[HLSL] fix D3DCOLORtoUBYTE4 return type to be int (#151353)

fixes #150673
fixes #150678

The issue was we were using the wrong return type.

Author: farzonl

clang/lib/Headers/hlsl/hlsl_intrinsic_helpers.h

@@ -12,7 +12,7 @@
 namespace hlsl {
 namespace __detail {
 
-constexpr vector<uint, 4> d3d_color_to_ubyte4_impl(vector<float, 4> V) {
+constexpr int4 d3d_color_to_ubyte4_impl(float4 V) {
   // Use the same scaling factor used by FXC, and DXC for DXIL
   // (i.e., 255.001953)
   // https://github.com/microsoft/DirectXShaderCompiler/blob/070d0d5a2beacef9eeb51037a9b04665716fd6f3/lib/HLSL/HLOperationLower.cpp#L666C1-L697C2

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -418,7 +418,7 @@ const inline float4 lit(float NDotL, float NDotH, float M) {
 /// This function swizzles and scales components of the \a x parameter. Use this
 /// function to compensate for the lack of UBYTE4 support in some hardware.
 
-constexpr vector<uint, 4> D3DCOLORtoUBYTE4(vector<float, 4> V) {
+constexpr int4 D3DCOLORtoUBYTE4(float4 V) {
   return __detail::d3d_color_to_ubyte4_impl(V);
 }
 

clang/test/CodeGenHLSL/builtins/D3DCOLORtoUBYTE4.hlsl

@@ -5,8 +5,16 @@
 // CHECK-LABEL: D3DCOLORtoUBYTE4
 int4 test_D3DCOLORtoUBYTE4(float4 p1) {
   // CHECK: %[[SCALED:.*]] = fmul [[FMFLAGS:.*]][[FLOAT_TYPE:<4 x float>]] %{{.*}}, splat (float 0x406FE01000000000)
-  // CHECK: %[[CONVERTED:.*]] = fptoui [[FLOAT_TYPE]] %[[SCALED]] to [[INT_TYPE:<4 x i32>]]
+  // CHECK: %[[CONVERTED:.*]] = fptosi [[FLOAT_TYPE]] %[[SCALED]] to [[INT_TYPE:<4 x i32>]]
   // CHECK: %[[SHUFFLED:.*]] = shufflevector [[INT_TYPE]] %[[CONVERTED]], [[INT_TYPE]] poison, <4 x i32> <i32 2, i32 1, i32 0, i32 3>
   // CHECK: ret [[INT_TYPE]] %[[SHUFFLED]]
   return D3DCOLORtoUBYTE4(p1);
 }
+
+// Note this test confirms issue 150673 is fixed 
+// by confirming the negative does not become a poison
+// CHECK-LABEL: test_constant_inputs
+int4 test_constant_inputs() {
+  // CHECK: ret <4 x i32> <i32 -12877, i32 2833, i32 0, i32 25500>
+  return D3DCOLORtoUBYTE4(float4(0, 11.11, -50.5, 100));
+}

clang/test/SemaHLSL/BuiltIns/D3DCOLORtoUBYTE4-errors.hlsl

@@ -25,5 +25,5 @@ struct S {
 int4 struct_arg(S v) {
     return D3DCOLORtoUBYTE4(v);
     // expected-error@-1 {{no matching function for call to 'D3DCOLORtoUBYTE4'}}
-    // expected-note@hlsl/hlsl_intrinsics.h:* {{candidate function not viable: no known conversion from 'S' to 'vector<float, 4>' (vector of 4 'float' values) for 1st argument}}
+    // expected-note@hlsl/hlsl_intrinsics.h:* {{candidate function not viable: no known conversion from 'S' to 'float4' (aka 'vector<float, 4>') for 1st argument}}
 }