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c2699190 | 1 | /* Conditional Dead Call Elimination pass for the GNU compiler. |
23a5b65a | 2 | Copyright (C) 2008-2014 Free Software Foundation, Inc. |
c2699190 XDL |
3 | Contributed by Xinliang David Li <davidxl@google.com> |
4 | ||
5 | This file is part of GCC. | |
b8698a0f | 6 | |
c2699190 XDL |
7 | GCC is free software; you can redistribute it and/or modify it |
8 | under the terms of the GNU General Public License as published by the | |
9 | Free Software Foundation; either version 3, or (at your option) any | |
10 | later version. | |
b8698a0f | 11 | |
c2699190 XDL |
12 | GCC is distributed in the hope that it will be useful, but WITHOUT |
13 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
b8698a0f | 16 | |
c2699190 XDL |
17 | You should have received a copy of the GNU General Public License |
18 | along with GCC; see the file COPYING3. If not see | |
19 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
24 | #include "tm.h" | |
c2699190 | 25 | #include "basic-block.h" |
c2699190 | 26 | #include "tree.h" |
d8a2d370 | 27 | #include "stor-layout.h" |
cf835838 | 28 | #include "gimple-pretty-print.h" |
2fb9a547 AM |
29 | #include "tree-ssa-alias.h" |
30 | #include "internal-fn.h" | |
31 | #include "gimple-expr.h" | |
32 | #include "is-a.h" | |
726a989a | 33 | #include "gimple.h" |
5be5c238 | 34 | #include "gimple-iterator.h" |
442b4905 AM |
35 | #include "gimple-ssa.h" |
36 | #include "tree-cfg.h" | |
d8a2d370 | 37 | #include "stringpool.h" |
442b4905 AM |
38 | #include "tree-ssanames.h" |
39 | #include "tree-into-ssa.h" | |
c2699190 | 40 | #include "tree-pass.h" |
c2699190 XDL |
41 | #include "flags.h" |
42 | \f | |
43 | ||
44 | /* Conditional dead call elimination | |
45 | ||
46 | Some builtin functions can set errno on error conditions, but they | |
47 | are otherwise pure. If the result of a call to such a function is | |
48 | not used, the compiler can still not eliminate the call without | |
49 | powerful interprocedural analysis to prove that the errno is not | |
50 | checked. However, if the conditions under which the error occurs | |
b8698a0f | 51 | are known, the compiler can conditionally dead code eliminate the |
c2699190 XDL |
52 | calls by shrink-wrapping the semi-dead calls into the error condition: |
53 | ||
54 | built_in_call (args) | |
55 | ==> | |
56 | if (error_cond (args)) | |
57 | built_in_call (args) | |
58 | ||
59 | An actual simple example is : | |
60 | log (x); // Mostly dead call | |
61 | ==> | |
62 | if (x < 0) | |
63 | log (x); | |
64 | With this change, call to log (x) is effectively eliminated, as | |
65 | in majority of the cases, log won't be called with x out of | |
66 | range. The branch is totally predictable, so the branch cost | |
b8698a0f | 67 | is low. |
c2699190 XDL |
68 | |
69 | Note that library functions are not supposed to clear errno to zero without | |
70 | error. See IEEE Std 1003.1, section 2.3 Error Numbers, and section 7.5:3 of | |
71 | ISO/IEC 9899 (C99). | |
72 | ||
73 | The condition wrapping the builtin call is conservatively set to avoid too | |
74 | aggressive (wrong) shrink wrapping. The optimization is called conditional | |
75 | dead call elimination because the call is eliminated under the condition | |
76 | that the input arguments would not lead to domain or range error (for | |
77 | instance when x <= 0 for a log (x) call), however the chances that the error | |
78 | condition is hit is very low (those builtin calls which are conditionally | |
79 | dead are usually part of the C++ abstraction penalty exposed after | |
80 | inlining). */ | |
81 | ||
82 | ||
b8698a0f | 83 | /* A structure for representing input domain of |
c2699190 | 84 | a function argument in integer. If the lower |
b8698a0f L |
85 | bound is -inf, has_lb is set to false. If the |
86 | upper bound is +inf, has_ub is false. | |
87 | is_lb_inclusive and is_ub_inclusive are flags | |
88 | to indicate if lb and ub value are inclusive | |
c2699190 XDL |
89 | respectively. */ |
