1 /* Register to Stack convert for GNU compiler.
2 Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This pass converts stack-like registers from the "flat register
23 file" model that gcc uses, to a stack convention that the 387 uses.
25 * The form of the input:
27 On input, the function consists of insn that have had their
28 registers fully allocated to a set of "virtual" registers. Note that
29 the word "virtual" is used differently here than elsewhere in gcc: for
30 each virtual stack reg, there is a hard reg, but the mapping between
31 them is not known until this pass is run. On output, hard register
32 numbers have been substituted, and various pop and exchange insns have
33 been emitted. The hard register numbers and the virtual register
34 numbers completely overlap - before this pass, all stack register
35 numbers are virtual, and afterward they are all hard.
37 The virtual registers can be manipulated normally by gcc, and their
38 semantics are the same as for normal registers. After the hard
39 register numbers are substituted, the semantics of an insn containing
40 stack-like regs are not the same as for an insn with normal regs: for
41 instance, it is not safe to delete an insn that appears to be a no-op
42 move. In general, no insn containing hard regs should be changed
43 after this pass is done.
45 * The form of the output:
47 After this pass, hard register numbers represent the distance from
48 the current top of stack to the desired register. A reference to
49 FIRST_STACK_REG references the top of stack, FIRST_STACK_REG + 1,
50 represents the register just below that, and so forth. Also, REG_DEAD
51 notes indicate whether or not a stack register should be popped.
53 A "swap" insn looks like a parallel of two patterns, where each
54 pattern is a SET: one sets A to B, the other B to A.
56 A "push" or "load" insn is a SET whose SET_DEST is FIRST_STACK_REG
57 and whose SET_DEST is REG or MEM. Any other SET_DEST, such as PLUS,
58 will replace the existing stack top, not push a new value.
60 A store insn is a SET whose SET_DEST is FIRST_STACK_REG, and whose
61 SET_SRC is REG or MEM.
63 The case where the SET_SRC and SET_DEST are both FIRST_STACK_REG
64 appears ambiguous. As a special case, the presence of a REG_DEAD note
65 for FIRST_STACK_REG differentiates between a load insn and a pop.
67 If a REG_DEAD is present, the insn represents a "pop" that discards
68 the top of the register stack. If there is no REG_DEAD note, then the
69 insn represents a "dup" or a push of the current top of stack onto the
74 Existing REG_DEAD and REG_UNUSED notes for stack registers are
75 deleted and recreated from scratch. REG_DEAD is never created for a
76 SET_DEST, only REG_UNUSED.
80 There are several rules on the usage of stack-like regs in
81 asm_operands insns. These rules apply only to the operands that are
84 1. Given a set of input regs that die in an asm_operands, it is
85 necessary to know which are implicitly popped by the asm, and
86 which must be explicitly popped by gcc.
88 An input reg that is implicitly popped by the asm must be
89 explicitly clobbered, unless it is constrained to match an
92 2. For any input reg that is implicitly popped by an asm, it is
93 necessary to know how to adjust the stack to compensate for the pop.
94 If any non-popped input is closer to the top of the reg-stack than
95 the implicitly popped reg, it would not be possible to know what the
96 stack looked like - it's not clear how the rest of the stack "slides
99 All implicitly popped input regs must be closer to the top of
100 the reg-stack than any input that is not implicitly popped.
102 3. It is possible that if an input dies in an insn, reload might
103 use the input reg for an output reload. Consider this example:
105 asm ("foo" : "=t" (a) : "f" (b));
107 This asm says that input B is not popped by the asm, and that
108 the asm pushes a result onto the reg-stack, ie, the stack is one
109 deeper after the asm than it was before. But, it is possible that
110 reload will think that it can use the same reg for both the input and
111 the output, if input B dies in this insn.
113 If any input operand uses the "f" constraint, all output reg
114 constraints must use the "&" earlyclobber.
116 The asm above would be written as
118 asm ("foo" : "=&t" (a) : "f" (b));
120 4. Some operands need to be in particular places on the stack. All
121 output operands fall in this category - there is no other way to
122 know which regs the outputs appear in unless the user indicates
123 this in the constraints.
125 Output operands must specifically indicate which reg an output
126 appears in after an asm. "=f" is not allowed: the operand
127 constraints must select a class with a single reg.
129 5. Output operands may not be "inserted" between existing stack regs.
130 Since no 387 opcode uses a read/write operand, all output operands
131 are dead before the asm_operands, and are pushed by the asm_operands.
132 It makes no sense to push anywhere but the top of the reg-stack.
134 Output operands must start at the top of the reg-stack: output
135 operands may not "skip" a reg.
137 6. Some asm statements may need extra stack space for internal
138 calculations. This can be guaranteed by clobbering stack registers
139 unrelated to the inputs and outputs.
141 Here are a couple of reasonable asms to want to write. This asm
142 takes one input, which is internally popped, and produces two outputs.
144 asm ("fsincos" : "=t" (cos), "=u" (sin) : "0" (inp));
146 This asm takes two inputs, which are popped by the fyl2xp1 opcode,
147 and replaces them with one output. The user must code the "st(1)"
148 clobber for reg-stack.c to know that fyl2xp1 pops both inputs.
150 asm ("fyl2xp1" : "=t" (result) : "0" (x), "u" (y) : "st(1)");
156 #include "coretypes.h"
161 #include "function.h"
162 #include "insn-config.h"
164 #include "hard-reg-set.h"
169 #include "basic-block.h"
174 /* We use this array to cache info about insns, because otherwise we
175 spend too much time in stack_regs_mentioned_p.
177 Indexed by insn UIDs. A value of zero is uninitialized, one indicates
178 the insn uses stack registers, two indicates the insn does not use
180 static GTY(()) varray_type stack_regs_mentioned_data
;
184 #define REG_STACK_SIZE (LAST_STACK_REG - FIRST_STACK_REG + 1)
186 /* This is the basic stack record. TOP is an index into REG[] such
187 that REG[TOP] is the top of stack. If TOP is -1 the stack is empty.
189 If TOP is -2, REG[] is not yet initialized. Stack initialization
190 consists of placing each live reg in array `reg' and setting `top'
193 REG_SET indicates which registers are live. */
195 typedef struct stack_def
197 int top
; /* index to top stack element */
198 HARD_REG_SET reg_set
; /* set of live registers */
199 unsigned char reg
[REG_STACK_SIZE
];/* register - stack mapping */
202 /* This is used to carry information about basic blocks. It is
203 attached to the AUX field of the standard CFG block. */
205 typedef struct block_info_def
207 struct stack_def stack_in
; /* Input stack configuration. */
208 struct stack_def stack_out
; /* Output stack configuration. */
209 HARD_REG_SET out_reg_set
; /* Stack regs live on output. */
210 int done
; /* True if block already converted. */
211 int predecessors
; /* Number of predecessors that needs
215 #define BLOCK_INFO(B) ((block_info) (B)->aux)
217 /* Passed to change_stack to indicate where to emit insns. */
224 /* The block we're currently working on. */
225 static basic_block current_block
;
227 /* This is the register file for all register after conversion. */
229 FP_mode_reg
[LAST_STACK_REG
+1-FIRST_STACK_REG
][(int) MAX_MACHINE_MODE
];
231 #define FP_MODE_REG(regno,mode) \
232 (FP_mode_reg[(regno)-FIRST_STACK_REG][(int) (mode)])
234 /* Used to initialize uninitialized registers. */
237 /* Forward declarations */
239 static int stack_regs_mentioned_p (rtx pat
);
240 static void straighten_stack (rtx
, stack
);
241 static void pop_stack (stack
, int);
242 static rtx
*get_true_reg (rtx
*);
244 static int check_asm_stack_operands (rtx
);
245 static int get_asm_operand_n_inputs (rtx
);
246 static rtx
stack_result (tree
);
247 static void replace_reg (rtx
*, int);
248 static void remove_regno_note (rtx
, enum reg_note
, unsigned int);
249 static int get_hard_regnum (stack
, rtx
);
250 static rtx
emit_pop_insn (rtx
, stack
, rtx
, enum emit_where
);
251 static void emit_swap_insn (rtx
, stack
, rtx
);
252 static bool move_for_stack_reg (rtx
, stack
, rtx
);
253 static int swap_rtx_condition_1 (rtx
);
254 static int swap_rtx_condition (rtx
);
255 static void compare_for_stack_reg (rtx
, stack
, rtx
);
256 static bool subst_stack_regs_pat (rtx
, stack
, rtx
);
257 static void subst_asm_stack_regs (rtx
, stack
);
258 static bool subst_stack_regs (rtx
, stack
);
259 static void change_stack (rtx
, stack
, stack
, enum emit_where
);
260 static int convert_regs_entry (void);
261 static void convert_regs_exit (void);
262 static int convert_regs_1 (FILE *, basic_block
);
263 static int convert_regs_2 (FILE *, basic_block
);
264 static int convert_regs (FILE *);
265 static void print_stack (FILE *, stack
);
266 static rtx
next_flags_user (rtx
);
267 static void record_label_references (rtx
, rtx
);
268 static bool compensate_edge (edge
, FILE *);
270 /* Return nonzero if any stack register is mentioned somewhere within PAT. */
273 stack_regs_mentioned_p (rtx pat
)
278 if (STACK_REG_P (pat
))
281 fmt
= GET_RTX_FORMAT (GET_CODE (pat
));
282 for (i
= GET_RTX_LENGTH (GET_CODE (pat
)) - 1; i
>= 0; i
--)
288 for (j
= XVECLEN (pat
, i
) - 1; j
>= 0; j
--)
289 if (stack_regs_mentioned_p (XVECEXP (pat
, i
, j
)))
292 else if (fmt
[i
] == 'e' && stack_regs_mentioned_p (XEXP (pat
, i
)))
299 /* Return nonzero if INSN mentions stacked registers, else return zero. */
302 stack_regs_mentioned (rtx insn
)
304 unsigned int uid
, max
;
307 if (! INSN_P (insn
) || !stack_regs_mentioned_data
)
310 uid
= INSN_UID (insn
);
311 max
= VARRAY_SIZE (stack_regs_mentioned_data
);
314 /* Allocate some extra size to avoid too many reallocs, but
315 do not grow too quickly. */
316 max
= uid
+ uid
/ 20;
317 VARRAY_GROW (stack_regs_mentioned_data
, max
);
320 test
= VARRAY_CHAR (stack_regs_mentioned_data
, uid
);
323 /* This insn has yet to be examined. Do so now. */
324 test
= stack_regs_mentioned_p (PATTERN (insn
)) ? 1 : 2;
325 VARRAY_CHAR (stack_regs_mentioned_data
, uid
) = test
;
331 static rtx ix86_flags_rtx
;
334 next_flags_user (rtx insn
)
336 /* Search forward looking for the first use of this value.
337 Stop at block boundaries. */
339 while (insn
!= current_block
->end
)
341 insn
= NEXT_INSN (insn
);
343 if (INSN_P (insn
) && reg_mentioned_p (ix86_flags_rtx
, PATTERN (insn
)))
346 if (GET_CODE (insn
) == CALL_INSN
)
352 /* Reorganize the stack into ascending numbers,
356 straighten_stack (rtx insn
, stack regstack
)
358 struct stack_def temp_stack
;
361 /* If there is only a single register on the stack, then the stack is
362 already in increasing order and no reorganization is needed.
