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c2699190 | 1 | /* Conditional Dead Call Elimination pass for the GNU compiler. |
cf835838 | 2 | Copyright (C) 2008, 2009, 2010 |
c2699190 XDL |
3 | Free Software Foundation, Inc. |
4 | Contributed by Xinliang David Li <davidxl@google.com> | |
5 | ||
6 | This file is part of GCC. | |
b8698a0f | 7 | |
c2699190 XDL |
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. | |
b8698a0f | 12 | |
c2699190 XDL |
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. | |
b8698a0f | 17 | |
c2699190 XDL |
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" | |
c2699190 | 26 | #include "basic-block.h" |
c2699190 | 27 | #include "tree.h" |
cf835838 | 28 | #include "gimple-pretty-print.h" |
c2699190 | 29 | #include "tree-flow.h" |
726a989a | 30 | #include "gimple.h" |
c2699190 XDL |
31 | #include "tree-dump.h" |
32 | #include "tree-pass.h" | |
33 | #include "timevar.h" | |
34 | #include "flags.h" | |
35 | \f | |
36 | ||
37 | /* Conditional dead call elimination | |
38 | ||
39 | Some builtin functions can set errno on error conditions, but they | |
40 | are otherwise pure. If the result of a call to such a function is | |
41 | not used, the compiler can still not eliminate the call without | |
42 | powerful interprocedural analysis to prove that the errno is not | |
43 | checked. However, if the conditions under which the error occurs | |
b8698a0f | 44 | are known, the compiler can conditionally dead code eliminate the |
c2699190 XDL |
45 | calls by shrink-wrapping the semi-dead calls into the error condition: |
46 | ||
47 | built_in_call (args) | |
48 | ==> | |
49 | if (error_cond (args)) | |
50 | built_in_call (args) | |
51 | ||
52 | An actual simple example is : | |
53 | log (x); // Mostly dead call | |
54 | ==> | |
55 | if (x < 0) | |
56 | log (x); | |
57 | With this change, call to log (x) is effectively eliminated, as | |
58 | in majority of the cases, log won't be called with x out of | |
59 | range. The branch is totally predictable, so the branch cost | |
b8698a0f | 60 | is low. |
c2699190 XDL |
61 | |
62 | Note that library functions are not supposed to clear errno to zero without | |
63 | error. See IEEE Std 1003.1, section 2.3 Error Numbers, and section 7.5:3 of | |
64 | ISO/IEC 9899 (C99). | |
65 | ||
66 | The condition wrapping the builtin call is conservatively set to avoid too | |
67 | aggressive (wrong) shrink wrapping. The optimization is called conditional | |
68 | dead call elimination because the call is eliminated under the condition | |
69 | that the input arguments would not lead to domain or range error (for | |
70 | instance when x <= 0 for a log (x) call), however the chances that the error | |
71 | condition is hit is very low (those builtin calls which are conditionally | |
72 | dead are usually part of the C++ abstraction penalty exposed after | |
73 | inlining). */ | |
74 | ||
75 | ||
b8698a0f | 76 | /* A structure for representing input domain of |
c2699190 | 77 | a function argument in integer. If the lower |
b8698a0f L |
78 | bound is -inf, has_lb is set to false. If the |
79 | upper bound is +inf, has_ub is false. | |
80 | is_lb_inclusive and is_ub_inclusive are flags | |
81 | to indicate if lb and ub value are inclusive | |
c2699190 XDL |
82 | respectively. */ |
83 | ||
84 | typedef struct input_domain | |
85 | { | |
86 | int lb; | |
87 | int ub; | |
88 | bool has_lb; | |
89 | bool has_ub; | |
90 | bool is_lb_inclusive; | |
91 | bool is_ub_inclusive; | |
92 | } inp_domain; | |
93 | ||
c2699190 | 94 | /* A helper function to construct and return an input |
b8698a0f | 95 | domain object. LB is the lower bound, HAS_LB is |
c2699190 XDL |
96 | a boolean flag indicating if the lower bound exists, |
97 | and LB_INCLUSIVE is a boolean flag indicating if the | |
98 | lower bound is inclusive or not. UB, HAS_UB, and | |
b8698a0f | 99 | UB_INCLUSIVE have the same meaning, but for upper |
c2699190 XDL |
100 | bound of the domain. */ |
101 | ||
102 | static inp_domain | |
103 | get_domain (int lb, bool has_lb, bool lb_inclusive, | |
104 | int ub, bool has_ub, bool ub_inclusive) | |
105 | { | |
106 | inp_domain domain; | |
107 | domain.lb = lb; | |
108 | domain.has_lb = has_lb; | |
109 | domain.is_lb_inclusive = lb_inclusive; | |
110 | domain.ub = ub; | |
111 | domain.has_ub = has_ub; | |
112 | domain.is_ub_inclusive = ub_inclusive; | |
113 | return domain; | |
114 | } | |
115 | ||
b8698a0f | 116 | /* A helper function to check the target format for the |
c2699190 | 117 | argument type. In this implementation, only IEEE formats |
b8698a0f | 118 | are supported. ARG is the call argument to be checked. |
c2699190 XDL |
119 | Returns true if the format is supported. To support other |
