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"
180 /* We use this array to cache info about insns, because otherwise we
181 spend too much time in stack_regs_mentioned_p.
183 Indexed by insn UIDs. A value of zero is uninitialized, one indicates
184 the insn uses stack registers, two indicates the insn does not use
186 static VEC(char,heap) *stack_regs_mentioned_data;
188 #define REG_STACK_SIZE (LAST_STACK_REG - FIRST_STACK_REG + 1)
190 int regstack_completed = 0;
192 /* This is the basic stack record. TOP is an index into REG[] such
193 that REG[TOP] is the top of stack. If TOP is -1 the stack is empty.
195 If TOP is -2, REG[] is not yet initialized. Stack initialization
196 consists of placing each live reg in array `reg' and setting `top'
199 REG_SET indicates which registers are live. */
201 typedef struct stack_def
203 int top; /* index to top stack element */
204 HARD_REG_SET reg_set; /* set of live registers */
205 unsigned char reg[REG_STACK_SIZE];/* register - stack mapping */
208 /* This is used to carry information about basic blocks. It is
209 attached to the AUX field of the standard CFG block. */
211 typedef struct block_info_def
213 struct stack_def stack_in; /* Input stack configuration. */
214 struct stack_def stack_out; /* Output stack configuration. */
215 HARD_REG_SET out_reg_set; /* Stack regs live on output. */
216 int done; /* True if block already converted. */
217 int predecessors; /* Number of predecessors that need
221 #define BLOCK_INFO(B) ((block_info) (B)->aux)
223 /* Passed to change_stack to indicate where to emit insns. */
230 /* The block we're currently working on. */
231 static basic_block current_block;
233 /* In the current_block, whether we're processing the first register
234 stack or call instruction, i.e. the regstack is currently the
235 same as BLOCK_INFO(current_block)->stack_in. */
236 static bool starting_stack_p;
238 /* This is the register file for all register after conversion. */
240 FP_mode_reg[LAST_STACK_REG+1-FIRST_STACK_REG][(int) MAX_MACHINE_MODE];
242 #define FP_MODE_REG(regno,mode) \
243 (FP_mode_reg[(regno)-FIRST_STACK_REG][(int) (mode)])
245 /* Used to initialize uninitialized registers. */
246 static rtx not_a_num;
248 /* Forward declarations */
250 static int stack_regs_mentioned_p (rtx pat);
251 static void pop_stack (stack, int);
252 static rtx *get_true_reg (rtx *);
254 static int check_asm_stack_operands (rtx);
255 static int get_asm_operand_n_inputs (rtx);
256 static rtx stack_result (tree);
257 static void replace_reg (rtx *, int);
258 static void remove_regno_note (rtx, enum reg_note, unsigned int);
259 static int get_hard_regnum (stack, rtx);
260 static rtx emit_pop_insn (rtx, stack, rtx, enum emit_where);
261 static void swap_to_top(rtx, stack, rtx, rtx);
262 static bool move_for_stack_reg (rtx, stack, rtx);
263 static bool move_nan_for_stack_reg (rtx, stack, rtx);
264 static int swap_rtx_condition_1 (rtx);
265 static int swap_rtx_condition (rtx);
266 static void compare_for_stack_reg (rtx, stack, rtx);
267 static bool subst_stack_regs_pat (rtx, stack, rtx);
268 static void subst_asm_stack_regs (rtx, stack);
269 static bool subst_stack_regs (rtx, stack);
270 static void change_stack (rtx, stack, stack, enum emit_where);
271 static void print_stack (FILE *, stack);
272 static rtx next_flags_user (rtx);
274 /* Return nonzero if any stack register is mentioned somewhere within PAT. */
277 stack_regs_mentioned_p (rtx pat)
282 if (STACK_REG_P (pat))
285 fmt = GET_RTX_FORMAT (GET_CODE (pat));
286 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
292 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
293 if (stack_regs_mentioned_p (XVECEXP (pat, i, j)))
296 else if (fmt[i] == 'e' && stack_regs_mentioned_p (XEXP (pat, i)))
303 /* Return nonzero if INSN mentions stacked registers, else return zero. */
306 stack_regs_mentioned (rtx insn)
308 unsigned int uid, max;
311 if (! INSN_P (insn) || !stack_regs_mentioned_data)
314 uid = INSN_UID (insn);
315 max = VEC_length (char, stack_regs_mentioned_data);
319 unsigned int old_max = max;
321 /* Allocate some extra size to avoid too many reallocs, but
322 do not grow too quickly. */
323 max = uid + uid / 20 + 1;
324 VEC_safe_grow (char, heap, stack_regs_mentioned_data, max);
325 p = VEC_address (char, stack_regs_mentioned_data);
326 memset (&p[old_max], 0,
327 sizeof (char) * (max - old_max));
330 test = VEC_index (char, stack_regs_mentioned_data, uid);
333 /* This insn has yet to be examined. Do so now. */
334 test = stack_regs_mentioned_p (PATTERN (insn)) ? 1 : 2;
335 VEC_replace (char, stack_regs_mentioned_data, uid, test);
341 static rtx ix86_flags_rtx;
344 next_flags_user (rtx insn)
346 /* Search forward looking for the first use of this value.
347 Stop at block boundaries. */
349 while (insn != BB_END (current_block))
351 insn = NEXT_INSN (insn);
353 if (INSN_P (insn) && reg_mentioned_p (ix86_flags_rtx, PATTERN (insn)))
362 /* Reorganize the stack into ascending numbers, before this insn. */
365 straighten_stack (rtx insn, stack regstack)
367 struct stack_def temp_stack;
370 /* If there is only a single register on the stack, then the stack is
371 already in increasing order and no reorganization is needed.
373 Similarly if the stack is empty. */
374 if (regstack->top <= 0)
377 COPY_HARD_REG_SET (temp_stack.reg_set, regstack->reg_set);
379 for (top = temp_stack.top = regstack->top; top >= 0; top--)
380 temp_stack.reg[top] = FIRST_STACK_REG + temp_stack.top - top;
382 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
385 /* Pop a register from the stack. */
388 pop_stack (stack regstack, int regno)
390 int top = regstack->top;
392 CLEAR_HARD_REG_BIT (regstack->reg_set, regno);
394 /* If regno was not at the top of stack then adjust stack. */
395 if (regstack->reg [top] != regno)
398 for (i = regstack->top; i >= 0; i--)
399 if (regstack->reg [i] == regno)
402 for (j = i; j < top; j++)
403 regstack->reg [j] = regstack->reg [j + 1];
409 /* Return a pointer to the REG expression within PAT. If PAT is not a
410 REG, possible enclosed by a conversion rtx, return the inner part of
411 PAT that stopped the search. */
414 get_true_reg (rtx *pat)
417 switch (GET_CODE (*pat))
420 /* Eliminate FP subregister accesses in favor of the
421 actual FP register in use. */
424 if (FP_REG_P (subreg = SUBREG_REG (*pat)))
426 int regno_off = subreg_regno_offset (REGNO (subreg),
430 *pat = FP_MODE_REG (REGNO (subreg) + regno_off,
439 pat = & XEXP (*pat, 0);
443 if (!flag_unsafe_math_optimizations)
445 pat = & XEXP (*pat, 0);
450 /* Set if we find any malformed asms in a block. */
451 static bool any_malformed_asm;
453 /* There are many rules that an asm statement for stack-like regs must
454 follow. Those rules are explained at the top of this file: the rule
455 numbers below refer to that explanation. */
458 check_asm_stack_operands (rtx insn)
462 int malformed_asm = 0;
463 rtx body = PATTERN (insn);
465 char reg_used_as_output[FIRST_PSEUDO_REGISTER];
466 char implicitly_dies[FIRST_PSEUDO_REGISTER];
469 rtx *clobber_reg = 0;
470 int n_inputs, n_outputs;
472 /* Find out what the constraints require. If no constraint
473 alternative matches, this asm is malformed. */
475 constrain_operands (1);
476 alt = which_alternative;
478 preprocess_constraints ();
480 n_inputs = get_asm_operand_n_inputs (body);
481 n_outputs = recog_data.n_operands - n_inputs;
486 /* Avoid further trouble with this insn. */
487 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
491 /* Strip SUBREGs here to make the following code simpler. */
492 for (i = 0; i < recog_data.n_operands; i++)
493 if (GET_CODE (recog_data.operand[i]) == SUBREG
494 && REG_P (SUBREG_REG (recog_data.operand[i])))
495 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
497 /* Set up CLOBBER_REG. */
501 if (GET_CODE (body) == PARALLEL)
503 clobber_reg = alloca (XVECLEN (body, 0) * sizeof (rtx));
505 for (i = 0; i < XVECLEN (body, 0); i++)
506 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
508 rtx clobber = XVECEXP (body, 0, i);
509 rtx reg = XEXP (clobber, 0);
511 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
512 reg = SUBREG_REG (reg);
514 if (STACK_REG_P (reg))
516 clobber_reg[n_clobbers] = reg;
522 /* Enforce rule #4: Output operands must specifically indicate which
523 reg an output appears in after an asm. "=f" is not allowed: the
524 operand constraints must select a class with a single reg.
526 Also enforce rule #5: Output operands must start at the top of
527 the reg-stack: output operands may not "skip" a reg. */
529 memset (reg_used_as_output, 0, sizeof (reg_used_as_output));
530 for (i = 0; i < n_outputs; i++)
531 if (STACK_REG_P (recog_data.operand[i]))
533 if (reg_class_size[(int) recog_op_alt[i][alt].cl] != 1)
535 error_for_asm (insn, "output constraint %d must specify a single register", i);
542 for (j = 0; j < n_clobbers; j++)
543 if (REGNO (recog_data.operand[i]) == REGNO (clobber_reg[j]))
545 error_for_asm (insn, "output constraint %d cannot be specified together with \"%s\" clobber",
546 i, reg_names [REGNO (clobber_reg[j])]);
551 reg_used_as_output[REGNO (recog_data.operand[i])] = 1;
556 /* Search for first non-popped reg. */
557 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
558 if (! reg_used_as_output[i])
561 /* If there are any other popped regs, that's an error. */
562 for (; i < LAST_STACK_REG + 1; i++)
563 if (reg_used_as_output[i])
566 if (i != LAST_STACK_REG + 1)
568 error_for_asm (insn, "output regs must be grouped at top of stack");
572 /* Enforce rule #2: All implicitly popped input regs must be closer
573 to the top of the reg-stack than any input that is not implicitly
576 memset (implicitly_dies, 0, sizeof (implicitly_dies));
577 for (i = n_outputs; i < n_outputs + n_inputs; i++)
578 if (STACK_REG_P (recog_data.operand[i]))
580 /* An input reg is implicitly popped if it is tied to an
581 output, or if there is a CLOBBER for it. */
584 for (j = 0; j < n_clobbers; j++)
585 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
588 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
589 implicitly_dies[REGNO (recog_data.operand[i])] = 1;
592 /* Search for first non-popped reg. */
593 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
594 if (! implicitly_dies[i])
597 /* If there are any other popped regs, that's an error. */
598 for (; i < LAST_STACK_REG + 1; i++)
599 if (implicitly_dies[i])
602 if (i != LAST_STACK_REG + 1)
605 "implicitly popped regs must be grouped at top of stack");
609 /* Enforce rule #3: If any input operand uses the "f" constraint, all
610 output constraints must use the "&" earlyclobber.
