1 /* Register to Stack convert for GNU compiler.
2 Copyright (C) 1992, 93-98, 1999 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
21 /* This pass converts stack-like registers from the "flat register
22 file" model that gcc uses, to a stack convention that the 387 uses.
24 * The form of the input:
26 On input, the function consists of insn that have had their
27 registers fully allocated to a set of "virtual" registers. Note that
28 the word "virtual" is used differently here than elsewhere in gcc: for
29 each virtual stack reg, there is a hard reg, but the mapping between
30 them is not known until this pass is run. On output, hard register
31 numbers have been substituted, and various pop and exchange insns have
32 been emitted. The hard register numbers and the virtual register
33 numbers completely overlap - before this pass, all stack register
34 numbers are virtual, and afterward they are all hard.
36 The virtual registers can be manipulated normally by gcc, and their
37 semantics are the same as for normal registers. After the hard
38 register numbers are substituted, the semantics of an insn containing
39 stack-like regs are not the same as for an insn with normal regs: for
40 instance, it is not safe to delete an insn that appears to be a no-op
41 move. In general, no insn containing hard regs should be changed
42 after this pass is done.
44 * The form of the output:
46 After this pass, hard register numbers represent the distance from
47 the current top of stack to the desired register. A reference to
48 FIRST_STACK_REG references the top of stack, FIRST_STACK_REG + 1,
49 represents the register just below that, and so forth. Also, REG_DEAD
50 notes indicate whether or not a stack register should be popped.
52 A "swap" insn looks like a parallel of two patterns, where each
53 pattern is a SET: one sets A to B, the other B to A.
55 A "push" or "load" insn is a SET whose SET_DEST is FIRST_STACK_REG
56 and whose SET_DEST is REG or MEM. Any other SET_DEST, such as PLUS,
57 will replace the existing stack top, not push a new value.
59 A store insn is a SET whose SET_DEST is FIRST_STACK_REG, and whose
60 SET_SRC is REG or MEM.
62 The case where the SET_SRC and SET_DEST are both FIRST_STACK_REG
63 appears ambiguous. As a special case, the presence of a REG_DEAD note
64 for FIRST_STACK_REG differentiates between a load insn and a pop.
66 If a REG_DEAD is present, the insn represents a "pop" that discards
67 the top of the register stack. If there is no REG_DEAD note, then the
68 insn represents a "dup" or a push of the current top of stack onto the
73 Existing REG_DEAD and REG_UNUSED notes for stack registers are
74 deleted and recreated from scratch. REG_DEAD is never created for a
75 SET_DEST, only REG_UNUSED.
79 There are several rules on the usage of stack-like regs in
80 asm_operands insns. These rules apply only to the operands that are
83 1. Given a set of input regs that die in an asm_operands, it is
84 necessary to know which are implicitly popped by the asm, and
85 which must be explicitly popped by gcc.
87 An input reg that is implicitly popped by the asm must be
88 explicitly clobbered, unless it is constrained to match an
91 2. For any input reg that is implicitly popped by an asm, it is
92 necessary to know how to adjust the stack to compensate for the pop.
93 If any non-popped input is closer to the top of the reg-stack than
94 the implicitly popped reg, it would not be possible to know what the
95 stack looked like - it's not clear how the rest of the stack "slides
98 All implicitly popped input regs must be closer to the top of
99 the reg-stack than any input that is not implicitly popped.
101 3. It is possible that if an input dies in an insn, reload might
102 use the input reg for an output reload. Consider this example:
104 asm ("foo" : "=t" (a) : "f" (b));
106 This asm says that input B is not popped by the asm, and that
107 the asm pushes a result onto the reg-stack, ie, the stack is one
108 deeper after the asm than it was before. But, it is possible that
109 reload will think that it can use the same reg for both the input and
110 the output, if input B dies in this insn.
112 If any input operand uses the "f" constraint, all output reg
113 constraints must use the "&" earlyclobber.
115 The asm above would be written as
117 asm ("foo" : "=&t" (a) : "f" (b));
119 4. Some operands need to be in particular places on the stack. All
120 output operands fall in this category - there is no other way to
121 know which regs the outputs appear in unless the user indicates
122 this in the constraints.
124 Output operands must specifically indicate which reg an output
125 appears in after an asm. "=f" is not allowed: the operand
126 constraints must select a class with a single reg.
128 5. Output operands may not be "inserted" between existing stack regs.
129 Since no 387 opcode uses a read/write operand, all output operands
130 are dead before the asm_operands, and are pushed by the asm_operands.
131 It makes no sense to push anywhere but the top of the reg-stack.
133 Output operands must start at the top of the reg-stack: output
134 operands may not "skip" a reg.
136 6. Some asm statements may need extra stack space for internal
137 calculations. This can be guaranteed by clobbering stack registers
138 unrelated to the inputs and outputs.
140 Here are a couple of reasonable asms to want to write. This asm
141 takes one input, which is internally popped, and produces two outputs.
143 asm ("fsincos" : "=t" (cos), "=u" (sin) : "0" (inp));
145 This asm takes two inputs, which are popped by the fyl2xp1 opcode,
146 and replaces them with one output. The user must code the "st(1)"
147 clobber for reg-stack.c to know that fyl2xp1 pops both inputs.
149 asm ("fyl2xp1" : "=t" (result) : "0" (x), "u" (y) : "st(1)");
158 #include "function.h"
159 #include "insn-config.h"
161 #include "hard-reg-set.h"
163 #include "insn-flags.h"
167 #include "basic-block.h"
172 #define REG_STACK_SIZE (LAST_STACK_REG - FIRST_STACK_REG + 1)
174 /* This is the basic stack record. TOP is an index into REG[] such
175 that REG[TOP] is the top of stack. If TOP is -1 the stack is empty.
177 If TOP is -2, REG[] is not yet initialized. Stack initialization
178 consists of placing each live reg in array `reg' and setting `top'
181 REG_SET indicates which registers are live. */
183 typedef struct stack_def
185 int top; /* index to top stack element */
186 HARD_REG_SET reg_set; /* set of live registers */
187 char reg[REG_STACK_SIZE]; /* register - stack mapping */
190 /* This is used to carry information about basic blocks. It is
191 attached to the AUX field of the standard CFG block. */
193 typedef struct block_info_def
195 struct stack_def stack_in; /* Input stack configuration. */
196 HARD_REG_SET out_reg_set; /* Stack regs live on output. */
197 int done; /* True if block already converted. */
200 #define BLOCK_INFO(B) ((block_info) (B)->aux)
202 /* Passed to change_stack to indicate where to emit insns. */
209 /* We use this array to cache info about insns, because otherwise we
210 spend too much time in stack_regs_mentioned_p.
212 Indexed by insn UIDs. A value of zero is uninitialized, one indicates
213 the insn uses stack registers, two indicates the insn does not use
215 static varray_type stack_regs_mentioned_data;
217 /* The block we're currently working on. */
218 static basic_block current_block;
220 /* This is the register file for all register after conversion */
222 FP_mode_reg[LAST_STACK_REG+1-FIRST_STACK_REG][(int) MAX_MACHINE_MODE];
224 #define FP_MODE_REG(regno,mode) \
225 (FP_mode_reg[(regno)-FIRST_STACK_REG][(int)(mode)])
227 /* Used to initialize uninitialized registers. */
230 /* Forward declarations */
232 static int stack_regs_mentioned_p PROTO((rtx pat));
233 static void straighten_stack PROTO((rtx, stack));
234 static void pop_stack PROTO((stack, int));
235 static rtx *get_true_reg PROTO((rtx *));
237 static int check_asm_stack_operands PROTO((rtx));
238 static int get_asm_operand_n_inputs PROTO((rtx));
239 static rtx stack_result PROTO((tree));
240 static void replace_reg PROTO((rtx *, int));
241 static void remove_regno_note PROTO((rtx, enum reg_note, int));
242 static int get_hard_regnum PROTO((stack, rtx));
243 static void delete_insn_for_stacker PROTO((rtx));
244 static rtx emit_pop_insn PROTO((rtx, stack, rtx,
246 static void emit_swap_insn PROTO((rtx, stack, rtx));
247 static void move_for_stack_reg PROTO((rtx, stack, rtx));
248 static int swap_rtx_condition_1 PROTO((rtx));
249 static int swap_rtx_condition PROTO((rtx));
250 static void compare_for_stack_reg PROTO((rtx, stack, rtx));
251 static void subst_stack_regs_pat PROTO((rtx, stack, rtx));
252 static void subst_asm_stack_regs PROTO((rtx, stack));
253 static void subst_stack_regs PROTO((rtx, stack));
254 static void change_stack PROTO((rtx, stack, stack,
256 static int convert_regs_entry PROTO((void));
257 static void convert_regs_exit PROTO((void));
258 static int convert_regs_1 PROTO((FILE *, basic_block));
259 static int convert_regs_2 PROTO((FILE *, basic_block));
260 static int convert_regs PROTO((FILE *));
261 static void print_stack PROTO((FILE *, stack));
263 /* Return non-zero if any stack register is mentioned somewhere within PAT. */
266 stack_regs_mentioned_p (pat)
269 register const char *fmt;
272 if (STACK_REG_P (pat))
275 fmt = GET_RTX_FORMAT (GET_CODE (pat));
276 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
282 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
283 if (stack_regs_mentioned_p (XVECEXP (pat, i, j)))
286 else if (fmt[i] == 'e' && stack_regs_mentioned_p (XEXP (pat, i)))
293 /* Return nonzero if INSN mentions stacked registers, else return zero. */
296 stack_regs_mentioned (insn)
299 unsigned int uid, max;
302 if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
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 (insn)
332 /* Search forward looking for the first use of this value.
