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[/] [openrisc/] [trunk/] [gnu-stable/] [gcc-4.5.1/] [gcc/] [reg-stack.c] - Blame information for rev 826

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1 280 jeremybenn
/* Register to Stack convert for GNU compiler.
2
   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
3
   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
4
   Free Software Foundation, Inc.
5
 
6
   This file is part of GCC.
7
 
8
   GCC is free software; you can redistribute it and/or modify it
9
   under the terms of the GNU General Public License as published by
10
   the Free Software Foundation; either version 3, or (at your option)
11
   any later version.
12
 
13
   GCC is distributed in the hope that it will be useful, but WITHOUT
14
   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15
   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
16
   License for more details.
17
 
18
   You should have received a copy of the GNU General Public License
19
   along with GCC; see the file COPYING3.  If not see
20
   <http://www.gnu.org/licenses/>.  */
21
 
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.
24
 
25
   * The form of the input:
26
 
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.
36
 
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.
44
 
45
   * The form of the output:
46
 
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.
52
 
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.
55
 
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.
59
 
60
   A store insn is a SET whose SET_DEST is FIRST_STACK_REG, and whose
61
   SET_SRC is REG or MEM.
62
 
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.
66
 
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
70
   stack.
71
 
72
   * Methodology:
73
 
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.
77
 
78
   * asm_operands:
79
 
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
82
   stack-like regs:
83
 
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.
87
 
88
        An input reg that is implicitly popped by the asm must be
89
        explicitly clobbered, unless it is constrained to match an
90
        output operand.
91
 
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
97
      up".
98
 
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.
101
 
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:
104
 
105
                asm ("foo" : "=t" (a) : "f" (b));
106
 
107
      This asm says that input B is not popped by the asm, and that
108
      the asm pushes a result onto the reg-stack, i.e., the stack is one
109
      deeper after the asm than it was before.  But, it is possible that
110
      reload will think that it can use the same reg for both the input and
111
      the output, if input B dies in this insn.
112
 
113
        If any input operand uses the "f" constraint, all output reg
114
        constraints must use the "&" earlyclobber.
115
 
116
      The asm above would be written as
117
 
118
                asm ("foo" : "=&t" (a) : "f" (b));
119
 
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.
124
 
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.
128
 
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.
133
 
134
        Output operands must start at the top of the reg-stack: output
135
        operands may not "skip" a reg.
136
 
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.
140
 
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.
143
 
144
        asm ("fsincos" : "=t" (cos), "=u" (sin) : "0" (inp));
145
 
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.
149
 
150
        asm ("fyl2xp1" : "=t" (result) : "0" (x), "u" (y) : "st(1)");
151
 
152
*/
153
 
154
#include "config.h"
155
#include "system.h"
156
#include "coretypes.h"
157
#include "tm.h"
158
#include "tree.h"
159
#include "rtl.h"
160
#include "tm_p.h"
161
#include "function.h"
162
#include "insn-config.h"
163
#include "regs.h"
164
#include "hard-reg-set.h"
165
#include "flags.h"
166
#include "toplev.h"
167
#include "recog.h"
168
#include "output.h"
169
#include "basic-block.h"
170
#include "cfglayout.h"
171
#include "varray.h"
172
#include "reload.h"
173
#include "ggc.h"
174
#include "timevar.h"
175
#include "tree-pass.h"
176
#include "target.h"
177
#include "df.h"
178
#include "vecprim.h"
179
 
180
#ifdef STACK_REGS
181
 
182
/* We use this array to cache info about insns, because otherwise we
183
   spend too much time in stack_regs_mentioned_p.
184
 
185
   Indexed by insn UIDs.  A value of zero is uninitialized, one indicates
186
   the insn uses stack registers, two indicates the insn does not use
187
   stack registers.  */
188
static VEC(char,heap) *stack_regs_mentioned_data;
189
 
190
#define REG_STACK_SIZE (LAST_STACK_REG - FIRST_STACK_REG + 1)
191
 
192
int regstack_completed = 0;
193
 
194
/* This is the basic stack record.  TOP is an index into REG[] such
195
   that REG[TOP] is the top of stack.  If TOP is -1 the stack is empty.
196
 
197
   If TOP is -2, REG[] is not yet initialized.  Stack initialization
198
   consists of placing each live reg in array `reg' and setting `top'
199
   appropriately.
200
 
201
   REG_SET indicates which registers are live.  */
202
 
203
typedef struct stack_def
204
{
205
  int top;                      /* index to top stack element */
206
  HARD_REG_SET reg_set;         /* set of live registers */
207
  unsigned char reg[REG_STACK_SIZE];/* register - stack mapping */
208
} *stack;
209
 
210
/* This is used to carry information about basic blocks.  It is
211
   attached to the AUX field of the standard CFG block.  */
212
 
213
typedef struct block_info_def
214
{
215
  struct stack_def stack_in;    /* Input stack configuration.  */
216
  struct stack_def stack_out;   /* Output stack configuration.  */
217
  HARD_REG_SET out_reg_set;     /* Stack regs live on output.  */
218
  int done;                     /* True if block already converted.  */
219
  int predecessors;             /* Number of predecessors that need
220
                                   to be visited.  */
221
} *block_info;
222
 
223
#define BLOCK_INFO(B)   ((block_info) (B)->aux)
224
 
225
/* Passed to change_stack to indicate where to emit insns.  */
226
enum emit_where
227
{
228
  EMIT_AFTER,
229
  EMIT_BEFORE
230
};
231
 
232
/* The block we're currently working on.  */
233
static basic_block current_block;
234
 
235
/* In the current_block, whether we're processing the first register
236
   stack or call instruction, i.e. the regstack is currently the
237
   same as BLOCK_INFO(current_block)->stack_in.  */
238
static bool starting_stack_p;
239
 
240
/* This is the register file for all register after conversion.  */
241
static rtx
242
  FP_mode_reg[LAST_STACK_REG+1-FIRST_STACK_REG][(int) MAX_MACHINE_MODE];
243
 
244
#define FP_MODE_REG(regno,mode) \
245
  (FP_mode_reg[(regno)-FIRST_STACK_REG][(int) (mode)])
246
 
247
/* Used to initialize uninitialized registers.  */
248
static rtx not_a_num;
249
 
250
/* Forward declarations */
251
 
252
static int stack_regs_mentioned_p (const_rtx pat);
253
static void pop_stack (stack, int);
254
static rtx *get_true_reg (rtx *);
255
 
256
static int check_asm_stack_operands (rtx);
257
static void get_asm_operands_in_out (rtx, int *, int *);
258
static rtx stack_result (tree);
259
static void replace_reg (rtx *, int);
260
static void remove_regno_note (rtx, enum reg_note, unsigned int);
261
static int get_hard_regnum (stack, rtx);
262
static rtx emit_pop_insn (rtx, stack, rtx, enum emit_where);
263
static void swap_to_top(rtx, stack, rtx, rtx);
264
static bool move_for_stack_reg (rtx, stack, rtx);
265
static bool move_nan_for_stack_reg (rtx, stack, rtx);
266
static int swap_rtx_condition_1 (rtx);
267
static int swap_rtx_condition (rtx);
268
static void compare_for_stack_reg (rtx, stack, rtx);
269
static bool subst_stack_regs_pat (rtx, stack, rtx);
270
static void subst_asm_stack_regs (rtx, stack);
271
static bool subst_stack_regs (rtx, stack);
272
static void change_stack (rtx, stack, stack, enum emit_where);
273
static void print_stack (FILE *, stack);
274
static rtx next_flags_user (rtx);
275
 
276
/* Return nonzero if any stack register is mentioned somewhere within PAT.  */
277
 
278
static int
279
stack_regs_mentioned_p (const_rtx pat)
280
{
281
  const char *fmt;
282
  int i;
283
 
284
  if (STACK_REG_P (pat))
285
    return 1;
286
 
287
  fmt = GET_RTX_FORMAT (GET_CODE (pat));
288
  for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
289
    {
290
      if (fmt[i] == 'E')
291
        {
292
          int j;
293
 
294
          for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
295
            if (stack_regs_mentioned_p (XVECEXP (pat, i, j)))
296
              return 1;
297
        }
298
      else if (fmt[i] == 'e' && stack_regs_mentioned_p (XEXP (pat, i)))
299
        return 1;
300
    }
301
 
302
  return 0;
303
}
304
 
305
/* Return nonzero if INSN mentions stacked registers, else return zero.  */
306
 
307
int
308
stack_regs_mentioned (const_rtx insn)
309
{
310
  unsigned int uid, max;
311
  int test;
312
 
313
  if (! INSN_P (insn) || !stack_regs_mentioned_data)
314
    return 0;
315
 
316
  uid = INSN_UID (insn);
317
  max = VEC_length (char, stack_regs_mentioned_data);
318
  if (uid >= max)
319
    {
320
      /* Allocate some extra size to avoid too many reallocs, but
321
         do not grow too quickly.  */
322
      max = uid + uid / 20 + 1;
323
      VEC_safe_grow_cleared (char, heap, stack_regs_mentioned_data, max);
324
    }
325
 
326
  test = VEC_index (char, stack_regs_mentioned_data, uid);
327
  if (test == 0)
328
    {
329
      /* This insn has yet to be examined.  Do so now.  */
330
      test = stack_regs_mentioned_p (PATTERN (insn)) ? 1 : 2;
331
      VEC_replace (char, stack_regs_mentioned_data, uid, test);
332
    }
333
 
334
  return test == 1;
335
}
336
 
337
static rtx ix86_flags_rtx;
338
 
339
static rtx
340
next_flags_user (rtx insn)
341
{
342
  /* Search forward looking for the first use of this value.
343
     Stop at block boundaries.  */
344
 
345
  while (insn != BB_END (current_block))
346
    {
347
      insn = NEXT_INSN (insn);
348
 
349
      if (INSN_P (insn) && reg_mentioned_p (ix86_flags_rtx, PATTERN (insn)))
350
        return insn;
351
 
352
      if (CALL_P (insn))
353
        return NULL_RTX;
354
    }
355
  return NULL_RTX;
356
}
357
 
358
/* Reorganize the stack into ascending numbers, before this insn.  */
359
 
360
static void
361
straighten_stack (rtx insn, stack regstack)
362
{
363
  struct stack_def temp_stack;
364
  int top;
365
 
366
  /* If there is only a single register on the stack, then the stack is
367
     already in increasing order and no reorganization is needed.
368
 
369
     Similarly if the stack is empty.  */
370
  if (regstack->top <= 0)
371
    return;
372
 
373
  COPY_HARD_REG_SET (temp_stack.reg_set, regstack->reg_set);
374
 
375
  for (top = temp_stack.top = regstack->top; top >= 0; top--)
376
    temp_stack.reg[top] = FIRST_STACK_REG + temp_stack.top - top;
377
 
378
  change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
379
}
380
 
381
/* Pop a register from the stack.  */
382
 
383
static void
384
pop_stack (stack regstack, int regno)
385
{
386
  int top = regstack->top;
387
 
388
  CLEAR_HARD_REG_BIT (regstack->reg_set, regno);
389
  regstack->top--;
390
  /* If regno was not at the top of stack then adjust stack.  */
391
  if (regstack->reg [top] != regno)
392
    {
393
      int i;
394
      for (i = regstack->top; i >= 0; i--)
395
        if (regstack->reg [i] == regno)
396
          {
397
            int j;
398
            for (j = i; j < top; j++)
399
              regstack->reg [j] = regstack->reg [j + 1];
400
            break;
401
          }
402
    }
403
}
404
 
405
/* Return a pointer to the REG expression within PAT.  If PAT is not a
406
   REG, possible enclosed by a conversion rtx, return the inner part of
407
   PAT that stopped the search.  */
408
 
409
static rtx *
410
get_true_reg (rtx *pat)
411
{
412
  for (;;)
413
    switch (GET_CODE (*pat))
414
      {
415
      case SUBREG:
416
        /* Eliminate FP subregister accesses in favor of the
417
           actual FP register in use.  */
418
        {
419
          rtx subreg;
420
          if (FP_REG_P (subreg = SUBREG_REG (*pat)))
421
            {
422
              int regno_off = subreg_regno_offset (REGNO (subreg),
423
                                                   GET_MODE (subreg),
424
                                                   SUBREG_BYTE (*pat),
425
                                                   GET_MODE (*pat));
426
              *pat = FP_MODE_REG (REGNO (subreg) + regno_off,
427
                                  GET_MODE (subreg));
428
              return pat;
429
            }
430
        }
431
      case FLOAT:
432
      case FIX:
433
      case FLOAT_EXTEND:
434
        pat = & XEXP (*pat, 0);
435
        break;
436
 
437
      case UNSPEC:
438
        if (XINT (*pat, 1) == UNSPEC_TRUNC_NOOP)
439
          pat = & XVECEXP (*pat, 0, 0);
440
        return pat;
441
 
442
      case FLOAT_TRUNCATE:
443
        if (!flag_unsafe_math_optimizations)
444
          return pat;
445
        pat = & XEXP (*pat, 0);
446
        break;
447
 
448
      default:
449
        return pat;
450
      }
451
}
452
 
453
/* Set if we find any malformed asms in a block.  */
454
static bool any_malformed_asm;
455
 
456
/* There are many rules that an asm statement for stack-like regs must
457
   follow.  Those rules are explained at the top of this file: the rule
458
   numbers below refer to that explanation.  */
459
 
460
static int
461
check_asm_stack_operands (rtx insn)
462
{
463
  int i;
464
  int n_clobbers;
465
  int malformed_asm = 0;
466
  rtx body = PATTERN (insn);
467
 
468
  char reg_used_as_output[FIRST_PSEUDO_REGISTER];
469
  char implicitly_dies[FIRST_PSEUDO_REGISTER];
470
  int alt;
471
 
472
  rtx *clobber_reg = 0;
473
  int n_inputs, n_outputs;
474
 
475
  /* Find out what the constraints require.  If no constraint
476
     alternative matches, this asm is malformed.  */
477
  extract_insn (insn);
478
  constrain_operands (1);
479
  alt = which_alternative;
480
 
481
  preprocess_constraints ();
482
 
483
  get_asm_operands_in_out (body, &n_outputs, &n_inputs);
484
 
485
  if (alt < 0)
486
    {
487
      malformed_asm = 1;
488
      /* Avoid further trouble with this insn.  */
489
      PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
490
      return 0;
491
    }
492
 
493
  /* Strip SUBREGs here to make the following code simpler.  */
494
  for (i = 0; i < recog_data.n_operands; i++)
495
    if (GET_CODE (recog_data.operand[i]) == SUBREG
496
        && REG_P (SUBREG_REG (recog_data.operand[i])))
497
      recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
498
 
499
  /* Set up CLOBBER_REG.  */
500
 
501
  n_clobbers = 0;
502
 
503
  if (GET_CODE (body) == PARALLEL)
504
    {
505
      clobber_reg = XALLOCAVEC (rtx, XVECLEN (body, 0));
506
 
507
      for (i = 0; i < XVECLEN (body, 0); i++)
508
        if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
509
          {
510
            rtx clobber = XVECEXP (body, 0, i);
511
            rtx reg = XEXP (clobber, 0);
512
 
513
            if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
514
              reg = SUBREG_REG (reg);
515
 
516
            if (STACK_REG_P (reg))
517
              {
518
                clobber_reg[n_clobbers] = reg;
519
                n_clobbers++;
520
              }
521
          }
522
    }
523
 
524
  /* Enforce rule #4: Output operands must specifically indicate which
525
     reg an output appears in after an asm.  "=f" is not allowed: the
526
     operand constraints must select a class with a single reg.
527
 
