https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81877
--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> --- On Thu, 17 Aug 2017, marxin at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81877 > > --- Comment #3 from Martin Liška <marxin at gcc dot gnu.org> --- > Created attachment 41993 > --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41993&action=edit > Patch to reduce the problem > > Can be reduced by given patch. The function is called for following loop: > > <bb 45>: > # b_118 = PHI <b_424(28), b_75(56)> > # count.30_122 = PHI <count.30_38(28), count.30_76(56)> > c = 0.0; > if (le.52_14 <= 0) > goto <bb 37>; > else > goto <bb 29>; > > <bb 29>: > _253 = le.52_14 + -1; > if (le.52_14 < _253) > goto <bb 37>; > else > goto <bb 30>; > > <bb 30>: > _256 = le.52_14 * 2; > if (_256 < -1) > goto <bb 37>; > else > goto <bb 31>; > > <bb 31>: > k2_262 = le.52_14 + 1; > _269 = _253 + k2_262; > j02_270 = _269 + 1; > j04_275 = _269 + 2; > M.0_403 = MIN_EXPR <_253, 0>; > mo_278 = M.0_403 + 1; > M.1_391 = MIN_EXPR <k2_262, 0>; > if (k2_262 < 0) > goto <bb 32>; > else > goto <bb 33>; > > <bb 32>: > m_280 = 1 - M.1_391; > > <bb 33>: > # m_281 = PHI <1(31), m_280(32)> > if (mo_278 < m_281) > goto <bb 37>; > else > goto <bb 34>; > > <bb 34>: > _284 = fak[0]; > _285 = _284 - 2.99573230743408203125e+0; > _286 = (integer(kind=8)) j02_270; > _287 = _286 + -1; > _288 = fak[_287]; > _289 = _285 + _288; > _293 = _284 + _289; > _294 = (integer(kind=8)) j04_275; > _295 = _294 + -1; > _296 = fak[_295]; > del_297 = _293 - _296; > j6_299 = le.52_14 + 2; > j7_301 = le.52_14 + 2; > _308 = _284 + del_297; > _313 = _284 + _308; > _315 = (integer(kind=8)) le.52_14; > _316 = _315 + -1; > _317 = fak[_316]; > _318 = _313 + _317; > _319 = (integer(kind=8)) j6_299; > _320 = _319 + -1; > _321 = fak[_320]; > _322 = _318 + _321; > _323 = (integer(kind=8)) j7_301; > _324 = _323 + -1; > _325 = fak[_324]; > _326 = _322 + _325; > _330 = _317 + _326; > _331 = ((_330)); > sym_332 = _331 * 5.0e-1; > > <bb 35>: > # k_333 = PHI <m_281(34), k_369(57)> > j2_335 = k2_262 + k_333; > _336 = -k_333; > j3_337 = 2 - k_333; > j4_339 = 2 - k_333; > _340 = _253 - k_333; > j5_341 = _340 + 2; > _342 = (integer(kind=8)) k_333; > _343 = _342 + -1; > _344 = fak[_343]; > _345 = sym_332 - _344; > _349 = _345 - _344; > _350 = (integer(kind=8)) j2_335; > _351 = _350 + -1; > _352 = fak[_351]; > _353 = _349 - _352; > _354 = (integer(kind=8)) j3_337; > _355 = _354 + -1; > _356 = fak[_355]; > _357 = _353 - _356; > _358 = (integer(kind=8)) j4_339; > _359 = _358 + -1; > _360 = fak[_359]; > _361 = _357 - _360; > _362 = (integer(kind=8)) j5_341; > _363 = _362 + -1; > _364 = fak[_363]; > _365 = _361 - _364; > _366 = __builtin_expf (_365); > _367 = c; > _368 = _366 - _367; > c = _368; > k_369 = k_333 + 1; > if (mo_278 == k_333) > goto <bb 36>; > else > goto <bb 57>; > > <bb 57>: > goto <bb 35>; > > <bb 36>: > _370 = _253 + k_333; > _371 = _370 + 1; > _372 = _371 << 1; > _373 = _372 & 2; > _374 = 1 - _373; > _375 = (real(kind=4)) _374; > _377 = _368 * _375; > c = _377; > > <bb 37>: > c.58_18 = c; > b_75 = c.58_18 + b_118; > count.30_76 = count.30_122 + -1; > if (count.30_76 <= 0) > goto <bb 38>; > else > goto <bb 56>; > > <bb 56>: > goto <bb 45>; > > where we return true for 'c'. The function's comment: > > /* Returns true if REF is independent on all other memory references in > LOOP. */ > > which is probably wrong as there are various memory references that influence > value of the 'c'. Not in the above code? Well, direct accesses of c obviously. I will have a look. > I have very small experience in loop optimizations, thus leaving to somebody > more skilled. > >
