[PATCH] D95406: [GlobalISel][Localizer] Don't localize phi operands which are used more than once in the phi.

[Amara Emerson via Phabricator via llvm-commits]

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The current algorithm just tries to localize defs as far as they can go, and in the case of G_PHI operands, it clones the def into the predecessor block for each incoming edge. When multiple edges have the same register value, this can cause unnecessary code bloat, and inhibit later optimizations.

This change checks if a given phi operand is unique in the phi, if not the def of that register is not localized to the predecessor.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D95406

Files:
  llvm/include/llvm/CodeGen/GlobalISel/Localizer.h
  llvm/lib/CodeGen/GlobalISel/Localizer.cpp
  llvm/test/CodeGen/AArch64/GlobalISel/localizer.mir

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