528
     Also enforce rule #5: Output operands must start at the top of
529
     the reg-stack: output operands may not "skip" a reg.  */
530
 
531
  memset (reg_used_as_output, 0, sizeof (reg_used_as_output));
532
  for (i = 0; i < n_outputs; i++)
533
    if (STACK_REG_P (recog_data.operand[i]))
534
      {
535
        if (reg_class_size[(int) recog_op_alt[i][alt].cl] != 1)
536
          {
537
            error_for_asm (insn, "output constraint %d must specify a single register", i);
538
            malformed_asm = 1;
539
          }
540
        else
541
          {
542
            int j;
543
 
544
            for (j = 0; j < n_clobbers; j++)
545
              if (REGNO (recog_data.operand[i]) == REGNO (clobber_reg[j]))
546
                {
547
                  error_for_asm (insn, "output constraint %d cannot be specified together with \"%s\" clobber",
548
                                 i, reg_names [REGNO (clobber_reg[j])]);
549
                  malformed_asm = 1;
550
                  break;
551
                }
552
            if (j == n_clobbers)
553
              reg_used_as_output[REGNO (recog_data.operand[i])] = 1;
554
          }
555
      }
556
 
557
 
558
  /* Search for first non-popped reg.  */
559
  for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
560
    if (! reg_used_as_output[i])
561
      break;
562
 
563
  /* If there are any other popped regs, that's an error.  */
564
  for (; i < LAST_STACK_REG + 1; i++)
565
    if (reg_used_as_output[i])
566
      break;
567
 
568
  if (i != LAST_STACK_REG + 1)
569
    {
570
      error_for_asm (insn, "output regs must be grouped at top of stack");
571
      malformed_asm = 1;
572
    }
573
 
574
  /* Enforce rule #2: All implicitly popped input regs must be closer
575
     to the top of the reg-stack than any input that is not implicitly
576
     popped.  */
577
 
578
  memset (implicitly_dies, 0, sizeof (implicitly_dies));
579
  for (i = n_outputs; i < n_outputs + n_inputs; i++)
580
    if (STACK_REG_P (recog_data.operand[i]))
581
      {
582
        /* An input reg is implicitly popped if it is tied to an
583
           output, or if there is a CLOBBER for it.  */
584
        int j;
585
 
586
        for (j = 0; j < n_clobbers; j++)
587
          if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
588
            break;
589
 
590
        if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
591
          implicitly_dies[REGNO (recog_data.operand[i])] = 1;
592
      }
593
 
594
  /* Search for first non-popped reg.  */
595
  for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
596
    if (! implicitly_dies[i])
597
      break;
598
 
599
  /* If there are any other popped regs, that's an error.  */
600
  for (; i < LAST_STACK_REG + 1; i++)
601
    if (implicitly_dies[i])
602
      break;
603
 
604
  if (i != LAST_STACK_REG + 1)
605
    {
606
      error_for_asm (insn,
607
                     "implicitly popped regs must be grouped at top of stack");
608
      malformed_asm = 1;
609
    }
610
 
611
  /* Enforce rule #3: If any input operand uses the "f" constraint, all
612
     output constraints must use the "&" earlyclobber.
613
 
614
     ??? Detect this more deterministically by having constrain_asm_operands
615
     record any earlyclobber.  */
616
 
617
  for (i = n_outputs; i < n_outputs + n_inputs; i++)
618
    if (recog_op_alt[i][alt].matches == -1)
619
      {
620
        int j;
621
 
622
        for (j = 0; j < n_outputs; j++)
623
          if (operands_match_p (recog_data.operand[j], recog_data.operand[i]))
624
            {
625
              error_for_asm (insn,
626
                             "output operand %d must use %<&%> constraint", j);
627
              malformed_asm = 1;
628
            }
629
      }
630
 
631
  if (malformed_asm)
632
    {
633
      /* Avoid further trouble with this insn.  */
634
      PATTERN (insn) = gen_rtx_USE (VOIDmode, const0_rtx);
635
      any_malformed_asm = true;
636
      return 0;
637
    }
638
 
639
  return 1;
640
}
641
 
642
/* Calculate the number of inputs and outputs in BODY, an
643
   asm_operands.  N_OPERANDS is the total number of operands, and
644
   N_INPUTS and N_OUTPUTS are pointers to ints into which the results are
645
   placed.  */
646
 
647
static void
648
get_asm_operands_in_out (rtx body, int *pout, int *pin)
649
{
650
  rtx asmop = extract_asm_operands (body);
651
 
652
  *pin = ASM_OPERANDS_INPUT_LENGTH (asmop);
653
  *pout = (recog_data.n_operands
654
           - ASM_OPERANDS_INPUT_LENGTH (asmop)
655
           - ASM_OPERANDS_LABEL_LENGTH (asmop));
656
}
657
 
658
/* If current function returns its result in an fp stack register,
659
   return the REG.  Otherwise, return 0.  */
660
 
661
static rtx
662
stack_result (tree decl)
663
{
664
  rtx result;
665
 
666
  /* If the value is supposed to be returned in memory, then clearly
667
     it is not returned in a stack register.  */
668
  if (aggregate_value_p (DECL_RESULT (decl), decl))
669
    return 0;
670
 
671
  result = DECL_RTL_IF_SET (DECL_RESULT (decl));
672
  if (result != 0)
673
    result = targetm.calls.function_value (TREE_TYPE (DECL_RESULT (decl)),
674
                                           decl, true);
675
 
676
  return result != 0 && STACK_REG_P (result) ? result : 0;
677
}
678
 
679
 
680
/*
681
 * This section deals with stack register substitution, and forms the second
682
 * pass over the RTL.
683
 */
684
 
685
/* Replace REG, which is a pointer to a stack reg RTX, with an RTX for
686
   the desired hard REGNO.  */
687
 
688
static void
689
replace_reg (rtx *reg, int regno)
690
{
691
  gcc_assert (IN_RANGE (regno, FIRST_STACK_REG, LAST_STACK_REG));
692
  gcc_assert (STACK_REG_P (*reg));
693
 
694
  gcc_assert (SCALAR_FLOAT_MODE_P (GET_MODE (*reg))
695
              || GET_MODE_CLASS (GET_MODE (*reg)) == MODE_COMPLEX_FLOAT);
696
 
697
  *reg = FP_MODE_REG (regno, GET_MODE (*reg));
698
}
699
 
700
/* Remove a note of type NOTE, which must be found, for register
701
   number REGNO from INSN.  Remove only one such note.  */
702
 
703
static void
704
remove_regno_note (rtx insn, enum reg_note note, unsigned int regno)
705
{
706
  rtx *note_link, this_rtx;
707
 
708
  note_link = &REG_NOTES (insn);
709
  for (this_rtx = *note_link; this_rtx; this_rtx = XEXP (this_rtx, 1))
710
    if (REG_NOTE_KIND (this_rtx) == note
711
        && REG_P (XEXP (this_rtx, 0)) && REGNO (XEXP (this_rtx, 0)) == regno)
712
      {
713
        *note_link = XEXP (this_rtx, 1);
714
        return;
715
      }
716
    else
717
      note_link = &XEXP (this_rtx, 1);
718
 
719
  gcc_unreachable ();
720
}
721
 
722
/* Find the hard register number of virtual register REG in REGSTACK.
723
   The hard register number is relative to the top of the stack.  -1 is
724
   returned if the register is not found.  */
725
 
726
static int
727
get_hard_regnum (stack regstack, rtx reg)
728
{
729
  int i;
730
 
731
  gcc_assert (STACK_REG_P (reg));
732
 
733
  for (i = regstack->top; i >= 0; i--)
734
    if (regstack->reg[i] == REGNO (reg))
735
      break;
736
 
737
  return i >= 0 ? (FIRST_STACK_REG + regstack->top - i) : -1;
738
}
739
 
740
/* Emit an insn to pop virtual register REG before or after INSN.
741
   REGSTACK is the stack state after INSN and is updated to reflect this
742
   pop.  WHEN is either emit_insn_before or emit_insn_after.  A pop insn
743
   is represented as a SET whose destination is the register to be popped
744
   and source is the top of stack.  A death note for the top of stack
745
   cases the movdf pattern to pop.  */
746
 
747
static rtx
748
emit_pop_insn (rtx insn, stack regstack, rtx reg, enum emit_where where)
749
{
750
  rtx pop_insn, pop_rtx;
751
  int hard_regno;
752
 
753
  /* For complex types take care to pop both halves.  These may survive in
754
     CLOBBER and USE expressions.  */
755
  if (COMPLEX_MODE_P (GET_MODE (reg)))
756
    {
757
      rtx reg1 = FP_MODE_REG (REGNO (reg), DFmode);
758
      rtx reg2 = FP_MODE_REG (REGNO (reg) + 1, DFmode);
759
 
760
      pop_insn = NULL_RTX;
761
      if (get_hard_regnum (regstack, reg1) >= 0)
762
        pop_insn = emit_pop_insn (insn, regstack, reg1, where);
763
      if (get_hard_regnum (regstack, reg2) >= 0)
764
        pop_insn = emit_pop_insn (insn, regstack, reg2, where);
765
      gcc_assert (pop_insn);
766
      return pop_insn;
767
    }
768
 
769
  hard_regno = get_hard_regnum (regstack, reg);
770
 
771
  gcc_assert (hard_regno >= FIRST_STACK_REG);
772
 
773
  pop_rtx = gen_rtx_SET (VOIDmode, FP_MODE_REG (hard_regno, DFmode),
774
                         FP_MODE_REG (FIRST_STACK_REG, DFmode));
775
 
776
  if (where == EMIT_AFTER)
777
    pop_insn = emit_insn_after (pop_rtx, insn);
778
  else
779
    pop_insn = emit_insn_before (pop_rtx, insn);
780
 
781
  add_reg_note (pop_insn, REG_DEAD, FP_MODE_REG (FIRST_STACK_REG, DFmode));
782
 
783
  regstack->reg[regstack->top - (hard_regno - FIRST_STACK_REG)]
784
    = regstack->reg[regstack->top];
785
  regstack->top -= 1;
786
  CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (reg));
787
 
788
  return pop_insn;
789
}
790
 
791
/* Emit an insn before or after INSN to swap virtual register REG with
792
   the top of stack.  REGSTACK is the stack state before the swap, and
793
   is updated to reflect the swap.  A swap insn is represented as a
794
   PARALLEL of two patterns: each pattern moves one reg to the other.
795
 
796
   If REG is already at the top of the stack, no insn is emitted.  */
797
 
798
static void
799
emit_swap_insn (rtx insn, stack regstack, rtx reg)
800
{
801
  int hard_regno;
802
  rtx swap_rtx;
803
  int tmp, other_reg;           /* swap regno temps */
804
  rtx i1;                       /* the stack-reg insn prior to INSN */
805
  rtx i1set = NULL_RTX;         /* the SET rtx within I1 */
806
 
807
  hard_regno = get_hard_regnum (regstack, reg);
808
 
809
  if (hard_regno == FIRST_STACK_REG)
810
    return;
811
  if (hard_regno == -1)
812
    {
813
      /* Something failed if the register wasn't on the stack.  If we had
814
         malformed asms, we zapped the instruction itself, but that didn't
815
         produce the same pattern of register sets as before.  To prevent
816
         further failure, adjust REGSTACK to include REG at TOP.  */
817
      gcc_assert (any_malformed_asm);
818
      regstack->reg[++regstack->top] = REGNO (reg);
819
      return;
820
    }
821
  gcc_assert (hard_regno >= FIRST_STACK_REG);
822
 
823
  other_reg = regstack->top - (hard_regno - FIRST_STACK_REG);
824
 
825
  tmp = regstack->reg[other_reg];
826
  regstack->reg[other_reg] = regstack->reg[regstack->top];
827
  regstack->reg[regstack->top] = tmp;
828
 
829
  /* Find the previous insn involving stack regs, but don't pass a
830
     block boundary.  */
831
  i1 = NULL;
832
  if (current_block && insn != BB_HEAD (current_block))
833
    {
834
      rtx tmp = PREV_INSN (insn);
835
      rtx limit = PREV_INSN (BB_HEAD (current_block));
836
      while (tmp != limit)
837
        {
838
          if (LABEL_P (tmp)
839
              || CALL_P (tmp)
840
              || NOTE_INSN_BASIC_BLOCK_P (tmp)
841
              || (NONJUMP_INSN_P (tmp)
842
                  && stack_regs_mentioned (tmp)))
843
            {
844
              i1 = tmp;
845
              break;
846
            }
847
          tmp = PREV_INSN (tmp);
848
        }
849
    }
850
 
851
  if (i1 != NULL_RTX
852
      && (i1set = single_set (i1)) != NULL_RTX)
853
    {
854
      rtx i1src = *get_true_reg (&SET_SRC (i1set));
855
      rtx i1dest = *get_true_reg (&SET_DEST (i1set));
856
 
857
      /* If the previous register stack push was from the reg we are to
858
         swap with, omit the swap.  */
859
 
860
      if (REG_P (i1dest) && REGNO (i1dest) == FIRST_STACK_REG
861
          && REG_P (i1src)
862
          && REGNO (i1src) == (unsigned) hard_regno - 1
863
          && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
864
        return;
865
 
866
      /* If the previous insn wrote to the reg we are to swap with,
867
         omit the swap.  */
868
 
869
      if (REG_P (i1dest) && REGNO (i1dest) == (unsigned) hard_regno
870
          && REG_P (i1src) && REGNO (i1src) == FIRST_STACK_REG
871
          && find_regno_note (i1, REG_DEAD, FIRST_STACK_REG) == NULL_RTX)
872
        return;
873
    }
874
 
875
  /* Avoid emitting the swap if this is the first register stack insn
876
     of the current_block.  Instead update the current_block's stack_in
877
     and let compensate edges take care of this for us.  */
878
  if (current_block && starting_stack_p)
879
    {
880
      BLOCK_INFO (current_block)->stack_in = *regstack;
881
      starting_stack_p = false;
882
      return;
883
    }
884
 
885
  swap_rtx = gen_swapxf (FP_MODE_REG (hard_regno, XFmode),
886
                         FP_MODE_REG (FIRST_STACK_REG, XFmode));
887
 
888
  if (i1)
889
    emit_insn_after (swap_rtx, i1);
890
  else if (current_block)
891
    emit_insn_before (swap_rtx, BB_HEAD (current_block));
892
  else
893
    emit_insn_before (swap_rtx, insn);
894
}
895
 
896
/* Emit an insns before INSN to swap virtual register SRC1 with
897
   the top of stack and virtual register SRC2 with second stack
898
   slot. REGSTACK is the stack state before the swaps, and
899
   is updated to reflect the swaps.  A swap insn is represented as a
900
   PARALLEL of two patterns: each pattern moves one reg to the other.
901
 
902
   If SRC1 and/or SRC2 are already at the right place, no swap insn
903
   is emitted.  */
904
 
905
static void
906
swap_to_top (rtx insn, stack regstack, rtx src1, rtx src2)
907
{
908
  struct stack_def temp_stack;
909
  int regno, j, k, temp;
910
 
911
  temp_stack = *regstack;
912
 
913
  /* Place operand 1 at the top of stack.  */
914
  regno = get_hard_regnum (&temp_stack, src1);
915
  gcc_assert (regno >= 0);
916
  if (regno != FIRST_STACK_REG)
917
    {
918
      k = temp_stack.top - (regno - FIRST_STACK_REG);
919
      j = temp_stack.top;
920
 
921
      temp = temp_stack.reg[k];
922
      temp_stack.reg[k] = temp_stack.reg[j];
923
      temp_stack.reg[j] = temp;
924
    }
925
 
