[llvm] [TBAA] Recover !tbaa for a memcpy of struct with same type fields (PR #214116)

[Abhay Kanhere via llvm-commits]

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@@ -748,6 +748,35 @@ MDNode *AAMDNodes::shiftTBAA(MDNode *MD, size_t Offset) {
   return MD;
 }
 
+// Read a !tbaa.struct field entry (an offset or a size) into Out as a 64-bit
+// value. Returns false if it is not a constant integer that fits in 64 bits.
+static bool getTBAAStructFieldAsInt64(const MDOperand &Op, uint64_t &Out) {
+  auto *CI = mdconst::dyn_extract_or_null<ConstantInt>(Op);
+  if (!CI)
+    return false;
+  std::optional<uint64_t> Val = CI->getValue().tryZExtValue();
+  if (!Val)
+    return false;
+  Out = *Val;
+  return true;
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AbhayKanhere wrote:

yes looks like it. fixed.

https://github.com/llvm/llvm-project/pull/214116