[HLSL] Implicit resource binding for cbuffers

clang/include/clang/Basic/Attr.td

@@ -4778,6 +4778,7 @@ def HLSLResourceBinding: InheritableAttr {
       RegisterType RegType;
       std::optional<unsigned> SlotNumber;
       unsigned SpaceNumber;
+      std::optional<unsigned> ImplicitBindingOrderID;
 
   public:
       void setBinding(RegisterType RT, std::optional<unsigned> SlotNum, unsigned SpaceNum) {
@@ -4799,6 +4800,16 @@ def HLSLResourceBinding: InheritableAttr {
       unsigned getSpaceNumber() const {
         return SpaceNumber;
       }
+      void setImplicitBindingOrderID(uint32_t Value) {
+        ImplicitBindingOrderID = Value;
+      }
+      bool hasImplicitBindingOrderID() const { 
+        return ImplicitBindingOrderID.has_value();
+      }
+      uint32_t getImplicitBindingOrderID() const {
+        assert(hasImplicitBindingOrderID() && "attribute does not have implicit binding order id");
+        return ImplicitBindingOrderID.value();
+      }
   }];
 }
 

clang/include/clang/Basic/Builtins.td

@@ -4819,6 +4819,12 @@ def HLSLResourceHandleFromBinding : LangBuiltin<"HLSL_LANG"> {
   let Prototype = "void(...)";
 }
 
+def HLSLResourceHandleFromImplicitBinding : LangBuiltin<"HLSL_LANG"> {
+  let Spellings = ["__builtin_hlsl_resource_handlefromimplicitbinding"];
+  let Attributes = [NoThrow];
+  let Prototype = "void(...)";
+}
+
 def HLSLAll : LangBuiltin<"HLSL_LANG"> {
   let Spellings = ["__builtin_hlsl_all"];
   let Attributes = [NoThrow, Const];

clang/include/clang/Sema/SemaHLSL.h

@@ -174,13 +174,20 @@ class SemaHLSL : public SemaBase {
   // buffer which will be created at the end of the translation unit.
   llvm::SmallVector<Decl *> DefaultCBufferDecls;
 
+  uint32_t ImplicitBindingNextOrderID = 0;
+
 private:
   void collectResourceBindingsOnVarDecl(VarDecl *D);
   void collectResourceBindingsOnUserRecordDecl(const VarDecl *VD,
                                                const RecordType *RT);
   void processExplicitBindingsOnDecl(VarDecl *D);
 
   void diagnoseAvailabilityViolations(TranslationUnitDecl *TU);
+
+  bool initGlobalResourceDecl(VarDecl *VD);
+  uint32_t getNextImplicitBindingOrderID() {
+    return ImplicitBindingNextOrderID++;
+  }
 };
 
 } // namespace clang

clang/lib/CodeGen/CGHLSLBuiltins.cpp

@@ -303,6 +303,21 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
         HandleTy, CGM.getHLSLRuntime().getCreateHandleFromBindingIntrinsic(),
         ArrayRef<Value *>{SpaceOp, RegisterOp, RangeOp, IndexOp, NonUniform});
   }
+  case Builtin::BI__builtin_hlsl_resource_handlefromimplicitbinding: {
+    llvm::Type *HandleTy = CGM.getTypes().ConvertType(E->getType());
+    Value *SpaceOp = EmitScalarExpr(E->getArg(1));
+    Value *RangeOp = EmitScalarExpr(E->getArg(2));
+    Value *IndexOp = EmitScalarExpr(E->getArg(3));
+    Value *OrderID = EmitScalarExpr(E->getArg(4));
+    // FIXME: NonUniformResourceIndex bit is not yet implemented
+    // (llvm/llvm-project#135452)
+    Value *NonUniform =
+        llvm::ConstantInt::get(llvm::Type::getInt1Ty(getLLVMContext()), false);
+    return Builder.CreateIntrinsic(
+        HandleTy,
+        CGM.getHLSLRuntime().getCreateHandleFromImplicitBindingIntrinsic(),
+        ArrayRef<Value *>{OrderID, SpaceOp, RangeOp, IndexOp, NonUniform});
+  }
   case Builtin::BI__builtin_hlsl_all: {
     Value *Op0 = EmitScalarExpr(E->getArg(0));
     return Builder.CreateIntrinsic(

