i++)
585 if (implicitly_dies[i])
588 if (i != LAST_STACK_REG + 1)
591 "implicitly popped regs must be grouped at top of stack");
595 /* Enforce rule #3: If any input operand uses the "f" constraint, all
596 output constraints must use the "&" earlyclobber.
598 ??? Detect this more deterministically by having constrain_asm_operands
599 record any earlyclobber. */
601 for (i = n_outputs; i < n_outputs + n_inputs; i++)
602 if (recog_op_alt[i][alt].matches == -1)
606 for (j = 0; j < n_outputs; j++)
607 if (operands_match_p (recog_data.operand[j], recog_data.operand[i]))
610 "output operand %d must use %<&%> constraint", j);
617 /* Avoid further trouble with this insn. */
618 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
619 any_malformed_asm = true;
626 /* Calculate the number of inputs and outputs in BODY, an
627 asm_operands. N_OPERANDS is the total number of operands, and
628 N_INPUTS and N_OUTPUTS are pointers to ints into which the results are
632 get_asm_operand_n_inputs (rtx body)
634 switch (GET_CODE (body))
637 gcc_assert (GET_CODE (SET_SRC (body)) == ASM_OPERANDS);
638 return ASM_OPERANDS_INPUT_LENGTH (SET_SRC (body));
641 return ASM_OPERANDS_INPUT_LENGTH (body);
644 return get_asm_operand_n_inputs (XVECEXP (body, 0, 0));
651 /* If current function returns its result in an fp stack register,
652 return the REG. Otherwise, return 0. */
655 stack_result (tree decl)
659 /* If the value is supposed to be returned in memory, then clearly
660 it is not returned in a stack register. */
661 if (aggregate_value_p (DECL_RESULT (decl), decl))
664 result = DECL_RTL_IF_SET (DECL_RESULT (decl));
667 #ifdef FUNCTION_OUTGOING_VALUE
669 = FUNCTION_OUTGOING_VALUE (TREE_TYPE (DECL_RESULT (decl)), decl);
671 result = FUNCTION_VALUE (TREE_TYPE (DECL_RESULT (decl)), decl);
675 return result != 0 && STACK_REG_P (result) ? result : 0;
680 * This section deals with stack register substitution, and forms the second
684 /* Replace REG, which is a pointer to a stack reg RTX, with an RTX for
685 the desired hard REGNO. */
688 replace_reg (rtx *reg, int regno)
690 gcc_assert (regno >= FIRST_STACK_REG);
691 gcc_assert (regno <= LAST_STACK_REG);
692 gcc_assert (STACK_REG_P (*reg));
694 gcc_assert (GET_MODE_CLASS (GET_MODE (*reg)) == MODE_FLOAT
695 || GET_MODE_CLASS (GET_MODE (*reg)) == MODE_COMPLEX_FLOAT);
697 *reg = FP_MODE_REG (regno, GET_MODE (*reg));
700 /* Remove a note of type NOTE, which must be found, for register
701 number REGNO from INSN. Remove only one such note. */
704 remove_regno_note (rtx insn, enum reg_note note, unsigned int regno)
706 rtx *note_link, this;
708 note_link = ®_NOTES (insn);
709 for (this = *note_link; this; this = XEXP (this, 1))
710 if (REG_NOTE_KIND (this) == note
711 && REG_P (XEXP (this, 0)) && REGNO (XEXP (this, 0)) == regno)
713 *note_link = XEXP (this, 1);
717 note_link = &XEXP (this, 1);
722 /* Find the hard register number of virtual register REG in REGSTACK.
723 The hard register number is relative to the top of the stack. -1 is
724 returned if the register is not found. */
727 get_hard_regnum (stack regstack, rtx reg)
731 gcc_assert (STACK_REG_P (reg));
733 for (i = regstack->top; i >= 0; i--)
734 if (regstack->reg[i] == REGNO (reg))
737 return i >= 0 ? (FIRST_STACK_REG + regstack->top - i) : -1;
740 /* Emit an insn to pop virtual register REG before or after INSN.
741 REGSTACK is the stack state after INSN and is updated to reflect this
742 pop. WHEN is either emit_insn_before or emit_insn_after. A pop insn
743 is represented as a SET whose destination is the register to be popped
744 and source is the top of stack. A death note for the top of stack
745 cases the movdf pattern to pop. */
748 emit_pop_insn (rtx insn, stack regstack, rtx reg, enum emit_where where)
750 rtx pop_insn, pop_rtx;
753 /* For complex types take care to pop both halves. These may survive in
754 CLOBBER and USE expressions. */
755 if (COMPLEX_MODE_P (GET_MODE (reg)))
757 rtx reg1 = FP_MODE_REG (REGNO (reg), DFmode);
758 rtx reg2 = FP_MODE_REG (REGNO (reg) + 1, DFmode);
761 if (get_hard_regnum (regstack, reg1) >= 0)
762 pop_insn = emit_pop_insn (insn, regstack, reg1, where);
763 if (get_hard_regnum (regstack, reg2) >= 0)
764 pop_insn = emit_pop_insn (insn, regstack, reg2, where);
765 gcc_assert (pop_insn);
769 hard_regno = get_hard_regnum (regstack, reg);
771 gcc_assert (hard_regno >= FIRST_STACK_REG);
773 pop_rtx = gen_rtx_SET (VOIDmode, FP_MODE_REG (hard_regno, DFmode),
774 FP_MODE_REG (FIRST_STACK_REG, DFmode));
776 if (where == EMIT_AFTER)
777 pop_insn = emit_insn_after (pop_rtx, insn);
779 pop_insn = emit_insn_before (pop_rtx, insn);
782 = gen_rtx_EXPR_LIST (REG_DEAD, FP_MODE_REG (FIRST_STACK_REG, DFmode),
783 REG_NOTES (pop_insn));
785 regstack->reg[regstack->top - (hard_regno - FIRST_STACK_REG)]
786 = regstack->reg[regstack->top];
788 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (reg));
793 /* Emit an insn before or after INSN to swap virtual register REG with
794 the top of stack. REGSTACK is the stack state before the swap, and
795 is updated to reflect the swap. A swap insn is represented as a
796 PARALLEL of two patterns: each pattern moves one reg to the other.
798 If REG is already at the top of the stack, no insn is emitted. */
801 emit_swap_insn (rtx insn, stack regstack, rtx reg)
805 int tmp, other_reg; /* swap regno temps */
806 rtx i1; /* the stack-reg insn prior to INSN */
807 rtx i1set = NULL_RTX; /* the SET rtx within I1 */
809 hard_regno = get_hard_regnum (regstack, reg);
811 gcc_assert (hard_regno >= FIRST_STACK_REG);
812 if (hard_regno == FIRST_STACK_REG)
815 other_reg = regstack->top - (hard_regno - FIRST_STACK_REG);
817 tmp = regstack->reg[other_reg];
818 regstack->reg[other_reg] = regstack->reg[regstack->top];
819 regstack->reg[regstack->top] = tmp;
821 /* Find the previous insn involving stack regs, but don't pass a
824 if (current_block && insn != BB_HEAD (current_block))
826 rtx tmp = PREV_INSN (insn);
827 rtx limit = PREV_INSN (BB_HEAD (current_block));
832 || NOTE_INSN_BASIC_BLOCK_P (tmp)
833 || (NONJUMP_INSN_P (tmp)
834 && stack_regs_mentioned (tmp)))
839 tmp = PREV_INSN (tmp);
844 && (i1set = single_set (i1)) != NULL_RTX)
846 rtx i1src = *get_true_reg (&SET_SRC (i1set));
847 rtx i1dest = *get_true_reg (&SET_DEST (i1set));
849 /* If the previous register stack push was from the reg we are to
850 swap with, omit the swap. */
852 if (REG_P (i1dest) && REGNO (i1dest) == FIRST_STACK_REG
854 && REGNO (i1src) == (unsigned) hard_regno - 1
855 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
858 /* If the previous insn wrote to the reg we are to swap with,
861 if (REG_P (i1dest) && REGNO (i1dest) == (unsigned) hard_regno
862 && REG_P (i1src) && REGNO (i1src) == FIRST_STACK_REG
863 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
867 swap_rtx = gen_swapxf (FP_MODE_REG (hard_regno, XFmode),
868 FP_MODE_REG (FIRST_STACK_REG, XFmode));
871 emit_insn_after (swap_rtx, i1);
872 else if (current_block)
873 emit_insn_before (swap_rtx, BB_HEAD (current_block));
875 emit_insn_before (swap_rtx, insn);
878 /* Emit an insns before INSN to swap virtual register SRC1 with
879 the top of stack and virtual register SRC2 with second stack
880 slot. REGSTACK is the stack state before the swaps, and
881 is updated to reflect the swaps. A swap insn is represented as a
882 PARALLEL of two patterns: each pattern moves one reg to the other.
884 If SRC1 and/or SRC2 are already at the right place, no swap insn
888 swap_to_top (rtx insn, stack regstack, rtx src1, rtx src2)
890 struct stack_def temp_stack;
891 int regno, j, k, temp;
893 temp_stack = *regstack;
895 /* Place operand 1 at the top of stack. */
896 regno = get_hard_regnum (&temp_stack, src1);
897 gcc_assert (regno >= 0);
898 if (regno != FIRST_STACK_REG)
900 k = temp_stack.top - (regno - FIRST_STACK_REG);
903 temp = temp_stack.reg[k];
904 temp_stack.reg[k] = temp_stack.reg[j];
905 temp_stack.reg[j] = temp;
908 /* Place operand 2 next on the stack. */
909 regno = get_hard_regnum (&temp_stack, src2);
910 gcc_assert (regno >= 0);
911 if (regno != FIRST_STACK_REG + 1)
913 k = temp_stack.top - (regno - FIRST_STACK_REG);
914 j = temp_stack.top - 1;
916 temp = temp_stack.reg[k];
917 temp_stack.reg[k] = temp_stack.reg[j];
918 temp_stack.reg[j] = temp;
921 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
924 /* Handle a move to or from a stack register in PAT, which is in INSN.
