[llvm-branch-commits] [clang] [HLSL] Constant buffers codegen (PR #124886)

Helena Kotas via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Tue Feb 4 18:01:33 PST 2025


https://github.com/hekota updated https://github.com/llvm/llvm-project/pull/124886

>From cf08adb6b9e181613e81d2cfbadbbb68e645fe33 Mon Sep 17 00:00:00 2001
From: Helena Kotas <hekotas at microsoft.com>
Date: Tue, 28 Jan 2025 14:46:26 -0800
Subject: [PATCH 1/4] [HLSL] Translate cbuffer declarations to target type
 dx.CBuffer - initial commit

---
 clang/include/clang/AST/Decl.h                |   6 +
 clang/include/clang/AST/Type.h                |   4 +-
 clang/lib/AST/Decl.cpp                        |  17 +-
 clang/lib/CodeGen/CGHLSLRuntime.cpp           | 409 ++++++++++++------
 clang/lib/CodeGen/CGHLSLRuntime.h             |  31 +-
 clang/lib/CodeGen/Targets/DirectX.cpp         |  11 +-
 clang/lib/Sema/SemaHLSL.cpp                   |   3 +
 clang/test/CodeGenHLSL/cbuf.hlsl              |  33 --
 clang/test/CodeGenHLSL/cbuf_in_namespace.hlsl |  29 --
 clang/test/CodeGenHLSL/cbuffer.hlsl           | 200 +++++++++
 .../CodeGenHLSL/cbuffer_and_namespaces.hlsl   |  63 +++
 .../CodeGenHLSL/cbuffer_with_packoffset.hlsl  |  40 ++
 ...uffer_with_static_global_and_function.hlsl |  32 ++
 clang/test/CodeGenHLSL/resource-bindings.hlsl |   4 +
 .../static_global_and_function_in_cb.hlsl     |  22 -
 15 files changed, 679 insertions(+), 225 deletions(-)
 delete mode 100644 clang/test/CodeGenHLSL/cbuf.hlsl
 delete mode 100644 clang/test/CodeGenHLSL/cbuf_in_namespace.hlsl
 create mode 100644 clang/test/CodeGenHLSL/cbuffer.hlsl
 create mode 100644 clang/test/CodeGenHLSL/cbuffer_and_namespaces.hlsl
 create mode 100644 clang/test/CodeGenHLSL/cbuffer_with_packoffset.hlsl
 create mode 100644 clang/test/CodeGenHLSL/cbuffer_with_static_global_and_function.hlsl
 delete mode 100644 clang/test/CodeGenHLSL/static_global_and_function_in_cb.hlsl

diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index 16403774e72b31..e1c7e3817699ce 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -5032,6 +5032,9 @@ 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;
 
   HLSLBufferDecl(DeclContext *DC, bool CBuffer, SourceLocation KwLoc,
                  IdentifierInfo *ID, SourceLocation IDLoc,
@@ -5052,6 +5055,9 @@ 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;
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index 1d9743520654eb..c3ff7ebd88516c 100644
--- a/clang/include/clang/AST/Type.h
+++ b/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) {}
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index beb5fcaefac535..fa7d03354a9937 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1747,6 +1747,10 @@ 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 +5717,7 @@ 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) {}
 
 HLSLBufferDecl *HLSLBufferDecl::Create(ASTContext &C,
                                        DeclContext *LexicalParent, bool CBuffer,
@@ -5743,6 +5747,17 @@ HLSLBufferDecl *HLSLBufferDecl::CreateDeserialized(ASTContext &C,
                                     SourceLocation(), SourceLocation());
 }
 
+const CXXRecordDecl *HLSLBufferDecl::getLayoutStruct() const {
+  // Layout struct is the last decl in the HLSLBufferDecl.
+  if (CXXRecordDecl *RD = llvm::dyn_cast_or_null<CXXRecordDecl>(LastDecl)) {
+    assert(RD->getName().starts_with(
+               ("__cblayout_" + getIdentifier()->getName()).str()) &&
+           "expected buffer layout struct");
+    return RD;
+  }
+  llvm_unreachable("HLSL buffer is missing a layout struct");
+}
+
 //===----------------------------------------------------------------------===//
 // ImportDecl Implementation
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.cpp b/clang/lib/CodeGen/CGHLSLRuntime.cpp
index 2ce54cc3c52efa..d3d9d426643596 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -16,15 +16,20 @@
 #include "CGDebugInfo.h"
 #include "CodeGenModule.h"
 #include "TargetInfo.h"
+#include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/Type.h"
 #include "clang/Basic/TargetOptions.h"
+#include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
+#include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/Alignment.h"
 
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormatVariadic.h"
 
 using namespace clang;
@@ -32,6 +37,9 @@ using namespace CodeGen;
 using namespace clang::hlsl;
 using namespace llvm;
 
+static void createResourceInitFn(CodeGenModule &CGM, llvm::GlobalVariable *GV,
+                                 unsigned Slot, unsigned Space);
+
 namespace {
 
 void addDxilValVersion(StringRef ValVersionStr, llvm::Module &M) {
@@ -54,54 +62,11 @@ void addDxilValVersion(StringRef ValVersionStr, llvm::Module &M) {
   auto *DXILValMD = M.getOrInsertNamedMetadata(DXILValKey);
   DXILValMD->addOperand(Val);
 }
+
 void addDisableOptimizations(llvm::Module &M) {
   StringRef Key = "dx.disable_optimizations";
   M.addModuleFlag(llvm::Module::ModFlagBehavior::Override, Key, 1);
 }
-// cbuffer will be translated into global variable in special address space.
-// If translate into C,
-// cbuffer A {
-//   float a;
-//   float b;
-// }
-// float foo() { return a + b; }
-//
-// will be translated into
-//
-// struct A {
-//   float a;
-//   float b;
-// } cbuffer_A __attribute__((address_space(4)));
-// float foo() { return cbuffer_A.a + cbuffer_A.b; }
-//
-// layoutBuffer will create the struct A type.
-// replaceBuffer will replace use of global variable a and b with cbuffer_A.a
-// and cbuffer_A.b.
-//
-void layoutBuffer(CGHLSLRuntime::Buffer &Buf, const DataLayout &DL) {
-  if (Buf.Constants.empty())
-    return;
-
-  std::vector<llvm::Type *> EltTys;
-  for (auto &Const : Buf.Constants) {
-    GlobalVariable *GV = Const.first;
-    Const.second = EltTys.size();
-    llvm::Type *Ty = GV->getValueType();
-    EltTys.emplace_back(Ty);
-  }
-  Buf.LayoutStruct = llvm::StructType::get(EltTys[0]->getContext(), EltTys);
-}
-
-GlobalVariable *replaceBuffer(CGHLSLRuntime::Buffer &Buf) {
-  // Create global variable for CB.
-  GlobalVariable *CBGV = new GlobalVariable(
-      Buf.LayoutStruct, /*isConstant*/ true,
-      GlobalValue::LinkageTypes::ExternalLinkage, nullptr,
-      llvm::formatv("{0}{1}", Buf.Name, Buf.IsCBuffer ? ".cb." : ".tb."),
-      GlobalValue::NotThreadLocal);
-
-  return CBGV;
-}
 
 } // namespace
 
@@ -119,48 +84,280 @@ llvm::Triple::ArchType CGHLSLRuntime::getArch() {
   return CGM.getTarget().getTriple().getArch();
 }
 
-void CGHLSLRuntime::addConstant(VarDecl *D, Buffer &CB) {
-  if (D->getStorageClass() == SC_Static) {
-    // For static inside cbuffer, take as global static.
-    // Don't add to cbuffer.
-    CGM.EmitGlobal(D);
-    return;
+// Returns true if the type is an HLSL resource class
+static bool isResourceRecordType(const clang::Type *Ty) {
+  return HLSLAttributedResourceType::findHandleTypeOnResource(Ty) != nullptr;
+}
+
+// Returns true if the type is an HLSL resource class or an array of
+// HLSL resource classes
+static bool isResourceRecordTypeOrArrayOf(const clang::Type *Ty) {
+  while (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(Ty))
+    Ty = CAT->getArrayElementTypeNoTypeQual();
+  return isResourceRecordType(Ty);
+}
+
+static ConstantAsMetadata *getConstIntMetadata(LLVMContext &Ctx, uint32_t value,
+                                               bool isSigned = false) {
+  return ConstantAsMetadata::get(
+      ConstantInt::get(Ctx, llvm::APInt(32, value, isSigned)));
+}
+
+static unsigned getScalarOrVectorSize(llvm::Type *Ty) {
+  assert(Ty->isVectorTy() || Ty->isIntegerTy() || Ty->isFloatingPointTy());
+  if (Ty->isVectorTy()) {
+    llvm::FixedVectorType *FVT = cast<llvm::FixedVectorType>(Ty);
+    return FVT->getNumElements() *
+           (FVT->getElementType()->getScalarSizeInBits() / 8);
+  }
+  return Ty->getScalarSizeInBits() / 8;
+}
+
+size_t
+CGHLSLRuntime::getOrCalculateStructSizeForBuffer(llvm::StructType *StructTy) {
+  assert(StructTy->isStructTy());
+
+  // check if we already have a side for this struct
+  auto SizeIt = StructSizesForBuffer.find(StructTy);
+  if (SizeIt != StructSizesForBuffer.end())
+    return SizeIt->getSecond();
+
+  // if not, calculate the struct layout and add it to metadata
+  LLVMContext &Ctx = CGM.getLLVMContext();
+  SmallVector<llvm::Metadata *> LayoutItems;
+  LayoutItems.push_back(MDString::get(Ctx, StructTy->getName()));
+
+  size_t StructSize = 0;
+  LayoutItems.push_back(nullptr); // reserve one slot for the buffer size
+
+  for (llvm::Type *ElTy : StructTy->elements())
+    addLayoutInfoForBufferElement(StructSize, LayoutItems, ElTy);
+
+  // set the size of the buffer
+  LayoutItems[1] = getConstIntMetadata(Ctx, StructSize);
+
+  // add the struct layout info to metadata
+  MDNode *LayoutMDNode = MDNode::get(CGM.getLLVMContext(), LayoutItems);
+  CGM.getModule()
+      .getOrInsertNamedMetadata("hlsl.cblayouts")
+      ->addOperand(LayoutMDNode);
+
+  // add struct size to list and return it
+  StructSizesForBuffer[StructTy] = StructSize;
+  return StructSize;
+}
+
+void CGHLSLRuntime::addLayoutInfoForBufferElement(
+    size_t &EndOffset, SmallVector<llvm::Metadata *> &LayoutItems,
+    llvm::Type *LayoutTy, HLSLPackOffsetAttr *PackoffsetAttr) {
+
+  // calculate element offset and size; for arrays also calculate array
+  // element count and stride
+  size_t ElemOffset = 0;
+  size_t ElemSize = 0;
+  size_t ArrayCount = 1;
+  size_t ArrayStride = 0;
+  size_t NextRowOffset = llvm::alignTo(EndOffset, 16U);
+
+  if (LayoutTy->isArrayTy()) {
+    llvm::Type *Ty = LayoutTy;
+    while (Ty->isArrayTy()) {
+      ArrayCount *= Ty->getArrayNumElements();
+      Ty = Ty->getArrayElementType();
+    }
+    ElemSize =
+        Ty->isStructTy()
+            ? getOrCalculateStructSizeForBuffer(cast<llvm::StructType>(Ty))
+            : getScalarOrVectorSize(Ty);
+    ArrayStride = llvm::alignTo(ElemSize, 16U);
+    ElemOffset =
+        PackoffsetAttr ? PackoffsetAttr->getOffsetInBytes() : NextRowOffset;
+
+  } else if (LayoutTy->isStructTy()) {
+    ElemOffset =
+        PackoffsetAttr ? PackoffsetAttr->getOffsetInBytes() : NextRowOffset;
+    ElemSize =
+        getOrCalculateStructSizeForBuffer(cast<llvm::StructType>(LayoutTy));
+
+  } else {
+    size_t Align = 0;
+    if (LayoutTy->isVectorTy()) {
+      llvm::FixedVectorType *FVT = cast<llvm::FixedVectorType>(LayoutTy);
+      size_t SubElemSize = FVT->getElementType()->getScalarSizeInBits() / 8;
+      ElemSize = FVT->getNumElements() * SubElemSize;
+      Align = SubElemSize;
+    } else {
+      assert(LayoutTy->isIntegerTy() || LayoutTy->isFloatingPointTy());
+      ElemSize = LayoutTy->getScalarSizeInBits() / 8;
+      Align = ElemSize;
+    }
+    if (PackoffsetAttr) {
+      ElemOffset = PackoffsetAttr->getOffsetInBytes();
+    } else {
+      ElemOffset = llvm::alignTo(EndOffset, Align);
+      if (ElemOffset + ElemSize > NextRowOffset)
+        ElemOffset = NextRowOffset;
+    }
   }
 
