Vulkan: Add support for EXT_blend_func_extended

src/compiler/translator/TranslatorVulkan.cpp

@@ -1005,10 +1005,12 @@ bool TranslatorVulkan::translateImpl(TIntermBlock *root,
                 }
             }
 
-            bool hasGLFragColor  = false;
-            bool hasGLFragData   = false;
-            bool usePreRotation  = (compileOptions & SH_ADD_PRE_ROTATION) != 0;
-            bool hasGLSampleMask = false;
+            bool hasGLFragColor          = false;
+            bool hasGLFragData           = false;
+            bool usePreRotation          = (compileOptions & SH_ADD_PRE_ROTATION) != 0;
+            bool hasGLSampleMask         = false;
+            bool hasGLSecondaryFragColor = false;
+            bool hasGLSecondaryFragData  = false;
 
             for (const ShaderVariable &outputVar : mOutputVariables)
             {
@@ -1030,11 +1032,24 @@ bool TranslatorVulkan::translateImpl(TIntermBlock *root,
                     hasGLSampleMask = true;
                     continue;
                 }
+                else if (outputVar.name == "gl_SecondaryFragColorEXT")
+                {
+                    ASSERT(!hasGLSecondaryFragColor);
+                    hasGLSecondaryFragColor = true;
+                    continue;
+                }
+                else if (outputVar.name == "gl_SecondaryFragDataEXT")
+                {
+                    ASSERT(!hasGLSecondaryFragData);
+                    hasGLSecondaryFragData = true;
+                    continue;
+                }
             }
 
             // Declare gl_FragColor and glFragData as webgl_FragColor and webgl_FragData
             // if it's core profile shaders and they are used.
-            ASSERT(!(hasGLFragColor && hasGLFragData));
+            ASSERT(!((hasGLFragColor || hasGLSecondaryFragColor) &&
+                     (hasGLFragData || hasGLSecondaryFragData)));
             if (hasGLFragColor)
             {
                 sink << "layout(location = 0) out vec4 webgl_FragColor;\n";
@@ -1043,6 +1058,15 @@ bool TranslatorVulkan::translateImpl(TIntermBlock *root,
             {
                 sink << "layout(location = 0) out vec4 webgl_FragData[gl_MaxDrawBuffers];\n";
             }
+            if (hasGLSecondaryFragColor)
+            {
+                sink << "layout(location = 0, index = 1) out vec4 angle_SecondaryFragColor;\n";
+            }
+            if (hasGLSecondaryFragData)
+            {
+                sink << "layout(location = 0, index = 1) out vec4 angle_SecondaryFragData["
+                     << getResources().MaxDualSourceDrawBuffers << "];\n";
+            }
 
             if (usesPointCoord)
             {

src/libANGLE/Program.h

@@ -108,6 +108,12 @@ void LoadBlockMemberInfo(BinaryInputStream *stream, sh::BlockMemberInfo *var);
 void WriteShaderVar(BinaryOutputStream *stream, const sh::ShaderVariable &var);
 void LoadShaderVar(BinaryInputStream *stream, sh::ShaderVariable *var);
 
+void WriteInterfaceBlock(BinaryOutputStream *stream, const InterfaceBlock &block);
+void LoadInterfaceBlock(BinaryInputStream *stream, InterfaceBlock *block);
+
+void WriteShaderVariableBuffer(BinaryOutputStream *stream, const ShaderVariableBuffer &var);
+void LoadShaderVariableBuffer(BinaryInputStream *stream, ShaderVariableBuffer *var);
+
 // Struct used for correlating uniforms/elements of uniform arrays to handles
 struct VariableLocation
 {
@@ -233,7 +239,7 @@ class ProgramState final : angle::NonCopyable
     }
     const UniformBlockBindingMask &getActiveUniformBlockBindingsMask() const
     {
-        return mActiveUniformBlockBindings;
+        return mExecutable->getActiveUniformBlockBindings();
     }
     const std::vector<sh::ShaderVariable> &getProgramInputs() const
     {
@@ -250,7 +256,7 @@ class ProgramState final : angle::NonCopyable
     }
     const std::vector<VariableLocation> &getSecondaryOutputLocations() const
     {
-        return mSecondaryOutputLocations;
+        return mExecutable->getSecondaryOutputLocations();
     }
     const std::vector<LinkedUniform> &getUniforms() const { return mExecutable->getUniforms(); }
     const std::vector<VariableLocation> &getUniformLocations() const { return mUniformLocations; }
@@ -386,16 +392,10 @@ class ProgramState final : angle::NonCopyable
     uint32_t mLocationsUsedForXfbExtension;
     std::vector<std::string> mTransformFeedbackVaryingNames;
 
