command_buffer: Use GLSL core version that matches the OpenGL version

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index fba0b90ed602633fe7e2a6d5b1fb67304fa51fa9..22b58c00ae3112c671b57b8d8aa88a3053953263 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -218,6 +218,50 @@ bool CombineAdjacentRects(const gfx::Rect& rect1,
   return false;
 }
 
+ShShaderOutput GetShaderOutputLanguageForContext(

[Ken Russell (switch to Gerrit), 2015/08/05 18:29:37]

Please figure out some way to test this code. Perhaps you could expose it in
gles2_cmd_decoder.h as a static "ForTesting" method, and add tests of the
version string handling to gles2_cmd_decoder_unittest.cc -- or go through the
whole command decoder initialization (which sounds like overkill).

[Kimmo Kinnunen, 2015/08/10 08:36:34]

I struggled a bit adding the return type (ShShaderOutput) to the decoder.h.
Maybe the posted alternative would be ok?

+    const gfx::GLVersionInfo& version_info) {
+  if (version_info.is_es) {
+    return SH_ESSL_OUTPUT;
+  }
+
+  // Determine the GLSL version based on OpenGL specification.
+
+  unsigned context_version =
+      version_info.major_version * 100 + version_info.minor_version * 10;
+  if (context_version >= 450) {
+    // OpenGL specs from 4.2 on specify that the core profile is "also
+    // guaranteed to support all previous versions of the OpenGL Shading
+    // Language back to version 1.40". For simplicity, we assume future
+    // specs do not unspecify this. If they did, they could unspecify
+    // glGetStringi(GL_SHADING_LANGUAGE_VERSION, k), too.
+    // Since current context >= 4.5, use GLSL 4.50 core.
+    return SH_GLSL_450_CORE_OUTPUT;
+  } else if (context_version == 440) {
+      return SH_GLSL_440_CORE_OUTPUT;
+  } else if (context_version == 430) {
+      return SH_GLSL_430_CORE_OUTPUT;
+  } else if (context_version == 420) {
+      return SH_GLSL_420_CORE_OUTPUT;
+  } else if (context_version == 410) {
+      return SH_GLSL_410_CORE_OUTPUT;
+  } else if (context_version == 400) {
+      return SH_GLSL_400_CORE_OUTPUT;
+  } else if (context_version == 330) {
+      return SH_GLSL_330_CORE_OUTPUT;
+  } else if (context_version == 320) {
+      return SH_GLSL_150_CORE_OUTPUT;
+  } else if (context_version == 310) {
+      return SH_GLSL_140_OUTPUT;
+  } else if (context_version == 300) {
+      return SH_GLSL_130_OUTPUT;
+  }
+
+  // Before OpenGL 3.0 we use compatibility profile. Also for future
+  // specs between OpenGL 3.3 and OpenGL 4.0, at the time of writing,
+  // we use compatibility profile.
+  return SH_GLSL_COMPATIBILITY_OUTPUT;
+}
+
 }  // namespace
 
 class GLES2DecoderImpl;
@@ -3239,9 +3283,10 @@ bool GLES2DecoderImpl::InitializeShaderTranslator() {
     resources.HashFunction = &CityHash64;
   else
     resources.HashFunction = NULL;
-  ShaderTranslatorInterface::GlslImplementationType implementation_type =
-      gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2 ?
-          ShaderTranslatorInterface::kGlslES : ShaderTranslatorInterface::kGlsl;
+
+  ShShaderOutput shader_output_language =
+      GetShaderOutputLanguageForContext(feature_info_->gl_version_info());
+
   int driver_bug_workarounds = 0;
   if (workarounds().needs_glsl_built_in_function_emulation)
     driver_bug_workarounds |= SH_EMULATE_BUILT_IN_FUNCTIONS;
@@ -3265,10 +3310,7 @@ bool GLES2DecoderImpl::InitializeShaderTranslator() {
     resources.WEBGL_debug_shader_precision = true;
 
   vertex_translator_ = shader_translator_cache()->GetTranslator(
-      GL_VERTEX_SHADER,
-      shader_spec,
-      &resources,
-      implementation_type,
+      GL_VERTEX_SHADER, shader_spec, &resources, shader_output_language,
       static_cast<ShCompileOptions>(driver_bug_workarounds));
   if (!vertex_translator_.get()) {
     LOG(ERROR) << "Could not initialize vertex shader translator.";
@@ -3277,10 +3319,7 @@ bool GLES2DecoderImpl::InitializeShaderTranslator() {
   }
 
   fragment_translator_ = shader_translator_cache()->GetTranslator(
-      GL_FRAGMENT_SHADER,
-      shader_spec,
-      &resources,
-      implementation_type,
+      GL_FRAGMENT_SHADER, shader_spec, &resources, shader_output_language,
       static_cast<ShCompileOptions>(driver_bug_workarounds));
   if (!fragment_translator_.get()) {
     LOG(ERROR) << "Could not initialize fragment shader translator.";