[HLSL] Static resources (llvm#166880)

This change fixes couple of issues with static resources:
- Enables assignment to static resource or resource array variables (fixes llvm#166458)
- Initializes static resources and resource arrays with default constructor that sets the handle to poison

Author: hekota

clang/lib/CodeGen/CGExpr.cpp

@@ -6356,8 +6356,15 @@ LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
 LValue CodeGenFunction::EmitHLSLArrayAssignLValue(const BinaryOperator *E) {
   // Don't emit an LValue for the RHS because it might not be an LValue
   LValue LHS = EmitLValue(E->getLHS());
+
+  // If the RHS is a global resource array, copy all individual resources
+  // into LHS.
+  if (E->getRHS()->getType()->isHLSLResourceRecordArray())
+    if (CGM.getHLSLRuntime().emitResourceArrayCopy(LHS, E->getRHS(), *this))
+      return LHS;
+
   // In C the RHS of an assignment operator is an RValue.
-  // EmitAggregateAssign takes anan LValue for the RHS. Instead we can call
+  // EmitAggregateAssign takes an LValue for the RHS. Instead we can call
   // EmitInitializationToLValue to emit an RValue into an LValue.
   EmitInitializationToLValue(E->getRHS(), LHS);
   return LHS;

clang/lib/CodeGen/CGHLSLRuntime.cpp

@@ -22,6 +22,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Attrs.inc"
 #include "clang/AST/Decl.h"
+#include "clang/AST/Expr.h"
 #include "clang/AST/HLSLResource.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/AST/Type.h"
@@ -94,6 +95,14 @@ void addRootSignatureMD(llvm::dxbc::RootSignatureVersion RootSigVer,
   RootSignatureValMD->addOperand(MDVals);
 }
 
+// Find array variable declaration from DeclRef expression
+static const ValueDecl *getArrayDecl(const Expr *E) {
+  if (const DeclRefExpr *DRE =
+          dyn_cast_or_null<DeclRefExpr>(E->IgnoreImpCasts()))
+    return DRE->getDecl();
+  return nullptr;
+}
+
 // Find array variable declaration from nested array subscript AST nodes
 static const ValueDecl *getArrayDecl(const ArraySubscriptExpr *ASE) {
   const Expr *E = nullptr;
@@ -103,9 +112,7 @@ static const ValueDecl *getArrayDecl(const ArraySubscriptExpr *ASE) {
       return nullptr;
     ASE = dyn_cast<ArraySubscriptExpr>(E);
   }
-  if (const DeclRefExpr *DRE = dyn_cast_or_null<DeclRefExpr>(E))
-    return DRE->getDecl();
-  return nullptr;
+  return getArrayDecl(E);
 }
 
 // Get the total size of the array, or -1 if the array is unbounded.
@@ -1214,12 +1221,13 @@ std::optional<LValue> CGHLSLRuntime::emitResourceArraySubscriptExpr(
           ArraySubsExpr->getType()->isHLSLResourceRecordArray()) &&
          "expected resource array subscript expression");
 
-  // Let clang codegen handle local resource array subscripts,
+  // Let clang codegen handle local and static resource array subscripts,
   // or when the subscript references on opaque expression (as part of
   // ArrayInitLoopExpr AST node).
   const VarDecl *ArrayDecl =
       dyn_cast_or_null<VarDecl>(getArrayDecl(ArraySubsExpr));
-  if (!ArrayDecl || !ArrayDecl->hasGlobalStorage())
+  if (!ArrayDecl || !ArrayDecl->hasGlobalStorage() ||
+      ArrayDecl->getStorageClass() == SC_Static)
     return std::nullopt;
 
   // get the resource array type
@@ -1249,7 +1257,7 @@ std::optional<LValue> CGHLSLRuntime::emitResourceArraySubscriptExpr(
   // Find binding info for the resource array. For implicit binding
   // an HLSLResourceBindingAttr should have been added by SemaHLSL.
   ResourceBindingAttrs Binding(ArrayDecl);
-  assert((Binding.hasBinding()) &&
+  assert(Binding.hasBinding() &&
          "resource array must have a binding attribute");
 
   // Find the individual resource type.
@@ -1305,6 +1313,49 @@ std::optional<LValue> CGHLSLRuntime::emitResourceArraySubscriptExpr(
   return CGF.MakeAddrLValue(TmpVar, ResultTy, AlignmentSource::Decl);
 }
 