926
  /* Place operand 2 next on the stack.  */
927
  regno = get_hard_regnum (&temp_stack, src2);
928
  gcc_assert (regno >= 0);
929
  if (regno != FIRST_STACK_REG + 1)
930
    {
931
      k = temp_stack.top - (regno - FIRST_STACK_REG);
932
      j = temp_stack.top - 1;
933
 
934
      temp = temp_stack.reg[k];
935
      temp_stack.reg[k] = temp_stack.reg[j];
936
      temp_stack.reg[j] = temp;
937
    }
938
 
939
  change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
940
}
941
 
942
/* Handle a move to or from a stack register in PAT, which is in INSN.
943
   REGSTACK is the current stack.  Return whether a control flow insn
944
   was deleted in the process.  */
945
 
946
static bool
947
move_for_stack_reg (rtx insn, stack regstack, rtx pat)
948
{
949
  rtx *psrc =  get_true_reg (&SET_SRC (pat));
950
  rtx *pdest = get_true_reg (&SET_DEST (pat));
951
  rtx src, dest;
952
  rtx note;
953
  bool control_flow_insn_deleted = false;
954
 
955
  src = *psrc; dest = *pdest;
956
 
957
  if (STACK_REG_P (src) && STACK_REG_P (dest))
958
    {
959
      /* Write from one stack reg to another.  If SRC dies here, then
960
         just change the register mapping and delete the insn.  */
961
 
962
      note = find_regno_note (insn, REG_DEAD, REGNO (src));
963
      if (note)
964
        {
965
          int i;
966
 
967
          /* If this is a no-op move, there must not be a REG_DEAD note.  */
968
          gcc_assert (REGNO (src) != REGNO (dest));
969
 
970
          for (i = regstack->top; i >= 0; i--)
971
            if (regstack->reg[i] == REGNO (src))
972
              break;
973
 
974
          /* The destination must be dead, or life analysis is borked.  */
975
          gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
976
 
977
          /* If the source is not live, this is yet another case of
978
             uninitialized variables.  Load up a NaN instead.  */
979
          if (i < 0)
980
            return move_nan_for_stack_reg (insn, regstack, dest);
981
 
982
          /* It is possible that the dest is unused after this insn.
983
             If so, just pop the src.  */
984
 
985
          if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
986
            emit_pop_insn (insn, regstack, src, EMIT_AFTER);
987
          else
988
            {
989
              regstack->reg[i] = REGNO (dest);
990
              SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
991
              CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
992
            }
993
 
994
          control_flow_insn_deleted |= control_flow_insn_p (insn);
995
          delete_insn (insn);
996
          return control_flow_insn_deleted;
997
        }
998
 
999
      /* The source reg does not die.  */
1000
 
1001
      /* If this appears to be a no-op move, delete it, or else it
1002
         will confuse the machine description output patterns. But if
1003
         it is REG_UNUSED, we must pop the reg now, as per-insn processing
1004
         for REG_UNUSED will not work for deleted insns.  */
1005
 
1006
      if (REGNO (src) == REGNO (dest))
1007
        {
1008
          if (find_regno_note (insn, REG_UNUSED, REGNO (dest)))
1009
            emit_pop_insn (insn, regstack, dest, EMIT_AFTER);
1010
 
1011
          control_flow_insn_deleted |= control_flow_insn_p (insn);
1012
          delete_insn (insn);
1013
          return control_flow_insn_deleted;
1014
        }
1015
 
1016
      /* The destination ought to be dead.  */
1017
      gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1018
 
1019
      replace_reg (psrc, get_hard_regnum (regstack, src));
1020
 
1021
      regstack->reg[++regstack->top] = REGNO (dest);
1022
      SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1023
      replace_reg (pdest, FIRST_STACK_REG);
1024
    }
1025
  else if (STACK_REG_P (src))
1026
    {
1027
      /* Save from a stack reg to MEM, or possibly integer reg.  Since
1028
         only top of stack may be saved, emit an exchange first if
1029
         needs be.  */
1030
 
1031
      emit_swap_insn (insn, regstack, src);
1032
 
1033
      note = find_regno_note (insn, REG_DEAD, REGNO (src));
1034
      if (note)
1035
        {
1036
          replace_reg (&XEXP (note, 0), FIRST_STACK_REG);
1037
          regstack->top--;
1038
          CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (src));
1039
        }
1040
      else if ((GET_MODE (src) == XFmode)
1041
               && regstack->top < REG_STACK_SIZE - 1)
1042
        {
1043
          /* A 387 cannot write an XFmode value to a MEM without
1044
             clobbering the source reg.  The output code can handle
1045
             this by reading back the value from the MEM.
1046
             But it is more efficient to use a temp register if one is
1047
             available.  Push the source value here if the register
1048
             stack is not full, and then write the value to memory via
1049
             a pop.  */
1050
          rtx push_rtx;
1051
          rtx top_stack_reg = FP_MODE_REG (FIRST_STACK_REG, GET_MODE (src));
1052
 
1053
          push_rtx = gen_movxf (top_stack_reg, top_stack_reg);
1054
          emit_insn_before (push_rtx, insn);
1055
          add_reg_note (insn, REG_DEAD, top_stack_reg);
1056
        }
1057
 
1058
      replace_reg (psrc, FIRST_STACK_REG);
1059
    }
1060
  else
1061
    {
1062
      rtx pat = PATTERN (insn);
1063
 
1064
      gcc_assert (STACK_REG_P (dest));
1065
 
1066
      /* Load from MEM, or possibly integer REG or constant, into the
1067
         stack regs.  The actual target is always the top of the
1068
         stack. The stack mapping is changed to reflect that DEST is
1069
         now at top of stack.  */
1070
 
1071
      /* The destination ought to be dead.  However, there is a
1072
         special case with i387 UNSPEC_TAN, where destination is live
1073
         (an argument to fptan) but inherent load of 1.0 is modelled
1074
         as a load from a constant.  */
1075
      if (GET_CODE (pat) == PARALLEL
1076
          && XVECLEN (pat, 0) == 2
1077
          && GET_CODE (XVECEXP (pat, 0, 1)) == SET
1078
          && GET_CODE (SET_SRC (XVECEXP (pat, 0, 1))) == UNSPEC
1079
          && XINT (SET_SRC (XVECEXP (pat, 0, 1)), 1) == UNSPEC_TAN)
1080
        emit_swap_insn (insn, regstack, dest);
1081
      else
1082
        gcc_assert (get_hard_regnum (regstack, dest) < FIRST_STACK_REG);
1083
 
1084
      gcc_assert (regstack->top < REG_STACK_SIZE);
1085
 
1086
      regstack->reg[++regstack->top] = REGNO (dest);
1087
      SET_HARD_REG_BIT (regstack->reg_set, REGNO (dest));
1088
      replace_reg (pdest, FIRST_STACK_REG);
1089
    }
1090
 
1091
  return control_flow_insn_deleted;
1092
}
1093
 
1094
/* A helper function which replaces INSN with a pattern that loads up
1095
   a NaN into DEST, then invokes move_for_stack_reg.  */
1096
 
1097
static bool
1098
move_nan_for_stack_reg (rtx insn, stack regstack, rtx dest)
1099
{
1100
  rtx pat;
1101
 
1102
  dest = FP_MODE_REG (REGNO (dest), SFmode);
1103
  pat = gen_rtx_SET (VOIDmode, dest, not_a_num);
1104
  PATTERN (insn) = pat;
1105
  INSN_CODE (insn) = -1;
1106
 
1107
  return move_for_stack_reg (insn, regstack, pat);
1108
}
1109
 
1110
/* Swap the condition on a branch, if there is one.  Return true if we
1111
   found a condition to swap.  False if the condition was not used as
1112
   such.  */
1113
 
1114
static int
1115
swap_rtx_condition_1 (rtx pat)
1116
{
1117
  const char *fmt;
1118
  int i, r = 0;
1119
 
1120
  if (COMPARISON_P (pat))
1121
    {
1122
      PUT_CODE (pat, swap_condition (GET_CODE (pat)));
1123
      r = 1;
1124
    }
1125
  else
1126
    {
1127
      fmt = GET_RTX_FORMAT (GET_CODE (pat));
1128
      for (i = GET_RTX_LENGTH (GET_CODE (pat)) - 1; i >= 0; i--)
1129
        {
1130
          if (fmt[i] == 'E')
1131
            {
1132
              int j;
1133
 
1134
              for (j = XVECLEN (pat, i) - 1; j >= 0; j--)
1135
                r |= swap_rtx_condition_1 (XVECEXP (pat, i, j));
1136
            }
1137
          else if (fmt[i] == 'e')
1138
            r |= swap_rtx_condition_1 (XEXP (pat, i));
1139
        }
1140
    }
1141
 
1142
  return r;
1143
}
1144
 
1145
static int
1146
swap_rtx_condition (rtx insn)
1147
{
1148
  rtx pat = PATTERN (insn);
1149
 
1150
  /* We're looking for a single set to cc0 or an HImode temporary.  */
1151
 
1152
  if (GET_CODE (pat) == SET
1153
      && REG_P (SET_DEST (pat))
1154
      && REGNO (SET_DEST (pat)) == FLAGS_REG)
1155
    {
1156
      insn = next_flags_user (insn);
1157
      if (insn == NULL_RTX)
1158
        return 0;
1159
      pat = PATTERN (insn);
1160
    }
1161
 
1162
  /* See if this is, or ends in, a fnstsw.  If so, we're not doing anything
1163
     with the cc value right now.  We may be able to search for one
1164
     though.  */
1165
 
1166
  if (GET_CODE (pat) == SET
1167
      && GET_CODE (SET_SRC (pat)) == UNSPEC
1168
      && XINT (SET_SRC (pat), 1) == UNSPEC_FNSTSW)
1169
    {
1170
      rtx dest = SET_DEST (pat);
1171
 
1172
      /* Search forward looking for the first use of this value.
1173
         Stop at block boundaries.  */
1174
      while (insn != BB_END (current_block))
1175
        {
1176
          insn = NEXT_INSN (insn);
1177
          if (INSN_P (insn) && reg_mentioned_p (dest, insn))
1178
            break;
1179
          if (CALL_P (insn))
1180
            return 0;
1181
        }
1182
 
1183
      /* We haven't found it.  */
1184
      if (insn == BB_END (current_block))
1185
        return 0;
1186
 
1187
      /* So we've found the insn using this value.  If it is anything
1188
         other than sahf or the value does not die (meaning we'd have
1189
         to search further), then we must give up.  */
1190
      pat = PATTERN (insn);
1191
      if (GET_CODE (pat) != SET
1192
          || GET_CODE (SET_SRC (pat)) != UNSPEC
1193
          || XINT (SET_SRC (pat), 1) != UNSPEC_SAHF
1194
          || ! dead_or_set_p (insn, dest))
1195
        return 0;
1196
 
1197
      /* Now we are prepared to handle this as a normal cc0 setter.  */
1198
      insn = next_flags_user (insn);
1199
      if (insn == NULL_RTX)
1200
        return 0;
1201
      pat = PATTERN (insn);
1202
    }
1203
 
1204
  if (swap_rtx_condition_1 (pat))
1205
    {
1206
      int fail = 0;
1207
      INSN_CODE (insn) = -1;
1208
      if (recog_memoized (insn) == -1)
1209
        fail = 1;
1210
      /* In case the flags don't die here, recurse to try fix
1211
         following user too.  */
1212
      else if (! dead_or_set_p (insn, ix86_flags_rtx))
1213
        {
1214
          insn = next_flags_user (insn);
1215
          if (!insn || !swap_rtx_condition (insn))
1216
            fail = 1;
1217
        }
1218
      if (fail)
1219
        {
1220
          swap_rtx_condition_1 (pat);
1221
          return 0;
1222
        }
1223
      return 1;
1224
    }
1225
  return 0;
1226
}
1227
 
1228
/* Handle a comparison.  Special care needs to be taken to avoid
1229
   causing comparisons that a 387 cannot do correctly, such as EQ.
1230
 
1231
   Also, a pop insn may need to be emitted.  The 387 does have an
1232
   `fcompp' insn that can pop two regs, but it is sometimes too expensive
1233
   to do this - a `fcomp' followed by a `fstpl %st(0)' may be easier to
1234
   set up.  */
1235
 
1236
static void
1237
compare_for_stack_reg (rtx insn, stack regstack, rtx pat_src)
1238
{
1239
  rtx *src1, *src2;
1240
  rtx src1_note, src2_note;
1241
 
1242
  src1 = get_true_reg (&XEXP (pat_src, 0));
1243
  src2 = get_true_reg (&XEXP (pat_src, 1));
1244
 
1245
  /* ??? If fxch turns out to be cheaper than fstp, give priority to
1246
     registers that die in this insn - move those to stack top first.  */
1247
  if ((! STACK_REG_P (*src1)
1248
       || (STACK_REG_P (*src2)
1249
           && get_hard_regnum (regstack, *src2) == FIRST_STACK_REG))
1250
      && swap_rtx_condition (insn))
1251
    {
1252
      rtx temp;
1253
      temp = XEXP (pat_src, 0);
1254
      XEXP (pat_src, 0) = XEXP (pat_src, 1);
1255
      XEXP (pat_src, 1) = temp;
1256
 
1257
      src1 = get_true_reg (&XEXP (pat_src, 0));
1258
      src2 = get_true_reg (&XEXP (pat_src, 1));
1259
 
1260
      INSN_CODE (insn) = -1;
1261
    }
1262
 
1263
  /* We will fix any death note later.  */
1264
 
1265
  src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1266
 
1267
  if (STACK_REG_P (*src2))
1268
    src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1269
  else
1270
    src2_note = NULL_RTX;
1271
 
1272
  emit_swap_insn (insn, regstack, *src1);
1273
 
1274
  replace_reg (src1, FIRST_STACK_REG);
1275
 
1276
  if (STACK_REG_P (*src2))
1277
    replace_reg (src2, get_hard_regnum (regstack, *src2));
1278
 
1279
  if (src1_note)
1280
    {
1281
      pop_stack (regstack, REGNO (XEXP (src1_note, 0)));
1282
      replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1283
    }
1284
 
1285
  /* If the second operand dies, handle that.  But if the operands are
1286
     the same stack register, don't bother, because only one death is
1287
     needed, and it was just handled.  */
1288
 
1289
  if (src2_note
1290
      && ! (STACK_REG_P (*src1) && STACK_REG_P (*src2)
1291
            && REGNO (*src1) == REGNO (*src2)))
1292
    {
1293
      /* As a special case, two regs may die in this insn if src2 is
1294
         next to top of stack and the top of stack also dies.  Since
1295
         we have already popped src1, "next to top of stack" is really
1296
         at top (FIRST_STACK_REG) now.  */
1297
 
1298
      if (get_hard_regnum (regstack, XEXP (src2_note, 0)) == FIRST_STACK_REG
1299
          && src1_note)
1300
        {
1301
          pop_stack (regstack, REGNO (XEXP (src2_note, 0)));
1302
          replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1303
        }
1304
      else
1305
        {
1306
          /* The 386 can only represent death of the first operand in
1307
             the case handled above.  In all other cases, emit a separate
1308
             pop and remove the death note from here.  */
1309
 
1310
          /* link_cc0_insns (insn); */
1311
 
1312
          remove_regno_note (insn, REG_DEAD, REGNO (XEXP (src2_note, 0)));
1313
 
1314
          emit_pop_insn (insn, regstack, XEXP (src2_note, 0),
1315
                         EMIT_AFTER);
1316
        }
1317
    }
1318
}
1319
 
1320
/* Substitute new registers in LOC, which is part of a debug insn.
1321
   REGSTACK is the current register layout.  */
1322
 