333 Stop at block boundaries. */
334 /* ??? This really cries for BLOCK_END! */
338 insn = NEXT_INSN (insn);
342 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
343 && reg_mentioned_p (ix86_flags_rtx, PATTERN (insn)))
346 if (GET_CODE (insn) == JUMP_INSN
347 || GET_CODE (insn) == CODE_LABEL
348 || GET_CODE (insn) == CALL_INSN)
353 /* Reorganise the stack into ascending numbers,
357 straighten_stack (insn, regstack)
361 struct stack_def temp_stack;
364 /* If there is only a single register on the stack, then the stack is
365 already in increasing order and no reorganization is needed.
367 Similarly if the stack is empty. */
368 if (regstack->top <= 0)
371 COPY_HARD_REG_SET (temp_stack.reg_set, regstack->reg_set);
373 for (top = temp_stack.top = regstack->top; top >= 0; top--)
374 temp_stack.reg[top] = FIRST_STACK_REG + temp_stack.top - top;
376 change_stack (insn, regstack, &temp_stack, EMIT_AFTER);
379 /* Pop a register from the stack */
382 pop_stack (regstack, regno)
386 int top = regstack->top;
388 CLEAR_HARD_REG_BIT (regstack->reg_set, regno);
390 /* If regno was not at the top of stack then adjust stack */
391 if (regstack->reg [top] != regno)
394 for (i = regstack->top; i >= 0; i--)
395 if (regstack->reg [i] == regno)
398 for (j = i; j < top; j++)
399 regstack->reg [j] = regstack->reg [j + 1];
405 /* Convert register usage from "flat" register file usage to a "stack
406 register file. FIRST is the first insn in the function, FILE is the
409 Construct a CFG and run life analysis. Then convert each insn one
410 by one. Run a last jump_optimize pass, if optimizing, to eliminate
411 code duplication created when the converter inserts pop insns on
415 reg_to_stack (first, file)
423 /* See if there is something to do. Flow analysis is quite
424 expensive so we might save some compilation time. */
425 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
426 if (regs_ever_live[i])
428 if (i > LAST_STACK_REG)
431 /* Ok, floating point instructions exist. If not optimizing,
432 build the CFG and run life analysis. */
433 find_basic_blocks (first, max_reg_num (), file, 0);
434 count_or_remove_death_notes (NULL, 1);
435 life_analysis (first, max_reg_num (), file, 0);
437 /* Set up block info for each basic block. */
438 bi = (block_info) alloca ((n_basic_blocks + 1) * sizeof (*bi));
439 memset (bi, 0, (n_basic_blocks + 1) * sizeof (*bi));
440 for (i = n_basic_blocks - 1; i >= 0; --i)
441 BASIC_BLOCK (i)->aux = bi + i;
442 EXIT_BLOCK_PTR->aux = bi + n_basic_blocks;
444 /* Create the replacement registers up front. */
445 for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
447 enum machine_mode mode;
448 for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT);
450 mode = GET_MODE_WIDER_MODE (mode))
451 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
452 for (mode = GET_CLASS_NARROWEST_MODE (MODE_COMPLEX_FLOAT);
454 mode = GET_MODE_WIDER_MODE (mode))
455 FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
458 ix86_flags_rtx = gen_rtx_REG (CCmode, FLAGS_REG);
460 /* A QNaN for initializing uninitialized variables.
462 ??? We can't load from constant memory in PIC mode, because
463 we're insertting these instructions before the prologue and
464 the PIC register hasn't been set up. In that case, fall back
465 on zero, which we can get from `ldz'. */
468 nan = CONST0_RTX (SFmode);
471 nan = gen_lowpart (SFmode, GEN_INT (0x7fc00000));
472 nan = force_const_mem (SFmode, nan);
475 /* Allocate a cache for stack_regs_mentioned. */
476 max_uid = get_max_uid ();
477 VARRAY_CHAR_INIT (stack_regs_mentioned_data, max_uid + 1,
478 "stack_regs_mentioned cache");
480 if (convert_regs (file) && optimize)
482 jump_optimize (first, JUMP_CROSS_JUMP_DEATH_MATTERS,
483 !JUMP_NOOP_MOVES, !JUMP_AFTER_REGSCAN);
486 VARRAY_FREE (stack_regs_mentioned_data);
489 /* Check PAT, which is in INSN, for LABEL_REFs. Add INSN to the
490 label's chain of references, and note which insn contains each
494 record_label_references (insn, pat)
497 register enum rtx_code code = GET_CODE (pat);
499 register const char *fmt;
501 if (code == LABEL_REF)
503 register rtx label = XEXP (pat, 0);
506 if (GET_CODE (label) != CODE_LABEL)
509 /* If this is an undefined label, LABEL_REFS (label) contains
511 if (INSN_UID (label) == 0)
514 /* Don't make a duplicate in the code_label's chain. */
516 for (ref = LABEL_REFS (label);
518 ref = LABEL_NEXTREF (ref))
519 if (CONTAINING_INSN (ref) == insn)
522 CONTAINING_INSN (pat) = insn;
523 LABEL_NEXTREF (pat) = LABEL_REFS (label);
524 LABEL_REFS (label) = pat;
529 fmt = GET_RTX_FORMAT (code);
530 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
533 record_label_references (insn, XEXP (pat, i));
537 for (j = 0; j < XVECLEN (pat, i); j++)
538 record_label_references (insn, XVECEXP (pat, i, j));
543 /* Return a pointer to the REG expression within PAT. If PAT is not a
544 REG, possible enclosed by a conversion rtx, return the inner part of
545 PAT that stopped the search. */
552 switch (GET_CODE (*pat))
555 /* Eliminate FP subregister accesses in favour of the
556 actual FP register in use. */
559 if (FP_REG_P (subreg = SUBREG_REG (*pat)))
561 *pat = FP_MODE_REG (REGNO (subreg) + SUBREG_WORD (*pat),
570 pat = & XEXP (*pat, 0);
574 /* There are many rules that an asm statement for stack-like regs must
575 follow. Those rules are explained at the top of this file: the rule
576 numbers below refer to that explanation. */
579 check_asm_stack_operands (insn)
584 int malformed_asm = 0;
585 rtx body = PATTERN (insn);
587 char reg_used_as_output[FIRST_PSEUDO_REGISTER];
588 char implicitly_dies[FIRST_PSEUDO_REGISTER];
592 int n_inputs, n_outputs;
594 /* Find out what the constraints require. If no constraint
595 alternative matches, this asm is malformed. */
597 constrain_operands (1);
598 alt = which_alternative;
600 preprocess_constraints ();
602 n_inputs = get_asm_operand_n_inputs (body);
603 n_outputs = recog_data.n_operands - n_inputs;
608 /* Avoid further trouble with this insn. */
609 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
613 /* Strip SUBREGs here to make the following code simpler. */
614 for (i = 0; i < recog_data.n_operands; i++)
615 if (GET_CODE (recog_data.operand[i]) == SUBREG
616 && GET_CODE (SUBREG_REG (recog_data.operand[i])) == REG)
617 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
619 /* Set up CLOBBER_REG. */
623 if (GET_CODE (body) == PARALLEL)
625 clobber_reg = (rtx *) alloca (XVECLEN (body, 0) * sizeof (rtx));
627 for (i = 0; i < XVECLEN (body, 0); i++)
628 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
630 rtx clobber = XVECEXP (body, 0, i);
631 rtx reg = XEXP (clobber, 0);
633 if (GET_CODE (reg) == SUBREG && GET_CODE (SUBREG_REG (reg)) == REG)
634 reg = SUBREG_REG (reg);
636 if (STACK_REG_P (reg))
638 clobber_reg[n_clobbers] = reg;
644 /* Enforce rule #4: Output operands must specifically indicate which
645 reg an output appears in after an asm. "=f" is not allowed: the
646 operand constraints must select a class with a single reg.