364 Similarly if the stack is empty. */
365 if (regstack
->top
<= 0)
368 COPY_HARD_REG_SET (temp_stack
.reg_set
, regstack
->reg_set
);
370 for (top
= temp_stack
.top
= regstack
->top
; top
>= 0; top
--)
371 temp_stack
.reg
[top
] = FIRST_STACK_REG
+ temp_stack
.top
- top
;
373 change_stack (insn
, regstack
, &temp_stack
, EMIT_AFTER
);
376 /* Pop a register from the stack. */
379 pop_stack (stack regstack
, int regno
)
381 int top
= regstack
->top
;
383 CLEAR_HARD_REG_BIT (regstack
->reg_set
, regno
);
385 /* If regno was not at the top of stack then adjust stack. */
386 if (regstack
->reg
[top
] != regno
)
389 for (i
= regstack
->top
; i
>= 0; i
--)
390 if (regstack
->reg
[i
] == regno
)
393 for (j
= i
; j
< top
; j
++)
394 regstack
->reg
[j
] = regstack
->reg
[j
+ 1];
400 /* Convert register usage from "flat" register file usage to a "stack
401 register file. FIRST is the first insn in the function, FILE is the
404 Construct a CFG and run life analysis. Then convert each insn one
405 by one. Run a last cleanup_cfg pass, if optimizing, to eliminate
406 code duplication created when the converter inserts pop insns on
410 reg_to_stack (rtx first
, FILE *file
)
416 /* Clean up previous run. */
417 stack_regs_mentioned_data
= 0;
419 /* See if there is something to do. Flow analysis is quite
420 expensive so we might save some compilation time. */
421 for (i
= FIRST_STACK_REG
; i
<= LAST_STACK_REG
; i
++)
422 if (regs_ever_live
[i
])
424 if (i
> LAST_STACK_REG
)
427 /* Ok, floating point instructions exist. If not optimizing,
428 build the CFG and run life analysis.
429 Also need to rebuild life when superblock scheduling is done
430 as it don't update liveness yet. */
432 || (flag_sched2_use_superblocks
433 && flag_schedule_insns_after_reload
))
435 count_or_remove_death_notes (NULL
, 1);
436 life_analysis (first
, file
, PROP_DEATH_NOTES
);
438 mark_dfs_back_edges ();
440 /* Set up block info for each basic block. */
441 alloc_aux_for_blocks (sizeof (struct block_info_def
));
442 FOR_EACH_BB_REVERSE (bb
)
445 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
446 if (!(e
->flags
& EDGE_DFS_BACK
)
447 && e
->src
!= ENTRY_BLOCK_PTR
)
448 BLOCK_INFO (bb
)->predecessors
++;
451 /* Create the replacement registers up front. */
452 for (i
= FIRST_STACK_REG
; i
<= LAST_STACK_REG
; i
++)
454 enum machine_mode mode
;
455 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_FLOAT
);
457 mode
= GET_MODE_WIDER_MODE (mode
))
458 FP_MODE_REG (i
, mode
) = gen_rtx_REG (mode
, i
);
459 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_COMPLEX_FLOAT
);
461 mode
= GET_MODE_WIDER_MODE (mode
))
462 FP_MODE_REG (i
, mode
) = gen_rtx_REG (mode
, i
);
465 ix86_flags_rtx
= gen_rtx_REG (CCmode
, FLAGS_REG
);
467 /* A QNaN for initializing uninitialized variables.
469 ??? We can't load from constant memory in PIC mode, because
470 we're inserting these instructions before the prologue and
471 the PIC register hasn't been set up. In that case, fall back
472 on zero, which we can get from `ldz'. */
475 nan
= CONST0_RTX (SFmode
);
478 nan
= gen_lowpart (SFmode
, GEN_INT (0x7fc00000));
479 nan
= force_const_mem (SFmode
, nan
);
482 /* Allocate a cache for stack_regs_mentioned. */
483 max_uid
= get_max_uid ();
484 VARRAY_CHAR_INIT (stack_regs_mentioned_data
, max_uid
+ 1,
485 "stack_regs_mentioned cache");
489 free_aux_for_blocks ();
493 /* Check PAT, which is in INSN, for LABEL_REFs. Add INSN to the
494 label's chain of references, and note which insn contains each
498 record_label_references (rtx insn
, rtx pat
)
500 enum rtx_code code
= GET_CODE (pat
);
504 if (code
== LABEL_REF
)
506 rtx label
= XEXP (pat
, 0);
509 if (GET_CODE (label
) != CODE_LABEL
)
512 /* If this is an undefined label, LABEL_REFS (label) contains
514 if (INSN_UID (label
) == 0)
517 /* Don't make a duplicate in the code_label's chain. */
519 for (ref
= LABEL_REFS (label
);
521 ref
= LABEL_NEXTREF (ref
))
522 if (CONTAINING_INSN (ref
) == insn
)
525 CONTAINING_INSN (pat
) = insn
;
526 LABEL_NEXTREF (pat
) = LABEL_REFS (label
);
527 LABEL_REFS (label
) = pat
;
532 fmt
= GET_RTX_FORMAT (code
);
533 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
536 record_label_references (insn
, XEXP (pat
, i
));
540 for (j
= 0; j
< XVECLEN (pat
, i
); j
++)
541 record_label_references (insn
, XVECEXP (pat
, i
, j
));
546 /* Return a pointer to the REG expression within PAT. If PAT is not a
547 REG, possible enclosed by a conversion rtx, return the inner part of
548 PAT that stopped the search. */
551 get_true_reg (rtx
*pat
)
554 switch (GET_CODE (*pat
))
557 /* Eliminate FP subregister accesses in favor of the
558 actual FP register in use. */
561 if (FP_REG_P (subreg
= SUBREG_REG (*pat
)))
563 int regno_off
= subreg_regno_offset (REGNO (subreg
),
567 *pat
= FP_MODE_REG (REGNO (subreg
) + regno_off
,
576 pat
= & XEXP (*pat
, 0);
580 /* Set if we find any malformed asms in a block. */
581 static bool any_malformed_asm
;
583 /* There are many rules that an asm statement for stack-like regs must
584 follow. Those rules are explained at the top of this file: the rule
585 numbers below refer to that explanation. */
588 check_asm_stack_operands (rtx insn
)
592 int malformed_asm
= 0;
593 rtx body
= PATTERN (insn
);
595 char reg_used_as_output
[FIRST_PSEUDO_REGISTER
];
596 char implicitly_dies
[FIRST_PSEUDO_REGISTER
];
599 rtx
*clobber_reg
= 0;
600 int n_inputs
, n_outputs
;
602 /* Find out what the constraints require. If no constraint
603 alternative matches, this asm is malformed. */
605 constrain_operands (1);
606 alt
= which_alternative
;
608 preprocess_constraints ();
610 n_inputs
= get_asm_operand_n_inputs (body
);
611 n_outputs
= recog_data
.n_operands
- n_inputs
;
616 /* Avoid further trouble with this insn. */
617 PATTERN (insn
) = gen_rtx_USE (VOIDmode
, const0_rtx
);
621 /* Strip SUBREGs here to make the following code simpler. */
622 for (i
= 0; i
< recog_data
.n_operands
; i
++)
623 if (GET_CODE (recog_data
.operand
[i
]) == SUBREG
624 && GET_CODE (SUBREG_REG (recog_data
.operand
[i
])) == REG
)
625 recog_data
.operand
[i
] = SUBREG_REG (recog_data
.operand
[i
]);
627 /* Set up CLOBBER_REG. */
631 if (GET_CODE (body
) == PARALLEL
)
633 clobber_reg
= alloca (XVECLEN (body
, 0) * sizeof (rtx
));
635 for (i
= 0; i
< XVECLEN (body
, 0); i
++)
636 if (GET_CODE (XVECEXP (body
, 0, i
)) == CLOBBER
)
638 rtx clobber
= XVECEXP (body
, 0, i
);
639 rtx reg
= XEXP (clobber
, 0);
641 if (GET_CODE (reg
) == SUBREG
&& GET_CODE (SUBREG_REG (reg
)) == REG
)
642 reg
= SUBREG_REG (reg
);
644 if (STACK_REG_P (reg
))
646 clobber_reg
[n_clobbers
] = reg
;
652 /* Enforce rule #4: Output operands must specifically indicate which
653 reg an output appears in after an asm. "=f" is not allowed: the
654 operand constraints must select a class with a single reg.
656 Also enforce rule #5: Output operands must start at the top of
657 the reg-stack: output operands may not "skip" a reg. */
659 memset (reg_used_as_output
, 0, sizeof (reg_used_as_output
));
660 for (i
= 0; i
< n_outputs
; i
++)
661 if (STACK_REG_P (recog_data
.operand
[i
]))
663 if (reg_class_size
[(int) recog_op_alt
[i
][alt
].class] != 1)
665 error_for_asm (insn
, "output constraint %d must specify a single register", i
);
672 for (j
= 0; j
< n_clobbers
; j
++)
673 if (REGNO (recog_data
.operand
[i
]) == REGNO (clobber_reg
[j
]))
675 error_for_asm (insn
, "output constraint %d cannot be specified together with \"%s\" clobber",
676 i
, reg_names
[REGNO (clobber_reg
[j
])]);
681 reg_used_as_output
[REGNO (recog_data
.operand
[i
])] = 1;
686 /* Search for first non-popped reg. */
687 for (i
= FIRST_STACK_REG
; i
< LAST_STACK_REG
+ 1; i
++)
688 if (! reg_used_as_output
[i
])
691 /* If there are any other popped regs, that's an error. */
692 for (; i
< LAST_STACK_REG
+ 1; i
++)
693 if (reg_used_as_output
[i
])
696 if (i
!= LAST_STACK_REG
+ 1)
698 error_for_asm (insn
, "output regs must be grouped at top of stack");
702 /* Enforce rule #2: All implicitly popped input regs must be closer
703 to the top of the reg-stack than any input that is not implicitly
706 memset (implicitly_dies
, 0, sizeof (implicitly_dies
));
707 for (i
= n_outputs
; i
< n_outputs
+ n_inputs
; i
++)
708 if (STACK_REG_P (recog_data
.operand
[i
]))
710 /* An input reg is implicitly popped if it is tied to an
711 output, or if there is a CLOBBER for it. */
714 for (j
= 0; j
< n_clobbers
; j
++)
715 if (operands_match_p (clobber_reg
[j
], recog_data
.operand
[i
]))
718 if (j
< n_clobbers
|| recog_op_alt
[i
][alt
].matches
>= 0)
719 implicitly_dies
[REGNO (recog_data
.operand
[i
])] = 1;
722 /* Search for first non-popped reg. */
723 for (i
= FIRST_STACK_REG
; i
< LAST_STACK_REG
+ 1; i
++)
724 if (! implicitly_dies
[i
])
727 /* If there are any other popped regs, that's an error. */
728 for (; i
< LAST_STACK_REG
+ 1; i
++)
729 if (implicitly_dies
[i
])
732 if (i
!= LAST_STACK_REG
+ 1)
735 "implicitly popped regs must be grouped at top of stack");
739 /* Enforce rule #3: If any input operand uses the "f" constraint, all
740 output constraints must use the "&" earlyclobber.
