Vulkan: No line raster emulation code if extension

include/GLSLANG/ShaderLang.h

@@ -26,7 +26,7 @@
 
 // Version number for shader translation API.
 // It is incremented every time the API changes.
-#define ANGLE_SH_VERSION 221
+#define ANGLE_SH_VERSION 222
 
 enum ShShaderSpec
 {
@@ -318,6 +318,11 @@ const ShCompileOptions SH_REMOVE_DYNAMIC_INDEXING_OF_SWIZZLED_VECTOR = UINT64_C(
 // on Windows 7 and earlier.
 const ShCompileOptions SH_DONT_TRANSLATE_UNIFORM_BLOCK_TO_STRUCTUREDBUFFER = UINT64_C(1) << 50;
 
+// This flag indicates whether Bresenham line raster emulation code should be generated.  This
+// emulation is necessary if the backend uses a differnet algorithm to draw lines.  Currently only
+// implemented for the Vulkan backend.
+const ShCompileOptions SH_ADD_BRESENHAM_LINE_RASTER_EMULATION = UINT64_C(1) << 51;
+
 // Defines alternate strategies for implementing array index clamping.
 enum ShArrayIndexClampingStrategy
 {

src/compiler/translator/TranslatorVulkan.cpp

@@ -870,10 +870,13 @@ bool TranslatorVulkan::translateImpl(TIntermBlock *root,
             }
         }
 
-        if (!AddBresenhamEmulationFS(this, sink, root, &getSymbolTable(), driverUniforms,
-                                     usesFragCoord))
+        if (compileOptions & SH_ADD_BRESENHAM_LINE_RASTER_EMULATION)
         {
-            return false;
+            if (!AddBresenhamEmulationFS(this, sink, root, &getSymbolTable(), driverUniforms,
+                                         usesFragCoord))
+            {
+                return false;
+            }
         }
 
         bool hasGLFragColor = false;
@@ -936,9 +939,12 @@ bool TranslatorVulkan::translateImpl(TIntermBlock *root,
     }
     else if (getShaderType() == GL_VERTEX_SHADER)
     {
-        if (!AddBresenhamEmulationVS(this, root, &getSymbolTable(), driverUniforms))
+        if (compileOptions & SH_ADD_BRESENHAM_LINE_RASTER_EMULATION)
         {
-            return false;
+            if (!AddBresenhamEmulationVS(this, root, &getSymbolTable(), driverUniforms))
+            {
+                return false;
+            }
         }
 
         // Add a macro to declare transform feedback buffers.

src/libANGLE/renderer/vulkan/ShaderVk.cpp

@@ -40,6 +40,11 @@ std::shared_ptr<WaitableCompileEvent> ShaderVk::compile(const gl::Context *conte
         compileOptions |= SH_CLAMP_POINT_SIZE;
     }
 
+    if (contextVk->getFeatures().basicGLLineRasterization.enabled)
+    {
+        compileOptions |= SH_ADD_BRESENHAM_LINE_RASTER_EMULATION;
+    }
+
     if (contextVk->emulateSeamfulCubeMapSampling())
     {
         compileOptions |= SH_EMULATE_SEAMFUL_CUBE_MAP_SAMPLING;