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[/] [openrisc/] [trunk/] [gnu-stable/] [gcc-4.5.1/] [gcc/] [tree-call-cdce.c] - Blame information for rev 847

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1 280 jeremybenn
/* Conditional Dead Call Elimination pass for the GNU compiler.
2
   Copyright (C) 2008
3
   Free Software Foundation, Inc.
4
   Contributed by Xinliang David Li <davidxl@google.com>
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 the
10
Free Software Foundation; either version 3, or (at your option) any
11
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 or
15
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
16
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
#include "config.h"
23
#include "system.h"
24
#include "coretypes.h"
25
#include "tm.h"
26
#include "ggc.h"
27
 
28
/* These RTL headers are needed for basic-block.h.  */
29
#include "rtl.h"
30
#include "tm_p.h"
31
#include "hard-reg-set.h"
32
#include "obstack.h"
33
#include "basic-block.h"
34
 
35
#include "tree.h"
36
#include "diagnostic.h"
37
#include "tree-flow.h"
38
#include "gimple.h"
39
#include "tree-dump.h"
40
#include "tree-pass.h"
41
#include "timevar.h"
42
#include "flags.h"
43
 
44
 
45
/* Conditional dead call elimination
46
 
47
   Some builtin functions can set errno on error conditions, but they
48
   are otherwise pure.  If the result of a call to such a function is
49
   not used, the compiler can still not eliminate the call without
50
   powerful interprocedural analysis to prove that the errno is not
51
   checked.  However, if the conditions under which the error occurs
52
   are known, the compiler can conditionally dead code eliminate the
53
   calls by shrink-wrapping the semi-dead calls into the error condition:
54
 
55
        built_in_call (args)
56
          ==>
57
        if (error_cond (args))
58
             built_in_call (args)
59
 
60
    An actual simple example is :
61
         log (x);   // Mostly dead call
62
     ==>
63
         if (x < 0)
64
             log (x);
65
     With this change, call to log (x) is effectively eliminated, as
66
     in majority of the cases, log won't be called with x out of
67
     range.  The branch is totally predictable, so the branch cost
68
     is low.
69
 
70
   Note that library functions are not supposed to clear errno to zero without
71
   error.  See IEEE Std 1003.1, section 2.3 Error Numbers, and section 7.5:3 of
72
   ISO/IEC 9899 (C99).
73
 
74
   The condition wrapping the builtin call is conservatively set to avoid too
75
   aggressive (wrong) shrink wrapping.  The optimization is called conditional
76
   dead call elimination because the call is eliminated under the condition
77
   that the input arguments would not lead to domain or range error (for
78
   instance when x <= 0 for a log (x) call), however the chances that the error
79
   condition is hit is very low (those builtin calls which are conditionally
80
   dead are usually part of the C++ abstraction penalty exposed after
81
   inlining).  */
82
 
83
 
84
/* A structure for representing input domain of
85
   a function argument in integer.  If the lower
86
   bound is -inf, has_lb is set to false.  If the
87
   upper bound is +inf, has_ub is false.
88
   is_lb_inclusive and is_ub_inclusive are flags
89
   to indicate if lb and ub value are inclusive
90
   respectively.  */
91
 
92
typedef struct input_domain
93
{
94
  int lb;
95
  int ub;
96
  bool has_lb;
97
  bool has_ub;
98
  bool is_lb_inclusive;
99
  bool is_ub_inclusive;
100
} inp_domain;
101
 
102
/* A helper function to construct and return an input
103
   domain object.  LB is the lower bound, HAS_LB is
104
   a boolean flag indicating if the lower bound exists,
105
   and LB_INCLUSIVE is a boolean flag indicating if the
106
   lower bound is inclusive or not.  UB, HAS_UB, and
107
   UB_INCLUSIVE have the same meaning, but for upper
108
   bound of the domain.  */
109
 
110
static inp_domain
111
get_domain (int lb, bool has_lb, bool lb_inclusive,
112
            int ub, bool has_ub, bool ub_inclusive)
113
{
114
  inp_domain domain;
115
  domain.lb = lb;
116
  domain.has_lb = has_lb;
117
  domain.is_lb_inclusive = lb_inclusive;
118
  domain.ub = ub;
119
  domain.has_ub = has_ub;
120
  domain.is_ub_inclusive = ub_inclusive;
121
  return domain;
122
}
123
 
124
/* A helper function to check the target format for the
125
   argument type. In this implementation, only IEEE formats
126
   are supported.  ARG is the call argument to be checked.
127
   Returns true if the format is supported.  To support other
128
   target formats,  function get_no_error_domain needs to be
129
   enhanced to have range bounds properly computed. Since
130
   the check is cheap (very small number of candidates
131
   to be checked), the result is not cached for each float type.  */
132
 