742 ??? Detect this more deterministically by having constrain_asm_operands
743 record any earlyclobber. */
745 for (i
= n_outputs
; i
< n_outputs
+ n_inputs
; i
++)
746 if (recog_op_alt
[i
][alt
].matches
== -1)
750 for (j
= 0; j
< n_outputs
; j
++)
751 if (operands_match_p (recog_data
.operand
[j
], recog_data
.operand
[i
]))
754 "output operand %d must use `&' constraint", j
);
761 /* Avoid further trouble with this insn. */
762 PATTERN (insn
) = gen_rtx_USE (VOIDmode
, const0_rtx
);
763 any_malformed_asm
= true;
770 /* Calculate the number of inputs and outputs in BODY, an
771 asm_operands. N_OPERANDS is the total number of operands, and
772 N_INPUTS and N_OUTPUTS are pointers to ints into which the results are
776 get_asm_operand_n_inputs (rtx body
)
778 if (GET_CODE (body
) == SET
&& GET_CODE (SET_SRC (body
)) == ASM_OPERANDS
)
779 return ASM_OPERANDS_INPUT_LENGTH (SET_SRC (body
));
781 else if (GET_CODE (body
) == ASM_OPERANDS
)
782 return ASM_OPERANDS_INPUT_LENGTH (body
);
784 else if (GET_CODE (body
) == PARALLEL
785 && GET_CODE (XVECEXP (body
, 0, 0)) == SET
)
786 return ASM_OPERANDS_INPUT_LENGTH (SET_SRC (XVECEXP (body
, 0, 0)));
788 else if (GET_CODE (body
) == PARALLEL
789 && GET_CODE (XVECEXP (body
, 0, 0)) == ASM_OPERANDS
)
790 return ASM_OPERANDS_INPUT_LENGTH (XVECEXP (body
, 0, 0));
795 /* If current function returns its result in an fp stack register,
796 return the REG. Otherwise, return 0. */
799 stack_result (tree decl
)
803 /* If the value is supposed to be returned in memory, then clearly
804 it is not returned in a stack register. */
805 if (aggregate_value_p (DECL_RESULT (decl
), decl
))
808 result
= DECL_RTL_IF_SET (DECL_RESULT (decl
));
811 #ifdef FUNCTION_OUTGOING_VALUE
813 = FUNCTION_OUTGOING_VALUE (TREE_TYPE (DECL_RESULT (decl
)), decl
);
815 result
= FUNCTION_VALUE (TREE_TYPE (DECL_RESULT (decl
)), decl
);
819 return result
!= 0 && STACK_REG_P (result
) ? result
: 0;
824 * This section deals with stack register substitution, and forms the second
828 /* Replace REG, which is a pointer to a stack reg RTX, with an RTX for
829 the desired hard REGNO. */
832 replace_reg (rtx
*reg
, int regno
)
834 if (regno
< FIRST_STACK_REG
|| regno
> LAST_STACK_REG
835 || ! STACK_REG_P (*reg
))
838 switch (GET_MODE_CLASS (GET_MODE (*reg
)))
842 case MODE_COMPLEX_FLOAT
:;
845 *reg
= FP_MODE_REG (regno
, GET_MODE (*reg
));
848 /* Remove a note of type NOTE, which must be found, for register
849 number REGNO from INSN. Remove only one such note. */
852 remove_regno_note (rtx insn
, enum reg_note note
, unsigned int regno
)
854 rtx
*note_link
, this;
856 note_link
= ®_NOTES (insn
);
857 for (this = *note_link
; this; this = XEXP (this, 1))
858 if (REG_NOTE_KIND (this) == note
859 && REG_P (XEXP (this, 0)) && REGNO (XEXP (this, 0)) == regno
)
861 *note_link
= XEXP (this, 1);
865 note_link
= &XEXP (this, 1);
870 /* Find the hard register number of virtual register REG in REGSTACK.
871 The hard register number is relative to the top of the stack. -1 is
872 returned if the register is not found. */
875 get_hard_regnum (stack regstack
, rtx reg
)
879 if (! STACK_REG_P (reg
))
882 for (i
= regstack
->top
; i
>= 0; i
--)
883 if (regstack
->reg
[i
] == REGNO (reg
))
886 return i
>= 0 ? (FIRST_STACK_REG
+ regstack
->top
- i
) : -1;
889 /* Emit an insn to pop virtual register REG before or after INSN.
890 REGSTACK is the stack state after INSN and is updated to reflect this
891 pop. WHEN is either emit_insn_before or emit_insn_after. A pop insn
892 is represented as a SET whose destination is the register to be popped
893 and source is the top of stack. A death note for the top of stack
894 cases the movdf pattern to pop. */
897 emit_pop_insn (rtx insn
, stack regstack
, rtx reg
, enum emit_where where
)
899 rtx pop_insn
, pop_rtx
;
902 /* For complex types take care to pop both halves. These may survive in
903 CLOBBER and USE expressions. */
904 if (COMPLEX_MODE_P (GET_MODE (reg
)))
906 rtx reg1
= FP_MODE_REG (REGNO (reg
), DFmode
);
907 rtx reg2
= FP_MODE_REG (REGNO (reg
) + 1, DFmode
);
910 if (get_hard_regnum (regstack
, reg1
) >= 0)
911 pop_insn
= emit_pop_insn (insn
, regstack
, reg1
, where
);
912 if (get_hard_regnum (regstack
, reg2
) >= 0)
913 pop_insn
= emit_pop_insn (insn
, regstack
, reg2
, where
);
919 hard_regno
= get_hard_regnum (regstack
, reg
);
921 if (hard_regno
< FIRST_STACK_REG
)
924 pop_rtx
= gen_rtx_SET (VOIDmode
, FP_MODE_REG (hard_regno
, DFmode
),
925 FP_MODE_REG (FIRST_STACK_REG
, DFmode
));
927 if (where
== EMIT_AFTER
)
928 pop_insn
= emit_insn_after (pop_rtx
, insn
);
930 pop_insn
= emit_insn_before (pop_rtx
, insn
);
933 = gen_rtx_EXPR_LIST (REG_DEAD
, FP_MODE_REG (FIRST_STACK_REG
, DFmode
),
934 REG_NOTES (pop_insn
));
936 regstack
->reg
[regstack
->top
- (hard_regno
- FIRST_STACK_REG
)]
937 = regstack
->reg
[regstack
->top
];
939 CLEAR_HARD_REG_BIT (regstack
->reg_set
, REGNO (reg
));
944 /* Emit an insn before or after INSN to swap virtual register REG with
945 the top of stack. REGSTACK is the stack state before the swap, and
946 is updated to reflect the swap. A swap insn is represented as a
947 PARALLEL of two patterns: each pattern moves one reg to the other.
949 If REG is already at the top of the stack, no insn is emitted. */
952 emit_swap_insn (rtx insn
, stack regstack
, rtx reg
)
956 int tmp
, other_reg
; /* swap regno temps */
957 rtx i1
; /* the stack-reg insn prior to INSN */
958 rtx i1set
= NULL_RTX
; /* the SET rtx within I1 */
960 hard_regno
= get_hard_regnum (regstack
, reg
);
962 if (hard_regno
< FIRST_STACK_REG
)
964 if (hard_regno
== FIRST_STACK_REG
)
967 other_reg
= regstack
->top
- (hard_regno
- FIRST_STACK_REG
);
969 tmp
= regstack
->reg
[other_reg
];
970 regstack
->reg
[other_reg
] = regstack
->reg
[regstack
->top
];
971 regstack
->reg
[regstack
->top
] = tmp
;
973 /* Find the previous insn involving stack regs, but don't pass a
976 if (current_block
&& insn
!= current_block
->head
)
978 rtx tmp
= PREV_INSN (insn
);
979 rtx limit
= PREV_INSN (current_block
->head
);
982 if (GET_CODE (tmp
) == CODE_LABEL
983 || GET_CODE (tmp
) == CALL_INSN
984 || NOTE_INSN_BASIC_BLOCK_P (tmp
)
985 || (GET_CODE (tmp
) == INSN
986 && stack_regs_mentioned (tmp
)))
991 tmp
= PREV_INSN (tmp
);
996 && (i1set
= single_set (i1
)) != NULL_RTX
)
998 rtx i1src
= *get_true_reg (&SET_SRC (i1set
));
999 rtx i1dest
= *get_true_reg (&SET_DEST (i1set
));
1001 /* If the previous register stack push was from the reg we are to
1002 swap with, omit the swap. */
1004 if (GET_CODE (i1dest
) == REG
&& REGNO (i1dest
) == FIRST_STACK_REG
1005 && GET_CODE (i1src
) == REG
1006 && REGNO (i1src
) == (unsigned) hard_regno
- 1
1007 && find_regno_note (i1
, REG_DEAD
, FIRST_STACK_REG
) == NULL_RTX
)
1010 /* If the previous insn wrote to the reg we are to swap with,
1013 if (GET_CODE (i1dest
) == REG
&& REGNO (i1dest
) == (unsigned) hard_regno
1014 && GET_CODE (i1src
) == REG
&& REGNO (i1src
) == FIRST_STACK_REG
1015 && find_regno_note (i1
, REG_DEAD
, FIRST_STACK_REG
) == NULL_RTX
)
1019 swap_rtx
= gen_swapxf (FP_MODE_REG (hard_regno
, XFmode
),
1020 FP_MODE_REG (FIRST_STACK_REG
, XFmode
));
1023 emit_insn_after (swap_rtx
, i1
);
1024 else if (current_block
)
1025 emit_insn_before (swap_rtx
, current_block
->head
);
1027 emit_insn_before (swap_rtx
, insn
);
1030 /* Handle a move to or from a stack register in PAT, which is in INSN.
1031 REGSTACK is the current stack. Return whether a control flow insn
1032 was deleted in the process. */
1035 move_for_stack_reg (rtx insn
, stack regstack
, rtx pat
)
1037 rtx
*psrc
= get_true_reg (&SET_SRC (pat
));
1038 rtx
*pdest
= get_true_reg (&SET_DEST (pat
));
1041 bool control_flow_insn_deleted
= false;
1043 src
= *psrc
; dest
= *pdest
;
1045 if (STACK_REG_P (src
) && STACK_REG_P (dest
))
1047 /* Write from one stack reg to another. If SRC dies here, then
1048 just change the register mapping and delete the insn. */
1050 note
= find_regno_note (insn
, REG_DEAD
, REGNO (src
));
1055 /* If this is a no-op move, there must not be a REG_DEAD note. */
1056 if (REGNO (src
) == REGNO (dest
))
1059 for (i
= regstack
->top
; i
>= 0; i
--)
1060 if (regstack
->reg
[i
] == REGNO (src
))
1063 /* The source must be live, and the dest must be dead. */
1064 if (i
< 0 || get_hard_regnum (regstack
, dest
) >= FIRST_STACK_REG
)
1067 /* It is possible that the dest is unused after this insn.
1068 If so, just pop the src. */
1070 if (find_regno_note (insn
, REG_UNUSED
, REGNO (dest
)))
1071 emit_pop_insn (insn
, regstack
, src
, EMIT_AFTER
);
1074 regstack
->reg
[i
] = REGNO (dest
);
1075 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (dest
));
1076 CLEAR_HARD_REG_BIT (regstack
->reg_set
, REGNO (src
));
1079 control_flow_insn_deleted
|= control_flow_insn_p (insn
);
1081 return control_flow_insn_deleted
;
1084 /* The source reg does not die. */
1086 /* If this appears to be a no-op move, delete it, or else it
1087 will confuse the machine description output patterns. But if
1088 it is REG_UNUSED, we must pop the reg now, as per-insn processing
1089 for REG_UNUSED will not work for deleted insns. */
1091 if (REGNO (src
) == REGNO (dest
))
1093 if (find_regno_note (insn
, REG_UNUSED
, REGNO (dest
)))
1094 emit_pop_insn (insn
, regstack
, dest
, EMIT_AFTER
);
1096 control_flow_insn_deleted
|= control_flow_insn_p (insn
);
1098 return control_flow_insn_deleted
;
1101 /* The destination ought to be dead. */
1102 if (get_hard_regnum (regstack
, dest
) >= FIRST_STACK_REG
)
1105 replace_reg (psrc
, get_hard_regnum (regstack
, src
));
1107 regstack
->reg
[++regstack
->top
] = REGNO (dest
);
1108 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (dest
));
1109 replace_reg (pdest
, FIRST_STACK_REG
);
1111 else if (STACK_REG_P (src
))
1113 /* Save from a stack reg to MEM, or possibly integer reg. Since
1114 only top of stack may be saved, emit an exchange first if
1117 emit_swap_insn (insn
, regstack
, src
);
1119 note
= find_regno_note (insn
, REG_DEAD
, REGNO (src
));
1122 replace_reg (&XEXP (note
, 0), FIRST_STACK_REG
);
1124 CLEAR_HARD_REG_BIT (regstack
->reg_set
, REGNO (src
));
1126 else if ((GET_MODE (src
) == XFmode
)
1127 && regstack
->top
< REG_STACK_SIZE
- 1)
1129 /* A 387 cannot write an XFmode value to a MEM without
1130 clobbering the source reg. The output code can handle
1131 this by reading back the value from the MEM.