120 | target formats, function get_no_error_domain needs to be | |
b8698a0f L |
121 | enhanced to have range bounds properly computed. Since |
122 | the check is cheap (very small number of candidates | |
c2699190 XDL |
123 | to be checked), the result is not cached for each float type. */ |
124 | ||
125 | static bool | |
126 | check_target_format (tree arg) | |
127 | { | |
128 | tree type; | |
129 | enum machine_mode mode; | |
130 | const struct real_format *rfmt; | |
b8698a0f | 131 | |
c2699190 XDL |
132 | type = TREE_TYPE (arg); |
133 | mode = TYPE_MODE (type); | |
134 | rfmt = REAL_MODE_FORMAT (mode); | |
5d94a6d0 | 135 | if ((mode == SFmode |
ea8bce02 AS |
136 | && (rfmt == &ieee_single_format || rfmt == &mips_single_format |
137 | || rfmt == &motorola_single_format)) | |
5d94a6d0 | 138 | || (mode == DFmode |
ea8bce02 AS |
139 | && (rfmt == &ieee_double_format || rfmt == &mips_double_format |
140 | || rfmt == &motorola_double_format)) | |
c2699190 | 141 | /* For long double, we can not really check XFmode |
b8698a0f L |
142 | which is only defined on intel platforms. |
143 | Candidate pre-selection using builtin function | |
144 | code guarantees that we are checking formats | |
c2699190 | 145 | for long double modes: double, quad, and extended. */ |
b8698a0f | 146 | || (mode != SFmode && mode != DFmode |
c2699190 | 147 | && (rfmt == &ieee_quad_format |
5d94a6d0 | 148 | || rfmt == &mips_quad_format |
ea8bce02 | 149 | || rfmt == &ieee_extended_motorola_format |
b8698a0f L |
150 | || rfmt == &ieee_extended_intel_96_format |
151 | || rfmt == &ieee_extended_intel_128_format | |
c2699190 XDL |
152 | || rfmt == &ieee_extended_intel_96_round_53_format))) |
153 | return true; | |
154 | ||
155 | return false; | |
156 | } | |
157 | ||
158 | \f | |
159 | /* A helper function to help select calls to pow that are suitable for | |
160 | conditional DCE transformation. It looks for pow calls that can be | |
161 | guided with simple conditions. Such calls either have constant base | |
b8698a0f | 162 | values or base values converted from integers. Returns true if |
c2699190 XDL |
163 | the pow call POW_CALL is a candidate. */ |
164 | ||
165 | /* The maximum integer bit size for base argument of a pow call | |
166 | that is suitable for shrink-wrapping transformation. */ | |
167 | #define MAX_BASE_INT_BIT_SIZE 32 | |
168 | ||
169 | static bool | |
726a989a | 170 | check_pow (gimple pow_call) |
c2699190 XDL |
171 | { |
172 | tree base, expn; | |
173 | enum tree_code bc, ec; | |
174 | ||
726a989a | 175 | if (gimple_call_num_args (pow_call) != 2) |
c2699190 XDL |
176 | return false; |
177 | ||
726a989a RB |
178 | base = gimple_call_arg (pow_call, 0); |
179 | expn = gimple_call_arg (pow_call, 1); | |
c2699190 XDL |
180 | |
181 | if (!check_target_format (expn)) | |
182 | return false; | |
183 | ||
184 | bc = TREE_CODE (base); | |
185 | ec = TREE_CODE (expn); | |
186 | ||
187 | /* Folding candidates are not interesting. | |
188 | Can actually assert that it is already folded. */ | |
189 | if (ec == REAL_CST && bc == REAL_CST) | |
190 | return false; | |
191 | ||
192 | if (bc == REAL_CST) | |
193 | { | |
194 | /* Only handle a fixed range of constant. */ | |
195 | REAL_VALUE_TYPE mv; | |
196 | REAL_VALUE_TYPE bcv = TREE_REAL_CST (base); | |
197 | if (REAL_VALUES_EQUAL (bcv, dconst1)) | |
198 | return false; | |
199 | if (REAL_VALUES_LESS (bcv, dconst1)) | |
200 | return false; | |
201 | real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, 0, 1); | |
202 | if (REAL_VALUES_LESS (mv, bcv)) | |
203 | return false; | |
204 | return true; | |
205 | } | |
206 | else if (bc == SSA_NAME) | |
207 | { | |
726a989a RB |
208 | tree base_val0, base_var, type; |
209 | gimple base_def; | |
c2699190 XDL |
210 | int bit_sz; |
211 | ||
212 | /* Only handles cases where base value is converted | |
b8698a0f | 213 | from integer values. */ |
c2699190 | 214 | base_def = SSA_NAME_DEF_STMT (base); |
726a989a | 215 | if (gimple_code (base_def) != GIMPLE_ASSIGN) |
c2699190 XDL |
216 | return false; |
217 | ||
726a989a | 218 | if (gimple_assign_rhs_code (base_def) != FLOAT_EXPR) |
c2699190 | 219 | return false; |
726a989a | 220 | base_val0 = gimple_assign_rhs1 (base_def); |
c2699190 XDL |
221 | |
222 | base_var = SSA_NAME_VAR (base_val0); | |
223 | if (!DECL_P (base_var)) | |
224 | return false; | |
225 | ||
226 | type = TREE_TYPE (base_var); | |
227 | if (TREE_CODE (type) != INTEGER_TYPE) | |
228 | return false; | |
229 | bit_sz = TYPE_PRECISION (type); | |
230 | /* If the type of the base is too wide, | |
231 | the resulting shrink wrapping condition | |
232 | will be too conservative. */ | |
233 | if (bit_sz > MAX_BASE_INT_BIT_SIZE) | |