1323
static int
1324
subst_stack_regs_in_debug_insn (rtx *loc, void *data)
1325
{
1326
  rtx *tloc = get_true_reg (loc);
1327
  stack regstack = (stack)data;
1328
  int hard_regno;
1329
 
1330
  if (!STACK_REG_P (*tloc))
1331
    return 0;
1332
 
1333
  if (tloc != loc)
1334
    return 0;
1335
 
1336
  hard_regno = get_hard_regnum (regstack, *loc);
1337
  gcc_assert (hard_regno >= FIRST_STACK_REG);
1338
 
1339
  replace_reg (loc, hard_regno);
1340
 
1341
  return -1;
1342
}
1343
 
1344
/* Substitute new registers in PAT, which is part of INSN.  REGSTACK
1345
   is the current register layout.  Return whether a control flow insn
1346
   was deleted in the process.  */
1347
 
1348
static bool
1349
subst_stack_regs_pat (rtx insn, stack regstack, rtx pat)
1350
{
1351
  rtx *dest, *src;
1352
  bool control_flow_insn_deleted = false;
1353
 
1354
  switch (GET_CODE (pat))
1355
    {
1356
    case USE:
1357
      /* Deaths in USE insns can happen in non optimizing compilation.
1358
         Handle them by popping the dying register.  */
1359
      src = get_true_reg (&XEXP (pat, 0));
1360
      if (STACK_REG_P (*src)
1361
          && find_regno_note (insn, REG_DEAD, REGNO (*src)))
1362
        {
1363
          /* USEs are ignored for liveness information so USEs of dead
1364
             register might happen.  */
1365
          if (TEST_HARD_REG_BIT (regstack->reg_set, REGNO (*src)))
1366
            emit_pop_insn (insn, regstack, *src, EMIT_AFTER);
1367
          return control_flow_insn_deleted;
1368
        }
1369
      /* Uninitialized USE might happen for functions returning uninitialized
1370
         value.  We will properly initialize the USE on the edge to EXIT_BLOCK,
1371
         so it is safe to ignore the use here. This is consistent with behavior
1372
         of dataflow analyzer that ignores USE too.  (This also imply that
1373
         forcibly initializing the register to NaN here would lead to ICE later,
1374
         since the REG_DEAD notes are not issued.)  */
1375
      break;
1376
 
1377
    case VAR_LOCATION:
1378
      gcc_unreachable ();
1379
 
1380
    case CLOBBER:
1381
      {
1382
        rtx note;
1383
 
1384
        dest = get_true_reg (&XEXP (pat, 0));
1385
        if (STACK_REG_P (*dest))
1386
          {
1387
            note = find_reg_note (insn, REG_DEAD, *dest);
1388
 
1389
            if (pat != PATTERN (insn))
1390
              {
1391
                /* The fix_truncdi_1 pattern wants to be able to
1392
                   allocate its own scratch register.  It does this by
1393
                   clobbering an fp reg so that it is assured of an
1394
                   empty reg-stack register.  If the register is live,
1395
                   kill it now.  Remove the DEAD/UNUSED note so we
1396
                   don't try to kill it later too.
1397
 
1398
                   In reality the UNUSED note can be absent in some
1399
                   complicated cases when the register is reused for
1400
                   partially set variable.  */
1401
 
1402
                if (note)
1403
                  emit_pop_insn (insn, regstack, *dest, EMIT_BEFORE);
1404
                else
1405
                  note = find_reg_note (insn, REG_UNUSED, *dest);
1406
                if (note)
1407
                  remove_note (insn, note);
1408
                replace_reg (dest, FIRST_STACK_REG + 1);
1409
              }
1410
            else
1411
              {
1412
                /* A top-level clobber with no REG_DEAD, and no hard-regnum
1413
                   indicates an uninitialized value.  Because reload removed
1414
                   all other clobbers, this must be due to a function
1415
                   returning without a value.  Load up a NaN.  */
1416
 
1417
                if (!note)
1418
                  {
1419
                    rtx t = *dest;
1420
                    if (COMPLEX_MODE_P (GET_MODE (t)))
1421
                      {
1422
                        rtx u = FP_MODE_REG (REGNO (t) + 1, SFmode);
1423
                        if (get_hard_regnum (regstack, u) == -1)
1424
                          {
1425
                            rtx pat2 = gen_rtx_CLOBBER (VOIDmode, u);
1426
                            rtx insn2 = emit_insn_before (pat2, insn);
1427
                            control_flow_insn_deleted
1428
                              |= move_nan_for_stack_reg (insn2, regstack, u);
1429
                          }
1430
                      }
1431
                    if (get_hard_regnum (regstack, t) == -1)
1432
                      control_flow_insn_deleted
1433
                        |= move_nan_for_stack_reg (insn, regstack, t);
1434
                  }
1435
              }
1436
          }
1437
        break;
1438
      }
1439
 
1440
    case SET:
1441
      {
1442
        rtx *src1 = (rtx *) 0, *src2;
1443
        rtx src1_note, src2_note;
1444
        rtx pat_src;
1445
 
1446
        dest = get_true_reg (&SET_DEST (pat));
1447
        src  = get_true_reg (&SET_SRC (pat));
1448
        pat_src = SET_SRC (pat);
1449
 
1450
        /* See if this is a `movM' pattern, and handle elsewhere if so.  */
1451
        if (STACK_REG_P (*src)
1452
            || (STACK_REG_P (*dest)
1453
                && (REG_P (*src) || MEM_P (*src)
1454
                    || GET_CODE (*src) == CONST_DOUBLE)))
1455
          {
1456
            control_flow_insn_deleted |= move_for_stack_reg (insn, regstack, pat);
1457
            break;
1458
          }
1459
 
1460
        switch (GET_CODE (pat_src))
1461
          {
1462
          case COMPARE:
1463
            compare_for_stack_reg (insn, regstack, pat_src);
1464
            break;
1465
 
1466
          case CALL:
1467
            {
1468
              int count;
1469
              for (count = hard_regno_nregs[REGNO (*dest)][GET_MODE (*dest)];
1470
                   --count >= 0;)
1471
                {
1472
                  regstack->reg[++regstack->top] = REGNO (*dest) + count;
1473
                  SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest) + count);
1474
                }
1475
            }
1476
            replace_reg (dest, FIRST_STACK_REG);
1477
            break;
1478
 
1479
          case REG:
1480
            /* This is a `tstM2' case.  */
1481
            gcc_assert (*dest == cc0_rtx);
1482
            src1 = src;
1483
 
1484
            /* Fall through.  */
1485
 
1486
          case FLOAT_TRUNCATE:
1487
          case SQRT:
1488
          case ABS:
1489
          case NEG:
1490
            /* These insns only operate on the top of the stack. DEST might
1491
               be cc0_rtx if we're processing a tstM pattern. Also, it's
1492
               possible that the tstM case results in a REG_DEAD note on the
1493
               source.  */
1494
 
1495
            if (src1 == 0)
1496
              src1 = get_true_reg (&XEXP (pat_src, 0));
1497
 
1498
            emit_swap_insn (insn, regstack, *src1);
1499
 
1500
            src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1501
 
1502
            if (STACK_REG_P (*dest))
1503
              replace_reg (dest, FIRST_STACK_REG);
1504
 
1505
            if (src1_note)
1506
              {
1507
                replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1508
                regstack->top--;
1509
                CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1510
              }
1511
 
1512
            replace_reg (src1, FIRST_STACK_REG);
1513
            break;
1514
 
1515
          case MINUS:
1516
          case DIV:
1517
            /* On i386, reversed forms of subM3 and divM3 exist for
1518
               MODE_FLOAT, so the same code that works for addM3 and mulM3
1519
               can be used.  */
1520
          case MULT:
1521
          case PLUS:
1522
            /* These insns can accept the top of stack as a destination
1523
               from a stack reg or mem, or can use the top of stack as a
1524
               source and some other stack register (possibly top of stack)
1525
               as a destination.  */
1526
 
1527
            src1 = get_true_reg (&XEXP (pat_src, 0));
1528
            src2 = get_true_reg (&XEXP (pat_src, 1));
1529
 
1530
            /* We will fix any death note later.  */
1531
 
1532
            if (STACK_REG_P (*src1))
1533
              src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1534
            else
1535
              src1_note = NULL_RTX;
1536
            if (STACK_REG_P (*src2))
1537
              src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1538
            else
1539
              src2_note = NULL_RTX;
1540
 
1541
            /* If either operand is not a stack register, then the dest
1542
               must be top of stack.  */
1543
 
1544
            if (! STACK_REG_P (*src1) || ! STACK_REG_P (*src2))
1545
              emit_swap_insn (insn, regstack, *dest);
1546
            else
1547
              {
1548
                /* Both operands are REG.  If neither operand is already
1549
                   at the top of stack, choose to make the one that is the
1550
                   dest the new top of stack.  */
1551
 
1552
                int src1_hard_regnum, src2_hard_regnum;
1553
 
1554
                src1_hard_regnum = get_hard_regnum (regstack, *src1);
1555
                src2_hard_regnum = get_hard_regnum (regstack, *src2);
1556
 
1557
                /* If the source is not live, this is yet another case of
1558
                   uninitialized variables.  Load up a NaN instead.  */
1559
                if (src1_hard_regnum == -1)
1560
                  {
1561
                    rtx pat2 = gen_rtx_CLOBBER (VOIDmode, *src1);
1562
                    rtx insn2 = emit_insn_before (pat2, insn);
1563
                    control_flow_insn_deleted
1564
                      |= move_nan_for_stack_reg (insn2, regstack, *src1);
1565
                  }
1566
                if (src2_hard_regnum == -1)
1567
                  {
1568
                    rtx pat2 = gen_rtx_CLOBBER (VOIDmode, *src2);
1569
                    rtx insn2 = emit_insn_before (pat2, insn);
1570
                    control_flow_insn_deleted
1571
                      |= move_nan_for_stack_reg (insn2, regstack, *src2);
1572
                  }
1573
 
1574
                if (src1_hard_regnum != FIRST_STACK_REG
1575
                    && src2_hard_regnum != FIRST_STACK_REG)
1576
                  emit_swap_insn (insn, regstack, *dest);
1577
              }
1578
 
1579
            if (STACK_REG_P (*src1))
1580
              replace_reg (src1, get_hard_regnum (regstack, *src1));
1581
            if (STACK_REG_P (*src2))
1582
              replace_reg (src2, get_hard_regnum (regstack, *src2));
1583
 
1584
            if (src1_note)
1585
              {
1586
                rtx src1_reg = XEXP (src1_note, 0);
1587
 
1588
                /* If the register that dies is at the top of stack, then
1589
                   the destination is somewhere else - merely substitute it.
1590
                   But if the reg that dies is not at top of stack, then
1591
                   move the top of stack to the dead reg, as though we had
1592
                   done the insn and then a store-with-pop.  */
1593
 
1594
                if (REGNO (src1_reg) == regstack->reg[regstack->top])
1595
                  {
1596
                    SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1597
                    replace_reg (dest, get_hard_regnum (regstack, *dest));
1598
                  }
1599
                else
1600
                  {
1601
                    int regno = get_hard_regnum (regstack, src1_reg);
1602
 
1603
                    SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1604
                    replace_reg (dest, regno);
1605
 
1606
                    regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1607
                      = regstack->reg[regstack->top];
1608
                  }
1609
 
1610
                CLEAR_HARD_REG_BIT (regstack->reg_set,
1611
                                    REGNO (XEXP (src1_note, 0)));
1612
                replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1613
                regstack->top--;
1614
              }
1615
            else if (src2_note)
1616
              {
1617
                rtx src2_reg = XEXP (src2_note, 0);
1618
                if (REGNO (src2_reg) == regstack->reg[regstack->top])
1619
                  {
1620
                    SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1621
                    replace_reg (dest, get_hard_regnum (regstack, *dest));
1622
                  }
1623
                else
1624
                  {
1625
                    int regno = get_hard_regnum (regstack, src2_reg);
1626
 
1627
                    SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1628
                    replace_reg (dest, regno);
1629
 
1630
                    regstack->reg[regstack->top - (regno - FIRST_STACK_REG)]
1631
                      = regstack->reg[regstack->top];
1632
                  }
1633
 
1634
                CLEAR_HARD_REG_BIT (regstack->reg_set,
1635
                                    REGNO (XEXP (src2_note, 0)));
1636
                replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG);
1637
                regstack->top--;
1638
              }
1639
            else
1640
              {
1641
                SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1642
                replace_reg (dest, get_hard_regnum (regstack, *dest));
1643
              }
1644
 
1645
            /* Keep operand 1 matching with destination.  */
1646
            if (COMMUTATIVE_ARITH_P (pat_src)
1647
                && REG_P (*src1) && REG_P (*src2)
1648
                && REGNO (*src1) != REGNO (*dest))
1649
             {
1650
                int tmp = REGNO (*src1);
1651
                replace_reg (src1, REGNO (*src2));
1652
                replace_reg (src2, tmp);
1653
             }
1654
            break;
1655
 
1656
          case UNSPEC:
1657
            switch (XINT (pat_src, 1))
1658
              {
1659
              case UNSPEC_FIST:
1660
 
1661
              case UNSPEC_FIST_FLOOR:
1662
              case UNSPEC_FIST_CEIL:
1663
 
1664
                /* These insns only operate on the top of the stack.  */
1665
 
1666
                src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1667
                emit_swap_insn (insn, regstack, *src1);
1668
 
1669
                src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1670
 
1671
                if (STACK_REG_P (*dest))
1672
                  replace_reg (dest, FIRST_STACK_REG);
1673
 
1674
                if (src1_note)
1675
                  {
1676
                    replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1677
                    regstack->top--;
1678
                    CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (*src1));
1679
                  }
1680
 
1681
                replace_reg (src1, FIRST_STACK_REG);
1682
                break;
1683
 
1684
              case UNSPEC_FXAM:
1685
 
1686
                /* This insn only operate on the top of the stack.  */
1687
 
1688
                src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1689
                emit_swap_insn (insn, regstack, *src1);
1690
 
1691
                src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1692
 
1693
                replace_reg (src1, FIRST_STACK_REG);
1694
 
1695
                if (src1_note)
1696
                  {
1697
                    remove_regno_note (insn, REG_DEAD,
1698
                                       REGNO (XEXP (src1_note, 0)));
1699
                    emit_pop_insn (insn, regstack, XEXP (src1_note, 0),
1700
                                   EMIT_AFTER);
1701
                  }
1702
 
1703
                break;
1704
 
1705
              case UNSPEC_SIN:
1706
              case UNSPEC_COS:
1707
              case UNSPEC_FRNDINT:
1708
              case UNSPEC_F2XM1:
1709
 
1710
              case UNSPEC_FRNDINT_FLOOR:
1711
              case UNSPEC_FRNDINT_CEIL:
1712
              case UNSPEC_FRNDINT_TRUNC:
1713
              case UNSPEC_FRNDINT_MASK_PM:
1714
 
1715
                /* Above insns operate on the top of the stack.  */
1716
 
1717
              case UNSPEC_SINCOS_COS:
1718
              case UNSPEC_XTRACT_FRACT:
1719
 
1720
                /* Above insns operate on the top two stack slots,
1721
                   first part of one input, double output insn.  */
1722
 
1723
                src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1724
 
1725
                emit_swap_insn (insn, regstack, *src1);
1726
 
1727
                /* Input should never die, it is replaced with output.  */
1728
                src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1729
                gcc_assert (!src1_note);
1730
 
1731
                if (STACK_REG_P (*dest))
1732
                  replace_reg (dest, FIRST_STACK_REG);
1733
 