1132 But it is more efficient to use a temp register if one is
1133 available. Push the source value here if the register
1134 stack is not full, and then write the value to memory via
1136 rtx push_rtx
, push_insn
;
1137 rtx top_stack_reg
= FP_MODE_REG (FIRST_STACK_REG
, GET_MODE (src
));
1139 push_rtx
= gen_movxf (top_stack_reg
, top_stack_reg
);
1140 push_insn
= emit_insn_before (push_rtx
, insn
);
1141 REG_NOTES (insn
) = gen_rtx_EXPR_LIST (REG_DEAD
, top_stack_reg
,
1145 replace_reg (psrc
, FIRST_STACK_REG
);
1147 else if (STACK_REG_P (dest
))
1149 /* Load from MEM, or possibly integer REG or constant, into the
1150 stack regs. The actual target is always the top of the
1151 stack. The stack mapping is changed to reflect that DEST is
1152 now at top of stack. */
1154 /* The destination ought to be dead. */
1155 if (get_hard_regnum (regstack
, dest
) >= FIRST_STACK_REG
)
1158 if (regstack
->top
>= REG_STACK_SIZE
)
1161 regstack
->reg
[++regstack
->top
] = REGNO (dest
);
1162 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (dest
));
1163 replace_reg (pdest
, FIRST_STACK_REG
);
1168 return control_flow_insn_deleted
;
1171 /* Swap the condition on a branch, if there is one. Return true if we
1172 found a condition to swap. False if the condition was not used as
1176 swap_rtx_condition_1 (rtx pat
)
1181 if (GET_RTX_CLASS (GET_CODE (pat
)) == '<')
1183 PUT_CODE (pat
, swap_condition (GET_CODE (pat
)));
1188 fmt
= GET_RTX_FORMAT (GET_CODE (pat
));
1189 for (i
= GET_RTX_LENGTH (GET_CODE (pat
)) - 1; i
>= 0; i
--)
1195 for (j
= XVECLEN (pat
, i
) - 1; j
>= 0; j
--)
1196 r
|= swap_rtx_condition_1 (XVECEXP (pat
, i
, j
));
1198 else if (fmt
[i
] == 'e')
1199 r
|= swap_rtx_condition_1 (XEXP (pat
, i
));
1207 swap_rtx_condition (rtx insn
)
1209 rtx pat
= PATTERN (insn
);
1211 /* We're looking for a single set to cc0 or an HImode temporary. */
1213 if (GET_CODE (pat
) == SET
1214 && GET_CODE (SET_DEST (pat
)) == REG
1215 && REGNO (SET_DEST (pat
)) == FLAGS_REG
)
1217 insn
= next_flags_user (insn
);
1218 if (insn
== NULL_RTX
)
1220 pat
= PATTERN (insn
);
1223 /* See if this is, or ends in, a fnstsw, aka unspec 9. If so, we're
1224 not doing anything with the cc value right now. We may be able to
1225 search for one though. */
1227 if (GET_CODE (pat
) == SET
1228 && GET_CODE (SET_SRC (pat
)) == UNSPEC
1229 && XINT (SET_SRC (pat
), 1) == UNSPEC_FNSTSW
)
1231 rtx dest
= SET_DEST (pat
);
1233 /* Search forward looking for the first use of this value.
1234 Stop at block boundaries. */
1235 while (insn
!= current_block
->end
)
1237 insn
= NEXT_INSN (insn
);
1238 if (INSN_P (insn
) && reg_mentioned_p (dest
, insn
))
1240 if (GET_CODE (insn
) == CALL_INSN
)
1244 /* So we've found the insn using this value. If it is anything
1245 other than sahf, aka unspec 10, or the value does not die
1246 (meaning we'd have to search further), then we must give up. */
1247 pat
= PATTERN (insn
);
1248 if (GET_CODE (pat
) != SET
1249 || GET_CODE (SET_SRC (pat
)) != UNSPEC
1250 || XINT (SET_SRC (pat
), 1) != UNSPEC_SAHF
1251 || ! dead_or_set_p (insn
, dest
))
1254 /* Now we are prepared to handle this as a normal cc0 setter. */
1255 insn
= next_flags_user (insn
);
1256 if (insn
== NULL_RTX
)
1258 pat
= PATTERN (insn
);
1261 if (swap_rtx_condition_1 (pat
))
1264 INSN_CODE (insn
) = -1;
1265 if (recog_memoized (insn
) == -1)
1267 /* In case the flags don't die here, recurse to try fix
1268 following user too. */
1269 else if (! dead_or_set_p (insn
, ix86_flags_rtx
))
1271 insn
= next_flags_user (insn
);
1272 if (!insn
|| !swap_rtx_condition (insn
))
1277 swap_rtx_condition_1 (pat
);
1285 /* Handle a comparison. Special care needs to be taken to avoid
1286 causing comparisons that a 387 cannot do correctly, such as EQ.
1288 Also, a pop insn may need to be emitted. The 387 does have an
1289 `fcompp' insn that can pop two regs, but it is sometimes too expensive
1290 to do this - a `fcomp' followed by a `fstpl %st(0)' may be easier to
1294 compare_for_stack_reg (rtx insn
, stack regstack
, rtx pat_src
)
1297 rtx src1_note
, src2_note
;
1300 src1
= get_true_reg (&XEXP (pat_src
, 0));
1301 src2
= get_true_reg (&XEXP (pat_src
, 1));
1302 flags_user
= next_flags_user (insn
);
1304 /* ??? If fxch turns out to be cheaper than fstp, give priority to
1305 registers that die in this insn - move those to stack top first. */
1306 if ((! STACK_REG_P (*src1
)
1307 || (STACK_REG_P (*src2
)
1308 && get_hard_regnum (regstack
, *src2
) == FIRST_STACK_REG
))
1309 && swap_rtx_condition (insn
))
1312 temp
= XEXP (pat_src
, 0);
1313 XEXP (pat_src
, 0) = XEXP (pat_src
, 1);
1314 XEXP (pat_src
, 1) = temp
;
1316 src1
= get_true_reg (&XEXP (pat_src
, 0));
1317 src2
= get_true_reg (&XEXP (pat_src
, 1));
1319 INSN_CODE (insn
) = -1;
1322 /* We will fix any death note later. */
1324 src1_note
= find_regno_note (insn
, REG_DEAD
, REGNO (*src1
));
1326 if (STACK_REG_P (*src2
))
1327 src2_note
= find_regno_note (insn
, REG_DEAD
, REGNO (*src2
));
1329 src2_note
= NULL_RTX
;
1331 emit_swap_insn (insn
, regstack
, *src1
);
1333 replace_reg (src1
, FIRST_STACK_REG
);
1335 if (STACK_REG_P (*src2
))
1336 replace_reg (src2
, get_hard_regnum (regstack
, *src2
));
1340 pop_stack (regstack
, REGNO (XEXP (src1_note
, 0)));
1341 replace_reg (&XEXP (src1_note
, 0), FIRST_STACK_REG
);
1344 /* If the second operand dies, handle that. But if the operands are
1345 the same stack register, don't bother, because only one death is
1346 needed, and it was just handled. */
1349 && ! (STACK_REG_P (*src1
) && STACK_REG_P (*src2
)
1350 && REGNO (*src1
) == REGNO (*src2
)))
1352 /* As a special case, two regs may die in this insn if src2 is
1353 next to top of stack and the top of stack also dies. Since
1354 we have already popped src1, "next to top of stack" is really
1355 at top (FIRST_STACK_REG) now. */
1357 if (get_hard_regnum (regstack
, XEXP (src2_note
, 0)) == FIRST_STACK_REG
1360 pop_stack (regstack
, REGNO (XEXP (src2_note
, 0)));
1361 replace_reg (&XEXP (src2_note
, 0), FIRST_STACK_REG
+ 1);
1365 /* The 386 can only represent death of the first operand in
1366 the case handled above. In all other cases, emit a separate
1367 pop and remove the death note from here. */
1369 /* link_cc0_insns (insn); */
1371 remove_regno_note (insn
, REG_DEAD
, REGNO (XEXP (src2_note
, 0)));
1373 emit_pop_insn (insn
, regstack
, XEXP (src2_note
, 0),
1379 /* Substitute new registers in PAT, which is part of INSN. REGSTACK
1380 is the current register layout. Return whether a control flow insn
1381 was deleted in the process. */
1384 subst_stack_regs_pat (rtx insn
, stack regstack
, rtx pat
)
1387 bool control_flow_insn_deleted
= false;
1389 switch (GET_CODE (pat
))
1392 /* Deaths in USE insns can happen in non optimizing compilation.
1393 Handle them by popping the dying register. */
1394 src
= get_true_reg (&XEXP (pat
, 0));
1395 if (STACK_REG_P (*src
)
1396 && find_regno_note (insn
, REG_DEAD
, REGNO (*src
)))
1398 emit_pop_insn (insn
, regstack
, *src
, EMIT_AFTER
);
1399 return control_flow_insn_deleted
;
1401 /* ??? Uninitialized USE should not happen. */
1402 else if (get_hard_regnum (regstack
, *src
) == -1)
1410 dest
= get_true_reg (&XEXP (pat
, 0));
1411 if (STACK_REG_P (*dest
))
1413 note
= find_reg_note (insn
, REG_DEAD
, *dest
);
1415 if (pat
!= PATTERN (insn
))
1417 /* The fix_truncdi_1 pattern wants to be able to allocate
1418 it's own scratch register. It does this by clobbering
1419 an fp reg so that it is assured of an empty reg-stack
1420 register. If the register is live, kill it now.