234 | return false; | |
235 | ||
236 | return true; | |
237 | } | |
238 | else | |
239 | return false; | |
240 | } | |
241 | ||
242 | /* A helper function to help select candidate function calls that are | |
243 | suitable for conditional DCE. Candidate functions must have single | |
244 | valid input domain in this implementation except for pow (see check_pow). | |
245 | Returns true if the function call is a candidate. */ | |
246 | ||
247 | static bool | |
726a989a | 248 | check_builtin_call (gimple bcall) |
c2699190 XDL |
249 | { |
250 | tree arg; | |
251 | ||
726a989a | 252 | arg = gimple_call_arg (bcall, 0); |
c2699190 XDL |
253 | return check_target_format (arg); |
254 | } | |
255 | ||
256 | /* A helper function to determine if a builtin function call is a | |
257 | candidate for conditional DCE. Returns true if the builtin call | |
258 | is a candidate. */ | |
259 | ||
260 | static bool | |
726a989a | 261 | is_call_dce_candidate (gimple call) |
c2699190 XDL |
262 | { |
263 | tree fn; | |
264 | enum built_in_function fnc; | |
265 | ||
726a989a RB |
266 | /* Only potentially dead calls are considered. */ |
267 | if (gimple_call_lhs (call)) | |
c2699190 XDL |
268 | return false; |
269 | ||
726a989a RB |
270 | fn = gimple_call_fndecl (call); |
271 | if (!fn | |
b8698a0f | 272 | || !DECL_BUILT_IN (fn) |
c2699190 XDL |
273 | || (DECL_BUILT_IN_CLASS (fn) != BUILT_IN_NORMAL)) |
274 | return false; | |
275 | ||
276 | fnc = DECL_FUNCTION_CODE (fn); | |
277 | switch (fnc) | |
278 | { | |
279 | /* Trig functions. */ | |
280 | CASE_FLT_FN (BUILT_IN_ACOS): | |
281 | CASE_FLT_FN (BUILT_IN_ASIN): | |
282 | /* Hyperbolic functions. */ | |
283 | CASE_FLT_FN (BUILT_IN_ACOSH): | |
284 | CASE_FLT_FN (BUILT_IN_ATANH): | |
285 | CASE_FLT_FN (BUILT_IN_COSH): | |
286 | CASE_FLT_FN (BUILT_IN_SINH): | |
287 | /* Log functions. */ | |
288 | CASE_FLT_FN (BUILT_IN_LOG): | |
289 | CASE_FLT_FN (BUILT_IN_LOG2): | |
290 | CASE_FLT_FN (BUILT_IN_LOG10): | |
291 | CASE_FLT_FN (BUILT_IN_LOG1P): | |
292 | /* Exp functions. */ | |
293 | CASE_FLT_FN (BUILT_IN_EXP): | |
294 | CASE_FLT_FN (BUILT_IN_EXP2): | |
295 | CASE_FLT_FN (BUILT_IN_EXP10): | |
296 | CASE_FLT_FN (BUILT_IN_EXPM1): | |
297 | CASE_FLT_FN (BUILT_IN_POW10): | |
298 | /* Sqrt. */ | |
299 | CASE_FLT_FN (BUILT_IN_SQRT): | |
300 | return check_builtin_call (call); | |
301 | /* Special one: two argument pow. */ | |
302 | case BUILT_IN_POW: | |
303 | return check_pow (call); | |
304 | default: | |
305 | break; | |
306 | } | |
307 | ||
308 | return false; | |
309 | } | |
310 | ||
311 | \f | |
312 | /* A helper function to generate gimple statements for | |
313 | one bound comparison. ARG is the call argument to | |
314 | be compared with the bound, LBUB is the bound value | |
315 | in integer, TCODE is the tree_code of the comparison, | |
316 | TEMP_NAME1/TEMP_NAME2 are names of the temporaries, | |
317 | CONDS is a vector holding the produced GIMPLE statements, | |
318 | and NCONDS points to the variable holding the number | |
b8698a0f | 319 | of logical comparisons. CONDS is either empty or |
c2699190 XDL |
320 | a list ended with a null tree. */ |
321 | ||
322 | static void | |
b8698a0f | 323 | gen_one_condition (tree arg, int lbub, |
c2699190 XDL |
324 | enum tree_code tcode, |
325 | const char *temp_name1, | |
726a989a RB |
326 | const char *temp_name2, |
327 | VEC (gimple, heap) *conds, | |
c2699190 XDL |
328 | unsigned *nconds) |
329 | { | |
330 | tree lbub_real_cst, lbub_cst, float_type; | |
331 | tree temp, tempn, tempc, tempcn; | |
726a989a | 332 | gimple stmt1, stmt2, stmt3; |
c2699190 XDL |
333 | |
334 | float_type = TREE_TYPE (arg); | |
335 | lbub_cst = build_int_cst (integer_type_node, lbub); | |
336 | lbub_real_cst = build_real_from_int_cst (float_type, lbub_cst); | |
337 | ||
338 | temp = create_tmp_var (float_type, temp_name1); | |
726a989a | 339 | stmt1 = gimple_build_assign (temp, arg); |
c2699190 | 340 | tempn = make_ssa_name (temp, stmt1); |
726a989a | 341 | gimple_assign_set_lhs (stmt1, tempn); |
c2699190 XDL |
342 | |
343 | tempc = create_tmp_var (boolean_type_node, temp_name2); | |
726a989a RB |
344 | stmt2 = gimple_build_assign (tempc, |
345 | fold_build2 (tcode, | |
346 | boolean_type_node, | |
347 | tempn, lbub_real_cst)); | |
c2699190 | 348 | tempcn = make_ssa_name (tempc, stmt2); |
726a989a RB |
349 | gimple_assign_set_lhs (stmt2, tempcn); |
350 | ||
351 | stmt3 = gimple_build_cond_from_tree (tempcn, NULL_TREE, NULL_TREE); | |
352 | VEC_quick_push (gimple, conds, stmt1); | |
353 | VEC_quick_push (gimple, conds, stmt2); | |
354 | VEC_quick_push (gimple, conds, stmt3); | |
c2699190 XDL |
355 | (*nconds)++; |
356 | } | |
357 | ||