clang/lib/CodeGen/CGHLSLRuntime.cpp

@@ -23,6 +23,7 @@
 #include "clang/AST/Type.h"
 #include "clang/Basic/TargetOptions.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/LLVMContext.h"
@@ -42,8 +43,8 @@ using namespace llvm;
 using llvm::hlsl::CBufferRowSizeInBytes;
 
 static void initializeBufferFromBinding(CodeGenModule &CGM,
-                                        llvm::GlobalVariable *GV, unsigned Slot,
-                                        unsigned Space);
+                                        llvm::GlobalVariable *GV,
+                                        HLSLResourceBindingAttr *RBA);
 
 namespace {
 
@@ -257,13 +258,10 @@ void CGHLSLRuntime::addBuffer(const HLSLBufferDecl *BufDecl) {
   emitBufferGlobalsAndMetadata(BufDecl, BufGV);
 
   // Initialize cbuffer from binding (implicit or explicit)
-  const HLSLResourceBindingAttr *RBA =
-      BufDecl->getAttr<HLSLResourceBindingAttr>();
-  // FIXME: handle implicit binding if no binding attribute is found
-  // (llvm/llvm-project#110722)
-  if (RBA && RBA->hasRegisterSlot())
-    initializeBufferFromBinding(CGM, BufGV, RBA->getSlotNumber(),
-                                RBA->getSpaceNumber());
+  HLSLResourceBindingAttr *RBA = BufDecl->getAttr<HLSLResourceBindingAttr>();
+  assert(RBA &&
+         "cbuffer/tbuffer should always have resource binding attribute");
+  initializeBufferFromBinding(CGM, BufGV, RBA);
 }
 
 llvm::TargetExtType *
@@ -539,19 +537,27 @@ static void initializeBuffer(CodeGenModule &CGM, llvm::GlobalVariable *GV,
 }
 
 static void initializeBufferFromBinding(CodeGenModule &CGM,
-                                        llvm::GlobalVariable *GV, unsigned Slot,
-                                        unsigned Space) {
+                                        llvm::GlobalVariable *GV,
+                                        HLSLResourceBindingAttr *RBA) {
   llvm::Type *Int1Ty = llvm::Type::getInt1Ty(CGM.getLLVMContext());
-  llvm::Value *Args[] = {
-      llvm::ConstantInt::get(CGM.IntTy, Space), /* reg_space */
-      llvm::ConstantInt::get(CGM.IntTy, Slot),  /* lower_bound */
-      llvm::ConstantInt::get(CGM.IntTy, 1),     /* range_size */
-      llvm::ConstantInt::get(CGM.IntTy, 0),     /* index */
-      llvm::ConstantInt::get(Int1Ty, false)     /* non-uniform */
-  };
-  initializeBuffer(CGM, GV,
-                   CGM.getHLSLRuntime().getCreateHandleFromBindingIntrinsic(),
-                   Args);
+  auto *False = llvm::ConstantInt::get(Int1Ty, false);
+  auto *Zero = llvm::ConstantInt::get(CGM.IntTy, 0);
+  auto *One = llvm::ConstantInt::get(CGM.IntTy, 1);
+  auto *Space =
+      llvm::ConstantInt::get(CGM.IntTy, RBA ? RBA->getSpaceNumber() : 0);
+
+  if (RBA->hasRegisterSlot()) {
+    auto *RegSlot = llvm::ConstantInt::get(CGM.IntTy, RBA->getSlotNumber());
+    Intrinsic::ID Intr =
+        CGM.getHLSLRuntime().getCreateHandleFromBindingIntrinsic();
+    initializeBuffer(CGM, GV, Intr, {Space, RegSlot, One, Zero, False});
+  } else {
+    auto *OrderID =
+        llvm::ConstantInt::get(CGM.IntTy, RBA->getImplicitBindingOrderID());
+    Intrinsic::ID Intr =
+        CGM.getHLSLRuntime().getCreateHandleFromImplicitBindingIntrinsic();
+    initializeBuffer(CGM, GV, Intr, {OrderID, Space, One, Zero, False});
+  }
 }
 
