Quelle  GLContext.cpp   Sprache: C

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "GLContext.h"

#include <algorithm>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <regex>
#include <string>
#include <vector>
#ifdef MOZ_WIDGET_ANDROID
#  include <sys/mman.h>
#endif
#if defined(XP_LINUX) && !defined(ANDROID)
// For MesaMemoryLeakWorkaround
#  include <dlfcn.h>
#  include <link.h>
#endif

#include "GLBlitHelper.h"
#include "GLReadTexImageHelper.h"
#include "GLScreenBuffer.h"

#include "gfxCrashReporterUtils.h"
#include "gfxEnv.h"
#include "gfxUtils.h"
#include "GLContextProvider.h"
#include "GLLibraryLoader.h"
#include "GLTextureImage.h"
#include "nsPrintfCString.h"
#include "nsThreadUtils.h"
#include "prenv.h"
#include "prlink.h"
#include "ScopedGLHelpers.h"
#include "SharedSurfaceGL.h"
#include "GfxTexturesReporter.h"
#include "gfx2DGlue.h"
#include "mozilla/StaticPrefs_gfx.h"
#include "mozilla/StaticPrefs_gl.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/gfx/Logging.h"
#include "mozilla/layers/BuildConstants.h"
#include "mozilla/layers/TextureForwarder.h"  // for LayersIPCChannel

#include "OGLShaderProgram.h"  // for ShaderProgramType

#include "mozilla/DebugOnly.h"
#include "mozilla/Maybe.h"

#ifdef XP_MACOSX
#  include <CoreServices/CoreServices.h>
#endif

#ifdef MOZ_WIDGET_ANDROID
#  include "mozilla/jni/Utils.h"
#endif

namespace mozilla {
namespace gl {

using namespace mozilla::gfx;
using namespace mozilla::layers;

// Zero-initialized after init().
MOZ_THREAD_LOCAL(const GLContext*) GLContext::sCurrentContext;

// If adding defines, don't forget to undefine symbols. See #undef block below.
// clang-format off
#define CORE_SYMBOL(x) { (PRFuncPtr*) &mSymbols.f##x, {{ "gl" #x }} }
#define CORE_EXT_SYMBOL2(x,y,z) { (PRFuncPtr*) &mSymbols.f##x, {{ "gl" #x, "gl" #x #y, "gl" #x #z }} }
#define EXT_SYMBOL2(x,y,z) { (PRFuncPtr*) &mSymbols.f##x, {{ "gl" #x #y, "gl" #x #z }} }
#define EXT_SYMBOL3(x,y,z,w) { (PRFuncPtr*) &mSymbols.f##x, {{ "gl" #x #y, "gl" #x #z, "gl" #x #w }} }
#define END_SYMBOLS { nullptr, {} }
// clang-format on

// should match the order of GLExtensions, and be null-terminated.
static const char* const sExtensionNames[] = {
    "NO_EXTENSION",
    "GL_AMD_compressed_ATC_texture",
    "GL_ANGLE_depth_texture",
    "GL_ANGLE_framebuffer_blit",
    "GL_ANGLE_framebuffer_multisample",
    "GL_ANGLE_instanced_arrays",
    "GL_ANGLE_multiview",
    "GL_ANGLE_provoking_vertex",
    "GL_ANGLE_texture_compression_dxt3",
    "GL_ANGLE_texture_compression_dxt5",
    "GL_ANGLE_timer_query",
    "GL_APPLE_client_storage",
    "GL_APPLE_fence",
    "GL_APPLE_framebuffer_multisample",
    "GL_APPLE_sync",
    "GL_APPLE_texture_range",
    "GL_APPLE_vertex_array_object",
    "GL_ARB_ES2_compatibility",
    "GL_ARB_ES3_compatibility",
    "GL_ARB_color_buffer_float",
    "GL_ARB_compatibility",
    "GL_ARB_copy_buffer",
    "GL_ARB_depth_clamp",
    "GL_ARB_depth_texture",
    "GL_ARB_draw_buffers",
    "GL_ARB_draw_instanced",
    "GL_ARB_framebuffer_object",
    "GL_ARB_framebuffer_sRGB",
    "GL_ARB_geometry_shader4",
    "GL_ARB_half_float_pixel",
    "GL_ARB_instanced_arrays",
    "GL_ARB_internalformat_query",
    "GL_ARB_invalidate_subdata",
    "GL_ARB_map_buffer_range",
    "GL_ARB_occlusion_query2",
    "GL_ARB_pixel_buffer_object",
    "GL_ARB_provoking_vertex",
    "GL_ARB_robust_buffer_access_behavior",
    "GL_ARB_robustness",
    "GL_ARB_sampler_objects",
    "GL_ARB_seamless_cube_map",
    "GL_ARB_shader_texture_lod",
    "GL_ARB_sync",
    "GL_ARB_texture_compression",
    "GL_ARB_texture_compression_bptc",
    "GL_ARB_texture_compression_rgtc",
    "GL_ARB_texture_float",
    "GL_ARB_texture_non_power_of_two",
    "GL_ARB_texture_rectangle",
    "GL_ARB_texture_rg",
    "GL_ARB_texture_storage",
    "GL_ARB_texture_swizzle",
    "GL_ARB_timer_query",
    "GL_ARB_transform_feedback2",
    "GL_ARB_uniform_buffer_object",
    "GL_ARB_vertex_array_object",
    "GL_CHROMIUM_color_buffer_float_rgb",
    "GL_CHROMIUM_color_buffer_float_rgba",
    "GL_EXT_bgra",
    "GL_EXT_blend_minmax",
    "GL_EXT_color_buffer_float",
    "GL_EXT_color_buffer_half_float",
    "GL_EXT_copy_texture",
    "GL_EXT_depth_clamp",
    "GL_EXT_disjoint_timer_query",
    "GL_EXT_draw_buffers",
    "GL_EXT_draw_buffers2",
    "GL_EXT_draw_instanced",
    "GL_EXT_float_blend",
    "GL_EXT_frag_depth",
    "GL_EXT_framebuffer_blit",
    "GL_EXT_framebuffer_multisample",
    "GL_EXT_framebuffer_object",
    "GL_EXT_framebuffer_sRGB",
    "GL_EXT_gpu_shader4",
    "GL_EXT_map_buffer_range",
    "GL_EXT_multisampled_render_to_texture",
    "GL_EXT_occlusion_query_boolean",
    "GL_EXT_packed_depth_stencil",
    "GL_EXT_provoking_vertex",
    "GL_EXT_read_format_bgra",
    "GL_EXT_robustness",
    "GL_EXT_sRGB",
    "GL_EXT_sRGB_write_control",
    "GL_EXT_shader_texture_lod",
    "GL_EXT_texture_compression_bptc",
    "GL_EXT_texture_compression_dxt1",
    "GL_EXT_texture_compression_rgtc",
    "GL_EXT_texture_compression_s3tc",
    "GL_EXT_texture_compression_s3tc_srgb",
    "GL_EXT_texture_filter_anisotropic",
    "GL_EXT_texture_format_BGRA8888",
    "GL_EXT_texture_norm16",
    "GL_EXT_texture_sRGB",
    "GL_EXT_texture_storage",
    "GL_EXT_timer_query",
    "GL_EXT_transform_feedback",
    "GL_EXT_unpack_subimage",
    "GL_EXT_semaphore",
    "GL_EXT_semaphore_fd",
    "GL_EXT_memory_object",
    "GL_EXT_memory_object_fd",
    "GL_IMG_read_format",
    "GL_IMG_texture_compression_pvrtc",
    "GL_IMG_texture_npot",
    "GL_KHR_debug",
    "GL_KHR_parallel_shader_compile",
    "GL_KHR_robust_buffer_access_behavior",
    "GL_KHR_robustness",
    "GL_KHR_texture_compression_astc_hdr",
    "GL_KHR_texture_compression_astc_ldr",
    "GL_NV_draw_instanced",
    "GL_NV_fence",
    "GL_NV_framebuffer_blit",
    "GL_NV_geometry_program4",
    "GL_NV_half_float",
    "GL_NV_instanced_arrays",
    "GL_NV_primitive_restart",
    "GL_NV_texture_barrier",
    "GL_NV_transform_feedback",
    "GL_NV_transform_feedback2",
    "GL_OES_EGL_image",
    "GL_OES_EGL_image_external",
    "GL_OES_EGL_sync",
    "GL_OES_compressed_ETC1_RGB8_texture",
    "GL_OES_depth24",
    "GL_OES_depth32",
    "GL_OES_depth_texture",
    "GL_OES_draw_buffers_indexed",
    "GL_OES_element_index_uint",
    "GL_OES_fbo_render_mipmap",
    "GL_OES_framebuffer_object",
    "GL_OES_packed_depth_stencil",
    "GL_OES_rgb8_rgba8",
    "GL_OES_standard_derivatives",
    "GL_OES_stencil8",
    "GL_OES_texture_3D",
    "GL_OES_texture_float",
    "GL_OES_texture_float_linear",
    "GL_OES_texture_half_float",
    "GL_OES_texture_half_float_linear",
    "GL_OES_texture_npot",
    "GL_OES_vertex_array_object",
    "GL_OVR_multiview2"};

static bool ShouldUseTLSIsCurrent(bool useTLSIsCurrent) {
  if (StaticPrefs::gl_use_tls_is_current() == 0) {
    return useTLSIsCurrent;
  }

  return StaticPrefs::gl_use_tls_is_current() > 0;
}

static bool ParseVersion(const std::string& versionStr,
                         uint32_t* const out_major, uint32_t* const out_minor) {
  static const std::regex kVersionRegex("([0-9]+)\\.([0-9]+)");
  std::smatch match;
  if (!std::regex_search(versionStr, match, kVersionRegex)) return false;

  const auto& majorStr = match.str(1);
  const auto& minorStr = match.str(2);
  *out_major = atoi(majorStr.c_str());
  *out_minor = atoi(minorStr.c_str());
  return true;
}