-    // For faster iteration on the blocks currently being bound.
-    UniformBlockBindingMask mActiveUniformBlockBindings;
-
     std::vector<VariableLocation> mUniformLocations;
     std::vector<BufferVariable> mBufferVariables;
     RangeUI mAtomicCounterUniformRange;
 
-    // EXT_blend_func_extended secondary outputs (ones with index 1) in ESSL 3.00 shaders.
-    std::vector<VariableLocation> mSecondaryOutputLocations;
-
     DrawBufferMask mActiveOutputVariables;
 
     // Fragment output variable base types: FLOAT, INT, or UINT.  Ordered by location.

src/libANGLE/ProgramExecutable.h

@@ -233,8 +233,16 @@ class ProgramExecutable final : public angle::Subject
     const std::vector<sh::ShaderVariable> &getProgramInputs() const { return mProgramInputs; }
     const std::vector<sh::ShaderVariable> &getOutputVariables() const { return mOutputVariables; }
     const std::vector<VariableLocation> &getOutputLocations() const { return mOutputLocations; }
+    const std::vector<VariableLocation> &getSecondaryOutputLocations() const
+    {
+        return mSecondaryOutputLocations;
+    }
     const std::vector<LinkedUniform> &getUniforms() const { return mUniforms; }
     const std::vector<InterfaceBlock> &getUniformBlocks() const { return mUniformBlocks; }
+    const UniformBlockBindingMask &getActiveUniformBlockBindings() const
+    {
+        return mActiveUniformBlockBindings;
+    }
     const std::vector<SamplerBinding> &getSamplerBindings() const { return mSamplerBindings; }
     const std::vector<ImageBinding> &getImageBindings() const
     {
@@ -392,6 +400,8 @@ class ProgramExecutable final : public angle::Subject
     // to uniforms.
     std::vector<sh::ShaderVariable> mOutputVariables;
     std::vector<VariableLocation> mOutputLocations;
+    // EXT_blend_func_extended secondary outputs (ones with index 1)
+    std::vector<VariableLocation> mSecondaryOutputLocations;
     bool mYUVOutput;
     // Vertex attributes, Fragment input varyings, etc.
     std::vector<sh::ShaderVariable> mProgramInputs;
@@ -414,6 +424,10 @@ class ProgramExecutable final : public angle::Subject
     RangeUI mDefaultUniformRange;
     RangeUI mSamplerUniformRange;
     std::vector<InterfaceBlock> mUniformBlocks;
+
+    // For faster iteration on the blocks currently being bound.
+    UniformBlockBindingMask mActiveUniformBlockBindings;
+
     std::vector<AtomicCounterBuffer> mAtomicCounterBuffers;
     RangeUI mImageUniformRange;
     std::vector<InterfaceBlock> mComputeShaderStorageBlocks;

src/libANGLE/renderer/glslang_wrapper_utils.cpp

@@ -539,13 +539,70 @@ void AssignAttributeLocations(const gl::ProgramExecutable &programExecutable,
     }
 }
 