 llvm::Instruction *CGHLSLRuntime::getConvergenceToken(BasicBlock &BB) {

clang/lib/CodeGen/CGHLSLRuntime.h

@@ -119,6 +119,8 @@ class CGHLSLRuntime {
                                    resource_getpointer)
   GENERATE_HLSL_INTRINSIC_FUNCTION(CreateHandleFromBinding,
                                    resource_handlefrombinding)
+  GENERATE_HLSL_INTRINSIC_FUNCTION(CreateHandleFromImplicitBinding,
+                                   resource_handlefromimplicitbinding)
   GENERATE_HLSL_INTRINSIC_FUNCTION(BufferUpdateCounter, resource_updatecounter)
   GENERATE_HLSL_INTRINSIC_FUNCTION(GroupMemoryBarrierWithGroupSync,
                                    group_memory_barrier_with_group_sync)

clang/lib/Sema/HLSLBuiltinTypeDeclBuilder.cpp

@@ -668,6 +668,26 @@ BuiltinTypeDeclBuilder::addHandleConstructorFromBinding() {
       .finalize();
 }
 
+BuiltinTypeDeclBuilder &
+BuiltinTypeDeclBuilder::addHandleConstructorFromImplicitBinding() {
+  if (Record->isCompleteDefinition())
+    return *this;
+
+  using PH = BuiltinTypeMethodBuilder::PlaceHolder;
+  ASTContext &AST = SemaRef.getASTContext();
+  QualType HandleType = getResourceHandleField()->getType();
+
+  return BuiltinTypeMethodBuilder(*this, "", AST.VoidTy, false, true)
+      .addParam("spaceNo", AST.UnsignedIntTy)
+      .addParam("range", AST.IntTy)
+      .addParam("index", AST.UnsignedIntTy)
+      .addParam("order_id", AST.UnsignedIntTy)
+      .callBuiltin("__builtin_hlsl_resource_handlefromimplicitbinding",
+                   HandleType, PH::Handle, PH::_0, PH::_1, PH::_2, PH::_3)
+      .assign(PH::Handle, PH::LastStmt)
+      .finalize();
+}
+
 BuiltinTypeDeclBuilder &BuiltinTypeDeclBuilder::addArraySubscriptOperators() {
   ASTContext &AST = Record->getASTContext();
   DeclarationName Subscript =

clang/lib/Sema/HLSLBuiltinTypeDeclBuilder.h

@@ -76,9 +76,10 @@ class BuiltinTypeDeclBuilder {
                   AccessSpecifier Access = AccessSpecifier::AS_private);
   BuiltinTypeDeclBuilder &addArraySubscriptOperators();
 
-  // Builtin types methods
+  // Builtin types constructors
   BuiltinTypeDeclBuilder &addDefaultHandleConstructor();
   BuiltinTypeDeclBuilder &addHandleConstructorFromBinding();
+  BuiltinTypeDeclBuilder &addHandleConstructorFromImplicitBinding();
 
   // Builtin types methods
   BuiltinTypeDeclBuilder &addLoadMethods();

clang/lib/Sema/HLSLExternalSemaSource.cpp

@@ -132,7 +132,8 @@ static BuiltinTypeDeclBuilder setupBufferType(CXXRecordDecl *Decl, Sema &S,
   return BuiltinTypeDeclBuilder(S, Decl)
       .addHandleMember(RC, IsROV, RawBuffer)
       .addDefaultHandleConstructor()
-      .addHandleConstructorFromBinding();
+      .addHandleConstructorFromBinding()
+      .addHandleConstructorFromImplicitBinding();
 }
 
