Fix bug - initialize resource arrays to poison, add test

Author: hekota

clang/lib/CodeGen/CodeGenModule.cpp

@@ -5752,11 +5752,16 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
       (D->getType()->isCUDADeviceBuiltinSurfaceType() ||
        D->getType()->isCUDADeviceBuiltinTextureType());
   if (getLangOpts().CUDA &&
-      (IsCUDASharedVar || IsCUDAShadowVar || IsCUDADeviceShadowVar))
+      (IsCUDASharedVar || IsCUDAShadowVar || IsCUDADeviceShadowVar)) {
     Init = llvm::UndefValue::get(getTypes().ConvertTypeForMem(ASTTy));
-  else if (D->hasAttr<LoaderUninitializedAttr>())
+  } else if (getLangOpts().HLSL &&
+             (D->getType()->isHLSLResourceRecord() ||
+              D->getType()->isHLSLResourceRecordArray())) {
+    Init = llvm::PoisonValue::get(getTypes().ConvertType(ASTTy));
+    NeedsGlobalCtor = D->getType()->isHLSLResourceRecord();
+  } else if (D->hasAttr<LoaderUninitializedAttr>()) {
     Init = llvm::UndefValue::get(getTypes().ConvertTypeForMem(ASTTy));
-  else if (!InitExpr) {
+  } else if (!InitExpr) {
     // This is a tentative definition; tentative definitions are
     // implicitly initialized with { 0 }.
     //
@@ -5777,11 +5782,7 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
       if (D->getType()->isReferenceType())
         T = D->getType();
 
-      if (getLangOpts().HLSL && (D->getType()->isHLSLResourceRecord() ||
-                                 D->getType()->isHLSLResourceRecordArray())) {
-        Init = llvm::PoisonValue::get(getTypes().ConvertType(ASTTy));
-        NeedsGlobalCtor = true;
-      } else if (getLangOpts().CPlusPlus) {
+      if (getLangOpts().CPlusPlus) {
         Init = EmitNullConstant(T);
         if (!IsDefinitionAvailableExternally)
           NeedsGlobalCtor = true;

clang/test/CodeGenHLSL/resources/resource-bindings.hlsl

@@ -4,11 +4,13 @@
 // CHECK: %"class.hlsl::RWBuffer.0" = type { target("dx.TypedBuffer", float, 1, 0, 0) }
 // CHECK: %"class.hlsl::StructuredBuffer" = type { target("dx.RawBuffer", i32, 0, 0) }
 // CHECK: %"class.hlsl::RWStructuredBuffer" = type { target("dx.RawBuffer", %struct.S, 1, 0) }
+// CHECK: %"class.hlsl::RWBuffer.1" = type { target("dx.TypedBuffer", double, 1, 0, 0) }
 
 // CHECK: @_ZL4U0S0 = internal global %"class.hlsl::RWBuffer" poison, align 4
 // CHECK: @_ZL4U5S3 = internal global %"class.hlsl::RWBuffer.0" poison, align 4
 // CHECK: @_ZL4T2S2 = internal global %"class.hlsl::StructuredBuffer" poison, align 4
 // CHECK: @_ZL4T3S0 = internal global %"class.hlsl::RWStructuredBuffer" poison, align 4
+// CHECK: @_ZL5Array = internal global [10 x %"class.hlsl::RWBuffer.1"] poison, align 4
 
 // CHECK: %[[HANDLE:.*]] = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0)
 // CHECK-SAME: @llvm.dx.resource.handlefrombinding.tdx.TypedBuffer_v4f32_1_0_0t(
@@ -42,5 +44,15 @@ struct S {
 };
 RWStructuredBuffer<S> T3S0 : register(u3);
 
+// Resource array elements are initialized on access; make sure there is not call
+// to initialize RWBuffer<double>.
+// CHECK-NOT: call target("dx.TypedBuffer", double, 1, 0, 0) @llvm.dx.resource.handlefrombinding.tdx.TypedBuffer_f64_1_0_0t(
+RWBuffer<double> Array[10] : register(u4, space0);
+
 [numthreads(4,1,1)]
-void main() {}
+void main() {
+  // Reference Array to ensure it is emitted and we can test that it is initialized
+  // to poison, but do not index it.
+  // Non-array resources are always emitted because they have a constructor initializer.
+  (void)Array;
+}