925 REGSTACK is the current stack. Return whether a control flow insn
926 was deleted in the process. */
929 move_for_stack_reg (rtx insn, stack regstack, rtx pat)
931 rtx *psrc = get_true_reg (&SET_SRC (pat));
932 rtx *pdest = get_true_reg (&SET_DEST (pat));
935 bool control_flow_insn_deleted = false;
937 src = *psrc; dest = *pdest;
939 if (STACK_REG_P (src) && STACK_REG_P (dest))
941 /* Write from one stack reg to another. If SRC dies here, then
942 just change the register mapping and delete the insn. */
944 note = find_regno_note (insn, REG_DEAD, REGNO (src));
949 /* If this is a no-op move, there must not be a REG_DEAD note. */
950 gcc_assert (REGNO (src) != REGNO (dest));
952 for (i = regstack->top; i >= 0; i--)
953 if (regstack->reg[i] == REGNO (src))
956 /* The destination must be dead, or life analysis is borked. */
957 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
959 /* If the source is not live, this is yet another case of
960 uninitialized variables. Load up a NaN instead. */
962 return move_nan_for_stack_reg (insn, regstack, dest);
964 /* It is possible that the dest is unused after this insn.
965 If so, just pop the src. */
967 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
968 emit_pop_insn (insn, regstack, src, EMIT_AFTER);
971 regstack->reg[i] = REGNO (dest);
972 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
973 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
976 control_flow_insn_deleted |= control_flow_insn_p (insn);
978 return control_flow_insn_deleted;
981 /* The source reg does not die. */
983 /* If this appears to be a no-op move, delete it, or else it
984 will confuse the machine description output patterns. But if
985 it is REG_UNUSED, we must pop the reg now, as per-insn processing
986 for REG_UNUSED will not work for deleted insns. */
988 if (REGNO (src) == REGNO (dest))
990 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
991 emit_pop_insn (insn, regstack, dest, EMIT_AFTER);
993 control_flow_insn_deleted |= control_flow_insn_p (insn);
995 return control_flow_insn_deleted;
998 /* The destination ought to be dead. */
999 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1001 replace_reg (psrc, get_hard_regnum (regstack, src));
1003 regstack->reg[++regstack->top] = REGNO (dest);
1004 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1005 replace_reg (pdest, FIRST_STACK_REG);
1007 else if (STACK_REG_P (src))
1009 /* Save from a stack reg to MEM, or possibly integer reg. Since
1010 only top of stack may be saved, emit an exchange first if
1013 emit_swap_insn (insn, regstack, src);
1015 note = find_regno_note (insn, REG_DEAD, REGNO (src));
1018 replace_reg (&XEXP (note, 0), FIRST_STACK_REG);
1020 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1022 else if ((GET_MODE (src) == XFmode)
1023 && regstack->top < REG_STACK_SIZE - 1)
1025 /* A 387 cannot write an XFmode value to a MEM without
1026 clobbering the source reg. The output code can handle
1027 this by reading back the value from the MEM.
1028 But it is more efficient to use a temp register if one is
1029 available. Push the source value here if the register
1030 stack is not full, and then write the value to memory via
1033 rtx top_stack_reg = FP_MODE_REG (FIRST_STACK_REG, GET_MODE (src));
1035 push_rtx = gen_movxf (top_stack_reg, top_stack_reg);
1036 emit_insn_before (push_rtx, insn);
1037 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_DEAD, top_stack_reg,
1041 replace_reg (psrc, FIRST_STACK_REG);
1045 gcc_assert (STACK_REG_P (dest));
1047 /* Load from MEM, or possibly integer REG or constant, into the
1048 stack regs. The actual target is always the top of the
1049 stack. The stack mapping is changed to reflect that DEST is
1050 now at top of stack. */
1052 /* The destination ought to be dead. */
1053 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1055 gcc_assert (regstack->top < REG_STACK_SIZE);
1057 regstack->reg[++regstack->top] = REGNO (dest);
1058 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1059 replace_reg (pdest, FIRST_STACK_REG);
1062 return control_flow_insn_deleted;
1065 /* A helper function which replaces INSN with a pattern that loads up
1066 a NaN into DEST, then invokes move_for_stack_reg. */
1069 move_nan_for_stack_reg (rtx insn, stack regstack, rtx dest)
1073 dest = FP_MODE_REG (REGNO (dest), SFmode);
1074 pat = gen_rtx_SET (VOIDmode, dest, not_a_num);
1075 PATTERN (insn) = pat;
1076 INSN_CODE (insn) = -1;
1078 return move_for_stack_reg (insn, regstack, pat);
1081 /* Swap the condition on a branch, if there is one. Return true if we
1082 found a condition to swap. False if the condition was not used as
1086 swap_rtx_condition_1 (rtx pat)
1091 if (COMPARISON_P (pat))
1093 PUT_CODE (pat, swap_condition (GET_CODE (pat)));
1098 fmt = GET_RTX_FORMAT (GET_CODE (pat));
1099 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
1105 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
1106 r |= swap_rtx_condition_1 (XVECEXP (pat, i, j));
1108 else if (fmt[i] == 'e')
1109 r |= swap_rtx_condition_1 (XEXP (pat, i));
1117 swap_rtx_condition (rtx insn)
1119 rtx pat = PATTERN (insn);
1121 /* We're looking for a single set to cc0 or an HImode temporary. */
1123 if (GET_CODE (pat) == SET
1124 && REG_P (SET_DEST (pat))
1125 && REGNO (SET_DEST (pat)) == FLAGS_REG)
1127 insn = next_flags_user (insn);
1128 if (insn == NULL_RTX)
1130 pat = PATTERN (insn);
1133 /* See if this is, or ends in, a fnstsw. If so, we're not doing anything
1134 with the cc value right now. We may be able to search for one
1137 if (GET_CODE (pat) == SET
1138 && GET_CODE (SET_SRC (pat)) == UNSPEC
1139 && XINT (SET_SRC (pat), 1) == UNSPEC_FNSTSW)
1141 rtx dest = SET_DEST (pat);
1143 /* Search forward looking for the first use of this value.
1144 Stop at block boundaries. */
1145 while (insn != BB_END (current_block))
1147 insn = NEXT_INSN (insn);
1148 if (INSN_P (insn) && reg_mentioned_p (dest, insn))
1154 /* We haven't found it. */
1155 if (insn == BB_END (current_block))
1158 /* So we've found the insn using this value. If it is anything
1159 other than sahf or the value does not die (meaning we'd have
1160 to search further), then we must give up. */
1161 pat = PATTERN (insn);
1162 if (GET_CODE (pat) != SET
1163 || GET_CODE (SET_SRC (pat)) != UNSPEC
1164 || XINT (SET_SRC (pat), 1) != UNSPEC_SAHF
1165 || ! dead_or_set_p (insn, dest))
1168 /* Now we are prepared to handle this as a normal cc0 setter. */
1169 insn = next_flags_user (insn);
1170 if (insn == NULL_RTX)
1172 pat = PATTERN (insn);
1175 if (swap_rtx_condition_1 (pat))
1178 INSN_CODE (insn) = -1;
1179 if (recog_memoized (insn) == -1)
1181 /* In case the flags don't die here, recurse to try fix
1182 following user too. */
1183 else if (! dead_or_set_p (insn, ix86_flags_rtx))
1185 insn = next_flags_user (insn);
1186 if (!insn || !swap_rtx_condition (insn))
1191 swap_rtx_condition_1 (pat);
1199 /* Handle a comparison. Special care needs to be taken to avoid
1200 causing comparisons that a 387 cannot do correctly, such as EQ.