648 Also enforce rule #5: Output operands must start at the top of
649 the reg-stack: output operands may not "skip" a reg. */
651 memset (reg_used_as_output, 0, sizeof (reg_used_as_output));
652 for (i = 0; i < n_outputs; i++)
653 if (STACK_REG_P (recog_data.operand[i]))
655 if (reg_class_size[(int) recog_op_alt[i][alt].class] != 1)
657 error_for_asm (insn, "Output constraint %d must specify a single register", i);
661 reg_used_as_output[REGNO (recog_data.operand[i])] = 1;
665 /* Search for first non-popped reg. */
666 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
667 if (! reg_used_as_output[i])
670 /* If there are any other popped regs, that's an error. */
671 for (; i < LAST_STACK_REG + 1; i++)
672 if (reg_used_as_output[i])
675 if (i != LAST_STACK_REG + 1)
677 error_for_asm (insn, "Output regs must be grouped at top of stack");
681 /* Enforce rule #2: All implicitly popped input regs must be closer
682 to the top of the reg-stack than any input that is not implicitly
685 memset (implicitly_dies, 0, sizeof (implicitly_dies));
686 for (i = n_outputs; i < n_outputs + n_inputs; i++)
687 if (STACK_REG_P (recog_data.operand[i]))
689 /* An input reg is implicitly popped if it is tied to an
690 output, or if there is a CLOBBER for it. */
693 for (j = 0; j < n_clobbers; j++)
694 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
697 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
698 implicitly_dies[REGNO (recog_data.operand[i])] = 1;
701 /* Search for first non-popped reg. */
702 for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
703 if (! implicitly_dies[i])
706 /* If there are any other popped regs, that's an error. */
707 for (; i < LAST_STACK_REG + 1; i++)
708 if (implicitly_dies[i])
711 if (i != LAST_STACK_REG + 1)
714 "Implicitly popped regs must be grouped at top of stack");
718 /* Enfore rule #3: If any input operand uses the "f" constraint, all
719 output constraints must use the "&" earlyclobber.
721 ??? Detect this more deterministically by having constrain_asm_operands
722 record any earlyclobber. */
724 for (i = n_outputs; i < n_outputs + n_inputs; i++)
725 if (recog_op_alt[i][alt].matches == -1)
729 for (j = 0; j < n_outputs; j++)
730 if (operands_match_p (recog_data.operand[j], recog_data.operand[i]))
733 "Output operand %d must use `&' constraint", j);
740 /* Avoid further trouble with this insn. */
741 PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
748 /* Calculate the number of inputs and outputs in BODY, an
749 asm_operands. N_OPERANDS is the total number of operands, and
750 N_INPUTS and N_OUTPUTS are pointers to ints into which the results are
754 get_asm_operand_n_inputs (body)
757 if (GET_CODE (body) == SET && GET_CODE (SET_SRC (body)) == ASM_OPERANDS)
758 return ASM_OPERANDS_INPUT_LENGTH (SET_SRC (body));
760 else if (GET_CODE (body) == ASM_OPERANDS)
761 return ASM_OPERANDS_INPUT_LENGTH (body);
763 else if (GET_CODE (body) == PARALLEL
764 && GET_CODE (XVECEXP (body, 0, 0)) == SET)
765 return ASM_OPERANDS_INPUT_LENGTH (SET_SRC (XVECEXP (body, 0, 0)));
767 else if (GET_CODE (body) == PARALLEL
768 && GET_CODE (XVECEXP (body, 0, 0)) == ASM_OPERANDS)
769 return ASM_OPERANDS_INPUT_LENGTH (XVECEXP (body, 0, 0));
774 /* If current function returns its result in an fp stack register,
775 return the REG. Otherwise, return 0. */
783 /* If the value is supposed to be returned in memory, then clearly
784 it is not returned in a stack register. */
785 if (aggregate_value_p (DECL_RESULT (decl)))
788 result = DECL_RTL (DECL_RESULT (decl));
789 /* ?!? What is this code supposed to do? Can this code actually
790 trigger if we kick out aggregates above? */
792 && ! (GET_CODE (result) == REG
793 && REGNO (result) < FIRST_PSEUDO_REGISTER))
795 #ifdef FUNCTION_OUTGOING_VALUE
797 = FUNCTION_OUTGOING_VALUE (TREE_TYPE (DECL_RESULT (decl)), decl);
799 result = FUNCTION_VALUE (TREE_TYPE (DECL_RESULT (decl)), decl);
803 return result != 0 && STACK_REG_P (result) ? result : 0;
808 * This section deals with stack register substitution, and forms the second
812 /* Replace REG, which is a pointer to a stack reg RTX, with an RTX for
813 the desired hard REGNO. */
816 replace_reg (reg, regno)
820 if (regno < FIRST_STACK_REG || regno > LAST_STACK_REG
821 || ! STACK_REG_P (*reg))
824 switch (GET_MODE_CLASS (GET_MODE (*reg)))
828 case MODE_COMPLEX_FLOAT:;
831 *reg = FP_MODE_REG (regno, GET_MODE (*reg));
834 /* Remove a note of type NOTE, which must be found, for register
835 number REGNO from INSN. Remove only one such note. */
838 remove_regno_note (insn, note, regno)
843 register rtx *note_link, this;
845 note_link = ®_NOTES(insn);
846 for (this = *note_link; this; this = XEXP (this, 1))
847 if (REG_NOTE_KIND (this) == note
848 && REG_P (XEXP (this, 0)) && REGNO (XEXP (this, 0)) == regno)
850 *note_link = XEXP (this, 1);
854 note_link = &XEXP (this, 1);
859 /* Find the hard register number of virtual register REG in REGSTACK.
860 The hard register number is relative to the top of the stack. -1 is
861 returned if the register is not found. */
864 get_hard_regnum (regstack, reg)
870 if (! STACK_REG_P (reg))
873 for (i = regstack->top; i >= 0; i--)
874 if (regstack->reg[i] == REGNO (reg))
877 return i >= 0 ? (FIRST_STACK_REG + regstack->top - i) : -1;
880 /* Delete INSN from the RTL. Mark the insn, but don't remove it from
881 the chain of insns. Doing so could confuse block_begin and block_end
882 if this were the only insn in the block. */
885 delete_insn_for_stacker (insn)
888 PUT_CODE (insn, NOTE);
889 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
890 NOTE_SOURCE_FILE (insn) = 0;
893 /* Emit an insn to pop virtual register REG before or after INSN.
894 REGSTACK is the stack state after INSN and is updated to reflect this
895 pop. WHEN is either emit_insn_before or emit_insn_after. A pop insn
896 is represented as a SET whose destination is the register to be popped
897 and source is the top of stack. A death note for the top of stack
898 cases the movdf pattern to pop. */
901 emit_pop_insn (insn, regstack, reg, where)
905 enum emit_where where;
907 rtx pop_insn, pop_rtx;
910 hard_regno = get_hard_regnum (regstack, reg);
912 if (hard_regno < FIRST_STACK_REG)
915 pop_rtx = gen_rtx_SET (VOIDmode, FP_MODE_REG (hard_regno, DFmode),
916 FP_MODE_REG (FIRST_STACK_REG, DFmode));
918 if (where == EMIT_AFTER)
919 pop_insn = emit_block_insn_after (pop_rtx, insn, current_block);
921 pop_insn = emit_block_insn_before (pop_rtx, insn, current_block);
924 = gen_rtx_EXPR_LIST (REG_DEAD, FP_MODE_REG (FIRST_STACK_REG, DFmode),
925 REG_NOTES (pop_insn));
927 regstack->reg[regstack->top - (hard_regno - FIRST_STACK_REG)]
928 = regstack->reg[regstack->top];
930 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (reg));
935 /* Emit an insn before or after INSN to swap virtual register REG with
936 the top of stack. REGSTACK is the stack state before the swap, and
937 is updated to reflect the swap. A swap insn is represented as a
938 PARALLEL of two patterns: each pattern moves one reg to the other.
940 If REG is already at the top of the stack, no insn is emitted. */
943 emit_swap_insn (insn, regstack, reg)
950 int tmp, other_reg; /* swap regno temps */
951 rtx i1; /* the stack-reg insn prior to INSN */
952 rtx i1set = NULL_RTX; /* the SET rtx within I1 */
954 hard_regno = get_hard_regnum (regstack, reg);
956 if (hard_regno < FIRST_STACK_REG)
958 if (hard_regno == FIRST_STACK_REG)
961 other_reg = regstack->top - (hard_regno - FIRST_STACK_REG);
963 tmp = regstack->reg[other_reg];
964 regstack->reg[other_reg] = regstack->reg[regstack->top];
965 regstack->reg[regstack->top] = tmp;
967 /* Find the previous insn involving stack regs, but don't pass a
970 if (current_block && insn != current_block->head)
972 rtx tmp = PREV_INSN (insn);
973 while (tmp != current_block->head)
975 if (GET_CODE (tmp) == CODE_LABEL
976 || (GET_CODE (tmp) == NOTE
977 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_BASIC_BLOCK)
978 || (GET_CODE (tmp) == INSN
979 && stack_regs_mentioned (tmp)))
984 tmp = PREV_INSN (tmp);
989 && (i1set = single_set (i1)) != NULL_RTX)
991 rtx i1src = *get_true_reg (&SET_SRC (i1set));
992 rtx i1dest = *get_true_reg (&SET_DEST (i1set));
994 /* If the previous register stack push was from the reg we are to
995 swap with, omit the swap. */
997 if (GET_CODE (i1dest) == REG && REGNO (i1dest) == FIRST_STACK_REG
998 && GET_CODE (i1src) == REG && REGNO (i1src) == hard_regno - 1
999 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
1002 /* If the previous insn wrote to the reg we are to swap with,
1005 if (GET_CODE (i1dest) == REG && REGNO (i1dest) == hard_regno
1006 && GET_CODE (i1src) == REG && REGNO (i1src) == FIRST_STACK_REG
1007 && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
1011 swap_rtx = gen_swapxf (FP_MODE_REG (hard_regno, XFmode),
1012 FP_MODE_REG (FIRST_STACK_REG, XFmode));
1015 emit_block_insn_after (swap_rtx, i1, current_block);
1016 else if (current_block)
1018 i1 = emit_insn_before (swap_rtx, current_block->head);
1019 current_block->head = i1;
1022 emit_insn_before (swap_rtx, insn);
1025 /* Handle a move to or from a stack register in PAT, which is in INSN.