612 ??? Detect this more deterministically by having constrain_asm_operands
613 record any earlyclobber. */
615 for (i = n_outputs; i < n_outputs + n_inputs; i++)
616 if (recog_op_alt[i][alt].matches == -1)
620 for (j = 0; j < n_outputs; j++)
621 if (operands_match_p (recog_data.operand[j], recog_data.operand[i]))
624 "output operand %d must use %<&%> constraint", j);
631 /* Avoid further trouble with this insn. */
632 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
633 any_malformed_asm = true;
640 /* Calculate the number of inputs and outputs in BODY, an
641 asm_operands. N_OPERANDS is the total number of operands, and
642 N_INPUTS and N_OUTPUTS are pointers to ints into which the results are
646 get_asm_operand_n_inputs (rtx body)
648 switch (GET_CODE (body))
651 gcc_assert (GET_CODE (SET_SRC (body)) == ASM_OPERANDS);
652 return ASM_OPERANDS_INPUT_LENGTH (SET_SRC (body));
655 return ASM_OPERANDS_INPUT_LENGTH (body);
658 return get_asm_operand_n_inputs (XVECEXP (body, 0, 0));
665 /* If current function returns its result in an fp stack register,
666 return the REG. Otherwise, return 0. */
669 stack_result (tree decl)
673 /* If the value is supposed to be returned in memory, then clearly
674 it is not returned in a stack register. */
675 if (aggregate_value_p (DECL_RESULT (decl), decl))
678 result = DECL_RTL_IF_SET (DECL_RESULT (decl));
680 result = targetm.calls.function_value (TREE_TYPE (DECL_RESULT (decl)),
683 return result != 0 && STACK_REG_P (result) ? result : 0;
688 * This section deals with stack register substitution, and forms the second
692 /* Replace REG, which is a pointer to a stack reg RTX, with an RTX for
693 the desired hard REGNO. */
696 replace_reg (rtx *reg, int regno)
698 gcc_assert (regno >= FIRST_STACK_REG);
699 gcc_assert (regno <= LAST_STACK_REG);
700 gcc_assert (STACK_REG_P (*reg));
702 gcc_assert (SCALAR_FLOAT_MODE_P (GET_MODE (*reg))
703 || GET_MODE_CLASS (GET_MODE (*reg)) == MODE_COMPLEX_FLOAT);
705 *reg = FP_MODE_REG (regno, GET_MODE (*reg));
708 /* Remove a note of type NOTE, which must be found, for register
709 number REGNO from INSN. Remove only one such note. */
712 remove_regno_note (rtx insn, enum reg_note note, unsigned int regno)
714 rtx *note_link, this;
716 note_link = ®_NOTES (insn);
717 for (this = *note_link; this; this = XEXP (this, 1))
718 if (REG_NOTE_KIND (this) == note
719 && REG_P (XEXP (this, 0)) && REGNO (XEXP (this, 0)) == regno)
721 *note_link = XEXP (this, 1);
725 note_link = &XEXP (this, 1);
730 /* Find the hard register number of virtual register REG in REGSTACK.
731 The hard register number is relative to the top of the stack. -1 is
732 returned if the register is not found. */
735 get_hard_regnum (stack regstack, rtx reg)
739 gcc_assert (STACK_REG_P (reg));
741 for (i = regstack->top; i >= 0; i--)
742 if (regstack->reg[i] == REGNO (reg))
745 return i >= 0 ? (FIRST_STACK_REG + regstack->top - i) : -1;
748 /* Emit an insn to pop virtual register REG before or after INSN.
749 REGSTACK is the stack state after INSN and is updated to reflect this
750 pop. WHEN is either emit_insn_before or emit_insn_after. A pop insn
751 is represented as a SET whose destination is the register to be popped
752 and source is the top of stack. A death note for the top of stack
753 cases the movdf pattern to pop. */
756 emit_pop_insn (rtx insn, stack regstack, rtx reg, enum emit_where where)
758 rtx pop_insn, pop_rtx;
761 /* For complex types take care to pop both halves. These may survive in
762 CLOBBER and USE expressions. */
763 if (COMPLEX_MODE_P (GET_MODE (reg)))
765 rtx reg1 = FP_MODE_REG (REGNO (reg), DFmode);
766 rtx reg2 = FP_MODE_REG (REGNO (reg) + 1, DFmode);
769 if (get_hard_regnum (regstack, reg1) >= 0)
770 pop_insn = emit_pop_insn (insn, regstack, reg1, where);
771 if (get_hard_regnum (regstack, reg2) >= 0)
772 pop_insn = emit_pop_insn (insn, regstack, reg2, where);
773 gcc_assert (pop_insn);
777 hard_regno = get_hard_regnum (regstack, reg);
779 gcc_assert (hard_regno >= FIRST_STACK_REG);
781 pop_rtx = gen_rtx_SET (VOIDmode, FP_MODE_REG (hard_regno, DFmode),
782 FP_MODE_REG (FIRST_STACK_REG, DFmode));
784 if (where == EMIT_AFTER)
785 pop_insn = emit_insn_after (pop_rtx, insn);
787 pop_insn = emit_insn_before (pop_rtx, insn);
790 = gen_rtx_EXPR_LIST (REG_DEAD, FP_MODE_REG (FIRST_STACK_REG, DFmode),
791 REG_NOTES (pop_insn));
793 regstack->reg[regstack->top - (hard_regno - FIRST_STACK_REG)]
794 = regstack->reg[regstack->top];
796 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (reg));
801 /* Emit an insn before or after INSN to swap virtual register REG with
802 the top of stack. REGSTACK is the stack state before the swap, and
803 is updated to reflect the swap. A swap insn is represented as a
804 PARALLEL of two patterns: each pattern moves one reg to the other.
806 If REG is already at the top of the stack, no insn is emitted. */
809 emit_swap_insn (rtx insn, stack regstack, rtx reg)
813 int tmp, other_reg; /* swap regno temps */
814 rtx i1; /* the stack-reg insn prior to INSN */
815 rtx i1set = NULL_RTX; /* the SET rtx within I1 */
817 hard_regno = get_hard_regnum (regstack, reg);
819 if (hard_regno == FIRST_STACK_REG)
821 if (hard_regno == -1)
823 /* Something failed if the register wasn't on the stack. If we had
824 malformed asms, we zapped the instruction itself, but that didn't
825 produce the same pattern of register sets as before. To prevent
826 further failure, adjust REGSTACK to include REG at TOP. */
827 gcc_assert (any_malformed_asm);
828 regstack->reg[++regstack->top] = REGNO (reg);
831 gcc_assert (hard_regno >= FIRST_STACK_REG);
833 other_reg = regstack->top - (hard_regno - FIRST_STACK_REG);
835 tmp = regstack->reg[other_reg];
836 regstack->reg[other_reg] = regstack->reg[regstack->top];
837 regstack->reg[regstack->top] = tmp;
839 /* Find the previous insn involving stack regs, but don't pass a
842 if (current_block && insn != BB_HEAD (current_block))
844 rtx tmp = PREV_INSN (insn);
845 rtx limit = PREV_INSN (BB_HEAD (current_block));
850 || NOTE_INSN_BASIC_BLOCK_P (tmp)
851 || (NONJUMP_INSN_P (tmp)
852 && stack_regs_mentioned (tmp)))
857 tmp = PREV_INSN (tmp);
862 && (i1set = single_set (i1)) != NULL_RTX)
864 rtx i1src = *get_true_reg (&SET_SRC (i1set));
865 rtx i1dest = *get_true_reg (&SET_DEST (i1set));
867 /* If the previous register stack push was from the reg we are to
868 swap with, omit the swap. */
870 if (REG_P (i1dest) && REGNO (i1dest) == FIRST_STACK_REG
872 && REGNO (i1src) == (unsigned) hard_regno - 1
873 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
876 /* If the previous insn wrote to the reg we are to swap with,
879 if (REG_P (i1dest) && REGNO (i1dest) == (unsigned) hard_regno
880 && REG_P (i1src) && REGNO (i1src) == FIRST_STACK_REG
881 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
885 /* Avoid emitting the swap if this is the first register stack insn
886 of the current_block. Instead update the current_block's stack_in
887 and let compensate edges take care of this for us. */
888 if (current_block && starting_stack_p)
890 BLOCK_INFO (current_block)->stack_in = *regstack;
891 starting_stack_p = false;
895 swap_rtx = gen_swapxf (FP_MODE_REG (hard_regno, XFmode),
896 FP_MODE_REG (FIRST_STACK_REG, XFmode));
899 emit_insn_after (swap_rtx, i1);
900 else if (current_block)
901 emit_insn_before (swap_rtx, BB_HEAD (current_block));
903 emit_insn_before (swap_rtx, insn);
906 /* Emit an insns before INSN to swap virtual register SRC1 with
907 the top of stack and virtual register SRC2 with second stack
908 slot. REGSTACK is the stack state before the swaps, and
909 is updated to reflect the swaps. A swap insn is represented as a
910 PARALLEL of two patterns: each pattern moves one reg to the other.
912 If SRC1 and/or SRC2 are already at the right place, no swap insn
916 swap_to_top (rtx insn, stack regstack, rtx src1, rtx src2)
918 struct stack_def temp_stack;
919 int regno, j, k, temp;
921 temp_stack = *regstack;
923 /* Place operand 1 at the top of stack. */
924 regno = get_hard_regnum (&temp_stack, src1);
925 gcc_assert (regno >= 0);
926 if (regno != FIRST_STACK_REG)
928 k = temp_stack.top - (regno - FIRST_STACK_REG);
931 temp = temp_stack.reg[k];
932 temp_stack.reg[k] = temp_stack.reg[j];
933 temp_stack.reg[j] = temp;
936 /* Place operand 2 next on the stack. */
937 regno = get_hard_regnum (&temp_stack, src2);
938 gcc_assert (regno >= 0);
939 if (regno != FIRST_STACK_REG + 1)
941 k = temp_stack.top - (regno - FIRST_STACK_REG);
942 j = temp_stack.top - 1;
944 temp = temp_stack.reg[k];
945 temp_stack.reg[k] = temp_stack.reg[j];
946 temp_stack.reg[j] = temp;
949 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
952 /* Handle a move to or from a stack register in PAT, which is in INSN.