1202 Also, a pop insn may need to be emitted. The 387 does have an
1203 `fcompp' insn that can pop two regs, but it is sometimes too expensive
1204 to do this - a `fcomp' followed by a `fstpl %st(0)' may be easier to
1208 compare_for_stack_reg (rtx insn, stack regstack, rtx pat_src)
1211 rtx src1_note, src2_note;
1213 src1 = get_true_reg (&XEXP (pat_src, 0));
1214 src2 = get_true_reg (&XEXP (pat_src, 1));
1216 /* ??? If fxch turns out to be cheaper than fstp, give priority to
1217 registers that die in this insn - move those to stack top first. */
1218 if ((! STACK_REG_P (*src1)
1219 || (STACK_REG_P (*src2)
1220 && get_hard_regnum (regstack, *src2) == FIRST_STACK_REG))
1221 && swap_rtx_condition (insn))
1224 temp = XEXP (pat_src, 0);
1225 XEXP (pat_src, 0) = XEXP (pat_src, 1);
1226 XEXP (pat_src, 1) = temp;
1228 src1 = get_true_reg (&XEXP (pat_src, 0));
1229 src2 = get_true_reg (&XEXP (pat_src, 1));
1231 INSN_CODE (insn) = -1;
1234 /* We will fix any death note later. */
1236 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1238 if (STACK_REG_P (*src2))
1239 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1241 src2_note = NULL_RTX;
1243 emit_swap_insn (insn, regstack, *src1);
1245 replace_reg (src1, FIRST_STACK_REG);
1247 if (STACK_REG_P (*src2))
1248 replace_reg (src2, get_hard_regnum (regstack, *src2));
1252 pop_stack (regstack, REGNO (XEXP (src1_note, 0)));
1253 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1256 /* If the second operand dies, handle that. But if the operands are
1257 the same stack register, don't bother, because only one death is
1258 needed, and it was just handled. */
1261 && ! (STACK_REG_P (*src1) && STACK_REG_P (*src2)
1262 && REGNO (*src1) == REGNO (*src2)))
1264 /* As a special case, two regs may die in this insn if src2 is
1265 next to top of stack and the top of stack also dies. Since
1266 we have already popped src1, "next to top of stack" is really
1267 at top (FIRST_STACK_REG) now. */
1269 if (get_hard_regnum (regstack, XEXP (src2_note, 0)) == FIRST_STACK_REG
1272 pop_stack (regstack, REGNO (XEXP (src2_note, 0)));
1273 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1277 /* The 386 can only represent death of the first operand in
1278 the case handled above. In all other cases, emit a separate
1279 pop and remove the death note from here. */
1281 /* link_cc0_insns (insn); */
1283 remove_regno_note (insn, REG_DEAD, REGNO (XEXP (src2_note, 0)));
1285 emit_pop_insn (insn, regstack, XEXP (src2_note, 0),
1291 /* Substitute new registers in PAT, which is part of INSN. REGSTACK
1292 is the current register layout. Return whether a control flow insn
1293 was deleted in the process. */
1296 subst_stack_regs_pat (rtx insn, stack regstack, rtx pat)
1299 bool control_flow_insn_deleted = false;
1301 switch (GET_CODE (pat))
1304 /* Deaths in USE insns can happen in non optimizing compilation.
1305 Handle them by popping the dying register. */
1306 src = get_true_reg (&XEXP (pat, 0));
1307 if (STACK_REG_P (*src)
1308 && find_regno_note (insn, REG_DEAD, REGNO (*src)))
1310 emit_pop_insn (insn, regstack, *src, EMIT_AFTER);
1311 return control_flow_insn_deleted;
1313 /* ??? Uninitialized USE should not happen. */
1315 gcc_assert (get_hard_regnum (regstack, *src) != -1);
1322 dest = get_true_reg (&XEXP (pat, 0));
1323 if (STACK_REG_P (*dest))
1325 note = find_reg_note (insn, REG_DEAD, *dest);
1327 if (pat != PATTERN (insn))
1329 /* The fix_truncdi_1 pattern wants to be able to allocate
1330 its own scratch register. It does this by clobbering
1331 an fp reg so that it is assured of an empty reg-stack
1332 register. If the register is live, kill it now.
1333 Remove the DEAD/UNUSED note so we don't try to kill it
1337 emit_pop_insn (insn, regstack, *dest, EMIT_BEFORE);
1340 note = find_reg_note (insn, REG_UNUSED, *dest);
1343 remove_note (insn, note);
1344 replace_reg (dest, FIRST_STACK_REG + 1);
1348 /* A top-level clobber with no REG_DEAD, and no hard-regnum
1349 indicates an uninitialized value. Because reload removed
1350 all other clobbers, this must be due to a function
1351 returning without a value. Load up a NaN. */
1356 if (get_hard_regnum (regstack, t) == -1)
1357 control_flow_insn_deleted
1358 |= move_nan_for_stack_reg (insn, regstack, t);
1359 if (COMPLEX_MODE_P (GET_MODE (t)))
1361 t = FP_MODE_REG (REGNO (t) + 1, DFmode);
1362 if (get_hard_regnum (regstack, t) == -1)
1363 control_flow_insn_deleted
1364 |= move_nan_for_stack_reg (insn, regstack, t);
1374 rtx *src1 = (rtx *) 0, *src2;
1375 rtx src1_note, src2_note;
1378 dest = get_true_reg (&SET_DEST (pat));
1379 src = get_true_reg (&SET_SRC (pat));
1380 pat_src = SET_SRC (pat);
1382 /* See if this is a `movM' pattern, and handle elsewhere if so. */
1383 if (STACK_REG_P (*src)
1384 || (STACK_REG_P (*dest)
1385 && (REG_P (*src) || MEM_P (*src)
1386 || GET_CODE (*src) == CONST_DOUBLE)))
1388 control_flow_insn_deleted |= move_for_stack_reg (insn, regstack, pat);
1392 switch (GET_CODE (pat_src))
1395 compare_for_stack_reg (insn, regstack, pat_src);
1401 for (count = hard_regno_nregs[REGNO (*dest)][GET_MODE (*dest)];
1404 regstack->reg[++regstack->top] = REGNO (*dest) + count;
1405 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest) + count);
1408 replace_reg (dest, FIRST_STACK_REG);
1412 /* This is a `tstM2' case. */
1413 gcc_assert (*dest == cc0_rtx);
1418 case FLOAT_TRUNCATE:
1422 /* These insns only operate on the top of the stack. DEST might
1423 be cc0_rtx if we're processing a tstM pattern. Also, it's
1424 possible that the tstM case results in a REG_DEAD note on the
1428 src1 = get_true_reg (&XEXP (pat_src, 0));
1430 emit_swap_insn (insn, regstack, *src1);
1432 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1434 if (STACK_REG_P (*dest))
1435 replace_reg (dest, FIRST_STACK_REG);
1439 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1441 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1444 replace_reg (src1, FIRST_STACK_REG);
1449 /* On i386, reversed forms of subM3 and divM3 exist for
1450 MODE_FLOAT, so the same code that works for addM3 and mulM3
1454 /* These insns can accept the top of stack as a destination
1455 from a stack reg or mem, or can use the top of stack as a
1456 source and some other stack register (possibly top of stack)
1457 as a destination. */
1459 src1 = get_true_reg (&XEXP (pat_src, 0));
1460 src2 = get_true_reg (&XEXP (pat_src, 1));
1462 /* We will fix any death note later. */
1464 if (STACK_REG_P (*src1))
1465 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1467 src1_note = NULL_RTX;
1468 if (STACK_REG_P (*src2))
1469 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1471 src2_note = NULL_RTX;
1473 /* If either operand is not a stack register, then the dest
1474 must be top of stack. */
1476 if (! STACK_REG_P (*src1) || ! STACK_REG_P (*src2))
1477 emit_swap_insn (insn, regstack, *dest);
1480 /* Both operands are REG. If neither operand is already
1481 at the top of stack, choose to make the one that is the dest
1482 the new top of stack. */
1484 int src1_hard_regnum, src2_hard_regnum;
1486 src1_hard_regnum = get_hard_regnum (regstack, *src1);
1487 src2_hard_regnum = get_hard_regnum (regstack, *src2);
1488 gcc_assert (src1_hard_regnum != -1);
1489 gcc_assert (src2_hard_regnum != -1);
1491 if (src1_hard_regnum != FIRST_STACK_REG
1492 && src2_hard_regnum != FIRST_STACK_REG)
1493 emit_swap_insn (insn, regstack, *dest);
1496 if (STACK_REG_P (*src1))
1497 replace_reg (src1, get_hard_regnum (regstack, *src1));
1498 if (STACK_REG_P (*src2))
1499 replace_reg (src2, get_hard_regnum (regstack, *src2));
1503 rtx src1_reg = XEXP (src1_note, 0);
1505 /* If the register that dies is at the top of stack, then
1506 the destination is somewhere else - merely substitute it.
