forked from OSchip/llvm-project
d683a22dd2
> For functions where esi is used as base pointer, we would previously fall ba > from lowering memcpy with "rep movs" because that clobbers esi. > > With this patch, we just store esi in another physical register, and restore > it afterwards. This adds a little bit of register preassure, but the more > efficient memcpy should be worth it. > > Differential Revision: http://llvm-reviews.chandlerc.com/D2968 This didn't work. I was ending up with code like this: lea edi,[esi+38h] mov ecx,0Fh mov edx,esi mov esi,ebx rep movs dword ptr es:[edi],dword ptr [esi] lea ecx,[esi+74h] <-- Ooops, we're now using esi before restoring it from edx. add ebx,3Ch mov esi,edx I guess if we want to do this we need stronger glue or something, or doing the expansion much later. llvm-svn: 204829 |
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