1734
                replace_reg (src1, FIRST_STACK_REG);
1735
                break;
1736
 
1737
              case UNSPEC_SINCOS_SIN:
1738
              case UNSPEC_XTRACT_EXP:
1739
 
1740
                /* These insns operate on the top two stack slots,
1741
                   second part of one input, double output insn.  */
1742
 
1743
                regstack->top++;
1744
                /* FALLTHRU */
1745
 
1746
              case UNSPEC_TAN:
1747
 
1748
                /* For UNSPEC_TAN, regstack->top is already increased
1749
                   by inherent load of constant 1.0.  */
1750
 
1751
                /* Output value is generated in the second stack slot.
1752
                   Move current value from second slot to the top.  */
1753
                regstack->reg[regstack->top]
1754
                  = regstack->reg[regstack->top - 1];
1755
 
1756
                gcc_assert (STACK_REG_P (*dest));
1757
 
1758
                regstack->reg[regstack->top - 1] = REGNO (*dest);
1759
                SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1760
                replace_reg (dest, FIRST_STACK_REG + 1);
1761
 
1762
                src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1763
 
1764
                replace_reg (src1, FIRST_STACK_REG);
1765
                break;
1766
 
1767
              case UNSPEC_FPATAN:
1768
              case UNSPEC_FYL2X:
1769
              case UNSPEC_FYL2XP1:
1770
                /* These insns operate on the top two stack slots.  */
1771
 
1772
                src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1773
                src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1774
 
1775
                src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1776
                src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1777
 
1778
                swap_to_top (insn, regstack, *src1, *src2);
1779
 
1780
                replace_reg (src1, FIRST_STACK_REG);
1781
                replace_reg (src2, FIRST_STACK_REG + 1);
1782
 
1783
                if (src1_note)
1784
                  replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
1785
                if (src2_note)
1786
                  replace_reg (&XEXP (src2_note, 0), FIRST_STACK_REG + 1);
1787
 
1788
                /* Pop both input operands from the stack.  */
1789
                CLEAR_HARD_REG_BIT (regstack->reg_set,
1790
                                    regstack->reg[regstack->top]);
1791
                CLEAR_HARD_REG_BIT (regstack->reg_set,
1792
                                    regstack->reg[regstack->top - 1]);
1793
                regstack->top -= 2;
1794
 
1795
                /* Push the result back onto the stack.  */
1796
                regstack->reg[++regstack->top] = REGNO (*dest);
1797
                SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1798
                replace_reg (dest, FIRST_STACK_REG);
1799
                break;
1800
 
1801
              case UNSPEC_FSCALE_FRACT:
1802
              case UNSPEC_FPREM_F:
1803
              case UNSPEC_FPREM1_F:
1804
                /* These insns operate on the top two stack slots,
1805
                   first part of double input, double output insn.  */
1806
 
1807
                src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1808
                src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1809
 
1810
                src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1811
                src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1812
 
1813
                /* Inputs should never die, they are
1814
                   replaced with outputs.  */
1815
                gcc_assert (!src1_note);
1816
                gcc_assert (!src2_note);
1817
 
1818
                swap_to_top (insn, regstack, *src1, *src2);
1819
 
1820
                /* Push the result back onto stack. Empty stack slot
1821
                   will be filled in second part of insn.  */
1822
                if (STACK_REG_P (*dest))
1823
                  {
1824
                    regstack->reg[regstack->top] = REGNO (*dest);
1825
                    SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1826
                    replace_reg (dest, FIRST_STACK_REG);
1827
                  }
1828
 
1829
                replace_reg (src1, FIRST_STACK_REG);
1830
                replace_reg (src2, FIRST_STACK_REG + 1);
1831
                break;
1832
 
1833
              case UNSPEC_FSCALE_EXP:
1834
              case UNSPEC_FPREM_U:
1835
              case UNSPEC_FPREM1_U:
1836
                /* These insns operate on the top two stack slots,
1837
                   second part of double input, double output insn.  */
1838
 
1839
                src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1840
                src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1841
 
1842
                /* Push the result back onto stack. Fill empty slot from
1843
                   first part of insn and fix top of stack pointer.  */
1844
                if (STACK_REG_P (*dest))
1845
                  {
1846
                    regstack->reg[regstack->top - 1] = REGNO (*dest);
1847
                    SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1848
                    replace_reg (dest, FIRST_STACK_REG + 1);
1849
                  }
1850
 
1851
                replace_reg (src1, FIRST_STACK_REG);
1852
                replace_reg (src2, FIRST_STACK_REG + 1);
1853
                break;
1854
 
1855
              case UNSPEC_C2_FLAG:
1856
                /* This insn operates on the top two stack slots,
1857
                   third part of C2 setting double input insn.  */
1858
 
1859
                src1 = get_true_reg (&XVECEXP (pat_src, 0, 0));
1860
                src2 = get_true_reg (&XVECEXP (pat_src, 0, 1));
1861
 
1862
                replace_reg (src1, FIRST_STACK_REG);
1863
                replace_reg (src2, FIRST_STACK_REG + 1);
1864
                break;
1865
 
1866
              case UNSPEC_SAHF:
1867
                /* (unspec [(unspec [(compare)] UNSPEC_FNSTSW)] UNSPEC_SAHF)
1868
                   The combination matches the PPRO fcomi instruction.  */
1869
 
1870
                pat_src = XVECEXP (pat_src, 0, 0);
1871
                gcc_assert (GET_CODE (pat_src) == UNSPEC);
1872
                gcc_assert (XINT (pat_src, 1) == UNSPEC_FNSTSW);
1873
                /* Fall through.  */
1874
 
1875
              case UNSPEC_FNSTSW:
1876
                /* Combined fcomp+fnstsw generated for doing well with
1877
                   CSE.  When optimizing this would have been broken
1878
                   up before now.  */
1879
 
1880
                pat_src = XVECEXP (pat_src, 0, 0);
1881
                gcc_assert (GET_CODE (pat_src) == COMPARE);
1882
 
1883
                compare_for_stack_reg (insn, regstack, pat_src);
1884
                break;
1885
 
1886
              default:
1887
                gcc_unreachable ();
1888
              }
1889
            break;
1890
 
1891
          case IF_THEN_ELSE:
1892
            /* This insn requires the top of stack to be the destination.  */
1893
 
1894
            src1 = get_true_reg (&XEXP (pat_src, 1));
1895
            src2 = get_true_reg (&XEXP (pat_src, 2));
1896
 
1897
            src1_note = find_regno_note (insn, REG_DEAD, REGNO (*src1));
1898
            src2_note = find_regno_note (insn, REG_DEAD, REGNO (*src2));
1899
 
1900
            /* If the comparison operator is an FP comparison operator,
1901
               it is handled correctly by compare_for_stack_reg () who
1902
               will move the destination to the top of stack. But if the
1903
               comparison operator is not an FP comparison operator, we
1904
               have to handle it here.  */
1905
            if (get_hard_regnum (regstack, *dest) >= FIRST_STACK_REG
1906
                && REGNO (*dest) != regstack->reg[regstack->top])
1907
              {
1908
                /* In case one of operands is the top of stack and the operands
1909
                   dies, it is safe to make it the destination operand by
1910
                   reversing the direction of cmove and avoid fxch.  */
1911
                if ((REGNO (*src1) == regstack->reg[regstack->top]
1912
                     && src1_note)
1913
                    || (REGNO (*src2) == regstack->reg[regstack->top]
1914
                        && src2_note))
1915
                  {
1916
                    int idx1 = (get_hard_regnum (regstack, *src1)
1917
                                - FIRST_STACK_REG);
1918
                    int idx2 = (get_hard_regnum (regstack, *src2)
1919
                                - FIRST_STACK_REG);
1920
 
1921
                    /* Make reg-stack believe that the operands are already
1922
                       swapped on the stack */
1923
                    regstack->reg[regstack->top - idx1] = REGNO (*src2);
1924
                    regstack->reg[regstack->top - idx2] = REGNO (*src1);
1925
 
1926
                    /* Reverse condition to compensate the operand swap.
1927
                       i386 do have comparison always reversible.  */
1928
                    PUT_CODE (XEXP (pat_src, 0),
1929
                              reversed_comparison_code (XEXP (pat_src, 0), insn));
1930
                  }
1931
                else
1932
                  emit_swap_insn (insn, regstack, *dest);
1933
              }
1934
 
1935
            {
1936
              rtx src_note [3];
1937
              int i;
1938
 
1939
              src_note[0] = 0;
1940
              src_note[1] = src1_note;
1941
              src_note[2] = src2_note;
1942
 
1943
              if (STACK_REG_P (*src1))
1944
                replace_reg (src1, get_hard_regnum (regstack, *src1));
1945
              if (STACK_REG_P (*src2))
1946
                replace_reg (src2, get_hard_regnum (regstack, *src2));
1947
 
1948
              for (i = 1; i <= 2; i++)
1949
                if (src_note [i])
1950
                  {
1951
                    int regno = REGNO (XEXP (src_note[i], 0));
1952
 
1953
                    /* If the register that dies is not at the top of
1954
                       stack, then move the top of stack to the dead reg.
1955
                       Top of stack should never die, as it is the
1956
                       destination.  */
1957
                    gcc_assert (regno != regstack->reg[regstack->top]);
1958
                    remove_regno_note (insn, REG_DEAD, regno);
1959
                    emit_pop_insn (insn, regstack, XEXP (src_note[i], 0),
1960
                                    EMIT_AFTER);
1961
                  }
1962
            }
1963
 
1964
            /* Make dest the top of stack.  Add dest to regstack if
1965
               not present.  */
1966
            if (get_hard_regnum (regstack, *dest) < FIRST_STACK_REG)
1967
              regstack->reg[++regstack->top] = REGNO (*dest);
1968
            SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
1969
            replace_reg (dest, FIRST_STACK_REG);
1970
            break;
1971
 
1972
          default:
1973
            gcc_unreachable ();
1974
          }
1975
        break;
1976
      }
1977
 
1978
    default:
1979
      break;
1980
    }
1981
 
1982
  return control_flow_insn_deleted;
1983
}
1984
 
1985
/* Substitute hard regnums for any stack regs in INSN, which has
1986
   N_INPUTS inputs and N_OUTPUTS outputs.  REGSTACK is the stack info
1987
   before the insn, and is updated with changes made here.
1988
 
1989
   There are several requirements and assumptions about the use of
1990
   stack-like regs in asm statements.  These rules are enforced by
1991
   record_asm_stack_regs; see comments there for details.  Any
1992
   asm_operands left in the RTL at this point may be assume to meet the
1993
   requirements, since record_asm_stack_regs removes any problem asm.  */
1994
 
1995
static void
1996
subst_asm_stack_regs (rtx insn, stack regstack)
1997
{
1998
  rtx body = PATTERN (insn);
1999
  int alt;
2000
 
2001
  rtx *note_reg;                /* Array of note contents */
2002
  rtx **note_loc;               /* Address of REG field of each note */
2003
  enum reg_note *note_kind;     /* The type of each note */
2004
 
2005
  rtx *clobber_reg = 0;
2006
  rtx **clobber_loc = 0;
2007
 
2008
  struct stack_def temp_stack;
2009
  int n_notes;
2010
  int n_clobbers;
2011
  rtx note;
2012
  int i;
2013
  int n_inputs, n_outputs;
2014
 
2015
  if (! check_asm_stack_operands (insn))
2016
    return;
2017
 
2018
  /* Find out what the constraints required.  If no constraint
2019
     alternative matches, that is a compiler bug: we should have caught
2020
     such an insn in check_asm_stack_operands.  */
2021
  extract_insn (insn);
2022
  constrain_operands (1);
2023
  alt = which_alternative;
2024
 
2025
  preprocess_constraints ();
2026
 
2027
  get_asm_operands_in_out (body, &n_outputs, &n_inputs);
2028
 
2029
  gcc_assert (alt >= 0);
2030
 
2031
  /* Strip SUBREGs here to make the following code simpler.  */
2032
  for (i = 0; i < recog_data.n_operands; i++)
2033
    if (GET_CODE (recog_data.operand[i]) == SUBREG
2034
        && REG_P (SUBREG_REG (recog_data.operand[i])))
2035
      {
2036
        recog_data.operand_loc[i] = & SUBREG_REG (recog_data.operand[i]);
2037
        recog_data.operand[i] = SUBREG_REG (recog_data.operand[i]);
2038
      }
2039
 
2040
  /* Set up NOTE_REG, NOTE_LOC and NOTE_KIND.  */
2041
 
2042
  for (i = 0, note = REG_NOTES (insn); note; note = XEXP (note, 1))
2043
    i++;
2044
 
2045
  note_reg = XALLOCAVEC (rtx, i);
2046
  note_loc = XALLOCAVEC (rtx *, i);
2047
  note_kind = XALLOCAVEC (enum reg_note, i);
2048
 
2049
  n_notes = 0;
2050
  for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2051
    {
2052
      rtx reg = XEXP (note, 0);
2053
      rtx *loc = & XEXP (note, 0);
2054
 
2055
      if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
2056
        {
2057
          loc = & SUBREG_REG (reg);
2058
          reg = SUBREG_REG (reg);
2059
        }
2060
 
2061
      if (STACK_REG_P (reg)
2062
          && (REG_NOTE_KIND (note) == REG_DEAD
2063
              || REG_NOTE_KIND (note) == REG_UNUSED))
2064
        {
2065
          note_reg[n_notes] = reg;
2066
          note_loc[n_notes] = loc;
2067
          note_kind[n_notes] = REG_NOTE_KIND (note);
2068
          n_notes++;
2069
        }
2070
    }
2071
 
2072
  /* Set up CLOBBER_REG and CLOBBER_LOC.  */
2073
 
2074
  n_clobbers = 0;
2075
 
2076
  if (GET_CODE (body) == PARALLEL)
2077
    {
2078
      clobber_reg = XALLOCAVEC (rtx, XVECLEN (body, 0));
2079
      clobber_loc = XALLOCAVEC (rtx *, XVECLEN (body, 0));
2080
 
2081
      for (i = 0; i < XVECLEN (body, 0); i++)
2082
        if (GET_CODE (XVECEXP (body, 0, i)) == CLOBBER)
2083
          {
2084
            rtx clobber = XVECEXP (body, 0, i);
2085
            rtx reg = XEXP (clobber, 0);
2086
            rtx *loc = & XEXP (clobber, 0);
2087
 
2088
            if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg)))
2089
              {
2090
                loc = & SUBREG_REG (reg);
2091
                reg = SUBREG_REG (reg);
2092
              }
2093
 
2094
            if (STACK_REG_P (reg))
2095
              {
2096
                clobber_reg[n_clobbers] = reg;
2097
                clobber_loc[n_clobbers] = loc;
2098
                n_clobbers++;
2099
              }
2100
          }
2101
    }
2102
 
2103
  temp_stack = *regstack;
2104
 
2105
  /* Put the input regs into the desired place in TEMP_STACK.  */
2106
 
2107
  for (i = n_outputs; i < n_outputs + n_inputs; i++)
2108
    if (STACK_REG_P (recog_data.operand[i])
2109
        && reg_class_subset_p (recog_op_alt[i][alt].cl,
2110
                               FLOAT_REGS)
2111
        && recog_op_alt[i][alt].cl != FLOAT_REGS)
2112
      {
2113
        /* If an operand needs to be in a particular reg in
2114
           FLOAT_REGS, the constraint was either 't' or 'u'.  Since
2115
           these constraints are for single register classes, and
2116
           reload guaranteed that operand[i] is already in that class,
2117
           we can just use REGNO (recog_data.operand[i]) to know which
2118
           actual reg this operand needs to be in.  */
2119
 
