Init PointSize value when pipeline topology is PointList in end2end

When pipeline topology is set to Point_List, PointSize must be written
in vertex shader for Vulkan backend.

BUG=dawn:146

Change-Id: Id5aac73bb7e60646503f1ea06c2aa0d39c8384b3
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7820
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>

src/dawn_native/d3d12/ShaderModuleD3D12.cpp

@@ -42,6 +42,13 @@ namespace dawn_native { namespace d3d12 {
 
         spirv_cross::CompilerHLSL::Options options_hlsl;
         options_hlsl.shader_model = 51;
+        // PointCoord and PointSize are not supported in HLSL
+        // TODO (hao.x.li@intel.com): The point_coord_compat and point_size_compat are
+        // required temporarily for https://bugs.chromium.org/p/dawn/issues/detail?id=146,
+        // but should be removed once WebGPU requires there is no gl_PointSize builtin.
+        // See https://github.com/gpuweb/gpuweb/issues/332
+        options_hlsl.point_coord_compat = true;
+        options_hlsl.point_size_compat = true;
         compiler.set_hlsl_options(options_hlsl);
 
         const ModuleBindingInfo& moduleBindingInfo = GetBindingInfo();

src/dawn_native/metal/ShaderModuleMTL.mm

@@ -58,6 +58,15 @@ namespace dawn_native { namespace metal {
         options_glsl.vertex.flip_vert_y = true;
         compiler.spirv_cross::CompilerGLSL::set_common_options(options_glsl);
 
+        // Disable PointSize builtin for https://bugs.chromium.org/p/dawn/issues/detail?id=146
+        // Becuase Metal will reject PointSize builtin if the shader is compiled into a render
+        // pipeline that uses a non-point topology.
+        // TODO (hao.x.li@intel.com): Remove this once WebGPU requires there is no
+        // gl_PointSize builtin (https://github.com/gpuweb/gpuweb/issues/332).
+        spirv_cross::CompilerMSL::Options options_msl;
+        options_msl.enable_point_size_builtin = false;
+        compiler.set_msl_options(options_msl);
+
         // By default SPIRV-Cross will give MSL resources indices in increasing order.
         // To make the MSL indices match the indices chosen in the PipelineLayout, we build
         // a table of MSLResourceBinding to give to SPIRV-Cross.

src/fuzzers/DawnSPIRVCrossHLSLFastFuzzer.cpp

@@ -34,6 +34,12 @@ namespace {
             // Using the options that are used by Dawn, they appear in ShaderModuleD3D12.cpp
             options.SetFlipVertY(true);
             options.SetHLSLShaderModel(51);
+            // TODO (hao.x.li@intel.com): The HLSLPointCoordCompat and HLSLPointSizeCompat are
+            // required temporarily for https://bugs.chromium.org/p/dawn/issues/detail?id=146,
+            // but should be removed once WebGPU requires there is no gl_PointSize builtin.
+            // See https://github.com/gpuweb/gpuweb/issues/332
+            options.SetHLSLPointCoordCompat(true);
+            options.SetHLSLPointSizeCompat(true);
             compiler.CompileSpvToHlsl(input.data(), input.size(), options);
         });
 

src/tests/end2end/PrimitiveTopologyTests.cpp

@@ -155,8 +155,8 @@ class PrimitiveTopologyTest : public DawnTest {
                 layout(location = 0) in vec4 pos;
                 void main() {
                     gl_Position = pos;
-                })"
-            );
+                    gl_PointSize = 1.0;
+                })");
 
             fsModule = utils::CreateShaderModule(device, dawn::ShaderStage::Fragment, R"(
                 #version 450

src/tests/end2end/ViewportOrientationTests.cpp

@@ -27,6 +27,7 @@ TEST_P(ViewportOrientationTests, OriginAt0x0) {
         #version 450
         void main() {
             gl_Position = vec4(-0.5f, -0.5f, 0.0f, 1.0f);
+            gl_PointSize = 1.0;
         })");
 
     dawn::ShaderModule fsModule = utils::CreateShaderModule(device, dawn::ShaderStage::Fragment, R"(