[PATCH] D72356: [TargetLowering][X86] TeachSimplifyDemanedBits to handle cases where only the sign bit is demanded and can be passed through

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: RKSimon, spatel.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.
craig.topper added a parent revision: D72354: [X86] Enable v2i64->v2f32 uint_to_fp code in ReplaceNodeResults on SSE4.1 target .

If we're doing a compare that only tests the sign bit and only the sign bit is demanded, we can just bypass the node. This removes one of the blend dependencies in our v2i64->v2f32 uint_to_fp codegen on pre-sse4.2 targets.


https://reviews.llvm.org/D72356

Files:
  llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
  llvm/test/CodeGen/X86/vec_int_to_fp.ll

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