1 files changed, 32 insertions, 3 deletions
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.h b/clang/lib/CodeGen/CGHLSLRuntime.h
index 9d31714..488a322 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.h
+++ b/clang/lib/CodeGen/CGHLSLRuntime.h
@@ -81,6 +81,33 @@ class CodeGenModule;
 class CodeGenFunction;
 class LValue;
 
+class CGHLSLOffsetInfo {
+  SmallVector<uint32_t> Offsets;
+
+public:
+  static const uint32_t Unspecified = ~0U;
+
+  /// Iterates over all declarations in the HLSL buffer and based on the
+  /// packoffset or register(c#) annotations it fills outs the Offsets vector
+  /// with the user-specified layout offsets. The buffer offsets can be
+  /// specified 2 ways: 1. declarations in cbuffer {} block can have a
+  /// packoffset annotation (translates to HLSLPackOffsetAttr) 2. default
+  /// constant buffer declarations at global scope can have register(c#)
+  /// annotations (translates to HLSLResourceBindingAttr with RegisterType::C)
+  /// It is not guaranteed that all declarations in a buffer have an annotation.
+  /// For those where it is not specified a `~0U` value is added to the Offsets
+  /// vector. In the final layout these declarations will be placed at the end
+  /// of the HLSL buffer after all of the elements with specified offset.
+  static CGHLSLOffsetInfo fromDecl(const HLSLBufferDecl &BufDecl);
+
+  /// Get the given offset, or `~0U` if there is no offset for the member.
+  uint32_t operator[](size_t I) const {
+    if (Offsets.empty())
+      return Unspecified;
+    return Offsets[I];
+  }
+};
+
 class CGHLSLRuntime {
 public:
   //===----------------------------------------------------------------------===//
@@ -167,9 +194,11 @@ public:
   CGHLSLRuntime(CodeGenModule &CGM) : CGM(CGM) {}
   virtual ~CGHLSLRuntime() {}
 
-  llvm::Type *
-  convertHLSLSpecificType(const Type *T,
-                          SmallVector<int32_t> *Packoffsets = nullptr);
+  llvm::Type *convertHLSLSpecificType(const Type *T,
+                                      const CGHLSLOffsetInfo &OffsetInfo);
+  llvm::Type *convertHLSLSpecificType(const Type *T) {
+    return convertHLSLSpecificType(T, CGHLSLOffsetInfo());
+  }
 
   void generateGlobalCtorDtorCalls();