133
static bool
134
check_target_format (tree arg)
135
{
136
  tree type;
137
  enum machine_mode mode;
138
  const struct real_format *rfmt;
139
 
140
  type = TREE_TYPE (arg);
141
  mode = TYPE_MODE (type);
142
  rfmt = REAL_MODE_FORMAT (mode);
143
  if ((mode == SFmode
144
       && (rfmt == &ieee_single_format || rfmt == &mips_single_format
145
           || rfmt == &motorola_single_format))
146
      || (mode == DFmode
147
          && (rfmt == &ieee_double_format || rfmt == &mips_double_format
148
              || rfmt == &motorola_double_format))
149
      /* For long double, we can not really check XFmode
150
         which is only defined on intel platforms.
151
         Candidate pre-selection using builtin function
152
         code guarantees that we are checking formats
153
         for long double modes: double, quad, and extended.  */
154
      || (mode != SFmode && mode != DFmode
155
          && (rfmt == &ieee_quad_format
156
              || rfmt == &mips_quad_format
157
              || rfmt == &ieee_extended_motorola_format
158
              || rfmt == &ieee_extended_intel_96_format
159
              || rfmt == &ieee_extended_intel_128_format
160
              || rfmt == &ieee_extended_intel_96_round_53_format)))
161
    return true;
162
 
163
  return false;
164
}
165
 
166
 
167
/* A helper function to help select calls to pow that are suitable for
168
   conditional DCE transformation.  It looks for pow calls that can be
169
   guided with simple conditions.  Such calls either have constant base
170
   values or base values converted from integers.  Returns true if
171
   the pow call POW_CALL is a candidate.  */
172
 
173
/* The maximum integer bit size for base argument of a pow call
174
   that is suitable for shrink-wrapping transformation.  */
175
#define MAX_BASE_INT_BIT_SIZE 32
176
 
177
static bool
178
check_pow (gimple pow_call)
179
{
180
  tree base, expn;
181
  enum tree_code bc, ec;
182
 
183
  if (gimple_call_num_args (pow_call) != 2)
184
    return false;
185
 
186
  base = gimple_call_arg (pow_call, 0);
187
  expn = gimple_call_arg (pow_call, 1);
188
 
189
  if (!check_target_format (expn))
190
    return false;
191
 
192
  bc = TREE_CODE (base);
193
  ec = TREE_CODE (expn);
194
 
195
  /* Folding candidates are not interesting.
196
     Can actually assert that it is already folded.  */
197
  if (ec == REAL_CST && bc == REAL_CST)
198
    return false;
199
 
200
  if (bc == REAL_CST)
201
    {
202
      /* Only handle a fixed range of constant.  */
203
      REAL_VALUE_TYPE mv;
204
      REAL_VALUE_TYPE bcv = TREE_REAL_CST (base);
205
      if (REAL_VALUES_EQUAL (bcv, dconst1))
206
        return false;
207
      if (REAL_VALUES_LESS (bcv, dconst1))
208
        return false;
209
      real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, 0, 1);
210
      if (REAL_VALUES_LESS (mv, bcv))
211
        return false;
212
      return true;
213
    }
214
  else if (bc == SSA_NAME)
215
    {
216
      tree base_val0, base_var, type;
217
      gimple base_def;
218
      int bit_sz;
219
 
220
      /* Only handles cases where base value is converted
221
         from integer values.  */
222
      base_def = SSA_NAME_DEF_STMT (base);
223
      if (gimple_code (base_def) != GIMPLE_ASSIGN)
224
        return false;
225
 
226
      if (gimple_assign_rhs_code (base_def) != FLOAT_EXPR)
227
        return false;
228
      base_val0 = gimple_assign_rhs1 (base_def);
229
 
230
      base_var = SSA_NAME_VAR (base_val0);
231
      if (!DECL_P  (base_var))
232
        return false;
233
 
234
      type = TREE_TYPE (base_var);
235
      if (TREE_CODE (type) != INTEGER_TYPE)
236
        return false;
237
      bit_sz = TYPE_PRECISION (type);
238
      /* If the type of the base is too wide,
239
         the resulting shrink wrapping condition
240
         will be too conservative.  */
241
      if (bit_sz > MAX_BASE_INT_BIT_SIZE)
242
        return false;
243
 
244
      return true;
245
    }
246
  else
247
    return false;
248
}
249
 
250
/* A helper function to help select candidate function calls that are
251
   suitable for conditional DCE.  Candidate functions must have single
252
   valid input domain in this implementation except for pow (see check_pow).
253
   Returns true if the function call is a candidate.  */
254
 
255
static bool
256
check_builtin_call (gimple bcall)
257
{
258
  tree arg;
259
 
260
  arg = gimple_call_arg (bcall, 0);
261
  return check_target_format (arg);
262
}
263
 