+// If RHSExpr is a global resource array, initialize all of its resources and
+// set them into LHS. Returns false if no copy has been performed and the
+// array copy should be handled by Clang codegen.
+bool CGHLSLRuntime::emitResourceArrayCopy(LValue &LHS, Expr *RHSExpr,
+                                          CodeGenFunction &CGF) {
+  QualType ResultTy = RHSExpr->getType();
+  assert(ResultTy->isHLSLResourceRecordArray() && "expected resource array");
+
+  // Let Clang codegen handle local and static resource array copies.
+  const VarDecl *ArrayDecl = dyn_cast_or_null<VarDecl>(getArrayDecl(RHSExpr));
+  if (!ArrayDecl || !ArrayDecl->hasGlobalStorage() ||
+      ArrayDecl->getStorageClass() == SC_Static)
+    return false;
+
+  // Find binding info for the resource array. For implicit binding
+  // the HLSLResourceBindingAttr should have been added by SemaHLSL.
+  ResourceBindingAttrs Binding(ArrayDecl);
+  assert(Binding.hasBinding() &&
+         "resource array must have a binding attribute");
+
+  // Find the individual resource type.
+  ASTContext &AST = ArrayDecl->getASTContext();
+  QualType ResTy = AST.getBaseElementType(ResultTy);
+  const auto *ResArrayTy = cast<ConstantArrayType>(ResultTy.getTypePtr());
+
+  // Use the provided LHS for the result.
+  AggValueSlot ValueSlot = AggValueSlot::forAddr(
+      LHS.getAddress(), Qualifiers(), AggValueSlot::IsDestructed_t(true),
+      AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsAliased_t(false),
+      AggValueSlot::DoesNotOverlap);
+
+  // Create Value for index and total array size (= range size).
+  int Size = getTotalArraySize(AST, ResArrayTy);
+  llvm::Value *Zero = llvm::ConstantInt::get(CGM.IntTy, 0);
+  llvm::Value *Range = llvm::ConstantInt::get(CGM.IntTy, Size);
+
+  // Initialize individual resources in the array into LHS.
+  std::optional<llvm::Value *> EndIndex = initializeLocalResourceArray(
+      CGF, ResTy->getAsCXXRecordDecl(), ResArrayTy, ValueSlot, Range, Zero,
+      ArrayDecl->getName(), Binding, {Zero}, RHSExpr->getExprLoc());
+  return EndIndex.has_value();
+}
+
 std::optional<LValue> CGHLSLRuntime::emitBufferArraySubscriptExpr(
     const ArraySubscriptExpr *E, CodeGenFunction &CGF,
     llvm::function_ref<llvm::Value *(bool Promote)> EmitIdxAfterBase) {

clang/lib/CodeGen/CGHLSLRuntime.h

@@ -258,6 +258,7 @@ class CGHLSLRuntime {
   std::optional<LValue>
   emitResourceArraySubscriptExpr(const ArraySubscriptExpr *E,
                                  CodeGenFunction &CGF);
+  bool emitResourceArrayCopy(LValue &LHS, Expr *RHSExpr, CodeGenFunction &CGF);
 
   std::optional<LValue> emitBufferArraySubscriptExpr(
       const ArraySubscriptExpr *E, CodeGenFunction &CGF,

clang/lib/CodeGen/CodeGenModule.cpp

@@ -5976,7 +5976,8 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
              (D->getType()->isHLSLResourceRecord() ||
               D->getType()->isHLSLResourceRecordArray())) {
     Init = llvm::PoisonValue::get(getTypes().ConvertType(ASTTy));
-    NeedsGlobalCtor = D->getType()->isHLSLResourceRecord();
+    NeedsGlobalCtor = D->getType()->isHLSLResourceRecord() ||
+                      D->getStorageClass() == SC_Static;
   } else if (D->hasAttr<LoaderUninitializedAttr>()) {
     Init = llvm::UndefValue::get(getTypes().ConvertTypeForMem(ASTTy));
   } else if (!InitExpr) {

clang/lib/Sema/SemaHLSL.cpp

@@ -4018,7 +4018,9 @@ void SemaHLSL::ActOnVariableDeclarator(VarDecl *VD) {
     // process explicit bindings
     processExplicitBindingsOnDecl(VD);
 