-void AssignOutputLocations(const gl::ProgramExecutable &programExecutable,
+void AssignSecondaryOutputLocations(const gl::ProgramState &programState,
+                                    ShaderInterfaceVariableInfoMap *variableInfoMapOut)
+{
+    const auto &secondaryOutputLocations =
+        programState.getExecutable().getSecondaryOutputLocations();
+    const auto &outputVariables = programState.getExecutable().getOutputVariables();
+
+    // Handle EXT_blend_func_extended secondary outputs (ones with index=1)
+    for (const gl::VariableLocation &outputLocation : secondaryOutputLocations)
+    {
+        if (outputLocation.arrayIndex == 0 && outputLocation.used() && !outputLocation.ignored)
+        {
+            const sh::ShaderVariable &outputVar = outputVariables[outputLocation.index];
+
+            uint32_t location = 0;
+            if (outputVar.location != -1)
+            {
+                location = outputVar.location;
+            }
+
+            ShaderInterfaceVariableInfo *info =
+                AddLocationInfo(variableInfoMapOut, gl::ShaderType::Fragment, outputVar.mappedName,
+                                location, ShaderInterfaceVariableInfo::kInvalid, 0, 0);
+
+            // If the shader source has not specified the index, specify it here.
+            if (outputVar.index == -1)
+            {
+                // Index 1 is used to specify that the color be used as the second color input to
+                // the blend equation
+                info->index = 1;
+            }
+        }
+    }
+    // Handle secondary outputs for ESSL version less than 3.00
+    gl::Shader *fragmentShader = programState.getAttachedShader(gl::ShaderType::Fragment);
+    if (fragmentShader && fragmentShader->getShaderVersion() == 100)
+    {
+        const auto &shaderOutputs = fragmentShader->getActiveOutputVariables();
+        for (const auto &outputVar : shaderOutputs)
+        {
+            if (outputVar.name == "gl_SecondaryFragColorEXT")
+            {
+                AddLocationInfo(variableInfoMapOut, gl::ShaderType::Fragment,
+                                "angle_SecondaryFragColor", 0,
+                                ShaderInterfaceVariableInfo::kInvalid, 0, 0);
+            }
+            else if (outputVar.name == "gl_SecondaryFragDataEXT")
+            {
+                AddLocationInfo(variableInfoMapOut, gl::ShaderType::Fragment,
+                                "angle_SecondaryFragData", 0, ShaderInterfaceVariableInfo::kInvalid,
+                                0, 0);
+            }
+        }
+    }
+}
+
+void AssignOutputLocations(const gl::ProgramState &programState,
                            const gl::ShaderType shaderType,
                            ShaderInterfaceVariableInfoMap *variableInfoMapOut)
 {
     // Assign output locations for the fragment shader.
     ASSERT(shaderType == gl::ShaderType::Fragment);
-    // TODO(syoussefi): Add support for EXT_blend_func_extended.  http://anglebug.com/3385
+
+    const gl::ProgramExecutable &programExecutable   = programState.getExecutable();
     const auto &outputLocations                      = programExecutable.getOutputLocations();
     const auto &outputVariables                      = programExecutable.getOutputVariables();
     const std::array<std::string, 3> implicitOutputs = {"gl_FragDepth", "gl_SampleMask",
@@ -576,6 +633,8 @@ void AssignOutputLocations(const gl::ProgramExecutable &programExecutable,
         }
     }
 
+    AssignSecondaryOutputLocations(programState, variableInfoMapOut);
+
     // When no fragment output is specified by the shader, the translator outputs webgl_FragColor or
     // webgl_FragData.  Add an entry for these.  Even though the translator is already assigning
     // location 0 to these entries, adding an entry for them here allows us to ASSERT that every
@@ -2223,6 +2282,13 @@ bool SpirvTransformer::transformDecorate(const uint32_t *instruction)
                              {spirv::LiteralInteger(info->component)});
     }
 
+    // Add index decoration, if any.
+    if (info->index != ShaderInterfaceVariableInfo::kInvalid)
+    {
+        spirv::WriteDecorate(mSpirvBlobOut, id, spv::DecorationIndex,
+                             {spirv::LiteralInteger(info->index)});
+    }
+
     // Add Xfb decorations, if any.
     if (mOptions.isTransformFeedbackStage &&
         info->xfb.buffer != ShaderInterfaceVariableXfbInfo::kInvalid)
@@ -3743,7 +3809,7 @@ void GlslangAssignLocations(const GlslangSourceOptions &options,
     if ((shaderType == gl::ShaderType::Fragment) &&
         programExecutable.hasLinkedShaderStage(gl::ShaderType::Fragment))
     {
-        AssignOutputLocations(programExecutable, gl::ShaderType::Fragment, variableInfoMapOut);
+        AssignOutputLocations(programState, gl::ShaderType::Fragment, variableInfoMapOut);
     }
 