1507 But if the reg that dies is not at top of stack, then
1508 move the top of stack to the dead reg, as though we had
1509 done the insn and then a store-with-pop. */
1511 if (REGNO (src1_reg) == regstack->reg[regstack->top])
1513 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1514 replace_reg (dest, get_hard_regnum (regstack, *dest));
1518 int regno = get_hard_regnum (regstack, src1_reg);
1520 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1521 replace_reg (dest, regno);
1523 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1524 = regstack->reg[regstack->top];
1527 CLEAR_HARD_REG_BIT (regstack->reg_set,
1528 REGNO (XEXP (src1_note, 0)));
1529 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1534 rtx src2_reg = XEXP (src2_note, 0);
1535 if (REGNO (src2_reg) == regstack->reg[regstack->top])
1537 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1538 replace_reg (dest, get_hard_regnum (regstack, *dest));
1542 int regno = get_hard_regnum (regstack, src2_reg);
1544 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1545 replace_reg (dest, regno);
1547 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1548 = regstack->reg[regstack->top];
1551 CLEAR_HARD_REG_BIT (regstack->reg_set,
1552 REGNO (XEXP (src2_note, 0)));
1553 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG);
1558 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1559 replace_reg (dest, get_hard_regnum (regstack, *dest));
1562 /* Keep operand 1 matching with destination. */
1563 if (COMMUTATIVE_ARITH_P (pat_src)
1564 && REG_P (*src1) && REG_P (*src2)
1565 && REGNO (*src1) != REGNO (*dest))
1567 int tmp = REGNO (*src1);
1568 replace_reg (src1, REGNO (*src2));
1569 replace_reg (src2, tmp);
1574 switch (XINT (pat_src, 1))
1578 case UNSPEC_FIST_FLOOR:
1579 case UNSPEC_FIST_CEIL:
1581 /* These insns only operate on the top of the stack. */
1583 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1584 emit_swap_insn (insn, regstack, *src1);
1586 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1588 if (STACK_REG_P (*dest))
1589 replace_reg (dest, FIRST_STACK_REG);
1593 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1595 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1598 replace_reg (src1, FIRST_STACK_REG);
1603 case UNSPEC_FRNDINT:
1606 case UNSPEC_FRNDINT_FLOOR:
1607 case UNSPEC_FRNDINT_CEIL:
1608 case UNSPEC_FRNDINT_TRUNC:
1609 case UNSPEC_FRNDINT_MASK_PM:
1611 /* These insns only operate on the top of the stack. */
1613 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1615 emit_swap_insn (insn, regstack, *src1);
1617 /* Input should never die, it is
1618 replaced with output. */
1619 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1620 gcc_assert (!src1_note);
1622 if (STACK_REG_P (*dest))
1623 replace_reg (dest, FIRST_STACK_REG);
1625 replace_reg (src1, FIRST_STACK_REG);
1630 case UNSPEC_FYL2XP1:
1631 /* These insns operate on the top two stack slots. */
1633 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1634 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1636 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1637 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1639 swap_to_top (insn, regstack, *src1, *src2);
1641 replace_reg (src1, FIRST_STACK_REG);
1642 replace_reg (src2, FIRST_STACK_REG + 1);
1645 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1647 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1649 /* Pop both input operands from the stack. */
1650 CLEAR_HARD_REG_BIT (regstack->reg_set,
1651 regstack->reg[regstack->top]);
1652 CLEAR_HARD_REG_BIT (regstack->reg_set,
1653 regstack->reg[regstack->top - 1]);
1656 /* Push the result back onto the stack. */
1657 regstack->reg[++regstack->top] = REGNO (*dest);
1658 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1659 replace_reg (dest, FIRST_STACK_REG);
1662 case UNSPEC_FSCALE_FRACT:
1663 case UNSPEC_FPREM_F:
1664 case UNSPEC_FPREM1_F:
1665 /* These insns operate on the top two stack slots.
1666 first part of double input, double output insn. */
1668 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1669 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1671 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1672 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1674 /* Inputs should never die, they are
1675 replaced with outputs. */
1676 gcc_assert (!src1_note);
1677 gcc_assert (!src2_note);
1679 swap_to_top (insn, regstack, *src1, *src2);
1681 /* Push the result back onto stack. Empty stack slot
1682 will be filled in second part of insn. */
1683 if (STACK_REG_P (*dest)) {
1684 regstack->reg[regstack->top] = REGNO (*dest);
1685 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1686 replace_reg (dest, FIRST_STACK_REG);
1689 replace_reg (src1, FIRST_STACK_REG);
1690 replace_reg (src2, FIRST_STACK_REG + 1);
1693 case UNSPEC_FSCALE_EXP:
1694 case UNSPEC_FPREM_U:
1695 case UNSPEC_FPREM1_U:
1696 /* These insns operate on the top two stack slots./
1697 second part of double input, double output insn. */
1699 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1700 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1702 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1703 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1705 /* Inputs should never die, they are
1706 replaced with outputs. */
1707 gcc_assert (!src1_note);
1708 gcc_assert (!src2_note);
1710 swap_to_top (insn, regstack, *src1, *src2);
1712 /* Push the result back onto stack. Fill empty slot from
1713 first part of insn and fix top of stack pointer. */
1714 if (STACK_REG_P (*dest)) {
1715 regstack->reg[regstack->top - 1] = REGNO (*dest);
1716 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1717 replace_reg (dest, FIRST_STACK_REG + 1);
1720 replace_reg (src1, FIRST_STACK_REG);
1721 replace_reg (src2, FIRST_STACK_REG + 1);
1724 case UNSPEC_SINCOS_COS:
1725 case UNSPEC_TAN_ONE:
1726 case UNSPEC_XTRACT_FRACT:
1727 /* These insns operate on the top two stack slots,
1728 first part of one input, double output insn. */
1730 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1732 emit_swap_insn (insn, regstack, *src1);
1734 /* Input should never die, it is
1735 replaced with output. */
1736 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1737 gcc_assert (!src1_note);
1739 /* Push the result back onto stack. Empty stack slot
1740 will be filled in second part of insn. */
1741 if (STACK_REG_P (*dest)) {
1742 regstack->reg[regstack->top + 1] = REGNO (*dest);
1743 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1744 replace_reg (dest, FIRST_STACK_REG);
1747 replace_reg (src1, FIRST_STACK_REG);
1750 case UNSPEC_SINCOS_SIN:
1751 case UNSPEC_TAN_TAN:
1752 case UNSPEC_XTRACT_EXP:
1753 /* These insns operate on the top two stack slots,
1754 second part of one input, double output insn. */
1756 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1758 emit_swap_insn (insn, regstack, *src1);
1760 /* Input should never die, it is
1761 replaced with output. */
1762 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1763 gcc_assert (!src1_note);
1765 /* Push the result back onto stack. Fill empty slot from
1766 first part of insn and fix top of stack pointer. */
1767 if (STACK_REG_P (*dest)) {
1768 regstack->reg[regstack->top] = REGNO (*dest);
1769 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1770 replace_reg (dest, FIRST_STACK_REG + 1);
1775 replace_reg (src1, FIRST_STACK_REG);
1779 /* (unspec [(unspec [(compare)] UNSPEC_FNSTSW)] UNSPEC_SAHF)
1780 The combination matches the PPRO fcomi instruction. */
1782 pat_src = XVECEXP (pat_src, 0, 0);
1783 gcc_assert (GET_CODE (pat_src) == UNSPEC);
1784 gcc_assert (XINT (pat_src, 1) == UNSPEC_FNSTSW);
1788 /* Combined fcomp+fnstsw generated for doing well with
1789 CSE. When optimizing this would have been broken
1792 pat_src = XVECEXP (pat_src, 0, 0);
1793 gcc_assert (GET_CODE (pat_src) == COMPARE);
1795 compare_for_stack_reg (insn, regstack, pat_src);
1804 /* This insn requires the top of stack to be the destination. */
1806 src1 = get_true_reg (&XEXP (pat_src, 1));
1807 src2 = get_true_reg (&XEXP (pat_src, 2));
1809 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1810 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1812 /* If the comparison operator is an FP comparison operator,
1813 it is handled correctly by compare_for_stack_reg () who
1814 will move the destination to the top of stack. But if the
1815 comparison operator is not an FP comparison operator, we
1816 have to handle it here. */
1817 if (get_hard_regnum (regstack, *dest) >= FIRST_STACK_REG
1818 && REGNO (*dest) != regstack->reg[regstack->top])
1820 /* In case one of operands is the top of stack and the operands
1821 dies, it is safe to make it the destination operand by
1822 reversing the direction of cmove and avoid fxch. */
1823 if ((REGNO (*src1) == regstack->reg[regstack->top]
1825 || (REGNO (*src2) == regstack->reg[regstack->top]
1828 int idx1 = (get_hard_regnum (regstack, *src1)
1830 int idx2 = (get_hard_regnum (regstack, *src2)
1833 /* Make reg-stack believe that the operands are already
1834 swapped on the stack */
1835 regstack->reg[regstack->top - idx1] = REGNO (*src2);
1836 regstack->reg[regstack->top - idx2] = REGNO (*src1);
1838 /* Reverse condition to compensate the operand swap.
