[llvm] [DirectX] Use an allow-list of DXIL compatible module metadata (PR #165290)

[Joshua Batista via llvm-commits]

================
@@ -426,19 +436,17 @@ static void translateGlobalMetadata(Module &M, DXILResourceMap &DRM,
 
   cleanModuleFlags(M);
 
-  // dx.rootsignatures will have been parsed from its metadata form as its
-  // binary form as part of the RootSignatureAnalysisWrapper, so safely
-  // remove it as it is not recognized in DXIL
-  if (NamedMDNode *RootSignature = M.getNamedMetadata("dx.rootsignatures"))
-    RootSignature->eraseFromParent();
-
-  // llvm.errno.tbaa was recently added but is not supported in LLVM 3.7 and
-  // causes all tests using the DXIL Validator to fail.
-  //
-  // This is a temporary fix and should be replaced with a allowlist once
-  // we have determined all metadata that the DXIL Validator allows
-  if (NamedMDNode *ErrNo = M.getNamedMetadata("llvm.errno.tbaa"))
-    ErrNo->eraseFromParent();
+  // Finally, strip all module metadata that is not explicitly specified in the
+  // allow-list
+  SmallVector<NamedMDNode *> ToStrip;
+
+  for (NamedMDNode &NamedMD : M.named_metadata())
+    if (!NamedMD.getName().starts_with("llvm.dbg.") &&
+        !llvm::is_contained(CompatibleNamedModuleMDs, NamedMD.getName()))
+      ToStrip.push_back(&NamedMD);
----------------
bob80905 wrote:

nit: Is the reason you don't erasefromparent right here because the for loop's iteration would skip over the next node?
I vaguely recall an std:: function that enabled deletion within a for loop without needing to make a separate list. 

https://github.com/llvm/llvm-project/pull/165290