1026 REGSTACK is the current stack. */
1029 move_for_stack_reg (insn, regstack, pat)
1034 rtx *psrc = get_true_reg (&SET_SRC (pat));
1035 rtx *pdest = get_true_reg (&SET_DEST (pat));
1039 src = *psrc; dest = *pdest;
1041 if (STACK_REG_P (src) && STACK_REG_P (dest))
1043 /* Write from one stack reg to another. If SRC dies here, then
1044 just change the register mapping and delete the insn. */
1046 note = find_regno_note (insn, REG_DEAD, REGNO (src));
1051 /* If this is a no-op move, there must not be a REG_DEAD note. */
1052 if (REGNO (src) == REGNO (dest))
1055 for (i = regstack->top; i >= 0; i--)
1056 if (regstack->reg[i] == REGNO (src))
1059 /* The source must be live, and the dest must be dead. */
1060 if (i < 0 || get_hard_regnum (regstack, dest) >= FIRST_STACK_REG)
1063 /* It is possible that the dest is unused after this insn.
1064 If so, just pop the src. */
1066 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
1068 emit_pop_insn (insn, regstack, src, EMIT_AFTER);
1070 delete_insn_for_stacker (insn);
1074 regstack->reg[i] = REGNO (dest);
1076 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1077 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1079 delete_insn_for_stacker (insn);
1084 /* The source reg does not die. */
1086 /* If this appears to be a no-op move, delete it, or else it
1087 will confuse the machine description output patterns. But if
1088 it is REG_UNUSED, we must pop the reg now, as per-insn processing
1089 for REG_UNUSED will not work for deleted insns. */
1091 if (REGNO (src) == REGNO (dest))
1093 if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
1094 emit_pop_insn (insn, regstack, dest, EMIT_AFTER);
1096 delete_insn_for_stacker (insn);
1100 /* The destination ought to be dead */
1101 if (get_hard_regnum (regstack, dest) >= FIRST_STACK_REG)
1104 replace_reg (psrc, get_hard_regnum (regstack, src));
1106 regstack->reg[++regstack->top] = REGNO (dest);
1107 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1108 replace_reg (pdest, FIRST_STACK_REG);
1110 else if (STACK_REG_P (src))
1112 /* Save from a stack reg to MEM, or possibly integer reg. Since
1113 only top of stack may be saved, emit an exchange first if
1116 emit_swap_insn (insn, regstack, src);
1118 note = find_regno_note (insn, REG_DEAD, REGNO (src));
1121 replace_reg (&XEXP (note, 0), FIRST_STACK_REG);
1123 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1125 else if (GET_MODE (src) == XFmode && regstack->top < REG_STACK_SIZE - 1)
1127 /* A 387 cannot write an XFmode value to a MEM without
1128 clobbering the source reg. The output code can handle
1129 this by reading back the value from the MEM.
1130 But it is more efficient to use a temp register if one is
1131 available. Push the source value here if the register
1132 stack is not full, and then write the value to memory via
1134 rtx push_rtx, push_insn;
1135 rtx top_stack_reg = FP_MODE_REG (FIRST_STACK_REG, XFmode);
1137 push_rtx = gen_movxf (top_stack_reg, top_stack_reg);
1138 push_insn = emit_insn_before (push_rtx, insn);
1139 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_DEAD, top_stack_reg,
1143 replace_reg (psrc, FIRST_STACK_REG);
1145 else if (STACK_REG_P (dest))
1147 /* Load from MEM, or possibly integer REG or constant, into the
1148 stack regs. The actual target is always the top of the
1149 stack. The stack mapping is changed to reflect that DEST is
1150 now at top of stack. */
1152 /* The destination ought to be dead */
1153 if (get_hard_regnum (regstack, dest) >= FIRST_STACK_REG)
1156 if (regstack->top >= REG_STACK_SIZE)
1159 regstack->reg[++regstack->top] = REGNO (dest);
1160 SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1161 replace_reg (pdest, FIRST_STACK_REG);
1167 /* Swap the condition on a branch, if there is one. Return true if we
1168 found a condition to swap. False if the condition was not used as
1172 swap_rtx_condition_1 (pat)
1175 register const char *fmt;
1176 register int i, r = 0;
1178 if (GET_RTX_CLASS (GET_CODE (pat)) == '<')
1180 PUT_CODE (pat, swap_condition (GET_CODE (pat)));
1185 fmt = GET_RTX_FORMAT (GET_CODE (pat));
1186 for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
1192 for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
1193 r |= swap_rtx_condition_1 (XVECEXP (pat, i, j));
1195 else if (fmt[i] == 'e')
1196 r |= swap_rtx_condition_1 (XEXP (pat, i));
1204 swap_rtx_condition (insn)
1207 rtx pat = PATTERN (insn);
1209 /* We're looking for a single set to cc0 or an HImode temporary. */
1211 if (GET_CODE (pat) == SET
1212 && GET_CODE (SET_DEST (pat)) == REG
1213 && REGNO (SET_DEST (pat)) == FLAGS_REG)
1215 insn = next_flags_user (insn);
1216 if (insn == NULL_RTX)
1218 pat = PATTERN (insn);
1221 /* See if this is, or ends in, a fnstsw, aka unspec 9. If so, we're
1222 not doing anything with the cc value right now. We may be able to
1223 search for one though. */
1225 if (GET_CODE (pat) == SET
1226 && GET_CODE (SET_SRC (pat)) == UNSPEC
1227 && XINT (SET_SRC (pat), 1) == 9)
1229 rtx dest = SET_DEST (pat);
1231 /* Search forward looking for the first use of this value.
1232 Stop at block boundaries. */
1233 /* ??? This really cries for BLOCK_END! */
1236 insn = NEXT_INSN (insn);
1237 if (insn == NULL_RTX)
1239 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
1240 && reg_mentioned_p (dest, insn))
1242 if (GET_CODE (insn) == JUMP_INSN)
1244 if (GET_CODE (insn) == CODE_LABEL)
1248 /* So we've found the insn using this value. If it is anything
1249 other than sahf, aka unspec 10, or the value does not die
1250 (meaning we'd have to search further), then we must give up. */
1251 pat = PATTERN (insn);
1252 if (GET_CODE (pat) != SET
1253 || GET_CODE (SET_SRC (pat)) != UNSPEC
1254 || XINT (SET_SRC (pat), 1) != 10
1255 || ! dead_or_set_p (insn, dest))
1258 /* Now we are prepared to handle this as a normal cc0 setter. */
1259 insn = next_flags_user (insn);
1260 if (insn == NULL_RTX)
1262 pat = PATTERN (insn);
1265 return swap_rtx_condition_1 (pat);
1268 /* Handle a comparison. Special care needs to be taken to avoid
1269 causing comparisons that a 387 cannot do correctly, such as EQ.
1271 Also, a pop insn may need to be emitted. The 387 does have an
1272 `fcompp' insn that can pop two regs, but it is sometimes too expensive
1273 to do this - a `fcomp' followed by a `fstpl %st(0)' may be easier to
1277 compare_for_stack_reg (insn, regstack, pat_src)
1283 rtx src1_note, src2_note;
1286 src1 = get_true_reg (&XEXP (pat_src, 0));
1287 src2 = get_true_reg (&XEXP (pat_src, 1));
1288 flags_user = next_flags_user (insn);
1290 /* ??? If fxch turns out to be cheaper than fstp, give priority to
1291 registers that die in this insn - move those to stack top first. */
1292 if ((! STACK_REG_P (*src1)
1293 || (STACK_REG_P (*src2)
1294 && get_hard_regnum (regstack, *src2) == FIRST_STACK_REG))
1295 && swap_rtx_condition (insn))
1298 temp = XEXP (pat_src, 0);
1299 XEXP (pat_src, 0) = XEXP (pat_src, 1);
1300 XEXP (pat_src, 1) = temp;
1302 src1 = get_true_reg (&XEXP (pat_src, 0));
1303 src2 = get_true_reg (&XEXP (pat_src, 1));
1305 INSN_CODE (insn) = -1;
1308 /* We will fix any death note later. */
1310 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1312 if (STACK_REG_P (*src2))
1313 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1315 src2_note = NULL_RTX;
1317 emit_swap_insn (insn, regstack, *src1);
1319 replace_reg (src1, FIRST_STACK_REG);
1321 if (STACK_REG_P (*src2))
1322 replace_reg (src2, get_hard_regnum (regstack, *src2));
1326 pop_stack (regstack, REGNO (XEXP (src1_note, 0)));
1327 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1330 /* If the second operand dies, handle that. But if the operands are
1331 the same stack register, don't bother, because only one death is
1332 needed, and it was just handled. */
1335 && ! (STACK_REG_P (*src1) && STACK_REG_P (*src2)
1336 && REGNO (*src1) == REGNO (*src2)))
1338 /* As a special case, two regs may die in this insn if src2 is
1339 next to top of stack and the top of stack also dies. Since
1340 we have already popped src1, "next to top of stack" is really
1341 at top (FIRST_STACK_REG) now. */
1343 if (get_hard_regnum (regstack, XEXP (src2_note, 0)) == FIRST_STACK_REG
1346 pop_stack (regstack, REGNO (XEXP (src2_note, 0)));
1347 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1351 /* The 386 can only represent death of the first operand in
1352 the case handled above. In all other cases, emit a separate
1353 pop and remove the death note from here. */
1355 /* link_cc0_insns (insn); */
1357 remove_regno_note (insn, REG_DEAD, REGNO (XEXP (src2_note, 0)));
1359 emit_pop_insn (insn, regstack, XEXP (src2_note, 0),
1365 /* Substitute new registers in PAT, which is part of INSN. REGSTACK
1366 is the current register layout. */
1369 subst_stack_regs_pat (insn, regstack, pat)
1376 switch (GET_CODE (pat))
1379 /* Deaths in USE insns can happen in non optimizing compilation.
