2014-11-17 20:36 GMT+00:00 Jeff Law <l...@redhat.com>: > On 11/17/14 02:26, Jiong Wang wrote: >> >> as Pinski reported at >> >> https://gcc.gnu.org/ml/gcc-patches/2014-11/msg01967.html >> >> the previosu LR free patch on AArch64 cause one gcc_assert in >> lra-elimination.c >> >> one of the problem is that gcc_assert is too strict and overkilled some >> valid cases. >> >> the purpose of that assert is described here >> >> https://gcc.gnu.org/ml/gcc-patches/2013-12/msg00151.html >> >> and I checked the code, it's purpose is to prohibit the following >> scenario: >> >> FP decided to be not required earlier, and then be required later. >> >> that assert prohibit above situation, because it will cause bad code >> generation. FP >> may be allocated earlier while because later it identified to be >> required as fixed purpose, then >> all those pseudo allocated to FP need to be spilled. >> >> so, this check will only make sense when that reg is not fixed itself. >> >> this patch relax that gcc_assert for fixed registers. >> >> the problem reported by Pinski fixed also, because FP of AArch64 is fixed. >> >> bootstrap ok on AArch64 and X86-64. >> no regression on X86-64. >> Pinskia's testcase passed on AArch64 on his code branch. >> >> ok for trunk? >> >> gcc/ >> * lra-eliminations.c (update_reg_eliminate): Relax gcc_assert for >> fixed registers. > > OK for the trunk. It'd be useful to have a test, but my understanding is > you need Pinski's modifications to trigger the failure. Correct?
Jeff, thanks for review. Yes, this can only be reproduced on pinskia's private branch "apinski/thunderx-cost". Regards, Jiong > > Jeff >
