[PATCH] D48877: [X86][BtVer2][MCA] Recognize CMPEQ one-idioms

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

On Intel hardware, in register renaming it basically rewrites the input register to an internal all zeros register. The instruction still needs to execute and now compares zero with zero and gets all ones. But by rewriting the input register to all zeros instead of the real input, the instruction doesn't need to wait for the previous writer of the input register to execute.


Repository:
  rL LLVM

https://reviews.llvm.org/D48877