953 REGSTACK is the current stack. Return whether a control flow insn
954 was deleted in the process. */
957 move_for_stack_reg (rtx insn, stack regstack, rtx pat)
959 rtx *psrc = get_true_reg (&SET_SRC (pat));
960 rtx *pdest = get_true_reg (&SET_DEST (pat));
963 bool control_flow_insn_deleted = false;
965 src = *psrc; dest = *pdest;
967 if (STACK_REG_P (src) && STACK_REG_P (dest))
969 /* Write from one stack reg to another. If SRC dies here, then
970 just change the register mapping and delete the insn. */
972 note = find_regno_note (insn, REG_DEAD, REGNO (src));
977 /* If this is a no-op move, there must not be a REG_DEAD note. */
978 gcc_assert (REGNO (src) != REGNO (dest));
980 for (i = regstack->top; i >= 0; i--)
981 if (regstack->reg[i] == REGNO (src))
984 /* The destination must be dead, or life analysis is borked. */
985 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
987 /* If the source is not live, this is yet another case of
988 uninitialized variables. Load up a NaN instead. */
990 return move_nan_for_stack_reg (insn, regstack, dest);
992 /* It is possible that the dest is unused after this insn.
993 If so, just pop the src. */
995 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
996 emit_pop_insn (insn, regstack, src, EMIT_AFTER);
999 regstack->reg[i] = REGNO (dest);
1000 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1001 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1004 control_flow_insn_deleted |= control_flow_insn_p (insn);
1006 return control_flow_insn_deleted;
1009 /* The source reg does not die. */
1011 /* If this appears to be a no-op move, delete it, or else it
1012 will confuse the machine description output patterns. But if
1013 it is REG_UNUSED, we must pop the reg now, as per-insn processing
1014 for REG_UNUSED will not work for deleted insns. */
1016 if (REGNO (src) == REGNO (dest))
1018 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
1019 emit_pop_insn (insn, regstack, dest, EMIT_AFTER);
1021 control_flow_insn_deleted |= control_flow_insn_p (insn);
1023 return control_flow_insn_deleted;
1026 /* The destination ought to be dead. */
1027 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1029 replace_reg (psrc, get_hard_regnum (regstack, src));
1031 regstack->reg[++regstack->top] = REGNO (dest);
1032 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1033 replace_reg (pdest, FIRST_STACK_REG);
1035 else if (STACK_REG_P (src))
1037 /* Save from a stack reg to MEM, or possibly integer reg. Since
1038 only top of stack may be saved, emit an exchange first if
1041 emit_swap_insn (insn, regstack, src);
1043 note = find_regno_note (insn, REG_DEAD, REGNO (src));
1046 replace_reg (&XEXP (note, 0), FIRST_STACK_REG);
1048 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1050 else if ((GET_MODE (src) == XFmode)
1051 && regstack->top < REG_STACK_SIZE - 1)
1053 /* A 387 cannot write an XFmode value to a MEM without
1054 clobbering the source reg. The output code can handle
1055 this by reading back the value from the MEM.
1056 But it is more efficient to use a temp register if one is
1057 available. Push the source value here if the register
1058 stack is not full, and then write the value to memory via
1061 rtx top_stack_reg = FP_MODE_REG (FIRST_STACK_REG, GET_MODE (src));
1063 push_rtx = gen_movxf (top_stack_reg, top_stack_reg);
1064 emit_insn_before (push_rtx, insn);
1065 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_DEAD, top_stack_reg,
1069 replace_reg (psrc, FIRST_STACK_REG);
1073 gcc_assert (STACK_REG_P (dest));
1075 /* Load from MEM, or possibly integer REG or constant, into the
1076 stack regs. The actual target is always the top of the
1077 stack. The stack mapping is changed to reflect that DEST is
1078 now at top of stack. */
1080 /* The destination ought to be dead. */
1081 gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1083 gcc_assert (regstack->top < REG_STACK_SIZE);
1085 regstack->reg[++regstack->top] = REGNO (dest);
1086 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1087 replace_reg (pdest, FIRST_STACK_REG);
1090 return control_flow_insn_deleted;
1093 /* A helper function which replaces INSN with a pattern that loads up
1094 a NaN into DEST, then invokes move_for_stack_reg. */
1097 move_nan_for_stack_reg (rtx insn, stack regstack, rtx dest)
1101 dest = FP_MODE_REG (REGNO (dest), SFmode);
1102 pat = gen_rtx_SET (VOIDmode, dest, not_a_num);
1103 PATTERN (insn) = pat;
1104 INSN_CODE (insn) = -1;
1106 return move_for_stack_reg (insn, regstack, pat);
1109 /* Swap the condition on a branch, if there is one. Return true if we
1110 found a condition to swap. False if the condition was not used as
1114 swap_rtx_condition_1 (rtx pat)
1119 if (COMPARISON_P (pat))
1121 PUT_CODE (pat, swap_condition (GET_CODE (pat)));
1126 fmt = GET_RTX_FORMAT (GET_CODE (pat));
1127 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
1133 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
1134 r |= swap_rtx_condition_1 (XVECEXP (pat, i, j));
1136 else if (fmt[i] == 'e')
1137 r |= swap_rtx_condition_1 (XEXP (pat, i));
1145 swap_rtx_condition (rtx insn)
1147 rtx pat = PATTERN (insn);
1149 /* We're looking for a single set to cc0 or an HImode temporary. */
1151 if (GET_CODE (pat) == SET
1152 && REG_P (SET_DEST (pat))
1153 && REGNO (SET_DEST (pat)) == FLAGS_REG)
1155 insn = next_flags_user (insn);
1156 if (insn == NULL_RTX)
1158 pat = PATTERN (insn);
1161 /* See if this is, or ends in, a fnstsw. If so, we're not doing anything
1162 with the cc value right now. We may be able to search for one
1165 if (GET_CODE (pat) == SET
1166 && GET_CODE (SET_SRC (pat)) == UNSPEC
1167 && XINT (SET_SRC (pat), 1) == UNSPEC_FNSTSW)
1169 rtx dest = SET_DEST (pat);
1171 /* Search forward looking for the first use of this value.
1172 Stop at block boundaries. */
1173 while (insn != BB_END (current_block))
1175 insn = NEXT_INSN (insn);
1176 if (INSN_P (insn) && reg_mentioned_p (dest, insn))
1182 /* We haven't found it. */
1183 if (insn == BB_END (current_block))
1186 /* So we've found the insn using this value. If it is anything
1187 other than sahf or the value does not die (meaning we'd have
1188 to search further), then we must give up. */
1189 pat = PATTERN (insn);
1190 if (GET_CODE (pat) != SET
1191 || GET_CODE (SET_SRC (pat)) != UNSPEC
1192 || XINT (SET_SRC (pat), 1) != UNSPEC_SAHF
1193 || ! dead_or_set_p (insn, dest))
1196 /* Now we are prepared to handle this as a normal cc0 setter. */
1197 insn = next_flags_user (insn);
1198 if (insn == NULL_RTX)
1200 pat = PATTERN (insn);
1203 if (swap_rtx_condition_1 (pat))
1206 INSN_CODE (insn) = -1;
1207 if (recog_memoized (insn) == -1)
1209 /* In case the flags don't die here, recurse to try fix
1210 following user too. */
1211 else if (! dead_or_set_p (insn, ix86_flags_rtx))
1213 insn = next_flags_user (insn);
1214 if (!insn || !swap_rtx_condition (insn))
1219 swap_rtx_condition_1 (pat);
1227 /* Handle a comparison. Special care needs to be taken to avoid
1228 causing comparisons that a 387 cannot do correctly, such as EQ.
1230 Also, a pop insn may need to be emitted. The 387 does have an
1231 `fcompp' insn that can pop two regs, but it is sometimes too expensive
1232 to do this - a `fcomp' followed by a `fstpl %st(0)' may be easier to
1236 compare_for_stack_reg (rtx insn, stack regstack, rtx pat_src)
1239 rtx src1_note, src2_note;
1241 src1 = get_true_reg (&XEXP (pat_src, 0));
1242 src2 = get_true_reg (&XEXP (pat_src, 1));
1244 /* ??? If fxch turns out to be cheaper than fstp, give priority to
1245 registers that die in this insn - move those to stack top first. */
1246 if ((! STACK_REG_P (*src1)
1247 || (STACK_REG_P (*src2)
1248 && get_hard_regnum (regstack, *src2) == FIRST_STACK_REG))
1249 && swap_rtx_condition (insn))
1252 temp = XEXP (pat_src, 0);
1253 XEXP (pat_src, 0) = XEXP (pat_src, 1);
1254 XEXP (pat_src, 1) = temp;
1256 src1 = get_true_reg (&XEXP (pat_src, 0));
1257 src2 = get_true_reg (&XEXP (pat_src, 1));
1259 INSN_CODE (insn) = -1;
1262 /* We will fix any death note later. */
1264 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1266 if (STACK_REG_P (*src2))
1267 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1269 src2_note = NULL_RTX;
1271 emit_swap_insn (insn, regstack, *src1);
1273 replace_reg (src1, FIRST_STACK_REG);
1275 if (STACK_REG_P (*src2))
1276 replace_reg (src2, get_hard_regnum (regstack, *src2));
1280 pop_stack (regstack, REGNO (XEXP (src1_note, 0)));
1281 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1284 /* If the second operand dies, handle that. But if the operands are
1285 the same stack register, don't bother, because only one death is
1286 needed, and it was just handled. */
1289 && ! (STACK_REG_P (*src1) && STACK_REG_P (*src2)
1290 && REGNO (*src1) == REGNO (*src2)))
1292 /* As a special case, two regs may die in this insn if src2 is
1293 next to top of stack and the top of stack also dies. Since
1294 we have already popped src1, "next to top of stack" is really
1295 at top (FIRST_STACK_REG) now. */
1297 if (get_hard_regnum (regstack, XEXP (src2_note, 0)) == FIRST_STACK_REG
1300 pop_stack (regstack, REGNO (XEXP (src2_note, 0)));
1301 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1305 /* The 386 can only represent death of the first operand in
1306 the case handled above. In all other cases, emit a separate
1307 pop and remove the death note from here. */
1309 /* link_cc0_insns (insn); */
1311 remove_regno_note (insn, REG_DEAD, REGNO (XEXP (src2_note, 0)));
1313 emit_pop_insn (insn, regstack, XEXP (src2_note, 0),
1319 /* Substitute new registers in PAT, which is part of INSN. REGSTACK
1320 is the current register layout. Return whether a control flow insn
1321 was deleted in the process. */
1324 subst_stack_regs_pat (rtx insn, stack regstack, rtx pat)
1327 bool control_flow_insn_deleted = false;
1329 switch (GET_CODE (pat))
1332 /* Deaths in USE insns can happen in non optimizing compilation.
