code review feedback - update comment, add new line

Author: hekota

clang/include/clang/AST/Decl.h

@@ -5087,8 +5087,16 @@ 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.
+  // Iterator for the buffer decls. For constant buffers explicitly declared
+  // with `cbuffer` keyword this will the list of decls parented by this
+  // HLSLBufferDecl (equal to `decls()`).
+  // For implicit $Globals buffer this will be the list of default buffer
+  // declarations stored in DefaultBufferDecls plus the implicit layout
+  // struct (the only child of HLSLBufferDecl in this case).
+  //
+  // The iterator uses llvm::concat_iterator to concatenate the lists
+  // `decls()` and `DefaultBufferDecls`. For non-default buffers
+  // `DefaultBufferDecls` is always empty.
   using buffer_decl_iterator =
       llvm::concat_iterator<Decl *const, SmallVector<Decl *>::const_iterator,
                             decl_iterator>;

clang/lib/CodeGen/CGHLSLRuntime.cpp

@@ -150,6 +150,7 @@ void CGHLSLRuntime::emitBufferGlobalsAndMetadata(const HLSLBufferDecl *BufDecl,
     llvm::Type *LayoutType = *ElemIt++;
 
     // FIXME: handle resources in cbuffer user-defined structs
+    // Issue llvm/wg-hlsl#175
 
     // create global variable for the constant and to metadata list
     GlobalVariable *ElemGV =

clang/test/CodeGenHLSL/default_cbuffer.hlsl

@@ -36,4 +36,4 @@ void main() {
 }
 
 // CHECK: !hlsl.cbs = !{![[CB:.*]]}
-// CHECK: ![[CB]] = !{ptr @"$Globals.cb", ptr addrspace(2) @a, ptr addrspace(2) @g, ptr addrspace(2) @h}
+// CHECK: ![[CB]] = !{ptr @"$Globals.cb", ptr addrspace(2) @a, ptr addrspace(2) @g, ptr addrspace(2) @h}