1421 Remove the DEAD/UNUSED note so we don't try to kill it
1425 emit_pop_insn (insn
, regstack
, *dest
, EMIT_BEFORE
);
1428 note
= find_reg_note (insn
, REG_UNUSED
, *dest
);
1432 remove_note (insn
, note
);
1433 replace_reg (dest
, FIRST_STACK_REG
+ 1);
1437 /* A top-level clobber with no REG_DEAD, and no hard-regnum
1438 indicates an uninitialized value. Because reload removed
1439 all other clobbers, this must be due to a function
1440 returning without a value. Load up a NaN. */
1443 && get_hard_regnum (regstack
, *dest
) == -1)
1445 pat
= gen_rtx_SET (VOIDmode
,
1446 FP_MODE_REG (REGNO (*dest
), SFmode
),
1448 PATTERN (insn
) = pat
;
1449 control_flow_insn_deleted
|= move_for_stack_reg (insn
, regstack
, pat
);
1451 if (! note
&& COMPLEX_MODE_P (GET_MODE (*dest
))
1452 && get_hard_regnum (regstack
, FP_MODE_REG (REGNO (*dest
), DFmode
)) == -1)
1454 pat
= gen_rtx_SET (VOIDmode
,
1455 FP_MODE_REG (REGNO (*dest
) + 1, SFmode
),
1457 PATTERN (insn
) = pat
;
1458 control_flow_insn_deleted
|= move_for_stack_reg (insn
, regstack
, pat
);
1467 rtx
*src1
= (rtx
*) 0, *src2
;
1468 rtx src1_note
, src2_note
;
1471 dest
= get_true_reg (&SET_DEST (pat
));
1472 src
= get_true_reg (&SET_SRC (pat
));
1473 pat_src
= SET_SRC (pat
);
1475 /* See if this is a `movM' pattern, and handle elsewhere if so. */
1476 if (STACK_REG_P (*src
)
1477 || (STACK_REG_P (*dest
)
1478 && (GET_CODE (*src
) == REG
|| GET_CODE (*src
) == MEM
1479 || GET_CODE (*src
) == CONST_DOUBLE
)))
1481 control_flow_insn_deleted
|= move_for_stack_reg (insn
, regstack
, pat
);
1485 switch (GET_CODE (pat_src
))
1488 compare_for_stack_reg (insn
, regstack
, pat_src
);
1494 for (count
= HARD_REGNO_NREGS (REGNO (*dest
), GET_MODE (*dest
));
1497 regstack
->reg
[++regstack
->top
] = REGNO (*dest
) + count
;
1498 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (*dest
) + count
);
1501 replace_reg (dest
, FIRST_STACK_REG
);
1505 /* This is a `tstM2' case. */
1506 if (*dest
!= cc0_rtx
)
1512 case FLOAT_TRUNCATE
:
1516 /* These insns only operate on the top of the stack. DEST might
1517 be cc0_rtx if we're processing a tstM pattern. Also, it's
1518 possible that the tstM case results in a REG_DEAD note on the
1522 src1
= get_true_reg (&XEXP (pat_src
, 0));
1524 emit_swap_insn (insn
, regstack
, *src1
);
1526 src1_note
= find_regno_note (insn
, REG_DEAD
, REGNO (*src1
));
1528 if (STACK_REG_P (*dest
))
1529 replace_reg (dest
, FIRST_STACK_REG
);
1533 replace_reg (&XEXP (src1_note
, 0), FIRST_STACK_REG
);
1535 CLEAR_HARD_REG_BIT (regstack
->reg_set
, REGNO (*src1
));
1538 replace_reg (src1
, FIRST_STACK_REG
);
1543 /* On i386, reversed forms of subM3 and divM3 exist for
1544 MODE_FLOAT, so the same code that works for addM3 and mulM3
1548 /* These insns can accept the top of stack as a destination
1549 from a stack reg or mem, or can use the top of stack as a
1550 source and some other stack register (possibly top of stack)
1551 as a destination. */
1553 src1
= get_true_reg (&XEXP (pat_src
, 0));
1554 src2
= get_true_reg (&XEXP (pat_src
, 1));
1556 /* We will fix any death note later. */
1558 if (STACK_REG_P (*src1
))
1559 src1_note
= find_regno_note (insn
, REG_DEAD
, REGNO (*src1
));
1561 src1_note
= NULL_RTX
;
1562 if (STACK_REG_P (*src2
))
1563 src2_note
= find_regno_note (insn
, REG_DEAD
, REGNO (*src2
));
1565 src2_note
= NULL_RTX
;
1567 /* If either operand is not a stack register, then the dest
1568 must be top of stack. */
1570 if (! STACK_REG_P (*src1
) || ! STACK_REG_P (*src2
))
1571 emit_swap_insn (insn
, regstack
, *dest
);
1574 /* Both operands are REG. If neither operand is already
1575 at the top of stack, choose to make the one that is the dest
1576 the new top of stack. */
1578 int src1_hard_regnum
, src2_hard_regnum
;
1580 src1_hard_regnum
= get_hard_regnum (regstack
, *src1
);
1581 src2_hard_regnum
= get_hard_regnum (regstack
, *src2
);
1582 if (src1_hard_regnum
== -1 || src2_hard_regnum
== -1)
1585 if (src1_hard_regnum
!= FIRST_STACK_REG
1586 && src2_hard_regnum
!= FIRST_STACK_REG
)
1587 emit_swap_insn (insn
, regstack
, *dest
);
1590 if (STACK_REG_P (*src1
))
1591 replace_reg (src1
, get_hard_regnum (regstack
, *src1
));
1592 if (STACK_REG_P (*src2
))
1593 replace_reg (src2
, get_hard_regnum (regstack
, *src2
));
1597 rtx src1_reg
= XEXP (src1_note
, 0);
1599 /* If the register that dies is at the top of stack, then
1600 the destination is somewhere else - merely substitute it.
1601 But if the reg that dies is not at top of stack, then
1602 move the top of stack to the dead reg, as though we had
1603 done the insn and then a store-with-pop. */
1605 if (REGNO (src1_reg
) == regstack
->reg
[regstack
->top
])
1607 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (*dest
));
1608 replace_reg (dest
, get_hard_regnum (regstack
, *dest
));
1612 int regno
= get_hard_regnum (regstack
, src1_reg
);
1614 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (*dest
));
1615 replace_reg (dest
, regno
);
1617 regstack
->reg
[regstack
->top
- (regno
- FIRST_STACK_REG
)]
1618 = regstack
->reg
[regstack
->top
];
1621 CLEAR_HARD_REG_BIT (regstack
->reg_set
,
1622 REGNO (XEXP (src1_note
, 0)));
1623 replace_reg (&XEXP (src1_note
, 0), FIRST_STACK_REG
);
1628 rtx src2_reg
= XEXP (src2_note
, 0);
1629 if (REGNO (src2_reg
) == regstack
->reg
[regstack
->top
])
1631 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (*dest
));
1632 replace_reg (dest
, get_hard_regnum (regstack
, *dest
));
1636 int regno
= get_hard_regnum (regstack
, src2_reg
);
1638 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (*dest
));
1639 replace_reg (dest
, regno
);
1641 regstack
->reg
[regstack
->top
- (regno
- FIRST_STACK_REG
)]
1642 = regstack
->reg
[regstack
->top
];
1645 CLEAR_HARD_REG_BIT (regstack
->reg_set
,
1646 REGNO (XEXP (src2_note
, 0)));
1647 replace_reg (&XEXP (src2_note
, 0), FIRST_STACK_REG
);
1652 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (*dest
));
1653 replace_reg (dest
, get_hard_regnum (regstack
, *dest
));
1656 /* Keep operand 1 matching with destination. */
1657 if (GET_RTX_CLASS (GET_CODE (pat_src
)) == 'c'
1658 && REG_P (*src1
) && REG_P (*src2
)
1659 && REGNO (*src1
) != REGNO (*dest
))
1661 int tmp
= REGNO (*src1
);
1662 replace_reg (src1
, REGNO (*src2
));
1663 replace_reg (src2
, tmp
);
1668 switch (XINT (pat_src
, 1))
1672 case UNSPEC_FRNDINT
:
1674 /* These insns only operate on the top of the stack. */
1676 src1
= get_true_reg (&XVECEXP (pat_src
, 0, 0));
1678 emit_swap_insn (insn
, regstack
, *src1
);
1680 src1_note
= find_regno_note (insn
, REG_DEAD
, REGNO (*src1
));
1682 if (STACK_REG_P (*dest
))
1683 replace_reg (dest
, FIRST_STACK_REG
);
1687 replace_reg (&XEXP (src1_note
, 0), FIRST_STACK_REG
);
1689 CLEAR_HARD_REG_BIT (regstack
->reg_set
, REGNO (*src1
));
1692 replace_reg (src1
, FIRST_STACK_REG
);
1698 /* These insns operate on the top two stack slots. */
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
));
1707 struct stack_def temp_stack
;
1708 int regno
, j
, k
, temp
;
1710 temp_stack
= *regstack
;
1712 /* Place operand 1 at the top of stack. */
1713 regno
= get_hard_regnum (&temp_stack
, *src1
);
1716 if (regno
!= FIRST_STACK_REG
)
1718 k
= temp_stack
.top
- (regno
- FIRST_STACK_REG
);
1721 temp
= temp_stack
.reg
[k
];
1722 temp_stack
.reg
[k
] = temp_stack
.reg
[j
];
1723 temp_stack
.reg
[j
] = temp
;
1726 /* Place operand 2 next on the stack. */
1727 regno
= get_hard_regnum (&temp_stack
, *src2
);
1730 if (regno
!= FIRST_STACK_REG
+ 1)
1732 k
= temp_stack
.top
- (regno
- FIRST_STACK_REG
);
1733 j
= temp_stack
.top
- 1;
1735 temp
= temp_stack
.reg
[k
];
1736 temp_stack
.reg
[k
] = temp_stack
.reg
[j
];
1737 temp_stack
.reg
[j
] = temp
;
1740 change_stack (insn
, regstack
, &temp_stack
, EMIT_BEFORE
);
1743 replace_reg (src1
, FIRST_STACK_REG
);
1744 replace_reg (src2
, FIRST_STACK_REG
+ 1);
1747 replace_reg (&XEXP (src1_note
, 0), FIRST_STACK_REG
);
1749 replace_reg (&XEXP (src2_note
, 0), FIRST_STACK_REG
+ 1);
1751 /* Pop both input operands from the stack. */
1752 CLEAR_HARD_REG_BIT (regstack
->reg_set
,
1753 regstack
->reg
[regstack
->top
]);
1754 CLEAR_HARD_REG_BIT (regstack
->reg_set
,
1755 regstack
->reg
[regstack
->top
- 1]);
1758 /* Push the result back onto the stack. */
1759 regstack
->reg
[++regstack
->top
] = REGNO (*dest
);
1760 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (*dest
));
1761 replace_reg (dest
, FIRST_STACK_REG
);
1765 /* (unspec [(unspec [(compare)] UNSPEC_FNSTSW)] UNSPEC_SAHF)
1766 The combination matches the PPRO fcomi instruction. */
1768 pat_src
= XVECEXP (pat_src
, 0, 0);
1769 if (GET_CODE (pat_src
) != UNSPEC
1770 || XINT (pat_src
, 1) != UNSPEC_FNSTSW
)
1775 /* Combined fcomp+fnstsw generated for doing well with
1776 CSE. When optimizing this would have been broken
1779 pat_src
= XVECEXP (pat_src
, 0, 0);
1780 if (GET_CODE (pat_src
) != COMPARE
)
1783 compare_for_stack_reg (insn
, regstack
, pat_src
);
1792 /* This insn requires the top of stack to be the destination. */
1794 src1
= get_true_reg (&XEXP (pat_src
, 1));
1795 src2
= get_true_reg (&XEXP (pat_src
, 2));
1797 src1_note
= find_regno_note (insn
, REG_DEAD
, REGNO (*src1
));
1798 src2_note
= find_regno_note (insn
, REG_DEAD
, REGNO (*src2
));
1800 /* If the comparison operator is an FP comparison operator,
1801 it is handled correctly by compare_for_stack_reg () who
1802 will move the destination to the top of stack. But if the
1803 comparison operator is not an FP comparison operator, we
1804 have to handle it here. */
1805 if (get_hard_regnum (regstack
, *dest
) >= FIRST_STACK_REG
1806 && REGNO (*dest
) != regstack
->reg
[regstack
->top
])
1808 /* In case one of operands is the top of stack and the operands
1809 dies, it is safe to make it the destination operand by
1810 reversing the direction of cmove and avoid fxch. */
1811 if ((REGNO (*src1
) == regstack
->reg
[regstack
->top
]
1813 || (REGNO (*src2
) == regstack
->reg
[regstack
->top
]
1816 int idx1
= (get_hard_regnum (regstack
, *src1
)
1818 int idx2
= (get_hard_regnum (regstack
, *src2
)
1821 /* Make reg-stack believe that the operands are already
1822 swapped on the stack */
1823 regstack
->reg
[regstack
->top
- idx1
] = REGNO (*src2
);
1824 regstack
->reg
[regstack
->top
- idx2
] = REGNO (*src1
);
1826 /* Reverse condition to compensate the operand swap.
