[Frontend][HLSL] Define HLSLFrontendAction to add a PPCallback

Author: inbelic

clang/include/clang/HLSL/Frontend/FrontendActions.h

@@ -0,0 +1,26 @@
+//===- HLSL/FrontendActions.h -----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_HLSL_FRONTEND_ACTIONS_H
+#define LLVM_CLANG_HLSL_FRONTEND_ACTIONS_H
+
+#include "clang/Frontend/FrontendAction.h"
+
+namespace clang {
+
+class HLSLFrontendAction : public WrapperFrontendAction {
+protected:
+  void ExecuteAction() override;
+
+public:
+  HLSLFrontendAction(std::unique_ptr<FrontendAction> WrappedAction);
+};
+
+} // namespace clang
+
+#endif // LLVM_CLANG_HLSL_FRONTEND_ACTIONS_H

clang/lib/CodeGen/CodeGenModule.cpp

@@ -7534,6 +7534,9 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
             getContext().getCanonicalTagType(cast<EnumDecl>(D)));
     break;
 
+    // Will be handled by attached function
+  case Decl::HLSLRootSignature:
+    break;
   case Decl::HLSLBuffer:
     getHLSLRuntime().addBuffer(cast<HLSLBufferDecl>(D));
     break;

clang/lib/Frontend/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_subdirectory(Rewrite)
+add_subdirectory(HLSL)
 
 set(LLVM_LINK_COMPONENTS
   BitReader

clang/lib/Frontend/HLSL/CMakeLists.txt

@@ -0,0 +1,14 @@
+set(LLVM_LINK_COMPONENTS
+  Support
+  )
+
+add_clang_library(clangHLSLFrontend
+  FrontendActions.cpp
+
+  LINK_LIBS
+  clangAST
+  clangBasic
+  clangFrontend
+  clangParse
+  clangSema
+  )

clang/lib/Frontend/HLSL/FrontendActions.cpp

@@ -0,0 +1,92 @@
+//===--- FrontendActions.cpp ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/HLSL/Frontend/FrontendActions.h"
+#include "clang/Parse/ParseHLSLRootSignature.h"
+#include "clang/Sema/Sema.h"
+
+namespace clang {
+
+class InjectRootSignatureCallback : public PPCallbacks {
+private:
+  Sema &Actions;
+  StringRef RootSigName;
+  llvm::dxbc::RootSignatureVersion Version;
+
+  std::optional<StringLiteral *> processStringLiteral(ArrayRef<Token> Tokens) {
+    for (Token Tok : Tokens)
+      if (!tok::isStringLiteral(Tok.getKind()))
+        return std::nullopt;
+
+    ExprResult StringResult = Actions.ActOnUnevaluatedStringLiteral(Tokens);
+    if (StringResult.isInvalid())
+      return std::nullopt;
+
+    if (auto Signature = dyn_cast<StringLiteral>(StringResult.get()))
+      return Signature;
+
+    return std::nullopt;
+  }
+
+public:
+  void MacroDefined(const Token &MacroNameTok,
+                    const MacroDirective *MD) override {
+    if (RootSigName != MacroNameTok.getIdentifierInfo()->getName())
+      return;
+
+    const MacroInfo *MI = MD->getMacroInfo();
+    auto Signature = processStringLiteral(MI->tokens());
+    if (!Signature.has_value()) {
+      Actions.getDiagnostics().Report(MI->getDefinitionLoc(),
+                                      diag::err_expected_string_literal)
+          << /*in attributes...*/ 4 << "RootSignature";
+      return;
+    }
+
+    IdentifierInfo *DeclIdent =
+        hlsl::ParseHLSLRootSignature(Actions, Version, *Signature);
+  }
+
+  InjectRootSignatureCallback(Sema &Actions, StringRef RootSigName,
+                              llvm::dxbc::RootSignatureVersion Version)
+      : PPCallbacks(), Actions(Actions), RootSigName(RootSigName),
+        Version(Version) {}
+};
+
+void HLSLFrontendAction::ExecuteAction() {
+  // Pre-requisites to invoke
+  CompilerInstance &CI = getCompilerInstance();
+  if (!CI.hasASTContext() || !CI.hasPreprocessor())
+    return WrapperFrontendAction::ExecuteAction();
+
+  // InjectRootSignatureCallback requires access to invoke Sema to lookup/
+  // register a root signature declaration. The wrapped action is required to
+  // account for this by only creating a Sema if one doesn't already exist
+  // (like we have done, and, ASTFrontendAction::ExecuteAction)
+  if (!CI.hasSema())
+    CI.createSema(getTranslationUnitKind(),
+                  /*CodeCompleteConsumer=*/nullptr);
+  Sema &S = CI.getSema();
+
+  // Register HLSL specific callbacks
+  auto LangOpts = CI.getLangOpts();
+  auto MacroCallback = std::make_unique<InjectRootSignatureCallback>(
+      S, LangOpts.HLSLRootSigOverride, LangOpts.HLSLRootSigVer);
+
+  Preprocessor &PP = CI.getPreprocessor();
+  PP.addPPCallbacks(std::move(MacroCallback));
+
+  // Invoke as normal
+  WrapperFrontendAction::ExecuteAction();
+}
+
+HLSLFrontendAction::HLSLFrontendAction(
+    std::unique_ptr<FrontendAction> WrappedAction)
+    : WrapperFrontendAction(std::move(WrappedAction)) {}
+
+} // namespace clang

clang/lib/FrontendTool/CMakeLists.txt

@@ -10,6 +10,7 @@ set(link_libs
   clangExtractAPI
   clangFrontend
   clangRewriteFrontend
+  clangHLSLFrontend
   )
 
 set(deps)

clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp

@@ -22,6 +22,7 @@
 #include "clang/Frontend/FrontendPluginRegistry.h"
 #include "clang/Frontend/Utils.h"
 #include "clang/FrontendTool/Utils.h"
+#include "clang/HLSL/Frontend/FrontendActions.h"
 #include "clang/Rewrite/Frontend/FrontendActions.h"
 #include "clang/StaticAnalyzer/Frontend/AnalyzerHelpFlags.h"
 #include "clang/StaticAnalyzer/Frontend/FrontendActions.h"
@@ -181,6 +182,10 @@ CreateFrontendAction(CompilerInstance &CI) {
 
   const FrontendOptions &FEOpts = CI.getFrontendOpts();
 
+  if (CI.getLangOpts().HLSL) {
+    Act = std::make_unique<HLSLFrontendAction>(std::move(Act));
+  }
+
   if (FEOpts.FixAndRecompile) {
     Act = std::make_unique<FixItRecompile>(std::move(Act));
   }