-  auto *GV = cast<GlobalVariable>(CGM.GetAddrOfGlobalVar(D));
-  GV->setExternallyInitialized(true);
-  // Add debug info for constVal.
-  if (CGDebugInfo *DI = CGM.getModuleDebugInfo())
-    if (CGM.getCodeGenOpts().getDebugInfo() >=
-        codegenoptions::DebugInfoKind::LimitedDebugInfo)
-      DI->EmitGlobalVariable(cast<GlobalVariable>(GV), D);
-
-  // FIXME: support packoffset.
-  // See https://github.com/llvm/llvm-project/issues/57914.
-  uint32_t Offset = 0;
-  bool HasUserOffset = false;
-
-  unsigned LowerBound = HasUserOffset ? Offset : UINT_MAX;
-  CB.Constants.emplace_back(std::make_pair(GV, LowerBound));
+  // Update end offset of the buffer/struct layout; do not update it if
+  // the provided EndOffset is already bigger than the new one (which may happen
+  // with packoffset annotations)
+  unsigned NewEndOffset =
+      ElemOffset + (ArrayCount - 1) * ArrayStride + ElemSize;
+  EndOffset = std::max<size_t>(EndOffset, NewEndOffset);
+
+  // create metadata constan with the offset and stride and add to list
+  LayoutItems.push_back(getConstIntMetadata(CGM.getLLVMContext(), ElemOffset));
+  if (ArrayStride)
+    LayoutItems.push_back(
+        getConstIntMetadata(CGM.getLLVMContext(), ArrayStride));
 }
 
-void CGHLSLRuntime::addBufferDecls(const DeclContext *DC, Buffer &CB) {
-  for (Decl *it : DC->decls()) {
-    if (auto *ConstDecl = dyn_cast<VarDecl>(it)) {
-      addConstant(ConstDecl, CB);
-    } else if (isa<CXXRecordDecl, EmptyDecl>(it)) {
+void CGHLSLRuntime::emitBufferGlobalsAndMetadata(const HLSLBufferDecl *BufDecl,
+                                                 llvm::GlobalVariable *BufGV) {
+  llvm::StructType *LayoutStruct = cast<llvm::StructType>(
+      cast<llvm::TargetExtType>(BufGV->getValueType())->getTypeParameter(0));
+
+  LLVMContext &Ctx = CGM.getLLVMContext();
+
+  SmallVector<llvm::Metadata *> BufGlobals;
+  BufGlobals.push_back(ValueAsMetadata::get(BufGV));
+
+  SmallVector<llvm::Metadata *> LayoutItems;
+  LayoutItems.push_back(MDString::get(Ctx, LayoutStruct->getName()));
+
+  size_t BufferSize = 0;
+  size_t BufferSizeIndex = LayoutItems.size();
+  LayoutItems.push_back(nullptr); // reserve one slot for the buffer size
+
+  bool UsePackoffset = BufDecl->hasPackoffset();
+
+  const auto *ElemIt = LayoutStruct->element_begin();
+  for (Decl *D : BufDecl->decls()) {
+    if (isa<CXXRecordDecl, EmptyDecl>(D))
       // Nothing to do for this declaration.
-    } else if (isa<FunctionDecl>(it)) {
+      continue;
+    if (isa<FunctionDecl>(D)) {
       // A function within an cbuffer is effectively a top-level function,
       // as it only refers to globally scoped declarations.
-      CGM.EmitTopLevelDecl(it);
+      CGM.EmitTopLevelDecl(D);
+      continue;
+    }
+    if (VarDecl *VD = dyn_cast<VarDecl>(D)) {
+      QualType VDTy = VD->getType();
+      if (VDTy.getAddressSpace() != LangAS::hlsl_constant) {
+        if (VD->getStorageClass() == SC_Static ||
+            isResourceRecordTypeOrArrayOf(VDTy.getTypePtr())) {
+          // Emit static variables and resource classes inside cbuffer as
+          // regular globals
+          CGM.EmitGlobal(VD);
+        }
+        // Anything else that is not in the hlsl_constant address space must be
+        // an empty struct or a zero-sized array and can be ignored
+        continue;
+      }
+
+      assert(ElemIt != LayoutStruct->element_end() &&
+             "number of elements in layout struct does not match");
+      llvm::Type *LayoutType = *ElemIt++;
+
+      assert((CGM.getTypes().ConvertTypeForMem(VDTy) == LayoutType ||
+              (LayoutType->isStructTy() &&
+               cast<llvm::StructType>(LayoutType)
+                   ->getName()
+                   .starts_with(("struct.__cblayout_" +
+                                 VDTy->getAsCXXRecordDecl()->getName())
+                                    .str()))) &&
+             "layout type does not match the converted element type");
+
+      // handle any resources declarations inside the struct
+      if (VDTy->isStructureType() && VDTy->isHLSLIntangibleType())
+        // FIXME: handle resources in cbuffer structs
+        llvm_unreachable("resources in cbuffer are not supported yet");
+
+      GlobalVariable *ElemGV =
+          cast<GlobalVariable>(CGM.GetAddrOfGlobalVar(VD, LayoutType));
+      BufGlobals.push_back(ValueAsMetadata::get(ElemGV));
+
+      assert(((UsePackoffset && VD->hasAttr<HLSLPackOffsetAttr>()) ||
+              !UsePackoffset) &&
+             "expected packoffset attribute on every declaration");
+
+      addLayoutInfoForBufferElement(
+          BufferSize, LayoutItems, LayoutType,
+          UsePackoffset ? VD->getAttr<HLSLPackOffsetAttr>() : nullptr);
     }
   }
+  assert(ElemIt == LayoutStruct->element_end() &&
+         "number of elements in layout struct does not match");
+
+  // add buffer global and a list of its constants to metadata
+  MDNode *BufMDNode = MDNode::get(CGM.getLLVMContext(), BufGlobals);
+  CGM.getModule().getOrInsertNamedMetadata("hlsl.cbs")->addOperand(BufMDNode);
+
+  // set the size of the buffer
+  LayoutItems[BufferSizeIndex] = getConstIntMetadata(Ctx, BufferSize);
+
+  // add buffer layout to metadata
+  MDNode *LayoutMDNode = MDNode::get(CGM.getLLVMContext(), LayoutItems);
+  CGM.getModule()
+      .getOrInsertNamedMetadata("hlsl.cblayouts")
+      ->addOperand(LayoutMDNode);
 }
 
-void CGHLSLRuntime::addBuffer(const HLSLBufferDecl *D) {
-  Buffers.emplace_back(Buffer(D));
-  addBufferDecls(D, Buffers.back());
+// Creates resource handle type for the HLSL buffer
+static const clang::HLSLAttributedResourceType *
+createBufferHandleType(const HLSLBufferDecl *BufDecl) {
+  ASTContext &AST = BufDecl->getASTContext();
+  QualType QT = AST.getHLSLAttributedResourceType(
+      AST.HLSLResourceTy,
+      QualType(BufDecl->getLayoutStruct()->getTypeForDecl(), 0),
+      HLSLAttributedResourceType::Attributes(ResourceClass::CBuffer));
+  return cast<HLSLAttributedResourceType>(QT.getTypePtr());
+}
+
+// Creates temporary global variables for all declarations within the constant
+// buffer context, creates a global variable for the constant buffer and adds
+// it to the module.
+// All uses of the temporary constant globals will be replaced with buffer
+// access intrinsic resource.getpointer in CGHLSLRuntime::finishCodeGen.
+// Later on in DXILResourceAccess pass these will be transtaled
+// to dx.op.cbufferLoadLegacy instructions.
+void CGHLSLRuntime::addBuffer(const HLSLBufferDecl *BufDecl) {
+
+  assert(BufDecl->isCBuffer() && "tbuffer codegen is not supported yet");
+
+  // Create resource handle type for the buffer
+  const clang::HLSLAttributedResourceType *ResHandleTy =
+      createBufferHandleType(BufDecl);
+
+  // ignore empty constant buffer
+  if (ResHandleTy->getContainedType()->getAsCXXRecordDecl()->isEmpty())
+    return;
+
+  // Create global variable for the buffer
+  llvm::Module &M = CGM.getModule();
+  llvm::TargetExtType *TargetTy =
+      cast<llvm::TargetExtType>(convertHLSLSpecificType(ResHandleTy));
+  llvm::GlobalVariable *BufGV =
+      new GlobalVariable(TargetTy, /*isConstant*/ true,
+                         GlobalValue::LinkageTypes::ExternalLinkage, nullptr,
+                         llvm::formatv("{0}{1}", BufDecl->getName(),
+                                       BufDecl->isCBuffer() ? ".cb" : ".tb"),
+                         GlobalValue::NotThreadLocal);
+  M.insertGlobalVariable(BufGV);
+
+  // Add globals for buffer elements and create metadata node for the buffer
+  emitBufferGlobalsAndMetadata(BufDecl, BufGV);
+
+  // Add cbuffer resource initialization
+  const HLSLResourceBindingAttr *RBA =
+      BufDecl->getAttr<HLSLResourceBindingAttr>();
+  // FIXME: handle implicit binding if no binding attribute is found
+  if (RBA)
+    createResourceInitFn(CGM, BufGV, RBA->getSlotNumber(),
+                         RBA->getSpaceNumber());
 }
 
 void CGHLSLRuntime::finishCodeGen() {
@@ -173,28 +370,8 @@ void CGHLSLRuntime::finishCodeGen() {
   generateGlobalCtorDtorCalls();
   if (CGM.getCodeGenOpts().OptimizationLevel == 0)
     addDisableOptimizations(M);
-
-  const DataLayout &DL = M.getDataLayout();
-
-  for (auto &Buf : Buffers) {
-    layoutBuffer(Buf, DL);
-    GlobalVariable *GV = replaceBuffer(Buf);
-    M.insertGlobalVariable(GV);
-    llvm::hlsl::ResourceClass RC = Buf.IsCBuffer
-                                       ? llvm::hlsl::ResourceClass::CBuffer
-                                       : llvm::hlsl::ResourceClass::SRV;
-    llvm::hlsl::ResourceKind RK = Buf.IsCBuffer
-                                      ? llvm::hlsl::ResourceKind::CBuffer
-                                      : llvm::hlsl::ResourceKind::TBuffer;
-    addBufferResourceAnnotation(GV, RC, RK, /*IsROV=*/false,
-                                llvm::hlsl::ElementType::Invalid, Buf.Binding);
-  }
 }
 