2120
        int regno = get_hard_regnum (&temp_stack, recog_data.operand[i]);
2121
 
2122
        gcc_assert (regno >= 0);
2123
 
2124
        if ((unsigned int) regno != REGNO (recog_data.operand[i]))
2125
          {
2126
            /* recog_data.operand[i] is not in the right place.  Find
2127
               it and swap it with whatever is already in I's place.
2128
               K is where recog_data.operand[i] is now.  J is where it
2129
               should be.  */
2130
            int j, k, temp;
2131
 
2132
            k = temp_stack.top - (regno - FIRST_STACK_REG);
2133
            j = (temp_stack.top
2134
                 - (REGNO (recog_data.operand[i]) - FIRST_STACK_REG));
2135
 
2136
            temp = temp_stack.reg[k];
2137
            temp_stack.reg[k] = temp_stack.reg[j];
2138
            temp_stack.reg[j] = temp;
2139
          }
2140
      }
2141
 
2142
  /* Emit insns before INSN to make sure the reg-stack is in the right
2143
     order.  */
2144
 
2145
  change_stack (insn, regstack, &temp_stack, EMIT_BEFORE);
2146
 
2147
  /* Make the needed input register substitutions.  Do death notes and
2148
     clobbers too, because these are for inputs, not outputs.  */
2149
 
2150
  for (i = n_outputs; i < n_outputs + n_inputs; i++)
2151
    if (STACK_REG_P (recog_data.operand[i]))
2152
      {
2153
        int regnum = get_hard_regnum (regstack, recog_data.operand[i]);
2154
 
2155
        gcc_assert (regnum >= 0);
2156
 
2157
        replace_reg (recog_data.operand_loc[i], regnum);
2158
      }
2159
 
2160
  for (i = 0; i < n_notes; i++)
2161
    if (note_kind[i] == REG_DEAD)
2162
      {
2163
        int regnum = get_hard_regnum (regstack, note_reg[i]);
2164
 
2165
        gcc_assert (regnum >= 0);
2166
 
2167
        replace_reg (note_loc[i], regnum);
2168
      }
2169
 
2170
  for (i = 0; i < n_clobbers; i++)
2171
    {
2172
      /* It's OK for a CLOBBER to reference a reg that is not live.
2173
         Don't try to replace it in that case.  */
2174
      int regnum = get_hard_regnum (regstack, clobber_reg[i]);
2175
 
2176
      if (regnum >= 0)
2177
        {
2178
          /* Sigh - clobbers always have QImode.  But replace_reg knows
2179
             that these regs can't be MODE_INT and will assert.  Just put
2180
             the right reg there without calling replace_reg.  */
2181
 
2182
          *clobber_loc[i] = FP_MODE_REG (regnum, DFmode);
2183
        }
2184
    }
2185
 
2186
  /* Now remove from REGSTACK any inputs that the asm implicitly popped.  */
2187
 
2188
  for (i = n_outputs; i < n_outputs + n_inputs; i++)
2189
    if (STACK_REG_P (recog_data.operand[i]))
2190
      {
2191
        /* An input reg is implicitly popped if it is tied to an
2192
           output, or if there is a CLOBBER for it.  */
2193
        int j;
2194
 
2195
        for (j = 0; j < n_clobbers; j++)
2196
          if (operands_match_p (clobber_reg[j], recog_data.operand[i]))
2197
            break;
2198
 
2199
        if (j < n_clobbers || recog_op_alt[i][alt].matches >= 0)
2200
          {
2201
            /* recog_data.operand[i] might not be at the top of stack.
2202
               But that's OK, because all we need to do is pop the
2203
               right number of regs off of the top of the reg-stack.
2204
               record_asm_stack_regs guaranteed that all implicitly
2205
               popped regs were grouped at the top of the reg-stack.  */
2206
 
2207
            CLEAR_HARD_REG_BIT (regstack->reg_set,
2208
                                regstack->reg[regstack->top]);
2209
            regstack->top--;
2210
          }
2211
      }
2212
 
2213
  /* Now add to REGSTACK any outputs that the asm implicitly pushed.
2214
     Note that there isn't any need to substitute register numbers.
2215
     ???  Explain why this is true.  */
2216
 
2217
  for (i = LAST_STACK_REG; i >= FIRST_STACK_REG; i--)
2218
    {
2219
      /* See if there is an output for this hard reg.  */
2220
      int j;
2221
 
2222
      for (j = 0; j < n_outputs; j++)
2223
        if (STACK_REG_P (recog_data.operand[j])
2224
            && REGNO (recog_data.operand[j]) == (unsigned) i)
2225
          {
2226
            regstack->reg[++regstack->top] = i;
2227
            SET_HARD_REG_BIT (regstack->reg_set, i);
2228
            break;
2229
          }
2230
    }
2231
 
2232
  /* Now emit a pop insn for any REG_UNUSED output, or any REG_DEAD
2233
     input that the asm didn't implicitly pop.  If the asm didn't
2234
     implicitly pop an input reg, that reg will still be live.
2235
 
2236
     Note that we can't use find_regno_note here: the register numbers
2237
     in the death notes have already been substituted.  */
2238
 
2239
  for (i = 0; i < n_outputs; i++)
2240
    if (STACK_REG_P (recog_data.operand[i]))
2241
      {
2242
        int j;
2243
 
2244
        for (j = 0; j < n_notes; j++)
2245
          if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2246
              && note_kind[j] == REG_UNUSED)
2247
            {
2248
              insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2249
                                    EMIT_AFTER);
2250
              break;
2251
            }
2252
      }
2253
 
2254
  for (i = n_outputs; i < n_outputs + n_inputs; i++)
2255
    if (STACK_REG_P (recog_data.operand[i]))
2256
      {
2257
        int j;
2258
 
2259
        for (j = 0; j < n_notes; j++)
2260
          if (REGNO (recog_data.operand[i]) == REGNO (note_reg[j])
2261
              && note_kind[j] == REG_DEAD
2262
              && TEST_HARD_REG_BIT (regstack->reg_set,
2263
                                    REGNO (recog_data.operand[i])))
2264
            {
2265
              insn = emit_pop_insn (insn, regstack, recog_data.operand[i],
2266
                                    EMIT_AFTER);
2267
              break;
2268
            }
2269
      }
2270
}
2271
 
2272
/* Substitute stack hard reg numbers for stack virtual registers in
2273
   INSN.  Non-stack register numbers are not changed.  REGSTACK is the
2274
   current stack content.  Insns may be emitted as needed to arrange the
2275
   stack for the 387 based on the contents of the insn.  Return whether
2276
   a control flow insn was deleted in the process.  */
2277
 
2278
static bool
2279
subst_stack_regs (rtx insn, stack regstack)
2280
{
2281
  rtx *note_link, note;
2282
  bool control_flow_insn_deleted = false;
2283
  int i;
2284
 
2285
  if (CALL_P (insn))
2286
    {
2287
      int top = regstack->top;
2288
 
2289
      /* If there are any floating point parameters to be passed in
2290
         registers for this call, make sure they are in the right
2291
         order.  */
2292
 
2293
      if (top >= 0)
2294
        {
2295
          straighten_stack (insn, regstack);
2296
 
2297
          /* Now mark the arguments as dead after the call.  */
2298
 
2299
          while (regstack->top >= 0)
2300
            {
2301
              CLEAR_HARD_REG_BIT (regstack->reg_set, FIRST_STACK_REG + regstack->top);
2302
              regstack->top--;
2303
            }
2304
        }
2305
    }
2306
 
2307
  /* Do the actual substitution if any stack regs are mentioned.
2308
     Since we only record whether entire insn mentions stack regs, and
2309
     subst_stack_regs_pat only works for patterns that contain stack regs,
2310
     we must check each pattern in a parallel here.  A call_value_pop could
2311
     fail otherwise.  */
2312
 
2313
  if (stack_regs_mentioned (insn))
2314
    {
2315
      int n_operands = asm_noperands (PATTERN (insn));
2316
      if (n_operands >= 0)
2317
        {
2318
          /* This insn is an `asm' with operands.  Decode the operands,
2319
             decide how many are inputs, and do register substitution.
2320
             Any REG_UNUSED notes will be handled by subst_asm_stack_regs.  */
2321
 
2322
          subst_asm_stack_regs (insn, regstack);
2323
          return control_flow_insn_deleted;
2324
        }
2325
 
2326
      if (GET_CODE (PATTERN (insn)) == PARALLEL)
2327
        for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
2328
          {
2329
            if (stack_regs_mentioned_p (XVECEXP (PATTERN (insn), 0, i)))
2330
              {
2331
                if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == CLOBBER)
2332
                   XVECEXP (PATTERN (insn), 0, i)
2333
                     = shallow_copy_rtx (XVECEXP (PATTERN (insn), 0, i));
2334
                control_flow_insn_deleted
2335
                  |= subst_stack_regs_pat (insn, regstack,
2336
                                           XVECEXP (PATTERN (insn), 0, i));
2337
              }
2338
          }
2339
      else
2340
        control_flow_insn_deleted
2341
          |= subst_stack_regs_pat (insn, regstack, PATTERN (insn));
2342
    }
2343
 
2344
  /* subst_stack_regs_pat may have deleted a no-op insn.  If so, any
2345
     REG_UNUSED will already have been dealt with, so just return.  */
2346
 
2347
  if (NOTE_P (insn) || INSN_DELETED_P (insn))
2348
    return control_flow_insn_deleted;
2349
 
2350
  /* If this a noreturn call, we can't insert pop insns after it.
2351
     Instead, reset the stack state to empty.  */
2352
  if (CALL_P (insn)
2353
      && find_reg_note (insn, REG_NORETURN, NULL))
2354
    {
2355
      regstack->top = -1;
2356
      CLEAR_HARD_REG_SET (regstack->reg_set);
2357
      return control_flow_insn_deleted;
2358
    }
2359
 
2360
  /* If there is a REG_UNUSED note on a stack register on this insn,
2361
     the indicated reg must be popped.  The REG_UNUSED note is removed,
2362
     since the form of the newly emitted pop insn references the reg,
2363
     making it no longer `unset'.  */
2364
 
2365
  note_link = &REG_NOTES (insn);
2366
  for (note = *note_link; note; note = XEXP (note, 1))
2367
    if (REG_NOTE_KIND (note) == REG_UNUSED && STACK_REG_P (XEXP (note, 0)))
2368
      {
2369
        *note_link = XEXP (note, 1);
2370
        insn = emit_pop_insn (insn, regstack, XEXP (note, 0), EMIT_AFTER);
2371
      }
2372
    else
2373
      note_link = &XEXP (note, 1);
2374
 
2375
  return control_flow_insn_deleted;
2376
}
2377
 
2378
/* Change the organization of the stack so that it fits a new basic
2379
   block.  Some registers might have to be popped, but there can never be
2380
   a register live in the new block that is not now live.
2381
 
2382
   Insert any needed insns before or after INSN, as indicated by
2383
   WHERE.  OLD is the original stack layout, and NEW is the desired
2384
   form.  OLD is updated to reflect the code emitted, i.e., it will be
2385
   the same as NEW upon return.
2386
 
2387
   This function will not preserve block_end[].  But that information
2388
   is no longer needed once this has executed.  */
2389
 
2390
static void
2391
change_stack (rtx insn, stack old, stack new_stack, enum emit_where where)
2392
{
2393
  int reg;
2394
  int update_end = 0;
2395
  int i;
2396
 
2397
  /* Stack adjustments for the first insn in a block update the
2398
     current_block's stack_in instead of inserting insns directly.
2399
     compensate_edges will add the necessary code later.  */
2400
  if (current_block
2401
      && starting_stack_p
2402
      && where == EMIT_BEFORE)
2403
    {
2404
      BLOCK_INFO (current_block)->stack_in = *new_stack;
2405
      starting_stack_p = false;
2406
      *old = *new_stack;
2407
      return;
2408
    }
2409
 
2410
  /* We will be inserting new insns "backwards".  If we are to insert
2411
     after INSN, find the next insn, and insert before it.  */
2412
 
2413
  if (where == EMIT_AFTER)
2414
    {
2415
      if (current_block && BB_END (current_block) == insn)
2416
        update_end = 1;
2417
      insn = NEXT_INSN (insn);
2418
    }
2419
 
2420
  /* Initialize partially dead variables.  */
2421
  for (i = FIRST_STACK_REG; i < LAST_STACK_REG + 1; i++)
2422
    if (TEST_HARD_REG_BIT (new_stack->reg_set, i)
2423
        && !TEST_HARD_REG_BIT (old->reg_set, i))
2424
      {
2425
        old->reg[++old->top] = i;
2426
        SET_HARD_REG_BIT (old->reg_set, i);
2427
        emit_insn_before (gen_rtx_SET (VOIDmode,
2428
                                       FP_MODE_REG (i, SFmode), not_a_num), insn);
2429
      }
2430
 
2431
  /* Pop any registers that are not needed in the new block.  */
2432
 
2433
  /* If the destination block's stack already has a specified layout
2434
     and contains two or more registers, use a more intelligent algorithm
2435
     to pop registers that minimizes the number number of fxchs below.  */
2436
  if (new_stack->top > 0)
2437
    {
2438
      bool slots[REG_STACK_SIZE];
2439
      int pops[REG_STACK_SIZE];
2440
      int next, dest, topsrc;
2441
 
2442
      /* First pass to determine the free slots.  */
2443
      for (reg = 0; reg <= new_stack->top; reg++)
2444
        slots[reg] = TEST_HARD_REG_BIT (new_stack->reg_set, old->reg[reg]);
2445
 
2446
      /* Second pass to allocate preferred slots.  */
2447
      topsrc = -1;
2448
      for (reg = old->top; reg > new_stack->top; reg--)
2449
        if (TEST_HARD_REG_BIT (new_stack->reg_set, old->reg[reg]))
2450
          {
2451
            dest = -1;
2452
            for (next = 0; next <= new_stack->top; next++)
2453
              if (!slots[next] && new_stack->reg[next] == old->reg[reg])
2454
                {
2455
                  /* If this is a preference for the new top of stack, record
2456
                     the fact by remembering it's old->reg in topsrc.  */
2457
                  if (next == new_stack->top)
2458
                    topsrc = reg;
2459
                  slots[next] = true;
2460
                  dest = next;
2461
                  break;
2462
                }
2463
            pops[reg] = dest;
2464
          }
2465
        else
2466
          pops[reg] = reg;
2467
 
2468
      /* Intentionally, avoid placing the top of stack in it's correct
2469
         location, if we still need to permute the stack below and we
2470
         can usefully place it somewhere else.  This is the case if any
2471
         slot is still unallocated, in which case we should place the
2472
         top of stack there.  */
2473
      if (topsrc != -1)
2474
        for (reg = 0; reg < new_stack->top; reg++)
2475
          if (!slots[reg])
2476
            {
2477
              pops[topsrc] = reg;
2478
              slots[new_stack->top] = false;
2479
              slots[reg] = true;
2480
              break;
2481
            }
2482
 
2483
      /* Third pass allocates remaining slots and emits pop insns.  */
2484
      next = new_stack->top;
2485
      for (reg = old->top; reg > new_stack->top; reg--)
2486
        {
2487
          dest = pops[reg];
2488
          if (dest == -1)
2489
            {
2490
              /* Find next free slot.  */
2491
              while (slots[next])
2492
                next--;
2493
              dest = next--;
2494
            }
2495
          emit_pop_insn (insn, old, FP_MODE_REG (old->reg[dest], DFmode),
2496
                         EMIT_BEFORE);
2497
        }
2498
    }
2499
  else
2500
    {
2501
      /* The following loop attempts to maximize the number of times we
2502
         pop the top of the stack, as this permits the use of the faster
2503
         ffreep instruction on platforms that support it.  */
2504
      int live, next;
2505
 