1380 Handle them by popping the dying register. */
1381 src = get_true_reg (&XEXP (pat, 0));
1382 if (STACK_REG_P (*src)
1383 && find_regno_note (insn, REG_DEAD, REGNO (*src)))
1385 emit_pop_insn (insn, regstack, *src, EMIT_AFTER);
1388 /* ??? Uninitialized USE should not happen. */
1389 else if (get_hard_regnum (regstack, *src) == -1)
1397 dest = get_true_reg (&XEXP (pat, 0));
1398 if (STACK_REG_P (*dest))
1400 note = find_reg_note (insn, REG_DEAD, *dest);
1402 if (pat != PATTERN (insn))
1404 /* The fix_truncdi_1 pattern wants to be able to allocate
1405 it's own scratch register. It does this by clobbering
1406 an fp reg so that it is assured of an empty reg-stack
1407 register. If the register is live, kill it now.
1408 Remove the DEAD/UNUSED note so we don't try to kill it
1412 emit_pop_insn (insn, regstack, *dest, EMIT_BEFORE);
1415 note = find_reg_note (insn, REG_UNUSED, *dest);
1419 remove_note (insn, note);
1420 replace_reg (dest, LAST_STACK_REG);
1424 /* A top-level clobber with no REG_DEAD, and no hard-regnum
1425 indicates an uninitialized value. Because reload removed
1426 all other clobbers, this must be due to a function
1427 returning without a value. Load up a NaN. */
1430 && get_hard_regnum (regstack, *dest) == -1)
1432 pat = gen_rtx_SET (VOIDmode,
1433 FP_MODE_REG (REGNO (*dest), SFmode),
1435 PATTERN (insn) = pat;
1436 move_for_stack_reg (insn, regstack, pat);
1445 rtx *src1 = (rtx *) NULL_PTR, *src2;
1446 rtx src1_note, src2_note;
1449 dest = get_true_reg (&SET_DEST (pat));
1450 src = get_true_reg (&SET_SRC (pat));
1451 pat_src = SET_SRC (pat);
1453 /* See if this is a `movM' pattern, and handle elsewhere if so. */
1454 if (STACK_REG_P (*src)
1455 || (STACK_REG_P (*dest)
1456 && (GET_CODE (*src) == REG || GET_CODE (*src) == MEM
1457 || GET_CODE (*src) == CONST_DOUBLE)))
1459 move_for_stack_reg (insn, regstack, pat);
1463 switch (GET_CODE (pat_src))
1466 compare_for_stack_reg (insn, regstack, pat_src);
1472 for (count = HARD_REGNO_NREGS (REGNO (*dest), GET_MODE (*dest));
1475 regstack->reg[++regstack->top] = REGNO (*dest) + count;
1476 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest) + count);
1479 replace_reg (dest, FIRST_STACK_REG);
1483 /* This is a `tstM2' case. */
1484 if (*dest != cc0_rtx)
1490 case FLOAT_TRUNCATE:
1494 /* These insns only operate on the top of the stack. DEST might
1495 be cc0_rtx if we're processing a tstM pattern. Also, it's
1496 possible that the tstM case results in a REG_DEAD note on the
1500 src1 = get_true_reg (&XEXP (pat_src, 0));
1502 emit_swap_insn (insn, regstack, *src1);
1504 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1506 if (STACK_REG_P (*dest))
1507 replace_reg (dest, FIRST_STACK_REG);
1511 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1513 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1516 replace_reg (src1, FIRST_STACK_REG);
1521 /* On i386, reversed forms of subM3 and divM3 exist for
1522 MODE_FLOAT, so the same code that works for addM3 and mulM3
1526 /* These insns can accept the top of stack as a destination
1527 from a stack reg or mem, or can use the top of stack as a
1528 source and some other stack register (possibly top of stack)
1529 as a destination. */
1531 src1 = get_true_reg (&XEXP (pat_src, 0));
1532 src2 = get_true_reg (&XEXP (pat_src, 1));
1534 /* We will fix any death note later. */
1536 if (STACK_REG_P (*src1))
1537 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1539 src1_note = NULL_RTX;
1540 if (STACK_REG_P (*src2))
1541 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1543 src2_note = NULL_RTX;
1545 /* If either operand is not a stack register, then the dest
1546 must be top of stack. */
1548 if (! STACK_REG_P (*src1) || ! STACK_REG_P (*src2))
1549 emit_swap_insn (insn, regstack, *dest);
1552 /* Both operands are REG. If neither operand is already
1553 at the top of stack, choose to make the one that is the dest
1554 the new top of stack. */
1556 int src1_hard_regnum, src2_hard_regnum;
1558 src1_hard_regnum = get_hard_regnum (regstack, *src1);
1559 src2_hard_regnum = get_hard_regnum (regstack, *src2);
1560 if (src1_hard_regnum == -1 || src2_hard_regnum == -1)
1563 if (src1_hard_regnum != FIRST_STACK_REG
1564 && src2_hard_regnum != FIRST_STACK_REG)
1565 emit_swap_insn (insn, regstack, *dest);
1568 if (STACK_REG_P (*src1))
1569 replace_reg (src1, get_hard_regnum (regstack, *src1));
1570 if (STACK_REG_P (*src2))
1571 replace_reg (src2, get_hard_regnum (regstack, *src2));
1575 rtx src1_reg = XEXP (src1_note, 0);
1577 /* If the register that dies is at the top of stack, then
1578 the destination is somewhere else - merely substitute it.