1333 Handle them by popping the dying register. */
1334 src = get_true_reg (&XEXP (pat, 0));
1335 if (STACK_REG_P (*src)
1336 && find_regno_note (insn, REG_DEAD, REGNO (*src)))
1338 emit_pop_insn (insn, regstack, *src, EMIT_AFTER);
1339 return control_flow_insn_deleted;
1341 /* ??? Uninitialized USE should not happen. */
1343 gcc_assert (get_hard_regnum (regstack, *src) != -1);
1350 dest = get_true_reg (&XEXP (pat, 0));
1351 if (STACK_REG_P (*dest))
1353 note = find_reg_note (insn, REG_DEAD, *dest);
1355 if (pat != PATTERN (insn))
1357 /* The fix_truncdi_1 pattern wants to be able to allocate
1358 its own scratch register. It does this by clobbering
1359 an fp reg so that it is assured of an empty reg-stack
1360 register. If the register is live, kill it now.
1361 Remove the DEAD/UNUSED note so we don't try to kill it
1365 emit_pop_insn (insn, regstack, *dest, EMIT_BEFORE);
1368 note = find_reg_note (insn, REG_UNUSED, *dest);
1371 remove_note (insn, note);
1372 replace_reg (dest, FIRST_STACK_REG + 1);
1376 /* A top-level clobber with no REG_DEAD, and no hard-regnum
1377 indicates an uninitialized value. Because reload removed
1378 all other clobbers, this must be due to a function
1379 returning without a value. Load up a NaN. */
1384 if (COMPLEX_MODE_P (GET_MODE (t)))
1386 rtx u = FP_MODE_REG (REGNO (t) + 1, SFmode);
1387 if (get_hard_regnum (regstack, u) == -1)
1389 rtx pat2 = gen_rtx_CLOBBER (VOIDmode, u);
1390 rtx insn2 = emit_insn_before (pat2, insn);
1391 control_flow_insn_deleted
1392 |= move_nan_for_stack_reg (insn2, regstack, u);
1395 if (get_hard_regnum (regstack, t) == -1)
1396 control_flow_insn_deleted
1397 |= move_nan_for_stack_reg (insn, regstack, t);
1406 rtx *src1 = (rtx *) 0, *src2;
1407 rtx src1_note, src2_note;
1410 dest = get_true_reg (&SET_DEST (pat));
1411 src = get_true_reg (&SET_SRC (pat));
1412 pat_src = SET_SRC (pat);
1414 /* See if this is a `movM' pattern, and handle elsewhere if so. */
1415 if (STACK_REG_P (*src)
1416 || (STACK_REG_P (*dest)
1417 && (REG_P (*src) || MEM_P (*src)
1418 || GET_CODE (*src) == CONST_DOUBLE)))
1420 control_flow_insn_deleted |= move_for_stack_reg (insn, regstack, pat);
1424 switch (GET_CODE (pat_src))
1427 compare_for_stack_reg (insn, regstack, pat_src);
1433 for (count = hard_regno_nregs[REGNO (*dest)][GET_MODE (*dest)];
1436 regstack->reg[++regstack->top] = REGNO (*dest) + count;
1437 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest) + count);
1440 replace_reg (dest, FIRST_STACK_REG);
1444 /* This is a `tstM2' case. */
1445 gcc_assert (*dest == cc0_rtx);
1450 case FLOAT_TRUNCATE:
1454 /* These insns only operate on the top of the stack. DEST might
1455 be cc0_rtx if we're processing a tstM pattern. Also, it's
1456 possible that the tstM case results in a REG_DEAD note on the
1460 src1 = get_true_reg (&XEXP (pat_src, 0));
1462 emit_swap_insn (insn, regstack, *src1);
1464 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1466 if (STACK_REG_P (*dest))
1467 replace_reg (dest, FIRST_STACK_REG);
1471 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1473 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1476 replace_reg (src1, FIRST_STACK_REG);
1481 /* On i386, reversed forms of subM3 and divM3 exist for
1482 MODE_FLOAT, so the same code that works for addM3 and mulM3
1486 /* These insns can accept the top of stack as a destination
1487 from a stack reg or mem, or can use the top of stack as a
1488 source and some other stack register (possibly top of stack)
1489 as a destination. */
1491 src1 = get_true_reg (&XEXP (pat_src, 0));
1492 src2 = get_true_reg (&XEXP (pat_src, 1));
1494 /* We will fix any death note later. */
1496 if (STACK_REG_P (*src1))
1497 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1499 src1_note = NULL_RTX;
1500 if (STACK_REG_P (*src2))
1501 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1503 src2_note = NULL_RTX;
1505 /* If either operand is not a stack register, then the dest
1506 must be top of stack. */
1508 if (! STACK_REG_P (*src1) || ! STACK_REG_P (*src2))
1509 emit_swap_insn (insn, regstack, *dest);
1512 /* Both operands are REG. If neither operand is already
1513 at the top of stack, choose to make the one that is the dest
1514 the new top of stack. */
1516 int src1_hard_regnum, src2_hard_regnum;
1518 src1_hard_regnum = get_hard_regnum (regstack, *src1);
1519 src2_hard_regnum = get_hard_regnum (regstack, *src2);
1520 gcc_assert (src1_hard_regnum != -1);
1521 gcc_assert (src2_hard_regnum != -1);
1523 if (src1_hard_regnum != FIRST_STACK_REG
1524 && src2_hard_regnum != FIRST_STACK_REG)
1525 emit_swap_insn (insn, regstack, *dest);
1528 if (STACK_REG_P (*src1))
1529 replace_reg (src1, get_hard_regnum (regstack, *src1));
1530 if (STACK_REG_P (*src2))
1531 replace_reg (src2, get_hard_regnum (regstack, *src2));
1535 rtx src1_reg = XEXP (src1_note, 0);
1537 /* If the register that dies is at the top of stack, then
1538 the destination is somewhere else - merely substitute it.
1539 But if the reg that dies is not at top of stack, then
1540 move the top of stack to the dead reg, as though we had
1541 done the insn and then a store-with-pop. */
1543 if (REGNO (src1_reg) == regstack->reg[regstack->top])
1545 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1546 replace_reg (dest, get_hard_regnum (regstack, *dest));
1550 int regno = get_hard_regnum (regstack, src1_reg);
1552 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1553 replace_reg (dest, regno);
1555 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1556 = regstack->reg[regstack->top];
1559 CLEAR_HARD_REG_BIT (regstack->reg_set,
1560 REGNO (XEXP (src1_note, 0)));
1561 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1566 rtx src2_reg = XEXP (src2_note, 0);
1567 if (REGNO (src2_reg) == regstack->reg[regstack->top])
1569 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1570 replace_reg (dest, get_hard_regnum (regstack, *dest));
1574 int regno = get_hard_regnum (regstack, src2_reg);
1576 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1577 replace_reg (dest, regno);
1579 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1580 = regstack->reg[regstack->top];
1583 CLEAR_HARD_REG_BIT (regstack->reg_set,
1584 REGNO (XEXP (src2_note, 0)));
1585 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG);
1590 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1591 replace_reg (dest, get_hard_regnum (regstack, *dest));
1594 /* Keep operand 1 matching with destination. */
1595 if (COMMUTATIVE_ARITH_P (pat_src)
1596 && REG_P (*src1) && REG_P (*src2)
1597 && REGNO (*src1) != REGNO (*dest))
1599 int tmp = REGNO (*src1);
1600 replace_reg (src1, REGNO (*src2));
1601 replace_reg (src2, tmp);
1606 switch (XINT (pat_src, 1))
1610 case UNSPEC_FIST_FLOOR:
1611 case UNSPEC_FIST_CEIL:
1613 /* These insns only operate on the top of the stack. */
1615 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1616 emit_swap_insn (insn, regstack, *src1);
1618 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1620 if (STACK_REG_P (*dest))
1621 replace_reg (dest, FIRST_STACK_REG);
1625 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1627 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1630 replace_reg (src1, FIRST_STACK_REG);
1635 case UNSPEC_FRNDINT:
1638 case UNSPEC_FRNDINT_FLOOR:
1639 case UNSPEC_FRNDINT_CEIL:
1640 case UNSPEC_FRNDINT_TRUNC:
1641 case UNSPEC_FRNDINT_MASK_PM:
1643 /* These insns only operate on the top of the stack. */
1645 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1647 emit_swap_insn (insn, regstack, *src1);
1649 /* Input should never die, it is
1650 replaced with output. */
1651 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1652 gcc_assert (!src1_note);
1654 if (STACK_REG_P (*dest))
1655 replace_reg (dest, FIRST_STACK_REG);
1657 replace_reg (src1, FIRST_STACK_REG);
1662 case UNSPEC_FYL2XP1:
1663 /* These insns operate on the top two stack slots. */
1665 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1666 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1668 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1669 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1671 swap_to_top (insn, regstack, *src1, *src2);
1673 replace_reg (src1, FIRST_STACK_REG);
1674 replace_reg (src2, FIRST_STACK_REG + 1);
1677 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1679 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1681 /* Pop both input operands from the stack. */
1682 CLEAR_HARD_REG_BIT (regstack->reg_set,
1683 regstack->reg[regstack->top]);
1684 CLEAR_HARD_REG_BIT (regstack->reg_set,
1685 regstack->reg[regstack->top - 1]);
1688 /* Push the result back onto the stack. */
1689 regstack->reg[++regstack->top] = REGNO (*dest);
1690 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1691 replace_reg (dest, FIRST_STACK_REG);
1694 case UNSPEC_FSCALE_FRACT:
1695 case UNSPEC_FPREM_F:
1696 case UNSPEC_FPREM1_F:
1697 /* These insns operate on the top two stack slots.