-CGHLSLRuntime::Buffer::Buffer(const HLSLBufferDecl *D)
-    : Name(D->getName()), IsCBuffer(D->isCBuffer()),
-      Binding(D->getAttr<HLSLResourceBindingAttr>()) {}
-
 void CGHLSLRuntime::addBufferResourceAnnotation(llvm::GlobalVariable *GV,
                                                 llvm::hlsl::ResourceClass RC,
                                                 llvm::hlsl::ResourceKind RK,
@@ -521,21 +698,15 @@ void CGHLSLRuntime::generateGlobalCtorDtorCalls() {
   }
 }
 
-// Returns true if the type is an HLSL resource class
-static bool isResourceRecordType(const clang::Type *Ty) {
-  return HLSLAttributedResourceType::findHandleTypeOnResource(Ty) != nullptr;
-}
-
-static void createResourceInitFn(CodeGenModule &CGM, const VarDecl *VD,
-                                 llvm::GlobalVariable *GV, unsigned Slot,
-                                 unsigned Space) {
+static void createResourceInitFn(CodeGenModule &CGM, llvm::GlobalVariable *GV,
+                                 unsigned Slot, unsigned Space) {
   LLVMContext &Ctx = CGM.getLLVMContext();
   llvm::Type *Int1Ty = llvm::Type::getInt1Ty(Ctx);
 
   llvm::Function *InitResFunc = llvm::Function::Create(
       llvm::FunctionType::get(CGM.VoidTy, false),
       llvm::GlobalValue::InternalLinkage,
-      ("_init_resource_" + VD->getName()).str(), CGM.getModule());
+      ("_init_resource_" + GV->getName()).str(), CGM.getModule());
   InitResFunc->addFnAttr(llvm::Attribute::AlwaysInline);
 
   llvm::BasicBlock *EntryBB =
@@ -544,20 +715,15 @@ static void createResourceInitFn(CodeGenModule &CGM, const VarDecl *VD,
   const DataLayout &DL = CGM.getModule().getDataLayout();
   Builder.SetInsertPoint(EntryBB);
 
-  const HLSLAttributedResourceType *AttrResType =
-      HLSLAttributedResourceType::findHandleTypeOnResource(
-          VD->getType().getTypePtr());
-
-  // FIXME: Only simple declarations of resources are supported for now.
-  // Arrays of resources or resources in user defined classes are
-  // not implemented yet.
-  assert(AttrResType != nullptr &&
-         "Resource class must have a handle of HLSLAttributedResourceType");
-
-  llvm::Type *TargetTy =
-      CGM.getTargetCodeGenInfo().getHLSLType(CGM, AttrResType);
-  assert(TargetTy != nullptr &&
-         "Failed to convert resource handle to target type");
+  // Make sure the global variable is resource handle (cbuffer) or
+  // resource class (=class where the first element is a resource handle).
+  llvm::Type *HandleTy = GV->getValueType();
+  assert((HandleTy->isTargetExtTy() ||
+          (HandleTy->isStructTy() &&
+           HandleTy->getStructElementType(0)->isTargetExtTy())) &&
+         "unexpected type of the global");
+  if (!HandleTy->isTargetExtTy())
+    HandleTy = HandleTy->getStructElementType(0);
 
   llvm::Value *Args[] = {
       llvm::ConstantInt::get(CGM.IntTy, Space), /* reg_space */
@@ -569,9 +735,9 @@ static void createResourceInitFn(CodeGenModule &CGM, const VarDecl *VD,
       llvm::ConstantInt::get(Int1Ty, false) /* non-uniform */
   };
   llvm::Value *CreateHandle = Builder.CreateIntrinsic(
-      /*ReturnType=*/TargetTy,
+      /*ReturnType=*/HandleTy,
       CGM.getHLSLRuntime().getCreateHandleFromBindingIntrinsic(), Args, nullptr,
-      Twine(VD->getName()).concat("_h"));
+      Twine(GV->getName()).concat("_h"));
 
   llvm::Value *HandleRef = Builder.CreateStructGEP(GV->getValueType(), GV, 0);
   Builder.CreateAlignedStore(CreateHandle, HandleRef,
@@ -598,8 +764,7 @@ void CGHLSLRuntime::handleGlobalVarDefinition(const VarDecl *VD,
     // not implemented yet.
     return;
 
-  createResourceInitFn(CGM, VD, GV, RBA->getSlotNumber(),
-                       RBA->getSpaceNumber());
+  createResourceInitFn(CGM, GV, RBA->getSlotNumber(), RBA->getSpaceNumber());
 }
 
 llvm::Instruction *CGHLSLRuntime::getConvergenceToken(BasicBlock &BB) {
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.h b/clang/lib/CodeGen/CGHLSLRuntime.h
index 032b2dee82f211..a6e3c78f522851 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.h
+++ b/clang/lib/CodeGen/CGHLSLRuntime.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_CLANG_LIB_CODEGEN_CGHLSLRUNTIME_H
 #define LLVM_CLANG_LIB_CODEGEN_CGHLSLRUNTIME_H
 
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/IntrinsicsDirectX.h"
@@ -46,25 +47,31 @@
     }                                                                          \
   }
 
+using ResourceClass = llvm::dxil::ResourceClass;
+
 namespace llvm {
 class GlobalVariable;
 class Function;
 class StructType;
+class Metadata;
 } // namespace llvm
 
 namespace clang {
+class NamedDecl;
 class VarDecl;
 class ParmVarDecl;
 class HLSLBufferDecl;
 class HLSLResourceBindingAttr;
 class Type;
 class DeclContext;
+class HLSLPackOffsetAttr;
 
 class FunctionDecl;
 
 namespace CodeGen {
 
 class CodeGenModule;
+class CGBuilderTy;
 
 class CGHLSLRuntime {
 public:
@@ -124,16 +131,6 @@ class CGHLSLRuntime {
     unsigned Space;
     BufferResBinding(HLSLResourceBindingAttr *Attr);
   };
-  struct Buffer {
-    Buffer(const HLSLBufferDecl *D);
-    llvm::StringRef Name;
-    // IsCBuffer - Whether the buffer is a cbuffer (and not a tbuffer).
-    bool IsCBuffer;
-    BufferResBinding Binding;
-    // Global variable and offset for each constant.
-    std::vector<std::pair<llvm::GlobalVariable *, unsigned>> Constants;
-    llvm::StructType *LayoutStruct = nullptr;
-  };
 
 protected:
   CodeGenModule &CGM;
@@ -167,10 +164,18 @@ class CGHLSLRuntime {
                                    llvm::hlsl::ResourceKind RK, bool IsROV,
                                    llvm::hlsl::ElementType ET,
                                    BufferResBinding &Binding);
-  void addConstant(VarDecl *D, Buffer &CB);
-  void addBufferDecls(const DeclContext *DC, Buffer &CB);
+  void emitBufferGlobalsAndMetadata(const HLSLBufferDecl *BufDecl,
+                                    llvm::GlobalVariable *BufGV);
+  void addLayoutInfoForBufferElement(
+      size_t &EndOffset, SmallVector<llvm::Metadata *> &LayoutItems,
+      llvm::Type *LayoutTy, HLSLPackOffsetAttr *PackoffsetAttr = nullptr);
+
+  size_t getOrCalculateStructSizeForBuffer(llvm::StructType *StructTy);
+
   llvm::Triple::ArchType getArch();
-  llvm::SmallVector<Buffer> Buffers;
+
+  // sizes of structs that in constant buffer layout
+  llvm::DenseMap<llvm::StructType *, size_t> StructSizesForBuffer;
 };
 
 } // namespace CodeGen
diff --git a/clang/lib/CodeGen/Targets/DirectX.cpp b/clang/lib/CodeGen/Targets/DirectX.cpp
index 7935f7ae370047..33bddc56d83f24 100644
--- a/clang/lib/CodeGen/Targets/DirectX.cpp
+++ b/clang/lib/CodeGen/Targets/DirectX.cpp
@@ -44,6 +44,7 @@ llvm::Type *DirectXTargetCodeGenInfo::getHLSLType(CodeGenModule &CGM,
       return nullptr;
 
     // convert element type
+    // llvm::Type *ElemType = CGM.getTypes().ConvertTypeForMem(ContainedTy);
     llvm::Type *ElemType = CGM.getTypes().ConvertType(ContainedTy);
 
     llvm::StringRef TypeName =
@@ -56,9 +57,13 @@ llvm::Type *DirectXTargetCodeGenInfo::getHLSLType(CodeGenModule &CGM,
 
     return llvm::TargetExtType::get(Ctx, TypeName, {ElemType}, Ints);
   }
-  case llvm::dxil::ResourceClass::CBuffer:
-    llvm_unreachable("dx.CBuffer handles are not implemented yet");
-    break;
+  case llvm::dxil::ResourceClass::CBuffer: {
+    QualType StructTy = ResType->getContainedType();
+    if (StructTy.isNull())
+      return nullptr;
+    llvm::Type *Ty = CGM.getTypes().ConvertType(StructTy);
+    return llvm::TargetExtType::get(Ctx, "dx.CBuffer", {Ty});
+  }
   case llvm::dxil::ResourceClass::Sampler:
     llvm_unreachable("dx.Sampler handles are not implemented yet");
     break;
diff --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp
index b71dd2b273a1c6..2807cc773320b2 100644
--- a/clang/lib/Sema/SemaHLSL.cpp
+++ b/clang/lib/Sema/SemaHLSL.cpp
@@ -239,6 +239,7 @@ static void validatePackoffset(Sema &S, HLSLBufferDecl *BufDecl) {
 
   // Make sure there is no overlap in packoffset - sort PackOffsetVec by offset
   // and compare adjacent values.
+  bool IsValid = true;
   ASTContext &Context = S.getASTContext();
   std::sort(PackOffsetVec.begin(), PackOffsetVec.end(),
             [](const std::pair<VarDecl *, HLSLPackOffsetAttr *> &LHS,
@@ -257,8 +258,10 @@ static void validatePackoffset(Sema &S, HLSLBufferDecl *BufDecl) {
       VarDecl *NextVar = PackOffsetVec[i + 1].first;
       S.Diag(NextVar->getLocation(), diag::err_hlsl_packoffset_overlap)
           << NextVar << Var;
+      IsValid = false;
     }
   }
+  BufDecl->setHasPackoffset(IsValid);
 }
 