/*static*/
uint8_t GLContext::ChooseDebugFlags(const CreateContextFlags createFlags) {
  uint8_t debugFlags = 0;

#ifdef MOZ_GL_DEBUG_BUILD
  if (gfxEnv::MOZ_GL_DEBUG()) {
    debugFlags |= GLContext::DebugFlagEnabled;
  }

  // Enables extra verbose output, informing of the start and finish of every GL
  // call. Useful e.g. to record information to investigate graphics system
  // crashes/lockups
  if (gfxEnv::MOZ_GL_DEBUG_VERBOSE()) {
    debugFlags |= GLContext::DebugFlagTrace;
  }

  // Aborts on GL error. Can be useful to debug quicker code that is known not
  // to generate any GL error in principle.
  bool abortOnError = false;

  if (createFlags & CreateContextFlags::NO_VALIDATION) {
    abortOnError = true;

    const auto& env = gfxEnv::MOZ_GL_DEBUG_ABORT_ON_ERROR();
    if (env.as_str == "0") {
      abortOnError = false;
    }
  }

  if (abortOnError) {
    debugFlags |= GLContext::DebugFlagAbortOnError;
  }
#endif

  return debugFlags;
}

GLContext::GLContext(const GLContextDesc& desc, GLContext* sharedContext,
                     bool useTLSIsCurrent)
    : mDesc(desc),
      mUseTLSIsCurrent(ShouldUseTLSIsCurrent(useTLSIsCurrent)),
      mDebugFlags(ChooseDebugFlags(mDesc.flags)),
      mSharedContext(sharedContext),
      mOwningThreadId(Some(PlatformThread::CurrentId())),
      mWorkAroundDriverBugs(
          StaticPrefs::gfx_work_around_driver_bugs_AtStartup()) {}

GLContext::~GLContext() {
  NS_ASSERTION(
      IsDestroyed(),
      "GLContext implementation must call MarkDestroyed in destructor!");
#ifdef MOZ_GL_DEBUG_BUILD
  if (mSharedContext) {
    GLContext* tip = mSharedContext;
    while (tip->mSharedContext) tip = tip->mSharedContext;
    tip->SharedContextDestroyed(this);
    tip->ReportOutstandingNames();
  } else {
    ReportOutstandingNames();
  }
#endif
  // Ensure we clear sCurrentContext if we were the last context set and avoid
  // the memory getting reused.
  if (sCurrentContext.init() && sCurrentContext.get() == this) {
    sCurrentContext.set(nullptr);
  }
}

/*static*/
void GLContext::InvalidateCurrentContext() {
  if (sCurrentContext.init()) {
    sCurrentContext.set(nullptr);
  }
}

/*static*/
void GLContext::StaticDebugCallback(GLenum source, GLenum type, GLuint id,
                                    GLenum severity, GLsizei length,
                                    const GLchar* message,
                                    const GLvoid* userParam) {
  GLContext* gl = (GLContext*)userParam;
  gl->DebugCallback(source, type, id, severity, length, message);
}

bool GLContext::Init() {
  MOZ_RELEASE_ASSERT(!mSymbols.fBindFramebuffer,
                     "GFX: GLContext::Init should only be called once.");

  ScopedGfxFeatureReporter reporter("GL Context");

  if (!InitImpl()) {
    // If initialization fails, zero the symbols to avoid hard-to-understand
    // bugs.
    mSymbols = {};
    NS_WARNING("GLContext::InitWithPrefix failed!");
    return false;
  }

  reporter.SetSuccessful();
  return true;
}

static bool LoadSymbolsWithDesc(const SymbolLoader& loader,
                                const SymLoadStruct* list, const char* desc) {
  const auto warnOnFailure = bool(desc);
  if (loader.LoadSymbols(list, warnOnFailure)) return true;

  ClearSymbols(list);

  if (desc) {
    const nsPrintfCString err("Failed to load symbols for %s.", desc);
    NS_ERROR(err.BeginReading());
  }
  return false;
}

bool GLContext::LoadExtSymbols(const SymbolLoader& loader,
                               const SymLoadStruct* list, GLExtensions ext) {
  const char* extName = sExtensionNames[size_t(ext)];
  if (!LoadSymbolsWithDesc(loader, list, extName)) {
    MarkExtensionUnsupported(ext);
    return false;
  }
  return true;
};

bool GLContext::LoadFeatureSymbols(const SymbolLoader& loader,
                                   const SymLoadStruct* list,
                                   GLFeature feature) {
  const char* featureName = GetFeatureName(feature);
  if (!LoadSymbolsWithDesc(loader, list, featureName)) {
    MarkUnsupported(feature);
    return false;
  }
  return true;
};

bool GLContext::InitImpl() {
  if (!MakeCurrent(true)) return false;

  const auto loader = GetSymbolLoader();
  if (!loader) return false;

  const auto fnLoadSymbols = [&](const SymLoadStruct* const list,
                                 const char* const desc) {
    return LoadSymbolsWithDesc(*loader, list, desc);
  };