1698 first part of double input, double output insn. */
1700 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1701 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1703 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1704 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1706 /* Inputs should never die, they are
1707 replaced with outputs. */
1708 gcc_assert (!src1_note);
1709 gcc_assert (!src2_note);
1711 swap_to_top (insn, regstack, *src1, *src2);
1713 /* Push the result back onto stack. Empty stack slot
1714 will be filled in second part of insn. */
1715 if (STACK_REG_P (*dest)) {
1716 regstack->reg[regstack->top] = REGNO (*dest);
1717 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1718 replace_reg (dest, FIRST_STACK_REG);
1721 replace_reg (src1, FIRST_STACK_REG);
1722 replace_reg (src2, FIRST_STACK_REG + 1);
1725 case UNSPEC_FSCALE_EXP:
1726 case UNSPEC_FPREM_U:
1727 case UNSPEC_FPREM1_U:
1728 /* These insns operate on the top two stack slots./
1729 second part of double input, double output insn. */
1731 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1732 src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1734 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1735 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1737 /* Inputs should never die, they are
1738 replaced with outputs. */
1739 gcc_assert (!src1_note);
1740 gcc_assert (!src2_note);
1742 swap_to_top (insn, regstack, *src1, *src2);
1744 /* Push the result back onto stack. Fill empty slot from
1745 first part of insn and fix top of stack pointer. */
1746 if (STACK_REG_P (*dest)) {
1747 regstack->reg[regstack->top - 1] = REGNO (*dest);
1748 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1749 replace_reg (dest, FIRST_STACK_REG + 1);
1752 replace_reg (src1, FIRST_STACK_REG);
1753 replace_reg (src2, FIRST_STACK_REG + 1);
1756 case UNSPEC_SINCOS_COS:
1757 case UNSPEC_TAN_ONE:
1758 case UNSPEC_XTRACT_FRACT:
1759 /* These insns operate on the top two stack slots,
1760 first part of one input, double output insn. */
1762 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1764 emit_swap_insn (insn, regstack, *src1);
1766 /* Input should never die, it is
1767 replaced with output. */
1768 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1769 gcc_assert (!src1_note);
1771 /* Push the result back onto stack. Empty stack slot
1772 will be filled in second part of insn. */
1773 if (STACK_REG_P (*dest)) {
1774 regstack->reg[regstack->top + 1] = REGNO (*dest);
1775 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1776 replace_reg (dest, FIRST_STACK_REG);
1779 replace_reg (src1, FIRST_STACK_REG);
1782 case UNSPEC_SINCOS_SIN:
1783 case UNSPEC_TAN_TAN:
1784 case UNSPEC_XTRACT_EXP:
1785 /* These insns operate on the top two stack slots,
1786 second part of one input, double output insn. */
1788 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1790 emit_swap_insn (insn, regstack, *src1);
1792 /* Input should never die, it is
1793 replaced with output. */
1794 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1795 gcc_assert (!src1_note);
1797 /* Push the result back onto stack. Fill empty slot from
1798 first part of insn and fix top of stack pointer. */
1799 if (STACK_REG_P (*dest)) {
1800 regstack->reg[regstack->top] = REGNO (*dest);
1801 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1802 replace_reg (dest, FIRST_STACK_REG + 1);
1807 replace_reg (src1, FIRST_STACK_REG);
1811 /* (unspec [(unspec [(compare)] UNSPEC_FNSTSW)] UNSPEC_SAHF)
1812 The combination matches the PPRO fcomi instruction. */
1814 pat_src = XVECEXP (pat_src, 0, 0);
1815 gcc_assert (GET_CODE (pat_src) == UNSPEC);
1816 gcc_assert (XINT (pat_src, 1) == UNSPEC_FNSTSW);
1820 /* Combined fcomp+fnstsw generated for doing well with
1821 CSE. When optimizing this would have been broken
1824 pat_src = XVECEXP (pat_src, 0, 0);
1825 gcc_assert (GET_CODE (pat_src) == COMPARE);
1827 compare_for_stack_reg (insn, regstack, pat_src);
1836 /* This insn requires the top of stack to be the destination. */
1838 src1 = get_true_reg (&XEXP (pat_src, 1));
1839 src2 = get_true_reg (&XEXP (pat_src, 2));
1841 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1842 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1844 /* If the comparison operator is an FP comparison operator,
1845 it is handled correctly by compare_for_stack_reg () who
1846 will move the destination to the top of stack. But if the
1847 comparison operator is not an FP comparison operator, we
1848 have to handle it here. */
1849 if (get_hard_regnum (regstack, *dest) >= FIRST_STACK_REG
1850 && REGNO (*dest) != regstack->reg[regstack->top])
1852 /* In case one of operands is the top of stack and the operands
1853 dies, it is safe to make it the destination operand by
1854 reversing the direction of cmove and avoid fxch. */
1855 if ((REGNO (*src1) == regstack->reg[regstack->top]
1857 || (REGNO (*src2) == regstack->reg[regstack->top]
1860 int idx1 = (get_hard_regnum (regstack, *src1)
1862 int idx2 = (get_hard_regnum (regstack, *src2)
1865 /* Make reg-stack believe that the operands are already
1866 swapped on the stack */
1867 regstack->reg[regstack->top - idx1] = REGNO (*src2);
1868 regstack->reg[regstack->top - idx2] = REGNO (*src1);
1870 /* Reverse condition to compensate the operand swap.
1871 i386 do have comparison always reversible. */
1872 PUT_CODE (XEXP (pat_src, 0),
1873 reversed_comparison_code (XEXP (pat_src, 0), insn));
1876 emit_swap_insn (insn, regstack, *dest);
1884 src_note[1] = src1_note;
1885 src_note[2] = src2_note;
1887 if (STACK_REG_P (*src1))
1888 replace_reg (src1, get_hard_regnum (regstack, *src1));
1889 if (STACK_REG_P (*src2))
1890 replace_reg (src2, get_hard_regnum (regstack, *src2));
1892 for (i = 1; i <= 2; i++)
1895 int regno = REGNO (XEXP (src_note[i], 0));
1897 /* If the register that dies is not at the top of
1898 stack, then move the top of stack to the dead reg.
1899 Top of stack should never die, as it is the
1901 gcc_assert (regno != regstack->reg[regstack->top]);
1902 remove_regno_note (insn, REG_DEAD, regno);
1903 emit_pop_insn (insn, regstack, XEXP (src_note[i], 0),
1908 /* Make dest the top of stack. Add dest to regstack if
1910 if (get_hard_regnum (regstack, *dest) < FIRST_STACK_REG)
1911 regstack->reg[++regstack->top] = REGNO (*dest);
1912 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1913 replace_reg (dest, FIRST_STACK_REG);
1926 return control_flow_insn_deleted;
1929 /* Substitute hard regnums for any stack regs in INSN, which has
1930 N_INPUTS inputs and N_OUTPUTS outputs. REGSTACK is the stack info
1931 before the insn, and is updated with changes made here.
1933 There are several requirements and assumptions about the use of
1934 stack-like regs in asm statements. These rules are enforced by
1935 record_asm_stack_regs; see comments there for details. Any
1936 asm_operands left in the RTL at this point may be assume to meet the
1937 requirements, since record_asm_stack_regs removes any problem asm. */
1940 subst_asm_stack_regs (rtx insn, stack regstack)
1942 rtx body = PATTERN (insn);
1945 rtx *note_reg; /* Array of note contents */
1946 rtx **note_loc; /* Address of REG field of each note */
1947 enum reg_note *note_kind; /* The type of each note */
1949 rtx *clobber_reg = 0;
1950 rtx **clobber_loc = 0;
1952 struct stack_def temp_stack;
1957 int n_inputs, n_outputs;
1959 if (! check_asm_stack_operands (insn))
1962 /* Find out what the constraints required. If no constraint
1963 alternative matches, that is a compiler bug: we should have caught
1964 such an insn in check_asm_stack_operands. */
1965 extract_insn (insn);
1966 constrain_operands (1);
1967 alt = which_alternative;
1969 preprocess_constraints ();
1971 n_inputs = get_asm_operand_n_inputs (body);
1972 n_outputs = recog_data.n_operands - n_inputs;
1974 gcc_assert (alt >= 0);
1976 /* Strip SUBREGs here to make the following code simpler. */
1977 for (i = 0; i < recog_data.n_operands; i++)
1978 if (GET_CODE (recog_data.operand[i]) == SUBREG
1979 && REG_P (SUBREG_REG (recog_data.operand[i])))
1981 recog_data.operand_loc[i] = & SUBREG_REG (recog_data.operand[i]);
1982 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
1985 /* Set up NOTE_REG, NOTE_LOC and NOTE_KIND. */
1987 for (i = 0, note = REG_NOTES (insn); note; note = XEXP (note, 1))
1990 note_reg = alloca (i * sizeof (rtx));
1991 note_loc = alloca (i * sizeof (rtx *));
1992 note_kind = alloca (i * sizeof (enum reg_note));
1995 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
1997 rtx reg = XEXP (note, 0);
1998 rtx *loc = & XEXP (note, 0);
2000 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
2002 loc = & SUBREG_REG (reg);
2003 reg = SUBREG_REG (reg);
2006 if (STACK_REG_P (reg)
2007 && (REG_NOTE_KIND (note) == REG_DEAD
2008 || REG_NOTE_KIND (note) == REG_UNUSED))
2010 note_reg[n_notes] = reg;
2011 note_loc[n_notes] = loc;
2012 note_kind[n_notes] = REG_NOTE_KIND (note);
2017 /* Set up CLOBBER_REG and CLOBBER_LOC. */
2021 if (GET_CODE (body) == PARALLEL)
2023 clobber_reg = alloca (XVECLEN (body, 0) * sizeof (rtx));
2024 clobber_loc = alloca (XVECLEN (body, 0) * sizeof (rtx *));
2026 for (i = 0; i < XVECLEN (body, 0); i++)
2027 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
2029 rtx clobber = XVECEXP (body, 0, i);
2030 rtx reg = XEXP (clobber, 0);
2031 rtx *loc = & XEXP (clobber, 0);
2033 if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
2035 loc = & SUBREG_REG (reg);
2036 reg = SUBREG_REG (reg);
2039 if (STACK_REG_P (reg))
2041 clobber_reg[n_clobbers] = reg;
2042 clobber_loc[n_clobbers] = loc;
2048 temp_stack = *regstack;
2050 /* Put the input regs into the desired place in TEMP_STACK. */
2052 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2053 if (STACK_REG_P (recog_data.operand[i])
2054 && reg_class_subset_p (recog_op_alt[i][alt].cl,
2056 && recog_op_alt[i][alt].cl != FLOAT_REGS)
2058 /* If an operand needs to be in a particular reg in
2059 FLOAT_REGS, the constraint was either 't' or 'u'. Since
2060 these constraints are for single register classes, and
2061 reload guaranteed that operand[i] is already in that class,
2062 we can just use REGNO (recog_data.operand[i]) to know which
2063 actual reg this operand needs to be in. */
2065 int regno = get_hard_regnum (&temp_stack, recog_data.operand[i]);
2067 gcc_assert (regno >= 0);
2069 if ((unsigned int) regno != REGNO (recog_data.operand[i]))
2071 /* recog_data.operand[i] is not in the right place. Find
2072 it and swap it with whatever is already in I's place.
