[all-commits] [llvm/llvm-project] a4124e: [X86] When storing v1i1/v2i1/v4i1 to memory, make ...

[Craig Topper via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: a4124e455e641db1e18d4221d2dacb31953fd13b
      https://github.com/llvm/llvm-project/commit/a4124e455e641db1e18d4221d2dacb31953fd13b
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2020-11-12 (Thu, 12 Nov 2020)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/lib/Target/X86/X86InstrAVX512.td
    M llvm/test/CodeGen/X86/avx512-extract-subvector-load-store.ll
    M llvm/test/CodeGen/X86/avx512-load-trunc-store-i1.ll
    M llvm/test/CodeGen/X86/avx512-mask-op.ll
    M llvm/test/CodeGen/X86/avx512-select.ll
    M llvm/test/CodeGen/X86/stack-folding-avx512vp2intersect.ll
    M llvm/test/CodeGen/X86/vec_saddo.ll
    M llvm/test/CodeGen/X86/vec_smulo.ll
    M llvm/test/CodeGen/X86/vec_ssubo.ll
    M llvm/test/CodeGen/X86/vec_uaddo.ll
    M llvm/test/CodeGen/X86/vec_umulo.ll
    M llvm/test/CodeGen/X86/vec_usubo.ll

  Log Message:
  -----------
  [X86] When storing v1i1/v2i1/v4i1 to memory, make sure we store zeros in the rest of the byte

We can't store garbage in the unused bits. It possible that something like zextload from i1/i2/i4 is created to read the memory. Those zextloads would be legalized assuming the extra bits are 0.

I'm not sure that the code in lowerStore is executed for the v1i1/v2i1/v4i1 case. It looks like the DAG combine in combineStore may have converted them to v8i1 first. And I think we're missing some cases to avoid going to the stack in the first place. But I don't have time to investigate those things at the moment so I wanted to focus on the correctness issue.

Should fix PR48147.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D91294