2506
      live = 0;
2507
      for (reg = 0; reg <= old->top; reg++)
2508
        if (TEST_HARD_REG_BIT (new_stack->reg_set, old->reg[reg]))
2509
          live++;
2510
 
2511
      next = live;
2512
      while (old->top >= live)
2513
        if (TEST_HARD_REG_BIT (new_stack->reg_set, old->reg[old->top]))
2514
          {
2515
            while (TEST_HARD_REG_BIT (new_stack->reg_set, old->reg[next]))
2516
              next--;
2517
            emit_pop_insn (insn, old, FP_MODE_REG (old->reg[next], DFmode),
2518
                           EMIT_BEFORE);
2519
          }
2520
        else
2521
          emit_pop_insn (insn, old, FP_MODE_REG (old->reg[old->top], DFmode),
2522
                         EMIT_BEFORE);
2523
    }
2524
 
2525
  if (new_stack->top == -2)
2526
    {
2527
      /* If the new block has never been processed, then it can inherit
2528
         the old stack order.  */
2529
 
2530
      new_stack->top = old->top;
2531
      memcpy (new_stack->reg, old->reg, sizeof (new_stack->reg));
2532
    }
2533
  else
2534
    {
2535
      /* This block has been entered before, and we must match the
2536
         previously selected stack order.  */
2537
 
2538
      /* By now, the only difference should be the order of the stack,
2539
         not their depth or liveliness.  */
2540
 
2541
      gcc_assert (hard_reg_set_equal_p (old->reg_set, new_stack->reg_set));
2542
      gcc_assert (old->top == new_stack->top);
2543
 
2544
      /* If the stack is not empty (new_stack->top != -1), loop here emitting
2545
         swaps until the stack is correct.
2546
 
2547
         The worst case number of swaps emitted is N + 2, where N is the
2548
         depth of the stack.  In some cases, the reg at the top of
2549
         stack may be correct, but swapped anyway in order to fix
2550
         other regs.  But since we never swap any other reg away from
2551
         its correct slot, this algorithm will converge.  */
2552
 
2553
      if (new_stack->top != -1)
2554
        do
2555
          {
2556
            /* Swap the reg at top of stack into the position it is
2557
               supposed to be in, until the correct top of stack appears.  */
2558
 
2559
            while (old->reg[old->top] != new_stack->reg[new_stack->top])
2560
              {
2561
                for (reg = new_stack->top; reg >= 0; reg--)
2562
                  if (new_stack->reg[reg] == old->reg[old->top])
2563
                    break;
2564
 
2565
                gcc_assert (reg != -1);
2566
 
2567
                emit_swap_insn (insn, old,
2568
                                FP_MODE_REG (old->reg[reg], DFmode));
2569
              }
2570
 
2571
            /* See if any regs remain incorrect.  If so, bring an
2572
             incorrect reg to the top of stack, and let the while loop
2573
             above fix it.  */
2574
 
2575
            for (reg = new_stack->top; reg >= 0; reg--)
2576
              if (new_stack->reg[reg] != old->reg[reg])
2577
                {
2578
                  emit_swap_insn (insn, old,
2579
                                  FP_MODE_REG (old->reg[reg], DFmode));
2580
                  break;
2581
                }
2582
          } while (reg >= 0);
2583
 
2584
      /* At this point there must be no differences.  */
2585
 
2586
      for (reg = old->top; reg >= 0; reg--)
2587
        gcc_assert (old->reg[reg] == new_stack->reg[reg]);
2588
    }
2589
 
2590
  if (update_end)
2591
    BB_END (current_block) = PREV_INSN (insn);
2592
}
2593
 
2594
/* Print stack configuration.  */
2595
 
2596
static void
2597
print_stack (FILE *file, stack s)
2598
{
2599
  if (! file)
2600
    return;
2601
 
2602
  if (s->top == -2)
2603
    fprintf (file, "uninitialized\n");
2604
  else if (s->top == -1)
2605
    fprintf (file, "empty\n");
2606
  else
2607
    {
2608
      int i;
2609
      fputs ("[ ", file);
2610
      for (i = 0; i <= s->top; ++i)
2611
        fprintf (file, "%d ", s->reg[i]);
2612
      fputs ("]\n", file);
2613
    }
2614
}
2615
 
2616
/* This function was doing life analysis.  We now let the regular live
2617
   code do it's job, so we only need to check some extra invariants
2618
   that reg-stack expects.  Primary among these being that all registers
2619
   are initialized before use.
2620
 
2621
   The function returns true when code was emitted to CFG edges and
2622
   commit_edge_insertions needs to be called.  */
2623
 
2624
static int
2625
convert_regs_entry (void)
2626
{
2627
  int inserted = 0;
2628
  edge e;
2629
  edge_iterator ei;
2630
 
2631
  /* Load something into each stack register live at function entry.
2632
     Such live registers can be caused by uninitialized variables or
2633
     functions not returning values on all paths.  In order to keep
2634
     the push/pop code happy, and to not scrog the register stack, we
2635
     must put something in these registers.  Use a QNaN.
2636
 
2637
     Note that we are inserting converted code here.  This code is
2638
     never seen by the convert_regs pass.  */
2639
 
2640
  FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2641
    {
2642
      basic_block block = e->dest;
2643
      block_info bi = BLOCK_INFO (block);
2644
      int reg, top = -1;
2645
 
2646
      for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2647
        if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2648
          {
2649
            rtx init;
2650
 
2651
            bi->stack_in.reg[++top] = reg;
2652
 
2653
            init = gen_rtx_SET (VOIDmode,
2654
                                FP_MODE_REG (FIRST_STACK_REG, SFmode),
2655
                                not_a_num);
2656
            insert_insn_on_edge (init, e);
2657
            inserted = 1;
2658
          }
2659
 
2660
      bi->stack_in.top = top;
2661
    }
2662
 
2663
  return inserted;
2664
}
2665
 
2666
/* Construct the desired stack for function exit.  This will either
2667
   be `empty', or the function return value at top-of-stack.  */
2668
 
2669
static void
2670
convert_regs_exit (void)
2671
{
2672
  int value_reg_low, value_reg_high;
2673
  stack output_stack;
2674
  rtx retvalue;
2675
 
2676
  retvalue = stack_result (current_function_decl);
2677
  value_reg_low = value_reg_high = -1;
2678
  if (retvalue)
2679
    {
2680
      value_reg_low = REGNO (retvalue);
2681
      value_reg_high = END_HARD_REGNO (retvalue) - 1;
2682
    }
2683
 
2684
  output_stack = &BLOCK_INFO (EXIT_BLOCK_PTR)->stack_in;
2685
  if (value_reg_low == -1)
2686
    output_stack->top = -1;
2687
  else
2688
    {
2689
      int reg;
2690
 
2691
      output_stack->top = value_reg_high - value_reg_low;
2692
      for (reg = value_reg_low; reg <= value_reg_high; ++reg)
2693
        {
2694
          output_stack->reg[value_reg_high - reg] = reg;
2695
          SET_HARD_REG_BIT (output_stack->reg_set, reg);
2696
        }
2697
    }
2698
}
2699
 
2700
/* Copy the stack info from the end of edge E's source block to the
2701
   start of E's destination block.  */
2702
 
2703
static void
2704
propagate_stack (edge e)
2705
{
2706
  stack src_stack = &BLOCK_INFO (e->src)->stack_out;
2707
  stack dest_stack = &BLOCK_INFO (e->dest)->stack_in;
2708
  int reg;
2709
 
2710
  /* Preserve the order of the original stack, but check whether
2711
     any pops are needed.  */
2712
  dest_stack->top = -1;
2713
  for (reg = 0; reg <= src_stack->top; ++reg)
2714
    if (TEST_HARD_REG_BIT (dest_stack->reg_set, src_stack->reg[reg]))
2715
      dest_stack->reg[++dest_stack->top] = src_stack->reg[reg];
2716
 
2717
  /* Push in any partially dead values.  */
2718
  for (reg = FIRST_STACK_REG; reg < LAST_STACK_REG + 1; reg++)
2719
    if (TEST_HARD_REG_BIT (dest_stack->reg_set, reg)
2720
        && !TEST_HARD_REG_BIT (src_stack->reg_set, reg))
2721
      dest_stack->reg[++dest_stack->top] = reg;
2722
}
2723
 
2724
 
2725
/* Adjust the stack of edge E's source block on exit to match the stack
2726
   of it's target block upon input.  The stack layouts of both blocks
2727
   should have been defined by now.  */
2728
 
2729
static bool
2730
compensate_edge (edge e)
2731
{
2732
  basic_block source = e->src, target = e->dest;
2733
  stack target_stack = &BLOCK_INFO (target)->stack_in;
2734
  stack source_stack = &BLOCK_INFO (source)->stack_out;
2735
  struct stack_def regstack;
2736
  int reg;
2737
 
2738
  if (dump_file)
2739
    fprintf (dump_file, "Edge %d->%d: ", source->index, target->index);
2740
 
2741
  gcc_assert (target_stack->top != -2);
2742
 
2743
  /* Check whether stacks are identical.  */
2744
  if (target_stack->top == source_stack->top)
2745
    {
2746
      for (reg = target_stack->top; reg >= 0; --reg)
2747
        if (target_stack->reg[reg] != source_stack->reg[reg])
2748
          break;
2749
 
2750
      if (reg == -1)
2751
        {
2752
          if (dump_file)
2753
            fprintf (dump_file, "no changes needed\n");
2754
          return false;
2755
        }
2756
    }
2757
 
2758
  if (dump_file)
2759
    {
2760
      fprintf (dump_file, "correcting stack to ");
2761
      print_stack (dump_file, target_stack);
2762
    }
2763
 
2764
  /* Abnormal calls may appear to have values live in st(0), but the
2765
     abnormal return path will not have actually loaded the values.  */
2766
  if (e->flags & EDGE_ABNORMAL_CALL)
2767
    {
2768
      /* Assert that the lifetimes are as we expect -- one value
2769
         live at st(0) on the end of the source block, and no
2770
         values live at the beginning of the destination block.
2771
         For complex return values, we may have st(1) live as well.  */
2772
      gcc_assert (source_stack->top == 0 || source_stack->top == 1);
2773
      gcc_assert (target_stack->top == -1);
2774
      return false;
2775
    }
2776
 
2777
  /* Handle non-call EH edges specially.  The normal return path have
2778
     values in registers.  These will be popped en masse by the unwind
2779
     library.  */
2780
  if (e->flags & EDGE_EH)
2781
    {
2782
      gcc_assert (target_stack->top == -1);
2783
      return false;
2784
    }
2785
 
2786
  /* We don't support abnormal edges.  Global takes care to
2787
     avoid any live register across them, so we should never
2788
     have to insert instructions on such edges.  */
2789
  gcc_assert (! (e->flags & EDGE_ABNORMAL));
2790
 
2791
  /* Make a copy of source_stack as change_stack is destructive.  */
2792
  regstack = *source_stack;
2793
 
2794
  /* It is better to output directly to the end of the block
2795
     instead of to the edge, because emit_swap can do minimal
2796
     insn scheduling.  We can do this when there is only one
2797
     edge out, and it is not abnormal.  */
2798
  if (EDGE_COUNT (source->succs) == 1)
2799
    {
2800
      current_block = source;
2801
      change_stack (BB_END (source), &regstack, target_stack,
2802
                    (JUMP_P (BB_END (source)) ? EMIT_BEFORE : EMIT_AFTER));
2803
    }
2804
  else
2805
    {
2806
      rtx seq, after;
2807
 
2808
      current_block = NULL;
2809
      start_sequence ();
2810
 
2811
      /* ??? change_stack needs some point to emit insns after.  */
2812
      after = emit_note (NOTE_INSN_DELETED);
2813
 
2814
      change_stack (after, &regstack, target_stack, EMIT_BEFORE);
2815
 
2816
      seq = get_insns ();
2817
      end_sequence ();
2818
 
2819
      insert_insn_on_edge (seq, e);
2820
      return true;
2821
    }
2822
  return false;
2823
}
2824
 
2825
/* Traverse all non-entry edges in the CFG, and emit the necessary
2826
   edge compensation code to change the stack from stack_out of the
2827
   source block to the stack_in of the destination block.  */
2828
 
2829
static bool
2830
compensate_edges (void)
2831
{
2832
  bool inserted = false;
2833
  basic_block bb;
2834
 
2835
  starting_stack_p = false;
2836
 
2837
  FOR_EACH_BB (bb)
2838
    if (bb != ENTRY_BLOCK_PTR)
2839
      {
2840
        edge e;
2841
        edge_iterator ei;
2842
 
2843
        FOR_EACH_EDGE (e, ei, bb->succs)
2844
          inserted |= compensate_edge (e);
2845
      }
2846
  return inserted;
2847
}
2848
 
2849
/* Select the better of two edges E1 and E2 to use to determine the
2850
   stack layout for their shared destination basic block.  This is
2851
   typically the more frequently executed.  The edge E1 may be NULL
2852
   (in which case E2 is returned), but E2 is always non-NULL.  */
2853
 
2854
static edge
2855
better_edge (edge e1, edge e2)
2856
{
2857
  if (!e1)
2858
    return e2;
2859
 
2860
  if (EDGE_FREQUENCY (e1) > EDGE_FREQUENCY (e2))
2861
    return e1;
2862
  if (EDGE_FREQUENCY (e1) < EDGE_FREQUENCY (e2))
2863
    return e2;
2864
 
2865
  if (e1->count > e2->count)
2866
    return e1;
2867
  if (e1->count < e2->count)
2868
    return e2;
2869
 
2870
  /* Prefer critical edges to minimize inserting compensation code on
2871
     critical edges.  */
2872
 
2873
  if (EDGE_CRITICAL_P (e1) != EDGE_CRITICAL_P (e2))
2874
    return EDGE_CRITICAL_P (e1) ? e1 : e2;
2875
 
2876
  /* Avoid non-deterministic behavior.  */
2877
  return (e1->src->index < e2->src->index) ? e1 : e2;
2878
}
2879
 
2880
/* Convert stack register references in one block.  */
2881
 
2882
static void
2883
convert_regs_1 (basic_block block)
2884
{
2885
  struct stack_def regstack;
2886
  block_info bi = BLOCK_INFO (block);
2887
  int reg;
2888
  rtx insn, next;
2889
  bool control_flow_insn_deleted = false;
2890
  int debug_insns_with_starting_stack = 0;
2891
 
2892
  any_malformed_asm = false;
2893
 
2894
  /* Choose an initial stack layout, if one hasn't already been chosen.  */
2895
  if (bi->stack_in.top == -2)
2896
    {
2897
      edge e, beste = NULL;
2898
      edge_iterator ei;
2899
 
2900
      /* Select the best incoming edge (typically the most frequent) to
2901
         use as a template for this basic block.  */
2902
      FOR_EACH_EDGE (e, ei, block->preds)
2903
        if (BLOCK_INFO (e->src)->done)
2904
          beste = better_edge (beste, e);
2905
 
2906
      if (beste)
2907
        propagate_stack (beste);
2908
      else
2909
        {
2910
          /* No predecessors.  Create an arbitrary input stack.  */
2911
          bi->stack_in.top = -1;
2912
          for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg)
2913
            if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg))
2914
              bi->stack_in.reg[++bi->stack_in.top] = reg;
2915
        }
2916
    }
2917
 
2918
  if (dump_file)
2919
    {
2920
      fprintf (dump_file, "\nBasic block %d\nInput stack: ", block->index);
2921
      print_stack (dump_file, &bi->stack_in);
2922
    }
2923
 