90 | ||
91 | typedef struct input_domain | |
92 | { | |
93 | int lb; | |
94 | int ub; | |
95 | bool has_lb; | |
96 | bool has_ub; | |
97 | bool is_lb_inclusive; | |
98 | bool is_ub_inclusive; | |
99 | } inp_domain; | |
100 | ||
c2699190 | 101 | /* A helper function to construct and return an input |
b8698a0f | 102 | domain object. LB is the lower bound, HAS_LB is |
c2699190 XDL |
103 | a boolean flag indicating if the lower bound exists, |
104 | and LB_INCLUSIVE is a boolean flag indicating if the | |
105 | lower bound is inclusive or not. UB, HAS_UB, and | |
b8698a0f | 106 | UB_INCLUSIVE have the same meaning, but for upper |
c2699190 XDL |
107 | bound of the domain. */ |
108 | ||
109 | static inp_domain | |
110 | get_domain (int lb, bool has_lb, bool lb_inclusive, | |
111 | int ub, bool has_ub, bool ub_inclusive) | |
112 | { | |
113 | inp_domain domain; | |
114 | domain.lb = lb; | |
115 | domain.has_lb = has_lb; | |
116 | domain.is_lb_inclusive = lb_inclusive; | |
117 | domain.ub = ub; | |
118 | domain.has_ub = has_ub; | |
119 | domain.is_ub_inclusive = ub_inclusive; | |
120 | return domain; | |
121 | } | |
122 | ||
b8698a0f | 123 | /* A helper function to check the target format for the |
c2699190 | 124 | argument type. In this implementation, only IEEE formats |
b8698a0f | 125 | are supported. ARG is the call argument to be checked. |
c2699190 XDL |
126 | Returns true if the format is supported. To support other |
127 | target formats, function get_no_error_domain needs to be | |
b8698a0f L |
128 | enhanced to have range bounds properly computed. Since |
129 | the check is cheap (very small number of candidates | |
c2699190 XDL |
130 | to be checked), the result is not cached for each float type. */ |
131 | ||
132 | static bool | |
133 | check_target_format (tree arg) | |
134 | { | |
135 | tree type; | |
136 | enum machine_mode mode; | |
137 | const struct real_format *rfmt; | |
b8698a0f | 138 | |
c2699190 XDL |
139 | type = TREE_TYPE (arg); |
140 | mode = TYPE_MODE (type); | |
141 | rfmt = REAL_MODE_FORMAT (mode); | |
5d94a6d0 | 142 | if ((mode == SFmode |
ea8bce02 AS |
143 | && (rfmt == &ieee_single_format || rfmt == &mips_single_format |
144 | || rfmt == &motorola_single_format)) | |
5d94a6d0 | 145 | || (mode == DFmode |
ea8bce02 AS |
146 | && (rfmt == &ieee_double_format || rfmt == &mips_double_format |
147 | || rfmt == &motorola_double_format)) | |
c2699190 | 148 | /* For long double, we can not really check XFmode |
b8698a0f L |
149 | which is only defined on intel platforms. |
150 | Candidate pre-selection using builtin function | |
151 | code guarantees that we are checking formats | |
c2699190 | 152 | for long double modes: double, quad, and extended. */ |
b8698a0f | 153 | || (mode != SFmode && mode != DFmode |
c2699190 | 154 | && (rfmt == &ieee_quad_format |
5d94a6d0 | 155 | || rfmt == &mips_quad_format |
ea8bce02 | 156 | || rfmt == &ieee_extended_motorola_format |
b8698a0f L |
157 | || rfmt == &ieee_extended_intel_96_format |
158 | || rfmt == &ieee_extended_intel_128_format | |
c2699190 XDL |
159 | || rfmt == &ieee_extended_intel_96_round_53_format))) |
160 | return true; | |
161 | ||
162 | return false; | |
163 | } | |
164 | ||
165 | \f | |
166 | /* A helper function to help select calls to pow that are suitable for | |
167 | conditional DCE transformation. It looks for pow calls that can be | |
168 | guided with simple conditions. Such calls either have constant base | |
b8698a0f | 169 | values or base values converted from integers. Returns true if |
c2699190 XDL |
170 | the pow call POW_CALL is a candidate. */ |
171 | ||
172 | /* The maximum integer bit size for base argument of a pow call | |
173 | that is suitable for shrink-wrapping transformation. */ | |
174 | #define MAX_BASE_INT_BIT_SIZE 32 | |
175 | ||
176 | static bool | |
726a989a | 177 | check_pow (gimple pow_call) |
c2699190 XDL |
178 | { |
179 | tree base, expn; | |
180 | enum tree_code bc, ec; | |
181 | ||
726a989a | 182 | if (gimple_call_num_args (pow_call) != 2) |
