[HLSL] Collect explicit resource binding information (#111203)

Scans each global variable declaration and its members and collects all
required resource bindings in a new `SemaHLSL` data member `Bindings`.

New fields are added `HLSLResourceBindingAttr` for storing processed
binding information so that it can be used by CodeGen (`Bindings` or any
other Sema information is not accessible from CodeGen.)

Adjusts the existing register binding attribute handling and diagnostics
to:
- do not create HLSLResourceBindingAttribute if it is not valid
- diagnose only the simple/local errors when a register binding
attribute is parsed
- additional diagnostic of binding type mismatches is done later and
uses the new `Bindings` data

Fixes #110719

Author: hekota

clang/include/clang/Basic/Attr.td

@@ -4593,6 +4593,31 @@ def HLSLResourceBinding: InheritableAttr {
   let LangOpts = [HLSL];
   let Args = [StringArgument<"Slot">, StringArgument<"Space", 1>];
   let Documentation = [HLSLResourceBindingDocs];
+  let AdditionalMembers = [{
+  public:
+      enum class RegisterType : unsigned { SRV, UAV, CBuffer, Sampler, C, I };
+  
+  private:
+      RegisterType RegType;
+      unsigned SlotNumber;
+      unsigned SpaceNumber;
+
+  public:
+      void setBinding(RegisterType RT, unsigned SlotNum, unsigned SpaceNum) {
+        RegType = RT;
+        SlotNumber = SlotNum;
+        SpaceNumber = SpaceNum;
+      }
+      RegisterType getRegisterType() const {
+        return RegType;
+      }
+      unsigned getSlotNumber() const {
+        return SlotNumber;
+      }
+      unsigned getSpaceNumber() const {
+        return SpaceNumber;
+      }
+  }];
 }
 
 def HLSLPackOffset: HLSLAnnotationAttr {

clang/include/clang/Sema/SemaHLSL.h

@@ -28,13 +28,60 @@ class AttributeCommonInfo;
 class IdentifierInfo;
 class ParsedAttr;
 class Scope;
+class VarDecl;
+
+using llvm::dxil::ResourceClass;
 
 // FIXME: This can be hidden (as static function in SemaHLSL.cpp) once we no
 // longer need to create builtin buffer types in HLSLExternalSemaSource.
 bool CreateHLSLAttributedResourceType(
     Sema &S, QualType Wrapped, ArrayRef<const Attr *> AttrList,
     QualType &ResType, HLSLAttributedResourceLocInfo *LocInfo = nullptr);
 
+enum class BindingType : uint8_t { NotAssigned, Explicit, Implicit };
+
+// DeclBindingInfo struct stores information about required/assigned resource
+// binding onon a declaration for specific resource class.
+struct DeclBindingInfo {
+  const VarDecl *Decl;
+  ResourceClass ResClass;
+  const HLSLResourceBindingAttr *Attr;
+  BindingType BindType;
+
+  DeclBindingInfo(const VarDecl *Decl, ResourceClass ResClass,
+                  BindingType BindType = BindingType::NotAssigned,
+                  const HLSLResourceBindingAttr *Attr = nullptr)
+      : Decl(Decl), ResClass(ResClass), Attr(Attr), BindType(BindType) {}
+
+  void setBindingAttribute(HLSLResourceBindingAttr *A, BindingType BT) {
+    assert(Attr == nullptr && BindType == BindingType::NotAssigned &&
+           "binding attribute already assigned");
+    Attr = A;
+    BindType = BT;
+  }
+};
+
+// ResourceBindings class stores information about all resource bindings
+// in a shader. It is used for binding diagnostics and implicit binding
+// assigments.
+class ResourceBindings {
+public:
+  DeclBindingInfo *addDeclBindingInfo(const VarDecl *VD,
+                                      ResourceClass ResClass);
+  DeclBindingInfo *getDeclBindingInfo(const VarDecl *VD,
+                                      ResourceClass ResClass);
+  bool hasBindingInfoForDecl(const VarDecl *VD) const;
+
+private:
+  // List of all resource bindings required by the shader.
+  // A global declaration can have multiple bindings for different
+  // resource classes. They are all stored sequentially in this list.
+  // The DeclToBindingListIndex hashtable maps a declaration to the
+  // index of the first binding info in the list.
+  llvm::SmallVector<DeclBindingInfo> BindingsList;
+  llvm::DenseMap<const VarDecl *, unsigned> DeclToBindingListIndex;
+};
+
 class SemaHLSL : public SemaBase {
 public:
   SemaHLSL(Sema &S);
@@ -55,6 +102,7 @@ class SemaHLSL : public SemaBase {
   mergeParamModifierAttr(Decl *D, const AttributeCommonInfo &AL,
                          HLSLParamModifierAttr::Spelling Spelling);
   void ActOnTopLevelFunction(FunctionDecl *FD);
+  void ActOnVariableDeclarator(VarDecl *VD);
   void CheckEntryPoint(FunctionDecl *FD);
   void CheckSemanticAnnotation(FunctionDecl *EntryPoint, const Decl *Param,
                                const HLSLAnnotationAttr *AnnotationAttr);
@@ -102,6 +150,15 @@ class SemaHLSL : public SemaBase {
   llvm::DenseMap<const HLSLAttributedResourceType *,
                  HLSLAttributedResourceLocInfo>
       LocsForHLSLAttributedResources;
+
+  // List of all resource bindings
+  ResourceBindings Bindings;
+
+private:
+  void collectResourcesOnVarDecl(VarDecl *D);
+  void collectResourcesOnUserRecordDecl(const VarDecl *VD,
+                                        const RecordType *RT);
+  void processExplicitBindingsOnDecl(VarDecl *D);
 };
 
 } // namespace clang

clang/lib/Sema/SemaDecl.cpp

@@ -7883,6 +7883,9 @@ NamedDecl *Sema::ActOnVariableDeclarator(
   // Handle attributes prior to checking for duplicates in MergeVarDecl
   ProcessDeclAttributes(S, NewVD, D);
 
+  if (getLangOpts().HLSL)
+    HLSL().ActOnVariableDeclarator(NewVD);
+
   // FIXME: This is probably the wrong location to be doing this and we should
   // probably be doing this for more attributes (especially for function
   // pointer attributes such as format, warn_unused_result, etc.). Ideally