[llvm] [AMDGPU] Extended vector promotion to aggregate types. (PR #143784)

[via llvm-commits]

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@@ -818,6 +818,28 @@ static BasicBlock::iterator skipToNonAllocaInsertPt(BasicBlock &BB,
   return I;
 }
 
+/// Get the underlying type of a homogeneous aggregate type, or nullptr if the
+/// type is non-homogeneous.
+static Type *getHomogeneousType(Type *Ty) {
+  if (auto *VectorTy = dyn_cast<FixedVectorType>(Ty))
+    return VectorTy->getElementType();
+  if (auto *ArrayTy = dyn_cast<ArrayType>(Ty))
+    return getHomogeneousType(ArrayTy->getElementType());
+  if (auto *StructTy = dyn_cast<StructType>(Ty)) {
+    if (StructTy->getNumElements() == 0)
+      return nullptr;
+
+    auto *Iter = StructTy->element_begin();
+    Type *HTy = getHomogeneousType(*Iter);
+    for (; Iter != StructTy->element_end(); ++Iter)
+      if (getHomogeneousType(*Iter) != HTy)
+        return nullptr;
+
+    return HTy;
+  }
+  return Ty;
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zGoldthorpe wrote:

For non-aggregate types, I figured `getHomogeneousType` should just return the type back. This won't affect the pass either way, though, since singletons won't get promoted to vectors anyway.

https://github.com/llvm/llvm-project/pull/143784