Add LayoutStruct to HLSLBufferDecl; add skipping of implicit initializers

Author: hekota

clang/include/clang/AST/Decl.h

@@ -5035,6 +5035,8 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
   /// HasValidPackoffset - Whether the buffer has valid packoffset annotations
   //                       on all declarations
   bool HasPackoffset;
+  // LayoutStruct - Layout struct for the buffer
+  CXXRecordDecl *LayoutStruct;
 
   HLSLBufferDecl(DeclContext *DC, bool CBuffer, SourceLocation KwLoc,
                  IdentifierInfo *ID, SourceLocation IDLoc,
@@ -5057,7 +5059,8 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
   bool isCBuffer() const { return IsCBuffer; }
   void setHasPackoffset(bool PO) { HasPackoffset = PO; }
   bool hasPackoffset() const { return HasPackoffset; }
-  const CXXRecordDecl *getLayoutStruct() const;
+  const CXXRecordDecl *getLayoutStruct() const { return LayoutStruct; }
+  void addLayoutStruct(CXXRecordDecl *LS);
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }

clang/lib/AST/Decl.cpp

@@ -5717,7 +5717,7 @@ HLSLBufferDecl::HLSLBufferDecl(DeclContext *DC, bool CBuffer,
                                SourceLocation IDLoc, SourceLocation LBrace)
     : NamedDecl(Decl::Kind::HLSLBuffer, DC, IDLoc, DeclarationName(ID)),
       DeclContext(Decl::Kind::HLSLBuffer), LBraceLoc(LBrace), KwLoc(KwLoc),
-      IsCBuffer(CBuffer), HasPackoffset(false) {}
+      IsCBuffer(CBuffer), HasPackoffset(false), LayoutStruct(nullptr) {}
 
 HLSLBufferDecl *HLSLBufferDecl::Create(ASTContext &C,
                                        DeclContext *LexicalParent, bool CBuffer,
@@ -5747,15 +5747,10 @@ HLSLBufferDecl *HLSLBufferDecl::CreateDeserialized(ASTContext &C,
                                     SourceLocation(), SourceLocation());
 }
 
-const CXXRecordDecl *HLSLBufferDecl::getLayoutStruct() const {
-  // Layout struct is the last decl in the HLSLBufferDecl.
-  if (CXXRecordDecl *RD = llvm::dyn_cast_or_null<CXXRecordDecl>(LastDecl)) {
-    assert(RD->getName().starts_with(
-               ("__cblayout_" + getIdentifier()->getName()).str()) &&
-           "expected buffer layout struct");
-    return RD;
-  }
-  llvm_unreachable("HLSL buffer is missing a layout struct");
+void HLSLBufferDecl::addLayoutStruct(CXXRecordDecl *LS) {
+  assert(LayoutStruct == nullptr && "layout struct has already been set");
+  LayoutStruct = LS;
+  addDecl(LS);
 }
 
 //===----------------------------------------------------------------------===//

clang/lib/Sema/SemaDecl.cpp

@@ -14184,6 +14184,12 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
         Var->getType().getAddressSpace() == LangAS::opencl_local)
       return;
 
+    // In HLSL, objects in the hlsl_constant address space are initialized
+    // externally, so don't synthesize an implicit initializer.
+    if (getLangOpts().HLSL &&
+        Var->getType().getAddressSpace() == LangAS::hlsl_constant)
+      return;
+
     // C++03 [dcl.init]p9:
     //   If no initializer is specified for an object, and the
     //   object is of (possibly cv-qualified) non-POD class type (or

clang/lib/Sema/SemaHLSL.cpp

@@ -502,7 +502,7 @@ void createHostLayoutStructForBuffer(Sema &S, HLSLBufferDecl *BufDecl) {
     }
   }
   LS->completeDefinition();
-  BufDecl->addDecl(LS);
+  BufDecl->addLayoutStruct(LS);
 }
 
 // Handle end of cbuffer/tbuffer declaration