c2699190 XDL |
183 | return false; |
184 | ||
726a989a RB |
185 | base = gimple_call_arg (pow_call, 0); |
186 | expn = gimple_call_arg (pow_call, 1); | |
c2699190 XDL |
187 | |
188 | if (!check_target_format (expn)) | |
189 | return false; | |
190 | ||
191 | bc = TREE_CODE (base); | |
192 | ec = TREE_CODE (expn); | |
193 | ||
194 | /* Folding candidates are not interesting. | |
195 | Can actually assert that it is already folded. */ | |
196 | if (ec == REAL_CST && bc == REAL_CST) | |
197 | return false; | |
198 | ||
199 | if (bc == REAL_CST) | |
200 | { | |
201 | /* Only handle a fixed range of constant. */ | |
202 | REAL_VALUE_TYPE mv; | |
203 | REAL_VALUE_TYPE bcv = TREE_REAL_CST (base); | |
204 | if (REAL_VALUES_EQUAL (bcv, dconst1)) | |
205 | return false; | |
206 | if (REAL_VALUES_LESS (bcv, dconst1)) | |
207 | return false; | |
208 | real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, 0, 1); | |
209 | if (REAL_VALUES_LESS (mv, bcv)) | |
210 | return false; | |
211 | return true; | |
212 | } | |
213 | else if (bc == SSA_NAME) | |
214 | { | |
6b4a85ad | 215 | tree base_val0, type; |
726a989a | 216 | gimple base_def; |
c2699190 XDL |
217 | int bit_sz; |
218 | ||
219 | /* Only handles cases where base value is converted | |
b8698a0f | 220 | from integer values. */ |
c2699190 | 221 | base_def = SSA_NAME_DEF_STMT (base); |
726a989a | 222 | if (gimple_code (base_def) != GIMPLE_ASSIGN) |
c2699190 XDL |
223 | return false; |
224 | ||
726a989a | 225 | if (gimple_assign_rhs_code (base_def) != FLOAT_EXPR) |
c2699190 | 226 | return false; |
726a989a | 227 | base_val0 = gimple_assign_rhs1 (base_def); |
c2699190 | 228 | |
6b4a85ad | 229 | type = TREE_TYPE (base_val0); |
c2699190 XDL |
230 | if (TREE_CODE (type) != INTEGER_TYPE) |
231 | return false; | |
232 | bit_sz = TYPE_PRECISION (type); | |
233 | /* If the type of the base is too wide, | |
234 | the resulting shrink wrapping condition | |
235 | will be too conservative. */ | |
236 | if (bit_sz > MAX_BASE_INT_BIT_SIZE) | |
237 | return false; | |
238 | ||
239 | return true; | |
240 | } | |
241 | else | |
242 | return false; | |
243 | } | |
244 | ||
245 | /* A helper function to help select candidate function calls that are | |
246 | suitable for conditional DCE. Candidate functions must have single | |
247 | valid input domain in this implementation except for pow (see check_pow). | |
248 | Returns true if the function call is a candidate. */ | |
249 | ||
250 | static bool | |
726a989a | 251 | check_builtin_call (gimple bcall) |
c2699190 XDL |
252 | { |
253 | tree arg; | |
254 | ||
726a989a | 255 | arg = gimple_call_arg (bcall, 0); |
c2699190 XDL |
256 | return check_target_format (arg); |
257 | } | |
258 | ||
259 | /* A helper function to determine if a builtin function call is a | |
260 | candidate for conditional DCE. Returns true if the builtin call | |
261 | is a candidate. */ | |
262 | ||
263 | static bool | |
726a989a | 264 | is_call_dce_candidate (gimple call) |
c2699190 XDL |
265 | { |
266 | tree fn; | |
267 | enum built_in_function fnc; | |
268 | ||
726a989a RB |
269 | /* Only potentially dead calls are considered. */ |
270 | if (gimple_call_lhs (call)) | |
c2699190 XDL |
271 | return false; |
272 | ||
726a989a RB |
273 | fn = gimple_call_fndecl (call); |
274 | if (!fn | |
b8698a0f | 275 | || !DECL_BUILT_IN (fn) |
c2699190 XDL |
276 | || (DECL_BUILT_IN_CLASS (fn) != BUILT_IN_NORMAL)) |
277 | return false; | |
278 | ||
279 | fnc = DECL_FUNCTION_CODE (fn); | |
280 | switch (fnc) | |
281 | { | |
282 | /* Trig functions. */ | |
283 | CASE_FLT_FN (BUILT_IN_ACOS): | |
284 | CASE_FLT_FN (BUILT_IN_ASIN): | |
285 | /* Hyperbolic functions. */ | |
286 | CASE_FLT_FN (BUILT_IN_ACOSH): | |
287 | CASE_FLT_FN (BUILT_IN_ATANH): | |
288 | CASE_FLT_FN (BUILT_IN_COSH): | |
289 | CASE_FLT_FN (BUILT_IN_SINH): | |
290 | /* Log functions. */ | |
291 | CASE_FLT_FN (BUILT_IN_LOG): | |
292 | CASE_FLT_FN (BUILT_IN_LOG2): | |
293 | CASE_FLT_FN (BUILT_IN_LOG10): | |
294 | CASE_FLT_FN (BUILT_IN_LOG1P): | |
295 | /* Exp functions. */ | |