1579 But if the reg that dies is not at top of stack, then
1580 move the top of stack to the dead reg, as though we had
1581 done the insn and then a store-with-pop. */
1583 if (REGNO (src1_reg) == regstack->reg[regstack->top])
1585 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1586 replace_reg (dest, get_hard_regnum (regstack, *dest));
1590 int regno = get_hard_regnum (regstack, src1_reg);
1592 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1593 replace_reg (dest, regno);
1595 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1596 = regstack->reg[regstack->top];
1599 CLEAR_HARD_REG_BIT (regstack->reg_set,
1600 REGNO (XEXP (src1_note, 0)));
1601 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1606 rtx src2_reg = XEXP (src2_note, 0);
1607 if (REGNO (src2_reg) == regstack->reg[regstack->top])
1609 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1610 replace_reg (dest, get_hard_regnum (regstack, *dest));
1614 int regno = get_hard_regnum (regstack, src2_reg);
1616 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1617 replace_reg (dest, regno);
1619 regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1620 = regstack->reg[regstack->top];
1623 CLEAR_HARD_REG_BIT (regstack->reg_set,
1624 REGNO (XEXP (src2_note, 0)));
1625 replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG);
1630 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1631 replace_reg (dest, get_hard_regnum (regstack, *dest));
1636 switch (XINT (pat_src, 1))
1640 /* These insns only operate on the top of the stack. */
1642 src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1644 emit_swap_insn (insn, regstack, *src1);
1646 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1648 if (STACK_REG_P (*dest))
1649 replace_reg (dest, FIRST_STACK_REG);
1653 replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1655 CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1658 replace_reg (src1, FIRST_STACK_REG);
1662 /* (unspec [(unspec [(compare ..)] 9)] 10)
1663 Unspec 9 is fnstsw; unspec 10 is sahf. The combination
1664 matches the PPRO fcomi instruction. */
1666 pat_src = XVECEXP (pat_src, 0, 0);
1667 if (GET_CODE (pat_src) != UNSPEC
1668 || XINT (pat_src, 1) != 9)
1673 /* (unspec [(compare ..)] 9) */
1674 /* Combined fcomp+fnstsw generated for doing well with
1675 CSE. When optimizing this would have been broken
1678 pat_src = XVECEXP (pat_src, 0, 0);
1679 if (GET_CODE (pat_src) != COMPARE)
1682 compare_for_stack_reg (insn, regstack, pat_src);
1691 /* This insn requires the top of stack to be the destination. */
1693 /* If the comparison operator is an FP comparison operator,
1694 it is handled correctly by compare_for_stack_reg () who
1695 will move the destination to the top of stack. But if the
1696 comparison operator is not an FP comparison operator, we
1697 have to handle it here. */
1698 if (get_hard_regnum (regstack, *dest) >= FIRST_STACK_REG
1699 && REGNO (*dest) != regstack->reg[regstack->top])
1700 emit_swap_insn (insn, regstack, *dest);
1702 src1 = get_true_reg (&XEXP (pat_src, 1));
1703 src2 = get_true_reg (&XEXP (pat_src, 2));
1705 src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1706 src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1713 src_note[1] = src1_note;
1714 src_note[2] = src2_note;
1716 if (STACK_REG_P (*src1))
1717 replace_reg (src1, get_hard_regnum (regstack, *src1));
1718 if (STACK_REG_P (*src2))
1719 replace_reg (src2, get_hard_regnum (regstack, *src2));
1721 for (i = 1; i <= 2; i++)
1724 int regno = REGNO (XEXP (src_note[i], 0));
1726 /* If the register that dies is not at the top of
1727 stack, then move the top of stack to the dead reg */
1728 if (regno != regstack->reg[regstack->top])
1730 remove_regno_note (insn, REG_DEAD, regno);
1731 emit_pop_insn (insn, regstack, XEXP (src_note[i], 0),
1736 CLEAR_HARD_REG_BIT (regstack->reg_set, regno);
1737 replace_reg (&XEXP (src_note[i], 0), FIRST_STACK_REG);
1743 /* Make dest the top of stack. Add dest to regstack if
1745 if (get_hard_regnum (regstack, *dest) < FIRST_STACK_REG)
1746 regstack->reg[++regstack->top] = REGNO (*dest);
1747 SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1748 replace_reg (dest, FIRST_STACK_REG);
1762 /* Substitute hard regnums for any stack regs in INSN, which has
1763 N_INPUTS inputs and N_OUTPUTS outputs. REGSTACK is the stack info
1764 before the insn, and is updated with changes made here.
1766 There are several requirements and assumptions about the use of
1767 stack-like regs in asm statements. These rules are enforced by
1768 record_asm_stack_regs; see comments there for details. Any
1769 asm_operands left in the RTL at this point may be assume to meet the
1770 requirements, since record_asm_stack_regs removes any problem asm. */
1773 subst_asm_stack_regs (insn, regstack)
1777 rtx body = PATTERN (insn);
1780 rtx *note_reg; /* Array of note contents */
1781 rtx **note_loc; /* Address of REG field of each note */
1782 enum reg_note *note_kind; /* The type of each note */
1787 struct stack_def temp_stack;
1792 int n_inputs, n_outputs;
1794 if (! check_asm_stack_operands (insn))
1797 /* Find out what the constraints required. If no constraint
1798 alternative matches, that is a compiler bug: we should have caught
1799 such an insn in check_asm_stack_operands. */
1800 extract_insn (insn);
1801 constrain_operands (1);
1802 alt = which_alternative;
1804 preprocess_constraints ();
1806 n_inputs = get_asm_operand_n_inputs (body);
1807 n_outputs = recog_data.n_operands - n_inputs;
1812 /* Strip SUBREGs here to make the following code simpler. */
1813 for (i = 0; i < recog_data.n_operands; i++)
1814 if (GET_CODE (recog_data.operand[i]) == SUBREG
1815 && GET_CODE (SUBREG_REG (recog_data.operand[i])) == REG)
1817 recog_data.operand_loc[i] = & SUBREG_REG (recog_data.operand[i]);
1818 recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
1821 /* Set up NOTE_REG, NOTE_LOC and NOTE_KIND. */
1823 for (i = 0, note = REG_NOTES (insn); note; note = XEXP (note, 1))
1826 note_reg = (rtx *) alloca (i * sizeof (rtx));
1827 note_loc = (rtx **) alloca (i * sizeof (rtx *));
1828 note_kind = (enum reg_note *) alloca (i * sizeof (enum reg_note));
1831 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
1833 rtx reg = XEXP (note, 0);
1834 rtx *loc = & XEXP (note, 0);
1836 if (GET_CODE (reg) == SUBREG && GET_CODE (SUBREG_REG (reg)) == REG)
1838 loc = & SUBREG_REG (reg);
1839 reg = SUBREG_REG (reg);
1842 if (STACK_REG_P (reg)
1843 && (REG_NOTE_KIND (note) == REG_DEAD
1844 || REG_NOTE_KIND (note) == REG_UNUSED))
1846 note_reg[n_notes] = reg;
1847 note_loc[n_notes] = loc;
1848 note_kind[n_notes] = REG_NOTE_KIND (note);
1853 /* Set up CLOBBER_REG and CLOBBER_LOC. */
1857 if (GET_CODE (body) == PARALLEL)
1859 clobber_reg = (rtx *) alloca (XVECLEN (body, 0) * sizeof (rtx));
1860 clobber_loc = (rtx **) alloca (XVECLEN (body, 0) * sizeof (rtx *));
1862 for (i = 0; i < XVECLEN (body, 0); i++)
1863 if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
1865 rtx clobber = XVECEXP (body, 0, i);
1866 rtx reg = XEXP (clobber, 0);
1867 rtx *loc = & XEXP (clobber, 0);
1869 if (GET_CODE (reg) == SUBREG && GET_CODE (SUBREG_REG (reg)) == REG)
1871 loc = & SUBREG_REG (reg);
1872 reg = SUBREG_REG (reg);
1875 if (STACK_REG_P (reg))
1877 clobber_reg[n_clobbers] = reg;
1878 clobber_loc[n_clobbers] = loc;
1884 temp_stack = *regstack;
1886 /* Put the input regs into the desired place in TEMP_STACK. */
1888 for (i = n_outputs; i < n_outputs + n_inputs; i++)
1889 if (STACK_REG_P (recog_data.operand[i])
1890 && reg_class_subset_p (recog_op_alt[i][alt].class,
1892 && recog_op_alt[i][alt].class != FLOAT_REGS)
1894 /* If an operand needs to be in a particular reg in
1895 FLOAT_REGS, the constraint was either 't' or 'u'. Since
1896 these constraints are for single register classes, and
1897 reload guaranteed that operand[i] is already in that class,
1898 we can just use REGNO (recog_data.operand[i]) to know which
1899 actual reg this operand needs to be in. */
1901 int regno = get_hard_regnum (&temp_stack, recog_data.operand[i]);
1906 if (regno != REGNO (recog_data.operand[i]))
1908 /* recog_data.operand[i] is not in the right place. Find
1909 it and swap it with whatever is already in I's place.
1910 K is where recog_data.operand[i] is now. J is where it
1914 k = temp_stack.top - (regno - FIRST_STACK_REG);
1916 - (REGNO (recog_data.operand[i]) - FIRST_STACK_REG));
1918 temp = temp_stack.reg[k];
1919 temp_stack.reg[k] = temp_stack.reg[j];
1920 temp_stack.reg[j] = temp;
1924 /* Emit insns before INSN to make sure the reg-stack is in the right
1927 change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
1929 /* Make the needed input register substitutions. Do death notes and
1930 clobbers too, because these are for inputs, not outputs. */
1932 for (i = n_outputs; i < n_outputs + n_inputs; i++)
1933 if (STACK_REG_P (recog_data.operand[i]))
1935 int regnum = get_hard_regnum (regstack, recog_data.operand[i]);
1940 replace_reg (recog_data.operand_loc[i], regnum);
1943 for (i = 0; i < n_notes; i++)
1944 if (note_kind[i] == REG_DEAD)
1946 int regnum = get_hard_regnum (regstack, note_reg[i]);
1951 replace_reg (note_loc[i], regnum);
1954 for (i = 0; i < n_clobbers; i++)
1956 /* It's OK for a CLOBBER to reference a reg that is not live.
1957 Don't try to replace it in that case. */
1958 int regnum = get_hard_regnum (regstack, clobber_reg[i]);
1962 /* Sigh - clobbers always have QImode. But replace_reg knows
1963 that these regs can't be MODE_INT and will abort. Just put
1964 the right reg there without calling replace_reg. */
1966 *clobber_loc[i] = FP_MODE_REG (regnum, DFmode);
1970 /* Now remove from REGSTACK any inputs that the asm implicitly popped. */
1972 for (i = n_outputs; i < n_outputs + n_inputs; i++)
1973 if (STACK_REG_P (recog_data.operand[i]))
1975 /* An input reg is implicitly popped if it is tied to an
1976 output, or if there is a CLOBBER for it. */
1979 for (j = 0; j < n_clobbers; j++)
1980 if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
1983 if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
1985 /* recog_data.operand[i] might not be at the top of stack.
1986 But that's OK, because all we need to do is pop the
1987 right number of regs off of the top of the reg-stack.
