[llvm] [DebugInfo][RemoveDIs] Use autoupgrader to convert old debug-info (PR #143452)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -4398,11 +4397,25 @@ static Value *upgradeAMDGCNIntrinsicCall(StringRef Name, CallBase *CI,
 /// Helper to unwrap intrinsic call MetadataAsValue operands.
 template <typename MDType>
 static MDType *unwrapMAVOp(CallBase *CI, unsigned Op) {
-  if (MetadataAsValue *MAV = dyn_cast<MetadataAsValue>(CI->getArgOperand(Op)))
-    return dyn_cast<MDType>(MAV->getMetadata());
+  if (Op < CI->arg_size()) {
+    if (MetadataAsValue *MAV = dyn_cast<MetadataAsValue>(CI->getArgOperand(Op)))
+      // Use a reinterpret cast rather than a safe default-to-null cast: the
+      // autoupgrade process happens before the verifier, and thus there might
+      // be some nonsense metadata in there.
+      return reinterpret_cast<MDType*>(MAV->getMetadata());
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OCHyams wrote:

nit: I think this comment could be simplified? Something like "Use reinterpret_cast rather than dyn_cast because the autoupgrade process happens before the verifier, meaning we may see unexpected operands here". YMMV. Also I think the style guide says to put braces around multi-line ifs (even if it's a comment making it multi-line).

https://github.com/llvm/llvm-project/pull/143452