358 | /* A helper function to generate GIMPLE statements for | |
359 | out of input domain check. ARG is the call argument | |
360 | to be runtime checked, DOMAIN holds the valid domain | |
361 | for the given function, CONDS points to the vector | |
b8698a0f L |
362 | holding the result GIMPLE statements. *NCONDS is |
363 | the number of logical comparisons. This function | |
c2699190 XDL |
364 | produces no more than two logical comparisons, one |
365 | for lower bound check, one for upper bound check. */ | |
366 | ||
367 | static void | |
368 | gen_conditions_for_domain (tree arg, inp_domain domain, | |
b8698a0f | 369 | VEC (gimple, heap) *conds, |
c2699190 XDL |
370 | unsigned *nconds) |
371 | { | |
372 | if (domain.has_lb) | |
373 | gen_one_condition (arg, domain.lb, | |
374 | (domain.is_lb_inclusive | |
375 | ? LT_EXPR : LE_EXPR), | |
376 | "DCE_COND_LB", "DCE_COND_LB_TEST", | |
377 | conds, nconds); | |
378 | ||
379 | if (domain.has_ub) | |
380 | { | |
381 | /* Now push a separator. */ | |
382 | if (domain.has_lb) | |
726a989a | 383 | VEC_quick_push (gimple, conds, NULL); |
c2699190 XDL |
384 | |
385 | gen_one_condition (arg, domain.ub, | |
386 | (domain.is_ub_inclusive | |
387 | ? GT_EXPR : GE_EXPR), | |
388 | "DCE_COND_UB", "DCE_COND_UB_TEST", | |
389 | conds, nconds); | |
390 | } | |
391 | } | |
392 | ||
393 | ||
394 | /* A helper function to generate condition | |
395 | code for the y argument in call pow (some_const, y). | |
b8698a0f | 396 | See candidate selection in check_pow. Since the |
c2699190 XDL |
397 | candidates' base values have a limited range, |
398 | the guarded code generated for y are simple: | |
399 | if (y > max_y) | |
400 | pow (const, y); | |
401 | Note max_y can be computed separately for each | |
402 | const base, but in this implementation, we | |
403 | choose to compute it using the max base | |
404 | in the allowed range for the purpose of | |
405 | simplicity. BASE is the constant base value, | |
406 | EXPN is the expression for the exponent argument, | |
407 | *CONDS is the vector to hold resulting statements, | |
408 | and *NCONDS is the number of logical conditions. */ | |
409 | ||
410 | static void | |
411 | gen_conditions_for_pow_cst_base (tree base, tree expn, | |
726a989a | 412 | VEC (gimple, heap) *conds, |
c2699190 XDL |
413 | unsigned *nconds) |
414 | { | |
b8698a0f L |
415 | inp_domain exp_domain; |
416 | /* Validate the range of the base constant to make | |
c2699190 XDL |
417 | sure it is consistent with check_pow. */ |
418 | REAL_VALUE_TYPE mv; | |
419 | REAL_VALUE_TYPE bcv = TREE_REAL_CST (base); | |
420 | gcc_assert (!REAL_VALUES_EQUAL (bcv, dconst1) | |
421 | && !REAL_VALUES_LESS (bcv, dconst1)); | |
422 | real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, 0, 1); | |
423 | gcc_assert (!REAL_VALUES_LESS (mv, bcv)); | |
424 | ||
425 | exp_domain = get_domain (0, false, false, | |
426 | 127, true, false); | |
427 | ||
428 | gen_conditions_for_domain (expn, exp_domain, | |
429 | conds, nconds); | |
430 | } | |
431 | ||
432 | /* Generate error condition code for pow calls with | |
433 | non constant base values. The candidates selected | |
434 | have their base argument value converted from | |
435 | integer (see check_pow) value (1, 2, 4 bytes), and | |
436 | the max exp value is computed based on the size | |
437 | of the integer type (i.e. max possible base value). | |
438 | The resulting input domain for exp argument is thus | |
b8698a0f L |
439 | conservative (smaller than the max value allowed by |
440 | the runtime value of the base). BASE is the integer | |
441 | base value, EXPN is the expression for the exponent | |
442 | argument, *CONDS is the vector to hold resulting | |
443 | statements, and *NCONDS is the number of logical | |
c2699190 XDL |
444 | conditions. */ |
445 | ||
446 | static void | |
447 | gen_conditions_for_pow_int_base (tree base, tree expn, | |
726a989a | 448 | VEC (gimple, heap) *conds, |
c2699190 XDL |
449 | unsigned *nconds) |
450 | { | |
726a989a | 451 | gimple base_def; |
0f900dfa | 452 | tree base_val0; |
c2699190 XDL |
453 | tree base_var, int_type; |
454 | tree temp, tempn; | |
726a989a RB |
455 | tree cst0; |
456 | gimple stmt1, stmt2; | |
c2699190 XDL |
457 | int bit_sz, max_exp; |
458 | inp_domain exp_domain; | |
459 | ||
460 | base_def = SSA_NAME_DEF_STMT (base); | |
726a989a | 461 | base_val0 = gimple_assign_rhs1 (base_def); |
c2699190 XDL |
462 | base_var = SSA_NAME_VAR (base_val0); |
463 | int_type = TREE_TYPE (base_var); | |
464 | bit_sz = TYPE_PRECISION (int_type); | |
b8698a0f | 465 | gcc_assert (bit_sz > 0 |
c2699190 XDL |
466 | && bit_sz <= MAX_BASE_INT_BIT_SIZE); |
467 | ||
468 | /* Determine the max exp argument value according to | |
