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(For X86) Enhancement to add-carray/sub-borrow (adc/sbb) optimization.
authorShuxin Yang <shuxin.llvm@gmail.com>
Wed, 31 Oct 2012 23:11:48 +0000 (23:11 +0000)
committerShuxin Yang <shuxin.llvm@gmail.com>
Wed, 31 Oct 2012 23:11:48 +0000 (23:11 +0000)
commit01efdd6c283aebeb911bebf83429ac6f4e141b94
tree88e354fc592f656ed8e5ea6a6ca21d37d941dc8ctree | snapshot
parent6fd25ac3e27da5295e002391c162644976923d05commit | diff
(For X86) Enhancement to add-carray/sub-borrow (adc/sbb) optimization.

  The adc/sbb optimization is to able to convert following expression
into a single adc/sbb instruction:
  (ult) ... = x + 1 // where the ult is unsigned-less-than comparison
  (ult) ... = x - 1

  This change is to flip the "x >u y" (i.e. ugt comparison) in order
to expose the adc/sbb opportunity.

llvm-svn: 167180
llvm/lib/Target/X86/X86ISelLowering.cpp diff | blob | history
llvm/test/CodeGen/X86/add-of-carry.ll diff | blob | history
llvm/test/CodeGen/X86/jump_sign.ll diff | blob | history
Domain: System / Toolchain;