[llvm] [AMDGPU] Enable vectorization of i8 values. (PR #134934)

[Shilei Tian via llvm-commits]

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@@ -1907,6 +1907,10 @@ class TargetTransformInfo {
   /// pad to. Default is no padding.
   unsigned getNumBytesToPadGlobalArray(unsigned Size, Type *ArrayType) const;
 
+  /// \return Returns true if vectorizing 4 x i8s into an i32 is possible.
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shiltian wrote:

```suggestion
  /// \return true if vectorizing 4 x i8s into an i32 is possible.
```

https://github.com/llvm/llvm-project/pull/134934