[HLSL] Implement default constant buffer $Globals

clang/include/clang/AST/Decl.h

@@ -5032,6 +5032,16 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
   SourceLocation KwLoc;
   /// IsCBuffer - Whether the buffer is a cbuffer (and not a tbuffer).
   bool IsCBuffer;
+  /// HasValidPackoffset - Whether the buffer has valid packoffset annotations
+  //                       on all declarations
+  bool HasPackoffset;
+  // LayoutStruct - Layout struct for the buffer
+  CXXRecordDecl *LayoutStruct;
+
+  // For default (implicit) constant buffer, a lisf of references of global
+  // decls that belong to the buffer. The decls are already parented by the
+  // translation unit context.
+  SmallVector<Decl *> DefaultBufferDecls;
 
   HLSLBufferDecl(DeclContext *DC, bool CBuffer, SourceLocation KwLoc,
                  IdentifierInfo *ID, SourceLocation IDLoc,
@@ -5042,6 +5052,8 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
                                 bool CBuffer, SourceLocation KwLoc,
                                 IdentifierInfo *ID, SourceLocation IDLoc,
                                 SourceLocation LBrace);
+  static HLSLBufferDecl *CreateDefaultCBuffer(ASTContext &C,
+                                              DeclContext *LexicalParent);
   static HLSLBufferDecl *CreateDeserialized(ASTContext &C, GlobalDeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY {
@@ -5052,6 +5064,11 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
   SourceLocation getRBraceLoc() const { return RBraceLoc; }
   void setRBraceLoc(SourceLocation L) { RBraceLoc = L; }
   bool isCBuffer() const { return IsCBuffer; }
+  void setHasPackoffset(bool PO) { HasPackoffset = PO; }
+  bool hasPackoffset() const { return HasPackoffset; }
+  const CXXRecordDecl *getLayoutStruct() const { return LayoutStruct; }
+  void addLayoutStruct(CXXRecordDecl *LS);
+  void addDefaultBufferDecl(Decl *D);
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
@@ -5063,6 +5080,20 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
     return static_cast<HLSLBufferDecl *>(const_cast<DeclContext *>(DC));
   }
 
+  // Iterator for the buffer decls. Concatenates the list of decls parented
+  // by this HLSLBufferDecl with the list of default buffer decls.
+  using buffer_decl_iterator =
+      llvm::concat_iterator<Decl *const, SmallVector<Decl *>::const_iterator,
+                            decl_iterator>;
+  using buffer_decl_range = llvm::iterator_range<buffer_decl_iterator>;
+
+  buffer_decl_range buffer_decls() const {
+    return buffer_decl_range(buffer_decls_begin(), buffer_decls_end());
+  }
+  buffer_decl_iterator buffer_decls_begin() const;
+  buffer_decl_iterator buffer_decls_end() const;
+  bool buffer_decls_empty();
+
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
 };

clang/include/clang/AST/Type.h

@@ -6266,8 +6266,8 @@ class HLSLAttributedResourceType : public Type, public llvm::FoldingSetNode {
     LLVM_PREFERRED_TYPE(bool)
     uint8_t RawBuffer : 1;
 
-    Attributes(llvm::dxil::ResourceClass ResourceClass, bool IsROV,
-               bool RawBuffer)
+    Attributes(llvm::dxil::ResourceClass ResourceClass, bool IsROV = false,
+               bool RawBuffer = false)
         : ResourceClass(ResourceClass), IsROV(IsROV), RawBuffer(RawBuffer) {}
 
     Attributes() : Attributes(llvm::dxil::ResourceClass::UAV, false, false) {}

clang/include/clang/Sema/SemaHLSL.h

@@ -103,13 +103,13 @@ class SemaHLSL : public SemaBase {
                          HLSLParamModifierAttr::Spelling Spelling);
   void ActOnTopLevelFunction(FunctionDecl *FD);
   void ActOnVariableDeclarator(VarDecl *VD);
+  void ActOnEndOfTranslationUnit(TranslationUnitDecl *TU);
   void CheckEntryPoint(FunctionDecl *FD);
   void CheckSemanticAnnotation(FunctionDecl *EntryPoint, const Decl *Param,
                                const HLSLAnnotationAttr *AnnotationAttr);
   void DiagnoseAttrStageMismatch(
       const Attr *A, llvm::Triple::EnvironmentType Stage,
       std::initializer_list<llvm::Triple::EnvironmentType> AllowedStages);
-  void DiagnoseAvailabilityViolations(TranslationUnitDecl *TU);
 