     // Assign attributes to the vertex shader, if any.

src/libANGLE/renderer/glslang_wrapper_utils.h

@@ -97,6 +97,7 @@ struct ShaderInterfaceVariableInfo
     // locations in their respective slots.
     uint32_t location  = kInvalid;
     uint32_t component = kInvalid;
+    uint32_t index     = kInvalid;
     // The stages this shader interface variable is active.
     gl::ShaderBitSet activeStages;
     // Used for transform feedback extension to decorate vertex shader output.

src/libANGLE/renderer/vulkan/RendererVk.cpp

@@ -1545,6 +1545,8 @@ angle::Result RendererVk::initializeDevice(DisplayVk *displayVk, uint32_t queueF
     enabledFeatures.features.shaderCullDistance = mPhysicalDeviceFeatures.shaderCullDistance;
     // Used to support tessellation Shader:
     enabledFeatures.features.tessellationShader = mPhysicalDeviceFeatures.tessellationShader;
+    // Used to support EXT_blend_func_extended
+    enabledFeatures.features.dualSrcBlend = mPhysicalDeviceFeatures.dualSrcBlend;
 
     if (!vk::CommandBuffer::ExecutesInline())
     {

src/libANGLE/renderer/vulkan/vk_cache_utils.cpp

@@ -90,6 +90,14 @@ uint8_t PackGLBlendFactor(GLenum blendFactor)
             return static_cast<uint8_t>(VK_BLEND_FACTOR_ONE_MINUS_CONSTANT_COLOR);
         case GL_ONE_MINUS_CONSTANT_ALPHA:
             return static_cast<uint8_t>(VK_BLEND_FACTOR_ONE_MINUS_CONSTANT_ALPHA);
+        case GL_SRC1_COLOR_EXT:
+            return static_cast<uint8_t>(VK_BLEND_FACTOR_SRC1_COLOR);
+        case GL_SRC1_ALPHA_EXT:
+            return static_cast<uint8_t>(VK_BLEND_FACTOR_SRC1_ALPHA);
+        case GL_ONE_MINUS_SRC1_COLOR_EXT:
+            return static_cast<uint8_t>(VK_BLEND_FACTOR_ONE_MINUS_SRC1_COLOR);
+        case GL_ONE_MINUS_SRC1_ALPHA_EXT:
+            return static_cast<uint8_t>(VK_BLEND_FACTOR_ONE_MINUS_SRC1_ALPHA);
         default:
             UNREACHABLE();
             return 0;

src/libANGLE/renderer/vulkan/vk_caps_utils.cpp

@@ -997,6 +997,10 @@ void RendererVk::ensureCapsInitialized() const
             mNativeCaps.maxCombinedClipAndCullDistances = limitsVk.maxCombinedClipAndCullDistances;
         }
     }
+
+    // GL_EXT_blend_func_extended
+    mNativeExtensions.blendFuncExtended        = (mPhysicalDeviceFeatures.dualSrcBlend == VK_TRUE);
+    mNativeExtensions.maxDualSourceDrawBuffers = LimitToInt(limitsVk.maxFragmentDualSrcAttachments);
 }
 
 namespace vk

src/tests/gl_tests/BlendFuncExtendedTest.cpp

@@ -7,6 +7,7 @@
 //   Test EXT_blend_func_extended
 
 #include "test_utils/ANGLETest.h"
+#include "test_utils/gl_raii.h"
 
 #include "util/shader_utils.h"
 
@@ -134,13 +135,28 @@ class EXTBlendFuncExtendedDrawTest : public ANGLETest
         ASSERT_NE(0u, mProgram);
     }
 