-    if (VD->getType()->isHLSLResourceRecordArray()) {
+    // Add implicit binding attribute to non-static resource arrays.
+    if (VD->getType()->isHLSLResourceRecordArray() &&
+        VD->getStorageClass() != SC_Static) {
       // If the resource array does not have an explicit binding attribute,
       // create an implicit one. It will be used to transfer implicit binding
       // order_ID to codegen.
@@ -4212,8 +4214,8 @@ bool SemaHLSL::ActOnUninitializedVarDecl(VarDecl *VD) {
   if (VD->getType().getAddressSpace() == LangAS::hlsl_constant)
     return true;
 
-  // Initialize resources at the global scope
-  if (VD->hasGlobalStorage()) {
+  // Initialize non-static resources at the global scope.
+  if (VD->hasGlobalStorage() && VD->getStorageClass() != SC_Static) {
     const Type *Ty = VD->getType().getTypePtr();
     if (Ty->isHLSLResourceRecord())
       return initGlobalResourceDecl(VD);
@@ -4237,10 +4239,10 @@ bool SemaHLSL::CheckResourceBinOp(BinaryOperatorKind Opc, Expr *LHSExpr,
   while (auto *ASE = dyn_cast<ArraySubscriptExpr>(E))
     E = ASE->getBase()->IgnoreParenImpCasts();
 
-  // Report error if LHS is a resource declared at a global scope.
+  // Report error if LHS is a non-static resource declared at a global scope.
   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParens())) {
     if (VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
-      if (VD->hasGlobalStorage()) {
+      if (VD->hasGlobalStorage() && VD->getStorageClass() != SC_Static) {
         // assignment to global resource is not allowed
         SemaRef.Diag(Loc, diag::err_hlsl_assign_to_global_resource) << VD;
         SemaRef.Diag(VD->getLocation(), diag::note_var_declared_here) << VD;