 // Returns true if the array has a zero size = if any of the dimensions is 0
diff --git a/clang/test/CodeGenHLSL/cbuf.hlsl b/clang/test/CodeGenHLSL/cbuf.hlsl
deleted file mode 100644
index 825e7b8161a601..00000000000000
--- a/clang/test/CodeGenHLSL/cbuf.hlsl
+++ /dev/null
@@ -1,33 +0,0 @@
-// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.3-library %s \
-// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
-
-// RUN: %clang_cc1 -finclude-default-header -triple spirv-pc-vulkan-library %s \
-// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
-
-// CHECK: @a = external addrspace(2) externally_initialized global float, align 4
-// CHECK: @b = external addrspace(2) externally_initialized global double, align 8
-// CHECK: @c = external addrspace(2) externally_initialized global float, align 4
-// CHECK: @d = external addrspace(2) externally_initialized global double, align 8
-
-// CHECK: @[[CB:.+]] = external constant { float, double }
-cbuffer A : register(b0, space2) {
-  float a;
-  double b;
-}
-
-// CHECK: @[[TB:.+]] = external constant { float, double }
-tbuffer A : register(t2, space1) {
-  float c;
-  double d;
-}
-
-float foo() {
-// CHECK: load float, ptr addrspace(2) @a, align 4
-// CHECK: load double, ptr addrspace(2) @b, align 8
-// CHECK: load float, ptr addrspace(2) @c, align 4
-// CHECK: load double, ptr addrspace(2) @d, align 8
-  return a + b + c*d;
-}
-
-// CHECK: !hlsl.cbufs = !{![[CBMD:[0-9]+]]}
-// CHECK: ![[CBMD]] = !{ptr @[[CB]], i32 13, i32 0, i1 false, i32 0, i32 2}
diff --git a/clang/test/CodeGenHLSL/cbuf_in_namespace.hlsl b/clang/test/CodeGenHLSL/cbuf_in_namespace.hlsl
deleted file mode 100644
index 13c401d4283313..00000000000000
--- a/clang/test/CodeGenHLSL/cbuf_in_namespace.hlsl
+++ /dev/null
@@ -1,29 +0,0 @@
-// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.3-library %s \
-// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
-
-// RUN: %clang_cc1 -finclude-default-header -triple spirv-pc-vulkan-library %s \
-// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
-
-// Make sure cbuffer inside namespace works.
-
-// CHECK: @_ZN2n02n11aE = external addrspace(2) externally_initialized global float, align 4
-// CHECK: @_ZN2n01bE = external addrspace(2) externally_initialized global float, align 4
-
-// CHECK: @[[CB:.+]] = external constant { float }
-// CHECK: @[[TB:.+]] = external constant { float }
-namespace n0 {
-namespace n1 {
-  cbuffer A {
-    float a;
-  }
-}
-  tbuffer B {
-    float b;
-  }
-}
-
-float foo() {
-// CHECK: load float, ptr addrspace(2) @_ZN2n02n11aE, align 4
-// CHECK: load float, ptr addrspace(2) @_ZN2n01bE, align 4
-  return n0::n1::a + n0::b;
-}
diff --git a/clang/test/CodeGenHLSL/cbuffer.hlsl b/clang/test/CodeGenHLSL/cbuffer.hlsl
new file mode 100644
index 00000000000000..99f16ea62cdcbc
--- /dev/null
+++ b/clang/test/CodeGenHLSL/cbuffer.hlsl
@@ -0,0 +1,200 @@
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.3-compute \
+// RUN:   -fnative-half-type -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s
+
+// CHECK: %struct.__cblayout_CBScalars = type <{ float, double, half, i64, i32, i16, i32, i64 }>
+// CHECK: %struct.__cblayout_CBVectors = type <{ <3 x float>, <3 x double>, <2 x half>, <3 x i64>, <4 x i32>, <3 x i16>, <3 x i64> }>
+// CHECK: %struct.__cblayout_CBArrays = type <{ [3 x float], [2 x <3 x double>], [2 x [2 x half]], [3 x i64], [2 x [3 x [4 x <4 x i32>]]], [1 x i16], [2 x i64], [4 x i32] }>
+// CHECK: %struct.__cblayout_CBStructs = type { %struct.A, %struct.B, %struct.C, [5 x %struct.A], %struct.__cblayout_D, half, %struct.B, <3 x i16> }
+// CHECK: %struct.A = type { <2 x float> }
+// CHECK: %struct.C = type { i32, %struct.A }
+// CHECK: %struct.__cblayout_D = type { [2 x [3 x %struct.B]] }
+// CHECK: %struct.B = type { %struct.A, <3 x i16> }
+
+cbuffer CBScalars : register(b1, space5) {
+  float a1;
+  double a2;
+  float16_t a3;
+  uint64_t a4;
+  int a5;
+  uint16_t a6;
+  bool a7;
+  int64_t a8;
+}
+
+// CHECK: @CBScalars.cb = external constant target("dx.CBuffer", %struct.__cblayout_CBScalars)
+// CHECK: @a1 = external addrspace(2) global float, align 4
+// CHECK: @a2 = external addrspace(2) global double, align 8
+// CHECK: @a3 = external addrspace(2) global half, align 2
+// CHECK: @a4 = external addrspace(2) global i64, align 8
+// CHECK: @a5 = external addrspace(2) global i32, align 4
+// CHECK: @a6 = external addrspace(2) global i16, align 2
+// CHECK: @a7 = external addrspace(2) global i32, align 4
+// CHECK: @a8 = external addrspace(2) global i64, align 8
+
+cbuffer CBVectors {
+  float3 b1;
+  double3 b2;
+  float16_t2 b3;
+  uint64_t3 b4;
+  int4 b5;
+  uint16_t3 b6;
+  int64_t3 b7;
+  // FIXME: add s bool vectors after llvm-project/llvm#91639 is added
+}
+
+// CHECK: @CBVectors.cb = external constant target("dx.CBuffer", %struct.__cblayout_CBVectors)
+// CHECK: @b1 = external addrspace(2) global <3 x float>, align 16
+// CHECK: @b2 = external addrspace(2) global <3 x double>, align 32
+// CHECK: @b3 = external addrspace(2) global <2 x half>, align 4
+// CHECK: @b4 = external addrspace(2) global <3 x i64>, align 32
+// CHECK: @b5 = external addrspace(2) global <4 x i32>, align 16
+// CHECK: @b6 = external addrspace(2) global <3 x i16>, align 8
+// CHECK: @b7 = external addrspace(2) global <3 x i64>, align 32
+
+cbuffer CBArrays : register(b2) {
+  float c1[3];
+  double3 c2[2];
+  float16_t c3[2][2];
+  uint64_t c4[3];
+  int4 c5[2][3][4];
+  uint16_t c6[1];
+  int64_t c7[2];
+  bool c8[4];
+}
+
+// CHECK: @CBArrays.cb = external constant target("dx.CBuffer", %struct.__cblayout_CBArrays)
+// CHECK: @c1 = external addrspace(2) global [3 x float], align 4
+// CHECK: @c2 = external addrspace(2) global [2 x <3 x double>], align 32
+// CHECK: @c3 = external addrspace(2) global [2 x [2 x half]], align 2
+// CHECK: @c4 = external addrspace(2) global [3 x i64], align 8
+// CHECK: @c5 = external addrspace(2) global [2 x [3 x [4 x <4 x i32>]]], align 16
+// CHECK: @c6 = external addrspace(2) global [1 x i16], align 2
+// CHECK: @c7 = external addrspace(2) global [2 x i64], align 8
+// CHECK: @c8 = external addrspace(2) global [4 x i32], align 4
+
+struct Empty {};
+
+struct A {
+  float2 f1;
+};
+
+struct B : A {
+  uint16_t3 f2;
+};
+
+struct C {
+  int i;
+  A f3;
+};
+
+struct D {
+  B array_of_B[2][3];
+  Empty es;
+};
+
+// CHECK: @CBStructs.cb = external constant target("dx.CBuffer", %struct.__cblayout_CBStructs)
+// CHECK: @a = external addrspace(2) global %struct.A, align 8
+// CHECK: @b = external addrspace(2) global %struct.B, align 8
+// CHECK: @c = external addrspace(2) global %struct.C, align 8
+// CHECK: @array_of_A = external addrspace(2) global [5 x %struct.A], align 8
+// CHECK: @d = external addrspace(2) global %struct.__cblayout_D, align 8
+// CHECK: @e = external addrspace(2) global half, align 2
+
+cbuffer CBStructs {
+  A a;
+  B b;
+  C c;
+  A array_of_A[5];
+  D d;
+  half e;
+  B f;
+  uint16_t3 g;
+};
+
+struct Test {
+    float a, b;
+};
+
+// CHECK: @CBMix.cb = external constant target("dx.CBuffer", %struct.__cblayout_CBMix)
+// CHECK: @test = external addrspace(2) global [2 x %struct.Test], align 4
+// CHECK: @f1 = external addrspace(2) global float, align 4
+// CHECK: @f2 = external addrspace(2) global [3 x [2 x <2 x float>]], align 8
+// CHECK: @f3 = external addrspace(2) global float, align 4
+// CHECK: @s = external addrspace(2) global %struct.anon, align 4
+// CHECK: @dd = external addrspace(2) global double, align 8
+// CHECK: @f4 = external addrspace(2) global float, align 4
+// CHECK: @dv = external addrspace(2) global <1 x double>, align 8
+// CHECK: @uv = external addrspace(2) global i16, align 2
+
+cbuffer CBMix {
+    Test test[2];
+    float f1;
+    float2 f2[3][2];
+    float f3;
+    struct { float c; } s;
+    double dd;
+    float f4;
+    vector<double,1> dv;
+    uint16_t uv;
+};  
+
+// CHECK: efine internal void @_init_resource_CBScalars.cb()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %[[HANDLE1:.*]] = call target("dx.CBuffer", %struct.__cblayout_CBScalars)
+// CHECK-SAME: @llvm.dx.resource.handlefrombinding.tdx.CBuffer_s_struct.__cblayout_CBScalarsst(i32 5, i32 1, i32 1, i32 0, i1 false)
+// CHECK-NEXT: store target("dx.CBuffer", %struct.__cblayout_CBScalars) %[[HANDLE1]], ptr @CBScalars.cb, align 4
+
+// CHECK: define internal void @_init_resource_CBArrays.cb()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %[[HANDLE2:.*]] = call target("dx.CBuffer", %struct.__cblayout_CBArrays)
+// CHECK-SAME: @llvm.dx.resource.handlefrombinding.tdx.CBuffer_s_struct.__cblayout_CBArraysst(i32 0, i32 2, i32 1, i32 0, i1 false)
+// CHECK-NEXT: store target("dx.CBuffer", %struct.__cblayout_CBArrays) %[[HANDLE2]], ptr @CBArrays.cb, align 4
+
+RWBuffer<float> Buf;
+
+[numthreads(4,1,1)]
+void main() {
+  //Buf[0] = a1 + b1.z + c1[2] + a.f1.y;
+  Buf[0] = a.f1.y;
+}
+