2924
  /* Process all insns in this block.  Keep track of NEXT so that we
2925
     don't process insns emitted while substituting in INSN.  */
2926
  current_block = block;
2927
  next = BB_HEAD (block);
2928
  regstack = bi->stack_in;
2929
  starting_stack_p = true;
2930
 
2931
  do
2932
    {
2933
      insn = next;
2934
      next = NEXT_INSN (insn);
2935
 
2936
      /* Ensure we have not missed a block boundary.  */
2937
      gcc_assert (next);
2938
      if (insn == BB_END (block))
2939
        next = NULL;
2940
 
2941
      /* Don't bother processing unless there is a stack reg
2942
         mentioned or if it's a CALL_INSN.  */
2943
      if (DEBUG_INSN_P (insn))
2944
        {
2945
          if (starting_stack_p)
2946
            debug_insns_with_starting_stack++;
2947
          else
2948
            {
2949
              for_each_rtx (&PATTERN (insn), subst_stack_regs_in_debug_insn,
2950
                            &regstack);
2951
 
2952
              /* Nothing must ever die at a debug insn.  If something
2953
                 is referenced in it that becomes dead, it should have
2954
                 died before and the reference in the debug insn
2955
                 should have been removed so as to avoid changing code
2956
                 generation.  */
2957
              gcc_assert (!find_reg_note (insn, REG_DEAD, NULL));
2958
            }
2959
        }
2960
      else if (stack_regs_mentioned (insn)
2961
               || CALL_P (insn))
2962
        {
2963
          if (dump_file)
2964
            {
2965
              fprintf (dump_file, "  insn %d input stack: ",
2966
                       INSN_UID (insn));
2967
              print_stack (dump_file, &regstack);
2968
            }
2969
          control_flow_insn_deleted |= subst_stack_regs (insn, &regstack);
2970
          starting_stack_p = false;
2971
        }
2972
    }
2973
  while (next);
2974
 
2975
  if (debug_insns_with_starting_stack)
2976
    {
2977
      /* Since it's the first non-debug instruction that determines
2978
         the stack requirements of the current basic block, we refrain
2979
         from updating debug insns before it in the loop above, and
2980
         fix them up here.  */
2981
      for (insn = BB_HEAD (block); debug_insns_with_starting_stack;
2982
           insn = NEXT_INSN (insn))
2983
        {
2984
          if (!DEBUG_INSN_P (insn))
2985
            continue;
2986
 
2987
          debug_insns_with_starting_stack--;
2988
          for_each_rtx (&PATTERN (insn), subst_stack_regs_in_debug_insn,
2989
                        &bi->stack_in);
2990
        }
2991
    }
2992
 
2993
  if (dump_file)
2994
    {
2995
      fprintf (dump_file, "Expected live registers [");
2996
      for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
2997
        if (TEST_HARD_REG_BIT (bi->out_reg_set, reg))
2998
          fprintf (dump_file, " %d", reg);
2999
      fprintf (dump_file, " ]\nOutput stack: ");
3000
      print_stack (dump_file, &regstack);
3001
    }
3002
 
3003
  insn = BB_END (block);
3004
  if (JUMP_P (insn))
3005
    insn = PREV_INSN (insn);
3006
 
3007
  /* If the function is declared to return a value, but it returns one
3008
     in only some cases, some registers might come live here.  Emit
3009
     necessary moves for them.  */
3010
 
3011
  for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; ++reg)
3012
    {
3013
      if (TEST_HARD_REG_BIT (bi->out_reg_set, reg)
3014
          && ! TEST_HARD_REG_BIT (regstack.reg_set, reg))
3015
        {
3016
          rtx set;
3017
 
3018
          if (dump_file)
3019
            fprintf (dump_file, "Emitting insn initializing reg %d\n", reg);
3020
 
3021
          set = gen_rtx_SET (VOIDmode, FP_MODE_REG (reg, SFmode), not_a_num);
3022
          insn = emit_insn_after (set, insn);
3023
          control_flow_insn_deleted |= subst_stack_regs (insn, &regstack);
3024
        }
3025
    }
3026
 
3027
  /* Amongst the insns possibly deleted during the substitution process above,
3028
     might have been the only trapping insn in the block.  We purge the now
3029
     possibly dead EH edges here to avoid an ICE from fixup_abnormal_edges,
3030
     called at the end of convert_regs.  The order in which we process the
3031
     blocks ensures that we never delete an already processed edge.
3032
 
3033
     Note that, at this point, the CFG may have been damaged by the emission
3034
     of instructions after an abnormal call, which moves the basic block end
3035
     (and is the reason why we call fixup_abnormal_edges later).  So we must
3036
     be sure that the trapping insn has been deleted before trying to purge
3037
     dead edges, otherwise we risk purging valid edges.
3038
 
3039
     ??? We are normally supposed not to delete trapping insns, so we pretend
3040
     that the insns deleted above don't actually trap.  It would have been
3041
     better to detect this earlier and avoid creating the EH edge in the first
3042
     place, still, but we don't have enough information at that time.  */
3043
 
3044
  if (control_flow_insn_deleted)
3045
    purge_dead_edges (block);
3046
 
3047
  /* Something failed if the stack lives don't match.  If we had malformed
3048
     asms, we zapped the instruction itself, but that didn't produce the
3049
     same pattern of register kills as before.  */
3050
 
3051
  gcc_assert (hard_reg_set_equal_p (regstack.reg_set, bi->out_reg_set)
3052
              || any_malformed_asm);
3053
  bi->stack_out = regstack;
3054
  bi->done = true;
3055
}
3056
 
3057
/* Convert registers in all blocks reachable from BLOCK.  */
3058
 
3059
static void
3060
convert_regs_2 (basic_block block)
3061
{
3062
  basic_block *stack, *sp;
3063
 
3064
  /* We process the blocks in a top-down manner, in a way such that one block
3065
     is only processed after all its predecessors.  The number of predecessors
3066
     of every block has already been computed.  */
3067
 
3068
  stack = XNEWVEC (basic_block, n_basic_blocks);
3069
  sp = stack;
3070
 
3071
  *sp++ = block;
3072
 
3073
  do
3074
    {
3075
      edge e;
3076
      edge_iterator ei;
3077
 
3078
      block = *--sp;
3079
 
3080
      /* Processing BLOCK is achieved by convert_regs_1, which may purge
3081
         some dead EH outgoing edge after the deletion of the trapping
3082
         insn inside the block.  Since the number of predecessors of
3083
         BLOCK's successors was computed based on the initial edge set,
3084
         we check the necessity to process some of these successors
3085
         before such an edge deletion may happen.  However, there is
3086
         a pitfall: if BLOCK is the only predecessor of a successor and
3087
         the edge between them happens to be deleted, the successor
3088
         becomes unreachable and should not be processed.  The problem
3089
         is that there is no way to preventively detect this case so we
3090
         stack the successor in all cases and hand over the task of
3091
         fixing up the discrepancy to convert_regs_1.  */
3092
 
3093
      FOR_EACH_EDGE (e, ei, block->succs)
3094
        if (! (e->flags & EDGE_DFS_BACK))
3095
          {
3096
            BLOCK_INFO (e->dest)->predecessors--;
3097
            if (!BLOCK_INFO (e->dest)->predecessors)
3098
              *sp++ = e->dest;
3099
          }
3100
 
3101
      convert_regs_1 (block);
3102
    }
3103
  while (sp != stack);
3104
 
3105
  free (stack);
3106
}
3107
 
3108
/* Traverse all basic blocks in a function, converting the register
3109
   references in each insn from the "flat" register file that gcc uses,
3110
   to the stack-like registers the 387 uses.  */
3111
 
3112
static void
3113
convert_regs (void)
3114
{
3115
  int inserted;
3116
  basic_block b;
3117
  edge e;
3118
  edge_iterator ei;
3119
 
3120
  /* Initialize uninitialized registers on function entry.  */
3121
  inserted = convert_regs_entry ();
3122
 
3123
  /* Construct the desired stack for function exit.  */
3124
  convert_regs_exit ();
3125
  BLOCK_INFO (EXIT_BLOCK_PTR)->done = 1;
3126
 
3127
  /* ??? Future: process inner loops first, and give them arbitrary
3128
     initial stacks which emit_swap_insn can modify.  This ought to
3129
     prevent double fxch that often appears at the head of a loop.  */
3130
 
3131
  /* Process all blocks reachable from all entry points.  */
3132
  FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3133
    convert_regs_2 (e->dest);
3134
 
3135
  /* ??? Process all unreachable blocks.  Though there's no excuse
3136
     for keeping these even when not optimizing.  */
3137
  FOR_EACH_BB (b)
3138
    {
3139
      block_info bi = BLOCK_INFO (b);
3140
 
3141
      if (! bi->done)
3142
        convert_regs_2 (b);
3143
    }
3144
 
3145
  inserted |= compensate_edges ();
3146
 
3147
  clear_aux_for_blocks ();
3148
 
3149
  fixup_abnormal_edges ();
3150
  if (inserted)
3151
    commit_edge_insertions ();
3152
 
3153
  if (dump_file)
3154
    fputc ('\n', dump_file);
3155
}
3156
 
3157
/* Convert register usage from "flat" register file usage to a "stack
3158
   register file.  FILE is the dump file, if used.
3159
 
3160
   Construct a CFG and run life analysis.  Then convert each insn one
3161
   by one.  Run a last cleanup_cfg pass, if optimizing, to eliminate
3162
   code duplication created when the converter inserts pop insns on
3163
   the edges.  */
3164
 
3165
static bool
3166
reg_to_stack (void)
3167
{
3168
  basic_block bb;
3169
  int i;
3170
  int max_uid;
3171
 
3172
  /* Clean up previous run.  */
3173
  if (stack_regs_mentioned_data != NULL)
3174
    VEC_free (char, heap, stack_regs_mentioned_data);
3175
 
3176
  /* See if there is something to do.  Flow analysis is quite
3177
     expensive so we might save some compilation time.  */
3178
  for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
3179
    if (df_regs_ever_live_p (i))
3180
      break;
3181
  if (i > LAST_STACK_REG)
3182
    return false;
3183
 
3184
  df_note_add_problem ();
3185
  df_analyze ();
3186
 
3187
  mark_dfs_back_edges ();
3188
 
3189
  /* Set up block info for each basic block.  */
3190
  alloc_aux_for_blocks (sizeof (struct block_info_def));
3191
  FOR_EACH_BB (bb)
3192
    {
3193
      block_info bi = BLOCK_INFO (bb);
3194
      edge_iterator ei;
3195
      edge e;
3196
      int reg;
3197
 
3198
      FOR_EACH_EDGE (e, ei, bb->preds)
3199
        if (!(e->flags & EDGE_DFS_BACK)
3200
            && e->src != ENTRY_BLOCK_PTR)
3201
          bi->predecessors++;
3202
 
3203
      /* Set current register status at last instruction `uninitialized'.  */
3204
      bi->stack_in.top = -2;
3205
 
3206
      /* Copy live_at_end and live_at_start into temporaries.  */
3207
      for (reg = FIRST_STACK_REG; reg <= LAST_STACK_REG; reg++)
3208
        {
3209
          if (REGNO_REG_SET_P (DF_LR_OUT (bb), reg))
3210
            SET_HARD_REG_BIT (bi->out_reg_set, reg);
3211
          if (REGNO_REG_SET_P (DF_LR_IN (bb), reg))
3212
            SET_HARD_REG_BIT (bi->stack_in.reg_set, reg);
3213
        }
3214
    }
3215
 
3216
  /* Create the replacement registers up front.  */
3217
  for (i = FIRST_STACK_REG; i <= LAST_STACK_REG; i++)
3218
    {
3219
      enum machine_mode mode;
3220
      for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT);
3221
           mode != VOIDmode;
3222
           mode = GET_MODE_WIDER_MODE (mode))
3223
        FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
3224
      for (mode = GET_CLASS_NARROWEST_MODE (MODE_COMPLEX_FLOAT);
3225
           mode != VOIDmode;
3226
           mode = GET_MODE_WIDER_MODE (mode))
3227
        FP_MODE_REG (i, mode) = gen_rtx_REG (mode, i);
3228
    }
3229
 
3230
  ix86_flags_rtx = gen_rtx_REG (CCmode, FLAGS_REG);
3231
 
3232
  /* A QNaN for initializing uninitialized variables.
3233
 
3234
     ??? We can't load from constant memory in PIC mode, because
3235
     we're inserting these instructions before the prologue and
3236
     the PIC register hasn't been set up.  In that case, fall back
3237
     on zero, which we can get from `fldz'.  */
3238
 
3239
  if ((flag_pic && !TARGET_64BIT)
3240
      || ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC)
3241
    not_a_num = CONST0_RTX (SFmode);
3242
  else
3243
    {
3244
      REAL_VALUE_TYPE r;
3245
 
3246
      real_nan (&r, "", 1, SFmode);
3247
      not_a_num = CONST_DOUBLE_FROM_REAL_VALUE (r, SFmode);
3248
      not_a_num = force_const_mem (SFmode, not_a_num);
3249
    }
3250
 
3251
  /* Allocate a cache for stack_regs_mentioned.  */
3252
  max_uid = get_max_uid ();
3253
  stack_regs_mentioned_data = VEC_alloc (char, heap, max_uid + 1);
3254
  memset (VEC_address (char, stack_regs_mentioned_data),
3255
          0, sizeof (char) * (max_uid + 1));
3256
 
3257
  convert_regs ();
3258
 
3259
  free_aux_for_blocks ();
3260
  return true;
3261
}
3262
#endif /* STACK_REGS */
3263
 
3264
static bool
3265
gate_handle_stack_regs (void)
3266
{
3267
#ifdef STACK_REGS
3268
  return 1;
3269
#else
3270
  return 0;
3271
#endif
3272
}
3273
 
3274
struct rtl_opt_pass pass_stack_regs =
3275
{
3276
 {
3277
  RTL_PASS,
3278
  "*stack_regs",                        /* name */
3279
  gate_handle_stack_regs,               /* gate */
3280
  NULL,                                 /* execute */
3281
  NULL,                                 /* sub */
3282
  NULL,                                 /* next */
3283
  0,                                    /* static_pass_number */
3284
  TV_REG_STACK,                         /* tv_id */
3285
  0,                                    /* properties_required */
3286
  0,                                    /* properties_provided */
3287
  0,                                    /* properties_destroyed */
3288
  0,                                    /* todo_flags_start */
3289
 
3290
 }
3291
};
3292
 
3293
/* Convert register usage from flat register file usage to a stack
3294
   register file.  */
3295
static unsigned int
3296
rest_of_handle_stack_regs (void)
3297
{
3298
#ifdef STACK_REGS
3299
  reg_to_stack ();
3300
  regstack_completed = 1;
3301
#endif
3302
  return 0;
3303
}
3304
 
3305
struct rtl_opt_pass pass_stack_regs_run =
3306
{
3307
 {
3308
  RTL_PASS,
3309
  "stack",                              /* name */
3310
  NULL,                                 /* gate */
3311
  rest_of_handle_stack_regs,            /* execute */
3312
  NULL,                                 /* sub */
3313
  NULL,                                 /* next */
3314
  0,                                    /* static_pass_number */
3315
  TV_REG_STACK,                         /* tv_id */
3316
  0,                                    /* properties_required */
3317
  0,                                    /* properties_provided */
3318
  0,                                    /* properties_destroyed */
3319
  0,                                    /* todo_flags_start */
3320
  TODO_df_finish | TODO_verify_rtl_sharing |
3321
  TODO_dump_func |
3322
  TODO_ggc_collect                      /* todo_flags_finish */
3323
 }
3324
};

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