296 | CASE_FLT_FN (BUILT_IN_EXP): | |
297 | CASE_FLT_FN (BUILT_IN_EXP2): | |
298 | CASE_FLT_FN (BUILT_IN_EXP10): | |
299 | CASE_FLT_FN (BUILT_IN_EXPM1): | |
300 | CASE_FLT_FN (BUILT_IN_POW10): | |
301 | /* Sqrt. */ | |
302 | CASE_FLT_FN (BUILT_IN_SQRT): | |
303 | return check_builtin_call (call); | |
304 | /* Special one: two argument pow. */ | |
305 | case BUILT_IN_POW: | |
306 | return check_pow (call); | |
307 | default: | |
308 | break; | |
309 | } | |
310 | ||
311 | return false; | |
312 | } | |
313 | ||
314 | \f | |
315 | /* A helper function to generate gimple statements for | |
316 | one bound comparison. ARG is the call argument to | |
317 | be compared with the bound, LBUB is the bound value | |
318 | in integer, TCODE is the tree_code of the comparison, | |
319 | TEMP_NAME1/TEMP_NAME2 are names of the temporaries, | |
320 | CONDS is a vector holding the produced GIMPLE statements, | |
321 | and NCONDS points to the variable holding the number | |
b8698a0f | 322 | of logical comparisons. CONDS is either empty or |
c2699190 XDL |
323 | a list ended with a null tree. */ |
324 | ||
325 | static void | |
b8698a0f | 326 | gen_one_condition (tree arg, int lbub, |
c2699190 XDL |
327 | enum tree_code tcode, |
328 | const char *temp_name1, | |
726a989a | 329 | const char *temp_name2, |
9771b263 | 330 | vec<gimple> conds, |
c2699190 XDL |
331 | unsigned *nconds) |
332 | { | |
333 | tree lbub_real_cst, lbub_cst, float_type; | |
334 | tree temp, tempn, tempc, tempcn; | |
726a989a | 335 | gimple stmt1, stmt2, stmt3; |
c2699190 XDL |
336 | |
337 | float_type = TREE_TYPE (arg); | |
338 | lbub_cst = build_int_cst (integer_type_node, lbub); | |
339 | lbub_real_cst = build_real_from_int_cst (float_type, lbub_cst); | |
340 | ||
341 | temp = create_tmp_var (float_type, temp_name1); | |
726a989a | 342 | stmt1 = gimple_build_assign (temp, arg); |
c2699190 | 343 | tempn = make_ssa_name (temp, stmt1); |
726a989a | 344 | gimple_assign_set_lhs (stmt1, tempn); |
c2699190 XDL |
345 | |
346 | tempc = create_tmp_var (boolean_type_node, temp_name2); | |
726a989a RB |
347 | stmt2 = gimple_build_assign (tempc, |
348 | fold_build2 (tcode, | |
349 | boolean_type_node, | |
350 | tempn, lbub_real_cst)); | |
c2699190 | 351 | tempcn = make_ssa_name (tempc, stmt2); |
726a989a RB |
352 | gimple_assign_set_lhs (stmt2, tempcn); |
353 | ||
354 | stmt3 = gimple_build_cond_from_tree (tempcn, NULL_TREE, NULL_TREE); | |
9771b263 DN |
355 | conds.quick_push (stmt1); |
356 | conds.quick_push (stmt2); | |
357 | conds.quick_push (stmt3); | |
c2699190 XDL |
358 | (*nconds)++; |
359 | } | |
360 | ||
361 | /* A helper function to generate GIMPLE statements for | |
362 | out of input domain check. ARG is the call argument | |
363 | to be runtime checked, DOMAIN holds the valid domain | |
364 | for the given function, CONDS points to the vector | |
b8698a0f L |
365 | holding the result GIMPLE statements. *NCONDS is |
366 | the number of logical comparisons. This function | |
c2699190 XDL |
367 | produces no more than two logical comparisons, one |
368 | for lower bound check, one for upper bound check. */ | |
369 | ||
370 | static void | |
371 | gen_conditions_for_domain (tree arg, inp_domain domain, | |
9771b263 | 372 | vec<gimple> conds, |
c2699190 XDL |
373 | unsigned *nconds) |
374 | { | |
375 | if (domain.has_lb) | |
376 | gen_one_condition (arg, domain.lb, | |
377 | (domain.is_lb_inclusive | |
378 | ? LT_EXPR : LE_EXPR), | |
379 | "DCE_COND_LB", "DCE_COND_LB_TEST", | |
380 | conds, nconds); | |
381 | ||
382 | if (domain.has_ub) | |
383 | { | |
384 | /* Now push a separator. */ | |
385 | if (domain.has_lb) | |
9771b263 | 386 | conds.quick_push (NULL); |
c2699190 XDL |
387 | |
388 | gen_one_condition (arg, domain.ub, | |
389 | (domain.is_ub_inclusive | |
390 | ? GT_EXPR : GE_EXPR), | |
391 | "DCE_COND_UB", "DCE_COND_UB_TEST", | |
392 | conds, nconds); | |
393 | } | |
394 | } | |
395 | ||
396 | ||
397 | /* A helper function to generate condition | |
398 | code for the y argument in call pow (some_const, y). | |
