[HLSL] Reland; Make it possible to assign an array from a cbuffer (#136580)

Reland #134174 
Update Sema Checking to always do an HLSL Array RValue cast in the case
we are dealing with hlsl constant array types
Instead of comparing canonical types, compare canonical unqualified
types
Add a test to show it is possible to assign an array from a cbuffer.
Closes #133767

Author: spall

clang/lib/Sema/SemaExprCXX.cpp

@@ -4745,19 +4745,13 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
   case ICK_HLSL_Array_RValue:
     if (ToType->isArrayParameterType()) {
       FromType = Context.getArrayParameterType(FromType);
-      From = ImpCastExprToType(From, FromType, CK_HLSLArrayRValue, VK_PRValue,
-                               /*BasePath=*/nullptr, CCK)
-                 .get();
-    } else { // FromType must be ArrayParameterType
-      assert(FromType->isArrayParameterType() &&
-             "FromType must be ArrayParameterType in ICK_HLSL_Array_RValue \
-              if it is not ToType");
+    } else if (FromType->isArrayParameterType()) {
       const ArrayParameterType *APT = cast<ArrayParameterType>(FromType);
       FromType = APT->getConstantArrayType(Context);
-      From = ImpCastExprToType(From, FromType, CK_HLSLArrayRValue, VK_PRValue,
-                               /*BasePath=*/nullptr, CCK)
-                 .get();
     }
+    From = ImpCastExprToType(From, FromType, CK_HLSLArrayRValue, VK_PRValue,
+                             /*BasePath=*/nullptr, CCK)
+               .get();
     break;
 
   case ICK_Function_To_Pointer:

clang/lib/Sema/SemaOverload.cpp

@@ -2275,17 +2275,16 @@ static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
     // handling here.
     if (ToType->isArrayParameterType()) {
       FromType = S.Context.getArrayParameterType(FromType);
-      SCS.First = ICK_HLSL_Array_RValue;
     } else if (FromType->isArrayParameterType()) {
       const ArrayParameterType *APT = cast<ArrayParameterType>(FromType);
       FromType = APT->getConstantArrayType(S.Context);
-      SCS.First = ICK_HLSL_Array_RValue;
-    } else {
-      SCS.First = ICK_Identity;
     }
 
-    if (S.Context.getCanonicalType(FromType) !=
-        S.Context.getCanonicalType(ToType))
+    SCS.First = ICK_HLSL_Array_RValue;
+
+    // Don't consider qualifiers, which include things like address spaces
+    if (FromType.getCanonicalType().getUnqualifiedType() !=
+        ToType.getCanonicalType().getUnqualifiedType())
       return false;
 
     SCS.setAllToTypes(ToType);

clang/test/CodeGenHLSL/ArrayAssignable.hlsl

@@ -1,4 +1,23 @@
-// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s --enable-var-scope
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -finclude-default-header -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s
+
+struct S {
+  int x;
+  float f;
+};
+
+// CHECK: [[CBLayout:%.*]] = type <{ [2 x float], [2 x <4 x i32>], [2 x [2 x i32]], [1 x target("dx.Layout", %S, 8, 0, 4)] }>
+// CHECK: @CBArrays.cb = global target("dx.CBuffer", target("dx.Layout", [[CBLayout]], 136, 0, 32, 64, 128))
+// CHECK: @c1 = external addrspace(2) global [2 x float], align 4
+// CHECK: @c2 = external addrspace(2) global [2 x <4 x i32>], align 16
+// CHECK: @c3 = external addrspace(2) global [2 x [2 x i32]], align 4
+// CHECK: @c4 = external addrspace(2) global [1 x target("dx.Layout", %S, 8, 0, 4)], align 4
+
+cbuffer CBArrays : register(b0) {
+  float c1[2];
+  int4 c2[2];
+  int c3[2][2];
+  S c4[1];
+}
 
 // CHECK-LABEL: define void {{.*}}arr_assign1
 // CHECK: [[Arr:%.*]] = alloca [2 x i32], align 4
@@ -116,3 +135,45 @@ void arr_assign7() {
   int Arr2[2][2] = {{0, 0}, {1, 1}};
   (Arr = Arr2)[0] = {6, 6};
 }
+
+// Verify you can assign from a cbuffer array
+
+// CHECK-LABEL: define void {{.*}}arr_assign8
+// CHECK: [[C:%.*]] = alloca [2 x float], align 4
+// CHECK-NEXT: call void @llvm.memcpy.p0.p0.i32(ptr align 4 [[C]], ptr align 4 {{.*}}, i32 8, i1 false)
+// CHECK-NEXT: call void @llvm.memcpy.p0.p2.i32(ptr align 4 [[C]], ptr addrspace(2) align 4 @c1, i32 8, i1 false)
+// CHECK-NEXT: ret void
+void arr_assign8() {
+  float C[2] = {1.0, 2.0};
+  C = c1;
+}
+
+// CHECK-LABEL: define void {{.*}}arr_assign9
+// CHECK: [[C:%.*]] = alloca [2 x <4 x i32>], align 16
+// CHECK-NEXT: call void @llvm.memcpy.p0.p0.i32(ptr align 16 [[C]], ptr align 16 {{.*}}, i32 32, i1 false)
+// CHECK-NEXT: call void @llvm.memcpy.p0.p2.i32(ptr align 16 [[C]], ptr addrspace(2) align 16 @c2, i32 32, i1 false)
+// CHECK-NEXT: ret void
+void arr_assign9() {
+  int4 C[2] = {1,2,3,4,5,6,7,8};
+  C = c2;
+}
+
+// CHECK-LABEL: define void {{.*}}arr_assign10
+// CHECK: [[C:%.*]] = alloca [2 x [2 x i32]], align 4
+// CHECK-NEXT: call void @llvm.memcpy.p0.p0.i32(ptr align 4 [[C]], ptr align 4 {{.*}}, i32 16, i1 false)
+// CHECK-NEXT: call void @llvm.memcpy.p0.p2.i32(ptr align 4 [[C]], ptr addrspace(2) align 4 @c3, i32 16, i1 false)
+// CHECK-NEXT: ret void
+void arr_assign10() {
+  int C[2][2] = {1,2,3,4};
+  C = c3;
+}
+
+// CHECK-LABEL: define void {{.*}}arr_assign11
+// CHECK: [[C:%.*]] = alloca [1 x %struct.S], align 4
+// CHECK: call void @llvm.memcpy.p0.p2.i32(ptr align 4 [[C]], ptr addrspace(2) align 4 @c4, i32 8, i1 false)
+// CHECK-NEXT: ret void
+void arr_assign11() {
+  S s = {1, 2.0};
+  S C[1] = {s};
+  C = c4;
+}