+// CHECK: define internal void @_GLOBAL__sub_I_cbuffer.hlsl()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: call void @_init_resource_CBScalars.cb()
+// CHECK-NEXT: call void @_init_resource_CBArrays.cb()
+
+// CHECK: !hlsl.cbs = !{![[CBSCALARS:[0-9]+]], ![[CBVECTORS:[0-9]+]], ![[CBARRAYS:[0-9]+]], ![[CBSTRUCTS:[0-9]+]], ![[CBMIX:[0-9]+]]}
+// CHECK: !hlsl.cblayouts = !{![[CBSCALARS_LAYOUT:[0-9]+]], ![[CBVECTORS_LAYOUT:[0-9]+]], ![[CBARRAYS_LAYOUT:[0-9]+]], ![[A_LAYOUT:[0-9]+]],
+// CHECK-SAME: ![[B_LAYOUT:[0-9]+]], ![[C_LAYOUT:[0-9]+]], ![[D_LAYOUT:[0-9]+]], ![[CBSTRUCTS_LAYOUT:[0-9]+]], ![[TEST_LAYOUT:[0-9]+]],
+// CHECK-SAME: ![[ANON_LAYOUT:[0-9]+]], ![[CBMIX_LAYOUT:[0-9]+]]}
+
+// CHECK: ![[CBSCALARS]] = !{ptr @CBScalars.cb, ptr addrspace(2) @a1, ptr addrspace(2) @a2, ptr addrspace(2) @a3, ptr addrspace(2) @a4,
+// CHECK-SAME: ptr addrspace(2) @a5, ptr addrspace(2) @a6, ptr addrspace(2) @a7, ptr addrspace(2) @a8}
+
+// CHECK: ![[CBVECTORS]] = !{ptr @CBVectors.cb, ptr addrspace(2) @b1, ptr addrspace(2) @b2, ptr addrspace(2) @b3, ptr addrspace(2) @b4,
+// CHECK-SAME: ptr addrspace(2) @b5, ptr addrspace(2) @b6, ptr addrspace(2) @b7}
+
+// CHECK: ![[CBARRAYS]] = !{ptr @CBArrays.cb, ptr addrspace(2) @c1, ptr addrspace(2) @c2, ptr addrspace(2) @c3, ptr addrspace(2) @c4, 
+// CHECK-SAME: ptr addrspace(2) @c5, ptr addrspace(2) @c6, ptr addrspace(2) @c7, ptr addrspace(2) @c8}
+
+// CHECK: ![[CBSTRUCTS]] = !{ptr @CBStructs.cb, ptr addrspace(2) @a, ptr addrspace(2) @b, ptr addrspace(2) @c, ptr addrspace(2) @array_of_A, 
+// CHECK-SAME: ptr addrspace(2) @d, ptr addrspace(2) @e, ptr addrspace(2) @f, ptr addrspace(2) @g}
+
+// CHECK: ![[CBMIX]] = !{ptr @CBMix.cb, ptr addrspace(2) @test, ptr addrspace(2) @f1, ptr addrspace(2) @f2, ptr addrspace(2) @f3,
+// CHECK-SAME: ptr addrspace(2) @s, ptr addrspace(2) @dd, ptr addrspace(2) @f4, ptr addrspace(2) @dv, ptr addrspace(2) @uv}
+
+// CHECK: ![[CBSCALARS_LAYOUT]] = !{!"struct.__cblayout_CBScalars", i32 56, i32 0, i32 8, i32 16, i32 24, i32 32, i32 36, i32 40, i32 48}
+// CHECK: ![[CBVECTORS_LAYOUT]] = !{!"struct.__cblayout_CBVectors", i32 136, i32 0, i32 16, i32 40, i32 48, i32 80, i32 96, i32 112}
+                                  
+// CHECK: ![[CBARRAYS_LAYOUT]] = !{!"struct.__cblayout_CBArrays", i32 708, i32 0, i32 16, i32 48, i32 32, i32 112, i32 16, i32 176, i32 16,
+// CHECK-SAME: i32 224, i32 16, i32 608, i32 16, i32 624, i32 16, i32 656, i32 16}
+
+// CHECK: ![[A_LAYOUT]] = !{!"struct.A", i32 8, i32 0}
+// CHECK: ![[B_LAYOUT]] = !{!"struct.B", i32 14, i32 0, i32 8}
+// CHECK: ![[C_LAYOUT]] = !{!"struct.C", i32 24, i32 0, i32 16}
+// CHECK: ![[D_LAYOUT]] = !{!"struct.__cblayout_D", i32 94, i32 0, i32 16}
+// CHECK: ![[CBSTRUCTS_LAYOUT]] = !{!"struct.__cblayout_CBStructs", i32 262, i32 0, i32 16, i32 32, i32 64, i32 16, i32 144, i32 238, i32 240, i32 256}
+
+// CHECK: ![[TEST_LAYOUT]] = !{!"struct.Test", i32 8, i32 0, i32 4}
+// CHECK: ![[ANON_LAYOUT]] = !{!"struct.anon", i32 4, i32 0}
+// CHECK: ![[CBMIX_LAYOUT]] = !{!"struct.__cblayout_CBMix", i32 162, i32 0, i32 16, i32 24, i32 32, i32 16, i32 120, i32 128, i32 136, i32 144, i32 152, i32 160}
diff --git a/clang/test/CodeGenHLSL/cbuffer_and_namespaces.hlsl b/clang/test/CodeGenHLSL/cbuffer_and_namespaces.hlsl
new file mode 100644
index 00000000000000..aa5659af414efa
--- /dev/null
+++ b/clang/test/CodeGenHLSL/cbuffer_and_namespaces.hlsl
@@ -0,0 +1,63 @@
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s \
+// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
+
+// Make sure cbuffer inside namespace works.
+
+// CHECK: %"struct.n0::n1::__cblayout_A" = type { float }
+// CHECK: %"struct.n0::__cblayout_B" = type { float }
+// CHECK: %"struct.n0::n2::__cblayout_C" = type { float, %"struct.n0::Foo" }
+// CHECK: %"struct.n0::Foo" = type { float }
+
+// CHECK: @A.cb = external constant target("dx.CBuffer", %"struct.n0::n1::__cblayout_A")
+// CHECK: @_ZN2n02n11aE = external addrspace(2) global float, align 4
+
+// CHECK: @B.cb = external constant target("dx.CBuffer", %"struct.n0::__cblayout_B")
+// CHECK: @_ZN2n01aE = external addrspace(2) global float, align 4
+
+// CHECK: @C.cb = external constant target("dx.CBuffer", %"struct.n0::n2::__cblayout_C")
+// CHECK: @_ZN2n02n21aE = external addrspace(2) global float, align 4
+// CHECK: @_ZN2n02n21bE = external addrspace(2) global %"struct.n0::Foo", align 4
+
+namespace n0 {
+  struct Foo {
+    float f;
+  };
+
+  namespace n1 {
+    cbuffer A {
+      float a;
+    }
+  }
+  cbuffer B {
+    float a;
+  }
+  namespace n2 {
+    cbuffer C {
+      float a;
+      Foo b;
+    }
+  }
+}
+
+float foo() {
+  // CHECK: load float, ptr addrspace(2) @_ZN2n02n11aE, align 4
+  // CHECK: load float, ptr addrspace(2) @_ZN2n01aE, align 4
+  // CHECK: load float, ptr addrspace(2) @_ZN2n02n21aE, align 4
+  return n0::n1::a + n0::a + n0::n2::a;
+}
+
+[numthreads(4,1,1)]
+void main() {}
+
+// CHECK: !hlsl.cbs = !{![[A:[0-9]+]], ![[B:[0-9]+]], ![[C:[0-9]+]]}
+// CHECK: !hlsl.cblayouts = !{![[A_LAYOUT:[0-9]+]], ![[B_LAYOUT:[0-9]+]], ![[FOO_LAYOUT:[0-9]+]], ![[C_LAYOUT:[0-9]+]]}
+
+// CHECK: [[A]] = !{ptr @A.cb, ptr addrspace(2) @_ZN2n02n11aE}
+// CHECK: [[B]] = !{ptr @B.cb, ptr addrspace(2) @_ZN2n01aE}
+// CHECK: [[C]] = !{ptr @C.cb, ptr addrspace(2) @_ZN2n02n21aE, ptr addrspace(2) @_ZN2n02n21bE}
+
+// CHECK: ![[A_LAYOUT]] = !{!"struct.n0::n1::__cblayout_A", i32 4, i32 0}
+// CHECK: ![[B_LAYOUT]] = !{!"struct.n0::__cblayout_B", i32 4, i32 0}
+// CHECK: ![[FOO_LAYOUT]] = !{!"struct.n0::Foo", i32 4, i32 0}
+// CHECK: ![[C_LAYOUT]] = !{!"struct.n0::n2::__cblayout_C", i32 20, i32 0, i32 16}
diff --git a/clang/test/CodeGenHLSL/cbuffer_with_packoffset.hlsl b/clang/test/CodeGenHLSL/cbuffer_with_packoffset.hlsl
new file mode 100644
index 00000000000000..f5b5cba6197b39
--- /dev/null
+++ b/clang/test/CodeGenHLSL/cbuffer_with_packoffset.hlsl
@@ -0,0 +1,40 @@
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-compute %s \
+// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
+
+// CHECK: %struct.__cblayout_CB = type <{ float, double, <2 x i32> }>
+
+// CHECK: @CB.cb = external constant target("dx.CBuffer", %struct.__cblayout_CB)
+// CHECK: @a = external addrspace(2) global float, align 4
+// CHECK: @b = external addrspace(2) global double, align 8
+// CHECK: @c = external addrspace(2) global <2 x i32>, align 8
+
+cbuffer CB : register(b1, space3) {
+  float a : packoffset(c1.x);
+  double b : packoffset(c10.z);
+  int2 c : packoffset(c5.z);
+}
+
+// CHECK: define internal void @_init_resource_CB.cb()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %CB.cb_h = call target("dx.CBuffer", %struct.__cblayout_CB) @llvm.dx.resource.handlefrombinding.tdx.CBuffer_s_struct.__cblayout_CBst(i32 3, i32 1, i32 1, i32 0, i1 false)
+
+float foo() {
+  // CHECK: load float, ptr addrspace(2) @a, align 4
+  // CHECK: load double, ptr addrspace(2) @b, align 8
+  return a + b;
+}
+// CHECK: define internal void @_GLOBAL__sub_I_cbuffer_with_packoffset.hlsl()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: call void @_init_resource_CB.cb()
+
+[numthreads(4,1,1)]
+void main() {
+  foo();
+}
+
+// CHECK: !hlsl.cbs = !{![[CB:[0-9]+]]}
+// CHECK: !hlsl.cblayouts = !{![[CB_LAYOUT:[0-9]+]]}
+
+// CHECK: ![[CB]] = !{ptr @CB.cb, ptr addrspace(2) @a, ptr addrspace(2) @b, ptr addrspace(2) @c}
+// CHECK: ![[CB_LAYOUT]] = !{!"struct.__cblayout_CB", i32 176, i32 16, i32 168, i32 88}
diff --git a/clang/test/CodeGenHLSL/cbuffer_with_static_global_and_function.hlsl b/clang/test/CodeGenHLSL/cbuffer_with_static_global_and_function.hlsl
new file mode 100644
index 00000000000000..8994640d5b3112
--- /dev/null
+++ b/clang/test/CodeGenHLSL/cbuffer_with_static_global_and_function.hlsl
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.3-library %s \
+// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
+
+// CHECK: %struct.__cblayout_A = type { float }
+
+// CHECK: @A.cb = external constant target("dx.CBuffer", %struct.__cblayout_A)
+// CHECK: @a = external addrspace(2) global float, align 4
+// CHECK-DAG: @_ZL1b = internal global float 3.000000e+00, align 4
+// CHECK-NOT: @B.cb
+
+cbuffer A {
+  float a;
+  static float b = 3;
+  float foo() { return a + b; }
+}
+
+cbuffer B {
+  // intentionally empty
+}
+
+// CHECK: define {{.*}} float @_Z3foov() #0 {
+// CHECK: load float, ptr addrspace(2) @a, align 4
+
+extern float bar() {
+  return foo();
+}
+
+// CHECK: !hlsl.cbs = !{![[CB:[0-9]+]]}
+// CHECK: !hlsl.cblayouts = !{![[CB_LAYOUT:[0-9]+]]}
+
+// CHECK: ![[CB]] = !{ptr @A.cb, ptr addrspace(2) @a}
+// CHECK: ![[CB_LAYOUT]] = !{!"struct.__cblayout_A", i32 4, i32 0}
diff --git a/clang/test/CodeGenHLSL/resource-bindings.hlsl b/clang/test/CodeGenHLSL/resource-bindings.hlsl
index bfa7896bd98114..57e8cc29572b1f 100644
--- a/clang/test/CodeGenHLSL/resource-bindings.hlsl
+++ b/clang/test/CodeGenHLSL/resource-bindings.hlsl
@@ -2,14 +2,17 @@
 