b8698a0f | 399 | See candidate selection in check_pow. Since the |
c2699190 XDL |
400 | candidates' base values have a limited range, |
401 | the guarded code generated for y are simple: | |
402 | if (y > max_y) | |
403 | pow (const, y); | |
404 | Note max_y can be computed separately for each | |
405 | const base, but in this implementation, we | |
406 | choose to compute it using the max base | |
407 | in the allowed range for the purpose of | |
408 | simplicity. BASE is the constant base value, | |
409 | EXPN is the expression for the exponent argument, | |
410 | *CONDS is the vector to hold resulting statements, | |
411 | and *NCONDS is the number of logical conditions. */ | |
412 | ||
413 | static void | |
414 | gen_conditions_for_pow_cst_base (tree base, tree expn, | |
9771b263 | 415 | vec<gimple> conds, |
c2699190 XDL |
416 | unsigned *nconds) |
417 | { | |
b8698a0f L |
418 | inp_domain exp_domain; |
419 | /* Validate the range of the base constant to make | |
c2699190 XDL |
420 | sure it is consistent with check_pow. */ |
421 | REAL_VALUE_TYPE mv; | |
422 | REAL_VALUE_TYPE bcv = TREE_REAL_CST (base); | |
423 | gcc_assert (!REAL_VALUES_EQUAL (bcv, dconst1) | |
424 | && !REAL_VALUES_LESS (bcv, dconst1)); | |
425 | real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, 0, 1); | |
426 | gcc_assert (!REAL_VALUES_LESS (mv, bcv)); | |
427 | ||
428 | exp_domain = get_domain (0, false, false, | |
429 | 127, true, false); | |
430 | ||
431 | gen_conditions_for_domain (expn, exp_domain, | |
432 | conds, nconds); | |
433 | } | |
434 | ||
435 | /* Generate error condition code for pow calls with | |
436 | non constant base values. The candidates selected | |
437 | have their base argument value converted from | |
438 | integer (see check_pow) value (1, 2, 4 bytes), and | |
439 | the max exp value is computed based on the size | |
440 | of the integer type (i.e. max possible base value). | |
441 | The resulting input domain for exp argument is thus | |
b8698a0f L |
442 | conservative (smaller than the max value allowed by |
443 | the runtime value of the base). BASE is the integer | |
444 | base value, EXPN is the expression for the exponent | |
445 | argument, *CONDS is the vector to hold resulting | |
446 | statements, and *NCONDS is the number of logical | |
c2699190 XDL |
447 | conditions. */ |
448 | ||
449 | static void | |
450 | gen_conditions_for_pow_int_base (tree base, tree expn, | |
9771b263 | 451 | vec<gimple> conds, |
c2699190 XDL |
452 | unsigned *nconds) |
453 | { | |
726a989a | 454 | gimple base_def; |
0f900dfa | 455 | tree base_val0; |
6b4a85ad | 456 | tree int_type; |
c2699190 | 457 | tree temp, tempn; |
726a989a RB |
458 | tree cst0; |
459 | gimple stmt1, stmt2; | |
c2699190 XDL |
460 | int bit_sz, max_exp; |
461 | inp_domain exp_domain; | |
462 | ||
463 | base_def = SSA_NAME_DEF_STMT (base); | |
726a989a | 464 | base_val0 = gimple_assign_rhs1 (base_def); |
6b4a85ad | 465 | int_type = TREE_TYPE (base_val0); |
c2699190 | 466 | bit_sz = TYPE_PRECISION (int_type); |
b8698a0f | 467 | gcc_assert (bit_sz > 0 |
c2699190 XDL |
468 | && bit_sz <= MAX_BASE_INT_BIT_SIZE); |
469 | ||
470 | /* Determine the max exp argument value according to | |
471 | the size of the base integer. The max exp value | |
472 | is conservatively estimated assuming IEEE754 double | |
473 | precision format. */ | |
474 | if (bit_sz == 8) | |
475 | max_exp = 128; | |
476 | else if (bit_sz == 16) | |
477 | max_exp = 64; | |
478 | else | |
0f900dfa JJ |
479 | { |
480 | gcc_assert (bit_sz == MAX_BASE_INT_BIT_SIZE); | |
481 | max_exp = 32; | |
482 | } | |
c2699190 XDL |
483 | |
484 | /* For pow ((double)x, y), generate the following conditions: | |
485 | cond 1: | |
486 | temp1 = x; | |
487 | if (temp1 <= 0) | |
488 | ||
489 | cond 2: | |
490 | temp2 = y; | |
491 | if (temp2 > max_exp_real_cst) */ | |
492 | ||
493 | /* Generate condition in reverse order -- first | |
494 | the condition for the exp argument. */ | |
495 | ||
496 | exp_domain = get_domain (0, false, false, | |