+    virtual GLint getVertexAttribLocation(const char *name)
+    {
+        return glGetAttribLocation(mProgram, name);
+    }
+
+    virtual GLint getFragmentUniformLocation(const char *name)
+    {
+        return glGetUniformLocation(mProgram, name);
+    }
+
+    virtual void setUniform4f(GLint location, GLfloat v0, GLfloat v1, GLfloat v2, GLfloat v3)
+    {
+        glUniform4f(location, v0, v1, v2, v3);
+    }
+
     void drawTest()
     {
         glUseProgram(mProgram);
 
-        GLint position = glGetAttribLocation(mProgram, essl1_shaders::PositionAttrib());
-        GLint src0     = glGetUniformLocation(mProgram, "src0");
-        GLint src1     = glGetUniformLocation(mProgram, "src1");
+        GLint position = getVertexAttribLocation(essl1_shaders::PositionAttrib());
+        GLint src0     = getFragmentUniformLocation("src0");
+        GLint src1     = getFragmentUniformLocation("src1");
         ASSERT_GL_NO_ERROR();
 
         glBindBuffer(GL_ARRAY_BUFFER, mVBO);
@@ -152,8 +168,8 @@ class EXTBlendFuncExtendedDrawTest : public ANGLETest
         static const float kSrc0[4] = {1.0f, 1.0f, 1.0f, 1.0f};
         static const float kSrc1[4] = {0.3f, 0.6f, 0.9f, 0.7f};
 
-        glUniform4f(src0, kSrc0[0], kSrc0[1], kSrc0[2], kSrc0[3]);
-        glUniform4f(src1, kSrc1[0], kSrc1[1], kSrc1[2], kSrc1[3]);
+        setUniform4f(src0, kSrc0[0], kSrc0[1], kSrc0[2], kSrc0[3]);
+        setUniform4f(src1, kSrc1[0], kSrc1[1], kSrc1[2], kSrc1[3]);
         ASSERT_GL_NO_ERROR();
 
         glEnable(GL_BLEND);
@@ -216,7 +232,8 @@ class EXTBlendFuncExtendedDrawTestES3 : public EXTBlendFuncExtendedDrawTest
             mIsES31OrNewer = true;
         }
     }
-    void checkOutputIndexQuery(const char *name, GLint expectedIndex)
+
+    virtual void checkOutputIndexQuery(const char *name, GLint expectedIndex)
     {
         GLint index = glGetFragDataIndexEXT(mProgram, name);
         EXPECT_EQ(expectedIndex, index);
@@ -246,6 +263,109 @@ class EXTBlendFuncExtendedDrawTestES3 : public EXTBlendFuncExtendedDrawTest
     bool mIsES31OrNewer;
 };
 