2073 K is where recog_data.operand[i] is now. J is where it
2077 k = temp_stack.top - (regno - FIRST_STACK_REG);
2079 - (REGNO (recog_data.operand[i]) - FIRST_STACK_REG));
2081 temp = temp_stack.reg[k];
2082 temp_stack.reg[k] = temp_stack.reg[j];
2083 temp_stack.reg[j] = temp;
2087 /* Emit insns before INSN to make sure the reg-stack is in the right
2090 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
2092 /* Make the needed input register substitutions. Do death notes and
2093 clobbers too, because these are for inputs, not outputs. */
2095 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2096 if (STACK_REG_P (recog_data.operand[i]))
2098 int regnum = get_hard_regnum (regstack, recog_data.operand[i]);
2100 gcc_assert (regnum >= 0);
2102 replace_reg (recog_data.operand_loc[i], regnum);
2105 for (i = 0; i < n_notes; i++)
2106 if (note_kind[i] == REG_DEAD)
2108 int regnum = get_hard_regnum (regstack, note_reg[i]);
2110 gcc_assert (regnum >= 0);
2112 replace_reg (note_loc[i], regnum);
2115 for (i = 0; i < n_clobbers; i++)
2117 /* It's OK for a CLOBBER to reference a reg that is not live.
2118 Don't try to replace it in that case. */
2119 int regnum = get_hard_regnum (regstack, clobber_reg[i]);
2123 /* Sigh - clobbers always have QImode. But replace_reg knows
2124 that these regs can't be MODE_INT and will assert. Just put
2125 the right reg there without calling replace_reg. */
2127 *clobber_loc[i] = FP_MODE_REG (regnum, DFmode);
2131 /* Now remove from REGSTACK any inputs that the asm implicitly popped. */
2133 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2134 if (STACK_REG_P (recog_data.operand[i]))
2136 /* An input reg is implicitly popped if it is tied to an
2137 output, or if there is a CLOBBER for it. */
2140 for (j = 0; j < n_clobbers; j++)
2141 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
2144 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
2146 /* recog_data.operand[i] might not be at the top of stack.
2147 But that's OK, because all we need to do is pop the
2148 right number of regs off of the top of the reg-stack.
2149 record_asm_stack_regs guaranteed that all implicitly
2150 popped regs were grouped at the top of the reg-stack. */
2152 CLEAR_HARD_REG_BIT (regstack->reg_set,
2153 regstack->reg[regstack->top]);
2158 /* Now add to REGSTACK any outputs that the asm implicitly pushed.
2159 Note that there isn't any need to substitute register numbers.
2160 ??? Explain why this is true. */
2162 for (i = LAST_STACK_REG; i >= FIRST_STACK_REG; i--)
2164 /* See if there is an output for this hard reg. */
2167 for (j = 0; j < n_outputs; j++)
2168 if (STACK_REG_P (recog_data.operand[j])
2169 && REGNO (recog_data.operand[j]) == (unsigned) i)
2171 regstack->reg[++regstack->top] = i;
2172 SET_HARD_REG_BIT (regstack->reg_set, i);
2177 /* Now emit a pop insn for any REG_UNUSED output, or any REG_DEAD
2178 input that the asm didn't implicitly pop. If the asm didn't
2179 implicitly pop an input reg, that reg will still be live.
2181 Note that we can't use find_regno_note here: the register numbers
2182 in the death notes have already been substituted. */
2184 for (i = 0; i < n_outputs; i++)
2185 if (STACK_REG_P (recog_data.operand[i]))
2189 for (j = 0; j < n_notes; j++)
2190 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2191 && note_kind[j] == REG_UNUSED)
2193 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2199 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2200 if (STACK_REG_P (recog_data.operand[i]))
2204 for (j = 0; j < n_notes; j++)
2205 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2206 && note_kind[j] == REG_DEAD
2207 && TEST_HARD_REG_BIT (regstack->reg_set,
2208 REGNO (recog_data.operand[i])))
2210 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2217 /* Substitute stack hard reg numbers for stack virtual registers in
2218 INSN. Non-stack register numbers are not changed. REGSTACK is the
2219 current stack content. Insns may be emitted as needed to arrange the
2220 stack for the 387 based on the contents of the insn. Return whether
2221 a control flow insn was deleted in the process. */
2224 subst_stack_regs (rtx insn, stack regstack)
2226 rtx *note_link, note;
2227 bool control_flow_insn_deleted = false;
2232 int top = regstack->top;
2234 /* If there are any floating point parameters to be passed in
2235 registers for this call, make sure they are in the right
2240 straighten_stack (insn, regstack);
2242 /* Now mark the arguments as dead after the call. */
2244 while (regstack->top >= 0)
2246 CLEAR_HARD_REG_BIT (regstack->reg_set, FIRST_STACK_REG + regstack->top);
2252 /* Do the actual substitution if any stack regs are mentioned.
2253 Since we only record whether entire insn mentions stack regs, and
2254 subst_stack_regs_pat only works for patterns that contain stack regs,
2255 we must check each pattern in a parallel here. A call_value_pop could
2258 if (stack_regs_mentioned (insn))
2260 int n_operands = asm_noperands (PATTERN (insn));
2261 if (n_operands >= 0)
2263 /* This insn is an `asm' with operands. Decode the operands,
2264 decide how many are inputs, and do register substitution.
2265 Any REG_UNUSED notes will be handled by subst_asm_stack_regs. */
2267 subst_asm_stack_regs (insn, regstack);
2268 return control_flow_insn_deleted;
2271 if (GET_CODE (PATTERN (insn)) == PARALLEL)
2272 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
2274 if (stack_regs_mentioned_p (XVECEXP (PATTERN (insn), 0, i)))
2276 if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == CLOBBER)
2277 XVECEXP (PATTERN (insn), 0, i)
2278 = shallow_copy_rtx (XVECEXP (PATTERN (insn), 0, i));
2279 control_flow_insn_deleted
2280 |= subst_stack_regs_pat (insn, regstack,
2281 XVECEXP (PATTERN (insn), 0, i));
2285 control_flow_insn_deleted
2286 |= subst_stack_regs_pat (insn, regstack, PATTERN (insn));
2289 /* subst_stack_regs_pat may have deleted a no-op insn. If so, any
2290 REG_UNUSED will already have been dealt with, so just return. */
2292 if (NOTE_P (insn) || INSN_DELETED_P (insn))
2293 return control_flow_insn_deleted;
2295 /* If this a noreturn call, we can't insert pop insns after it.
2296 Instead, reset the stack state to empty. */
2298 && find_reg_note (insn, REG_NORETURN, NULL))
2301 CLEAR_HARD_REG_SET (regstack->reg_set);
2302 return control_flow_insn_deleted;
2305 /* If there is a REG_UNUSED note on a stack register on this insn,
2306 the indicated reg must be popped. The REG_UNUSED note is removed,
2307 since the form of the newly emitted pop insn references the reg,
2308 making it no longer `unset'. */
2310 note_link = ®_NOTES (insn);
2311 for (note = *note_link; note; note = XEXP (note, 1))
2312 if (REG_NOTE_KIND (note) == REG_UNUSED && STACK_REG_P (XEXP (note, 0)))
2314 *note_link = XEXP (note, 1);
2315 insn = emit_pop_insn (insn, regstack, XEXP (note, 0), EMIT_AFTER);
2318 note_link = &XEXP (note, 1);
2320 return control_flow_insn_deleted;
2323 /* Change the organization of the stack so that it fits a new basic
2324 block. Some registers might have to be popped, but there can never be
2325 a register live in the new block that is not now live.
2327 Insert any needed insns before or after INSN, as indicated by
2328 WHERE. OLD is the original stack layout, and NEW is the desired
2329 form. OLD is updated to reflect the code emitted, i.e., it will be
2330 the same as NEW upon return.
2332 This function will not preserve block_end[]. But that information
2333 is no longer needed once this has executed. */
2336 change_stack (rtx insn, stack old, stack new, enum emit_where where)
2341 /* Stack adjustments for the first insn in a block update the
2342 current_block's stack_in instead of inserting insns directly.
2343 compensate_edges will add the necessary code later. */
2346 && where == EMIT_BEFORE)
2348 BLOCK_INFO (current_block)->stack_in = *new;
2349 starting_stack_p = false;
2354 /* We will be inserting new insns "backwards". If we are to insert
2355 after INSN, find the next insn, and insert before it. */
2357 if (where == EMIT_AFTER)
2359 if (current_block && BB_END (current_block) == insn)
2361 insn = NEXT_INSN (insn);
2364 /* Pop any registers that are not needed in the new block. */
2366 /* If the destination block's stack already has a specified layout
2367 and contains two or more registers, use a more intelligent algorithm
2368 to pop registers that minimizes the number number of fxchs below. */
2371 bool slots[REG_STACK_SIZE];
2372 int pops[REG_STACK_SIZE];
2373 int next, dest, topsrc;
2375 /* First pass to determine the free slots. */
2376 for (reg = 0; reg <= new->top; reg++)
2377 slots[reg] = TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]);
2379 /* Second pass to allocate preferred slots. */
2381 for (reg = old->top; reg > new->top; reg--)
2382 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2385 for (next = 0; next <= new->top; next++)
2386 if (!slots[next] && new->reg[next] == old->reg[reg])
2388 /* If this is a preference for the new top of stack, record
2389 the fact by remembering it's old->reg in topsrc. */
2390 if (next == new->top)
2401 /* Intentionally, avoid placing the top of stack in it's correct
2402 location, if we still need to permute the stack below and we
2403 can usefully place it somewhere else. This is the case if any
2404 slot is still unallocated, in which case we should place the
2405 top of stack there. */
2407 for (reg = 0; reg < new->top; reg++)
2411 slots[new->top] = false;
2416 /* Third pass allocates remaining slots and emits pop insns. */
2418 for (reg = old->top; reg > new->top; reg--)
2423 /* Find next free slot. */
2428 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[dest], DFmode),
2434 /* The following loop attempts to maximize the number of times we
2435 pop the top of the stack, as this permits the use of the faster
2436 ffreep instruction on platforms that support it. */
2440 for (reg = 0; reg <= old->top; reg++)
2441 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2445 while (old->top >= live)
2446 if (TEST_HARD_REG_BIT (new->reg_set, old->reg[old->top]))
2448 while (TEST_HARD_REG_BIT (new->reg_set, old->reg[next]))
2450 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[next], DFmode),
2454 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[old->top], DFmode),
2460 /* If the new block has never been processed, then it can inherit
2461 the old stack order. */
2463 new->top = old->top;
2464 memcpy (new->reg, old->reg, sizeof (new->reg));
2468 /* This block has been entered before, and we must match the
2469 previously selected stack order. */
2471 /* By now, the only difference should be the order of the stack,
2472 not their depth or liveliness. */
2474 GO_IF_HARD_REG_EQUAL (old->reg_set, new->reg_set, win);
2477 gcc_assert (old->top == new->top);
2479 /* If the stack is not empty (new->top != -1), loop here emitting
2480 swaps until the stack is correct.