497 | max_exp, true, true); | |
498 | ||
499 | gen_conditions_for_domain (expn, exp_domain, | |
500 | conds, nconds); | |
501 | ||
502 | /* Now generate condition for the base argument. | |
503 | Note it does not use the helper function | |
504 | gen_conditions_for_domain because the base | |
505 | type is integer. */ | |
506 | ||
507 | /* Push a separator. */ | |
9771b263 | 508 | conds.quick_push (NULL); |
c2699190 XDL |
509 | |
510 | temp = create_tmp_var (int_type, "DCE_COND1"); | |
511 | cst0 = build_int_cst (int_type, 0); | |
726a989a | 512 | stmt1 = gimple_build_assign (temp, base_val0); |
c2699190 | 513 | tempn = make_ssa_name (temp, stmt1); |
726a989a RB |
514 | gimple_assign_set_lhs (stmt1, tempn); |
515 | stmt2 = gimple_build_cond (LE_EXPR, tempn, cst0, NULL_TREE, NULL_TREE); | |
c2699190 | 516 | |
9771b263 DN |
517 | conds.quick_push (stmt1); |
518 | conds.quick_push (stmt2); | |
c2699190 XDL |
519 | (*nconds)++; |
520 | } | |
521 | ||
522 | /* Method to generate conditional statements for guarding conditionally | |
523 | dead calls to pow. One or more statements can be generated for | |
524 | each logical condition. Statement groups of different conditions | |
9771b263 | 525 | are separated by a NULL tree and they are stored in the vec |
c2699190 XDL |
526 | conds. The number of logical conditions are stored in *nconds. |
527 | ||
528 | See C99 standard, 7.12.7.4:2, for description of pow (x, y). | |
529 | The precise condition for domain errors are complex. In this | |
530 | implementation, a simplified (but conservative) valid domain | |
531 | for x and y are used: x is positive to avoid dom errors, while | |
532 | y is smaller than a upper bound (depending on x) to avoid range | |
533 | errors. Runtime code is generated to check x (if not constant) | |
534 | and y against the valid domain. If it is out, jump to the call, | |
535 | otherwise the call is bypassed. POW_CALL is the call statement, | |
536 | *CONDS is a vector holding the resulting condition statements, | |
537 | and *NCONDS is the number of logical conditions. */ | |
538 | ||
539 | static void | |
9771b263 | 540 | gen_conditions_for_pow (gimple pow_call, vec<gimple> conds, |
c2699190 XDL |
541 | unsigned *nconds) |
542 | { | |
543 | tree base, expn; | |
0f900dfa | 544 | enum tree_code bc; |
c2699190 | 545 | |
77a74ed7 | 546 | gcc_checking_assert (check_pow (pow_call)); |
c2699190 XDL |
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 | |
9771b263 | 676 | gen_shrink_wrap_conditions (gimple bi_call, vec<gimple> 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 | ||
9771b263 DN |
683 | gcc_assert (nconds && conds.exists ()); |
684 | gcc_assert (conds.length () == 0); | |
726a989a | 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; | |
c2699190 XDL |
723 | unsigned tn_cond_stmts, nconds; |
724 | unsigned ci; | |
726a989a RB |
725 | gimple cond_expr = NULL; |
726 | gimple cond_expr_start; | |
c2699190 | 727 | tree bi_call_label_decl; |
726a989a | 728 | gimple bi_call_label; |
c2699190 | 729 | |
00f96dc9 | 730 | auto_vec<gimple, 12> conds; |
c2699190 XDL |
731 | gen_shrink_wrap_conditions (bi_call, conds, &nconds); |
732 | ||
733 | /* This can happen if the condition generator decides | |
734 | it is not beneficial to do the transformation. Just | |
b8698a0f | 735 | return false and do not do any transformation for |
c2699190 XDL |
736 | the call. */ |
737 | if (nconds == 0) | |
07687835 | 738 | return false; |
c2699190 | 739 | |
726a989a | 740 | bi_call_bb = gimple_bb (bi_call); |
c2699190 | 741 | |
7a460594 JJ |
742 | /* Now find the join target bb -- split bi_call_bb if needed. */ |
743 | if (stmt_ends_bb_p (bi_call)) | |
744 | { | |
745 | /* If the call must be the last in the bb, don't split the block, | |
746 | it could e.g. have EH edges. */ | |
747 | join_tgt_in_edge_from_call = find_fallthru_edge (bi_call_bb->succs); | |
748 | if (join_tgt_in_edge_from_call == NULL) | |
07687835 | 749 | return false; |
7a460594 JJ |
750 | } |
751 | else | |
