Fix non statically used fragment input structs on HLSL

src/compiler/translator/VariableInfo.cpp

@@ -66,6 +66,24 @@ VarT *FindVariable(const TString &name, std::vector<VarT> *infoList)
     return nullptr;
 }
 
+// Note that this shouldn't be called for interface blocks - static use information is collected for
+// individual fields in case of interface blocks.
+void MarkStaticallyUsed(ShaderVariable *variable)
+{
+    if (!variable->staticUse)
+    {
+        if (variable->isStruct())
+        {
+            // Conservatively assume all fields are statically used as well.
+            for (auto &field : variable->fields)
+            {
+                MarkStaticallyUsed(&field);
+            }
+        }
+        variable->staticUse = true;
+    }
+}
+
 // Traverses the intermediate tree to collect all attributes, uniforms, varyings, fragment outputs,
 // and interface blocks.
 class CollectVariablesTraverser : public TIntermTraverser
@@ -406,7 +424,7 @@ void CollectVariablesTraverser::visitSymbol(TIntermSymbol *symbol)
     }
     if (var)
     {
-        var->staticUse = true;
+        MarkStaticallyUsed(var);
     }
 }
 

src/libANGLE/Program.cpp

@@ -2388,7 +2388,8 @@ std::vector<PackedVarying> Program::getPackedVaryings(
             // Will get the vertex shader interpolation by default.
             auto interpolation = ref.second.get()->interpolation;
 
-            // Interpolation qualifiers must match.
+            // Note that we lose the vertex shader static use information here. The data for the
+            // variable is taken from the fragment shader.
             if (output->isStruct())
             {
                 ASSERT(!output->isArray());

src/libANGLE/renderer/d3d/DynamicHLSL.cpp

@@ -741,10 +741,9 @@ void DynamicHLSL::generateShaderLinkHLSL(const gl::Context *context,
         const auto &varying = *packedVarying.varying;
         ASSERT(!varying.isBuiltIn() && !varying.isStruct());
 
-        // Don't reference VS-only transform feedback varyings in the PS.
-        // TODO: Consider updating the fragment shader's varyings with a parameter signaling that a
-        // varying is only used in the vertex shader in MergeVaryings
-        if (packedVarying.vertexOnly || (!varying.staticUse && !packedVarying.isStructField()))
+        // Don't reference VS-only transform feedback varyings in the PS. Note that we're relying on
+        // that the staticUse flag is set according to usage in the fragment shader.
+        if (packedVarying.vertexOnly || !varying.staticUse)
             continue;
 
         pixelStream << "    ";

src/tests/gl_tests/GLSLTest.cpp

@@ -3157,6 +3157,100 @@ TEST_P(GLSLTest, StructsWithSameMembersDisambiguatedByName)
     EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
 }
 
+// Test that a varying struct that's not statically used in the fragment shader works.
+// GLSL ES 3.00.6 section 4.3.10.
+TEST_P(GLSLTest_ES3, VaryingStructNotStaticallyUsedInFragmentShader)
+{
+    const std::string &vertexShader =
+        "#version 300 es\n"
+        "struct S {\n"
+        "    vec4 field;\n"
+        "};\n"
+        "out S varStruct;\n"
+        "void main()\n"
+        "{\n"
+        "    gl_Position = vec4(1.0);\n"
+        "    varStruct.field = vec4(0.0, 0.5, 0.0, 0.0);\n"
+        "}\n";
+
+    const std::string &fragmentShader =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "struct S {\n"
+        "    vec4 field;\n"
+        "};\n"
+        "in S varStruct;\n"
+        "out vec4 col;\n"
+        "void main()\n"
+        "{\n"
+        "    col = vec4(1.0);\n"
+        "}\n";
+
+    ANGLE_GL_PROGRAM(program, vertexShader, fragmentShader);
+}
+
+// Test that a varying struct that's not declared in the fragment shader links successfully.
+// GLSL ES 3.00.6 section 4.3.10.
+TEST_P(GLSLTest_ES3, VaryingStructNotDeclaredInFragmentShader)
+{
+    const std::string &vertexShader =
+        "#version 300 es\n"
+        "struct S {\n"
+        "    vec4 field;\n"
+        "};\n"
+        "out S varStruct;\n"
+        "void main()\n"
+        "{\n"
+        "    gl_Position = vec4(1.0);\n"
+        "    varStruct.field = vec4(0.0, 0.5, 0.0, 0.0);\n"
+        "}\n";
+
+    const std::string &fragmentShader =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "out vec4 col;\n"
+        "void main()\n"
+        "{\n"
+        "    col = vec4(1.0);\n"
+        "}\n";
+
+    ANGLE_GL_PROGRAM(program, vertexShader, fragmentShader);
+}
+
+// Test that a varying struct that gets used in the fragment shader works.
+TEST_P(GLSLTest_ES3, VaryingStructUsedInFragmentShader)
+{
+    const std::string &vertexShader =
+        "#version 300 es\n"
+        "in vec4 inputAttribute;\n"
+        "struct S {\n"
+        "    vec4 field;\n"
+        "};\n"
+        "out S varStruct;\n"
+        "void main()\n"
+        "{\n"
+        "    gl_Position = inputAttribute;\n"
+        "    varStruct.field = vec4(0.0, 1.0, 0.0, 1.0);\n"
+        "}\n";
+
+    const std::string &fragmentShader =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "out vec4 col;\n"
+        "struct S {\n"
+        "    vec4 field;\n"
+        "};\n"
+        "in S varStruct;\n"
+        "void main()\n"
+        "{\n"
+        "    col = varStruct.field;\n"
+        "}\n";
+
+    ANGLE_GL_PROGRAM(program, vertexShader, fragmentShader);
+    drawQuad(program.get(), "inputAttribute", 0.5f);
+    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
+}
+
 // Use this to select which configurations (e.g. which renderer, which GLES major version) these tests should be run against.
 ANGLE_INSTANTIATE_TEST(GLSLTest,
                        ES2_D3D9(),