Vulkan: Implement ES 3.0 rasterizer discard

Rasterizer discard is a feature that allows the graphics pipeline
to skip the fragment shader stage.

Implementing rasterizer discard in Vulkan is as easy as not binding
a fragment shader binary.

Tests for rasterizer discard live in
dEQP-GLES3.functional.rasterizer_discard.*.

Bug: angleproject:3214
Test: dEQP-GLES3.functional.rasterizer_discard.*
Change-Id: I0815df3b70f6f9cdc6c8c87ec4813bb629d8bd5f
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1646692
Commit-Queue: Tim Van Patten <timvp@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

Author: timvpGoogle

src/libANGLE/renderer/vulkan/ContextVk.cpp

@@ -1495,6 +1495,8 @@ angle::Result ContextVk::syncState(const gl::Context *context,
                                                            glState.getRasterizerState());
                 break;
             case gl::State::DIRTY_BIT_RASTERIZER_DISCARD_ENABLED:
+                mGraphicsPipelineDesc->updateRasterizerDiscardEnabled(
+                    &mGraphicsPipelineTransition, glState.isRasterizerDiscardEnabled());
                 break;
             case gl::State::DIRTY_BIT_LINE_WIDTH:
                 mGraphicsPipelineDesc->updateLineWidth(&mGraphicsPipelineTransition,

src/libANGLE/renderer/vulkan/vk_cache_utils.cpp

@@ -595,7 +595,8 @@ angle::Result GraphicsPipelineDesc::initializePipeline(
     shaderStages.push_back(vertexStage);
 
     // Fragment shader is optional.
-    if (fragmentModule)
+    // anglebug.com/3509 - Don't compile the fragment shader if rasterizationDiscardEnable = true
+    if (fragmentModule && !mRasterizationAndMultisampleStateInfo.bits.rasterizationDiscardEnable)
     {
         VkPipelineShaderStageCreateInfo fragmentStage = {};
         fragmentStage.sType               = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
@@ -853,6 +854,15 @@ void GraphicsPipelineDesc::updateLineWidth(GraphicsPipelineTransitionBits *trans
     transition->set(ANGLE_GET_TRANSITION_BIT(mRasterizationAndMultisampleStateInfo, lineWidth));
 }
 
+void GraphicsPipelineDesc::updateRasterizerDiscardEnabled(
+    GraphicsPipelineTransitionBits *transition,
+    bool rasterizerDiscardEnabled)
+{
+    mRasterizationAndMultisampleStateInfo.bits.rasterizationDiscardEnable =
+        static_cast<uint32_t>(rasterizerDiscardEnabled);
+    transition->set(ANGLE_GET_TRANSITION_BIT(mRasterizationAndMultisampleStateInfo, bits));
+}
+
 void GraphicsPipelineDesc::setRasterizationSamples(uint32_t rasterizationSamples)
 {
     mRasterizationAndMultisampleStateInfo.bits.rasterizationSamples = rasterizationSamples;

src/libANGLE/renderer/vulkan/vk_cache_utils.h

@@ -383,6 +383,8 @@ class GraphicsPipelineDesc final
                          const gl::RasterizerState &rasterState,
                          bool invertFrontFace);
     void updateLineWidth(GraphicsPipelineTransitionBits *transition, float lineWidth);
+    void updateRasterizerDiscardEnabled(GraphicsPipelineTransitionBits *transition,
+                                        bool rasterizerDiscardEnabled);
 
     // Multisample states
     void setRasterizationSamples(uint32_t rasterizationSamples);

src/tests/deqp_support/deqp_gles3_test_expectations.txt

@@ -685,7 +685,6 @@
 2976 VULKAN NVIDIA : dEQP-GLES3.functional.shaders.invariance.* = FAIL
 
 // To be triaged:
-2950 VULKAN : dEQP-GLES3.functional.rasterizer_discard.* = SKIP
 2950 VULKAN : dEQP-GLES3.functional.negative_api.vertex_array.draw_element* = SKIP
 
