[all-commits] [llvm/llvm-project] 16d1a6: [DirectX] Fix HLSL bitshifts to leverage the OpenC...

[Cooper Partin via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 16d1a6486c25769d264a6ddb70a48bbb1c23c077
      https://github.com/llvm/llvm-project/commit/16d1a6486c25769d264a6ddb70a48bbb1c23c077
  Author: Cooper Partin <coopp at microsoft.com>
  Date:   2024-02-08 (Thu, 08 Feb 2024)

  Changed paths:
    M clang/lib/CodeGen/CGExprScalar.cpp
    A clang/test/CodeGenHLSL/shift-mask.hlsl

  Log Message:
  -----------
  [DirectX] Fix HLSL bitshifts to leverage the OpenCL pipeline for bitshifting (#81030)

Fixes #55106

In HLSL bit shifts are defined to shift by shift size % type size. This
contains the following changes:

HLSL codegen bit shifts will be emitted as x << (y & (sizeof(x) - 1) and
bitshift masking leverages the OpenCL pipeline for this.

Tests were also added to validate this behavior.


Before this change the following was being emitted:
; Function Attrs: noinline nounwind optnone
define noundef i32 @"?shl32@@YAHHH at Z"(i32 noundef %V, i32 noundef %S) #0
{
entry:
  %S.addr = alloca i32, align 4
  %V.addr = alloca i32, align 4
  store i32 %S, ptr %S.addr, align 4
  store i32 %V, ptr %V.addr, align 4
  %0 = load i32, ptr %V.addr, align 4
  %1 = load i32, ptr %S.addr, align 4
  %shl = shl i32 %0, %1
  ret i32 %shl
}

After this change:
; Function Attrs: noinline nounwind optnone
define noundef i32 @"?shl32@@YAHHH at Z"(i32 noundef %V, i32 noundef %S) #0
{
entry:
  %S.addr = alloca i32, align 4
  %V.addr = alloca i32, align 4
  store i32 %S, ptr %S.addr, align 4
  store i32 %V, ptr %V.addr, align 4
  %0 = load i32, ptr %V.addr, align 4
  %1 = load i32, ptr %S.addr, align 4
  %shl.mask = and i32 %1, 31
  %shl = shl i32 %0, %shl.mask
  ret i32 %shl
}

---------

Co-authored-by: Cooper Partin <coopp at ntdev.microsoft.com>