[clang] [CIR] Compute union base subobject for tail-padding reuse (PR #201428)

[Erich Keane via cfe-commits]

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@@ -870,8 +888,20 @@ void CIRRecordLowering::lowerUnion() {
 
   if (layoutSize < getSize(storageType))
     storageType = getByteArrayType(layoutSize);
-  else
+
+  if (nonVirtualBaseType) {
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erichkeane wrote:

This is also quite different than classic codegen.  Why does it not need to calculate the padding here?

https://github.com/llvm/llvm-project/pull/201428