752 | join_tgt_in_edge_from_call = split_block (bi_call_bb, bi_call); | |
c2699190 | 753 | |
726a989a | 754 | bi_call_bsi = gsi_for_stmt (bi_call); |
c2699190 XDL |
755 | |
756 | join_tgt_bb = join_tgt_in_edge_from_call->dest; | |
757 | ||
758 | /* Now it is time to insert the first conditional expression | |
759 | into bi_call_bb and split this bb so that bi_call is | |
760 | shrink-wrapped. */ | |
9771b263 | 761 | tn_cond_stmts = conds.length (); |
c2699190 | 762 | cond_expr = NULL; |
9771b263 | 763 | cond_expr_start = conds[0]; |
c2699190 XDL |
764 | for (ci = 0; ci < tn_cond_stmts; ci++) |
765 | { | |
9771b263 | 766 | gimple c = conds[ci]; |
c2699190 XDL |
767 | gcc_assert (c || ci != 0); |
768 | if (!c) | |
769 | break; | |
726a989a | 770 | gsi_insert_before (&bi_call_bsi, c, GSI_SAME_STMT); |
c2699190 XDL |
771 | cond_expr = c; |
772 | } | |
773 | nconds--; | |
774 | ci++; | |
726a989a | 775 | gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND); |
c2699190 XDL |
776 | |
777 | /* Now the label. */ | |
c2255bc4 | 778 | bi_call_label_decl = create_artificial_label (gimple_location (bi_call)); |
726a989a RB |
779 | bi_call_label = gimple_build_label (bi_call_label_decl); |
780 | gsi_insert_before (&bi_call_bsi, bi_call_label, GSI_SAME_STMT); | |
c2699190 XDL |
781 | |
782 | bi_call_in_edge0 = split_block (bi_call_bb, cond_expr); | |
783 | bi_call_in_edge0->flags &= ~EDGE_FALLTHRU; | |
784 | bi_call_in_edge0->flags |= EDGE_TRUE_VALUE; | |
785 | guard_bb0 = bi_call_bb; | |
786 | bi_call_bb = bi_call_in_edge0->dest; | |
b8698a0f | 787 | join_tgt_in_edge_fall_thru = make_edge (guard_bb0, join_tgt_bb, |
c2699190 XDL |
788 | EDGE_FALSE_VALUE); |
789 | ||
790 | bi_call_in_edge0->probability = REG_BR_PROB_BASE * ERR_PROB; | |
245ef160 JH |
791 | bi_call_in_edge0->count = |
792 | apply_probability (guard_bb0->count, | |
793 | bi_call_in_edge0->probability); | |
c2699190 | 794 | join_tgt_in_edge_fall_thru->probability = |
245ef160 JH |
795 | inverse_probability (bi_call_in_edge0->probability); |
796 | join_tgt_in_edge_fall_thru->count = | |
797 | guard_bb0->count - bi_call_in_edge0->count; | |
c2699190 XDL |
798 | |
799 | /* Code generation for the rest of the conditions */ | |
800 | guard_bb = guard_bb0; | |
801 | while (nconds > 0) | |
802 | { | |
803 | unsigned ci0; | |
804 | edge bi_call_in_edge; | |
726a989a | 805 | gimple_stmt_iterator guard_bsi = gsi_for_stmt (cond_expr_start); |
c2699190 | 806 | ci0 = ci; |
9771b263 | 807 | cond_expr_start = conds[ci0]; |
c2699190 XDL |
808 | for (; ci < tn_cond_stmts; ci++) |
809 | { | |
9771b263 | 810 | gimple c = conds[ci]; |
c2699190 XDL |
811 | gcc_assert (c || ci != ci0); |
812 | if (!c) | |
813 | break; | |
726a989a | 814 | gsi_insert_before (&guard_bsi, c, GSI_SAME_STMT); |
c2699190 XDL |
815 | cond_expr = c; |
816 | } | |
817 | nconds--; | |
818 | ci++; | |
726a989a | 819 | gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND); |
c2699190 XDL |
820 | guard_bb_in_edge = split_block (guard_bb, cond_expr); |
821 | guard_bb_in_edge->flags &= ~EDGE_FALLTHRU; | |
822 | guard_bb_in_edge->flags |= EDGE_FALSE_VALUE; | |
823 | ||
824 | bi_call_in_edge = make_edge (guard_bb, bi_call_bb, EDGE_TRUE_VALUE); | |
825 | ||
826 | bi_call_in_edge->probability = REG_BR_PROB_BASE * ERR_PROB; | |
245ef160 JH |
827 | bi_call_in_edge->count = |
828 | apply_probability (guard_bb->count, | |
829 | bi_call_in_edge->probability); | |
c2699190 | 830 | guard_bb_in_edge->probability = |
245ef160 JH |
831 | inverse_probability (bi_call_in_edge->probability); |
832 | guard_bb_in_edge->count = guard_bb->count - bi_call_in_edge->count; | |
c2699190 XDL |
833 | } |
834 | ||
c2699190 XDL |
835 | if (dump_file && (dump_flags & TDF_DETAILS)) |
836 | { | |
837 | location_t loc; | |
726a989a | 838 | loc = gimple_location (bi_call); |
c2699190 XDL |
839 | fprintf (dump_file, |
840 | "%s:%d: note: function call is shrink-wrapped" | |
841 | " into error conditions.\n", | |
842 | LOCATION_FILE (loc), LOCATION_LINE (loc)); | |
843 | } | |
844 | ||
845 | return true; | |