469 | the size of the base integer. The max exp value | |
470 | is conservatively estimated assuming IEEE754 double | |
471 | precision format. */ | |
472 | if (bit_sz == 8) | |
473 | max_exp = 128; | |
474 | else if (bit_sz == 16) | |
475 | max_exp = 64; | |
476 | else | |
0f900dfa JJ |
477 | { |
478 | gcc_assert (bit_sz == MAX_BASE_INT_BIT_SIZE); | |
479 | max_exp = 32; | |
480 | } | |
c2699190 XDL |
481 | |
482 | /* For pow ((double)x, y), generate the following conditions: | |
483 | cond 1: | |
484 | temp1 = x; | |
485 | if (temp1 <= 0) | |
486 | ||
487 | cond 2: | |
488 | temp2 = y; | |
489 | if (temp2 > max_exp_real_cst) */ | |
490 | ||
491 | /* Generate condition in reverse order -- first | |
492 | the condition for the exp argument. */ | |
493 | ||
494 | exp_domain = get_domain (0, false, false, | |
495 | max_exp, true, true); | |
496 | ||
497 | gen_conditions_for_domain (expn, exp_domain, | |
498 | conds, nconds); | |
499 | ||
500 | /* Now generate condition for the base argument. | |
501 | Note it does not use the helper function | |
502 | gen_conditions_for_domain because the base | |
503 | type is integer. */ | |
504 | ||
505 | /* Push a separator. */ | |
726a989a | 506 | VEC_quick_push (gimple, conds, NULL); |
c2699190 XDL |
507 | |
508 | temp = create_tmp_var (int_type, "DCE_COND1"); | |
509 | cst0 = build_int_cst (int_type, 0); | |
726a989a | 510 | stmt1 = gimple_build_assign (temp, base_val0); |
c2699190 | 511 | tempn = make_ssa_name (temp, stmt1); |
726a989a RB |
512 | gimple_assign_set_lhs (stmt1, tempn); |
513 | stmt2 = gimple_build_cond (LE_EXPR, tempn, cst0, NULL_TREE, NULL_TREE); | |
c2699190 | 514 | |
726a989a RB |
515 | VEC_quick_push (gimple, conds, stmt1); |
516 | VEC_quick_push (gimple, conds, stmt2); | |
c2699190 XDL |
517 | (*nconds)++; |
518 | } | |
519 | ||
520 | /* Method to generate conditional statements for guarding conditionally | |
521 | dead calls to pow. One or more statements can be generated for | |
522 | each logical condition. Statement groups of different conditions | |
523 | are separated by a NULL tree and they are stored in the VEC | |
524 | conds. The number of logical conditions are stored in *nconds. | |
525 | ||
526 | See C99 standard, 7.12.7.4:2, for description of pow (x, y). | |
527 | The precise condition for domain errors are complex. In this | |
528 | implementation, a simplified (but conservative) valid domain | |
529 | for x and y are used: x is positive to avoid dom errors, while | |
530 | y is smaller than a upper bound (depending on x) to avoid range | |
531 | errors. Runtime code is generated to check x (if not constant) | |
532 | and y against the valid domain. If it is out, jump to the call, | |
533 | otherwise the call is bypassed. POW_CALL is the call statement, | |
534 | *CONDS is a vector holding the resulting condition statements, | |
535 | and *NCONDS is the number of logical conditions. */ | |
536 | ||
537 | static void | |
b8698a0f | 538 | gen_conditions_for_pow (gimple pow_call, VEC (gimple, heap) *conds, |
c2699190 XDL |
539 | unsigned *nconds) |
540 | { | |
541 | tree base, expn; | |
0f900dfa | 542 | enum tree_code bc; |
c2699190 XDL |
543 | |
544 | #ifdef ENABLE_CHECKING | |
545 | gcc_assert (check_pow (pow_call)); | |
546 | #endif | |
547 | ||
548 | *nconds = 0; | |
549 | ||
726a989a RB |
550 | base = gimple_call_arg (pow_call, 0); |
551 | expn = gimple_call_arg (pow_call, 1); | |
c2699190 XDL |
552 | |
553 | bc = TREE_CODE (base); | |
c2699190 XDL |
554 | |
555 | if (bc == REAL_CST) | |
0f900dfa | 556 | gen_conditions_for_pow_cst_base (base, expn, conds, nconds); |
c2699190 | 557 | else if (bc == SSA_NAME) |
0f900dfa | 558 | gen_conditions_for_pow_int_base (base, expn, conds, nconds); |
c2699190 XDL |
559 | else |
560 | gcc_unreachable (); | |
561 | } | |
562 | ||
563 | /* A helper routine to help computing the valid input domain | |
564 | for a builtin function. See C99 7.12.7 for details. In this | |
565 | implementation, we only handle single region domain. The | |
566 | resulting region can be conservative (smaller) than the actual | |
567 | one and rounded to integers. Some of the bounds are documented | |
568 | in the standard, while other limit constants are computed | |
b8698a0f L |
569 | assuming IEEE floating point format (for SF and DF modes). |
570 | Since IEEE only sets minimum requirements for long double format, | |
571 | different long double formats exist under different implementations | |
572 | (e.g, 64 bit double precision (DF), 80 bit double-extended | |
573 | precision (XF), and 128 bit quad precision (QF) ). For simplicity, | |
574 | in this implementation, the computed bounds for long double assume | |