264
/* A helper function to determine if a builtin function call is a
265
   candidate for conditional DCE.  Returns true if the builtin call
266
   is a candidate.  */
267
 
268
static bool
269
is_call_dce_candidate (gimple call)
270
{
271
  tree fn;
272
  enum built_in_function fnc;
273
 
274
  /* Only potentially dead calls are considered.  */
275
  if (gimple_call_lhs (call))
276
    return false;
277
 
278
  fn = gimple_call_fndecl (call);
279
  if (!fn
280
      || !DECL_BUILT_IN (fn)
281
      || (DECL_BUILT_IN_CLASS (fn) != BUILT_IN_NORMAL))
282
    return false;
283
 
284
  fnc = DECL_FUNCTION_CODE (fn);
285
  switch (fnc)
286
    {
287
    /* Trig functions.  */
288
    CASE_FLT_FN (BUILT_IN_ACOS):
289
    CASE_FLT_FN (BUILT_IN_ASIN):
290
    /* Hyperbolic functions.  */
291
    CASE_FLT_FN (BUILT_IN_ACOSH):
292
    CASE_FLT_FN (BUILT_IN_ATANH):
293
    CASE_FLT_FN (BUILT_IN_COSH):
294
    CASE_FLT_FN (BUILT_IN_SINH):
295
    /* Log functions.  */
296
    CASE_FLT_FN (BUILT_IN_LOG):
297
    CASE_FLT_FN (BUILT_IN_LOG2):
298
    CASE_FLT_FN (BUILT_IN_LOG10):
299
    CASE_FLT_FN (BUILT_IN_LOG1P):
300
    /* Exp functions.  */
301
    CASE_FLT_FN (BUILT_IN_EXP):
302
    CASE_FLT_FN (BUILT_IN_EXP2):
303
    CASE_FLT_FN (BUILT_IN_EXP10):
304
    CASE_FLT_FN (BUILT_IN_EXPM1):
305
    CASE_FLT_FN (BUILT_IN_POW10):
306
    /* Sqrt.  */
307
    CASE_FLT_FN (BUILT_IN_SQRT):
308
      return check_builtin_call (call);
309
    /* Special one: two argument pow.  */
310
    case BUILT_IN_POW:
311
      return check_pow (call);
312
    default:
313
      break;
314
    }
315
 
316
  return false;
317
}
318
 
319
 
320
/* A helper function to generate gimple statements for
321
   one bound comparison.  ARG is the call argument to
322
   be compared with the bound, LBUB is the bound value
323
   in integer, TCODE is the tree_code of the comparison,
324
   TEMP_NAME1/TEMP_NAME2 are names of the temporaries,
325
   CONDS is a vector holding the produced GIMPLE statements,
326
   and NCONDS points to the variable holding the number
327
   of logical comparisons.  CONDS is either empty or
328
   a list ended with a null tree.  */
329
 
330
static void
331
gen_one_condition (tree arg, int lbub,
332
                   enum tree_code tcode,
333
                   const char *temp_name1,
334
                   const char *temp_name2,
335
                   VEC (gimple, heap) *conds,
336
                   unsigned *nconds)
337
{
338
  tree lbub_real_cst, lbub_cst, float_type;
339
  tree temp, tempn, tempc, tempcn;
340
  gimple stmt1, stmt2, stmt3;
341
 
342
  float_type = TREE_TYPE (arg);
343
  lbub_cst = build_int_cst (integer_type_node, lbub);
344
  lbub_real_cst = build_real_from_int_cst (float_type, lbub_cst);
345
 
346
  temp = create_tmp_var (float_type, temp_name1);
347
  stmt1 = gimple_build_assign (temp, arg);
348
  tempn = make_ssa_name (temp, stmt1);
349
  gimple_assign_set_lhs (stmt1, tempn);
350
 
351
  tempc = create_tmp_var (boolean_type_node, temp_name2);
352
  stmt2 = gimple_build_assign (tempc,
353
                               fold_build2 (tcode,
354
                                            boolean_type_node,
355
                                            tempn, lbub_real_cst));
356
  tempcn = make_ssa_name (tempc, stmt2);
357
  gimple_assign_set_lhs (stmt2, tempcn);
358
 
359
  stmt3 = gimple_build_cond_from_tree (tempcn, NULL_TREE, NULL_TREE);
360
  VEC_quick_push (gimple, conds, stmt1);
361
  VEC_quick_push (gimple, conds, stmt2);
362
  VEC_quick_push (gimple, conds, stmt3);
363
  (*nconds)++;
364
}
365
 