1839 i386 do have comparison always reversible. */
1840 PUT_CODE (XEXP (pat_src, 0),
1841 reversed_comparison_code (XEXP (pat_src, 0), insn));
1844 emit_swap_insn (insn, regstack, *dest);
1852 src_note[1] = src1_note;
1853 src_note[2] = src2_note;
1855 if (STACK_REG_P (*src1))
1856 replace_reg (src1, get_hard_regnum (regstack, *src1));
1857 if (STACK_REG_P (*src2))
1858 replace_reg (src2, get_hard_regnum (regstack, *src2));
1860 for (i = 1; i <= 2; i++)
1863 int regno = REGNO (XEXP (src_note[i], 0));
1865 /* If the register that dies is not at the top of
1866 stack, then move the top of stack to the dead reg.
1867 Top of stack should never die, as it is the
1869 gcc_assert (regno != regstack->reg[regstack->top]);
1870 remove_regno_note (insn, REG_DEAD, regno);
1871 emit_pop_insn (insn, regstack, XEXP (src_note[i], 0),
1876 /* Make dest the top of stack. Add dest to regstack if
1878 if (get_hard_regnum (regstack, *dest) < FIRST_STACK_REG)
1879 regstack->reg[++regstack->top] = REGNO (*dest);
1880 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1881 replace_reg (dest, FIRST_STACK_REG);
1894 return control_flow_insn_deleted;
1897 /* Substitute hard regnums for any stack regs in INSN, which has
1898 N_INPUTS inputs and N_OUTPUTS outputs. REGSTACK is the stack info
1899 before the insn, and is updated with changes made here.
1901 There are several requirements and assumptions about the use of
1902 stack-like regs in asm statements. These rules are enforced by
1903 record_asm_stack_regs; see comments there for details. Any
1904 asm_operands left in the RTL at this point may be assume to meet the
1905 requirements, since record_asm_stack_regs removes any problem asm. */
1908 subst_asm_stack_regs (rtx insn, stack regstack)
1910 rtx body = PATTERN (insn);
1913 rtx *note_reg; /* Array of note contents */
1914 rtx **note_loc; /* Address of REG field of each note */
1915 enum reg_note *note_kind; /* The type of each note */
1917 rtx *clobber_reg = 0;
1918 rtx **clobber_loc = 0;
1920 struct stack_def temp_stack;
1925 int n_inputs, n_outputs;
1927 if (! check_asm_stack_operands (insn))
1930 /* Find out what the constraints required. If no constraint
1931 alternative matches, that is a compiler bug: we should have caught
1932 such an insn in check_asm_stack_operands. */
1933 extract_insn (insn);
1934 constrain_operands (1);
1935 alt = which_alternative;
1937 preprocess_constraints ();
1939 n_inputs = get_asm_operand_n_inputs (body);
1940 n_outputs = recog_data.n_operands - n_inputs;
1942 gcc_assert (alt >= 0);
1944 /* Strip SUBREGs here to make the following code simpler. */
1945 for (i = 0; i < recog_data.n_operands; i++)
1946 if (GET_CODE (recog_data.operand[i]) == SUBREG
1947 && REG_P (SUBREG_REG (recog_data.operand[i])))
1949 recog_data.operand_loc[i] = & SUBREG_REG (recog_data.operand[i]);
1950 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
1953 /* Set up NOTE_REG, NOTE_LOC and NOTE_KIND. */
1955 for (i = 0, note = REG_NOTES (insn); note; note = XEXP (note, 1))
1958 note_reg = alloca (i * sizeof (rtx));
1959 note_loc = alloca (i * sizeof (rtx *));
1960 note_kind = alloca (i * sizeof (enum reg_note));
1963 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
1965 rtx reg = XEXP (note, 0);
1966 rtx *loc = & XEXP (note, 0);
1968 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
1970 loc = & SUBREG_REG (reg);
1971 reg = SUBREG_REG (reg);
1974 if (STACK_REG_P (reg)
1975 && (REG_NOTE_KIND (note) == REG_DEAD
1976 || REG_NOTE_KIND (note) == REG_UNUSED))
1978 note_reg[n_notes] = reg;
1979 note_loc[n_notes] = loc;
1980 note_kind[n_notes] = REG_NOTE_KIND (note);
1985 /* Set up CLOBBER_REG and CLOBBER_LOC. */
1989 if (GET_CODE (body) == PARALLEL)
1991 clobber_reg = alloca (XVECLEN (body, 0) * sizeof (rtx));
1992 clobber_loc = alloca (XVECLEN (body, 0) * sizeof (rtx *));
1994 for (i = 0; i < XVECLEN (body, 0); i++)
1995 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
1997 rtx clobber = XVECEXP (body, 0, i);
1998 rtx reg = XEXP (clobber, 0);
1999 rtx *loc = & XEXP (clobber, 0);
2001 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
2003 loc = & SUBREG_REG (reg);
2004 reg = SUBREG_REG (reg);
2007 if (STACK_REG_P (reg))
2009 clobber_reg[n_clobbers] = reg;
2010 clobber_loc[n_clobbers] = loc;
2016 temp_stack = *regstack;
2018 /* Put the input regs into the desired place in TEMP_STACK. */
2020 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2021 if (STACK_REG_P (recog_data.operand[i])
2022 && reg_class_subset_p (recog_op_alt[i][alt].cl,
2024 && recog_op_alt[i][alt].cl != FLOAT_REGS)
2026 /* If an operand needs to be in a particular reg in
2027 FLOAT_REGS, the constraint was either 't' or 'u'. Since
2028 these constraints are for single register classes, and
2029 reload guaranteed that operand[i] is already in that class,
2030 we can just use REGNO (recog_data.operand[i]) to know which
2031 actual reg this operand needs to be in. */
2033 int regno = get_hard_regnum (&temp_stack, recog_data.operand[i]);
2035 gcc_assert (regno >= 0);
2037 if ((unsigned int) regno != REGNO (recog_data.operand[i]))
2039 /* recog_data.operand[i] is not in the right place. Find
2040 it and swap it with whatever is already in I's place.
2041 K is where recog_data.operand[i] is now. J is where it
2045 k = temp_stack.top - (regno - FIRST_STACK_REG);
2047 - (REGNO (recog_data.operand[i]) - FIRST_STACK_REG));
2049 temp = temp_stack.reg[k];
2050 temp_stack.reg[k] = temp_stack.reg[j];
2051 temp_stack.reg[j] = temp;
2055 /* Emit insns before INSN to make sure the reg-stack is in the right
2058 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
2060 /* Make the needed input register substitutions. Do death notes and
2061 clobbers too, because these are for inputs, not outputs. */
2063 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2064 if (STACK_REG_P (recog_data.operand[i]))
2066 int regnum = get_hard_regnum (regstack, recog_data.operand[i]);
2068 gcc_assert (regnum >= 0);
2070 replace_reg (recog_data.operand_loc[i], regnum);
2073 for (i = 0; i < n_notes; i++)
2074 if (note_kind[i] == REG_DEAD)
2076 int regnum = get_hard_regnum (regstack, note_reg[i]);
2078 gcc_assert (regnum >= 0);
2080 replace_reg (note_loc[i], regnum);
2083 for (i = 0; i < n_clobbers; i++)
2085 /* It's OK for a CLOBBER to reference a reg that is not live.
2086 Don't try to replace it in that case. */
2087 int regnum = get_hard_regnum (regstack, clobber_reg[i]);
2091 /* Sigh - clobbers always have QImode. But replace_reg knows
2092 that these regs can't be MODE_INT and will assert. Just put
2093 the right reg there without calling replace_reg. */
2095 *clobber_loc[i] = FP_MODE_REG (regnum, DFmode);
2099 /* Now remove from REGSTACK any inputs that the asm implicitly popped. */
2101 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2102 if (STACK_REG_P (recog_data.operand[i]))
2104 /* An input reg is implicitly popped if it is tied to an
2105 output, or if there is a CLOBBER for it. */
2108 for (j = 0; j < n_clobbers; j++)
2109 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
2112 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
2114 /* recog_data.operand[i] might not be at the top of stack.
2115 But that's OK, because all we need to do is pop the
2116 right number of regs off of the top of the reg-stack.
2117 record_asm_stack_regs guaranteed that all implicitly
2118 popped regs were grouped at the top of the reg-stack. */
2120 CLEAR_HARD_REG_BIT (regstack->reg_set,
2121 regstack->reg[regstack->top]);
2126 /* Now add to REGSTACK any outputs that the asm implicitly pushed.
2127 Note that there isn't any need to substitute register numbers.
2128 ??? Explain why this is true. */
2130 for (i = LAST_STACK_REG; i >= FIRST_STACK_REG; i--)
2132 /* See if there is an output for this hard reg. */
2135 for (j = 0; j < n_outputs; j++)
2136 if (STACK_REG_P (recog_data.operand[j])
2137 && REGNO (recog_data.operand[j]) == (unsigned) i)
2139 regstack->reg[++regstack->top] = i;
2140 SET_HARD_REG_BIT (regstack->reg_set, i);
2145 /* Now emit a pop insn for any REG_UNUSED output, or any REG_DEAD
2146 input that the asm didn't implicitly pop. If the asm didn't
2147 implicitly pop an input reg, that reg will still be live.