clang/test/SemaHLSL/static_resources.hlsl

@@ -0,0 +1,138 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.6-compute -emit-llvm -disable-llvm-passes -o - %s | llvm-cxxfilt | FileCheck %s
+
+// CHECK-DAG: [[ONE_STR:@.*]] = private unnamed_addr constant [4 x i8] c"One\00"
+// CHECK-DAG: [[ARRAY_STR:@.*]] = private unnamed_addr constant [6 x i8] c"Array\00"
+// CHECK-DAG: [[ONEWITHCOUNTER_STR:@.*]] = private unnamed_addr constant [15 x i8] c"OneWithCounter\00"
+// CHECK-DAG: [[ARRAYWITHCOUNTER_STR:@.*]] = private unnamed_addr constant [17 x i8] c"ArrayWithCounter\00"
+// CHECK-NOT: private unnamed_addr constant [{{[0-9]+}} x i8] c"Static
+
+RWBuffer<float> One : register(u1, space5);
+RWBuffer<float> Array[2] : register(u10, space6);
+RWStructuredBuffer<int> OneWithCounter : register(u2, space4);
+RWStructuredBuffer<int> ArrayWithCounter[2] : register(u7, space4);
+
+// Check that the non-static resource One is initialized from binding on
+// startup (register 1, space 5).
+// CHECK: define internal void @__cxx_global_var_init{{.*}}
+// CHECK-NEXT: entry:
+// CHECK-NEXT: call void @hlsl::RWBuffer<float>::__createFromBinding(unsigned int, unsigned int, int, unsigned int, char const*)
+// CHECK-SAME: (ptr {{.*}} @One, i32 noundef 1, i32 noundef 5, i32 noundef 1, i32 noundef 0, ptr noundef [[ONE_STR]])
+
+// Check that the non-static resource OneWithCounter is initialized from binding on
+// startup (register 2, space 4).
+// CHECK: define internal void @__cxx_global_var_init{{.*}}
+// CHECK-NEXT: entry:
+// CHECK-NEXT: call void @hlsl::RWStructuredBuffer<int>::__createFromBindingWithImplicitCounter(unsigned int, unsigned int, int, unsigned int, char const*, unsigned int)
+// CHECK-SAME: (ptr {{.*}} @OneWithCounter, i32 noundef 2, i32 noundef 4, i32 noundef 1, i32 noundef 0, ptr noundef [[ONEWITHCOUNTER_STR]], i32 noundef 0)
+
+// Note that non-static resource arrays are not initialized on startup.
+// The individual resources from the array are initialized on access.
+
+static RWBuffer<float> StaticOne;
+static RWBuffer<float> StaticArray[2];
+
+// Check that StaticOne resource is initialized on startup with the default
+// constructor and not from binding. It will initalize the handle to poison.
+// CHECK: define internal void @__cxx_global_var_init{{.*}}
+// CHECK-NEXT: entry:
+// CHECK-NEXT: call void @hlsl::RWBuffer<float>::RWBuffer()(ptr {{.*}} @StaticOne)
+
+// Check that StaticArray elements are initialized on startup with the default
+// constructor and not from binding. The initializer will loop over the array
+// elements and call the default constructor for each one, setting the handle to poison.
+// CHECK: define internal void @__cxx_global_var_init{{.*}}
+// CHECK-NEXT: entry:
+// CHECK-NEXT: br label %arrayctor.loop
+// CHECK: arrayctor.loop:                                   ; preds = %arrayctor.loop, %entry
+// CHECK-NEXT:   %arrayctor.cur = phi ptr [ @StaticArray, %entry ], [ %arrayctor.next, %arrayctor.loop ]
+// CHECK-NEXT: call void @hlsl::RWBuffer<float>::RWBuffer()(ptr {{.*}} %arrayctor.cur)
+// CHECK-NEXT: %arrayctor.next = getelementptr inbounds %"class.hlsl::RWBuffer", ptr %arrayctor.cur, i32 1
+// CHECK-NEXT: %arrayctor.done = icmp eq ptr %arrayctor.next, getelementptr inbounds (%"class.hlsl::RWBuffer", ptr @StaticArray, i32 2)
+// CHECK-NEXT: br i1 %arrayctor.done, label %arrayctor.cont, label %arrayctor.loop
+// CHECK: arrayctor.cont:                                   ; preds = %arrayctor.loop
+// CHECK-NEXT: ret void
+
+static RWStructuredBuffer<int> StaticOneWithCounter;
+
+// Check that StaticOneWithCounter resource is initialized on startup with the default
+// constructor and not from binding. It will initalize the handle to poison.
+// CHECK: define internal void @__cxx_global_var_init{{.*}}
+// CHECK-NEXT: entry:
+// CHECK-NEXT: call void @hlsl::RWStructuredBuffer<int>::RWStructuredBuffer()(ptr {{.*}} @StaticOneWithCounter)
+
+// No other global initialization routines should be present.
+// CHECK-NOT: define internal void @__cxx_global_var_init{{.*}}
+
+[numthreads(4,1,1)]
+void main() {
+// CHECK: define internal void @main()()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: %[[TMP0:.*]] = alloca %"class.hlsl::RWBuffer"
+
+  static RWBuffer<float> StaticLocal;
+// Check that StaticLocal is initialized by default constructor (handle set to poison)
+// and not from binding.
+// call void @hlsl::RWBuffer<float>::RWBuffer()(ptr {{.*}} @main()::StaticLocal)
+
+  StaticLocal = Array[1];