366
/* A helper function to generate GIMPLE statements for
367
   out of input domain check.  ARG is the call argument
368
   to be runtime checked, DOMAIN holds the valid domain
369
   for the given function, CONDS points to the vector
370
   holding the result GIMPLE statements.  *NCONDS is
371
   the number of logical comparisons.  This function
372
   produces no more than two logical comparisons, one
373
   for lower bound check, one for upper bound check.  */
374
 
375
static void
376
gen_conditions_for_domain (tree arg, inp_domain domain,
377
                           VEC (gimple, heap) *conds,
378
                           unsigned *nconds)
379
{
380
  if (domain.has_lb)
381
    gen_one_condition (arg, domain.lb,
382
                       (domain.is_lb_inclusive
383
                        ? LT_EXPR : LE_EXPR),
384
                       "DCE_COND_LB", "DCE_COND_LB_TEST",
385
                       conds, nconds);
386
 
387
  if (domain.has_ub)
388
    {
389
      /* Now push a separator.  */
390
      if (domain.has_lb)
391
        VEC_quick_push (gimple, conds, NULL);
392
 
393
      gen_one_condition (arg, domain.ub,
394
                         (domain.is_ub_inclusive
395
                          ? GT_EXPR : GE_EXPR),
396
                         "DCE_COND_UB", "DCE_COND_UB_TEST",
397
                         conds, nconds);
398
    }
399
}
400
 
401
 
402
/* A helper function to generate condition
403
   code for the y argument in call pow (some_const, y).
404
   See candidate selection in check_pow.  Since the
405
   candidates' base values have a limited range,
406
   the guarded code generated for y are simple:
407
   if (y > max_y)
408
     pow (const, y);
409
   Note max_y can be computed separately for each
410
   const base, but in this implementation, we
411
   choose to compute it using the max base
412
   in the allowed range for the purpose of
413
   simplicity.  BASE is the constant base value,
414
   EXPN is the expression for the exponent argument,
415
   *CONDS is the vector to hold resulting statements,
416
   and *NCONDS is the number of logical conditions.  */
417
 
418
static void
419
gen_conditions_for_pow_cst_base (tree base, tree expn,
420
                                 VEC (gimple, heap) *conds,
421
                                 unsigned *nconds)
422
{
423
  inp_domain exp_domain;
424
  /* Validate the range of the base constant to make
425
     sure it is consistent with check_pow.  */
426
  REAL_VALUE_TYPE mv;
427
  REAL_VALUE_TYPE bcv = TREE_REAL_CST (base);
428
  gcc_assert (!REAL_VALUES_EQUAL (bcv, dconst1)
429
              && !REAL_VALUES_LESS (bcv, dconst1));
430
  real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, 0, 1);
431
  gcc_assert (!REAL_VALUES_LESS (mv, bcv));
432
 
433
  exp_domain = get_domain (0, false, false,
434
                           127, true, false);
435
 
436
  gen_conditions_for_domain (expn, exp_domain,
437
                             conds, nconds);
438
}
439
 
440
/* Generate error condition code for pow calls with
441
   non constant base values.  The candidates selected
442
   have their base argument value converted from
443
   integer (see check_pow) value (1, 2, 4 bytes), and
444
   the max exp value is computed based on the size
445
   of the integer type (i.e. max possible base value).
446
   The resulting input domain for exp argument is thus
447
   conservative (smaller than the max value allowed by
448
   the runtime value of the base).  BASE is the integer
449
   base value, EXPN is the expression for the exponent
450
   argument, *CONDS is the vector to hold resulting
451
   statements, and *NCONDS is the number of logical
452
   conditions.  */
453
 
454
static void
455
gen_conditions_for_pow_int_base (tree base, tree expn,
456
                                 VEC (gimple, heap) *conds,
457
                                 unsigned *nconds)
458
{
459
  gimple base_def;
460
  tree base_val0;
461
  tree base_var, int_type;
462
  tree temp, tempn;
463
  tree cst0;
464
  gimple stmt1, stmt2;
465
  int bit_sz, max_exp;
466
  inp_domain exp_domain;
467
 
468
  base_def = SSA_NAME_DEF_STMT (base);
469
  base_val0 = gimple_assign_rhs1 (base_def);
470
  base_var = SSA_NAME_VAR (base_val0);
471
  int_type = TREE_TYPE (base_var);
472
  bit_sz = TYPE_PRECISION (int_type);
473
  gcc_assert (bit_sz > 0
474
              && bit_sz <= MAX_BASE_INT_BIT_SIZE);
475
 
476
  /* Determine the max exp argument value according to
477
     the size of the base integer.  The max exp value
478
     is conservatively estimated assuming IEEE754 double
479
     precision format.  */
480
  if (bit_sz == 8)
481
    max_exp = 128;
482
  else if (bit_sz == 16)
483
    max_exp = 64;
484
  else
485
    {
486
      gcc_assert (bit_sz == MAX_BASE_INT_BIT_SIZE);
487
      max_exp = 32;
488
    }
489
 