 // CHECK: define internal void @_init_resource_U0S0()
 // CHECK: %U0S0_h = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0) @llvm.dx.resource.handlefrombinding.tdx.TypedBuffer_v4f32_1_0_0t(i32 0, i32 0, i32 1, i32 0, i1 false)
+// CHECK: store target("dx.TypedBuffer", <4 x float>, 1, 0, 0) %U0S0_h, ptr @U0S0, align 4
 RWBuffer<float4> U0S0 : register(u0);
 
 // CHECK: define internal void @_init_resource_U5S3()
 // CHECK: %U5S3_h = call target("dx.TypedBuffer", float, 1, 0, 0) @llvm.dx.resource.handlefrombinding.tdx.TypedBuffer_f32_1_0_0t(i32 3, i32 5, i32 1, i32 0, i1 false)
+// CHECK: store target("dx.TypedBuffer", float, 1, 0, 0) %U5S3_h, ptr @U5S3, align 4
 RWBuffer<float> U5S3 : register(u5, space3);
 
 // CHECK: define internal void @_init_resource_T2S2()
 // CHECK: %T2S2_h = call target("dx.RawBuffer", i32, 0, 0) @llvm.dx.resource.handlefrombinding.tdx.RawBuffer_i32_0_0t(i32 2, i32 2, i32 1, i32 0, i1 false)
+// CHECK: store target("dx.RawBuffer", i32, 0, 0) %T2S2_h, ptr @T2S2, align 4
 StructuredBuffer<int> T2S2 : register(t2, space2);
 struct S {
   float4 f;
@@ -18,6 +21,7 @@ struct S {
 
 // CHECK: define internal void @_init_resource_T3S0()
 // CHECK: %T3S0_h = call target("dx.RawBuffer", %struct.S, 0, 0) @llvm.dx.resource.handlefrombinding.tdx.RawBuffer_s_struct.Ss_0_0t(i32 0, i32 3, i32 1, i32 0, i1 false)
+// CHECK: store target("dx.RawBuffer", %struct.S, 0, 0) %T3S0_h, ptr @T3S0, align 4
 StructuredBuffer<S> T3S0 : register(t3);
 
 // CHECK: define void @main()
diff --git a/clang/test/CodeGenHLSL/static_global_and_function_in_cb.hlsl b/clang/test/CodeGenHLSL/static_global_and_function_in_cb.hlsl
deleted file mode 100644
index 25f51cce2017d2..00000000000000
--- a/clang/test/CodeGenHLSL/static_global_and_function_in_cb.hlsl
+++ /dev/null
@@ -1,22 +0,0 @@
-// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.3-library %s \
-// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
-
-// RUN: %clang_cc1 -finclude-default-header -triple spirv-pc-vulkan-library %s \
-// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s
-
-cbuffer A {
-  // CHECK: @a = external addrspace(2) externally_initialized global float, align 4
-  float a;
-  // CHECK: @_ZL1b = internal global float 3.000000e+00, align 4
-  static float b = 3;
-  float foo() { return a + b; }
-}
-// CHECK: @[[CB:.+]] = external constant { float }
-
-// CHECK:define {{.*}} float @_Z3foov()
-// CHECK:load float, ptr addrspace(2) @a, align 4
-// CHECK:load float, ptr @_ZL1b, align 4
-
-float bar() {
-  return foo();
-}

>From 56beb45a133be18b7e6649cc0a4af852bbed3db7 Mon Sep 17 00:00:00 2001
From: Helena Kotas <hekotas at microsoft.com>
Date: Tue, 28 Jan 2025 16:06:03 -0800
Subject: [PATCH 2/4] remove stride

---
 clang/lib/CodeGen/CGHLSLRuntime.cpp | 32 +++++++++++++++--------------
 clang/lib/CodeGen/CGHLSLRuntime.h   |  7 ++++---
 clang/test/CodeGenHLSL/cbuffer.hlsl |  9 ++++----
 3 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/clang/lib/CodeGen/CGHLSLRuntime.cpp b/clang/lib/CodeGen/CGHLSLRuntime.cpp
index d3d9d426643596..128ca86f66b5aa 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -130,8 +130,11 @@ CGHLSLRuntime::getOrCalculateStructSizeForBuffer(llvm::StructType *StructTy) {
   size_t StructSize = 0;
   LayoutItems.push_back(nullptr); // reserve one slot for the buffer size
 
-  for (llvm::Type *ElTy : StructTy->elements())
-    addLayoutInfoForBufferElement(StructSize, LayoutItems, ElTy);
+  for (llvm::Type *ElTy : StructTy->elements()) {
+    size_t Offset = calculateBufferElementOffset(ElTy, &StructSize);
+    // create metadata constant with the element start offset
+    LayoutItems.push_back(getConstIntMetadata(CGM.getLLVMContext(), Offset));
+  }
 
   // set the size of the buffer
   LayoutItems[1] = getConstIntMetadata(Ctx, StructSize);
@@ -147,16 +150,16 @@ CGHLSLRuntime::getOrCalculateStructSizeForBuffer(llvm::StructType *StructTy) {
   return StructSize;
 }
 
-void CGHLSLRuntime::addLayoutInfoForBufferElement(
-    size_t &EndOffset, SmallVector<llvm::Metadata *> &LayoutItems,
-    llvm::Type *LayoutTy, HLSLPackOffsetAttr *PackoffsetAttr) {
+size_t CGHLSLRuntime::calculateBufferElementOffset(
+    llvm::Type *LayoutTy, size_t *LayoutEndOffset,
+    HLSLPackOffsetAttr *PackoffsetAttr) {
 
-  // calculate element offset and size; for arrays also calculate array
-  // element count and stride
+  // calculate element offset and size
   size_t ElemOffset = 0;
   size_t ElemSize = 0;
   size_t ArrayCount = 1;
   size_t ArrayStride = 0;
+  size_t EndOffset = *LayoutEndOffset;
   size_t NextRowOffset = llvm::alignTo(EndOffset, 16U);
 
   if (LayoutTy->isArrayTy()) {
@@ -205,13 +208,9 @@ void CGHLSLRuntime::addLayoutInfoForBufferElement(
   // with packoffset annotations)
   unsigned NewEndOffset =
       ElemOffset + (ArrayCount - 1) * ArrayStride + ElemSize;
-  EndOffset = std::max<size_t>(EndOffset, NewEndOffset);
+  *LayoutEndOffset = std::max<size_t>(EndOffset, NewEndOffset);
 
-  // create metadata constan with the offset and stride and add to list
-  LayoutItems.push_back(getConstIntMetadata(CGM.getLLVMContext(), ElemOffset));
-  if (ArrayStride)
-    LayoutItems.push_back(
-        getConstIntMetadata(CGM.getLLVMContext(), ArrayStride));
+  return ElemOffset;
 }
 
 void CGHLSLRuntime::emitBufferGlobalsAndMetadata(const HLSLBufferDecl *BufDecl,
@@ -284,9 +283,12 @@ void CGHLSLRuntime::emitBufferGlobalsAndMetadata(const HLSLBufferDecl *BufDecl,
               !UsePackoffset) &&
              "expected packoffset attribute on every declaration");
 
-      addLayoutInfoForBufferElement(
-          BufferSize, LayoutItems, LayoutType,
+      size_t Offset = calculateBufferElementOffset(
+          LayoutType, &BufferSize,
           UsePackoffset ? VD->getAttr<HLSLPackOffsetAttr>() : nullptr);
+
+      // create metadata constant with the element start offset
+      LayoutItems.push_back(getConstIntMetadata(CGM.getLLVMContext(), Offset));
     }
   }
   assert(ElemIt == LayoutStruct->element_end() &&
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.h b/clang/lib/CodeGen/CGHLSLRuntime.h
index a6e3c78f522851..d1f678863d4fb7 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.h
+++ b/clang/lib/CodeGen/CGHLSLRuntime.h
@@ -166,9 +166,10 @@ class CGHLSLRuntime {
                                    BufferResBinding &Binding);
   void emitBufferGlobalsAndMetadata(const HLSLBufferDecl *BufDecl,
                                     llvm::GlobalVariable *BufGV);
-  void addLayoutInfoForBufferElement(
-      size_t &EndOffset, SmallVector<llvm::Metadata *> &LayoutItems,
-      llvm::Type *LayoutTy, HLSLPackOffsetAttr *PackoffsetAttr = nullptr);
+
+  size_t
+  calculateBufferElementOffset(llvm::Type *LayoutTy, size_t *LayoutEndOffset,
+                               HLSLPackOffsetAttr *PackoffsetAttr = nullptr);
 
   size_t getOrCalculateStructSizeForBuffer(llvm::StructType *StructTy);
 
diff --git a/clang/test/CodeGenHLSL/cbuffer.hlsl b/clang/test/CodeGenHLSL/cbuffer.hlsl
index 99f16ea62cdcbc..e600d25c4e19cf 100644
--- a/clang/test/CodeGenHLSL/cbuffer.hlsl
+++ b/clang/test/CodeGenHLSL/cbuffer.hlsl
@@ -186,15 +186,14 @@ void main() {
 // CHECK: ![[CBSCALARS_LAYOUT]] = !{!"struct.__cblayout_CBScalars", i32 56, i32 0, i32 8, i32 16, i32 24, i32 32, i32 36, i32 40, i32 48}
 // CHECK: ![[CBVECTORS_LAYOUT]] = !{!"struct.__cblayout_CBVectors", i32 136, i32 0, i32 16, i32 40, i32 48, i32 80, i32 96, i32 112}
                                   
-// CHECK: ![[CBARRAYS_LAYOUT]] = !{!"struct.__cblayout_CBArrays", i32 708, i32 0, i32 16, i32 48, i32 32, i32 112, i32 16, i32 176, i32 16,
-// CHECK-SAME: i32 224, i32 16, i32 608, i32 16, i32 624, i32 16, i32 656, i32 16}
+// CHECK: ![[CBARRAYS_LAYOUT]] = !{!"struct.__cblayout_CBArrays", i32 708, i32 0, i32 48, i32 112, i32 176, i32 224, i32 608, i32 624, i32 656}
 
 // CHECK: ![[A_LAYOUT]] = !{!"struct.A", i32 8, i32 0}
 // CHECK: ![[B_LAYOUT]] = !{!"struct.B", i32 14, i32 0, i32 8}
 // CHECK: ![[C_LAYOUT]] = !{!"struct.C", i32 24, i32 0, i32 16}
-// CHECK: ![[D_LAYOUT]] = !{!"struct.__cblayout_D", i32 94, i32 0, i32 16}
-// CHECK: ![[CBSTRUCTS_LAYOUT]] = !{!"struct.__cblayout_CBStructs", i32 262, i32 0, i32 16, i32 32, i32 64, i32 16, i32 144, i32 238, i32 240, i32 256}
+// CHECK: ![[D_LAYOUT]] = !{!"struct.__cblayout_D", i32 94, i32 0}
+// CHECK: ![[CBSTRUCTS_LAYOUT]] = !{!"struct.__cblayout_CBStructs", i32 262, i32 0, i32 16, i32 32, i32 64, i32 144, i32 238, i32 240, i32 256}
 
 // CHECK: ![[TEST_LAYOUT]] = !{!"struct.Test", i32 8, i32 0, i32 4}
 // CHECK: ![[ANON_LAYOUT]] = !{!"struct.anon", i32 4, i32 0}
-// CHECK: ![[CBMIX_LAYOUT]] = !{!"struct.__cblayout_CBMix", i32 162, i32 0, i32 16, i32 24, i32 32, i32 16, i32 120, i32 128, i32 136, i32 144, i32 152, i32 160}
+// CHECK: ![[CBMIX_LAYOUT]] = !{!"struct.__cblayout_CBMix", i32 162, i32 0, i32 24, i32 32, i32 120, i32 128, i32 136, i32 144, i32 152, i32 160}

>From 749e88e87f36b8b4f2a8b5a4ddf02230a4be9600 Mon Sep 17 00:00:00 2001
From: Helena Kotas <hekotas at microsoft.com>
Date: Tue, 28 Jan 2025 22:02:24 -0800
Subject: [PATCH 3/4] cleanup, update comments