2482 The worst case number of swaps emitted is N + 2, where N is the
2483 depth of the stack. In some cases, the reg at the top of
2484 stack may be correct, but swapped anyway in order to fix
2485 other regs. But since we never swap any other reg away from
2486 its correct slot, this algorithm will converge. */
2491 /* Swap the reg at top of stack into the position it is
2492 supposed to be in, until the correct top of stack appears. */
2494 while (old->reg[old->top] != new->reg[new->top])
2496 for (reg = new->top; reg >= 0; reg--)
2497 if (new->reg[reg] == old->reg[old->top])
2500 gcc_assert (reg != -1);
2502 emit_swap_insn (insn, old,
2503 FP_MODE_REG (old->reg[reg], DFmode));
2506 /* See if any regs remain incorrect. If so, bring an
2507 incorrect reg to the top of stack, and let the while loop
2510 for (reg = new->top; reg >= 0; reg--)
2511 if (new->reg[reg] != old->reg[reg])
2513 emit_swap_insn (insn, old,
2514 FP_MODE_REG (old->reg[reg], DFmode));
2519 /* At this point there must be no differences. */
2521 for (reg = old->top; reg >= 0; reg--)
2522 gcc_assert (old->reg[reg] == new->reg[reg]);
2526 BB_END (current_block) = PREV_INSN (insn);
2529 /* Print stack configuration. */
2532 print_stack (FILE *file, stack s)
2538 fprintf (file, "uninitialized\n");
2539 else if (s->top == -1)
2540 fprintf (file, "empty\n");
2545 for (i = 0; i <= s->top; ++i)
2546 fprintf (file, "%d ", s->reg[i]);
2547 fputs ("]\n", file);
2551 /* This function was doing life analysis. We now let the regular live
2552 code do it's job, so we only need to check some extra invariants
2553 that reg-stack expects. Primary among these being that all registers
2554 are initialized before use.
2556 The function returns true when code was emitted to CFG edges and
2557 commit_edge_insertions needs to be called. */
2560 convert_regs_entry (void)
2566 /* Load something into each stack register live at function entry.
2567 Such live registers can be caused by uninitialized variables or
2568 functions not returning values on all paths. In order to keep
2569 the push/pop code happy, and to not scrog the register stack, we
2570 must put something in these registers. Use a QNaN.
2572 Note that we are inserting converted code here. This code is
2573 never seen by the convert_regs pass. */
2575 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2577 basic_block block = e->dest;
2578 block_info bi = BLOCK_INFO (block);
2581 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2582 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2586 bi->stack_in.reg[++top] = reg;
2588 init = gen_rtx_SET (VOIDmode,
2589 FP_MODE_REG (FIRST_STACK_REG, SFmode),
2591 insert_insn_on_edge (init, e);
2595 bi->stack_in.top = top;
2601 /* Construct the desired stack for function exit. This will either
2602 be `empty', or the function return value at top-of-stack. */
2605 convert_regs_exit (void)
2607 int value_reg_low, value_reg_high;
2611 retvalue = stack_result (current_function_decl);
2612 value_reg_low = value_reg_high = -1;
2615 value_reg_low = REGNO (retvalue);
2616 value_reg_high = value_reg_low
2617 + hard_regno_nregs[value_reg_low][GET_MODE (retvalue)] - 1;
2620 output_stack = &BLOCK_INFO (EXIT_BLOCK_PTR)->stack_in;
2621 if (value_reg_low == -1)
2622 output_stack->top = -1;
2627 output_stack->top = value_reg_high - value_reg_low;
2628 for (reg = value_reg_low; reg <= value_reg_high; ++reg)
2630 output_stack->reg[value_reg_high - reg] = reg;
2631 SET_HARD_REG_BIT (output_stack->reg_set, reg);
2636 /* Copy the stack info from the end of edge E's source block to the
2637 start of E's destination block. */
2640 propagate_stack (edge e)
2642 stack src_stack = &BLOCK_INFO (e->src)->stack_out;
2643 stack dest_stack = &BLOCK_INFO (e->dest)->stack_in;
2646 /* Preserve the order of the original stack, but check whether
2647 any pops are needed. */
2648 dest_stack->top = -1;
2649 for (reg = 0; reg <= src_stack->top; ++reg)
2650 if (TEST_HARD_REG_BIT (dest_stack->reg_set, src_stack->reg[reg]))
2651 dest_stack->reg[++dest_stack->top] = src_stack->reg[reg];
2655 /* Adjust the stack of edge E's source block on exit to match the stack
2656 of it's target block upon input. The stack layouts of both blocks
2657 should have been defined by now. */
2660 compensate_edge (edge e)
2662 basic_block source = e->src, target = e->dest;
2663 stack target_stack = &BLOCK_INFO (target)->stack_in;
2664 stack source_stack = &BLOCK_INFO (source)->stack_out;
2665 struct stack_def regstack;
2669 fprintf (dump_file, "Edge %d->%d: ", source->index, target->index);
2671 gcc_assert (target_stack->top != -2);
2673 /* Check whether stacks are identical. */
2674 if (target_stack->top == source_stack->top)
2676 for (reg = target_stack->top; reg >= 0; --reg)
2677 if (target_stack->reg[reg] != source_stack->reg[reg])
2683 fprintf (dump_file, "no changes needed\n");
2690 fprintf (dump_file, "correcting stack to ");
2691 print_stack (dump_file, target_stack);
2694 /* Abnormal calls may appear to have values live in st(0), but the
2695 abnormal return path will not have actually loaded the values. */
2696 if (e->flags & EDGE_ABNORMAL_CALL)
2698 /* Assert that the lifetimes are as we expect -- one value
2699 live at st(0) on the end of the source block, and no
2700 values live at the beginning of the destination block.
2701 For complex return values, we may have st(1) live as well. */
2702 gcc_assert (source_stack->top == 0 || source_stack->top == 1);
2703 gcc_assert (target_stack->top == -1);
2707 /* Handle non-call EH edges specially. The normal return path have
2708 values in registers. These will be popped en masse by the unwind
2710 if (e->flags & EDGE_EH)
2712 gcc_assert (target_stack->top == -1);
2716 /* We don't support abnormal edges. Global takes care to
2717 avoid any live register across them, so we should never
2718 have to insert instructions on such edges. */
2719 gcc_assert (! (e->flags & EDGE_ABNORMAL));
2721 /* Make a copy of source_stack as change_stack is destructive. */
2722 regstack = *source_stack;
2724 /* It is better to output directly to the end of the block
2725 instead of to the edge, because emit_swap can do minimal
2726 insn scheduling. We can do this when there is only one
2727 edge out, and it is not abnormal. */
2728 if (EDGE_COUNT (source->succs) == 1)
2730 current_block = source;
2731 change_stack (BB_END (source), ®stack, target_stack,
2732 (JUMP_P (BB_END (source)) ? EMIT_BEFORE : EMIT_AFTER));
2738 current_block = NULL;
2741 /* ??? change_stack needs some point to emit insns after. */
2742 after = emit_note (NOTE_INSN_DELETED);
2744 change_stack (after, ®stack, target_stack, EMIT_BEFORE);
2749 insert_insn_on_edge (seq, e);
2755 /* Traverse all non-entry edges in the CFG, and emit the necessary
2756 edge compensation code to change the stack from stack_out of the
2757 source block to the stack_in of the destination block. */
2760 compensate_edges (void)
2762 bool inserted = false;
2765 starting_stack_p = false;
2768 if (bb != ENTRY_BLOCK_PTR)
2773 FOR_EACH_EDGE (e, ei, bb->succs)
2774 inserted |= compensate_edge (e);
2779 /* Select the better of two edges E1 and E2 to use to determine the
2780 stack layout for their shared destination basic block. This is
2781 typically the more frequently executed. The edge E1 may be NULL
2782 (in which case E2 is returned), but E2 is always non-NULL. */
2785 better_edge (edge e1, edge e2)
2790 if (EDGE_FREQUENCY (e1) > EDGE_FREQUENCY (e2))
2792 if (EDGE_FREQUENCY (e1) < EDGE_FREQUENCY (e2))
2795 if (e1->count > e2->count)
2797 if (e1->count < e2->count)
2800 /* Prefer critical edges to minimize inserting compensation code on
2803 if (EDGE_CRITICAL_P (e1) != EDGE_CRITICAL_P (e2))
2804 return EDGE_CRITICAL_P (e1) ? e1 : e2;
2806 /* Avoid non-deterministic behavior. */
2807 return (e1->src->index < e2->src->index) ? e1 : e2;
2810 /* Convert stack register references in one block. */
2813 convert_regs_1 (basic_block block)
2815 struct stack_def regstack;
2816 block_info bi = BLOCK_INFO (block);
2819 bool control_flow_insn_deleted = false;
2821 any_malformed_asm = false;
2823 /* Choose an initial stack layout, if one hasn't already been chosen. */
2824 if (bi->stack_in.top == -2)
2826 edge e, beste = NULL;
2829 /* Select the best incoming edge (typically the most frequent) to
2830 use as a template for this basic block. */
2831 FOR_EACH_EDGE (e, ei, block->preds)
2832 if (BLOCK_INFO (e->src)->done)
2833 beste = better_edge (beste, e);
2836 propagate_stack (beste);
2839 /* No predecessors. Create an arbitrary input stack. */
2840 bi->stack_in.top = -1;
2841 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2842 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2843 bi->stack_in.reg[++bi->stack_in.top] = reg;
2849 fprintf (dump_file, "\nBasic block %d\nInput stack: ", block->index);
2850 print_stack (dump_file, &bi->stack_in);
2853 /* Process all insns in this block. Keep track of NEXT so that we
2854 don't process insns emitted while substituting in INSN. */
2855 current_block = block;
2856 next = BB_HEAD (block);
2857 regstack = bi->stack_in;
2858 starting_stack_p = true;
2863 next = NEXT_INSN (insn);
2865 /* Ensure we have not missed a block boundary. */
2867 if (insn == BB_END (block))
2870 /* Don't bother processing unless there is a stack reg
2871 mentioned or if it's a CALL_INSN. */
2872 if (stack_regs_mentioned (insn)
2877 fprintf (dump_file, " insn %d input stack: ",
2879 print_stack (dump_file, ®stack);
2881 control_flow_insn_deleted |= subst_stack_regs (insn, ®stack);
2882 starting_stack_p = false;
2889 fprintf (dump_file, "Expected live registers [");
2890 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2891 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg))
2892 fprintf (dump_file, " %d", reg);
2893 fprintf (dump_file, " ]\nOutput stack: ");
2894 print_stack (dump_file, ®stack);
2897 insn = BB_END (block);
2899 insn = PREV_INSN (insn);
2901 /* If the function is declared to return a value, but it returns one
2902 in only some cases, some registers might come live here. Emit
2903 necessary moves for them. */
2905 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2907 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg)
2908 && ! TEST_HARD_REG_BIT (regstack.reg_set, reg))
2913 fprintf (dump_file, "Emitting insn initializing reg %d\n", reg);
2915 set = gen_rtx_SET (VOIDmode, FP_MODE_REG (reg, SFmode), not_a_num);
2916 insn = emit_insn_after (set, insn);
2917 control_flow_insn_deleted |= subst_stack_regs (insn, ®stack);
2921 /* Amongst the insns possibly deleted during the substitution process above,
2922 might have been the only trapping insn in the block. We purge the now
2923 possibly dead EH edges here to avoid an ICE from fixup_abnormal_edges,
2924 called at the end of convert_regs. The order in which we process the
2925 blocks ensures that we never delete an already processed edge.
