writer[spirv,hlsl]: Call UnwrapRef() for splats

The TypeConstructorExpression logic that tested for splats was not considering references. This led to broken emission for the SPIR-V and HLSL backends.

Fixed: tint:992
Change-Id: I9824b71f526997f91d380c09b459f4fd73065b19
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/58397
Auto-Submit: Ben Clayton <bclayton@google.com>
Commit-Queue: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>

test/bug/tint/992.wgsl

@@ -0,0 +1,6 @@
+[[stage(fragment)]]
+fn frag_main() -> [[location(0)]] vec4<f32> {
+    var b: f32 = 0.0;
+    var v: vec3<f32> = vec3<f32>(b);
+    return vec4<f32>(v, 1.0);
+}

test/bug/tint/992.wgsl.expected.hlsl

@@ -0,0 +1,10 @@
+struct tint_symbol {
+  float4 value : SV_Target0;
+};
+
+tint_symbol frag_main() {
+  float b = 0.0f;
+  float3 v = float3((b).xxx);
+  const tint_symbol tint_symbol_1 = {float4(v, 1.0f)};
+  return tint_symbol_1;
+}

test/bug/tint/992.wgsl.expected.msl

@@ -0,0 +1,14 @@
+#include <metal_stdlib>
+
+using namespace metal;
+struct tint_symbol {
+  float4 value [[color(0)]];
+};
+
+fragment tint_symbol frag_main() {
+  float b = 0.0f;
+  float3 v = float3(b);
+  tint_symbol const tint_symbol_1 = {.value=float4(v, 1.0f)};
+  return tint_symbol_1;
+}
+

test/bug/tint/992.wgsl.expected.spvasm

@@ -0,0 +1,53 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 31
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Fragment %frag_main "frag_main" %tint_symbol_1
+               OpExecutionMode %frag_main OriginUpperLeft
+               OpName %tint_symbol_1 "tint_symbol_1"
+               OpName %tint_symbol_2 "tint_symbol_2"
+               OpName %tint_symbol "tint_symbol"
+               OpName %frag_main "frag_main"
+               OpName %b "b"
+               OpName %v "v"
+               OpDecorate %tint_symbol_1 Location 0
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+%tint_symbol_1 = OpVariable %_ptr_Output_v4float Output %5
+       %void = OpTypeVoid
+          %6 = OpTypeFunction %void %v4float
+         %11 = OpTypeFunction %void
+    %float_0 = OpConstant %float 0
+%_ptr_Function_float = OpTypePointer Function %float
+         %17 = OpConstantNull %float
+    %v3float = OpTypeVector %float 3
+%_ptr_Function_v3float = OpTypePointer Function %v3float
+         %23 = OpConstantNull %v3float
+    %float_1 = OpConstant %float 1
+%tint_symbol_2 = OpFunction %void None %6
+%tint_symbol = OpFunctionParameter %v4float
+         %10 = OpLabel
+               OpStore %tint_symbol_1 %tint_symbol
+               OpReturn
+               OpFunctionEnd
+  %frag_main = OpFunction %void None %11
+         %13 = OpLabel
+          %b = OpVariable %_ptr_Function_float Function %17
+          %v = OpVariable %_ptr_Function_v3float Function %23
+               OpStore %b %float_0
+         %19 = OpLoad %float %b
+         %20 = OpCompositeConstruct %v3float %19 %19 %19
+               OpStore %v %20
+         %25 = OpLoad %v3float %v
+         %26 = OpCompositeExtract %float %25 0
+         %27 = OpCompositeExtract %float %25 1
+         %28 = OpCompositeExtract %float %25 2
+         %30 = OpCompositeConstruct %v4float %26 %27 %28 %float_1
+         %24 = OpFunctionCall %void %tint_symbol_2 %30
+               OpReturn
+               OpFunctionEnd

test/bug/tint/992.wgsl.expected.wgsl

@@ -0,0 +1,6 @@
+[[stage(fragment)]]
+fn frag_main() -> [[location(0)]] vec4<f32> {
+  var b : f32 = 0.0;
+  var v : vec3<f32> = vec3<f32>(b);
+  return vec4<f32>(v, 1.0);
+}