1827 i386 do have comparison always reversible. */
1828 PUT_CODE (XEXP (pat_src
, 0),
1829 reversed_comparison_code (XEXP (pat_src
, 0), insn
));
1832 emit_swap_insn (insn
, regstack
, *dest
);
1840 src_note
[1] = src1_note
;
1841 src_note
[2] = src2_note
;
1843 if (STACK_REG_P (*src1
))
1844 replace_reg (src1
, get_hard_regnum (regstack
, *src1
));
1845 if (STACK_REG_P (*src2
))
1846 replace_reg (src2
, get_hard_regnum (regstack
, *src2
));
1848 for (i
= 1; i
<= 2; i
++)
1851 int regno
= REGNO (XEXP (src_note
[i
], 0));
1853 /* If the register that dies is not at the top of
1854 stack, then move the top of stack to the dead reg */
1855 if (regno
!= regstack
->reg
[regstack
->top
])
1857 remove_regno_note (insn
, REG_DEAD
, regno
);
1858 emit_pop_insn (insn
, regstack
, XEXP (src_note
[i
], 0),
1862 /* Top of stack never dies, as it is the
1868 /* Make dest the top of stack. Add dest to regstack if
1870 if (get_hard_regnum (regstack
, *dest
) < FIRST_STACK_REG
)
1871 regstack
->reg
[++regstack
->top
] = REGNO (*dest
);
1872 SET_HARD_REG_BIT (regstack
->reg_set
, REGNO (*dest
));
1873 replace_reg (dest
, FIRST_STACK_REG
);
1886 return control_flow_insn_deleted
;
1889 /* Substitute hard regnums for any stack regs in INSN, which has
1890 N_INPUTS inputs and N_OUTPUTS outputs. REGSTACK is the stack info
1891 before the insn, and is updated with changes made here.
1893 There are several requirements and assumptions about the use of
1894 stack-like regs in asm statements. These rules are enforced by
1895 record_asm_stack_regs; see comments there for details. Any
1896 asm_operands left in the RTL at this point may be assume to meet the
1897 requirements, since record_asm_stack_regs removes any problem asm. */
1900 subst_asm_stack_regs (rtx insn
, stack regstack
)
1902 rtx body
= PATTERN (insn
);
1905 rtx
*note_reg
; /* Array of note contents */
1906 rtx
**note_loc
; /* Address of REG field of each note */
1907 enum reg_note
*note_kind
; /* The type of each note */
1909 rtx
*clobber_reg
= 0;
1910 rtx
**clobber_loc
= 0;
1912 struct stack_def temp_stack
;
1917 int n_inputs
, n_outputs
;
1919 if (! check_asm_stack_operands (insn
))
1922 /* Find out what the constraints required. If no constraint
1923 alternative matches, that is a compiler bug: we should have caught
1924 such an insn in check_asm_stack_operands. */
1925 extract_insn (insn
);
1926 constrain_operands (1);
1927 alt
= which_alternative
;
1929 preprocess_constraints ();
1931 n_inputs
= get_asm_operand_n_inputs (body
);
1932 n_outputs
= recog_data
.n_operands
- n_inputs
;
1937 /* Strip SUBREGs here to make the following code simpler. */
1938 for (i
= 0; i
< recog_data
.n_operands
; i
++)
1939 if (GET_CODE (recog_data
.operand
[i
]) == SUBREG
1940 && GET_CODE (SUBREG_REG (recog_data
.operand
[i
])) == REG
)
1942 recog_data
.operand_loc
[i
] = & SUBREG_REG (recog_data
.operand
[i
]);
1943 recog_data
.operand
[i
] = SUBREG_REG (recog_data
.operand
[i
]);
1946 /* Set up NOTE_REG, NOTE_LOC and NOTE_KIND. */
1948 for (i
= 0, note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
1951 note_reg
= alloca (i
* sizeof (rtx
));
1952 note_loc
= alloca (i
* sizeof (rtx
*));
1953 note_kind
= alloca (i
* sizeof (enum reg_note
));
1956 for (note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
1958 rtx reg
= XEXP (note
, 0);
1959 rtx
*loc
= & XEXP (note
, 0);
1961 if (GET_CODE (reg
) == SUBREG
&& GET_CODE (SUBREG_REG (reg
)) == REG
)
1963 loc
= & SUBREG_REG (reg
);
1964 reg
= SUBREG_REG (reg
);
1967 if (STACK_REG_P (reg
)
1968 && (REG_NOTE_KIND (note
) == REG_DEAD
1969 || REG_NOTE_KIND (note
) == REG_UNUSED
))
1971 note_reg
[n_notes
] = reg
;
1972 note_loc
[n_notes
] = loc
;
1973 note_kind
[n_notes
] = REG_NOTE_KIND (note
);
1978 /* Set up CLOBBER_REG and CLOBBER_LOC. */
1982 if (GET_CODE (body
) == PARALLEL
)
1984 clobber_reg
= alloca (XVECLEN (body
, 0) * sizeof (rtx
));
1985 clobber_loc
= alloca (XVECLEN (body
, 0) * sizeof (rtx
*));
1987 for (i
= 0; i
< XVECLEN (body
, 0); i
++)
1988 if (GET_CODE (XVECEXP (body
, 0, i
)) == CLOBBER
)
1990 rtx clobber
= XVECEXP (body
, 0, i
);
1991 rtx reg
= XEXP (clobber
, 0);
1992 rtx
*loc
= & XEXP (clobber
, 0);
1994 if (GET_CODE (reg
) == SUBREG
&& GET_CODE (SUBREG_REG (reg
)) == REG
)
1996 loc
= & SUBREG_REG (reg
);
1997 reg
= SUBREG_REG (reg
);
2000 if (STACK_REG_P (reg
))
2002 clobber_reg
[n_clobbers
] = reg
;
2003 clobber_loc
[n_clobbers
] = loc
;
2009 temp_stack
= *regstack
;
2011 /* Put the input regs into the desired place in TEMP_STACK. */
2013 for (i
= n_outputs
; i
< n_outputs
+ n_inputs
; i
++)
2014 if (STACK_REG_P (recog_data
.operand
[i
])
2015 && reg_class_subset_p (recog_op_alt
[i
][alt
].class,
2017 && recog_op_alt
[i
][alt
].class != FLOAT_REGS
)
2019 /* If an operand needs to be in a particular reg in
2020 FLOAT_REGS, the constraint was either 't' or 'u'. Since
2021 these constraints are for single register classes, and
2022 reload guaranteed that operand[i] is already in that class,
2023 we can just use REGNO (recog_data.operand[i]) to know which
2024 actual reg this operand needs to be in. */
2026 int regno
= get_hard_regnum (&temp_stack
, recog_data
.operand
[i
]);
2031 if ((unsigned int) regno
!= REGNO (recog_data
.operand
[i
]))
2033 /* recog_data.operand[i] is not in the right place. Find
2034 it and swap it with whatever is already in I's place.
2035 K is where recog_data.operand[i] is now. J is where it
2039 k
= temp_stack
.top
- (regno
- FIRST_STACK_REG
);
2041 - (REGNO (recog_data
.operand
[i
]) - FIRST_STACK_REG
));
2043 temp
= temp_stack
.reg
[k
];
2044 temp_stack
.reg
[k
] = temp_stack
.reg
[j
];
2045 temp_stack
.reg
[j
] = temp
;
2049 /* Emit insns before INSN to make sure the reg-stack is in the right
2052 change_stack (insn
, regstack
, &temp_stack
, EMIT_BEFORE
);
2054 /* Make the needed input register substitutions. Do death notes and
2055 clobbers too, because these are for inputs, not outputs. */
2057 for (i
= n_outputs
; i
< n_outputs
+ n_inputs
; i
++)
2058 if (STACK_REG_P (recog_data
.operand
[i
]))
2060 int regnum
= get_hard_regnum (regstack
, recog_data
.operand
[i
]);
2065 replace_reg (recog_data
.operand_loc
[i
], regnum
);
2068 for (i
= 0; i
< n_notes
; i
++)
2069 if (note_kind
[i
] == REG_DEAD
)
2071 int regnum
= get_hard_regnum (regstack
, note_reg
[i
]);
2076 replace_reg (note_loc
[i
], regnum
);
2079 for (i
= 0; i
< n_clobbers
; i
++)
2081 /* It's OK for a CLOBBER to reference a reg that is not live.
2082 Don't try to replace it in that case. */
2083 int regnum
= get_hard_regnum (regstack
, clobber_reg
[i
]);
2087 /* Sigh - clobbers always have QImode. But replace_reg knows
2088 that these regs can't be MODE_INT and will abort. Just put
2089 the right reg there without calling replace_reg. */
2091 *clobber_loc
[i
] = FP_MODE_REG (regnum
, DFmode
);
2095 /* Now remove from REGSTACK any inputs that the asm implicitly popped. */
2097 for (i
= n_outputs
; i
< n_outputs
+ n_inputs
; i
++)
2098 if (STACK_REG_P (recog_data
.operand
[i
]))
2100 /* An input reg is implicitly popped if it is tied to an
2101 output, or if there is a CLOBBER for it. */
2104 for (j
= 0; j
< n_clobbers
; j
++)
2105 if (operands_match_p (clobber_reg
[j
], recog_data
.operand
[i
]))
2108 if (j
< n_clobbers
|| recog_op_alt
[i
][alt
].matches
>= 0)
2110 /* recog_data.operand[i] might not be at the top of stack.
2111 But that's OK, because all we need to do is pop the
2112 right number of regs off of the top of the reg-stack.
2113 record_asm_stack_regs guaranteed that all implicitly
2114 popped regs were grouped at the top of the reg-stack. */
2116 CLEAR_HARD_REG_BIT (regstack
->reg_set
,
2117 regstack
->reg
[regstack
->top
]);
2122 /* Now add to REGSTACK any outputs that the asm implicitly pushed.
2123 Note that there isn't any need to substitute register numbers.
2124 ??? Explain why this is true. */
2126 for (i
= LAST_STACK_REG
; i
>= FIRST_STACK_REG
; i
--)
2128 /* See if there is an output for this hard reg. */
2131 for (j
= 0; j
< n_outputs
; j
++)
2132 if (STACK_REG_P (recog_data
.operand
[j
])
2133 && REGNO (recog_data
.operand
[j
]) == (unsigned) i
)
2135 regstack
->reg
[++regstack
->top
] = i
;
2136 SET_HARD_REG_BIT (regstack
->reg_set
, i
);
2141 /* Now emit a pop insn for any REG_UNUSED output, or any REG_DEAD
2142 input that the asm didn't implicitly pop. If the asm didn't
2143 implicitly pop an input reg, that reg will still be live.
