[llvm] [DebugInfo] Add DILayerLoc/DILayerLocList and DILocation irlayers operand (PR #215666)

[Stephen Tozer via llvm-commits]

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@@ -1472,8 +1472,12 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
     break;
   }
   case bitc::METADATA_LOCATION: {
-    // 5: inlinedAt, 6: isImplicit, 8: Key Instructions fields.
-    if (Record.size() != 5 && Record.size() != 6 && Record.size() != 8)
+    // Defined shapes: 5 (through inlinedAt), 6 (isImplicit), 8 (adds the Key
+    // Instructions fields), 9 (adds irlayers). Anything longer is a record from
+    // a newer writer and its trailing fields are ignored, which is what makes
+    // this encoding append-only; anything shorter, or a 7 (an atomGroup with no
+    // atomRank), is a shape no writer produces.
+    if (Record.size() < 5 || Record.size() == 7)
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SLTozer wrote:

It seems like this should also reject `Record.size() > 9` too?

https://github.com/llvm/llvm-project/pull/215666