  // clang-format off
    const SymLoadStruct coreSymbols[] = {
        { (PRFuncPtr*) &mSymbols.fActiveTexture, {{ "glActiveTexture", "glActiveTextureARB" }} },
        { (PRFuncPtr*) &mSymbols.fAttachShader, {{ "glAttachShader", "glAttachShaderARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindAttribLocation, {{ "glBindAttribLocation", "glBindAttribLocationARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindBuffer, {{ "glBindBuffer", "glBindBufferARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindTexture, {{ "glBindTexture", "glBindTextureARB" }} },
        { (PRFuncPtr*) &mSymbols.fBlendColor, {{ "glBlendColor" }} },
        { (PRFuncPtr*) &mSymbols.fBlendEquation, {{ "glBlendEquation" }} },
        { (PRFuncPtr*) &mSymbols.fBlendEquationSeparate, {{ "glBlendEquationSeparate", "glBlendEquationSeparateEXT" }} },
        { (PRFuncPtr*) &mSymbols.fBlendFunc, {{ "glBlendFunc" }} },
        { (PRFuncPtr*) &mSymbols.fBlendFuncSeparate, {{ "glBlendFuncSeparate", "glBlendFuncSeparateEXT" }} },
        { (PRFuncPtr*) &mSymbols.fBufferData, {{ "glBufferData" }} },
        { (PRFuncPtr*) &mSymbols.fBufferSubData, {{ "glBufferSubData" }} },
        { (PRFuncPtr*) &mSymbols.fClear, {{ "glClear" }} },
        { (PRFuncPtr*) &mSymbols.fClearColor, {{ "glClearColor" }} },
        { (PRFuncPtr*) &mSymbols.fClearStencil, {{ "glClearStencil" }} },
        { (PRFuncPtr*) &mSymbols.fColorMask, {{ "glColorMask" }} },
        { (PRFuncPtr*) &mSymbols.fCompressedTexImage2D, {{ "glCompressedTexImage2D" }} },
        { (PRFuncPtr*) &mSymbols.fCompressedTexSubImage2D, {{ "glCompressedTexSubImage2D" }} },
        { (PRFuncPtr*) &mSymbols.fCullFace, {{ "glCullFace" }} },
        { (PRFuncPtr*) &mSymbols.fDetachShader, {{ "glDetachShader", "glDetachShaderARB" }} },
        { (PRFuncPtr*) &mSymbols.fDepthFunc, {{ "glDepthFunc" }} },
        { (PRFuncPtr*) &mSymbols.fDepthMask, {{ "glDepthMask" }} },
        { (PRFuncPtr*) &mSymbols.fDisable, {{ "glDisable" }} },
        { (PRFuncPtr*) &mSymbols.fDisableVertexAttribArray, {{ "glDisableVertexAttribArray", "glDisableVertexAttribArrayARB" }} },
        { (PRFuncPtr*) &mSymbols.fDrawArrays, {{ "glDrawArrays" }} },
        { (PRFuncPtr*) &mSymbols.fDrawElements, {{ "glDrawElements" }} },
        { (PRFuncPtr*) &mSymbols.fEnable, {{ "glEnable" }} },
        { (PRFuncPtr*) &mSymbols.fEnableVertexAttribArray, {{ "glEnableVertexAttribArray", "glEnableVertexAttribArrayARB" }} },
        { (PRFuncPtr*) &mSymbols.fFinish, {{ "glFinish" }} },
        { (PRFuncPtr*) &mSymbols.fFlush, {{ "glFlush" }} },
        { (PRFuncPtr*) &mSymbols.fFrontFace, {{ "glFrontFace" }} },
        { (PRFuncPtr*) &mSymbols.fGetActiveAttrib, {{ "glGetActiveAttrib", "glGetActiveAttribARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetActiveUniform, {{ "glGetActiveUniform", "glGetActiveUniformARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetAttachedShaders, {{ "glGetAttachedShaders", "glGetAttachedShadersARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetAttribLocation, {{ "glGetAttribLocation", "glGetAttribLocationARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetIntegerv, {{ "glGetIntegerv" }} },
        { (PRFuncPtr*) &mSymbols.fGetFloatv, {{ "glGetFloatv" }} },
        { (PRFuncPtr*) &mSymbols.fGetBooleanv, {{ "glGetBooleanv" }} },
        { (PRFuncPtr*) &mSymbols.fGetBufferParameteriv, {{ "glGetBufferParameteriv", "glGetBufferParameterivARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetError, {{ "glGetError" }} },
        { (PRFuncPtr*) &mSymbols.fGetProgramiv, {{ "glGetProgramiv", "glGetProgramivARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetProgramInfoLog, {{ "glGetProgramInfoLog", "glGetProgramInfoLogARB" }} },
        { (PRFuncPtr*) &mSymbols.fTexParameteri, {{ "glTexParameteri" }} },
        { (PRFuncPtr*) &mSymbols.fTexParameteriv, {{ "glTexParameteriv" }} },
        { (PRFuncPtr*) &mSymbols.fTexParameterf, {{ "glTexParameterf" }} },
        { (PRFuncPtr*) &mSymbols.fGetString, {{ "glGetString" }} },
        { (PRFuncPtr*) &mSymbols.fGetTexParameterfv, {{ "glGetTexParameterfv" }} },
        { (PRFuncPtr*) &mSymbols.fGetTexParameteriv, {{ "glGetTexParameteriv" }} },
        { (PRFuncPtr*) &mSymbols.fGetUniformfv, {{ "glGetUniformfv", "glGetUniformfvARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetUniformiv, {{ "glGetUniformiv", "glGetUniformivARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetUniformLocation, {{ "glGetUniformLocation", "glGetUniformLocationARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetVertexAttribfv, {{ "glGetVertexAttribfv", "glGetVertexAttribfvARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetVertexAttribiv, {{ "glGetVertexAttribiv", "glGetVertexAttribivARB" }} },
        { (PRFuncPtr*) &mSymbols.fGetVertexAttribPointerv, {{ "glGetVertexAttribPointerv" }} },
        { (PRFuncPtr*) &mSymbols.fHint, {{ "glHint" }} },
        { (PRFuncPtr*) &mSymbols.fIsBuffer, {{ "glIsBuffer", "glIsBufferARB" }} },
        { (PRFuncPtr*) &mSymbols.fIsEnabled, {{ "glIsEnabled" }} },
        { (PRFuncPtr*) &mSymbols.fIsProgram, {{ "glIsProgram", "glIsProgramARB" }} },
        { (PRFuncPtr*) &mSymbols.fIsShader, {{ "glIsShader", "glIsShaderARB" }} },
        { (PRFuncPtr*) &mSymbols.fIsTexture, {{ "glIsTexture", "glIsTextureARB" }} },
        { (PRFuncPtr*) &mSymbols.fLineWidth, {{ "glLineWidth" }} },
        { (PRFuncPtr*) &mSymbols.fLinkProgram, {{ "glLinkProgram", "glLinkProgramARB" }} },
        { (PRFuncPtr*) &mSymbols.fPixelStorei, {{ "glPixelStorei" }} },
        { (PRFuncPtr*) &mSymbols.fPolygonOffset, {{ "glPolygonOffset" }} },
        { (PRFuncPtr*) &mSymbols.fReadPixels, {{ "glReadPixels" }} },
        { (PRFuncPtr*) &mSymbols.fSampleCoverage, {{ "glSampleCoverage" }} },
        { (PRFuncPtr*) &mSymbols.fScissor, {{ "glScissor" }} },
        { (PRFuncPtr*) &mSymbols.fStencilFunc, {{ "glStencilFunc" }} },
        { (PRFuncPtr*) &mSymbols.fStencilFuncSeparate, {{ "glStencilFuncSeparate", "glStencilFuncSeparateEXT" }} },
        { (PRFuncPtr*) &mSymbols.fStencilMask, {{ "glStencilMask" }} },
        { (PRFuncPtr*) &mSymbols.fStencilMaskSeparate, {{ "glStencilMaskSeparate", "glStencilMaskSeparateEXT" }} },
        { (PRFuncPtr*) &mSymbols.fStencilOp, {{ "glStencilOp" }} },
        { (PRFuncPtr*) &mSymbols.fStencilOpSeparate, {{ "glStencilOpSeparate", "glStencilOpSeparateEXT" }} },
        { (PRFuncPtr*) &mSymbols.fTexImage2D, {{ "glTexImage2D" }} },
        { (PRFuncPtr*) &mSymbols.fTexSubImage2D, {{ "glTexSubImage2D" }} },
        { (PRFuncPtr*) &mSymbols.fUniform1f, {{ "glUniform1f" }} },
        { (PRFuncPtr*) &mSymbols.fUniform1fv, {{ "glUniform1fv" }} },
        { (PRFuncPtr*) &mSymbols.fUniform1i, {{ "glUniform1i" }} },
        { (PRFuncPtr*) &mSymbols.fUniform1iv, {{ "glUniform1iv" }} },
        { (PRFuncPtr*) &mSymbols.fUniform2f, {{ "glUniform2f" }} },
        { (PRFuncPtr*) &mSymbols.fUniform2fv, {{ "glUniform2fv" }} },
        { (PRFuncPtr*) &mSymbols.fUniform2i, {{ "glUniform2i" }} },
        { (PRFuncPtr*) &mSymbols.fUniform2iv, {{ "glUniform2iv" }} },
        { (PRFuncPtr*) &mSymbols.fUniform3f, {{ "glUniform3f" }} },
        { (PRFuncPtr*) &mSymbols.fUniform3fv, {{ "glUniform3fv" }} },
        { (PRFuncPtr*) &mSymbols.fUniform3i, {{ "glUniform3i" }} },
        { (PRFuncPtr*) &mSymbols.fUniform3iv, {{ "glUniform3iv" }} },
        { (PRFuncPtr*) &mSymbols.fUniform4f, {{ "glUniform4f" }} },
        { (PRFuncPtr*) &mSymbols.fUniform4fv, {{ "glUniform4fv" }} },
        { (PRFuncPtr*) &mSymbols.fUniform4i, {{ "glUniform4i" }} },
        { (PRFuncPtr*) &mSymbols.fUniform4iv, {{ "glUniform4iv" }} },
        { (PRFuncPtr*) &mSymbols.fUniformMatrix2fv, {{ "glUniformMatrix2fv" }} },
        { (PRFuncPtr*) &mSymbols.fUniformMatrix3fv, {{ "glUniformMatrix3fv" }} },
        { (PRFuncPtr*) &mSymbols.fUniformMatrix4fv, {{ "glUniformMatrix4fv" }} },
        { (PRFuncPtr*) &mSymbols.fUseProgram, {{ "glUseProgram" }} },
        { (PRFuncPtr*) &mSymbols.fValidateProgram, {{ "glValidateProgram" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttribPointer, {{ "glVertexAttribPointer" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttrib1f, {{ "glVertexAttrib1f" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttrib2f, {{ "glVertexAttrib2f" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttrib3f, {{ "glVertexAttrib3f" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttrib4f, {{ "glVertexAttrib4f" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttrib1fv, {{ "glVertexAttrib1fv" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttrib2fv, {{ "glVertexAttrib2fv" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttrib3fv, {{ "glVertexAttrib3fv" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttrib4fv, {{ "glVertexAttrib4fv" }} },
        { (PRFuncPtr*) &mSymbols.fViewport, {{ "glViewport" }} },
        { (PRFuncPtr*) &mSymbols.fCompileShader, {{ "glCompileShader" }} },
        { (PRFuncPtr*) &mSymbols.fCopyTexImage2D, {{ "glCopyTexImage2D" }} },
        { (PRFuncPtr*) &mSymbols.fCopyTexSubImage2D, {{ "glCopyTexSubImage2D" }} },
        { (PRFuncPtr*) &mSymbols.fGetShaderiv, {{ "glGetShaderiv" }} },
        { (PRFuncPtr*) &mSymbols.fGetShaderInfoLog, {{ "glGetShaderInfoLog" }} },
        { (PRFuncPtr*) &mSymbols.fGetShaderSource, {{ "glGetShaderSource" }} },
        { (PRFuncPtr*) &mSymbols.fShaderSource, {{ "glShaderSource" }} },
        { (PRFuncPtr*) &mSymbols.fVertexAttribPointer, {{ "glVertexAttribPointer" }} },

        { (PRFuncPtr*) &mSymbols.fGenBuffers, {{ "glGenBuffers", "glGenBuffersARB" }} },
        { (PRFuncPtr*) &mSymbols.fGenTextures, {{ "glGenTextures" }} },
        { (PRFuncPtr*) &mSymbols.fCreateProgram, {{ "glCreateProgram", "glCreateProgramARB" }} },
        { (PRFuncPtr*) &mSymbols.fCreateShader, {{ "glCreateShader", "glCreateShaderARB" }} },

        { (PRFuncPtr*) &mSymbols.fDeleteBuffers, {{ "glDeleteBuffers", "glDeleteBuffersARB" }} },
        { (PRFuncPtr*) &mSymbols.fDeleteTextures, {{ "glDeleteTextures", "glDeleteTexturesARB" }} },
        { (PRFuncPtr*) &mSymbols.fDeleteProgram, {{ "glDeleteProgram", "glDeleteProgramARB" }} },
        { (PRFuncPtr*) &mSymbols.fDeleteShader, {{ "glDeleteShader", "glDeleteShaderARB" }} },

        END_SYMBOLS
    };
  // clang-format on

  if (!fnLoadSymbols(coreSymbols, "GL")) return false;

  {
    const SymLoadStruct symbols[] = {
        {(PRFuncPtr*)&mSymbols.fGetGraphicsResetStatus,
         {{"glGetGraphicsResetStatus", "glGetGraphicsResetStatusARB",
           "glGetGraphicsResetStatusKHR", "glGetGraphicsResetStatusEXT"}}},
        END_SYMBOLS};
    (void)fnLoadSymbols(symbols, nullptr);

