[PATCH] D77300: [X86] Improve combineVectorShiftImm

[Jay Foad via Phabricator via llvm-commits]

foad created this revision.
foad added reviewers: RKSimon, craig.topper.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.
foad added a child revision: D77301: [TargetLowering] Improve expansion of FSHL/FSHR.

Fold (shift (shift X, C2), C1) -> (shift X, (C1 + C2)) for logical as
well as arithmetic shifts. This is needed to prevent regressions from
an upcoming funnel shift expansion change.

While we're here, fold (VSRAI -1, C) -> -1 too.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77300

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/midpoint-int-vec-128.ll
  llvm/test/CodeGen/X86/midpoint-int-vec-256.ll
  llvm/test/CodeGen/X86/midpoint-int-vec-512.ll

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