 // This function is responsible for constructing the constraint expression for

clang/lib/Sema/SemaHLSL.cpp

@@ -536,6 +536,18 @@ void createHostLayoutStructForBuffer(Sema &S, HLSLBufferDecl *BufDecl) {
   BufDecl->addLayoutStruct(LS);
 }
 
+static void addImplicitBindingAttrToBuffer(Sema &S, HLSLBufferDecl *BufDecl,
+                                           uint32_t ImplicitBindingOrderID) {
+  RegisterType RT =
+      BufDecl->isCBuffer() ? RegisterType::CBuffer : RegisterType::SRV;
+  auto *Attr =
+      HLSLResourceBindingAttr::CreateImplicit(S.getASTContext(), "", "0", {});
+  std::optional<unsigned> RegSlot;
+  Attr->setBinding(RT, RegSlot, 0);
+  Attr->setImplicitBindingOrderID(ImplicitBindingOrderID);
+  BufDecl->addAttr(Attr);
+}
+
 // Handle end of cbuffer/tbuffer declaration
 void SemaHLSL::ActOnFinishBuffer(Decl *Dcl, SourceLocation RBrace) {
   auto *BufDecl = cast<HLSLBufferDecl>(Dcl);
@@ -546,9 +558,17 @@ void SemaHLSL::ActOnFinishBuffer(Decl *Dcl, SourceLocation RBrace) {
   // create buffer layout struct
   createHostLayoutStructForBuffer(SemaRef, BufDecl);
 
-  if (std::none_of(Dcl->attr_begin(), Dcl->attr_end(),
-                   [](Attr *A) { return isa<HLSLResourceBindingAttr>(A); }))
+  HLSLResourceBindingAttr *RBA = Dcl->getAttr<HLSLResourceBindingAttr>();
+  if (!RBA || !RBA->hasRegisterSlot()) {
     SemaRef.Diag(Dcl->getLocation(), diag::warn_hlsl_implicit_binding);
+    // Use HLSLResourceBindingAttr to transfer implicit binding order_ID
+    // to codegen. If it does not exist, create an implicit attribute.
+    uint32_t OrderID = getNextImplicitBindingOrderID();
+    if (RBA)
+      RBA->setImplicitBindingOrderID(OrderID);
+    else
+      addImplicitBindingAttrToBuffer(SemaRef, BufDecl, OrderID);
+  }
 
   SemaRef.PopDeclContext();
 }
@@ -1972,6 +1992,8 @@ void SemaHLSL::ActOnEndOfTranslationUnit(TranslationUnitDecl *TU) {
     HLSLBufferDecl *DefaultCBuffer = HLSLBufferDecl::CreateDefaultCBuffer(
         SemaRef.getASTContext(), SemaRef.getCurLexicalContext(),
         DefaultCBufferDecls);
+    addImplicitBindingAttrToBuffer(SemaRef, DefaultCBuffer,
+                                   getNextImplicitBindingOrderID());
     SemaRef.getCurLexicalContext()->addDecl(DefaultCBuffer);
     createHostLayoutStructForBuffer(SemaRef, DefaultCBuffer);
 