    // We need to call the fGetError symbol directly here because if there is an
    // unflushed reset status, we don't want to mark the context as lost. That
    // would prevent us from recovering.
    auto err = mSymbols.fGetError();
    if (err == LOCAL_GL_CONTEXT_LOST) {
      MOZ_ASSERT(mSymbols.fGetGraphicsResetStatus);
      const auto status = fGetGraphicsResetStatus();
      if (status) {
        printf_stderr("Unflushed glGetGraphicsResetStatus: 0x%04x\n", status);
      }
      err = fGetError();
      MOZ_ASSERT(!err);
    }
    if (err) {
      MOZ_ASSERT(false);
      return false;
    }
  }

  ////////////////

  const auto* const versionRawStr = (const char*)fGetString(LOCAL_GL_VERSION);
  if (!versionRawStr || !*versionRawStr) {
    // This can happen with Pernosco.
    NS_WARNING("Empty GL version string");
    return false;
  }

  const std::string versionStr = versionRawStr;
  if (versionStr.find("OpenGL ES") == 0) {
    mProfile = ContextProfile::OpenGLES;
  }

  uint32_t majorVer, minorVer;
  if (!ParseVersion(versionStr, &majorVer, &minorVer)) {
    MOZ_ASSERT(false, "Failed to parse GL_VERSION");
    return false;
  }
  MOZ_ASSERT(majorVer < 10);
  MOZ_ASSERT(minorVer < 10);
  mVersion = majorVer * 100 + minorVer * 10;
  if (mVersion < 200) return false;

  ////

  const auto glslVersionStr =
      (const char*)fGetString(LOCAL_GL_SHADING_LANGUAGE_VERSION);
  if (!glslVersionStr) {
    // This happens on the Android emulators. We'll just return 100
    mShadingLanguageVersion = 100;
  } else if (ParseVersion(glslVersionStr, &majorVer, &minorVer)) {
    MOZ_ASSERT(majorVer < 10);
    MOZ_ASSERT(minorVer < 100);
    mShadingLanguageVersion = majorVer * 100 + minorVer;
  } else {
    MOZ_ASSERT(false, "Failed to parse GL_SHADING_LANGUAGE_VERSION");
    return false;
  }

  if (ShouldSpew()) {
    printf_stderr("GL version detected: %u\n", mVersion);
    printf_stderr("GLSL version detected: %u\n", mShadingLanguageVersion);
    printf_stderr("OpenGL vendor: %s\n", fGetString(LOCAL_GL_VENDOR));
    printf_stderr("OpenGL renderer: %s\n", fGetString(LOCAL_GL_RENDERER));
  }

  ////////////////

  // Load OpenGL ES 2.0 symbols, or desktop if we aren't using ES 2.
  if (mProfile == ContextProfile::OpenGLES) {
    const SymLoadStruct symbols[] = {CORE_SYMBOL(GetShaderPrecisionFormat),
                                     CORE_SYMBOL(ClearDepthf),
                                     CORE_SYMBOL(DepthRangef), END_SYMBOLS};

    if (!fnLoadSymbols(symbols, "OpenGL ES")) return false;
  } else {
    const SymLoadStruct symbols[] = {
        CORE_SYMBOL(ClearDepth), CORE_SYMBOL(DepthRange),
        CORE_SYMBOL(ReadBuffer), CORE_SYMBOL(MapBuffer),
        CORE_SYMBOL(UnmapBuffer), CORE_SYMBOL(PointParameterf),
        CORE_SYMBOL(DrawBuffer),
        // The following functions are only used by Skia/GL in desktop mode.
        // Other parts of Gecko should avoid using these
        CORE_SYMBOL(DrawBuffers), CORE_SYMBOL(ClientActiveTexture),
        CORE_SYMBOL(DisableClientState), CORE_SYMBOL(EnableClientState),
        CORE_SYMBOL(LoadIdentity), CORE_SYMBOL(LoadMatrixf),
        CORE_SYMBOL(MatrixMode), CORE_SYMBOL(PolygonMode), CORE_SYMBOL(TexGeni),
        CORE_SYMBOL(TexGenf), CORE_SYMBOL(TexGenfv), CORE_SYMBOL(VertexPointer),
        END_SYMBOLS};

    if (!fnLoadSymbols(symbols, "Desktop OpenGL")) return false;
  }

  ////////////////

  const char* glVendorString = (const char*)fGetString(LOCAL_GL_VENDOR);
  const char* glRendererString = (const char*)fGetString(LOCAL_GL_RENDERER);
  if (!glVendorString || !glRendererString) return false;

  // The order of these strings must match up with the order of the enum
  // defined in GLContext.h for vendor IDs.
  const char* vendorMatchStrings[size_t(GLVendor::Other) + 1] = {
      "Intel",   "NVIDIA",  "ATI",          "Qualcomm", "Imagination",
      "nouveau", "Vivante", "VMware, Inc.", "ARM",      "Unknown"};

  mVendor = GLVendor::Other;
  for (size_t i = 0; i < size_t(GLVendor::Other); ++i) {
    if (DoesStringMatch(glVendorString, vendorMatchStrings[i])) {
      mVendor = GLVendor(i);
      break;
    }
  }

  // The order of these strings must match up with the order of the enum
  // defined in GLContext.h for renderer IDs.
  const char* rendererMatchStrings[size_t(GLRenderer::Other) + 1] = {
      "Adreno 200",
      "Adreno 205",
      "Adreno (TM) 200",
      "Adreno (TM) 205",
      "Adreno (TM) 305",
      "Adreno (TM) 320",
      "Adreno (TM) 330",
      "Adreno (TM) 420",
      "Mali-400 MP",
      "Mali-450 MP",
      "Mali-T",
      "PowerVR SGX 530",
      "PowerVR SGX 540",
      "PowerVR SGX 544MP",
      "NVIDIA Tegra",
      "Android Emulator",
      "Gallium 0.4 on llvmpipe",
      "Intel HD Graphics 3000 OpenGL Engine",
      "Microsoft Basic Render Driver",
      "Samsung Xclipse",
      "Unknown"};

  mRenderer = GLRenderer::Other;
  for (size_t i = 0; i < size_t(GLRenderer::Other); ++i) {
    if (DoesStringMatch(glRendererString, rendererMatchStrings[i])) {
      mRenderer = GLRenderer(i);
      break;
    }
  }

  {
    const auto versionStr = (const char*)fGetString(LOCAL_GL_VERSION);
    if (strstr(versionStr, "Mesa")) {
      mIsMesa = true;
    }
  }

  const auto Once = []() {
    static bool did = false;
    if (did) return false;
    did = true;
    return true;
  };

  bool printRenderer = ShouldSpew();
  printRenderer |= (kIsDebug && Once());
  if (printRenderer) {
    printf_stderr("GL_VENDOR: %s\n", glVendorString);
    printf_stderr("mVendor: %s\n", vendorMatchStrings[size_t(mVendor)]);
    printf_stderr("GL_RENDERER: %s\n", glRendererString);
    printf_stderr("mRenderer: %s\n", rendererMatchStrings[size_t(mRenderer)]);
    printf_stderr("mIsMesa: %i\n", int(mIsMesa));
  }

  ////////////////

  if (mVersion >= 300) {  // Both GL3 and ES3.
    const SymLoadStruct symbols[] = {
        {(PRFuncPtr*)&mSymbols.fGetStringi, {{"glGetStringi"}}}, END_SYMBOLS};

    if (!fnLoadSymbols(symbols, "GetStringi")) {
      MOZ_RELEASE_ASSERT(false, "GFX: GetStringi is required!");
      return false;
    }
  }

  InitExtensions();
  if (mProfile != ContextProfile::OpenGLES) {
    if (mVersion >= 310 && !IsExtensionSupported(ARB_compatibility)) {
      mProfile = ContextProfile::OpenGLCore;
    } else {
      mProfile = ContextProfile::OpenGLCompatibility;
    }
  }
  MOZ_ASSERT(mProfile != ContextProfile::Unknown);

  if (ShouldSpew()) {
    const char* profileStr = "";
    if (mProfile == ContextProfile::OpenGLES) {
      profileStr = " es";
    } else if (mProfile == ContextProfile::OpenGLCore) {
      profileStr = " core";
    }
    printf_stderr("Detected profile: %u%s\n", mVersion, profileStr);
  }

  InitFeatures();

  ////

  // Disable extensions with partial or incorrect support.
  if (WorkAroundDriverBugs()) {
    if (Renderer() == GLRenderer::AdrenoTM320) {
      MarkUnsupported(GLFeature::standard_derivatives);
    }

    if (Renderer() == GLRenderer::AndroidEmulator) {
      // Bug 1665300
      mSymbols.fGetGraphicsResetStatus = 0;
    }

    if (Vendor() == GLVendor::Vivante) {
      // bug 958256
      MarkUnsupported(GLFeature::standard_derivatives);
    }

    if (Renderer() == GLRenderer::MicrosoftBasicRenderDriver) {
      // Bug 978966: on Microsoft's "Basic Render Driver" (software renderer)
      // multisampling hardcodes blending with the default blendfunc, which
      // breaks WebGL.
      MarkUnsupported(GLFeature::framebuffer_multisample);
    }

    if (IsMesa()) {
      // DrawElementsInstanced hangs the driver.
      MarkUnsupported(GLFeature::robust_buffer_access_behavior);
    }

    if (Renderer() == GLRenderer::SamsungXclipse) {
      MarkUnsupported(GLFeature::invalidate_framebuffer);
    }
  }

  if (IsExtensionSupported(GLContext::ARB_pixel_buffer_object)) {
    MOZ_ASSERT(
        (mSymbols.fMapBuffer && mSymbols.fUnmapBuffer),
        "ARB_pixel_buffer_object supported without glMapBuffer/UnmapBuffer"
        " being available!");
  }

