https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87984
--- Comment #27 from rguenther at suse dot de <rguenther at suse dot de> --- On February 8, 2019 6:35:29 PM GMT+01:00, "jakub at gcc dot gnu.org" <gcc-bugzi...@gcc.gnu.org> wrote: >https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87984 > >--- Comment #24 from Jakub Jelinek <jakub at gcc dot gnu.org> --- >FRE doesn't, as that breaks the #c9 testcase. > a = 1; > __asm__("add %1, %0" : "=r" o_12 : "r" a, "0" 0); > __asm__ __volatile__("xor %%eax, %%eax" : : : "eax"); > i_13 = 1; > a = 1; > __asm__("add %1, %0" : "=r" o_18 : "r" a, "0" o_12); > __asm__ __volatile__("xor %%eax, %%eax" : : : "eax"); > i_19 = 2; > a = 1; > __asm__("add %1, %0" : "=r" o_24 : "r" a, "0" o_18); > __asm__ __volatile__("xor %%eax, %%eax" : : : "eax"); > i_25 = 3; >to: > a = 1; > __asm__("add %1, %0" : "=r" o_12 : "r" a, "0" 0); > __asm__ __volatile__("xor %%eax, %%eax" : : : "eax"); > __asm__("add %1, %0" : "=r" o_18 : "r" a, "0" o_12); > __asm__ __volatile__("xor %%eax, %%eax" : : : "eax"); > __asm__("add %1, %0" : "=r" o_24 : "r" a, "0" o_18); > __asm__ __volatile__("xor %%eax, %%eax" : : : "eax"); >If SCCVN would never record values for DECL_HARD_REGISTER vars or >something >similar, it wouldn't do this. OK. I guess I misremember and it hurt never elides sets of reg vars. Richard.