846 | } | |
847 | ||
848 | /* The top level function for conditional dead code shrink | |
849 | wrapping transformation. */ | |
850 | ||
851 | static bool | |
9771b263 | 852 | shrink_wrap_conditional_dead_built_in_calls (vec<gimple> calls) |
c2699190 XDL |
853 | { |
854 | bool changed = false; | |
855 | unsigned i = 0; | |
856 | ||
9771b263 | 857 | unsigned n = calls.length (); |
b8698a0f | 858 | if (n == 0) |
c2699190 XDL |
859 | return false; |
860 | ||
861 | for (; i < n ; i++) | |
862 | { | |
9771b263 | 863 | gimple bi_call = calls[i]; |
c2699190 XDL |
864 | changed |= shrink_wrap_one_built_in_call (bi_call); |
865 | } | |
866 | ||
867 | return changed; | |
868 | } | |
869 | ||
be55bfe6 TS |
870 | namespace { |
871 | ||
872 | const pass_data pass_data_call_cdce = | |
873 | { | |
874 | GIMPLE_PASS, /* type */ | |
875 | "cdce", /* name */ | |
876 | OPTGROUP_NONE, /* optinfo_flags */ | |
877 | true, /* has_execute */ | |
878 | TV_TREE_CALL_CDCE, /* tv_id */ | |
879 | ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
880 | 0, /* properties_provided */ | |
881 | 0, /* properties_destroyed */ | |
882 | 0, /* todo_flags_start */ | |
883 | TODO_verify_ssa, /* todo_flags_finish */ | |
884 | }; | |
885 | ||
886 | class pass_call_cdce : public gimple_opt_pass | |
887 | { | |
888 | public: | |
889 | pass_call_cdce (gcc::context *ctxt) | |
890 | : gimple_opt_pass (pass_data_call_cdce, ctxt) | |
891 | {} | |
892 | ||
893 | /* opt_pass methods: */ | |
894 | virtual bool gate (function *fun) | |
895 | { | |
896 | /* The limit constants used in the implementation | |
897 | assume IEEE floating point format. Other formats | |
898 | can be supported in the future if needed. */ | |
899 | return flag_tree_builtin_call_dce != 0 | |
900 | && optimize_function_for_speed_p (fun); | |
901 | } | |
c2699190 | 902 | |
be55bfe6 TS |
903 | virtual unsigned int execute (function *); |
904 | ||
905 | }; // class pass_call_cdce | |
906 | ||
907 | unsigned int | |
908 | pass_call_cdce::execute (function *fun) | |
c2699190 XDL |
909 | { |
910 | basic_block bb; | |
726a989a | 911 | gimple_stmt_iterator i; |
c2699190 | 912 | bool something_changed = false; |
ef062b13 | 913 | auto_vec<gimple> cond_dead_built_in_calls; |
be55bfe6 | 914 | FOR_EACH_BB_FN (bb, fun) |
c2699190 XDL |
915 | { |
916 | /* Collect dead call candidates. */ | |
726a989a | 917 | for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i)) |
c2699190 | 918 | { |
726a989a RB |
919 | gimple stmt = gsi_stmt (i); |
920 | if (is_gimple_call (stmt) | |
c2699190 XDL |
921 | && is_call_dce_candidate (stmt)) |
922 | { | |
923 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
924 | { | |
925 | fprintf (dump_file, "Found conditional dead call: "); | |
726a989a | 926 | print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
c2699190 XDL |
927 | fprintf (dump_file, "\n"); |
928 | } | |
9771b263 DN |
929 | if (!cond_dead_built_in_calls.exists ()) |
930 | cond_dead_built_in_calls.create (64); | |
931 | cond_dead_built_in_calls.safe_push (stmt); | |
c2699190 XDL |
932 | } |
933 | } | |
934 | } | |
935 | ||
9771b263 | 936 | if (!cond_dead_built_in_calls.exists ()) |
6b672a29 JJ |
937 | return 0; |
938 | ||
939 | something_changed | |
940 | = shrink_wrap_conditional_dead_built_in_calls (cond_dead_built_in_calls); | |
c2699190 | 941 | |
c2699190 XDL |
942 | if (something_changed) |
943 | { | |
944 | free_dominance_info (CDI_DOMINATORS); | |
945 | free_dominance_info (CDI_POST_DOMINATORS); | |
5006671f RG |
946 | /* As we introduced new control-flow we need to insert PHI-nodes |
947 | for the call-clobbers of the remaining call. */ | |
be55bfe6 | 948 | mark_virtual_operands_for_renaming (fun); |
c0e50f72 | 949 | return TODO_update_ssa; |
c2699190 | 950 | } |
c0e50f72 RB |
951 | |
952 | return 0; | |
c2699190 XDL |
953 | } |
954 | ||
27a4cd48 DM |
955 | } // anon namespace |
956 | ||
957 | gimple_opt_pass * | |
958 | make_pass_call_cdce (gcc::context *ctxt) | |
959 | { | |
960 | return new pass_call_cdce (ctxt); | |
961 | } |