  ////////////////////////////////////////////////////////////////////////////

  const auto fnLoadForFeature = [&](const SymLoadStruct* list,
                                    GLFeature feature) {
    return this->LoadFeatureSymbols(*loader, list, feature);
  };

  // Check for ARB_framebuffer_objects
  if (IsSupported(GLFeature::framebuffer_object)) {
    // https://www.opengl.org/registry/specs/ARB/framebuffer_object.txt
    const SymLoadStruct symbols[] = {
        CORE_SYMBOL(IsRenderbuffer),
        CORE_SYMBOL(BindRenderbuffer),
        CORE_SYMBOL(DeleteRenderbuffers),
        CORE_SYMBOL(GenRenderbuffers),
        CORE_SYMBOL(RenderbufferStorage),
        CORE_SYMBOL(RenderbufferStorageMultisample),
        CORE_SYMBOL(GetRenderbufferParameteriv),
        CORE_SYMBOL(IsFramebuffer),
        CORE_SYMBOL(BindFramebuffer),
        CORE_SYMBOL(DeleteFramebuffers),
        CORE_SYMBOL(GenFramebuffers),
        CORE_SYMBOL(CheckFramebufferStatus),
        CORE_SYMBOL(FramebufferTexture2D),
        CORE_SYMBOL(FramebufferTextureLayer),
        CORE_SYMBOL(FramebufferRenderbuffer),
        CORE_SYMBOL(GetFramebufferAttachmentParameteriv),
        CORE_SYMBOL(BlitFramebuffer),
        CORE_SYMBOL(GenerateMipmap),
        END_SYMBOLS};
    fnLoadForFeature(symbols, GLFeature::framebuffer_object);
  }

  if (!IsSupported(GLFeature::framebuffer_object)) {
    // Check for aux symbols based on extensions
    if (IsSupported(GLFeature::framebuffer_object_EXT_OES)) {
      const SymLoadStruct symbols[] = {
          CORE_EXT_SYMBOL2(IsRenderbuffer, EXT, OES),
          CORE_EXT_SYMBOL2(BindRenderbuffer, EXT, OES),
          CORE_EXT_SYMBOL2(DeleteRenderbuffers, EXT, OES),
          CORE_EXT_SYMBOL2(GenRenderbuffers, EXT, OES),
          CORE_EXT_SYMBOL2(RenderbufferStorage, EXT, OES),
          CORE_EXT_SYMBOL2(GetRenderbufferParameteriv, EXT, OES),
          CORE_EXT_SYMBOL2(IsFramebuffer, EXT, OES),
          CORE_EXT_SYMBOL2(BindFramebuffer, EXT, OES),
          CORE_EXT_SYMBOL2(DeleteFramebuffers, EXT, OES),
          CORE_EXT_SYMBOL2(GenFramebuffers, EXT, OES),
          CORE_EXT_SYMBOL2(CheckFramebufferStatus, EXT, OES),
          CORE_EXT_SYMBOL2(FramebufferTexture2D, EXT, OES),
          CORE_EXT_SYMBOL2(FramebufferRenderbuffer, EXT, OES),
          CORE_EXT_SYMBOL2(GetFramebufferAttachmentParameteriv, EXT, OES),
          CORE_EXT_SYMBOL2(GenerateMipmap, EXT, OES),
          END_SYMBOLS};
      fnLoadForFeature(symbols, GLFeature::framebuffer_object_EXT_OES);
    }

    if (IsSupported(GLFeature::framebuffer_blit)) {
      const SymLoadStruct symbols[] = {
          EXT_SYMBOL3(BlitFramebuffer, ANGLE, EXT, NV), END_SYMBOLS};
      fnLoadForFeature(symbols, GLFeature::framebuffer_blit);
    }

    if (IsSupported(GLFeature::framebuffer_multisample)) {
      const SymLoadStruct symbols[] = {
          EXT_SYMBOL3(RenderbufferStorageMultisample, ANGLE, APPLE, EXT),
          END_SYMBOLS};
      fnLoadForFeature(symbols, GLFeature::framebuffer_multisample);
    }

    if (IsExtensionSupported(GLContext::ARB_geometry_shader4) ||
        IsExtensionSupported(GLContext::NV_geometry_program4)) {
      const SymLoadStruct symbols[] = {
          EXT_SYMBOL2(FramebufferTextureLayer, ARB, EXT), END_SYMBOLS};
      if (!fnLoadSymbols(symbols,
                         "ARB_geometry_shader4/NV_geometry_program4")) {
        MarkExtensionUnsupported(GLContext::ARB_geometry_shader4);
        MarkExtensionUnsupported(GLContext::NV_geometry_program4);
      }
    }
  }

  if (!IsSupported(GLFeature::framebuffer_object) &&
      !IsSupported(GLFeature::framebuffer_object_EXT_OES)) {
    NS_ERROR("GLContext requires support for framebuffer objects.");
    return false;
  }
  MOZ_RELEASE_ASSERT(mSymbols.fBindFramebuffer,
                     "GFX: mSymbols.fBindFramebuffer zero or not set.");

  ////////////////

  const auto err = fGetError();
  MOZ_RELEASE_ASSERT(!IsBadCallError(err));
  if (err) return false;

  LoadMoreSymbols(*loader);

  ////////////////////////////////////////////////////////////////////////////

  raw_fGetIntegerv(LOCAL_GL_VIEWPORT, mViewportRect);
  raw_fGetIntegerv(LOCAL_GL_SCISSOR_BOX, mScissorRect);
  raw_fGetIntegerv(LOCAL_GL_MAX_TEXTURE_SIZE, &mMaxTextureSize);
  raw_fGetIntegerv(LOCAL_GL_MAX_CUBE_MAP_TEXTURE_SIZE, &mMaxCubeMapTextureSize);
  raw_fGetIntegerv(LOCAL_GL_MAX_RENDERBUFFER_SIZE, &mMaxRenderbufferSize);
  raw_fGetIntegerv(LOCAL_GL_MAX_VIEWPORT_DIMS, mMaxViewportDims);

  if (mWorkAroundDriverBugs) {
    int maxTexSize = INT32_MAX;
    int maxCubeSize = INT32_MAX;
#ifdef XP_MACOSX
    // https://bugzilla.mozilla.org/show_bug.cgi?id=1544446
    // Mojave exposes 16k textures, but gives FRAMEBUFFER_UNSUPPORTED for any
    // 16k*16k FB except rgba8 without depth/stencil.
    // The max supported sizes changes based on involved formats.
    // (RGBA32F more restrictive than RGBA16F)
    maxTexSize = 8192;
#endif
#ifdef MOZ_X11
    if (mVendor == GLVendor::Nouveau) {
      // see bug 814716. Clamp MaxCubeMapTextureSize at 2K for Nouveau.
      maxCubeSize = 2048;
    } else if (mVendor == GLVendor::Intel) {
      // Bug 1199923. Driver seems to report a larger max size than
      // actually supported.
      maxTexSize = mMaxTextureSize / 2;
    }
    // Bug 1367570. Explicitly set vertex attributes [1,3] to opaque
    // black because Nvidia doesn't do it for us.
    if (mVendor == GLVendor::NVIDIA) {
      for (size_t i = 1; i <= 3; ++i) {
        mSymbols.fVertexAttrib4f(i, 0, 0, 0, 1);
      }
    }
#endif
    if (Renderer() == GLRenderer::AdrenoTM420) {
      // see bug 1194923. Calling glFlush before glDeleteFramebuffers
      // prevents occasional driver crash.
      mNeedsFlushBeforeDeleteFB = true;
    }

    // -

    const auto fnLimit = [&](int* const driver, const int limit) {
      if (*driver > limit) {
        *driver = limit;
        mNeedsTextureSizeChecks = true;
      }
    };

    fnLimit(&mMaxTextureSize, maxTexSize);
    fnLimit(&mMaxRenderbufferSize, maxTexSize);

    maxCubeSize = std::min(maxCubeSize, maxTexSize);
    fnLimit(&mMaxCubeMapTextureSize, maxCubeSize);
  }

  if (IsSupported(GLFeature::framebuffer_multisample)) {
    fGetIntegerv(LOCAL_GL_MAX_SAMPLES, (GLint*)&mMaxSamples);
  }

  mMaxTexOrRbSize = std::min(mMaxTextureSize, mMaxRenderbufferSize);

