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

[Helena Kotas via cfe-commits]

================
@@ -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);
+
+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;
----------------
hekota wrote:

Yeah. LLVM has `SparseMultiSet` class but it does not seem to be a good fit for our case:

*Fast multiset implementation for objects that can be identified by small unsigned keys.*
https://llvm.org/doxygen/classllvm_1_1SparseMultiSet.html

https://github.com/llvm/llvm-project/pull/111203