HLSL: Fix #1064: Don't include empty structures on OpEntryPoint

SPIRV/GlslangToSpv.cpp

@@ -1081,8 +1081,10 @@ void TGlslangToSpvTraverser::visitSymbol(glslang::TIntermSymbol* symbol)
     // Include all "static use" and "linkage only" interface variables on the OpEntryPoint instruction
     if (builder.isPointer(id)) {
         spv::StorageClass sc = builder.getStorageClass(id);
-        if (sc == spv::StorageClassInput || sc == spv::StorageClassOutput)
-            iOSet.insert(id);
+        if (sc == spv::StorageClassInput || sc == spv::StorageClassOutput) {
+            if (!symbol->getType().isStruct() || symbol->getType().getStruct()->size() > 0)
+                iOSet.insert(id);
+        }
     }
 
     // Only process non-linkage-only nodes for generating actual static uses

Test/baseResults/hlsl.emptystructreturn.frag.out

@@ -56,7 +56,7 @@ gl_FragCoord origin is upper left
                               Capability Shader
                1:             ExtInstImport  "GLSL.std.450"
                               MemoryModel Logical GLSL450
-                              EntryPoint Fragment 4  "main" 20 23
+                              EntryPoint Fragment 4  "main"
                               ExecutionMode 4 OriginUpperLeft
                               Source HLSL 500
                               Name 4  "main"

Test/baseResults/hlsl.emptystructreturn.vert.out

@@ -54,7 +54,7 @@ Shader version: 500
                               Capability Shader
                1:             ExtInstImport  "GLSL.std.450"
                               MemoryModel Logical GLSL450
-                              EntryPoint Vertex 4  "main" 20 23
+                              EntryPoint Vertex 4  "main"
                               Source HLSL 500
                               Name 4  "main"
                               Name 6  "vs_in"