  ////////////////////////////////////////////////////////////////////////////

  // We're ready for final setup.
  fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, 0);
  MOZ_GL_ASSERT(this, IsCurrent());

  if (ShouldSpew() && IsExtensionSupported(KHR_debug)) {
    fEnable(LOCAL_GL_DEBUG_OUTPUT);
    fDisable(LOCAL_GL_DEBUG_OUTPUT_SYNCHRONOUS);
    fDebugMessageCallback(&StaticDebugCallback, (void*)this);
    fDebugMessageControl(LOCAL_GL_DONT_CARE, LOCAL_GL_DONT_CARE,
                         LOCAL_GL_DONT_CARE, 0, nullptr, true);
  }

  return true;
}

void GLContext::LoadMoreSymbols(const SymbolLoader& loader) {
  const auto fnLoadForExt = [&](const SymLoadStruct* list, GLExtensions ext) {
    return this->LoadExtSymbols(loader, list, ext);
  };

  const auto fnLoadForFeature = [&](const SymLoadStruct* list,
                                    GLFeature feature) {
    return this->LoadFeatureSymbols(loader, list, feature);
  };

  const auto fnLoadFeatureByCore = [&](const SymLoadStruct* coreList,
                                       const SymLoadStruct* extList,
                                       GLFeature feature) {
    const bool useCore = this->IsFeatureProvidedByCoreSymbols(feature);
    const auto list = useCore ? coreList : extList;
    return fnLoadForFeature(list, feature);
  };

  if (IsSupported(GLFeature::robustness)) {
    const auto resetStrategy =
        GetIntAs<GLuint>(LOCAL_GL_RESET_NOTIFICATION_STRATEGY);
    if (resetStrategy != LOCAL_GL_LOSE_CONTEXT_ON_RESET) {
      NS_WARNING(
          "Robustness supported, strategy is not LOSE_CONTEXT_ON_RESET!");
      if (ShouldSpew()) {
        const bool isDisabled =
            (resetStrategy == LOCAL_GL_NO_RESET_NOTIFICATION);
        printf_stderr("Strategy: %s (0x%04x)",
                      (isDisabled ? "disabled" : "unrecognized"),
                      resetStrategy);
      }
      MarkUnsupported(GLFeature::robustness);
    }
  }

  if (IsSupported(GLFeature::sync)) {
    const SymLoadStruct symbols[] = {
        CORE_SYMBOL(FenceSync),  CORE_SYMBOL(IsSync),
        CORE_SYMBOL(DeleteSync), CORE_SYMBOL(ClientWaitSync),
        CORE_SYMBOL(WaitSync),   CORE_SYMBOL(GetInteger64v),
        CORE_SYMBOL(GetSynciv),  END_SYMBOLS};
    fnLoadForFeature(symbols, GLFeature::sync);
  }

  if (IsExtensionSupported(OES_EGL_image)) {
    const SymLoadStruct symbols[] = {
        {(PRFuncPtr*)&mSymbols.fEGLImageTargetTexture2D,
         {{"glEGLImageTargetTexture2DOES"}}},
        {(PRFuncPtr*)&mSymbols.fEGLImageTargetRenderbufferStorage,
         {{"glEGLImageTargetRenderbufferStorageOES"}}},
        END_SYMBOLS};
    fnLoadForExt(symbols, OES_EGL_image);
  }

  if (IsExtensionSupported(APPLE_texture_range)) {
    const SymLoadStruct symbols[] = {CORE_SYMBOL(TextureRangeAPPLE),
                                     END_SYMBOLS};
    fnLoadForExt(symbols, APPLE_texture_range);
  }

  if (IsExtensionSupported(APPLE_fence)) {
    const SymLoadStruct symbols[] = {CORE_SYMBOL(FinishObjectAPPLE),
                                     CORE_SYMBOL(TestObjectAPPLE), END_SYMBOLS};
    fnLoadForExt(symbols, APPLE_fence);
  }

  // clang-format off

    if (IsSupported(GLFeature::vertex_array_object)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fIsVertexArray, {{ "glIsVertexArray" }} },
            { (PRFuncPtr*) &mSymbols.fGenVertexArrays, {{ "glGenVertexArrays" }} },
            { (PRFuncPtr*) &mSymbols.fBindVertexArray, {{ "glBindVertexArray" }} },
            { (PRFuncPtr*) &mSymbols.fDeleteVertexArrays, {{ "glDeleteVertexArrays" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fIsVertexArray, {{ "glIsVertexArrayARB", "glIsVertexArrayOES", "glIsVertexArrayAPPLE" }} },
            { (PRFuncPtr*) &mSymbols.fGenVertexArrays, {{ "glGenVertexArraysARB", "glGenVertexArraysOES", "glGenVertexArraysAPPLE" }} },
            { (PRFuncPtr*) &mSymbols.fBindVertexArray, {{ "glBindVertexArrayARB", "glBindVertexArrayOES", "glBindVertexArrayAPPLE" }} },
            { (PRFuncPtr*) &mSymbols.fDeleteVertexArrays, {{ "glDeleteVertexArraysARB", "glDeleteVertexArraysOES", "glDeleteVertexArraysAPPLE" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::vertex_array_object);
    }

    if (IsSupported(GLFeature::draw_instanced)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fDrawArraysInstanced, {{ "glDrawArraysInstanced" }} },
            { (PRFuncPtr*) &mSymbols.fDrawElementsInstanced, {{ "glDrawElementsInstanced" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fDrawArraysInstanced, {{ "glDrawArraysInstancedARB", "glDrawArraysInstancedEXT", "glDrawArraysInstancedNV", "glDrawArraysInstancedANGLE" }} },
            { (PRFuncPtr*) &mSymbols.fDrawElementsInstanced, {{ "glDrawElementsInstancedARB", "glDrawElementsInstancedEXT", "glDrawElementsInstancedNV", "glDrawElementsInstancedANGLE" }}
            },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::draw_instanced);
    }

    if (IsSupported(GLFeature::instanced_arrays)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fVertexAttribDivisor, {{ "glVertexAttribDivisor" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fVertexAttribDivisor, {{ "glVertexAttribDivisorARB", "glVertexAttribDivisorNV", "glVertexAttribDivisorANGLE" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::instanced_arrays);
    }

    if (IsSupported(GLFeature::texture_storage)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fTexStorage2D, {{ "glTexStorage2D" }} },
            { (PRFuncPtr*) &mSymbols.fTexStorage3D, {{ "glTexStorage3D" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fTexStorage2D, {{ "glTexStorage2DEXT" }} },
            { (PRFuncPtr*) &mSymbols.fTexStorage3D, {{ "glTexStorage3DEXT" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::texture_storage);
    }

    if (IsSupported(GLFeature::sampler_objects)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fGenSamplers, {{ "glGenSamplers" }} },
            { (PRFuncPtr*) &mSymbols.fDeleteSamplers, {{ "glDeleteSamplers" }} },
            { (PRFuncPtr*) &mSymbols.fIsSampler, {{ "glIsSampler" }} },
            { (PRFuncPtr*) &mSymbols.fBindSampler, {{ "glBindSampler" }} },
            { (PRFuncPtr*) &mSymbols.fSamplerParameteri, {{ "glSamplerParameteri" }} },
            { (PRFuncPtr*) &mSymbols.fSamplerParameteriv, {{ "glSamplerParameteriv" }} },
            { (PRFuncPtr*) &mSymbols.fSamplerParameterf, {{ "glSamplerParameterf" }} },
            { (PRFuncPtr*) &mSymbols.fSamplerParameterfv, {{ "glSamplerParameterfv" }} },
            { (PRFuncPtr*) &mSymbols.fGetSamplerParameteriv, {{ "glGetSamplerParameteriv" }} },
            { (PRFuncPtr*) &mSymbols.fGetSamplerParameterfv, {{ "glGetSamplerParameterfv" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::sampler_objects);
    }

    // ARB_transform_feedback2/NV_transform_feedback2 is a
    // superset of EXT_transform_feedback/NV_transform_feedback
    // and adds glPauseTransformFeedback &
    // glResumeTransformFeedback, which are required for WebGL2.
    if (IsSupported(GLFeature::transform_feedback2)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fBindBufferBase, {{ "glBindBufferBase" }} },
            { (PRFuncPtr*) &mSymbols.fBindBufferRange, {{ "glBindBufferRange" }} },
            { (PRFuncPtr*) &mSymbols.fGenTransformFeedbacks, {{ "glGenTransformFeedbacks" }} },
            { (PRFuncPtr*) &mSymbols.fBindTransformFeedback, {{ "glBindTransformFeedback" }} },
            { (PRFuncPtr*) &mSymbols.fDeleteTransformFeedbacks, {{ "glDeleteTransformFeedbacks" }} },
            { (PRFuncPtr*) &mSymbols.fIsTransformFeedback, {{ "glIsTransformFeedback" }} },
            { (PRFuncPtr*) &mSymbols.fBeginTransformFeedback, {{ "glBeginTransformFeedback" }} },
            { (PRFuncPtr*) &mSymbols.fEndTransformFeedback, {{ "glEndTransformFeedback" }} },
            { (PRFuncPtr*) &mSymbols.fTransformFeedbackVaryings, {{ "glTransformFeedbackVaryings" }} },
            { (PRFuncPtr*) &mSymbols.fGetTransformFeedbackVarying, {{ "glGetTransformFeedbackVarying" }} },
            { (PRFuncPtr*) &mSymbols.fPauseTransformFeedback, {{ "glPauseTransformFeedback" }} },
            { (PRFuncPtr*) &mSymbols.fResumeTransformFeedback, {{ "glResumeTransformFeedback" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fBindBufferBase, {{ "glBindBufferBaseEXT", "glBindBufferBaseNV" }} },
            { (PRFuncPtr*) &mSymbols.fBindBufferRange, {{ "glBindBufferRangeEXT", "glBindBufferRangeNV" }} },
            { (PRFuncPtr*) &mSymbols.fGenTransformFeedbacks, {{ "glGenTransformFeedbacksNV" }} },
            { (PRFuncPtr*) &mSymbols.fBindTransformFeedback, {{ "glBindTransformFeedbackNV" }} },
            { (PRFuncPtr*) &mSymbols.fDeleteTransformFeedbacks, {{ "glDeleteTransformFeedbacksNV" }} },
            { (PRFuncPtr*) &mSymbols.fIsTransformFeedback, {{ "glIsTransformFeedbackNV" }} },
            { (PRFuncPtr*) &mSymbols.fBeginTransformFeedback, {{ "glBeginTransformFeedbackEXT", "glBeginTransformFeedbackNV" }} },
            { (PRFuncPtr*) &mSymbols.fEndTransformFeedback, {{ "glEndTransformFeedbackEXT", "glEndTransformFeedbackNV" }} },
            { (PRFuncPtr*) &mSymbols.fTransformFeedbackVaryings, {{ "glTransformFeedbackVaryingsEXT", "glTransformFeedbackVaryingsNV" }} },
            { (PRFuncPtr*) &mSymbols.fGetTransformFeedbackVarying, {{ "glGetTransformFeedbackVaryingEXT", "glGetTransformFeedbackVaryingNV" }} },
            { (PRFuncPtr*) &mSymbols.fPauseTransformFeedback, {{ "glPauseTransformFeedbackNV" }} },
            { (PRFuncPtr*) &mSymbols.fResumeTransformFeedback, {{ "glResumeTransformFeedbackNV" }} },
            END_SYMBOLS
        };
        if (!fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::transform_feedback2)) {
            // Also mark bind_buffer_offset as unsupported.
            MarkUnsupported(GLFeature::bind_buffer_offset);
        }
    }