575 | 64 bit format (DF), and are therefore conservative. Another | |
c2699190 | 576 | assumption is that single precision float type is always SF mode, |
b8698a0f | 577 | and double type is DF mode. This function is quite |
c2699190 XDL |
578 | implementation specific, so it may not be suitable to be part of |
579 | builtins.c. This needs to be revisited later to see if it can | |
580 | be leveraged in x87 assembly expansion. */ | |
581 | ||
582 | static inp_domain | |
583 | get_no_error_domain (enum built_in_function fnc) | |
584 | { | |
585 | switch (fnc) | |
586 | { | |
587 | /* Trig functions: return [-1, +1] */ | |
588 | CASE_FLT_FN (BUILT_IN_ACOS): | |
589 | CASE_FLT_FN (BUILT_IN_ASIN): | |
590 | return get_domain (-1, true, true, | |
591 | 1, true, true); | |
592 | /* Hyperbolic functions. */ | |
593 | CASE_FLT_FN (BUILT_IN_ACOSH): | |
594 | /* acosh: [1, +inf) */ | |
595 | return get_domain (1, true, true, | |
596 | 1, false, false); | |
597 | CASE_FLT_FN (BUILT_IN_ATANH): | |
598 | /* atanh: (-1, +1) */ | |
599 | return get_domain (-1, true, false, | |
600 | 1, true, false); | |
601 | case BUILT_IN_COSHF: | |
602 | case BUILT_IN_SINHF: | |
603 | /* coshf: (-89, +89) */ | |
604 | return get_domain (-89, true, false, | |
605 | 89, true, false); | |
606 | case BUILT_IN_COSH: | |
607 | case BUILT_IN_SINH: | |
608 | case BUILT_IN_COSHL: | |
609 | case BUILT_IN_SINHL: | |
610 | /* cosh: (-710, +710) */ | |
611 | return get_domain (-710, true, false, | |
612 | 710, true, false); | |
613 | /* Log functions: (0, +inf) */ | |
614 | CASE_FLT_FN (BUILT_IN_LOG): | |
615 | CASE_FLT_FN (BUILT_IN_LOG2): | |
616 | CASE_FLT_FN (BUILT_IN_LOG10): | |
617 | return get_domain (0, true, false, | |
618 | 0, false, false); | |
619 | CASE_FLT_FN (BUILT_IN_LOG1P): | |
620 | return get_domain (-1, true, false, | |
621 | 0, false, false); | |
622 | /* Exp functions. */ | |
623 | case BUILT_IN_EXPF: | |
624 | case BUILT_IN_EXPM1F: | |
625 | /* expf: (-inf, 88) */ | |
626 | return get_domain (-1, false, false, | |
627 | 88, true, false); | |
628 | case BUILT_IN_EXP: | |
629 | case BUILT_IN_EXPM1: | |
630 | case BUILT_IN_EXPL: | |
631 | case BUILT_IN_EXPM1L: | |
632 | /* exp: (-inf, 709) */ | |
633 | return get_domain (-1, false, false, | |
634 | 709, true, false); | |
635 | case BUILT_IN_EXP2F: | |
636 | /* exp2f: (-inf, 128) */ | |
637 | return get_domain (-1, false, false, | |
638 | 128, true, false); | |
639 | case BUILT_IN_EXP2: | |
640 | case BUILT_IN_EXP2L: | |
641 | /* exp2: (-inf, 1024) */ | |
642 | return get_domain (-1, false, false, | |
643 | 1024, true, false); | |
644 | case BUILT_IN_EXP10F: | |
645 | case BUILT_IN_POW10F: | |
646 | /* exp10f: (-inf, 38) */ | |
647 | return get_domain (-1, false, false, | |
648 | 38, true, false); | |
649 | case BUILT_IN_EXP10: | |
650 | case BUILT_IN_POW10: | |
651 | case BUILT_IN_EXP10L: | |
652 | case BUILT_IN_POW10L: | |
653 | /* exp10: (-inf, 308) */ | |
654 | return get_domain (-1, false, false, | |
655 | 308, true, false); | |
656 | /* sqrt: [0, +inf) */ | |
657 | CASE_FLT_FN (BUILT_IN_SQRT): | |
658 | return get_domain (0, true, true, | |
659 | 0, false, false); | |
660 | default: | |
b8698a0f | 661 | gcc_unreachable (); |
c2699190 XDL |
662 | } |
663 | ||
b8698a0f | 664 | gcc_unreachable (); |
c2699190 XDL |
665 | } |
666 | ||
667 | /* The function to generate shrink wrap conditions for a partially | |
668 | dead builtin call whose return value is not used anywhere, | |
669 | but has to be kept live due to potential error condition. | |
b8698a0f L |
670 | BI_CALL is the builtin call, CONDS is the vector of statements |
671 | for condition code, NCODES is the pointer to the number of | |
c2699190 XDL |
672 | logical conditions. Statements belonging to different logical |
673 | condition are separated by NULL tree in the vector. */ | |
674 | ||
675 | static void | |
b8698a0f | 676 | gen_shrink_wrap_conditions (gimple bi_call, VEC (gimple, heap) *conds, |
c2699190 XDL |
677 | unsigned int *nconds) |
678 | { | |
726a989a RB |
679 | gimple call; |
680 | tree fn; | |
c2699190 XDL |
681 | enum built_in_function fnc; |
682 | ||
683 | gcc_assert (nconds && conds); | |
726a989a RB |
684 | gcc_assert (VEC_length (gimple, conds) == 0); |
685 | gcc_assert (is_gimple_call (bi_call)); | |
c2699190 XDL |
686 | |
687 | call = bi_call; | |
726a989a | 688 | fn = gimple_call_fndecl (call); |
c2699190 XDL |
689 | gcc_assert (fn && DECL_BUILT_IN (fn)); |
690 | fnc = DECL_FUNCTION_CODE (fn); | |
691 | *nconds = 0; | |
692 | ||
693 | if (fnc == BUILT_IN_POW) | |
694 | gen_conditions_for_pow (call, conds, nconds); | |
695 | else | |
696 | { | |
697 | tree arg; | |
698 | inp_domain domain = get_no_error_domain (fnc); | |
