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On May 31, 2013, at 4:07 PM, Joe Matarazzo <joe.matarazzo at gmail.com> wrote: > The register coalescer treats virtual super register classes -- a sequential register range composed of multiple hardware registers -- as a register with sub registers. When making coalescing decisions it thinks that the virtual super reg interferes with sub reg instances, even though in reality they

...work around this? It causes unnecessary copies. > > Is this happening on trunk, or are you using an old version of LLVM? > > /jakob > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130531/d4087018/attachment.html>

The register coalescer treats virtual super register classes -- a sequential register range composed of multiple hardware registers -- as a register with sub registers. When making coalescing decisions it thinks that the virtual super reg interferes with sub reg instances, even though in reality they shouldn't conflict. That is, they are individual registers and would be better compared as