    if (IsSupported(GLFeature::bind_buffer_offset)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fBindBufferOffset, {{ "glBindBufferOffset" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fBindBufferOffset,
              {{ "glBindBufferOffsetEXT", "glBindBufferOffsetNV" }}
            },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::bind_buffer_offset);
    }

    if (IsSupported(GLFeature::query_counter)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fQueryCounter, {{ "glQueryCounter" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fQueryCounter, {{ "glQueryCounterEXT", "glQueryCounterANGLE" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::query_counter);
    }

    if (IsSupported(GLFeature::query_objects)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fBeginQuery, {{ "glBeginQuery" }} },
            { (PRFuncPtr*) &mSymbols.fGenQueries, {{ "glGenQueries" }} },
            { (PRFuncPtr*) &mSymbols.fDeleteQueries, {{ "glDeleteQueries" }} },
            { (PRFuncPtr*) &mSymbols.fEndQuery, {{ "glEndQuery" }} },
            { (PRFuncPtr*) &mSymbols.fGetQueryiv, {{ "glGetQueryiv" }} },
            { (PRFuncPtr*) &mSymbols.fGetQueryObjectuiv, {{ "glGetQueryObjectuiv" }} },
            { (PRFuncPtr*) &mSymbols.fIsQuery, {{ "glIsQuery" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fBeginQuery, {{ "glBeginQueryEXT", "glBeginQueryANGLE" }} },
            { (PRFuncPtr*) &mSymbols.fGenQueries, {{ "glGenQueriesEXT", "glGenQueriesANGLE" }} },
            { (PRFuncPtr*) &mSymbols.fDeleteQueries, {{ "glDeleteQueriesEXT", "glDeleteQueriesANGLE" }} },
            { (PRFuncPtr*) &mSymbols.fEndQuery, {{ "glEndQueryEXT", "glEndQueryANGLE" }} },
            { (PRFuncPtr*) &mSymbols.fGetQueryiv, {{ "glGetQueryivEXT", "glGetQueryivANGLE" }} },
            { (PRFuncPtr*) &mSymbols.fGetQueryObjectuiv, {{ "glGetQueryObjectuivEXT", "glGetQueryObjectuivANGLE" }} },
            { (PRFuncPtr*) &mSymbols.fIsQuery, {{ "glIsQueryEXT", "glIsQueryANGLE" }} },
            END_SYMBOLS
        };
        if (!fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::query_objects)) {
            MarkUnsupported(GLFeature::get_query_object_i64v);
            MarkUnsupported(GLFeature::get_query_object_iv);
            MarkUnsupported(GLFeature::occlusion_query);
            MarkUnsupported(GLFeature::occlusion_query_boolean);
            MarkUnsupported(GLFeature::occlusion_query2);
        }
    }

    if (IsSupported(GLFeature::get_query_object_i64v)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fGetQueryObjecti64v, {{ "glGetQueryObjecti64v" }} },
            { (PRFuncPtr*) &mSymbols.fGetQueryObjectui64v, {{ "glGetQueryObjectui64v" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fGetQueryObjecti64v, {{ "glGetQueryObjecti64vEXT", "glGetQueryObjecti64vANGLE" }} },
            { (PRFuncPtr*) &mSymbols.fGetQueryObjectui64v, {{ "glGetQueryObjectui64vEXT", "glGetQueryObjectui64vANGLE" }} },
            END_SYMBOLS
        };
        if (!fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::get_query_object_i64v)) {
            MarkUnsupported(GLFeature::query_counter);
        }
    }

    if (IsSupported(GLFeature::get_query_object_iv)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fGetQueryObjectiv, {{ "glGetQueryObjectiv" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fGetQueryObjectiv, {{ "glGetQueryObjectivEXT", "glGetQueryObjectivANGLE" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::get_query_object_iv);
    }

    if (IsSupported(GLFeature::clear_buffers)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fClearBufferfi,  {{ "glClearBufferfi",  }} },
            { (PRFuncPtr*) &mSymbols.fClearBufferfv,  {{ "glClearBufferfv",  }} },
            { (PRFuncPtr*) &mSymbols.fClearBufferiv,  {{ "glClearBufferiv",  }} },
            { (PRFuncPtr*) &mSymbols.fClearBufferuiv, {{ "glClearBufferuiv" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::clear_buffers);
    }

    if (IsSupported(GLFeature::copy_buffer)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fCopyBufferSubData, {{ "glCopyBufferSubData" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::copy_buffer);
    }

    if (IsSupported(GLFeature::draw_buffers)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fDrawBuffers, {{ "glDrawBuffers" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fDrawBuffers, {{ "glDrawBuffersARB", "glDrawBuffersEXT" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::draw_buffers);
    }

    if (IsSupported(GLFeature::draw_buffers_indexed)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fBlendEquationSeparatei, {{ "glBlendEquationSeparatei" }} },
            { (PRFuncPtr*) &mSymbols.fBlendFuncSeparatei, {{ "glBlendFuncSeparatei" }} },
            { (PRFuncPtr*) &mSymbols.fColorMaski, {{ "glColorMaski" }} },
            { (PRFuncPtr*) &mSymbols.fDisablei, {{ "glDisablei" }} },
            { (PRFuncPtr*) &mSymbols.fEnablei, {{ "glEnablei" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fBlendEquationSeparatei, {{ "glBlendEquationSeparateiOES" }} },
            { (PRFuncPtr*) &mSymbols.fBlendFuncSeparatei, {{ "glBlendFuncSeparateiOES" }} },
            { (PRFuncPtr*) &mSymbols.fColorMaski, {{ "glColorMaskiOES" }} },
            { (PRFuncPtr*) &mSymbols.fDisablei, {{ "glDisableiOES" }} },
            { (PRFuncPtr*) &mSymbols.fEnablei, {{ "glEnableiOES" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::draw_buffers_indexed);
    }

    if (IsSupported(GLFeature::get_integer_indexed)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fGetIntegeri_v, {{ "glGetIntegeri_v" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] ={
            { (PRFuncPtr*) &mSymbols.fGetIntegeri_v, {{ "glGetIntegerIndexedvEXT" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::get_integer_indexed);
    }

    if (IsSupported(GLFeature::get_integer64_indexed)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fGetInteger64i_v, {{ "glGetInteger64i_v" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::get_integer64_indexed);
    }

    if (IsSupported(GLFeature::gpu_shader4)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fGetVertexAttribIiv, {{ "glGetVertexAttribIiv", "glGetVertexAttribIivEXT" }} },
            { (PRFuncPtr*) &mSymbols.fGetVertexAttribIuiv, {{ "glGetVertexAttribIuiv", "glGetVertexAttribIuivEXT" }} },
            { (PRFuncPtr*) &mSymbols.fVertexAttribI4i, {{ "glVertexAttribI4i", "glVertexAttribI4iEXT" }} },
            { (PRFuncPtr*) &mSymbols.fVertexAttribI4iv, {{ "glVertexAttribI4iv", "glVertexAttribI4ivEXT" }} },
            { (PRFuncPtr*) &mSymbols.fVertexAttribI4ui, {{ "glVertexAttribI4ui", "glVertexAttribI4uiEXT" }} },
            { (PRFuncPtr*) &mSymbols.fVertexAttribI4uiv, {{ "glVertexAttribI4uiv", "glVertexAttribI4uivEXT" }} },
            { (PRFuncPtr*) &mSymbols.fVertexAttribIPointer, {{ "glVertexAttribIPointer", "glVertexAttribIPointerEXT" }} },
            { (PRFuncPtr*) &mSymbols.fUniform1ui,  {{ "glUniform1ui", "glUniform1uiEXT" }} },
            { (PRFuncPtr*) &mSymbols.fUniform2ui,  {{ "glUniform2ui", "glUniform2uiEXT" }} },
            { (PRFuncPtr*) &mSymbols.fUniform3ui,  {{ "glUniform3ui", "glUniform3uiEXT" }} },
            { (PRFuncPtr*) &mSymbols.fUniform4ui,  {{ "glUniform4ui", "glUniform4uiEXT" }} },
            { (PRFuncPtr*) &mSymbols.fUniform1uiv, {{ "glUniform1uiv", "glUniform1uivEXT" }} },
            { (PRFuncPtr*) &mSymbols.fUniform2uiv, {{ "glUniform2uiv", "glUniform2uivEXT" }} },
            { (PRFuncPtr*) &mSymbols.fUniform3uiv, {{ "glUniform3uiv", "glUniform3uivEXT" }} },
            { (PRFuncPtr*) &mSymbols.fUniform4uiv, {{ "glUniform4uiv", "glUniform4uivEXT" }} },
            { (PRFuncPtr*) &mSymbols.fGetFragDataLocation, {{ "glGetFragDataLocation", "glGetFragDataLocationEXT" }} },
            { (PRFuncPtr*) &mSymbols.fGetUniformuiv, {{ "glGetUniformuiv", "glGetUniformuivEXT" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::gpu_shader4);
    }