1988 record_asm_stack_regs guaranteed that all implicitly
1989 popped regs were grouped at the top of the reg-stack. */
1991 CLEAR_HARD_REG_BIT (regstack->reg_set,
1992 regstack->reg[regstack->top]);
1997 /* Now add to REGSTACK any outputs that the asm implicitly pushed.
1998 Note that there isn't any need to substitute register numbers.
1999 ??? Explain why this is true. */
2001 for (i = LAST_STACK_REG; i >= FIRST_STACK_REG; i--)
2003 /* See if there is an output for this hard reg. */
2006 for (j = 0; j < n_outputs; j++)
2007 if (STACK_REG_P (recog_data.operand[j])
2008 && REGNO (recog_data.operand[j]) == i)
2010 regstack->reg[++regstack->top] = i;
2011 SET_HARD_REG_BIT (regstack->reg_set, i);
2016 /* Now emit a pop insn for any REG_UNUSED output, or any REG_DEAD
2017 input that the asm didn't implicitly pop. If the asm didn't
2018 implicitly pop an input reg, that reg will still be live.
2020 Note that we can't use find_regno_note here: the register numbers
2021 in the death notes have already been substituted. */
2023 for (i = 0; i < n_outputs; i++)
2024 if (STACK_REG_P (recog_data.operand[i]))
2028 for (j = 0; j < n_notes; j++)
2029 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2030 && note_kind[j] == REG_UNUSED)
2032 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2038 for (i = n_outputs; i < n_outputs + n_inputs; i++)
2039 if (STACK_REG_P (recog_data.operand[i]))
2043 for (j = 0; j < n_notes; j++)
2044 if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2045 && note_kind[j] == REG_DEAD
2046 && TEST_HARD_REG_BIT (regstack->reg_set,
2047 REGNO (recog_data.operand[i])))
2049 insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2056 /* Substitute stack hard reg numbers for stack virtual registers in
2057 INSN. Non-stack register numbers are not changed. REGSTACK is the
2058 current stack content. Insns may be emitted as needed to arrange the
2059 stack for the 387 based on the contents of the insn. */
2062 subst_stack_regs (insn, regstack)
2066 register rtx *note_link, note;
2069 if (GET_CODE (insn) == CALL_INSN)
2071 int top = regstack->top;
2073 /* If there are any floating point parameters to be passed in
2074 registers for this call, make sure they are in the right
2079 straighten_stack (PREV_INSN (insn), regstack);
2081 /* Now mark the arguments as dead after the call. */
2083 while (regstack->top >= 0)
2085 CLEAR_HARD_REG_BIT (regstack->reg_set, FIRST_STACK_REG + regstack->top);
2091 /* Do the actual substitution if any stack regs are mentioned.
2092 Since we only record whether entire insn mentions stack regs, and
2093 subst_stack_regs_pat only works for patterns that contain stack regs,
2094 we must check each pattern in a parallel here. A call_value_pop could
2097 if (stack_regs_mentioned (insn))
2099 int n_operands = asm_noperands (PATTERN (insn));
2100 if (n_operands >= 0)
2102 /* This insn is an `asm' with operands. Decode the operands,
2103 decide how many are inputs, and do register substitution.
2104 Any REG_UNUSED notes will be handled by subst_asm_stack_regs. */
2106 subst_asm_stack_regs (insn, regstack);
2110 if (GET_CODE (PATTERN (insn)) == PARALLEL)
2111 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
2113 if (stack_regs_mentioned_p (XVECEXP (PATTERN (insn), 0, i)))
2114 subst_stack_regs_pat (insn, regstack,
2115 XVECEXP (PATTERN (insn), 0, i));
2118 subst_stack_regs_pat (insn, regstack, PATTERN (insn));
2121 /* subst_stack_regs_pat may have deleted a no-op insn. If so, any
2122 REG_UNUSED will already have been dealt with, so just return. */
2124 if (GET_CODE (insn) == NOTE)
2127 /* If there is a REG_UNUSED note on a stack register on this insn,
2128 the indicated reg must be popped. The REG_UNUSED note is removed,
2129 since the form of the newly emitted pop insn references the reg,
2130 making it no longer `unset'. */
2132 note_link = ®_NOTES(insn);
2133 for (note = *note_link; note; note = XEXP (note, 1))
2134 if (REG_NOTE_KIND (note) == REG_UNUSED && STACK_REG_P (XEXP (note, 0)))
2136 *note_link = XEXP (note, 1);
2137 insn = emit_pop_insn (insn, regstack, XEXP (note, 0), EMIT_AFTER);
2140 note_link = &XEXP (note, 1);
2143 /* Change the organization of the stack so that it fits a new basic
2144 block. Some registers might have to be popped, but there can never be
2145 a register live in the new block that is not now live.
2147 Insert any needed insns before or after INSN, as indicated by
2148 WHERE. OLD is the original stack layout, and NEW is the desired
2149 form. OLD is updated to reflect the code emitted, ie, it will be
2150 the same as NEW upon return.
2152 This function will not preserve block_end[]. But that information
2153 is no longer needed once this has executed. */
2156 change_stack (insn, old, new, where)
2160 enum emit_where where;
2165 /* We will be inserting new insns "backwards". If we are to insert
2166 after INSN, find the next insn, and insert before it. */
2168 if (where == EMIT_AFTER)
2170 if (current_block && current_block->end == insn)
2172 insn = NEXT_INSN (insn);
2175 /* Pop any registers that are not needed in the new block. */
2177 for (reg = old->top; reg >= 0; reg--)
2178 if (! TEST_HARD_REG_BIT (new->reg_set, old->reg[reg]))
2179 emit_pop_insn (insn, old, FP_MODE_REG (old->reg[reg], DFmode),
2184 /* If the new block has never been processed, then it can inherit
2185 the old stack order. */
2187 new->top = old->top;
2188 memcpy (new->reg, old->reg, sizeof (new->reg));
2192 /* This block has been entered before, and we must match the
2193 previously selected stack order. */
2195 /* By now, the only difference should be the order of the stack,
2196 not their depth or liveliness. */
2198 GO_IF_HARD_REG_EQUAL (old->reg_set, new->reg_set, win);
2201 if (old->top != new->top)
2204 /* If the stack is not empty (new->top != -1), loop here emitting
2205 swaps until the stack is correct.
2207 The worst case number of swaps emitted is N + 2, where N is the
2208 depth of the stack. In some cases, the reg at the top of
2209 stack may be correct, but swapped anyway in order to fix
2210 other regs. But since we never swap any other reg away from
2211 its correct slot, this algorithm will converge. */
2216 /* Swap the reg at top of stack into the position it is
2217 supposed to be in, until the correct top of stack appears. */
2219 while (old->reg[old->top] != new->reg[new->top])
2221 for (reg = new->top; reg >= 0; reg--)
2222 if (new->reg[reg] == old->reg[old->top])
2228 emit_swap_insn (insn, old,
2229 FP_MODE_REG (old->reg[reg], DFmode));
2232 /* See if any regs remain incorrect. If so, bring an
2233 incorrect reg to the top of stack, and let the while loop
2236 for (reg = new->top; reg >= 0; reg--)
2237 if (new->reg[reg] != old->reg[reg])
2239 emit_swap_insn (insn, old,
2240 FP_MODE_REG (old->reg[reg], DFmode));
2245 /* At this point there must be no differences. */
2247 for (reg = old->top; reg >= 0; reg--)
2248 if (old->reg[reg] != new->reg[reg])
2253 current_block->end = PREV_INSN (insn);
2256 /* Print stack configuration. */
2259 print_stack (file, s)
2267 fprintf (file, "uninitialized\n");
2268 else if (s->top == -1)
2269 fprintf (file, "empty\n");
2274 for (i = 0; i <= s->top; ++i)
2275 fprintf (file, "%d ", s->reg[i]);
2276 fputs ("]\n", file);
2280 /* This function was doing life analysis. We now let the regular live
2281 code do it's job, so we only need to check some extra invariants
2282 that reg-stack expects. Primary among these being that all registers
2283 are initialized before use.
2285 The function returns true when code was emitted to CFG edges and
2286 commit_edge_insertions needs to be called. */
2289 convert_regs_entry ()
2291 int inserted = 0, i;
2294 for (i = n_basic_blocks - 1; i >= 0; --i)
2296 basic_block block = BASIC_BLOCK (i);
2297 block_info bi = BLOCK_INFO (block);
2300 /* Set current register status at last instruction `uninitialized'. */
2301 bi->stack_in.top = -2;
2303 /* Copy live_at_end and live_at_start into temporaries. */
2304 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; reg++)
2306 if (REGNO_REG_SET_P (block->global_live_at_end, reg))
2307 SET_HARD_REG_BIT (bi->out_reg_set, reg);
2308 if (REGNO_REG_SET_P (block->global_live_at_start, reg))
2309 SET_HARD_REG_BIT (bi->stack_in.reg_set, reg);
2313 /* Load something into each stack register live at function entry.