490
  /* For pow ((double)x, y), generate the following conditions:
491
     cond 1:
492
     temp1 = x;
493
     if (temp1 <= 0)
494
 
495
     cond 2:
496
     temp2 = y;
497
     if (temp2 > max_exp_real_cst)  */
498
 
499
  /* Generate condition in reverse order -- first
500
     the condition for the exp argument.  */
501
 
502
  exp_domain = get_domain (0, false, false,
503
                           max_exp, true, true);
504
 
505
  gen_conditions_for_domain (expn, exp_domain,
506
                             conds, nconds);
507
 
508
  /* Now generate condition for the base argument.
509
     Note it does not use the helper function
510
     gen_conditions_for_domain because the base
511
     type is integer.  */
512
 
513
  /* Push a separator.  */
514
  VEC_quick_push (gimple, conds, NULL);
515
 
516
  temp = create_tmp_var (int_type, "DCE_COND1");
517
  cst0 = build_int_cst (int_type, 0);
518
  stmt1 = gimple_build_assign (temp, base_val0);
519
  tempn = make_ssa_name (temp, stmt1);
520
  gimple_assign_set_lhs (stmt1, tempn);
521
  stmt2 = gimple_build_cond (LE_EXPR, tempn, cst0, NULL_TREE, NULL_TREE);
522
 
523
  VEC_quick_push (gimple, conds, stmt1);
524
  VEC_quick_push (gimple, conds, stmt2);
525
  (*nconds)++;
526
}
527
 
528
/* Method to generate conditional statements for guarding conditionally
529
   dead calls to pow.  One or more statements can be generated for
530
   each logical condition.  Statement groups of different conditions
531
   are separated by a NULL tree and they are stored in the VEC
532
   conds.  The number of logical conditions are stored in *nconds.
533
 
534
   See C99 standard, 7.12.7.4:2, for description of pow (x, y).
535
   The precise condition for domain errors are complex.  In this
536
   implementation, a simplified (but conservative) valid domain
537
   for x and y are used: x is positive to avoid dom errors, while
538
   y is smaller than a upper bound (depending on x) to avoid range
539
   errors.  Runtime code is generated to check x (if not constant)
540
   and y against the valid domain.  If it is out, jump to the call,
541
   otherwise the call is bypassed.  POW_CALL is the call statement,
542
   *CONDS is a vector holding the resulting condition statements,
543
   and *NCONDS is the number of logical conditions.  */
544
 
545
static void
546
gen_conditions_for_pow (gimple pow_call, VEC (gimple, heap) *conds,
547
                        unsigned *nconds)
548
{
549
  tree base, expn;
550
  enum tree_code bc;
551
 
552
#ifdef ENABLE_CHECKING
553
  gcc_assert (check_pow (pow_call));
554
#endif
555
 
556
  *nconds = 0;
557
 
558
  base = gimple_call_arg (pow_call, 0);
559
  expn = gimple_call_arg (pow_call, 1);
560
 
561
  bc = TREE_CODE (base);
562
 
563
  if (bc == REAL_CST)
564
    gen_conditions_for_pow_cst_base (base, expn, conds, nconds);
565
  else if (bc == SSA_NAME)
566
    gen_conditions_for_pow_int_base (base, expn, conds, nconds);
567
  else
568
    gcc_unreachable ();
569
}
570
 
571
/* A helper routine to help computing the valid input domain
572
   for a builtin function.  See C99 7.12.7 for details.  In this
573
   implementation, we only handle single region domain.  The
574
   resulting region can be conservative (smaller) than the actual
575
   one and rounded to integers.  Some of the bounds are documented
576
   in the standard, while other limit constants are computed
577
   assuming IEEE floating point format (for SF and DF modes).
578
   Since IEEE only sets minimum requirements for long double format,
579
   different long double formats exist under different implementations
580
   (e.g, 64 bit double precision (DF), 80 bit double-extended
581
   precision (XF), and 128 bit quad precision (QF) ).  For simplicity,
582
   in this implementation, the computed bounds for long double assume
583
   64 bit format (DF), and are therefore conservative.  Another
584
   assumption is that single precision float type is always SF mode,
585
   and double type is DF mode.  This function is quite
586
   implementation specific, so it may not be suitable to be part of
587
   builtins.c.  This needs to be revisited later to see if it can
588
   be leveraged in x87 assembly expansion.  */
589
 