@@ -2427,6 +2449,20 @@ bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
     TheCall->setType(ResourceTy);
     break;
   }
+  case Builtin::BI__builtin_hlsl_resource_handlefromimplicitbinding: {
+    ASTContext &AST = SemaRef.getASTContext();
+    if (SemaRef.checkArgCount(TheCall, 5) ||
+        CheckResourceHandle(&SemaRef, TheCall, 0) ||
+        CheckArgTypeMatches(&SemaRef, TheCall->getArg(1), AST.UnsignedIntTy) ||
+        CheckArgTypeMatches(&SemaRef, TheCall->getArg(2), AST.IntTy) ||
+        CheckArgTypeMatches(&SemaRef, TheCall->getArg(3), AST.UnsignedIntTy) ||
+        CheckArgTypeMatches(&SemaRef, TheCall->getArg(4), AST.UnsignedIntTy))
+      return true;
+    // use the type of the handle (arg0) as a return type
+    QualType ResourceTy = TheCall->getArg(0)->getType();
+    TheCall->setType(ResourceTy);
+    break;
+  }
   case Builtin::BI__builtin_hlsl_and:
   case Builtin::BI__builtin_hlsl_or: {
     if (SemaRef.checkArgCount(TheCall, 2))
@@ -3258,8 +3294,10 @@ static bool initVarDeclWithCtor(Sema &S, VarDecl *VD,
       VD->getLocation(), SourceLocation(), SourceLocation());
 
   InitializationSequence InitSeq(S, Entity, Kind, Args);
-  ExprResult Init = InitSeq.Perform(S, Entity, Kind, Args);
+  if (InitSeq.Failed())
+    return false;
 
+  ExprResult Init = InitSeq.Perform(S, Entity, Kind, Args);
   if (!Init.get())
     return false;
 
@@ -3269,27 +3307,42 @@ static bool initVarDeclWithCtor(Sema &S, VarDecl *VD,
   return true;
 }
 
-static bool initGlobalResourceDecl(Sema &S, VarDecl *VD) {
+bool SemaHLSL::initGlobalResourceDecl(VarDecl *VD) {
+  std::optional<uint32_t> RegisterSlot;
+  uint32_t SpaceNo = 0;
   HLSLResourceBindingAttr *RBA = VD->getAttr<HLSLResourceBindingAttr>();
-  if (!RBA || !RBA->hasRegisterSlot())
-    // FIXME: add support for implicit binding (llvm/llvm-project#110722)
-    return false;
+  if (RBA) {
+    if (RBA->hasRegisterSlot())
+      RegisterSlot = RBA->getSlotNumber();
+    SpaceNo = RBA->getSpaceNumber();
+  }
 
-  ASTContext &AST = S.getASTContext();
+  ASTContext &AST = SemaRef.getASTContext();
   uint64_t UIntTySize = AST.getTypeSize(AST.UnsignedIntTy);
   uint64_t IntTySize = AST.getTypeSize(AST.IntTy);
-  Expr *Args[] = {
-      IntegerLiteral::Create(AST, llvm::APInt(UIntTySize, RBA->getSlotNumber()),
-                             AST.UnsignedIntTy, SourceLocation()),
-      IntegerLiteral::Create(AST,
-                             llvm::APInt(UIntTySize, RBA->getSpaceNumber()),
-                             AST.UnsignedIntTy, SourceLocation()),
-      IntegerLiteral::Create(AST, llvm::APInt(IntTySize, 1), AST.IntTy,
-                             SourceLocation()),
-      IntegerLiteral::Create(AST, llvm::APInt(UIntTySize, 0), AST.UnsignedIntTy,
-                             SourceLocation())};
-
-  return initVarDeclWithCtor(S, VD, Args);
+  IntegerLiteral *One = IntegerLiteral::Create(AST, llvm::APInt(IntTySize, 1),
+                                               AST.IntTy, SourceLocation());
+  IntegerLiteral *Zero = IntegerLiteral::Create(
+      AST, llvm::APInt(UIntTySize, 0), AST.UnsignedIntTy, SourceLocation());
+  IntegerLiteral *Space =
+      IntegerLiteral::Create(AST, llvm::APInt(UIntTySize, SpaceNo),
+                             AST.UnsignedIntTy, SourceLocation());
+
+  // resource with explicit binding
+  if (RegisterSlot.has_value()) {
+    IntegerLiteral *RegSlot = IntegerLiteral::Create(
+        AST, llvm::APInt(UIntTySize, RegisterSlot.value()), AST.UnsignedIntTy,
+        SourceLocation());
+    Expr *Args[] = {RegSlot, Space, One, Zero};
+    return initVarDeclWithCtor(SemaRef, VD, Args);
+  }
+
+  // resource with explicit binding
+  IntegerLiteral *OrderId = IntegerLiteral::Create(
+      AST, llvm::APInt(UIntTySize, getNextImplicitBindingOrderID()),
+      AST.UnsignedIntTy, SourceLocation());
+  Expr *Args[] = {Space, One, Zero, OrderId};
+  return initVarDeclWithCtor(SemaRef, VD, Args);
 }
 
