[llvm-branch-commits] [clang] [llvm] [HLSL][DirectX] Add support for `rootsig` as a target environment (PR #156373)

[Justin Bogner via llvm-branch-commits]

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@@ -1472,5 +1473,38 @@ IdentifierInfo *ParseHLSLRootSignature(Sema &Actions,
   return DeclIdent;
 }
 
+void HandleRootSignatureTarget(Sema &S, StringRef EntryRootSig) {
+  ASTConsumer *Consumer = &S.getASTConsumer();
+
+  // Minimally initalize the parser. This does a couple things:
+  // - initializes Sema scope handling
+  // - invokes HLSLExternalSemaSource
+  // - invokes the preprocessor to lex the macros in the file
+  std::unique_ptr<Parser> P(new Parser(S.getPreprocessor(), S, true));
+  S.getPreprocessor().EnterMainSourceFile();
+
+  bool HaveLexer = S.getPreprocessor().getCurrentLexer();
+  if (HaveLexer) {
+    P->Initialize();
+    S.ActOnStartOfTranslationUnit();
+
+    // Skim through the file to parse to find the define
+    while (P->getCurToken().getKind() != tok::eof)
+      P->ConsumeAnyToken();
+
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bogner wrote:

I don't think we can remove `-finclude-default-header` because that may cause the input file to have parse errors, which could impede finding the define. I agree that consuming the file seems necessary here.

https://github.com/llvm/llvm-project/pull/156373