590
static inp_domain
591
get_no_error_domain (enum built_in_function fnc)
592
{
593
  switch (fnc)
594
    {
595
    /* Trig functions: return [-1, +1]  */
596
    CASE_FLT_FN (BUILT_IN_ACOS):
597
    CASE_FLT_FN (BUILT_IN_ASIN):
598
      return get_domain (-1, true, true,
599
                         1, true, true);
600
    /* Hyperbolic functions.  */
601
    CASE_FLT_FN (BUILT_IN_ACOSH):
602
      /* acosh: [1, +inf)  */
603
      return get_domain (1, true, true,
604
                         1, false, false);
605
    CASE_FLT_FN (BUILT_IN_ATANH):
606
      /* atanh: (-1, +1)  */
607
      return get_domain (-1, true, false,
608
                         1, true, false);
609
    case BUILT_IN_COSHF:
610
    case BUILT_IN_SINHF:
611
      /* coshf: (-89, +89)  */
612
      return get_domain (-89, true, false,
613
                         89, true, false);
614
    case BUILT_IN_COSH:
615
    case BUILT_IN_SINH:
616
    case BUILT_IN_COSHL:
617
    case BUILT_IN_SINHL:
618
      /* cosh: (-710, +710)  */
619
      return get_domain (-710, true, false,
620
                         710, true, false);
621
    /* Log functions: (0, +inf)  */
622
    CASE_FLT_FN (BUILT_IN_LOG):
623
    CASE_FLT_FN (BUILT_IN_LOG2):
624
    CASE_FLT_FN (BUILT_IN_LOG10):
625
      return get_domain (0, true, false,
626
                         0, false, false);
627
    CASE_FLT_FN (BUILT_IN_LOG1P):
628
      return get_domain (-1, true, false,
629
                         0, false, false);
630
    /* Exp functions.  */
631
    case BUILT_IN_EXPF:
632
    case BUILT_IN_EXPM1F:
633
      /* expf: (-inf, 88)  */
634
      return get_domain (-1, false, false,
635
                         88, true, false);
636
    case BUILT_IN_EXP:
637
    case BUILT_IN_EXPM1:
638
    case BUILT_IN_EXPL:
639
    case BUILT_IN_EXPM1L:
640
      /* exp: (-inf, 709)  */
641
      return get_domain (-1, false, false,
642
                         709, true, false);
643
    case BUILT_IN_EXP2F:
644
      /* exp2f: (-inf, 128)  */
645
      return get_domain (-1, false, false,
646
                         128, true, false);
647
    case BUILT_IN_EXP2:
648
    case BUILT_IN_EXP2L:
649
      /* exp2: (-inf, 1024)  */
650
      return get_domain (-1, false, false,
651
                         1024, true, false);
652
    case BUILT_IN_EXP10F:
653
    case BUILT_IN_POW10F:
654
      /* exp10f: (-inf, 38)  */
655
      return get_domain (-1, false, false,
656
                         38, true, false);
657
    case BUILT_IN_EXP10:
658
    case BUILT_IN_POW10:
659
    case BUILT_IN_EXP10L:
660
    case BUILT_IN_POW10L:
661
      /* exp10: (-inf, 308)  */
662
      return get_domain (-1, false, false,
663
                         308, true, false);
664
    /* sqrt: [0, +inf)  */
665
    CASE_FLT_FN (BUILT_IN_SQRT):
666
      return get_domain (0, true, true,
667
                         0, false, false);
668
    default:
669
      gcc_unreachable ();
670
    }
671
 
672
  gcc_unreachable ();
673
}
674
 
675
/* The function to generate shrink wrap conditions for a partially
676
   dead builtin call whose return value is not used anywhere,
677
   but has to be kept live due to potential error condition.
678
   BI_CALL is the builtin call, CONDS is the vector of statements
679
   for condition code, NCODES is the pointer to the number of
680
   logical conditions.  Statements belonging to different logical
681
   condition are separated by NULL tree in the vector.  */
682
 
683
static void
684
gen_shrink_wrap_conditions (gimple bi_call, VEC (gimple, heap) *conds,
685
                            unsigned int *nconds)
686
{
687
  gimple call;
688
  tree fn;
689
  enum built_in_function fnc;
690
 
691
  gcc_assert (nconds && conds);
692
  gcc_assert (VEC_length (gimple, conds) == 0);
693
  gcc_assert (is_gimple_call (bi_call));
694
 
695
  call = bi_call;
696
  fn = gimple_call_fndecl (call);
697
  gcc_assert (fn && DECL_BUILT_IN (fn));
698
  fnc = DECL_FUNCTION_CODE (fn);
699
  *nconds = 0;
700
 
701
  if (fnc == BUILT_IN_POW)
702
    gen_conditions_for_pow (call, conds, nconds);
703
  else
704
    {
705
      tree arg;
706
      inp_domain domain = get_no_error_domain (fnc);
707
      *nconds = 0;
708
      arg = gimple_call_arg (bi_call, 0);
709
      gen_conditions_for_domain (arg, domain, conds, nconds);
710
    }
711
 