 // Android Vulkan failures

src/tests/gl_tests/StateChangeTest.cpp

@@ -2385,6 +2385,9 @@ TEST_P(SimpleStateChangeTest, ReleaseShaderInUseThatReadsFromUniforms)
 // Tests that sampler sync isn't masked by program textures.
 TEST_P(SimpleStateChangeTestES3, SamplerSyncNotTiedToProgram)
 {
+    // glBindSampler is available only if the GLES version is 3.0 or higher - anglebug.com/3208
+    ANGLE_SKIP_TEST_IF(IsVulkan());
+
     // Create a sampler with NEAREST filtering.
     GLSampler sampler;
     glBindSampler(0, sampler);
@@ -3726,6 +3729,39 @@ TEST_P(SimpleStateChangeTest, FboLateCullFaceBackCWState)
 {
     drawToFboWithCulling(GL_CW, false);
 }
+
+// Validates GL_RASTERIZER_DISCARD state is tracked correctly
+TEST_P(SimpleStateChangeTestES3, RasterizerDiscardState)
+{
+    glClearColor(GLColor::red.R, GLColor::red.G, GLColor::red.B, GLColor::red.A);
+    glClear(GL_COLOR_BUFFER_BIT);
+    ASSERT_GL_NO_ERROR();
+    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
+
+    ANGLE_GL_PROGRAM(greenProgram, essl1_shaders::vs::Simple(), essl1_shaders::fs::Green());
+    ANGLE_GL_PROGRAM(blueProgram, essl1_shaders::vs::Simple(), essl1_shaders::fs::Blue());
+
+    // The drawQuad() should have no effect with GL_RASTERIZER_DISCARD enabled
+    glEnable(GL_RASTERIZER_DISCARD);
+    glUseProgram(greenProgram);
+    drawQuad(greenProgram.get(), std::string(essl1_shaders::PositionAttrib()), 0.0f);
+    ASSERT_GL_NO_ERROR();
+    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
+
+    // The drawQuad() should draw something with GL_RASTERIZER_DISCARD disabled
+    glDisable(GL_RASTERIZER_DISCARD);
+    glUseProgram(greenProgram);
+    drawQuad(greenProgram.get(), std::string(essl1_shaders::PositionAttrib()), 0.0f);
+    ASSERT_GL_NO_ERROR();
+    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
+
+    // The drawQuad() should have no effect with GL_RASTERIZER_DISCARD enabled
+    glEnable(GL_RASTERIZER_DISCARD);
+    glUseProgram(blueProgram);
+    drawQuad(blueProgram.get(), std::string(essl1_shaders::PositionAttrib()), 0.0f);
+    ASSERT_GL_NO_ERROR();
+    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
+}
 }  // anonymous namespace
 
 ANGLE_INSTANTIATE_TEST(StateChangeTest, ES2_D3D9(), ES2_D3D11(), ES2_OPENGL(), ES2_VULKAN());
@@ -3737,7 +3773,7 @@ ANGLE_INSTANTIATE_TEST(LineLoopStateChangeTest,
 ANGLE_INSTANTIATE_TEST(StateChangeRenderTest, ES2_D3D9(), ES2_D3D11(), ES2_OPENGL(), ES2_VULKAN());
 ANGLE_INSTANTIATE_TEST(StateChangeTestES3, ES3_D3D11(), ES3_OPENGL());
 ANGLE_INSTANTIATE_TEST(SimpleStateChangeTest, ES2_D3D11(), ES2_VULKAN(), ES2_OPENGL());
-ANGLE_INSTANTIATE_TEST(SimpleStateChangeTestES3, ES3_OPENGL(), ES3_D3D11());
+ANGLE_INSTANTIATE_TEST(SimpleStateChangeTestES3, ES3_OPENGL(), ES3_D3D11(), ES3_VULKAN());
 ANGLE_INSTANTIATE_TEST(SimpleStateChangeTestES31, ES31_OPENGL(), ES31_D3D11());
 ANGLE_INSTANTIATE_TEST(ValidationStateChangeTest, ES3_D3D11(), ES3_OPENGL());
 ANGLE_INSTANTIATE_TEST(WebGL2ValidationStateChangeTest, ES3_D3D11(), ES3_OPENGL());