 // Returns true if the initialization has been handled.
@@ -3307,8 +3360,9 @@ bool SemaHLSL::ActOnUninitializedVarDecl(VarDecl *VD) {
   // FIXME: We currectly support only simple resources - no arrays of resources
   // or resources in user defined structs.
   // (llvm/llvm-project#133835, llvm/llvm-project#133837)
-  if (VD->getType()->isHLSLResourceRecord())
-    return initGlobalResourceDecl(SemaRef, VD);
+  // Initialize resources at the global scope
+  if (VD->hasGlobalStorage() && VD->getType()->isHLSLResourceRecord())
+    return initGlobalResourceDecl(VD);
 
   return false;
 }

clang/test/AST/HLSL/ByteAddressBuffers-AST.hlsl

@@ -78,5 +78,27 @@ RESOURCE Buffer;
 // CHECK-NEXT: DeclRefExpr {{.*}} 'unsigned int' ParmVar {{.*}} 'index' 'unsigned int'
 // CHECK-NEXT: AlwaysInlineAttr
 
+// Constructor from implicit binding
+
+// CHECK: CXXConstructorDecl {{.*}} [[RESOURCE]] 'void (unsigned int, int, unsigned int, unsigned int)' inline
+// CHECK-NEXT: ParmVarDecl {{.*}} spaceNo 'unsigned int'
+// CHECK-NEXT: ParmVarDecl {{.*}} range 'int'
+// CHECK-NEXT: ParmVarDecl {{.*}} index 'unsigned int'
+// CHECK-NEXT: ParmVarDecl {{.*}} order_id 'unsigned int'
+// CHECK-NEXT: CompoundStmt {{.*}}
+// CHECK-NEXT: BinaryOperator {{.*}} '='
+// CHECK-NEXT: MemberExpr {{.*}} lvalue .__handle
+// CHECK-NEXT: CXXThisExpr {{.*}} 'hlsl::[[RESOURCE]]' lvalue implicit this
+// CHECK-NEXT: CallExpr {{.*}} '__hlsl_resource_t
+// CHECK-NEXT: ImplicitCastExpr {{.*}} <BuiltinFnToFnPtr>
+// CHECK-NEXT: DeclRefExpr {{.*}} '<builtin fn type>' Function {{.*}} '__builtin_hlsl_resource_handlefromimplicitbinding'
+// CHECK-NEXT: MemberExpr {{.*}} lvalue .__handle
+// CHECK-NEXT: CXXThisExpr {{.*}} 'hlsl::[[RESOURCE]]' lvalue implicit this
+// CHECK-NEXT: DeclRefExpr {{.*}} 'unsigned int' ParmVar {{.*}} 'spaceNo' 'unsigned int'
+// CHECK-NEXT: DeclRefExpr {{.*}} 'int' ParmVar {{.*}} 'range' 'int'
+// CHECK-NEXT: DeclRefExpr {{.*}} 'unsigned int' ParmVar {{.*}} 'index' 'unsigned int'
+// CHECK-NEXT: DeclRefExpr {{.*}} 'unsigned int' ParmVar {{.*}} 'order_id' 'unsigned int'
+// CHECK-NEXT: AlwaysInlineAttr
+
 // CHECK-NOSUBSCRIPT-NOT: CXXMethodDecl {{.*}} operator[] 'const element_type &(unsigned int) const'
 // CHECK-NOSUBSCRIPT-NOT: CXXMethodDecl {{.*}} operator[] 'element_type &(unsigned int)'