2145 Note that we can't use find_regno_note here: the register numbers
2146 in the death notes have already been substituted. */
2148 for (i
= 0; i
< n_outputs
; i
++)
2149 if (STACK_REG_P (recog_data
.operand
[i
]))
2153 for (j
= 0; j
< n_notes
; j
++)
2154 if (REGNO (recog_data
.operand
[i
]) == REGNO (note_reg
[j
])
2155 && note_kind
[j
] == REG_UNUSED
)
2157 insn
= emit_pop_insn (insn
, regstack
, recog_data
.operand
[i
],
2163 for (i
= n_outputs
; i
< n_outputs
+ n_inputs
; i
++)
2164 if (STACK_REG_P (recog_data
.operand
[i
]))
2168 for (j
= 0; j
< n_notes
; j
++)
2169 if (REGNO (recog_data
.operand
[i
]) == REGNO (note_reg
[j
])
2170 && note_kind
[j
] == REG_DEAD
2171 && TEST_HARD_REG_BIT (regstack
->reg_set
,
2172 REGNO (recog_data
.operand
[i
])))
2174 insn
= emit_pop_insn (insn
, regstack
, recog_data
.operand
[i
],
2181 /* Substitute stack hard reg numbers for stack virtual registers in
2182 INSN. Non-stack register numbers are not changed. REGSTACK is the
2183 current stack content. Insns may be emitted as needed to arrange the
2184 stack for the 387 based on the contents of the insn. Return whether
2185 a control flow insn was deleted in the process. */
2188 subst_stack_regs (rtx insn
, stack regstack
)
2190 rtx
*note_link
, note
;
2191 bool control_flow_insn_deleted
= false;
2194 if (GET_CODE (insn
) == CALL_INSN
)
2196 int top
= regstack
->top
;
2198 /* If there are any floating point parameters to be passed in
2199 registers for this call, make sure they are in the right
2204 straighten_stack (PREV_INSN (insn
), regstack
);
2206 /* Now mark the arguments as dead after the call. */
2208 while (regstack
->top
>= 0)
2210 CLEAR_HARD_REG_BIT (regstack
->reg_set
, FIRST_STACK_REG
+ regstack
->top
);
2216 /* Do the actual substitution if any stack regs are mentioned.
2217 Since we only record whether entire insn mentions stack regs, and
2218 subst_stack_regs_pat only works for patterns that contain stack regs,
2219 we must check each pattern in a parallel here. A call_value_pop could
2222 if (stack_regs_mentioned (insn
))
2224 int n_operands
= asm_noperands (PATTERN (insn
));
2225 if (n_operands
>= 0)
2227 /* This insn is an `asm' with operands. Decode the operands,
2228 decide how many are inputs, and do register substitution.
2229 Any REG_UNUSED notes will be handled by subst_asm_stack_regs. */
2231 subst_asm_stack_regs (insn
, regstack
);
2232 return control_flow_insn_deleted
;
2235 if (GET_CODE (PATTERN (insn
)) == PARALLEL
)
2236 for (i
= 0; i
< XVECLEN (PATTERN (insn
), 0); i
++)
2238 if (stack_regs_mentioned_p (XVECEXP (PATTERN (insn
), 0, i
)))
2239 control_flow_insn_deleted
2240 |= subst_stack_regs_pat (insn
, regstack
,
2241 XVECEXP (PATTERN (insn
), 0, i
));
2244 control_flow_insn_deleted
2245 |= subst_stack_regs_pat (insn
, regstack
, PATTERN (insn
));
2248 /* subst_stack_regs_pat may have deleted a no-op insn. If so, any
2249 REG_UNUSED will already have been dealt with, so just return. */
2251 if (GET_CODE (insn
) == NOTE
|| INSN_DELETED_P (insn
))
2252 return control_flow_insn_deleted
;
2254 /* If there is a REG_UNUSED note on a stack register on this insn,
2255 the indicated reg must be popped. The REG_UNUSED note is removed,
2256 since the form of the newly emitted pop insn references the reg,
2257 making it no longer `unset'. */
2259 note_link
= ®_NOTES (insn
);
2260 for (note
= *note_link
; note
; note
= XEXP (note
, 1))
2261 if (REG_NOTE_KIND (note
) == REG_UNUSED
&& STACK_REG_P (XEXP (note
, 0)))
2263 *note_link
= XEXP (note
, 1);
2264 insn
= emit_pop_insn (insn
, regstack
, XEXP (note
, 0), EMIT_AFTER
);
2267 note_link
= &XEXP (note
, 1);
2269 return control_flow_insn_deleted
;
2272 /* Change the organization of the stack so that it fits a new basic
2273 block. Some registers might have to be popped, but there can never be
2274 a register live in the new block that is not now live.
2276 Insert any needed insns before or after INSN, as indicated by
2277 WHERE. OLD is the original stack layout, and NEW is the desired
2278 form. OLD is updated to reflect the code emitted, ie, it will be
2279 the same as NEW upon return.
2281 This function will not preserve block_end[]. But that information
2282 is no longer needed once this has executed. */
2285 change_stack (rtx insn
, stack old
, stack
new, enum emit_where where
)
2290 /* We will be inserting new insns "backwards". If we are to insert
2291 after INSN, find the next insn, and insert before it. */
2293 if (where
== EMIT_AFTER
)
2295 if (current_block
&& current_block
->end
== insn
)
2297 insn
= NEXT_INSN (insn
);
2300 /* Pop any registers that are not needed in the new block. */
2302 for (reg
= old
->top
; reg
>= 0; reg
--)
2303 if (! TEST_HARD_REG_BIT (new->reg_set
, old
->reg
[reg
]))
2304 emit_pop_insn (insn
, old
, FP_MODE_REG (old
->reg
[reg
], DFmode
),
2309 /* If the new block has never been processed, then it can inherit
2310 the old stack order. */
2312 new->top
= old
->top
;
2313 memcpy (new->reg
, old
->reg
, sizeof (new->reg
));
2317 /* This block has been entered before, and we must match the
2318 previously selected stack order. */
2320 /* By now, the only difference should be the order of the stack,
2321 not their depth or liveliness. */
2323 GO_IF_HARD_REG_EQUAL (old
->reg_set
, new->reg_set
, win
);
2326 if (old
->top
!= new->top
)
2329 /* If the stack is not empty (new->top != -1), loop here emitting
2330 swaps until the stack is correct.
2332 The worst case number of swaps emitted is N + 2, where N is the
2333 depth of the stack. In some cases, the reg at the top of
2334 stack may be correct, but swapped anyway in order to fix
2335 other regs. But since we never swap any other reg away from
2336 its correct slot, this algorithm will converge. */
2341 /* Swap the reg at top of stack into the position it is
2342 supposed to be in, until the correct top of stack appears. */
2344 while (old
->reg
[old
->top
] != new->reg
[new->top
])
2346 for (reg
= new->top
; reg
>= 0; reg
--)
2347 if (new->reg
[reg
] == old
->reg
[old
->top
])
2353 emit_swap_insn (insn
, old
,
2354 FP_MODE_REG (old
->reg
[reg
], DFmode
));
2357 /* See if any regs remain incorrect. If so, bring an
2358 incorrect reg to the top of stack, and let the while loop
2361 for (reg
= new->top
; reg
>= 0; reg
--)
2362 if (new->reg
[reg
] != old
->reg
[reg
])
2364 emit_swap_insn (insn
, old
,
2365 FP_MODE_REG (old
->reg
[reg
], DFmode
));
2370 /* At this point there must be no differences. */
2372 for (reg
= old
->top
; reg
>= 0; reg
--)
2373 if (old
->reg
[reg
] != new->reg
[reg
])
2378 current_block
->end
= PREV_INSN (insn
);
2381 /* Print stack configuration. */
2384 print_stack (FILE *file
, stack s
)
2390 fprintf (file
, "uninitialized\n");
2391 else if (s
->top
== -1)
2392 fprintf (file
, "empty\n");
2397 for (i
= 0; i
<= s
->top
; ++i
)
2398 fprintf (file
, "%d ", s
->reg
[i
]);
2399 fputs ("]\n", file
);
2403 /* This function was doing life analysis. We now let the regular live
2404 code do it's job, so we only need to check some extra invariants
2405 that reg-stack expects. Primary among these being that all registers
2406 are initialized before use.
2408 The function returns true when code was emitted to CFG edges and
2409 commit_edge_insertions needs to be called. */
2412 convert_regs_entry (void)
2418 FOR_EACH_BB_REVERSE (block
)
2420 block_info bi
= BLOCK_INFO (block
);
2423 /* Set current register status at last instruction `uninitialized'. */
2424 bi
->stack_in
.top
= -2;
2426 /* Copy live_at_end and live_at_start into temporaries. */
2427 for (reg
= FIRST_STACK_REG
; reg
<= LAST_STACK_REG
; reg
++)
2429 if (REGNO_REG_SET_P (block
->global_live_at_end
, reg
))
2430 SET_HARD_REG_BIT (bi
->out_reg_set
, reg
);
2431 if (REGNO_REG_SET_P (block
->global_live_at_start
, reg
))
2432 SET_HARD_REG_BIT (bi
->stack_in
.reg_set
, reg
);
2436 /* Load something into each stack register live at function entry.
2437 Such live registers can be caused by uninitialized variables or
2438 functions not returning values on all paths. In order to keep
2439 the push/pop code happy, and to not scrog the register stack, we
2440 must put something in these registers. Use a QNaN.
2442 Note that we are inserting converted code here. This code is
2443 never seen by the convert_regs pass. */
2445 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2447 basic_block block
= e
->dest
;
2448 block_info bi
= BLOCK_INFO (block
);
2451 for (reg
= LAST_STACK_REG
; reg
>= FIRST_STACK_REG
; --reg
)
2452 if (TEST_HARD_REG_BIT (bi
->stack_in
.reg_set
, reg
))
2456 bi
->stack_in
.reg
[++top
] = reg
;
2458 init
= gen_rtx_SET (VOIDmode
,
2459 FP_MODE_REG (FIRST_STACK_REG
, SFmode
),
2461 insert_insn_on_edge (init
, e
);
2465 bi
->stack_in
.top
= top
;
2471 /* Construct the desired stack for function exit. This will either
2472 be `empty', or the function return value at top-of-stack. */
2475 convert_regs_exit (void)
2477 int value_reg_low
, value_reg_high
;
2481 retvalue
= stack_result (current_function_decl
);
2482 value_reg_low
= value_reg_high
= -1;
2485 value_reg_low
= REGNO (retvalue
);
2486 value_reg_high
= value_reg_low
2487 + HARD_REGNO_NREGS (value_reg_low
, GET_MODE (retvalue
)) - 1;
2490 output_stack
= &BLOCK_INFO (EXIT_BLOCK_PTR
)->stack_in
;
2491 if (value_reg_low
== -1)
2492 output_stack
->top
= -1;
2497 output_stack
->top
= value_reg_high
- value_reg_low
;
2498 for (reg
= value_reg_low
; reg
<= value_reg_high
; ++reg
)
2500 output_stack
->reg
[value_reg_high
- reg
] = reg
;
2501 SET_HARD_REG_BIT (output_stack
->reg_set
, reg
);
2506 /* Adjust the stack of this block on exit to match the stack of the
2507 target block, or copy stack info into the stack of the successor
2508 of the successor hasn't been processed yet. */
2510 compensate_edge (edge e
, FILE *file
)
2512 basic_block block
= e
->src
, target
= e
->dest
;
2513 block_info bi
= BLOCK_INFO (block
);
2514 struct stack_def regstack
, tmpstack
;
2515 stack target_stack
= &BLOCK_INFO (target
)->stack_in
;
2518 current_block
= block
;
2519 regstack
= bi
->stack_out
;
2521 fprintf (file
, "Edge %d->%d: ", block
->index
, target
->index
);
2523 if (target_stack
->top
== -2)
2525 /* The target block hasn't had a stack order selected.
2526 We need merely ensure that no pops are needed. */
2527 for (reg
= regstack
.top
; reg
>= 0; --reg
)
2528 if (!TEST_HARD_REG_BIT (target_stack
->reg_set
, regstack
.reg
[reg
]))
2534 fprintf (file
, "new block; copying stack position\n");
2536 /* change_stack kills values in regstack. */
2537 tmpstack
= regstack
;
2539 change_stack (block
->end
, &tmpstack
, target_stack
, EMIT_AFTER
);
2544 fprintf (file
, "new block; pops needed\n");
2548 if (target_stack
->top
== regstack
.top
)
2550 for (reg
= target_stack
->top
; reg
>= 0; --reg
)
2551 if (target_stack
->reg
[reg
] != regstack
.reg
[reg
])
2557 fprintf (file
, "no changes needed\n");
2564 fprintf (file
, "correcting stack to ");
2565 print_stack (file
, target_stack
);
2569 /* Care for non-call EH edges specially. The normal return path have
2570 values in registers. These will be popped en masse by the unwind
2572 if ((e
->flags
& (EDGE_EH
| EDGE_ABNORMAL_CALL
)) == EDGE_EH
)
2573 target_stack
->top
= -1;
2575 /* Other calls may appear to have values live in st(0), but the
2576 abnormal return path will not have actually loaded the values. */
2577 else if (e
->flags
& EDGE_ABNORMAL_CALL
)
2579 /* Assert that the lifetimes are as we expect -- one value
2580 live at st(0) on the end of the source block, and no
2581 values live at the beginning of the destination block. */
2584 CLEAR_HARD_REG_SET (tmp
);
2585 GO_IF_HARD_REG_EQUAL (target_stack
->reg_set
, tmp
, eh1
);
2589 /* We are sure that there is st(0) live, otherwise we won't compensate.
