[PATCH] D57789: [CGP] form usub with overflow from sub+icmp

[Sanjay Patel via Phabricator via llvm-commits]

spatel updated this revision to Diff 186286.
spatel added a comment.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

Patch updated:
Side-step controversy by adding a TLI hook. This should preserve existing behavior for uaddo and usubo for all targets, except x86 which now allows usubo formation. It seems likely that other targets like AArch64, AMDGPU, and PPC should allow usubo too, but they can do that selectively as follow-ups.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57789/new/

https://reviews.llvm.org/D57789

Files:
  llvm/include/llvm/CodeGen/TargetLowering.h
  llvm/lib/CodeGen/CodeGenPrepare.cpp
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/lib/Target/X86/X86ISelLowering.h
  llvm/test/CodeGen/X86/cgp-usubo.ll
  llvm/test/CodeGen/X86/lsr-loop-exit-cond.ll
  llvm/test/Transforms/CodeGenPrepare/X86/overflow-intrinsics.ll

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