[all-commits] [llvm/llvm-project] 6bb717: [X86] convertShiftLeftToScale - improve vXi8 const...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6bb71738e26ca3ba4f2894bf6542bf33625a52c0
      https://github.com/llvm/llvm-project/commit/6bb71738e26ca3ba4f2894bf6542bf33625a52c0
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-11-12 (Fri, 12 Nov 2021)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/min-legal-vector-width.ll
    M llvm/test/CodeGen/X86/srem-seteq-vec-nonsplat.ll
    M llvm/test/CodeGen/X86/vector-fshl-256.ll
    M llvm/test/CodeGen/X86/vector-fshl-512.ll
    M llvm/test/CodeGen/X86/vector-fshl-rot-256.ll
    M llvm/test/CodeGen/X86/vector-fshl-rot-512.ll
    M llvm/test/CodeGen/X86/vector-fshr-256.ll
    M llvm/test/CodeGen/X86/vector-fshr-512.ll
    M llvm/test/CodeGen/X86/vector-fshr-rot-256.ll
    M llvm/test/CodeGen/X86/vector-fshr-rot-512.ll
    M llvm/test/CodeGen/X86/vector-rotate-256.ll
    M llvm/test/CodeGen/X86/vector-rotate-512.ll
    M llvm/test/CodeGen/X86/vector-shift-shl-256.ll
    M llvm/test/CodeGen/X86/vector-shift-shl-512.ll

  Log Message:
  -----------
  [X86] convertShiftLeftToScale - improve vXi8 constant handling

Add support for v32i8/v64i8 converting shift-by-constant to multiply-by-constant. This helps us avoid the generic vXi8 shift lowering, and a lot of VPBLENDVB ops which can be particularly slow.

We also needed to reorder a few shift lowering patterns to prevent regressions, particularly for XOP+AVX2 (Excavator) targets (which can split to fast v16i8 shifts) and AVX512-BWI targets (which prefers to extend to fast v32i16 shifts).