HLSL: Tests: Add subset of flattened opaque test to legalize results.

Test/baseLegalResults/hlsl.flattenSubset.frag.out

+hlsl.flattenSubset.frag
+WARNING: AST will form illegal SPIR-V; need to transform to legalize
+// Module Version 10000
+// Generated by (magic number): 80001
+// Id's are bound by 85
+
+                              Capability Shader
+               1:             ExtInstImport  "GLSL.std.450"
+                              MemoryModel Logical GLSL450
+                              EntryPoint Fragment 4  "main" 54 57
+                              ExecutionMode 4 OriginUpperLeft
+                              Source HLSL 500
+                              Name 4  "main"
+                              Name 17  "samp"
+                              Name 41  "tex"
+                              Name 54  "vpos"
+                              Name 57  "@entryPointOutput"
+                              Decorate 17(samp) DescriptorSet 0
+                              Decorate 41(tex) DescriptorSet 0
+                              Decorate 54(vpos) Location 0
+                              Decorate 57(@entryPointOutput) Location 0
+               2:             TypeVoid
+               3:             TypeFunction 2
+               6:             TypeFloat 32
+               7:             TypeVector 6(float) 4
+              13:             TypeSampler
+              16:             TypePointer UniformConstant 13
+        17(samp):     16(ptr) Variable UniformConstant
+              39:             TypeImage 6(float) 2D sampled format:Unknown
+              40:             TypePointer UniformConstant 39
+         41(tex):     40(ptr) Variable UniformConstant
+              44:             TypeSampledImage 39
+              46:             TypeVector 6(float) 2
+              47:    6(float) Constant 1056964608
+              48:   46(fvec2) ConstantComposite 47 47
+              53:             TypePointer Input 7(fvec4)
+        54(vpos):     53(ptr) Variable Input
+              56:             TypePointer Output 7(fvec4)
+57(@entryPointOutput):     56(ptr) Variable Output
+         4(main):           2 Function None 3
+               5:             Label
+              74:          13 Load 17(samp)
+              81:          39 Load 41(tex)
+              83:          44 SampledImage 81 74
+              84:    7(fvec4) ImageSampleImplicitLod 83 48
+                              Store 57(@entryPointOutput) 84
+                              Return
+                              FunctionEnd

Test/hlsl.flattenSubset.frag

@@ -23,10 +23,14 @@ struct S2
     S1 resources;
 };
 
+SamplerState samp;
+Texture2D tex;
+
 float4 main(float4 vpos : VPOS) : COLOR0
 {
     S1 s1;
     S2 s2;
+    s1.s0.ss = samp;
     s2.resources = s1;
-    return float4(0,0,0,0);
+    return tex.Sample(s2.resources.s0.ss, float2(0.5));
 }

gtests/Hlsl.FromFile.cpp

@@ -379,7 +379,8 @@ INSTANTIATE_TEST_CASE_P(
         {"hlsl.aliasOpaque.frag", "main"},
         {"hlsl.flattenOpaque.frag", "main"},
         {"hlsl.flattenOpaqueInit.vert", "main"},
-        {"hlsl.flattenOpaqueInitMix.vert", "main"}
+        {"hlsl.flattenOpaqueInitMix.vert", "main"},
+        {"hlsl.flattenSubset.frag", "main"}
     }),
     FileNameAsCustomTestSuffix
 );