[all-commits] [llvm/llvm-project] f885c0: Don't widen shuffle element with AVX512

[Luo, Yuanke via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f885c08034feaeb955bd74e3093d245125aa075d
      https://github.com/llvm/llvm-project/commit/f885c08034feaeb955bd74e3093d245125aa075d
  Author: Luo, Yuanke <yuanke.luo at intel.com>
  Date:   2022-10-12 (Wed, 12 Oct 2022)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/avx512-shuffles/shuffle-blend.ll
    M llvm/test/CodeGen/X86/combine-sdiv.ll

  Log Message:
  -----------
  Don't widen shuffle element with AVX512

Fix crash issue of D129537 and reopen it.

Currently the X86 shuffle lowering would widen the element type for
shuffle if the mask element value is adjacent. For below example

  %t2 = add nsw <16 x i32> %t0, %t1
  %t3 = sub nsw <16 x i32> %t0, %t1
  %t4 = shufflevector <16 x i32> %t2, <16 x i32> %t3,
                      <16 x i32> <i32 16, i32 17, i32 2, i32 3, i32 4,
                       i32 5, i32 6, i32 7, i32 8, i32 9, i32 10,
                       i32 11, i32 12, i32 13, i32 14, i32 15>

  ret <16 x i32> %t4

Compiler would transform the shuffle to
  %t4 = shufflevector <8 x i64> %t2, <8 x i64> %t3,
                      <8 x i64> <i32 8, i32 1, i32 2, i32 3, i32 4,
                                 i32 5, i32 6, i32 7>
This may lose the oppotunity to let ISel select mask instruction when
avx512 is enabled.

This patch is to prevent the tranform when avx512 feature is enabled.
Thank Simon for the idea.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D130830