    if (IsSupported(GLFeature::map_buffer_range)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fMapBufferRange, {{ "glMapBufferRange" }} },
            { (PRFuncPtr*) &mSymbols.fFlushMappedBufferRange, {{ "glFlushMappedBufferRange" }} },
            { (PRFuncPtr*) &mSymbols.fUnmapBuffer, {{ "glUnmapBuffer" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::map_buffer_range);
    }

    if (IsSupported(GLFeature::texture_3D)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fTexImage3D, {{ "glTexImage3D" }} },
            { (PRFuncPtr*) &mSymbols.fTexSubImage3D, {{ "glTexSubImage3D" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fTexImage3D, {{ "glTexImage3DOES" }} },
            { (PRFuncPtr*) &mSymbols.fTexSubImage3D, {{ "glTexSubImage3DOES" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::texture_3D);
    }

    if (IsSupported(GLFeature::texture_3D_compressed)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fCompressedTexImage3D, {{ "glCompressedTexImage3D" }} },
            { (PRFuncPtr*) &mSymbols.fCompressedTexSubImage3D, {{ "glCompressedTexSubImage3D" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fCompressedTexImage3D, {{ "glCompressedTexImage3DARB", "glCompressedTexImage3DOES" }} },
            { (PRFuncPtr*) &mSymbols.fCompressedTexSubImage3D, {{ "glCompressedTexSubImage3DARB", "glCompressedTexSubImage3DOES" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::texture_3D_compressed);
    }

    if (IsSupported(GLFeature::texture_3D_copy)) {
        const SymLoadStruct coreSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fCopyTexSubImage3D, {{ "glCopyTexSubImage3D" }} },
            END_SYMBOLS
        };
        const SymLoadStruct extSymbols[] = {
            { (PRFuncPtr*) &mSymbols.fCopyTexSubImage3D, {{ "glCopyTexSubImage3DEXT", "glCopyTexSubImage3DOES" }} },
            END_SYMBOLS
        };
        fnLoadFeatureByCore(coreSymbols, extSymbols, GLFeature::texture_3D_copy);
    }

    if (IsSupported(GLFeature::uniform_buffer_object)) {
        // Note: Don't query for glGetActiveUniformName because it is not
        // supported by GL ES 3.
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fGetUniformIndices, {{ "glGetUniformIndices" }} },
            { (PRFuncPtr*) &mSymbols.fGetActiveUniformsiv, {{ "glGetActiveUniformsiv" }} },
            { (PRFuncPtr*) &mSymbols.fGetUniformBlockIndex, {{ "glGetUniformBlockIndex" }} },
            { (PRFuncPtr*) &mSymbols.fGetActiveUniformBlockiv, {{ "glGetActiveUniformBlockiv" }} },
            { (PRFuncPtr*) &mSymbols.fGetActiveUniformBlockName, {{ "glGetActiveUniformBlockName" }} },
            { (PRFuncPtr*) &mSymbols.fUniformBlockBinding, {{ "glUniformBlockBinding" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::uniform_buffer_object);
    }

    if (IsSupported(GLFeature::uniform_matrix_nonsquare)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fUniformMatrix2x3fv, {{ "glUniformMatrix2x3fv" }} },
            { (PRFuncPtr*) &mSymbols.fUniformMatrix2x4fv, {{ "glUniformMatrix2x4fv" }} },
            { (PRFuncPtr*) &mSymbols.fUniformMatrix3x2fv, {{ "glUniformMatrix3x2fv" }} },
            { (PRFuncPtr*) &mSymbols.fUniformMatrix3x4fv, {{ "glUniformMatrix3x4fv" }} },
            { (PRFuncPtr*) &mSymbols.fUniformMatrix4x2fv, {{ "glUniformMatrix4x2fv" }} },
            { (PRFuncPtr*) &mSymbols.fUniformMatrix4x3fv, {{ "glUniformMatrix4x3fv" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::uniform_matrix_nonsquare);
    }

    if (IsSupported(GLFeature::internalformat_query)) {
        const SymLoadStruct symbols[] = {
            CORE_SYMBOL(GetInternalformativ),
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::internalformat_query);
    }

    if (IsSupported(GLFeature::invalidate_framebuffer)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fInvalidateFramebuffer,    {{ "glInvalidateFramebuffer" }} },
            { (PRFuncPtr*) &mSymbols.fInvalidateSubFramebuffer, {{ "glInvalidateSubFramebuffer" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::invalidate_framebuffer);
    }

    if (IsSupported(GLFeature::multiview)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fFramebufferTextureMultiview, {{
              "glFramebufferTextureMultiviewOVR",
              "glFramebufferTextureMultiviewLayeredANGLE"
            }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::multiview);
    }

    if (IsSupported(GLFeature::prim_restart)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fPrimitiveRestartIndex,    {{ "glPrimitiveRestartIndex", "glPrimitiveRestartIndexNV" }} },
            END_SYMBOLS
        };
        fnLoadForFeature(symbols, GLFeature::prim_restart);
    }

    if (IsExtensionSupported(KHR_debug)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fDebugMessageControl,  {{ "glDebugMessageControl",  "glDebugMessageControlKHR", }} },
            { (PRFuncPtr*) &mSymbols.fDebugMessageInsert,   {{ "glDebugMessageInsert",   "glDebugMessageInsertKHR",  }} },
            { (PRFuncPtr*) &mSymbols.fDebugMessageCallback, {{ "glDebugMessageCallback", "glDebugMessageCallbackKHR" }} },
            { (PRFuncPtr*) &mSymbols.fGetDebugMessageLog,   {{ "glGetDebugMessageLog",   "glGetDebugMessageLogKHR",  }} },
            { (PRFuncPtr*) &mSymbols.fGetPointerv,          {{ "glGetPointerv",          "glGetPointervKHR",         }} },
            { (PRFuncPtr*) &mSymbols.fPushDebugGroup,       {{ "glPushDebugGroup",       "glPushDebugGroupKHR",      }} },
            { (PRFuncPtr*) &mSymbols.fPopDebugGroup,        {{ "glPopDebugGroup",        "glPopDebugGroupKHR",       }} },
            { (PRFuncPtr*) &mSymbols.fObjectLabel,          {{ "glObjectLabel",          "glObjectLabelKHR",         }} },
            { (PRFuncPtr*) &mSymbols.fGetObjectLabel,       {{ "glGetObjectLabel",       "glGetObjectLabelKHR",      }} },
            { (PRFuncPtr*) &mSymbols.fObjectPtrLabel,       {{ "glObjectPtrLabel",       "glObjectPtrLabelKHR",      }} },
            { (PRFuncPtr*) &mSymbols.fGetObjectPtrLabel,    {{ "glGetObjectPtrLabel",    "glGetObjectPtrLabelKHR",   }} },
            END_SYMBOLS
        };
        fnLoadForExt(symbols, KHR_debug);
    }

    if (IsExtensionSupported(NV_fence)) {
        const SymLoadStruct symbols[] = {
            { (PRFuncPtr*) &mSymbols.fGenFences,    {{ "glGenFencesNV"    }} },
            { (PRFuncPtr*) &mSymbols.fDeleteFences, {{ "glDeleteFencesNV" }} },
            { (PRFuncPtr*) &mSymbols.fSetFence,     {{ "glSetFenceNV"     }} },
            { (PRFuncPtr*) &mSymbols.fTestFence,    {{ "glTestFenceNV"    }} },
            { (PRFuncPtr*) &mSymbols.fFinishFence,  {{ "glFinishFenceNV"  }} },
            { (PRFuncPtr*) &mSymbols.fIsFence,      {{ "glIsFenceNV"      }} },
            { (PRFuncPtr*) &mSymbols.fGetFenceiv,   {{ "glGetFenceivNV"   }} },
            END_SYMBOLS
        };
        fnLoadForExt(symbols, NV_fence);
    }

  // clang-format on

  if (IsExtensionSupported(NV_texture_barrier)) {
    const SymLoadStruct symbols[] = {
        {(PRFuncPtr*)&mSymbols.fTextureBarrier, {{"glTextureBarrierNV"}}},
        END_SYMBOLS};
    fnLoadForExt(symbols, NV_texture_barrier);
  }

  if (IsSupported(GLFeature::read_buffer)) {
    const SymLoadStruct symbols[] = {CORE_SYMBOL(ReadBuffer), END_SYMBOLS};
    fnLoadForFeature(symbols, GLFeature::read_buffer);
  }

  if (IsExtensionSupported(APPLE_framebuffer_multisample)) {
    const SymLoadStruct symbols[] = {
        CORE_SYMBOL(ResolveMultisampleFramebufferAPPLE), END_SYMBOLS};
    fnLoadForExt(symbols, APPLE_framebuffer_multisample);
  }

  if (IsSupported(GLFeature::provoking_vertex)) {
    const SymLoadStruct symbols[] = {{(PRFuncPtr*)&mSymbols.fProvokingVertex,
                                      {{
                                          "glProvokingVertex",
                                          "glProvokingVertexANGLE",
                                          "glProvokingVertexEXT",
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