   QualType handleVectorBinOpConversion(ExprResult &LHS, ExprResult &RHS,
                                        QualType LHSType, QualType RHSType,
@@ -159,11 +159,16 @@ class SemaHLSL : public SemaBase {
   // List of all resource bindings
   ResourceBindings Bindings;
 
+  // default constant buffer $Globals
+  HLSLBufferDecl *DefaultCBuffer;
+
 private:
   void collectResourcesOnVarDecl(VarDecl *D);
   void collectResourcesOnUserRecordDecl(const VarDecl *VD,
                                         const RecordType *RT);
   void processExplicitBindingsOnDecl(VarDecl *D);
+
+  void diagnoseAvailabilityViolations(TranslationUnitDecl *TU);
 };
 
 } // namespace clang

clang/lib/AST/Decl.cpp

@@ -57,6 +57,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
@@ -1747,6 +1748,10 @@ void NamedDecl::printNestedNameSpecifier(raw_ostream &OS,
       }
     }
 
+    // Suppress transparent contexts like export or HLSLBufferDecl context
+    if (Ctx->isTransparentContext())
+      continue;
+
     // Skip non-named contexts such as linkage specifications and ExportDecls.
     const NamedDecl *ND = dyn_cast<NamedDecl>(Ctx);
     if (!ND)
@@ -5713,7 +5718,7 @@ 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) {}
+      IsCBuffer(CBuffer), HasPackoffset(false), LayoutStruct(nullptr) {}
 
 HLSLBufferDecl *HLSLBufferDecl::Create(ASTContext &C,
                                        DeclContext *LexicalParent, bool CBuffer,
@@ -5737,12 +5742,53 @@ HLSLBufferDecl *HLSLBufferDecl::Create(ASTContext &C,
   return Result;
 }
 
+HLSLBufferDecl *
+HLSLBufferDecl::CreateDefaultCBuffer(ASTContext &C,
+                                     DeclContext *LexicalParent) {
+  DeclContext *DC = LexicalParent;
+  IdentifierInfo *II = &C.Idents.get("$Globals", tok::TokenKind::identifier);
+  HLSLBufferDecl *Result = new (C, DC) HLSLBufferDecl(
+      DC, true, SourceLocation(), II, SourceLocation(), SourceLocation());
+  Result->setImplicit(true);
+  return Result;
+}
+
 HLSLBufferDecl *HLSLBufferDecl::CreateDeserialized(ASTContext &C,
                                                    GlobalDeclID ID) {
   return new (C, ID) HLSLBufferDecl(nullptr, false, SourceLocation(), nullptr,
                                     SourceLocation(), SourceLocation());
 }
 
+void HLSLBufferDecl::addLayoutStruct(CXXRecordDecl *LS) {
+  assert(LayoutStruct == nullptr && "layout struct has already been set");
+  LayoutStruct = LS;
+  addDecl(LS);
+}
+
+void HLSLBufferDecl::addDefaultBufferDecl(Decl *D) {
+  assert(isImplicit() &&
+         "default decls can only be added to the implicit/default constant "
+         "buffer $Globals");
+  DefaultBufferDecls.push_back(D);
+}
+
+HLSLBufferDecl::buffer_decl_iterator
+HLSLBufferDecl::buffer_decls_begin() const {
+  return buffer_decl_iterator(llvm::iterator_range(DefaultBufferDecls.begin(),
+                                                   DefaultBufferDecls.end()),
+                              decl_range(decls_begin(), decls_end()));
+}
+
+HLSLBufferDecl::buffer_decl_iterator HLSLBufferDecl::buffer_decls_end() const {
+  return buffer_decl_iterator(
+      llvm::iterator_range(DefaultBufferDecls.end(), DefaultBufferDecls.end()),
+      decl_range(decls_end(), decls_end()));
+}
+
+bool HLSLBufferDecl::buffer_decls_empty() {
+  return DefaultBufferDecls.empty() && decls_empty();
+}
+
 //===----------------------------------------------------------------------===//
 // ImportDecl Implementation
 //===----------------------------------------------------------------------===//