On February 4, 2015 9:35:13 AM CET, Jakub Jelinek <ja...@redhat.com> wrote: >On Wed, Feb 04, 2015 at 04:21:43AM -0200, Alexandre Oliva wrote: >> I'm a bit surprised the gimple layer does not even attempt to >simplify >> them, but I didn't try to tackle that, since I was not even sure this >> was a useful optimization. After all, how often do we see xor of and >of >> xor of and of xor of... in the wild, rather than in pathological >> testcases? :-) But hey, at least the rtl simplification is cheap, so >> why not? > >I think we should teach at least VRP to simplify debug stmts similarly >how >it simplifies normal comparisons etc. using value ranges, but that >would be >stage1 material.
So I suppose this is only about debug exprs and we optimize regular gimple well? Otherwise adding some patterns to match.PD could help. Richard. >> Regstrapped on x86_64-linux-gnu and i686-pc-linux-gnu. Ok to >install? >> >> for gcc/ChangeLog >> >> * simplify-rtx.c (simplify_binary_operation_1): Simplify one >> of two XORs that have an intervening AND or IOR. > >Ok, thanks. > > Jakub
