[PATCH] D44402: [DAGCombiner] Fold (zext (and/or/xor (shl/shr (load x), cst), cst))

[Guozhi Wei via Phabricator via llvm-commits]

Carrot created this revision.

In our real world application, we found the following optimization is missed in DAGCombiner

(zext (and/or/xor (shl/shr (load x), cst), cst)) -> (and/or/xor (shl/shr (zextload x), (zext cst)), (zext cst))

If the user of original zext is an add, it may enable further lea optimization on x86.

This patch add a new function CombineZExtLogicopShiftLoad to do this optimization.


Repository:
  rL LLVM

https://reviews.llvm.org/D44402

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/X86/zext-logicop-shift-load.ll

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