2149 Note that we can't use find_regno_note here: the register numbers
2150 in the death notes have already been substituted. */
2152 for (i = 0; i < n_outputs; i++)
2153 if (STACK_REG_P (recog_data.operand[i]))
2157 for (j = 0; j < n_notes; j++)
2158 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2159 && note_kind[j] == REG_UNUSED)
2161 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2167 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2168 if (STACK_REG_P (recog_data.operand[i]))
2172 for (j = 0; j < n_notes; j++)
2173 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2174 && note_kind[j] == REG_DEAD
2175 && TEST_HARD_REG_BIT (regstack->reg_set,
2176 REGNO (recog_data.operand[i])))
2178 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2185 /* Substitute stack hard reg numbers for stack virtual registers in
2186 INSN. Non-stack register numbers are not changed. REGSTACK is the
2187 current stack content. Insns may be emitted as needed to arrange the
2188 stack for the 387 based on the contents of the insn. Return whether
2189 a control flow insn was deleted in the process. */
2192 subst_stack_regs (rtx insn, stack regstack)
2194 rtx *note_link, note;
2195 bool control_flow_insn_deleted = false;
2200 int top = regstack->top;
2202 /* If there are any floating point parameters to be passed in
2203 registers for this call, make sure they are in the right
2208 straighten_stack (PREV_INSN (insn), regstack);
2210 /* Now mark the arguments as dead after the call. */
2212 while (regstack->top >= 0)
2214 CLEAR_HARD_REG_BIT (regstack->reg_set, FIRST_STACK_REG + regstack->top);
2220 /* Do the actual substitution if any stack regs are mentioned.
2221 Since we only record whether entire insn mentions stack regs, and
2222 subst_stack_regs_pat only works for patterns that contain stack regs,
2223 we must check each pattern in a parallel here. A call_value_pop could
2226 if (stack_regs_mentioned (insn))
2228 int n_operands = asm_noperands (PATTERN (insn));
2229 if (n_operands >= 0)
2231 /* This insn is an `asm' with operands. Decode the operands,
2232 decide how many are inputs, and do register substitution.
2233 Any REG_UNUSED notes will be handled by subst_asm_stack_regs. */
2235 subst_asm_stack_regs (insn, regstack);
2236 return control_flow_insn_deleted;
2239 if (GET_CODE (PATTERN (insn)) == PARALLEL)
2240 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
2242 if (stack_regs_mentioned_p (XVECEXP (PATTERN (insn), 0, i)))
2244 if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == CLOBBER)
2245 XVECEXP (PATTERN (insn), 0, i)
2246 = shallow_copy_rtx (XVECEXP (PATTERN (insn), 0, i));
2247 control_flow_insn_deleted
2248 |= subst_stack_regs_pat (insn, regstack,
2249 XVECEXP (PATTERN (insn), 0, i));
2253 control_flow_insn_deleted
2254 |= subst_stack_regs_pat (insn, regstack, PATTERN (insn));
2257 /* subst_stack_regs_pat may have deleted a no-op insn. If so, any
2258 REG_UNUSED will already have been dealt with, so just return. */
2260 if (NOTE_P (insn) || INSN_DELETED_P (insn))
2261 return control_flow_insn_deleted;
2263 /* If there is a REG_UNUSED note on a stack register on this insn,
2264 the indicated reg must be popped. The REG_UNUSED note is removed,
2265 since the form of the newly emitted pop insn references the reg,
2266 making it no longer `unset'. */
2268 note_link = ®_NOTES (insn);
2269 for (note = *note_link; note; note = XEXP (note, 1))
2270 if (REG_NOTE_KIND (note) == REG_UNUSED && STACK_REG_P (XEXP (note, 0)))
2272 *note_link = XEXP (note, 1);
2273 insn = emit_pop_insn (insn, regstack, XEXP (note, 0), EMIT_AFTER);
2276 note_link = &XEXP (note, 1);
2278 return control_flow_insn_deleted;
2281 /* Change the organization of the stack so that it fits a new basic
2282 block. Some registers might have to be popped, but there can never be
2283 a register live in the new block that is not now live.
2285 Insert any needed insns before or after INSN, as indicated by
2286 WHERE. OLD is the original stack layout, and NEW is the desired
2287 form. OLD is updated to reflect the code emitted, i.e., it will be
2288 the same as NEW upon return.
2290 This function will not preserve block_end[]. But that information
2291 is no longer needed once this has executed. */
2294 change_stack (rtx insn, stack old, stack new, enum emit_where where)
2299 /* We will be inserting new insns "backwards". If we are to insert
2300 after INSN, find the next insn, and insert before it. */
2302 if (where == EMIT_AFTER)
2304 if (current_block && BB_END (current_block) == insn)
2306 insn = NEXT_INSN (insn);
2309 /* Pop any registers that are not needed in the new block. */
2311 /* If the destination block's stack already has a specified layout
2312 and contains two or more registers, use a more intelligent algorithm
2313 to pop registers that minimizes the number number of fxchs below. */
2316 bool slots[REG_STACK_SIZE];
2317 int pops[REG_STACK_SIZE];
2318 int next, dest, topsrc;
2320 /* First pass to determine the free slots. */
2321 for (reg = 0; reg <= new->top; reg++)
2322 slots[reg] = TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]);
2324 /* Second pass to allocate preferred slots. */
2326 for (reg = old->top; reg > new->top; reg--)
2327 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2330 for (next = 0; next <= new->top; next++)
2331 if (!slots[next] && new->reg[next] == old->reg[reg])
2333 /* If this is a preference for the new top of stack, record
2334 the fact by remembering it's old->reg in topsrc. */
2335 if (next == new->top)
2346 /* Intentionally, avoid placing the top of stack in it's correct
2347 location, if we still need to permute the stack below and we
2348 can usefully place it somewhere else. This is the case if any
2349 slot is still unallocated, in which case we should place the
2350 top of stack there. */
2352 for (reg = 0; reg < new->top; reg++)
2356 slots[new->top] = false;
2361 /* Third pass allocates remaining slots and emits pop insns. */
2363 for (reg = old->top; reg > new->top; reg--)
2368 /* Find next free slot. */
2373 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[dest], DFmode),
2379 /* The following loop attempts to maximize the number of times we
2380 pop the top of the stack, as this permits the use of the faster
2381 ffreep instruction on platforms that support it. */
2385 for (reg = 0; reg <= old->top; reg++)
2386 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2390 while (old->top >= live)
2391 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[old->top]))
2393 while (TEST_HARD_REG_BIT (new->reg_set, old->reg[next]))
2395 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[next], DFmode),
2399 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[old->top], DFmode),
2405 /* If the new block has never been processed, then it can inherit
2406 the old stack order. */
2408 new->top = old->top;
2409 memcpy (new->reg, old->reg, sizeof (new->reg));
2413 /* This block has been entered before, and we must match the
2414 previously selected stack order. */
2416 /* By now, the only difference should be the order of the stack,
2417 not their depth or liveliness. */
2419 GO_IF_HARD_REG_EQUAL (old->reg_set, new->reg_set, win);
2422 gcc_assert (old->top == new->top);
2424 /* If the stack is not empty (new->top != -1), loop here emitting
2425 swaps until the stack is correct.
2427 The worst case number of swaps emitted is N + 2, where N is the
2428 depth of the stack. In some cases, the reg at the top of
2429 stack may be correct, but swapped anyway in order to fix
2430 other regs. But since we never swap any other reg away from
2431 its correct slot, this algorithm will converge. */
2436 /* Swap the reg at top of stack into the position it is
2437 supposed to be in, until the correct top of stack appears. */
2439 while (old->reg[old->top] != new->reg[new->top])
2441 for (reg = new->top; reg >= 0; reg--)
2442 if (new->reg[reg] == old->reg[old->top])
2445 gcc_assert (reg != -1);
2447 emit_swap_insn (insn, old,
2448 FP_MODE_REG (old->reg[reg], DFmode));
2451 /* See if any regs remain incorrect. If so, bring an
2452 incorrect reg to the top of stack, and let the while loop
2455 for (reg = new->top; reg >= 0; reg--)
2456 if (new->reg[reg] != old->reg[reg])
2458 emit_swap_insn (insn, old,
2459 FP_MODE_REG (old->reg[reg], DFmode));
2464 /* At this point there must be no differences. */
2466 for (reg = old->top; reg >= 0; reg--)
2467 gcc_assert (old->reg[reg] == new->reg[reg]);
2471 BB_END (current_block) = PREV_INSN (insn);
2474 /* Print stack configuration. */
2477 print_stack (FILE *file, stack s)
2483 fprintf (file, "uninitialized\n");
2484 else if (s->top == -1)
2485 fprintf (file, "empty\n");
2490 for (i = 0; i <= s->top; ++i)
2491 fprintf (file, "%d ", s->reg[i]);
2492 fputs ("]\n", file);
2496 /* This function was doing life analysis. We now let the regular live
2497 code do it's job, so we only need to check some extra invariants
2498 that reg-stack expects. Primary among these being that all registers
2499 are initialized before use.