712
  return;
713
}
714
 
715
 
716
/* Probability of the branch (to the call) is taken.  */
717
#define ERR_PROB 0.01
718
 
719
/* The function to shrink wrap a partially dead builtin call
720
   whose return value is not used anywhere, but has to be kept
721
   live due to potential error condition.  Returns true if the
722
   transformation actually happens.  */
723
 
724
static bool
725
shrink_wrap_one_built_in_call (gimple bi_call)
726
{
727
  gimple_stmt_iterator bi_call_bsi;
728
  basic_block bi_call_bb, join_tgt_bb, guard_bb, guard_bb0;
729
  edge join_tgt_in_edge_from_call, join_tgt_in_edge_fall_thru;
730
  edge bi_call_in_edge0, guard_bb_in_edge;
731
  VEC (gimple, heap) *conds;
732
  unsigned tn_cond_stmts, nconds;
733
  unsigned ci;
734
  gimple cond_expr = NULL;
735
  gimple cond_expr_start;
736
  tree bi_call_label_decl;
737
  gimple bi_call_label;
738
 
739
  conds = VEC_alloc (gimple, heap, 12);
740
  gen_shrink_wrap_conditions (bi_call, conds, &nconds);
741
 
742
  /* This can happen if the condition generator decides
743
     it is not beneficial to do the transformation.  Just
744
     return false and do not do any transformation for
745
     the call.  */
746
  if (nconds == 0)
747
    return false;
748
 
749
  bi_call_bb = gimple_bb (bi_call);
750
 
751
  /* Now find the join target bb -- split
752
     bi_call_bb if needed.  */
753
  bi_call_bsi = gsi_for_stmt (bi_call);
754
 
755
  join_tgt_in_edge_from_call = split_block (bi_call_bb, bi_call);
756
  bi_call_bsi = gsi_for_stmt (bi_call);
757
 
758
  join_tgt_bb = join_tgt_in_edge_from_call->dest;
759
 
760
  /* Now it is time to insert the first conditional expression
761
     into bi_call_bb and split this bb so that bi_call is
762
     shrink-wrapped.  */
763
  tn_cond_stmts = VEC_length (gimple, conds);
764
  cond_expr = NULL;
765
  cond_expr_start = VEC_index (gimple, conds, 0);
766
  for (ci = 0; ci < tn_cond_stmts; ci++)
767
    {
768
      gimple c = VEC_index (gimple, conds, ci);
769
      gcc_assert (c || ci != 0);
770
      if (!c)
771
        break;
772
      gsi_insert_before (&bi_call_bsi, c, GSI_SAME_STMT);
773
      cond_expr = c;
774
    }
775
  nconds--;
776
  ci++;
777
  gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND);
778
 
779
  /* Now the label.  */
780
  bi_call_label_decl = create_artificial_label (gimple_location (bi_call));
781
  bi_call_label = gimple_build_label (bi_call_label_decl);
782
  gsi_insert_before (&bi_call_bsi, bi_call_label, GSI_SAME_STMT);
783
 
784
  bi_call_in_edge0 = split_block (bi_call_bb, cond_expr);
785
  bi_call_in_edge0->flags &= ~EDGE_FALLTHRU;
786
  bi_call_in_edge0->flags |= EDGE_TRUE_VALUE;
787
  guard_bb0 = bi_call_bb;
788
  bi_call_bb = bi_call_in_edge0->dest;
789
  join_tgt_in_edge_fall_thru = make_edge (guard_bb0, join_tgt_bb,
790
                                          EDGE_FALSE_VALUE);
791
 
792
  bi_call_in_edge0->probability = REG_BR_PROB_BASE * ERR_PROB;
793
  join_tgt_in_edge_fall_thru->probability =
794
      REG_BR_PROB_BASE - bi_call_in_edge0->probability;
795
 
796
  /* Code generation for the rest of the conditions  */
797
  guard_bb = guard_bb0;
798
  while (nconds > 0)
799
    {
800
      unsigned ci0;
801
      edge bi_call_in_edge;
802
      gimple_stmt_iterator guard_bsi = gsi_for_stmt (cond_expr_start);
803
      ci0 = ci;
804
      cond_expr_start = VEC_index (gimple, conds, ci0);
805
      for (; ci < tn_cond_stmts; ci++)
806
        {
807
          gimple c = VEC_index (gimple, conds, ci);
808
          gcc_assert (c || ci != ci0);
809
          if (!c)
810
            break;
811
          gsi_insert_before (&guard_bsi, c, GSI_SAME_STMT);
812
          cond_expr = c;
813
        }
814
      nconds--;
815
      ci++;
816
      gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND);
817
      guard_bb_in_edge = split_block (guard_bb, cond_expr);
818
      guard_bb_in_edge->flags &= ~EDGE_FALLTHRU;
819
      guard_bb_in_edge->flags |= EDGE_FALSE_VALUE;
820
 