2927 Note that, at this point, the CFG may have been damaged by the emission
2928 of instructions after an abnormal call, which moves the basic block end
2929 (and is the reason why we call fixup_abnormal_edges later). So we must
2930 be sure that the trapping insn has been deleted before trying to purge
2931 dead edges, otherwise we risk purging valid edges.
2933 ??? We are normally supposed not to delete trapping insns, so we pretend
2934 that the insns deleted above don't actually trap. It would have been
2935 better to detect this earlier and avoid creating the EH edge in the first
2936 place, still, but we don't have enough information at that time. */
2938 if (control_flow_insn_deleted)
2939 purge_dead_edges (block);
2941 /* Something failed if the stack lives don't match. If we had malformed
2942 asms, we zapped the instruction itself, but that didn't produce the
2943 same pattern of register kills as before. */
2944 GO_IF_HARD_REG_EQUAL (regstack.reg_set, bi->out_reg_set, win);
2945 gcc_assert (any_malformed_asm);
2947 bi->stack_out = regstack;
2951 /* Convert registers in all blocks reachable from BLOCK. */
2954 convert_regs_2 (basic_block block)
2956 basic_block *stack, *sp;
2958 /* We process the blocks in a top-down manner, in a way such that one block
2959 is only processed after all its predecessors. The number of predecessors
2960 of every block has already been computed. */
2962 stack = XNEWVEC (basic_block, n_basic_blocks);
2974 /* Processing BLOCK is achieved by convert_regs_1, which may purge
2975 some dead EH outgoing edge after the deletion of the trapping
2976 insn inside the block. Since the number of predecessors of
2977 BLOCK's successors was computed based on the initial edge set,
2978 we check the necessity to process some of these successors
2979 before such an edge deletion may happen. However, there is
2980 a pitfall: if BLOCK is the only predecessor of a successor and
2981 the edge between them happens to be deleted, the successor
2982 becomes unreachable and should not be processed. The problem
2983 is that there is no way to preventively detect this case so we
2984 stack the successor in all cases and hand over the task of
2985 fixing up the discrepancy to convert_regs_1. */
2987 FOR_EACH_EDGE (e, ei, block->succs)
2988 if (! (e->flags & EDGE_DFS_BACK))
2990 BLOCK_INFO (e->dest)->predecessors--;
2991 if (!BLOCK_INFO (e->dest)->predecessors)
2995 convert_regs_1 (block);
2997 while (sp != stack);
3002 /* Traverse all basic blocks in a function, converting the register
3003 references in each insn from the "flat" register file that gcc uses,
3004 to the stack-like registers the 387 uses. */
3014 /* Initialize uninitialized registers on function entry. */
3015 inserted = convert_regs_entry ();
3017 /* Construct the desired stack for function exit. */
3018 convert_regs_exit ();
3019 BLOCK_INFO (EXIT_BLOCK_PTR)->done = 1;
3021 /* ??? Future: process inner loops first, and give them arbitrary
3022 initial stacks which emit_swap_insn can modify. This ought to
3023 prevent double fxch that often appears at the head of a loop. */
3025 /* Process all blocks reachable from all entry points. */
3026 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3027 convert_regs_2 (e->dest);
3029 /* ??? Process all unreachable blocks. Though there's no excuse
3030 for keeping these even when not optimizing. */
3033 block_info bi = BLOCK_INFO (b);
3039 inserted |= compensate_edges ();
3041 clear_aux_for_blocks ();
3043 fixup_abnormal_edges ();
3045 commit_edge_insertions ();
3048 fputc ('\n', dump_file);
3051 /* Convert register usage from "flat" register file usage to a "stack
3052 register file. FILE is the dump file, if used.
3054 Construct a CFG and run life analysis. Then convert each insn one
3055 by one. Run a last cleanup_cfg pass, if optimizing, to eliminate
3056 code duplication created when the converter inserts pop insns on
3066 /* Clean up previous run. */
3067 if (stack_regs_mentioned_data != NULL)
3068 VEC_free (char, heap, stack_regs_mentioned_data);
3070 /* See if there is something to do. Flow analysis is quite
3071 expensive so we might save some compilation time. */
3072 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
3073 if (regs_ever_live[i])
3075 if (i > LAST_STACK_REG)
3078 /* Ok, floating point instructions exist. If not optimizing,
3079 build the CFG and run life analysis.
3080 Also need to rebuild life when superblock scheduling is done
3081 as it don't update liveness yet. */
3083 || ((flag_sched2_use_superblocks || flag_sched2_use_traces)
3084 && flag_schedule_insns_after_reload))
3086 count_or_remove_death_notes (NULL, 1);
3087 life_analysis (PROP_DEATH_NOTES);
3089 mark_dfs_back_edges ();
3091 /* Set up block info for each basic block. */
3092 alloc_aux_for_blocks (sizeof (struct block_info_def));
3095 block_info bi = BLOCK_INFO (bb);
3100 FOR_EACH_EDGE (e, ei, bb->preds)
3101 if (!(e->flags & EDGE_DFS_BACK)
3102 && e->src != ENTRY_BLOCK_PTR)
3105 /* Set current register status at last instruction `uninitialized'. */
3106 bi->stack_in.top = -2;
3108 /* Copy live_at_end and live_at_start into temporaries. */
3109 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; reg++)
3111 if (REGNO_REG_SET_P (bb->il.rtl->global_live_at_end, reg))
3112 SET_HARD_REG_BIT (bi->out_reg_set, reg);
3113 if (REGNO_REG_SET_P (bb->il.rtl->global_live_at_start, reg))
3114 SET_HARD_REG_BIT (bi->stack_in.reg_set, reg);
3118 /* Create the replacement registers up front. */
3119 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
3121 enum machine_mode mode;
3122 for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT);
3124 mode = GET_MODE_WIDER_MODE (mode))
3125 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
3126 for (mode = GET_CLASS_NARROWEST_MODE (MODE_COMPLEX_FLOAT);
3128 mode = GET_MODE_WIDER_MODE (mode))
3129 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
3132 ix86_flags_rtx = gen_rtx_REG (CCmode, FLAGS_REG);
3134 /* A QNaN for initializing uninitialized variables.
3136 ??? We can't load from constant memory in PIC mode, because
3137 we're inserting these instructions before the prologue and
3138 the PIC register hasn't been set up. In that case, fall back
3139 on zero, which we can get from `ldz'. */
3142 not_a_num = CONST0_RTX (SFmode);
3145 not_a_num = gen_lowpart (SFmode, GEN_INT (0x7fc00000));
3146 not_a_num = force_const_mem (SFmode, not_a_num);
3149 /* Allocate a cache for stack_regs_mentioned. */
3150 max_uid = get_max_uid ();
3151 stack_regs_mentioned_data = VEC_alloc (char, heap, max_uid + 1);
3152 memset (VEC_address (char, stack_regs_mentioned_data),
3153 0, sizeof (char) * max_uid + 1);
3157 free_aux_for_blocks ();
3160 #endif /* STACK_REGS */
3163 gate_handle_stack_regs (void)
3172 /* Convert register usage from flat register file usage to a stack
3175 rest_of_handle_stack_regs (void)
3178 if (reg_to_stack () && optimize)
3180 regstack_completed = 1;
3181 if (cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_POST_REGSTACK
3182 | (flag_crossjumping ? CLEANUP_CROSSJUMP : 0))
3183 && (flag_reorder_blocks || flag_reorder_blocks_and_partition))
3185 reorder_basic_blocks (0);
3186 cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_POST_REGSTACK);
3190 regstack_completed = 1;
3195 struct tree_opt_pass pass_stack_regs =
3198 gate_handle_stack_regs, /* gate */
3199 rest_of_handle_stack_regs, /* execute */
3202 0, /* static_pass_number */
3203 TV_REG_STACK, /* tv_id */
3204 0, /* properties_required */
3205 0, /* properties_provided */
3206 0, /* properties_destroyed */
3207 0, /* todo_flags_start */
3209 TODO_ggc_collect, /* todo_flags_finish */