699 | *nconds = 0; | |
726a989a | 700 | arg = gimple_call_arg (bi_call, 0); |
c2699190 XDL |
701 | gen_conditions_for_domain (arg, domain, conds, nconds); |
702 | } | |
703 | ||
704 | return; | |
705 | } | |
706 | ||
707 | ||
708 | /* Probability of the branch (to the call) is taken. */ | |
709 | #define ERR_PROB 0.01 | |
710 | ||
b8698a0f L |
711 | /* The function to shrink wrap a partially dead builtin call |
712 | whose return value is not used anywhere, but has to be kept | |
c2699190 XDL |
713 | live due to potential error condition. Returns true if the |
714 | transformation actually happens. */ | |
715 | ||
b8698a0f | 716 | static bool |
726a989a | 717 | shrink_wrap_one_built_in_call (gimple bi_call) |
c2699190 | 718 | { |
726a989a | 719 | gimple_stmt_iterator bi_call_bsi; |
c2699190 XDL |
720 | basic_block bi_call_bb, join_tgt_bb, guard_bb, guard_bb0; |
721 | edge join_tgt_in_edge_from_call, join_tgt_in_edge_fall_thru; | |
722 | edge bi_call_in_edge0, guard_bb_in_edge; | |
726a989a | 723 | VEC (gimple, heap) *conds; |
c2699190 XDL |
724 | unsigned tn_cond_stmts, nconds; |
725 | unsigned ci; | |
726a989a RB |
726 | gimple cond_expr = NULL; |
727 | gimple cond_expr_start; | |
c2699190 | 728 | tree bi_call_label_decl; |
726a989a | 729 | gimple bi_call_label; |
c2699190 | 730 | |
726a989a | 731 | conds = VEC_alloc (gimple, heap, 12); |
c2699190 XDL |
732 | gen_shrink_wrap_conditions (bi_call, conds, &nconds); |
733 | ||
734 | /* This can happen if the condition generator decides | |
735 | it is not beneficial to do the transformation. Just | |
b8698a0f | 736 | return false and do not do any transformation for |
c2699190 XDL |
737 | the call. */ |
738 | if (nconds == 0) | |
739 | return false; | |
740 | ||
726a989a | 741 | bi_call_bb = gimple_bb (bi_call); |
c2699190 XDL |
742 | |
743 | /* Now find the join target bb -- split | |
744 | bi_call_bb if needed. */ | |
726a989a | 745 | bi_call_bsi = gsi_for_stmt (bi_call); |
c2699190 XDL |
746 | |
747 | join_tgt_in_edge_from_call = split_block (bi_call_bb, bi_call); | |
726a989a | 748 | bi_call_bsi = gsi_for_stmt (bi_call); |
c2699190 XDL |
749 | |
750 | join_tgt_bb = join_tgt_in_edge_from_call->dest; | |
751 | ||
752 | /* Now it is time to insert the first conditional expression | |
753 | into bi_call_bb and split this bb so that bi_call is | |
754 | shrink-wrapped. */ | |
726a989a | 755 | tn_cond_stmts = VEC_length (gimple, conds); |
c2699190 | 756 | cond_expr = NULL; |
726a989a | 757 | cond_expr_start = VEC_index (gimple, conds, 0); |
c2699190 XDL |
758 | for (ci = 0; ci < tn_cond_stmts; ci++) |
759 | { | |
726a989a | 760 | gimple c = VEC_index (gimple, conds, ci); |
c2699190 XDL |
761 | gcc_assert (c || ci != 0); |
762 | if (!c) | |
763 | break; | |
726a989a | 764 | gsi_insert_before (&bi_call_bsi, c, GSI_SAME_STMT); |
c2699190 XDL |
765 | cond_expr = c; |
766 | } | |
767 | nconds--; | |
768 | ci++; | |
726a989a | 769 | gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND); |
c2699190 XDL |
770 | |
771 | /* Now the label. */ | |
c2255bc4 | 772 | bi_call_label_decl = create_artificial_label (gimple_location (bi_call)); |
726a989a RB |
773 | bi_call_label = gimple_build_label (bi_call_label_decl); |
774 | gsi_insert_before (&bi_call_bsi, bi_call_label, GSI_SAME_STMT); | |
c2699190 XDL |
775 | |
776 | bi_call_in_edge0 = split_block (bi_call_bb, cond_expr); | |
777 | bi_call_in_edge0->flags &= ~EDGE_FALLTHRU; | |
778 | bi_call_in_edge0->flags |= EDGE_TRUE_VALUE; | |
779 | guard_bb0 = bi_call_bb; | |
780 | bi_call_bb = bi_call_in_edge0->dest; | |
b8698a0f | 781 | join_tgt_in_edge_fall_thru = make_edge (guard_bb0, join_tgt_bb, |
c2699190 XDL |
782 | EDGE_FALSE_VALUE); |
783 | ||
784 | bi_call_in_edge0->probability = REG_BR_PROB_BASE * ERR_PROB; | |
785 | join_tgt_in_edge_fall_thru->probability = | |
786 | REG_BR_PROB_BASE - bi_call_in_edge0->probability; | |
787 | ||
788 | /* Code generation for the rest of the conditions */ | |
789 | guard_bb = guard_bb0; | |
790 | while (nconds > 0) | |
791 | { | |
792 | unsigned ci0; | |
793 | edge bi_call_in_edge; | |
726a989a | 794 | gimple_stmt_iterator guard_bsi = gsi_for_stmt (cond_expr_start); |
c2699190 | 795 | ci0 = ci; |
726a989a | 796 | cond_expr_start = VEC_index (gimple, conds, ci0); |
c2699190 XDL |
797 | for (; ci < tn_cond_stmts; ci++) |
798 | { | |
726a989a | 799 | gimple c = VEC_index (gimple, conds, ci); |
c2699190 XDL |
800 | gcc_assert (c || ci != ci0); |
801 | if (!c) | |
802 | break; | |
726a989a | 803 | gsi_insert_before (&guard_bsi, c, GSI_SAME_STMT); |
c2699190 XDL |
804 | cond_expr = c; |
805 | } | |
806 | nconds--; | |
807 | ci++; | |
726a989a | 808 | gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND); |