---
 clang/lib/CodeGen/CGHLSLRuntime.cpp   | 188 +++++++++++++-------------
 clang/lib/CodeGen/CGHLSLRuntime.h     |   4 +-
 clang/lib/CodeGen/Targets/DirectX.cpp |   1 -
 clang/test/CodeGenHLSL/cbuffer.hlsl   |   2 +-
 4 files changed, 100 insertions(+), 95 deletions(-)

diff --git a/clang/lib/CodeGen/CGHLSLRuntime.cpp b/clang/lib/CodeGen/CGHLSLRuntime.cpp
index 128ca86f66b5aa..52247173b69901 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -89,8 +89,7 @@ static bool isResourceRecordType(const clang::Type *Ty) {
   return HLSLAttributedResourceType::findHandleTypeOnResource(Ty) != nullptr;
 }
 
-// Returns true if the type is an HLSL resource class or an array of
-// HLSL resource classes
+// Returns true if the type is an HLSL resource class or an array of them
 static bool isResourceRecordTypeOrArrayOf(const clang::Type *Ty) {
   while (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(Ty))
     Ty = CAT->getArrayElementTypeNoTypeQual();
@@ -113,48 +112,56 @@ static unsigned getScalarOrVectorSize(llvm::Type *Ty) {
   return Ty->getScalarSizeInBits() / 8;
 }
 
+// Returns size of a struct in constant buffer layout. The sizes are cached
+// in StructSizesForBuffer map. The map is also an indicator if a layout
+// metadata for this struct has been added to the module.
+// If the struct type is not in the map, this method will calculate the struct
+// layout, add a metadata node describing it to the module, and add the struct
+// size to the map.
 size_t
 CGHLSLRuntime::getOrCalculateStructSizeForBuffer(llvm::StructType *StructTy) {
-  assert(StructTy->isStructTy());
-
   // check if we already have a side for this struct
   auto SizeIt = StructSizesForBuffer.find(StructTy);
   if (SizeIt != StructSizesForBuffer.end())
     return SizeIt->getSecond();
 
-  // if not, calculate the struct layout and add it to metadata
+  // if not, calculate the struct layout and create a metadata node
   LLVMContext &Ctx = CGM.getLLVMContext();
   SmallVector<llvm::Metadata *> LayoutItems;
+
+  // start metadata list with a struct name and reserve one slot for its size
   LayoutItems.push_back(MDString::get(Ctx, StructTy->getName()));
+  LayoutItems.push_back(nullptr);
 
+  // add element offsets
   size_t StructSize = 0;
-  LayoutItems.push_back(nullptr); // reserve one slot for the buffer size
-
   for (llvm::Type *ElTy : StructTy->elements()) {
     size_t Offset = calculateBufferElementOffset(ElTy, &StructSize);
-    // create metadata constant with the element start offset
     LayoutItems.push_back(getConstIntMetadata(CGM.getLLVMContext(), Offset));
   }
-
-  // set the size of the buffer
+  // set the size of the buffer to the reserved slot
   LayoutItems[1] = getConstIntMetadata(Ctx, StructSize);
 
-  // add the struct layout info to metadata
-  MDNode *LayoutMDNode = MDNode::get(CGM.getLLVMContext(), LayoutItems);
+  // add the struct layout to metadata
   CGM.getModule()
       .getOrInsertNamedMetadata("hlsl.cblayouts")
-      ->addOperand(LayoutMDNode);
+      ->addOperand(MDNode::get(CGM.getLLVMContext(), LayoutItems));
 
   // add struct size to list and return it
   StructSizesForBuffer[StructTy] = StructSize;
   return StructSize;
 }
 
+// Calculates offset of a single element in constant buffer layout.
+// The provided LayoutEndOffset marks the end of the layout so far (end offset
+// of the buffer or struct). After the element offset calculations are done it
+// will be updated the new end of layout value.
+// If the PackoffsetAttrs is not nullptr the offset will be based on the
+// packoffset annotation.
 size_t CGHLSLRuntime::calculateBufferElementOffset(
     llvm::Type *LayoutTy, size_t *LayoutEndOffset,
     HLSLPackOffsetAttr *PackoffsetAttr) {
 
-  // calculate element offset and size
   size_t ElemOffset = 0;
   size_t ElemSize = 0;
   size_t ArrayCount = 1;
@@ -198,14 +205,15 @@ size_t CGHLSLRuntime::calculateBufferElementOffset(
       ElemOffset = PackoffsetAttr->getOffsetInBytes();
     } else {
       ElemOffset = llvm::alignTo(EndOffset, Align);
+      // if the element does not fit, move it to the next row
       if (ElemOffset + ElemSize > NextRowOffset)
         ElemOffset = NextRowOffset;
     }
   }
 
   // Update end offset of the buffer/struct layout; do not update it if
-  // the provided EndOffset is already bigger than the new one (which may happen
-  // with packoffset annotations)
+  // the provided EndOffset is already bigger than the new one value
+  // (which may happen with packoffset annotations)
   unsigned NewEndOffset =
       ElemOffset + (ArrayCount - 1) * ArrayStride + ElemSize;
   *LayoutEndOffset = std::max<size_t>(EndOffset, NewEndOffset);
@@ -213,102 +221,106 @@ size_t CGHLSLRuntime::calculateBufferElementOffset(
   return ElemOffset;
 }
 
+// Emits constant global variables for buffer declarations, creates metadata
+// linking the constant globals with the buffer. Also calculates the buffer
+// layout and creates metadata node describing it.
 void CGHLSLRuntime::emitBufferGlobalsAndMetadata(const HLSLBufferDecl *BufDecl,
                                                  llvm::GlobalVariable *BufGV) {
+  LLVMContext &Ctx = CGM.getLLVMContext();
   llvm::StructType *LayoutStruct = cast<llvm::StructType>(
       cast<llvm::TargetExtType>(BufGV->getValueType())->getTypeParameter(0));
 
-  LLVMContext &Ctx = CGM.getLLVMContext();
-
+  // Start metadata list associating the buffer global variable with its
+  // constatns
   SmallVector<llvm::Metadata *> BufGlobals;
   BufGlobals.push_back(ValueAsMetadata::get(BufGV));
 
+  // Start layout metadata list with a struct name and reserve one slot for
+  // the buffer size
   SmallVector<llvm::Metadata *> LayoutItems;
   LayoutItems.push_back(MDString::get(Ctx, LayoutStruct->getName()));
+  LayoutItems.push_back(nullptr);
 
   size_t BufferSize = 0;
-  size_t BufferSizeIndex = LayoutItems.size();
-  LayoutItems.push_back(nullptr); // reserve one slot for the buffer size
-
   bool UsePackoffset = BufDecl->hasPackoffset();
-
   const auto *ElemIt = LayoutStruct->element_begin();
   for (Decl *D : BufDecl->decls()) {
     if (isa<CXXRecordDecl, EmptyDecl>(D))
       // Nothing to do for this declaration.
       continue;
     if (isa<FunctionDecl>(D)) {
-      // A function within an cbuffer is effectively a top-level function,
-      // as it only refers to globally scoped declarations.
+      // A function within an cbuffer is effectively a top-level function.
       CGM.EmitTopLevelDecl(D);
       continue;
     }
-    if (VarDecl *VD = dyn_cast<VarDecl>(D)) {
-      QualType VDTy = VD->getType();
-      if (VDTy.getAddressSpace() != LangAS::hlsl_constant) {
-        if (VD->getStorageClass() == SC_Static ||
-            isResourceRecordTypeOrArrayOf(VDTy.getTypePtr())) {
-          // Emit static variables and resource classes inside cbuffer as
-          // regular globals
-          CGM.EmitGlobal(VD);
-        }
-        // Anything else that is not in the hlsl_constant address space must be
-        // an empty struct or a zero-sized array and can be ignored
-        continue;
-      }
+    VarDecl *VD = dyn_cast<VarDecl>(D);
+    if (!VD)
+      continue;
 
-      assert(ElemIt != LayoutStruct->element_end() &&
-             "number of elements in layout struct does not match");
-      llvm::Type *LayoutType = *ElemIt++;
-
-      assert((CGM.getTypes().ConvertTypeForMem(VDTy) == LayoutType ||
-              (LayoutType->isStructTy() &&
-               cast<llvm::StructType>(LayoutType)
-                   ->getName()
-                   .starts_with(("struct.__cblayout_" +
-                                 VDTy->getAsCXXRecordDecl()->getName())
-                                    .str()))) &&
-             "layout type does not match the converted element type");
-
-      // handle any resources declarations inside the struct
-      if (VDTy->isStructureType() && VDTy->isHLSLIntangibleType())
-        // FIXME: handle resources in cbuffer structs
-        llvm_unreachable("resources in cbuffer are not supported yet");
-
-      GlobalVariable *ElemGV =
-          cast<GlobalVariable>(CGM.GetAddrOfGlobalVar(VD, LayoutType));
-      BufGlobals.push_back(ValueAsMetadata::get(ElemGV));
-
-      assert(((UsePackoffset && VD->hasAttr<HLSLPackOffsetAttr>()) ||
-              !UsePackoffset) &&
-             "expected packoffset attribute on every declaration");
-
-      size_t Offset = calculateBufferElementOffset(
-          LayoutType, &BufferSize,
-          UsePackoffset ? VD->getAttr<HLSLPackOffsetAttr>() : nullptr);
-
-      // create metadata constant with the element start offset
-      LayoutItems.push_back(getConstIntMetadata(CGM.getLLVMContext(), Offset));
+    QualType VDTy = VD->getType();
+    if (VDTy.getAddressSpace() != LangAS::hlsl_constant) {
+      if (VD->getStorageClass() == SC_Static ||
+          VDTy.getAddressSpace() == LangAS::hlsl_groupshared ||
+          isResourceRecordTypeOrArrayOf(VDTy.getTypePtr())) {
+        // Emit static and groupshared variables and resource classes inside
+        // cbuffer as regular globals
+        CGM.EmitGlobal(VD);
+      }
+      // Anything else that is not in the hlsl_constant address space must be
+      // an empty struct or a zero-sized array and can be ignored
+      continue;
     }
+
+    assert(ElemIt != LayoutStruct->element_end() &&
+           "number of elements in layout struct does not match");
+    llvm::Type *LayoutType = *ElemIt++;
+
+    // Make sure the type of the VarDecl type matches the type of the layout
+    // struct element, or that it is a layout struct with the same name
+    assert((CGM.getTypes().ConvertTypeForMem(VDTy) == LayoutType ||
+            (LayoutType->isStructTy() &&
+             cast<llvm::StructType>(LayoutType)
+                 ->getName()
+                 .starts_with(("struct.__cblayout_" +
+                               VDTy->getAsCXXRecordDecl()->getName())
+                                  .str()))) &&
+           "layout type does not match the converted element type");
+
+    // there might be resources inside the used defined structs
+    if (VDTy->isStructureType() && VDTy->isHLSLIntangibleType())
+      // FIXME: handle resources in cbuffer structs
+      llvm_unreachable("resources in cbuffer are not supported yet");
+
+    // create global variable for the constant and to metadata list
+    GlobalVariable *ElemGV =
+        cast<GlobalVariable>(CGM.GetAddrOfGlobalVar(VD, LayoutType));
+    BufGlobals.push_back(ValueAsMetadata::get(ElemGV));
+
+    // get offset of the global and and to metadata list
+    assert(((UsePackoffset && VD->hasAttr<HLSLPackOffsetAttr>()) ||
+            !UsePackoffset) &&
+           "expected packoffset attribute on every declaration");
+    size_t Offset = calculateBufferElementOffset(
+        LayoutType, &BufferSize,
+        UsePackoffset ? VD->getAttr<HLSLPackOffsetAttr>() : nullptr);
+    LayoutItems.push_back(getConstIntMetadata(Ctx, Offset));
   }
   assert(ElemIt == LayoutStruct->element_end() &&
          "number of elements in layout struct does not match");
-
-  // add buffer global and a list of its constants to metadata
-  MDNode *BufMDNode = MDNode::get(CGM.getLLVMContext(), BufGlobals);
-  CGM.getModule().getOrInsertNamedMetadata("hlsl.cbs")->addOperand(BufMDNode);
-
   // set the size of the buffer
-  LayoutItems[BufferSizeIndex] = getConstIntMetadata(Ctx, BufferSize);
+  LayoutItems[1] = getConstIntMetadata(Ctx, BufferSize);
+
+  // add buffer metadata to the module
+  CGM.getModule()
+      .getOrInsertNamedMetadata("hlsl.cbs")
+      ->addOperand(MDNode::get(Ctx, BufGlobals));
 
