[PATCH] D54658: [X86] Add an AND with 255 to the v16i8 LowerMUL path with AVX2, but not AVX512

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: RKSimon, spatel.

This will coax the truncate lowering to emit an extract_subvector and a packuswb instead of an extract_subvector, 2 pshufbs, and a punpcklqdq. But don't do this if we have an AVX512 truncate instruction available.


https://reviews.llvm.org/D54658

Files:
  lib/Target/X86/X86ISelLowering.cpp
  test/CodeGen/X86/avx2-arith.ll
  test/CodeGen/X86/combine-mul.ll
  test/CodeGen/X86/pmul.ll
  test/CodeGen/X86/vector-mul.ll
  test/CodeGen/X86/vector-reduce-mul.ll
  test/CodeGen/X86/vector-shift-shl-128.ll

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