2590 For complex return values, we may have st(1) live as well. */
2591 SET_HARD_REG_BIT (tmp
, FIRST_STACK_REG
);
2592 if (TEST_HARD_REG_BIT (regstack
.reg_set
, FIRST_STACK_REG
+ 1))
2593 SET_HARD_REG_BIT (tmp
, FIRST_STACK_REG
+ 1);
2594 GO_IF_HARD_REG_EQUAL (regstack
.reg_set
, tmp
, eh2
);
2598 target_stack
->top
= -1;
2601 /* It is better to output directly to the end of the block
2602 instead of to the edge, because emit_swap can do minimal
2603 insn scheduling. We can do this when there is only one
2604 edge out, and it is not abnormal. */
2605 else if (block
->succ
->succ_next
== NULL
&& !(e
->flags
& EDGE_ABNORMAL
))
2607 /* change_stack kills values in regstack. */
2608 tmpstack
= regstack
;
2610 change_stack (block
->end
, &tmpstack
, target_stack
,
2611 (GET_CODE (block
->end
) == JUMP_INSN
2612 ? EMIT_BEFORE
: EMIT_AFTER
));
2618 /* We don't support abnormal edges. Global takes care to
2619 avoid any live register across them, so we should never
2620 have to insert instructions on such edges. */
2621 if (e
->flags
& EDGE_ABNORMAL
)
2624 current_block
= NULL
;
2627 /* ??? change_stack needs some point to emit insns after. */
2628 after
= emit_note (NOTE_INSN_DELETED
);
2630 tmpstack
= regstack
;
2631 change_stack (after
, &tmpstack
, target_stack
, EMIT_BEFORE
);
2636 insert_insn_on_edge (seq
, e
);
2642 /* Convert stack register references in one block. */
2645 convert_regs_1 (FILE *file
, basic_block block
)
2647 struct stack_def regstack
;
2648 block_info bi
= BLOCK_INFO (block
);
2649 int deleted
, inserted
, reg
;
2651 edge e
, beste
= NULL
;
2652 bool control_flow_insn_deleted
= false;
2656 any_malformed_asm
= false;
2658 /* Find the edge we will copy stack from. It should be the most frequent
2659 one as it will get cheapest after compensation code is generated,
2660 if multiple such exists, take one with largest count, prefer critical
2661 one (as splitting critical edges is more expensive), or one with lowest
2662 index, to avoid random changes with different orders of the edges. */
2663 for (e
= block
->pred
; e
; e
= e
->pred_next
)
2665 if (e
->flags
& EDGE_DFS_BACK
)
2669 else if (EDGE_FREQUENCY (beste
) < EDGE_FREQUENCY (e
))
2671 else if (EDGE_FREQUENCY (beste
) > EDGE_FREQUENCY (e
))
2673 else if (beste
->count
< e
->count
)
2675 else if (beste
->count
> e
->count
)
2677 else if ((EDGE_CRITICAL_P (e
) != 0)
2678 != (EDGE_CRITICAL_P (beste
) != 0))
2680 if (EDGE_CRITICAL_P (e
))
2683 else if (e
->src
->index
< beste
->src
->index
)
2687 /* Initialize stack at block entry. */
2688 if (bi
->stack_in
.top
== -2)
2691 inserted
|= compensate_edge (beste
, file
);
2694 /* No predecessors. Create an arbitrary input stack. */
2697 bi
->stack_in
.top
= -1;
2698 for (reg
= LAST_STACK_REG
; reg
>= FIRST_STACK_REG
; --reg
)
2699 if (TEST_HARD_REG_BIT (bi
->stack_in
.reg_set
, reg
))
2700 bi
->stack_in
.reg
[++bi
->stack_in
.top
] = reg
;
2704 /* Entry blocks do have stack already initialized. */
2707 current_block
= block
;
2711 fprintf (file
, "\nBasic block %d\nInput stack: ", block
->index
);
2712 print_stack (file
, &bi
->stack_in
);
2715 /* Process all insns in this block. Keep track of NEXT so that we
2716 don't process insns emitted while substituting in INSN. */
2718 regstack
= bi
->stack_in
;
2722 next
= NEXT_INSN (insn
);
2724 /* Ensure we have not missed a block boundary. */
2727 if (insn
== block
->end
)
2730 /* Don't bother processing unless there is a stack reg
2731 mentioned or if it's a CALL_INSN. */
2732 if (stack_regs_mentioned (insn
)
2733 || GET_CODE (insn
) == CALL_INSN
)
2737 fprintf (file
, " insn %d input stack: ",
2739 print_stack (file
, ®stack
);
2741 control_flow_insn_deleted
|= subst_stack_regs (insn
, ®stack
);
2748 fprintf (file
, "Expected live registers [");
2749 for (reg
= FIRST_STACK_REG
; reg
<= LAST_STACK_REG
; ++reg
)
2750 if (TEST_HARD_REG_BIT (bi
->out_reg_set
, reg
))
2751 fprintf (file
, " %d", reg
);
2752 fprintf (file
, " ]\nOutput stack: ");
2753 print_stack (file
, ®stack
);
2757 if (GET_CODE (insn
) == JUMP_INSN
)
2758 insn
= PREV_INSN (insn
);
2760 /* If the function is declared to return a value, but it returns one
2761 in only some cases, some registers might come live here. Emit
2762 necessary moves for them. */
2764 for (reg
= FIRST_STACK_REG
; reg
<= LAST_STACK_REG
; ++reg
)
2766 if (TEST_HARD_REG_BIT (bi
->out_reg_set
, reg
)
2767 && ! TEST_HARD_REG_BIT (regstack
.reg_set
, reg
))
2773 fprintf (file
, "Emitting insn initializing reg %d\n",
2777 set
= gen_rtx_SET (VOIDmode
, FP_MODE_REG (reg
, SFmode
),
2779 insn
= emit_insn_after (set
, insn
);
2780 control_flow_insn_deleted
|= subst_stack_regs (insn
, ®stack
);
2784 /* Amongst the insns possibly deleted during the substitution process above,
2785 might have been the only trapping insn in the block. We purge the now
2786 possibly dead EH edges here to avoid an ICE from fixup_abnormal_edges,
2787 called at the end of convert_regs. The order in which we process the
2788 blocks ensures that we never delete an already processed edge.
2790 Note that, at this point, the CFG may have been damaged by the emission
2791 of instructions after an abnormal call, which moves the basic block end
2792 (and is the reason why we call fixup_abnormal_edges later). So we must
2793 be sure that the trapping insn has been deleted before trying to purge
2794 dead edges, otherwise we risk purging valid edges.
2796 ??? We are normally supposed not to delete trapping insns, so we pretend
2797 that the insns deleted above don't actually trap. It would have been
2798 better to detect this earlier and avoid creating the EH edge in the first
2799 place, still, but we don't have enough information at that time. */
2801 if (control_flow_insn_deleted
)
2802 purge_dead_edges (block
);
2804 /* Something failed if the stack lives don't match. If we had malformed
2805 asms, we zapped the instruction itself, but that didn't produce the
2806 same pattern of register kills as before. */
2807 GO_IF_HARD_REG_EQUAL (regstack
.reg_set
, bi
->out_reg_set
, win
);
2808 if (!any_malformed_asm
)
2811 bi
->stack_out
= regstack
;
2813 /* Compensate the back edges, as those wasn't visited yet. */
2814 for (e
= block
->succ
; e
; e
= e
->succ_next
)
2816 if (e
->flags
& EDGE_DFS_BACK
2817 || (e
->dest
== EXIT_BLOCK_PTR
))
2819 if (!BLOCK_INFO (e
->dest
)->done
2820 && e
->dest
!= block
)
2822 inserted
|= compensate_edge (e
, file
);
2825 for (e
= block
->pred
; e
; e
= e
->pred_next
)
2827 if (e
!= beste
&& !(e
->flags
& EDGE_DFS_BACK
)
2828 && e
->src
!= ENTRY_BLOCK_PTR
)
2830 if (!BLOCK_INFO (e
->src
)->done
)
2832 inserted
|= compensate_edge (e
, file
);
2839 /* Convert registers in all blocks reachable from BLOCK. */
2842 convert_regs_2 (FILE *file
, basic_block block
)
2844 basic_block
*stack
, *sp
;
2847 /* We process the blocks in a top-down manner, in a way such that one block
2848 is only processed after all its predecessors. The number of predecessors
2849 of every block has already been computed. */
2851 stack
= xmalloc (sizeof (*stack
) * n_basic_blocks
);
2863 /* Processing BLOCK is achieved by convert_regs_1, which may purge
2864 some dead EH outgoing edge after the deletion of the trapping
2865 insn inside the block. Since the number of predecessors of
2866 BLOCK's successors was computed based on the initial edge set,
2867 we check the necessity to process some of these successors
2868 before such an edge deletion may happen. However, there is
2869 a pitfall: if BLOCK is the only predecessor of a successor and
2870 the edge between them happens to be deleted, the successor
2871 becomes unreachable and should not be processed. The problem
2872 is that there is no way to preventively detect this case so we
2873 stack the successor in all cases and hand over the task of
2874 fixing up the discrepancy to convert_regs_1. */
2876 for (e
= block
->succ
; e
; e
= e
->succ_next
)
2877 if (! (e
->flags
& EDGE_DFS_BACK
))
2879 BLOCK_INFO (e
->dest
)->predecessors
--;
2880 if (!BLOCK_INFO (e
->dest
)->predecessors
)
2884 inserted
|= convert_regs_1 (file
, block
);
2885 BLOCK_INFO (block
)->done
= 1;
2887 while (sp
!= stack
);
2892 /* Traverse all basic blocks in a function, converting the register
2893 references in each insn from the "flat" register file that gcc uses,
2894 to the stack-like registers the 387 uses. */
2897 convert_regs (FILE *file
)
2903 /* Initialize uninitialized registers on function entry. */
2904 inserted
= convert_regs_entry ();
2906 /* Construct the desired stack for function exit. */
2907 convert_regs_exit ();
2908 BLOCK_INFO (EXIT_BLOCK_PTR
)->done
= 1;
2910 /* ??? Future: process inner loops first, and give them arbitrary
2911 initial stacks which emit_swap_insn can modify. This ought to
2912 prevent double fxch that aften appears at the head of a loop. */
2914 /* Process all blocks reachable from all entry points. */
2915 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
2916 inserted
|= convert_regs_2 (file
, e
->dest
);
2918 /* ??? Process all unreachable blocks. Though there's no excuse
2919 for keeping these even when not optimizing. */
2922 block_info bi
= BLOCK_INFO (b
);
2925 inserted
|= convert_regs_2 (file
, b
);
2927 clear_aux_for_blocks ();
2929 fixup_abnormal_edges ();
2931 commit_edge_insertions ();
2938 #endif /* STACK_REGS */
2940 #include "gt-reg-stack.h"