-  // add buffer layout to metadata
-  MDNode *LayoutMDNode = MDNode::get(CGM.getLLVMContext(), LayoutItems);
   CGM.getModule()
       .getOrInsertNamedMetadata("hlsl.cblayouts")
-      ->addOperand(LayoutMDNode);
+      ->addOperand(MDNode::get(Ctx, LayoutItems));
 }
 
-// Creates resource handle type for the HLSL buffer
+// Creates resource handle type for the HLSL buffer declaration
 static const clang::HLSLAttributedResourceType *
 createBufferHandleType(const HLSLBufferDecl *BufDecl) {
   ASTContext &AST = BufDecl->getASTContext();
@@ -319,26 +331,20 @@ createBufferHandleType(const HLSLBufferDecl *BufDecl) {
   return cast<HLSLAttributedResourceType>(QT.getTypePtr());
 }
 
-// Creates temporary global variables for all declarations within the constant
-// buffer context, creates a global variable for the constant buffer and adds
-// it to the module.
-// All uses of the temporary constant globals will be replaced with buffer
-// access intrinsic resource.getpointer in CGHLSLRuntime::finishCodeGen.
-// Later on in DXILResourceAccess pass these will be transtaled
-// to dx.op.cbufferLoadLegacy instructions.
+// Codegen for HLSLBufferDecl
 void CGHLSLRuntime::addBuffer(const HLSLBufferDecl *BufDecl) {
 
   assert(BufDecl->isCBuffer() && "tbuffer codegen is not supported yet");
 
-  // Create resource handle type for the buffer
+  // create resource handle type for the buffer
   const clang::HLSLAttributedResourceType *ResHandleTy =
       createBufferHandleType(BufDecl);
 
-  // ignore empty constant buffer
+  // empty constant buffer is ignored
   if (ResHandleTy->getContainedType()->getAsCXXRecordDecl()->isEmpty())
     return;
 
-  // Create global variable for the buffer
+  // create global variable for the constant buffer
   llvm::Module &M = CGM.getModule();
   llvm::TargetExtType *TargetTy =
       cast<llvm::TargetExtType>(convertHLSLSpecificType(ResHandleTy));
@@ -350,10 +356,10 @@ void CGHLSLRuntime::addBuffer(const HLSLBufferDecl *BufDecl) {
                          GlobalValue::NotThreadLocal);
   M.insertGlobalVariable(BufGV);
 
-  // Add globals for buffer elements and create metadata node for the buffer
+  // Add globals for constant buffer elements and create metadata nodes
   emitBufferGlobalsAndMetadata(BufDecl, BufGV);
 
-  // Add cbuffer resource initialization
+  // Resource initialization
   const HLSLResourceBindingAttr *RBA =
       BufDecl->getAttr<HLSLResourceBindingAttr>();
   // FIXME: handle implicit binding if no binding attribute is found
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.h b/clang/lib/CodeGen/CGHLSLRuntime.h
index d1f678863d4fb7..8658cb8653fb46 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.h
+++ b/clang/lib/CodeGen/CGHLSLRuntime.h
@@ -71,7 +71,6 @@ class FunctionDecl;
 namespace CodeGen {
 
 class CodeGenModule;
-class CGBuilderTy;
 
 class CGHLSLRuntime {
 public:
@@ -175,7 +174,8 @@ class CGHLSLRuntime {
 
   llvm::Triple::ArchType getArch();
 
-  // sizes of structs that in constant buffer layout
+  // Sizes of structs in constant buffer layout. Structs in the map
+  // had their layout calculated and added to the module as metadata.
   llvm::DenseMap<llvm::StructType *, size_t> StructSizesForBuffer;
 };
 
diff --git a/clang/lib/CodeGen/Targets/DirectX.cpp b/clang/lib/CodeGen/Targets/DirectX.cpp
index 33bddc56d83f24..ec7fa342d58468 100644
--- a/clang/lib/CodeGen/Targets/DirectX.cpp
+++ b/clang/lib/CodeGen/Targets/DirectX.cpp
@@ -44,7 +44,6 @@ llvm::Type *DirectXTargetCodeGenInfo::getHLSLType(CodeGenModule &CGM,
       return nullptr;
 
     // convert element type
-    // llvm::Type *ElemType = CGM.getTypes().ConvertTypeForMem(ContainedTy);
     llvm::Type *ElemType = CGM.getTypes().ConvertType(ContainedTy);
 
     llvm::StringRef TypeName =
diff --git a/clang/test/CodeGenHLSL/cbuffer.hlsl b/clang/test/CodeGenHLSL/cbuffer.hlsl
index e600d25c4e19cf..9a3f632e859c76 100644
--- a/clang/test/CodeGenHLSL/cbuffer.hlsl
+++ b/clang/test/CodeGenHLSL/cbuffer.hlsl
@@ -164,6 +164,7 @@ void main() {
 // CHECK-NEXT: call void @_init_resource_CBArrays.cb()
 
 // CHECK: !hlsl.cbs = !{![[CBSCALARS:[0-9]+]], ![[CBVECTORS:[0-9]+]], ![[CBARRAYS:[0-9]+]], ![[CBSTRUCTS:[0-9]+]], ![[CBMIX:[0-9]+]]}
+
 // CHECK: !hlsl.cblayouts = !{![[CBSCALARS_LAYOUT:[0-9]+]], ![[CBVECTORS_LAYOUT:[0-9]+]], ![[CBARRAYS_LAYOUT:[0-9]+]], ![[A_LAYOUT:[0-9]+]],
 // CHECK-SAME: ![[B_LAYOUT:[0-9]+]], ![[C_LAYOUT:[0-9]+]], ![[D_LAYOUT:[0-9]+]], ![[CBSTRUCTS_LAYOUT:[0-9]+]], ![[TEST_LAYOUT:[0-9]+]],
 // CHECK-SAME: ![[ANON_LAYOUT:[0-9]+]], ![[CBMIX_LAYOUT:[0-9]+]]}
@@ -193,7 +194,6 @@ void main() {
 // CHECK: ![[C_LAYOUT]] = !{!"struct.C", i32 24, i32 0, i32 16}
 // CHECK: ![[D_LAYOUT]] = !{!"struct.__cblayout_D", i32 94, i32 0}
 // CHECK: ![[CBSTRUCTS_LAYOUT]] = !{!"struct.__cblayout_CBStructs", i32 262, i32 0, i32 16, i32 32, i32 64, i32 144, i32 238, i32 240, i32 256}
-
 // CHECK: ![[TEST_LAYOUT]] = !{!"struct.Test", i32 8, i32 0, i32 4}
 // CHECK: ![[ANON_LAYOUT]] = !{!"struct.anon", i32 4, i32 0}
 // CHECK: ![[CBMIX_LAYOUT]] = !{!"struct.__cblayout_CBMix", i32 162, i32 0, i32 24, i32 32, i32 120, i32 128, i32 136, i32 144, i32 152, i32 160}

>From 66ae78472080bb2b9de4b99ff63b5219f14c75c8 Mon Sep 17 00:00:00 2001
From: Helena Kotas <hekotas at microsoft.com>
Date: Tue, 4 Feb 2025 17:58:43 -0800
Subject: [PATCH 4/4] Add LayoutStruct to HLSLBufferDecl; add skipping of
 implicit initializers

---
 clang/include/clang/AST/Decl.h |  5 ++++-
 clang/lib/AST/Decl.cpp         | 15 +++++----------
 clang/lib/Sema/SemaDecl.cpp    |  6 ++++++
 clang/lib/Sema/SemaHLSL.cpp    |  2 +-
 4 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index e1c7e3817699ce..05e56978977f2b 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -5035,6 +5035,8 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
   /// HasValidPackoffset - Whether the buffer has valid packoffset annotations
   //                       on all declarations
   bool HasPackoffset;
+  // LayoutStruct - Layout struct for the buffer
+  CXXRecordDecl *LayoutStruct;
 
   HLSLBufferDecl(DeclContext *DC, bool CBuffer, SourceLocation KwLoc,
                  IdentifierInfo *ID, SourceLocation IDLoc,
@@ -5057,7 +5059,8 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
   bool isCBuffer() const { return IsCBuffer; }
   void setHasPackoffset(bool PO) { HasPackoffset = PO; }
   bool hasPackoffset() const { return HasPackoffset; }
-  const CXXRecordDecl *getLayoutStruct() const;
+  const CXXRecordDecl *getLayoutStruct() const { return LayoutStruct; }
+  void addLayoutStruct(CXXRecordDecl *LS);
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index fa7d03354a9937..4c5201d0ba2ee9 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -5717,7 +5717,7 @@ 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), HasPackoffset(false) {}
+      IsCBuffer(CBuffer), HasPackoffset(false), LayoutStruct(nullptr) {}
 
 HLSLBufferDecl *HLSLBufferDecl::Create(ASTContext &C,
                                        DeclContext *LexicalParent, bool CBuffer,
@@ -5747,15 +5747,10 @@ HLSLBufferDecl *HLSLBufferDecl::CreateDeserialized(ASTContext &C,
                                     SourceLocation(), SourceLocation());
 }
 
-const CXXRecordDecl *HLSLBufferDecl::getLayoutStruct() const {
-  // Layout struct is the last decl in the HLSLBufferDecl.
-  if (CXXRecordDecl *RD = llvm::dyn_cast_or_null<CXXRecordDecl>(LastDecl)) {
-    assert(RD->getName().starts_with(
-               ("__cblayout_" + getIdentifier()->getName()).str()) &&
-           "expected buffer layout struct");
-    return RD;
-  }
-  llvm_unreachable("HLSL buffer is missing a layout struct");
+void HLSLBufferDecl::addLayoutStruct(CXXRecordDecl *LS) {
+  assert(LayoutStruct == nullptr && "layout struct has already been set");
+  LayoutStruct = LS;
+  addDecl(LS);
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 7c70150871da90..5497c30ed09ffd 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -14184,6 +14184,12 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
         Var->getType().getAddressSpace() == LangAS::opencl_local)
       return;
 
+    // In HLSL, objects in the hlsl_constant address space are initialized
+    // externally, so don't synthesize an implicit initializer.
+    if (getLangOpts().HLSL &&
+        Var->getType().getAddressSpace() == LangAS::hlsl_constant)
+      return;
+
     // C++03 [dcl.init]p9:
     //   If no initializer is specified for an object, and the
     //   object is of (possibly cv-qualified) non-POD class type (or
diff --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp
index 2807cc773320b2..d80e605055ad72 100644
--- a/clang/lib/Sema/SemaHLSL.cpp
+++ b/clang/lib/Sema/SemaHLSL.cpp
@@ -502,7 +502,7 @@ void createHostLayoutStructForBuffer(Sema &S, HLSLBufferDecl *BufDecl) {
     }
   }
   LS->completeDefinition();
-  BufDecl->addDecl(LS);
+  BufDecl->addLayoutStruct(LS);
 }
 
 // Handle end of cbuffer/tbuffer declaration



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