[llvm] Metadata: Optimize metadata queries (PR #70700)

[Jeremy Morse via llvm-commits]

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@@ -1620,10 +1629,7 @@ void Instruction::setNoSanitizeMetadata() {
 }
 
 MDNode *Instruction::getMetadataImpl(unsigned KindID) const {
-  // Handle 'dbg' as a special case since it is not stored in the hash table.
-  if (KindID == LLVMContext::MD_dbg)
-    return DbgLoc.getAsMDNode();
-  return Value::getMetadata(KindID);
+  return getValueMetadata(*this, KindID, getContext());
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jmorse wrote:

Could you leave a comment here indicting the assumptions of this method (non-'dbg', already checked metadata is present), it'll make it easier for those who aren't familiar with the Metadata hierarchy to understand what's going on.

https://github.com/llvm/llvm-project/pull/70700