+// A[2][0] is accessed here, so it should be initialized from binding (register 10, space 6, index 1),
+// and then assigned to StaticLocal using = operator.
+// CHECK: call void @hlsl::RWBuffer<float>::__createFromBinding(unsigned int, unsigned int, int, unsigned int, char const*)
+// CHECK-SAME: (ptr {{.*}} %[[TMP0]], i32 noundef 10, i32 noundef 6, i32 noundef 2, i32 noundef 1, ptr noundef [[ARRAY_STR]])
+// CHECK-NEXT: call {{.*}} ptr @hlsl::RWBuffer<float>::operator=({{.*}})(ptr {{.*}} @main()::StaticLocal, ptr {{.*}} %[[TMP0]])
+
+  StaticOne = One;
+// Operator = call to assign non-static One handle to static StaticOne.
+// CHECK-NEXT: call {{.*}} ptr @hlsl::RWBuffer<float>::operator=({{.*}})(ptr {{.*}} @StaticOne, ptr {{.*}} @One)
+
+  StaticArray = Array;
+// Check that each elements of StaticArray is initialized from binding (register 10, space 6, indices 0 and 1).
+// CHECK: call void @hlsl::RWBuffer<float>::__createFromBinding(unsigned int, unsigned int, int, unsigned int, char const*)
+// CHECK-SAME: (ptr {{.*}} sret(%"class.hlsl::RWBuffer") align 4 @StaticArray, i32 noundef 10, i32 noundef 6, i32 noundef 2, i32 noundef 0, ptr noundef [[ARRAY_STR]])
+// CHECK-NEXT: call void @hlsl::RWBuffer<float>::__createFromBinding(unsigned int, unsigned int, int, unsigned int, char const*)
+// CHECK-SAME: (ptr {{.*}} sret(%"class.hlsl::RWBuffer") align 4 getelementptr ([2 x %"class.hlsl::RWBuffer"], ptr @StaticArray, i32 0, i32 1),
+// CHECK-SAME: i32 noundef 10, i32 noundef 6, i32 noundef 2, i32 noundef 1, ptr noundef [[ARRAY_STR]]
+
+  StaticArray[1] = One;
+// Operator = call to assign non-static One handle to StaticArray element.
+// CHECK-NEXT: call {{.*}} ptr @hlsl::RWBuffer<float>::operator=(hlsl::RWBuffer<float> const&)
+// CHECK-SAME: (ptr {{.*}} getelementptr inbounds ([2 x %"class.hlsl::RWBuffer"], ptr @StaticArray, i32 0, i32 1), ptr {{.*}} @One)
+
+  StaticLocal[0] = 123;
+// CHECK-NEXT: %[[PTR0:.*]] = call {{.*}} ptr @hlsl::RWBuffer<float>::operator[](unsigned int)(ptr {{.*}} @main()::StaticLocal, i32 noundef 0)
+// CHECK-NEXT: store float 1.230000e+02, ptr %[[PTR0]]
+
+  StaticOne[1] = 456;
+// CHECK-NEXT: %[[PTR1:.*]] = call {{.*}} ptr @hlsl::RWBuffer<float>::operator[](unsigned int)(ptr {{.*}}) @StaticOne, i32 noundef 1)
+// CHECK-NEXT: store float 4.560000e+02, ptr %[[PTR1]], align 4
+
+  StaticArray[1][2] = 789;
+// CHECK-NEXT: %[[PTR2:.*]] = call {{.*}} ptr @hlsl::RWBuffer<float>::operator[](unsigned int)
+// CHECK-SAME: (ptr {{.*}} getelementptr inbounds ([2 x %"class.hlsl::RWBuffer"], ptr @StaticArray, i32 0, i32 1), i32 noundef 2)
+// CHECK-NEXT: store float 7.890000e+02, ptr %[[PTR2]], align 4
+
+  static RWStructuredBuffer<int> StaticLocalWithCounter;
+// Check that StaticLocalWithCounter is initialized by default constructor (handle set to poison)
+// and not from binding.
+// call void @hlsl::RWStructuredBuffer<int>::RWStructuredBuffer()(ptr {{.*}} @main()::StaticLocalWithCounter)
+
+  static RWStructuredBuffer<int> StaticLocalArrayWithCounter[2];
+
+  StaticLocalWithCounter = OneWithCounter;
+// Operator = call to assign non-static OneWithCounter handles to StaticLocalWithCounter handles.
+// CHECK: call {{.*}} ptr @hlsl::RWStructuredBuffer<int>::operator=(hlsl::RWStructuredBuffer<int> const&)(ptr {{.*}} @main()::StaticLocalWithCounter, ptr {{.*}} @OneWithCounter)
+
+  StaticLocalArrayWithCounter = ArrayWithCounter;
+// Check that each elements of StaticLocalArrayWithCounter is initialized from binding
+// of ArrayWithCounter (register 7, space 4, indices 0 and 1).
+// CHECK: call void @hlsl::RWStructuredBuffer<int>::__createFromBindingWithImplicitCounter(unsigned int, unsigned int, int, unsigned int, char const*, unsigned int)
+// CHECK-SAME: (ptr {{.*}} sret(%"class.hlsl::RWStructuredBuffer") align 4 @main()::StaticLocalArrayWithCounter,
+// CHECK-SAME: i32 noundef 7, i32 noundef 4, i32 noundef 2, i32 noundef 0, ptr noundef [[ARRAYWITHCOUNTER_STR]], i32 noundef 1)
+
+// CHECK-NEXT: call void @hlsl::RWStructuredBuffer<int>::__createFromBindingWithImplicitCounter(unsigned int, unsigned int, int, unsigned int, char const*, unsigned int)
+// CHECK-SAME: (ptr {{.*}} sret(%"class.hlsl::RWStructuredBuffer") align 4 getelementptr ([2 x %"class.hlsl::RWStructuredBuffer"], ptr @main()::StaticLocalArrayWithCounter, i32 0, i32 1),
+// CHECK-SAME: i32 noundef 7, i32 noundef 4, i32 noundef 2, i32 noundef 1, ptr noundef [[ARRAYWITHCOUNTER_STR]], i32 noundef 1)
+}
+
+// No other binding initialization calls should be present.
+// CHECK-NOT: call void @hlsl::RWBuffer<float>::__createFrom{{.*}}Binding{{.*}}