+class EXTBlendFuncExtendedDrawTestES31 : public EXTBlendFuncExtendedDrawTestES3
+{
+  protected:
+    EXTBlendFuncExtendedDrawTestES31()
+        : EXTBlendFuncExtendedDrawTestES3(), mPipeline(0), mVertexProgram(0), mFragProgram(0)
+    {}
+
+    GLint getVertexAttribLocation(const char *name) override
+    {
+        return glGetAttribLocation(mVertexProgram, name);
+    }
+
+    GLint getFragmentUniformLocation(const char *name) override
+    {
+        return glGetUniformLocation(mFragProgram, name);
+    }
+
+    void setUniform4f(GLint location, GLfloat v0, GLfloat v1, GLfloat v2, GLfloat v3) override
+    {
+        glActiveShaderProgram(mPipeline, mFragProgram);
+        EXTBlendFuncExtendedDrawTest::setUniform4f(location, v0, v1, v2, v3);
+    }
+
+    void checkOutputIndexQuery(const char *name, GLint expectedIndex) override
+    {
+        GLint index = glGetFragDataIndexEXT(mFragProgram, name);
+        EXPECT_EQ(expectedIndex, index);
+        index = glGetProgramResourceLocationIndexEXT(mFragProgram, GL_PROGRAM_OUTPUT, name);
+        EXPECT_EQ(expectedIndex, index);
+    }
+
+    void setupProgramPipeline(const char *vertexSource, const char *fragmentSource)
+    {
+        mVertexProgram = createShaderProgram(GL_VERTEX_SHADER, vertexSource);
+        ASSERT_NE(mVertexProgram, 0u);
+        mFragProgram = createShaderProgram(GL_FRAGMENT_SHADER, fragmentSource);
+        ASSERT_NE(mFragProgram, 0u);
+
+        // Generate a program pipeline and attach the programs to their respective stages
+        glGenProgramPipelines(1, &mPipeline);
+        EXPECT_GL_NO_ERROR();
+        glUseProgramStages(mPipeline, GL_VERTEX_SHADER_BIT, mVertexProgram);
+        EXPECT_GL_NO_ERROR();
+        glUseProgramStages(mPipeline, GL_FRAGMENT_SHADER_BIT, mFragProgram);
+        EXPECT_GL_NO_ERROR();
+        glBindProgramPipeline(mPipeline);
+        EXPECT_GL_NO_ERROR();
+    }
+
+    GLuint createShaderProgram(GLenum type, const GLchar *shaderString)
+    {
+        GLShader shader(type);
+        if (!shader.get())
+        {
+            return 0;
+        }
+
+        glShaderSource(shader, 1, &shaderString, nullptr);
+        glCompileShader(shader);
+
+        GLuint program = glCreateProgram();
+
+        if (program)
+        {
+            GLint compiled;
+            glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+            glProgramParameteri(program, GL_PROGRAM_SEPARABLE, GL_TRUE);
+            if (compiled)
+            {
+                glAttachShader(program, shader);
+                glLinkProgram(program);
+                glDetachShader(program, shader);
+            }
+        }
+
+        EXPECT_GL_NO_ERROR();
+
+        return program;
+    }
+
+    void testTearDown() override
+    {
+        EXTBlendFuncExtendedDrawTest::testTearDown();
+        if (mVertexProgram)
+        {
+            glDeleteProgram(mVertexProgram);
+        }
+        if (mFragProgram)
+        {
+            glDeleteProgram(mFragProgram);
+        }
+        if (mPipeline)
+        {
+            glDeleteProgramPipelines(1, &mPipeline);
+        }
+
+        ASSERT_GL_NO_ERROR();
+    }
+
+    GLuint mPipeline;
+    GLuint mVertexProgram;
+    GLuint mFragProgram;
+};
 }  // namespace
 
 // Test EXT_blend_func_extended related gets.
@@ -287,6 +407,12 @@ TEST_P(EXTBlendFuncExtendedDrawTest, FragData)
 {
     ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_EXT_blend_func_extended"));
 
+    // Suspected VK driver bug http://anglebug.com/5523
+    ANGLE_SKIP_TEST_IF(IsVulkan() && (IsNVIDIA() || IsPixel2()));
+
+    // Suspected AMD VK driver bug http://anglebug.com/5537
+    ANGLE_SKIP_TEST_IF(IsVulkan() && IsWindows() && IsAMD());
+
     const char *kFragColorShader =
         "#extension GL_EXT_blend_func_extended : require\n"
         "precision mediump float;\n"
@@ -396,6 +522,9 @@ TEST_P(EXTBlendFuncExtendedDrawTestES3, FragmentArrayOutputLocationsAPI)
     // TODO: Investigate this mac-only failure.  http://angleproject.com/1085
     ANGLE_SKIP_TEST_IF(IsOSX());
 
+    // Suspected VK driver bug http://anglebug.com/5523
+    ANGLE_SKIP_TEST_IF(IsVulkan() && (IsNVIDIA() || IsPixel2()));
+
     constexpr char kFS[] = R"(#version 300 es
 #extension GL_EXT_blend_func_extended : require
 precision mediump float;
@@ -708,8 +837,103 @@ void main() {
     glDeleteProgram(program);
 }
 