2314 Such live registers can be caused by uninitialized variables or
2315 functions not returning values on all paths. In order to keep
2316 the push/pop code happy, and to not scrog the register stack, we
2317 must put something in these registers. Use a QNaN.
2319 Note that we are insertting converted code here. This code is
2320 never seen by the convert_regs pass. */
2322 for (e = ENTRY_BLOCK_PTR->succ; e ; e = e->succ_next)
2324 basic_block block = e->dest;
2325 block_info bi = BLOCK_INFO (block);
2328 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2329 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2333 bi->stack_in.reg[++top] = reg;
2335 init = gen_rtx_SET (VOIDmode,
2336 FP_MODE_REG (FIRST_STACK_REG, SFmode),
2338 insert_insn_on_edge (init, e);
2342 bi->stack_in.top = top;
2348 /* Construct the desired stack for function exit. This will either
2349 be `empty', or the function return value at top-of-stack. */
2352 convert_regs_exit ()
2354 int value_reg_low, value_reg_high;
2358 retvalue = stack_result (current_function_decl);
2359 value_reg_low = value_reg_high = -1;
2362 value_reg_low = REGNO (retvalue);
2363 value_reg_high = value_reg_low
2364 + HARD_REGNO_NREGS (value_reg_low, GET_MODE (retvalue)) - 1;
2367 output_stack = &BLOCK_INFO (EXIT_BLOCK_PTR)->stack_in;
2368 if (value_reg_low == -1)
2369 output_stack->top = -1;
2374 output_stack->top = value_reg_high - value_reg_low;
2375 for (reg = value_reg_low; reg <= value_reg_high; ++reg)
2377 output_stack->reg[reg - value_reg_low] = reg;
2378 SET_HARD_REG_BIT (output_stack->reg_set, reg);
2383 /* Convert stack register references in one block. */
2386 convert_regs_1 (file, block)
2390 struct stack_def regstack, tmpstack;
2391 block_info bi = BLOCK_INFO (block);
2396 current_block = block;
2400 fprintf (file, "\nBasic block %d\nInput stack: ", block->index);
2401 print_stack (file, &bi->stack_in);
2404 /* Process all insns in this block. Keep track of NEXT so that we
2405 don't process insns emitted while substituting in INSN. */
2407 regstack = bi->stack_in;
2411 next = NEXT_INSN (insn);
2413 /* Ensure we have not missed a block boundary. */
2416 if (insn == block->end)
2419 /* Don't bother processing unless there is a stack reg
2420 mentioned or if it's a CALL_INSN. */
2421 if (stack_regs_mentioned (insn)
2422 || GET_CODE (insn) == CALL_INSN)
2426 fprintf (file, " insn %d input stack: ",
2428 print_stack (file, ®stack);
2430 subst_stack_regs (insn, ®stack);
2437 fprintf (file, "Expected live registers [");
2438 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2439 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg))
2440 fprintf (file, " %d", reg);
2441 fprintf (file, " ]\nOutput stack: ");
2442 print_stack (file, ®stack);
2446 if (GET_CODE (insn) == JUMP_INSN)
2447 insn = PREV_INSN (insn);
2449 /* If the function is declared to return a value, but it returns one
2450 in only some cases, some registers might come live here. Emit
2451 necessary moves for them. */
2453 for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2455 if (TEST_HARD_REG_BIT (bi->out_reg_set, reg)
2456 && ! TEST_HARD_REG_BIT (regstack.reg_set, reg))
2462 fprintf (file, "Emitting insn initializing reg %d\n",
2466 set = gen_rtx_SET (VOIDmode, FP_MODE_REG (reg, SFmode),
2468 insn = emit_block_insn_after (set, insn, block);
2469 subst_stack_regs (insn, ®stack);
2473 /* Something failed if the stack lives don't match. */
2474 GO_IF_HARD_REG_EQUAL (regstack.reg_set, bi->out_reg_set, win);
2478 /* Adjust the stack of this block on exit to match the stack of the
2479 target block, or copy stack info into the stack of the successor
2480 of the successor hasn't been processed yet. */
2482 for (e = block->succ; e ; e = e->succ_next)
2484 basic_block target = e->dest;
2485 stack target_stack = &BLOCK_INFO (target)->stack_in;
2488 fprintf (file, "Edge to block %d: ", target->index);
2490 if (target_stack->top == -2)
2492 /* The target block hasn't had a stack order selected.
2493 We need merely ensure that no pops are needed. */
2494 for (reg = regstack.top; reg >= 0; --reg)
2495 if (! TEST_HARD_REG_BIT (target_stack->reg_set,
2502 fprintf (file, "new block; copying stack position\n");
2504 /* change_stack kills values in regstack. */
2505 tmpstack = regstack;
2507 change_stack (block->end, &tmpstack,
2508 target_stack, EMIT_AFTER);
2513 fprintf (file, "new block; pops needed\n");
2517 if (target_stack->top == regstack.top)
2519 for (reg = target_stack->top; reg >= 0; --reg)
2520 if (target_stack->reg[reg] != regstack.reg[reg])
2526 fprintf (file, "no changes needed\n");
2533 fprintf (file, "correcting stack to ");
2534 print_stack (file, target_stack);
2538 /* Care for EH edges specially. The normal return path may return
2539 a value in st(0), but the EH path will not, and there's no need
2540 to add popping code to the edge. */
2541 if (e->flags & EDGE_EH)
2543 /* Assert that the lifetimes are as we expect -- one value
2544 live at st(0) on the end of the source block, and no
2545 values live at the beginning of the destination block. */
2548 CLEAR_HARD_REG_SET (tmp);
2549 GO_IF_HARD_REG_EQUAL (target_stack->reg_set, tmp, eh1);
2553 SET_HARD_REG_BIT (tmp, FIRST_STACK_REG);
2554 GO_IF_HARD_REG_EQUAL (regstack.reg_set, tmp, eh2);
2558 target_stack->top = -1;
2561 /* It is better to output directly to the end of the block
2562 instead of to the edge, because emit_swap can do minimal
2563 insn scheduling. We can do this when there is only one
2564 edge out, and it is not abnormal. */
2565 else if (block->succ->succ_next == NULL
2566 && ! (e->flags & EDGE_ABNORMAL))
2568 /* change_stack kills values in regstack. */
2569 tmpstack = regstack;
2571 change_stack (block->end, &tmpstack, target_stack,
2572 (GET_CODE (block->end) == JUMP_INSN
2573 ? EMIT_BEFORE : EMIT_AFTER));
2579 /* We don't support abnormal edges. Global takes care to
2580 avoid any live register across them, so we should never
2581 have to insert instructions on such edges. */
2582 if (e->flags & EDGE_ABNORMAL)
2585 current_block = NULL;
2588 /* ??? change_stack needs some point to emit insns after.
2589 Also needed to keep gen_sequence from returning a
2590 pattern as opposed to a sequence, which would lose
2592 after = emit_note (NULL, NOTE_INSN_DELETED);
2594 tmpstack = regstack;
2595 change_stack (after, &tmpstack, target_stack, EMIT_BEFORE);
2597 seq = gen_sequence ();
2600 insert_insn_on_edge (seq, e);
2602 current_block = block;
2609 /* Convert registers in all blocks reachable from BLOCK. */
2612 convert_regs_2 (file, block)
2616 basic_block *stack, *sp;
2619 stack = (basic_block *) alloca (sizeof (*stack) * n_basic_blocks);
2623 BLOCK_INFO (block)->done = 1;
2631 inserted |= convert_regs_1 (file, block);
2633 for (e = block->succ; e ; e = e->succ_next)
2634 if (! BLOCK_INFO (e->dest)->done)
2637 BLOCK_INFO (e->dest)->done = 1;
2640 while (sp != stack);
2645 /* Traverse all basic blocks in a function, converting the register
2646 references in each insn from the "flat" register file that gcc uses,
2647 to the stack-like registers the 387 uses. */
2656 /* Initialize uninitialized registers on function entry. */
2657 inserted = convert_regs_entry ();
2659 /* Construct the desired stack for function exit. */
2660 convert_regs_exit ();
2661 BLOCK_INFO (EXIT_BLOCK_PTR)->done = 1;
2663 /* ??? Future: process inner loops first, and give them arbitrary
2664 initial stacks which emit_swap_insn can modify. This ought to
2665 prevent double fxch that aften appears at the head of a loop. */
2667 /* Process all blocks reachable from all entry points. */
2668 for (e = ENTRY_BLOCK_PTR->succ; e ; e = e->succ_next)
2669 inserted |= convert_regs_2 (file, e->dest);
2671 /* ??? Process all unreachable blocks. Though there's no excuse
2672 for keeping these even when not optimizing. */
2673 for (i = 0; i < n_basic_blocks; ++i)
2675 basic_block b = BASIC_BLOCK (i);
2676 block_info bi = BLOCK_INFO (b);
2682 /* Create an arbitrary input stack. */
2683 bi->stack_in.top = -1;
2684 for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2685 if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2686 bi->stack_in.reg[++bi->stack_in.top] = reg;
2688 inserted |= convert_regs_2 (file, b);
2693 commit_edge_insertions ();
2700 #endif /* STACK_REGS */