2501 The function returns true when code was emitted to CFG edges and
2502 commit_edge_insertions needs to be called. */
2505 convert_regs_entry (void)
2511 /* Load something into each stack register live at function entry.
2512 Such live registers can be caused by uninitialized variables or
2513 functions not returning values on all paths. In order to keep
2514 the push/pop code happy, and to not scrog the register stack, we
2515 must put something in these registers. Use a QNaN.
2517 Note that we are inserting converted code here. This code is
2518 never seen by the convert_regs pass. */
2520 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2522 basic_block block = e->dest;
2523 block_info bi = BLOCK_INFO (block);
2526 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2527 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2531 bi->stack_in.reg[++top] = reg;
2533 init = gen_rtx_SET (VOIDmode,
2534 FP_MODE_REG (FIRST_STACK_REG, SFmode),
2536 insert_insn_on_edge (init, e);
2540 bi->stack_in.top = top;
2546 /* Construct the desired stack for function exit. This will either
2547 be `empty', or the function return value at top-of-stack. */
2550 convert_regs_exit (void)
2552 int value_reg_low, value_reg_high;
2556 retvalue = stack_result (current_function_decl);
2557 value_reg_low = value_reg_high = -1;
2560 value_reg_low = REGNO (retvalue);
2561 value_reg_high = value_reg_low
2562 + hard_regno_nregs[value_reg_low][GET_MODE (retvalue)] - 1;
2565 output_stack = &BLOCK_INFO (EXIT_BLOCK_PTR)->stack_in;
2566 if (value_reg_low == -1)
2567 output_stack->top = -1;
2572 output_stack->top = value_reg_high - value_reg_low;
2573 for (reg = value_reg_low; reg <= value_reg_high; ++reg)
2575 output_stack->reg[value_reg_high - reg] = reg;
2576 SET_HARD_REG_BIT (output_stack->reg_set, reg);
2581 /* If the stack of the target block hasn't been processed yet,
2582 copy the stack info from the source block. */
2585 propagate_stack (edge e)
2587 basic_block dest = e->dest;
2588 stack dest_stack = &BLOCK_INFO (dest)->stack_in;
2590 if (dest_stack->top == -2)
2592 basic_block src = e->src;
2593 stack src_stack = &BLOCK_INFO (src)->stack_out;
2596 /* Preserve the order of the original stack, but check whether
2597 any pops are needed. */
2598 dest_stack->top = -1;
2599 for (reg = 0; reg <= src_stack->top; ++reg)
2600 if (TEST_HARD_REG_BIT (dest_stack->reg_set, src_stack->reg[reg]))
2601 dest_stack->reg[++dest_stack->top] = src_stack->reg[reg];
2606 /* Adjust the stack of edge E's source block on exit to match the stack
2607 of it's target block upon input. The stack layouts of both blocks
2608 should have been defined by now. */
2611 compensate_edge (edge e, FILE *file)
2613 basic_block block = e->src, target = e->dest;
2614 block_info bi = BLOCK_INFO (block);
2615 struct stack_def regstack, tmpstack;
2616 stack target_stack = &BLOCK_INFO (target)->stack_in;
2619 current_block = block;
2620 regstack = bi->stack_out;
2622 fprintf (file, "Edge %d->%d: ", block->index, target->index);
2624 gcc_assert (target_stack->top != -2);
2626 /* Check whether stacks are identical. */
2627 if (target_stack->top == regstack.top)
2629 for (reg = target_stack->top; reg >= 0; --reg)
2630 if (target_stack->reg[reg] != regstack.reg[reg])
2636 fprintf (file, "no changes needed\n");
2643 fprintf (file, "correcting stack to ");
2644 print_stack (file, target_stack);
2647 /* Care for non-call EH edges specially. The normal return path have
2648 values in registers. These will be popped en masse by the unwind
2650 if ((e->flags & (EDGE_EH | EDGE_ABNORMAL_CALL)) == EDGE_EH)
2651 target_stack->top = -1;
2653 /* Other calls may appear to have values live in st(0), but the
2654 abnormal return path will not have actually loaded the values. */
2655 else if (e->flags & EDGE_ABNORMAL_CALL)
2657 /* Assert that the lifetimes are as we expect -- one value
2658 live at st(0) on the end of the source block, and no
2659 values live at the beginning of the destination block. */
2662 CLEAR_HARD_REG_SET (tmp);
2663 GO_IF_HARD_REG_EQUAL (target_stack->reg_set, tmp, eh1);
2667 /* We are sure that there is st(0) live, otherwise we won't compensate.
2668 For complex return values, we may have st(1) live as well. */
2669 SET_HARD_REG_BIT (tmp, FIRST_STACK_REG);
2670 if (TEST_HARD_REG_BIT (regstack.reg_set, FIRST_STACK_REG + 1))
2671 SET_HARD_REG_BIT (tmp, FIRST_STACK_REG + 1);
2672 GO_IF_HARD_REG_EQUAL (regstack.reg_set, tmp, eh2);
2676 target_stack->top = -1;
2679 /* It is better to output directly to the end of the block
2680 instead of to the edge, because emit_swap can do minimal
2681 insn scheduling. We can do this when there is only one
2682 edge out, and it is not abnormal. */
2683 else if (EDGE_COUNT (block->succs) == 1 && !(e->flags & EDGE_ABNORMAL))
2685 /* change_stack kills values in regstack. */
2686 tmpstack = regstack;
2688 change_stack (BB_END (block), &tmpstack, target_stack,
2689 (JUMP_P (BB_END (block))
2690 ? EMIT_BEFORE : EMIT_AFTER));
2696 /* We don't support abnormal edges. Global takes care to
2697 avoid any live register across them, so we should never
2698 have to insert instructions on such edges. */
2699 gcc_assert (!(e->flags & EDGE_ABNORMAL));
2701 current_block = NULL;
2704 /* ??? change_stack needs some point to emit insns after. */
2705 after = emit_note (NOTE_INSN_DELETED);
2707 tmpstack = regstack;
2708 change_stack (after, &tmpstack, target_stack, EMIT_BEFORE);
2713 insert_insn_on_edge (seq, e);
2719 /* Traverse all non-entry edges in the CFG, and emit the necessary
2720 edge compensation code to change the stack from stack_out of the
2721 source block to the stack_in of the destination block. */
2724 compensate_edges (FILE *file)
2726 bool inserted = false;
2730 if (bb != ENTRY_BLOCK_PTR)
2735 FOR_EACH_EDGE (e, ei, bb->succs)
2736 inserted |= compensate_edge (e, file);
2741 /* Convert stack register references in one block. */
2744 convert_regs_1 (FILE *file, basic_block block)
2746 struct stack_def regstack;
2747 block_info bi = BLOCK_INFO (block);
2750 edge e, beste = NULL;
2751 bool control_flow_insn_deleted = false;
2754 any_malformed_asm = false;
2756 /* Find the edge we will copy stack from. It should be the most frequent
2757 one as it will get cheapest after compensation code is generated,
2758 if multiple such exists, take one with largest count, prefer critical
2759 one (as splitting critical edges is more expensive), or one with lowest
2760 index, to avoid random changes with different orders of the edges. */
2761 FOR_EACH_EDGE (e, ei, block->preds)
2763 if (e->flags & EDGE_DFS_BACK)
2767 else if (EDGE_FREQUENCY (beste) < EDGE_FREQUENCY (e))
2769 else if (EDGE_FREQUENCY (beste) > EDGE_FREQUENCY (e))
2771 else if (beste->count < e->count)
2773 else if (beste->count > e->count)
2775 else if ((EDGE_CRITICAL_P (e) != 0)
2776 != (EDGE_CRITICAL_P (beste) != 0))
2778 if (EDGE_CRITICAL_P (e))
2781 else if (e->src->index < beste->src->index)
2785 /* Initialize stack at block entry. */
2786 if (bi->stack_in.top == -2)
2789 propagate_stack (beste);
2792 /* No predecessors. Create an arbitrary input stack. */
2795 bi->stack_in.top = -1;
2796 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2797 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2798 bi->stack_in.reg[++bi->stack_in.top] = reg;
2802 /* Entry blocks do have stack already initialized. */
2805 current_block = block;
2809 fprintf (file, "\nBasic block %d\nInput stack: ", block->index);
2810 print_stack (file, &bi->stack_in);
2813 /* Process all insns in this block. Keep track of NEXT so that we
2814 don't process insns emitted while substituting in INSN. */
2815 next = BB_HEAD (block);
2816 regstack = bi->stack_in;
2820 next = NEXT_INSN (insn);
2822 /* Ensure we have not missed a block boundary. */
2824 if (insn == BB_END (block))
2827 /* Don't bother processing unless there is a stack reg
2828 mentioned or if it's a CALL_INSN. */
2829 if (stack_regs_mentioned (insn)
2834 fprintf (file, " insn %d input stack: ",
2836 print_stack (file, ®stack);
2838 control_flow_insn_deleted |= subst_stack_regs (insn, ®stack);
2845 fprintf (file, "Expected live registers [");
2846 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2847 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg))
2848 fprintf (file, " %d", reg);
2849 fprintf (file, " ]\nOutput stack: ");
2850 print_stack (file, ®stack);
2853 insn = BB_END (block);
2855 insn = PREV_INSN (insn);
2857 /* If the function is declared to return a value, but it returns one
2858 in only some cases, some registers might come live here. Emit
2859 necessary moves for them. */
2861 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2863 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg)
2864 && ! TEST_HARD_REG_BIT (regstack.reg_set, reg))
2869 fprintf (file, "Emitting insn initializing reg %d\n", reg);
2871 set = gen_rtx_SET (VOIDmode, FP_MODE_REG (reg, SFmode), not_a_num);
2872 insn = emit_insn_after (set, insn);
2873 control_flow_insn_deleted |= subst_stack_regs (insn, ®stack);
2877 /* Amongst the insns possibly deleted during the substitution process above,
2878 might have been the only trapping insn in the block. We purge the now
2879 possibly dead EH edges here to avoid an ICE from fixup_abnormal_edges,
2880 called at the end of convert_regs. The order in which we process the
2881 blocks ensures that we never delete an already processed edge.