821
      bi_call_in_edge = make_edge (guard_bb, bi_call_bb, EDGE_TRUE_VALUE);
822
 
823
      bi_call_in_edge->probability = REG_BR_PROB_BASE * ERR_PROB;
824
      guard_bb_in_edge->probability =
825
          REG_BR_PROB_BASE - bi_call_in_edge->probability;
826
    }
827
 
828
  VEC_free (gimple, heap, conds);
829
  if (dump_file && (dump_flags & TDF_DETAILS))
830
    {
831
      location_t loc;
832
      loc = gimple_location (bi_call);
833
      fprintf (dump_file,
834
               "%s:%d: note: function call is shrink-wrapped"
835
               " into error conditions.\n",
836
               LOCATION_FILE (loc), LOCATION_LINE (loc));
837
    }
838
 
839
  return true;
840
}
841
 
842
/* The top level function for conditional dead code shrink
843
   wrapping transformation.  */
844
 
845
static bool
846
shrink_wrap_conditional_dead_built_in_calls (VEC (gimple, heap) *calls)
847
{
848
  bool changed = false;
849
  unsigned i = 0;
850
 
851
  unsigned n = VEC_length (gimple, calls);
852
  if (n == 0)
853
    return false;
854
 
855
  for (; i < n ; i++)
856
    {
857
      gimple bi_call = VEC_index (gimple, calls, i);
858
      changed |= shrink_wrap_one_built_in_call (bi_call);
859
    }
860
 
861
  return changed;
862
}
863
 
864
/* Pass entry points.  */
865
 
866
static unsigned int
867
tree_call_cdce (void)
868
{
869
  basic_block bb;
870
  gimple_stmt_iterator i;
871
  bool something_changed = false;
872
  VEC (gimple, heap) *cond_dead_built_in_calls = NULL;
873
  FOR_EACH_BB (bb)
874
    {
875
      /* Collect dead call candidates.  */
876
      for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
877
        {
878
          gimple stmt = gsi_stmt (i);
879
          if (is_gimple_call (stmt)
880
              && is_call_dce_candidate (stmt))
881
            {
882
              if (dump_file && (dump_flags & TDF_DETAILS))
883
                {
884
                  fprintf (dump_file, "Found conditional dead call: ");
885
                  print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
886
                  fprintf (dump_file, "\n");
887
                }
888
              if (cond_dead_built_in_calls == NULL)
889
                cond_dead_built_in_calls = VEC_alloc (gimple, heap, 64);
890
              VEC_safe_push (gimple, heap, cond_dead_built_in_calls, stmt);
891
            }
892
        }
893
    }
894
 
895
  if (cond_dead_built_in_calls == NULL)
896
    return 0;
897
 
898
  something_changed
899
    = shrink_wrap_conditional_dead_built_in_calls (cond_dead_built_in_calls);
900
 
901
  VEC_free (gimple, heap, cond_dead_built_in_calls);
902
 
903
  if (something_changed)
904
    {
905
      free_dominance_info (CDI_DOMINATORS);
906
      free_dominance_info (CDI_POST_DOMINATORS);
907
      /* As we introduced new control-flow we need to insert PHI-nodes
908
         for the call-clobbers of the remaining call.  */
909
      mark_sym_for_renaming (gimple_vop (cfun));
910
      return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect
911
              | TODO_remove_unused_locals);
912
    }
913
  else
914
    return 0;
915
}
916
 
917
static bool
918
gate_call_cdce (void)
919
{
920
  /* The limit constants used in the implementation
921
     assume IEEE floating point format.  Other formats
922
     can be supported in the future if needed.  */
923
  return flag_tree_builtin_call_dce != 0 && optimize_function_for_speed_p (cfun);
924
}
925
 
926
struct gimple_opt_pass pass_call_cdce =
927
{
928
 {
929
  GIMPLE_PASS,
930
  "cdce",                               /* name */
931
  gate_call_cdce,                       /* gate */
932
  tree_call_cdce,                       /* execute */
933
  NULL,                                 /* sub */
934
  NULL,                                 /* next */
935
  0,                                    /* static_pass_number */
936
  TV_TREE_CALL_CDCE,                    /* tv_id */
937
  PROP_cfg | PROP_ssa,                  /* properties_required */
938
  0,                                    /* properties_provided */
939
  0,                                    /* properties_destroyed */
940
  0,                                    /* todo_flags_start */
941
  TODO_dump_func | TODO_verify_ssa      /* todo_flags_finish */
942
 }
943
};

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