c2699190 XDL |
809 | guard_bb_in_edge = split_block (guard_bb, cond_expr); |
810 | guard_bb_in_edge->flags &= ~EDGE_FALLTHRU; | |
811 | guard_bb_in_edge->flags |= EDGE_FALSE_VALUE; | |
812 | ||
813 | bi_call_in_edge = make_edge (guard_bb, bi_call_bb, EDGE_TRUE_VALUE); | |
814 | ||
815 | bi_call_in_edge->probability = REG_BR_PROB_BASE * ERR_PROB; | |
816 | guard_bb_in_edge->probability = | |
817 | REG_BR_PROB_BASE - bi_call_in_edge->probability; | |
818 | } | |
819 | ||
726a989a | 820 | VEC_free (gimple, heap, conds); |
c2699190 XDL |
821 | if (dump_file && (dump_flags & TDF_DETAILS)) |
822 | { | |
823 | location_t loc; | |
726a989a | 824 | loc = gimple_location (bi_call); |
c2699190 XDL |
825 | fprintf (dump_file, |
826 | "%s:%d: note: function call is shrink-wrapped" | |
827 | " into error conditions.\n", | |
828 | LOCATION_FILE (loc), LOCATION_LINE (loc)); | |
829 | } | |
830 | ||
831 | return true; | |
832 | } | |
833 | ||
834 | /* The top level function for conditional dead code shrink | |
835 | wrapping transformation. */ | |
836 | ||
837 | static bool | |
6b672a29 | 838 | shrink_wrap_conditional_dead_built_in_calls (VEC (gimple, heap) *calls) |
c2699190 XDL |
839 | { |
840 | bool changed = false; | |
841 | unsigned i = 0; | |
842 | ||
6b672a29 | 843 | unsigned n = VEC_length (gimple, calls); |
b8698a0f | 844 | if (n == 0) |
c2699190 XDL |
845 | return false; |
846 | ||
847 | for (; i < n ; i++) | |
848 | { | |
6b672a29 | 849 | gimple bi_call = VEC_index (gimple, calls, i); |
c2699190 XDL |
850 | changed |= shrink_wrap_one_built_in_call (bi_call); |
851 | } | |
852 | ||
853 | return changed; | |
854 | } | |
855 | ||
856 | /* Pass entry points. */ | |
857 | ||
858 | static unsigned int | |
859 | tree_call_cdce (void) | |
860 | { | |
861 | basic_block bb; | |
726a989a | 862 | gimple_stmt_iterator i; |
c2699190 | 863 | bool something_changed = false; |
6b672a29 | 864 | VEC (gimple, heap) *cond_dead_built_in_calls = NULL; |
c2699190 XDL |
865 | FOR_EACH_BB (bb) |
866 | { | |
867 | /* Collect dead call candidates. */ | |
726a989a | 868 | for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i)) |
c2699190 | 869 | { |
726a989a RB |
870 | gimple stmt = gsi_stmt (i); |
871 | if (is_gimple_call (stmt) | |
c2699190 XDL |
872 | && is_call_dce_candidate (stmt)) |
873 | { | |
874 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
875 | { | |
876 | fprintf (dump_file, "Found conditional dead call: "); | |
726a989a | 877 | print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
c2699190 XDL |
878 | fprintf (dump_file, "\n"); |
879 | } | |
6b672a29 JJ |
880 | if (cond_dead_built_in_calls == NULL) |
881 | cond_dead_built_in_calls = VEC_alloc (gimple, heap, 64); | |
882 | VEC_safe_push (gimple, heap, cond_dead_built_in_calls, stmt); | |
c2699190 XDL |
883 | } |
884 | } | |
885 | } | |
886 | ||
6b672a29 JJ |
887 | if (cond_dead_built_in_calls == NULL) |
888 | return 0; | |
889 | ||
890 | something_changed | |
891 | = shrink_wrap_conditional_dead_built_in_calls (cond_dead_built_in_calls); | |
c2699190 | 892 | |
726a989a | 893 | VEC_free (gimple, heap, cond_dead_built_in_calls); |
c2699190 XDL |
894 | |
895 | if (something_changed) | |
896 | { | |
897 | free_dominance_info (CDI_DOMINATORS); | |
898 | free_dominance_info (CDI_POST_DOMINATORS); | |
5006671f RG |
899 | /* As we introduced new control-flow we need to insert PHI-nodes |
900 | for the call-clobbers of the remaining call. */ | |
901 | mark_sym_for_renaming (gimple_vop (cfun)); | |
b8698a0f | 902 | return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect |
c2699190 XDL |
903 | | TODO_remove_unused_locals); |
904 | } | |
905 | else | |
906 | return 0; | |
907 | } | |
908 | ||
909 | static bool | |
910 | gate_call_cdce (void) | |
911 | { | |
912 | /* The limit constants used in the implementation | |
913 | assume IEEE floating point format. Other formats | |
914 | can be supported in the future if needed. */ | |
b8698a0f | 915 | return flag_tree_builtin_call_dce != 0 && optimize_function_for_speed_p (cfun); |
c2699190 XDL |
916 | } |
917 | ||
918 | struct gimple_opt_pass pass_call_cdce = | |
919 | { | |
920 | { | |
921 | GIMPLE_PASS, | |
922 | "cdce", /* name */ | |
923 | gate_call_cdce, /* gate */ | |
924 | tree_call_cdce, /* execute */ | |
925 | NULL, /* sub */ | |
926 | NULL, /* next */ | |
927 | 0, /* static_pass_number */ | |
928 | TV_TREE_CALL_CDCE, /* tv_id */ | |
929 | PROP_cfg | PROP_ssa, /* properties_required */ | |
930 | 0, /* properties_provided */ | |
931 | 0, /* properties_destroyed */ | |
932 | 0, /* todo_flags_start */ | |
933 | TODO_dump_func | TODO_verify_ssa /* todo_flags_finish */ | |
934 | } | |
935 | }; |