2883 Note that, at this point, the CFG may have been damaged by the emission
2884 of instructions after an abnormal call, which moves the basic block end
2885 (and is the reason why we call fixup_abnormal_edges later). So we must
2886 be sure that the trapping insn has been deleted before trying to purge
2887 dead edges, otherwise we risk purging valid edges.
2889 ??? We are normally supposed not to delete trapping insns, so we pretend
2890 that the insns deleted above don't actually trap. It would have been
2891 better to detect this earlier and avoid creating the EH edge in the first
2892 place, still, but we don't have enough information at that time. */
2894 if (control_flow_insn_deleted)
2895 purge_dead_edges (block);
2897 /* Something failed if the stack lives don't match. If we had malformed
2898 asms, we zapped the instruction itself, but that didn't produce the
2899 same pattern of register kills as before. */
2900 GO_IF_HARD_REG_EQUAL (regstack.reg_set, bi->out_reg_set, win);
2901 gcc_assert (any_malformed_asm);
2903 bi->stack_out = regstack;
2905 /* Compensate the back edges, as those wasn't visited yet. */
2906 FOR_EACH_EDGE (e, ei, block->succs)
2908 if (e->flags & EDGE_DFS_BACK
2909 || (e->dest == EXIT_BLOCK_PTR))
2911 gcc_assert (BLOCK_INFO (e->dest)->done
2912 || e->dest == block);
2913 propagate_stack (e);
2917 FOR_EACH_EDGE (e, ei, block->preds)
2919 if (e != beste && !(e->flags & EDGE_DFS_BACK)
2920 && e->src != ENTRY_BLOCK_PTR)
2922 gcc_assert (BLOCK_INFO (e->src)->done);
2923 propagate_stack (e);
2928 /* Convert registers in all blocks reachable from BLOCK. */
2931 convert_regs_2 (FILE *file, basic_block block)
2933 basic_block *stack, *sp;
2935 /* We process the blocks in a top-down manner, in a way such that one block
2936 is only processed after all its predecessors. The number of predecessors
2937 of every block has already been computed. */
2939 stack = xmalloc (sizeof (*stack) * n_basic_blocks);
2951 /* Processing BLOCK is achieved by convert_regs_1, which may purge
2952 some dead EH outgoing edge after the deletion of the trapping
2953 insn inside the block. Since the number of predecessors of
2954 BLOCK's successors was computed based on the initial edge set,
2955 we check the necessity to process some of these successors
2956 before such an edge deletion may happen. However, there is
2957 a pitfall: if BLOCK is the only predecessor of a successor and
2958 the edge between them happens to be deleted, the successor
2959 becomes unreachable and should not be processed. The problem
2960 is that there is no way to preventively detect this case so we
2961 stack the successor in all cases and hand over the task of
2962 fixing up the discrepancy to convert_regs_1. */
2964 FOR_EACH_EDGE (e, ei, block->succs)
2965 if (! (e->flags & EDGE_DFS_BACK))
2967 BLOCK_INFO (e->dest)->predecessors--;
2968 if (!BLOCK_INFO (e->dest)->predecessors)
2972 convert_regs_1 (file, block);
2973 BLOCK_INFO (block)->done = 1;
2975 while (sp != stack);
2980 /* Traverse all basic blocks in a function, converting the register
2981 references in each insn from the "flat" register file that gcc uses,
2982 to the stack-like registers the 387 uses. */
2985 convert_regs (FILE *file)
2992 /* Initialize uninitialized registers on function entry. */
2993 inserted = convert_regs_entry ();
2995 /* Construct the desired stack for function exit. */
2996 convert_regs_exit ();
2997 BLOCK_INFO (EXIT_BLOCK_PTR)->done = 1;
2999 /* ??? Future: process inner loops first, and give them arbitrary
3000 initial stacks which emit_swap_insn can modify. This ought to
3001 prevent double fxch that often appears at the head of a loop. */
3003 /* Process all blocks reachable from all entry points. */
3004 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3005 convert_regs_2 (file, e->dest);
3007 /* ??? Process all unreachable blocks. Though there's no excuse
3008 for keeping these even when not optimizing. */
3011 block_info bi = BLOCK_INFO (b);
3014 convert_regs_2 (file, b);
3017 inserted |= compensate_edges (file);
3019 clear_aux_for_blocks ();
3021 fixup_abnormal_edges ();
3023 commit_edge_insertions ();
3029 /* Convert register usage from "flat" register file usage to a "stack
3030 register file. FILE is the dump file, if used.
3032 Construct a CFG and run life analysis. Then convert each insn one
3033 by one. Run a last cleanup_cfg pass, if optimizing, to eliminate
3034 code duplication created when the converter inserts pop insns on
3038 reg_to_stack (FILE *file)
3044 /* Clean up previous run. */
3045 stack_regs_mentioned_data = 0;
3047 /* See if there is something to do. Flow analysis is quite
3048 expensive so we might save some compilation time. */
3049 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
3050 if (regs_ever_live[i])
3052 if (i > LAST_STACK_REG)
3055 /* Ok, floating point instructions exist. If not optimizing,
3056 build the CFG and run life analysis.
3057 Also need to rebuild life when superblock scheduling is done
3058 as it don't update liveness yet. */
3060 || (flag_sched2_use_superblocks
3061 && flag_schedule_insns_after_reload))
3063 count_or_remove_death_notes (NULL, 1);
3064 life_analysis (file, PROP_DEATH_NOTES);
3066 mark_dfs_back_edges ();
3068 /* Set up block info for each basic block. */
3069 alloc_aux_for_blocks (sizeof (struct block_info_def));
3072 block_info bi = BLOCK_INFO (bb);
3077 FOR_EACH_EDGE (e, ei, bb->preds)
3078 if (!(e->flags & EDGE_DFS_BACK)
3079 && e->src != ENTRY_BLOCK_PTR)
3082 /* Set current register status at last instruction `uninitialized'. */
3083 bi->stack_in.top = -2;
3085 /* Copy live_at_end and live_at_start into temporaries. */
3086 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; reg++)
3088 if (REGNO_REG_SET_P (bb->global_live_at_end, reg))
3089 SET_HARD_REG_BIT (bi->out_reg_set, reg);
3090 if (REGNO_REG_SET_P (bb->global_live_at_start, reg))
3091 SET_HARD_REG_BIT (bi->stack_in.reg_set, reg);
3095 /* Create the replacement registers up front. */
3096 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
3098 enum machine_mode mode;
3099 for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT);
3101 mode = GET_MODE_WIDER_MODE (mode))
3102 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
3103 for (mode = GET_CLASS_NARROWEST_MODE (MODE_COMPLEX_FLOAT);
3105 mode = GET_MODE_WIDER_MODE (mode))
3106 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
3109 ix86_flags_rtx = gen_rtx_REG (CCmode, FLAGS_REG);
3111 /* A QNaN for initializing uninitialized variables.
3113 ??? We can't load from constant memory in PIC mode, because
3114 we're inserting these instructions before the prologue and
3115 the PIC register hasn't been set up. In that case, fall back
3116 on zero, which we can get from `ldz'. */
3119 not_a_num = CONST0_RTX (SFmode);
3122 not_a_num = gen_lowpart (SFmode, GEN_INT (0x7fc00000));
3123 not_a_num = force_const_mem (SFmode, not_a_num);
3126 /* Allocate a cache for stack_regs_mentioned. */
3127 max_uid = get_max_uid ();
3128 VARRAY_CHAR_INIT (stack_regs_mentioned_data, max_uid + 1,
3129 "stack_regs_mentioned cache");
3131 convert_regs (file);
3133 free_aux_for_blocks ();
3136 #endif /* STACK_REGS */
3138 #include "gt-reg-stack.h"