+// Use a program pipeline with EXT_blend_func_extended
+TEST_P(EXTBlendFuncExtendedDrawTestES31, UseProgramPipeline)
+{
+    // Only the Vulkan backend supports PPO
+    ANGLE_SKIP_TEST_IF(!IsVulkan());
+
+    // Create two separable program objects from a
+    // single source string respectively (vertSrc and fragSrc)
+    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_EXT_blend_func_extended"));
+
+    const char *kFragColorShader = R"(#version 300 es
+#extension GL_EXT_blend_func_extended : require
+precision mediump float;
+uniform vec4 src0;
+uniform vec4 src1;
+layout(location = 0, index = 1) out vec4 outSrc1;
+layout(location = 0, index = 0) out vec4 outSrc0;
+void main() {
+    outSrc0 = src0;
+    outSrc1 = src1;
+})";
+
+    setupProgramPipeline(essl3_shaders::vs::Simple(), kFragColorShader);
+
+    checkOutputIndexQuery("outSrc0", 0);
+    checkOutputIndexQuery("outSrc1", 1);
+
+    ASSERT_EQ(mProgram, 0u);
+    drawTest();
+
+    ASSERT_GL_NO_ERROR();
+}
+
+// Use program pipeline where the fragment program is changed
+TEST_P(EXTBlendFuncExtendedDrawTestES31, UseTwoProgramStages)
+{
+    // Only the Vulkan backend supports PPO
+    ANGLE_SKIP_TEST_IF(!IsVulkan());
+
+    // Create two separable program objects from a
+    // single source string respectively (vertSrc and fragSrc)
+    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_EXT_blend_func_extended"));
+
+    const char *kFragColorShaderFlipped = R"(#version 300 es
+#extension GL_EXT_blend_func_extended : require
+precision mediump float;
+uniform vec4 src0;
+uniform vec4 src1;
+layout(location = 0, index = 0) out vec4 outSrc1;
+layout(location = 0, index = 1) out vec4 outSrc0;
+void main() {
+    outSrc0 = src0;
+    outSrc1 = src1;
+})";
+
+    const char *kFragColorShader = R"(#version 300 es
+#extension GL_EXT_blend_func_extended : require
+precision mediump float;
+uniform vec4 src0;
+uniform vec4 src1;
+layout(location = 0, index = 1) out vec4 outSrc1;
+layout(location = 0, index = 0) out vec4 outSrc0;
+void main() {
+    outSrc0 = src0;
+    outSrc1 = src1;
+})";
+
+    setupProgramPipeline(essl3_shaders::vs::Simple(), kFragColorShaderFlipped);
+
+    // Check index values frag shader with the "flipped" index values
+    checkOutputIndexQuery("outSrc0", 1);
+    checkOutputIndexQuery("outSrc1", 0);
+
+    GLuint previousProgram = mFragProgram;
+    mFragProgram           = createShaderProgram(GL_FRAGMENT_SHADER, kFragColorShader);
+    ASSERT_NE(mFragProgram, 0u);
+
+    // Change the Fragment program of the pipeline
+    glUseProgramStages(mPipeline, GL_FRAGMENT_SHADER_BIT, mFragProgram);
+    EXPECT_GL_NO_ERROR();
+
+    checkOutputIndexQuery("outSrc0", 0);
+    checkOutputIndexQuery("outSrc1", 1);
+
+    ASSERT_EQ(mProgram, 0u);
+    drawTest();
+
+    if (previousProgram)
+    {
+        glDeleteProgram(previousProgram);
+    }
+    ASSERT_GL_NO_ERROR();
+}
+
 ANGLE_INSTANTIATE_TEST_ES2(EXTBlendFuncExtendedTest);
 ANGLE_INSTANTIATE_TEST_ES3_AND_ES31(EXTBlendFuncExtendedTestES3);
 
 ANGLE_INSTANTIATE_TEST_ES2(EXTBlendFuncExtendedDrawTest);
 ANGLE_INSTANTIATE_TEST_ES3_AND_ES31(EXTBlendFuncExtendedDrawTestES3);
+ANGLE_INSTANTIATE_TEST_ES31(EXTBlendFuncExtendedDrawTestES31);