Take GL version and extensions correctly into account when binding functions

ui/gl/generate_bindings.py

Index: ui/gl/generate_bindings.py
diff --git a/ui/gl/generate_bindings.py b/ui/gl/generate_bindings.py
index 98c75028bb515f4da108c0d18b603c0e7d85dfcc..a39a670d0b7c0630a2bc2877ffaeea68e3b381a4 100755
--- a/ui/gl/generate_bindings.py
+++ b/ui/gl/generate_bindings.py
@@ -11,6 +11,25 @@ import collections
 import re
 import sys
 
+"""In case there are multiple versions of the same function, one that's listed
+first takes priority if its conditions are met. If the function is an extension
+function, finding the extension from the extension string is a condition for
+binding it. The last version of the function is treated as a fallback option in
+case no other versions were bound, so a non-null function pointer in the
+bindings does not guarantee that the function is supported.
+
+Function binding conditions can be specified manually by supplying a versions
+array instead of the names array. Each version has the following keys:
+   name: Mandatory. Name of the function. Multiple versions can have the same
+         name but different conditions.
+   gl_versions: List of GL versions where the function is found.
+   extension/extensions: Extensions where the function is found. If not
+                         specified, the extensions are determined based on GL
+                         header files.
+                         If the function exists in an extension header, you
+                         may specify an empty array to prevent making that a
+                         condition for binding.
+"""
 GL_FUNCTIONS = [
 { 'return_type': 'void',
   'names': ['glActiveTexture'],
@@ -313,11 +332,13 @@ GL_FUNCTIONS = [
   'names': ['glGetIntegerv'],
   'arguments': 'GLenum pname, GLint* params', },
 { 'return_type': 'void',
-  'names': ['glGetProgramBinary', 'glGetProgramBinaryOES'],
+  'known_as': 'glGetProgramBinary',
+  'versions': [{ 'name': 'glGetProgramBinaryOES' },
+               { 'name': 'glGetProgramBinary',
+                 'extension': 'GL_ARB_get_program_binary' },
+               { 'name': 'glGetProgramBinary' }],
   'arguments': 'GLuint program, GLsizei bufSize, GLsizei* length, '
-               'GLenum* binaryFormat, GLvoid* binary',
-  'other_extensions': ['ARB_get_program_binary',
-                       'OES_get_program_binary'] },
+               'GLenum* binaryFormat, GLvoid* binary' },
 { 'return_type': 'void',
   'names': ['glGetProgramiv'],
   'arguments': 'GLuint program, GLenum pname, GLint* params', },
@@ -435,7 +456,8 @@ GL_FUNCTIONS = [
   'names': ['glLinkProgram'],
   'arguments': 'GLuint program', },
 { 'return_type': 'void*',
-  'names': ['glMapBuffer', 'glMapBufferOES'],
+  'known_as': 'glMapBuffer',
+  'names': ['glMapBufferOES', 'glMapBuffer'],
   'arguments': 'GLenum target, GLenum access', },
 { 'return_type': 'void*',
   'names': ['glMapBufferRange'],
@@ -454,15 +476,18 @@ GL_FUNCTIONS = [
   'names': ['glPolygonOffset'],
   'arguments': 'GLfloat factor, GLfloat units', },
 { 'return_type': 'void',
-  'names': ['glProgramBinary', 'glProgramBinaryOES'],
+  'known_as': 'glProgramBinary',
+  'versions': [{ 'name': 'glProgramBinaryOES' },
+               { 'name': 'glProgramBinary',
+                 'extension': 'GL_ARB_get_program_binary' },
+               { 'name': 'glProgramBinary' }],
   'arguments': 'GLuint program, GLenum binaryFormat, '
-               'const GLvoid* binary, GLsizei length',
-  'other_extensions': ['ARB_get_program_binary',
-                       'OES_get_program_binary'] },
+               'const GLvoid* binary, GLsizei length' },
 { 'return_type': 'void',
-  'names': ['glProgramParameteri'],
-  'arguments': 'GLuint program, GLenum pname, GLint value',
-  'other_extensions': ['ARB_get_program_binary'] },
+  'versions': [{ 'name': 'glProgramParameteri',
+                 'extension': 'GL_ARB_get_program_binary' },
+               { 'name': 'glProgramParameteri' }],
+  'arguments': 'GLuint program, GLenum pname, GLint value' },
 { 'return_type': 'void',
   'names': ['glQueryCounter'],
   'arguments': 'GLuint id, GLenum target', },
@@ -477,6 +502,10 @@ GL_FUNCTIONS = [
 { 'return_type': 'void',
   'names': ['glReleaseShaderCompiler'],
   'arguments': 'void', },
+# Multiple definitions of the same function like this cause weirdness in the
+# mock bindings and add overhead. However, some devices perform worse with the
+# ES3 core multisampling compared to an extension, which complicates combining
+# the functions to one.
 { 'return_type': 'void',
   'names': ['glRenderbufferStorageMultisample'],
   'arguments': 'GLenum target, GLsizei samples, GLenum internalformat, '
@@ -511,8 +540,8 @@ GL_FUNCTIONS = [
                'const void* binary, GLsizei length', },
 { 'return_type': 'void',
   'names': ['glShaderSource'],
-  'arguments':
-      'GLuint shader, GLsizei count, const char* const* str, const GLint* length',
+  'arguments': 'GLuint shader, GLsizei count, const char* const* str, '
+               'const GLint* length',
   'logging_code': """
   GL_SERVICE_LOG_CODE_BLOCK({
     for (GLsizei ii = 0; ii < count; ++ii) {
@@ -636,7 +665,8 @@ GL_FUNCTIONS = [
   'arguments': 'GLint location, GLsizei count, '
                'GLboolean transpose, const GLfloat* value', },
 { 'return_type': 'GLboolean',
-  'names': ['glUnmapBuffer', 'glUnmapBufferOES'],
+  'known_as': 'glUnmapBuffer',
+  'names': ['glUnmapBufferOES', 'glUnmapBuffer'],
   'arguments': 'GLenum target', },
 { 'return_type': 'void',
   'names': ['glUseProgram'],
@@ -712,51 +742,67 @@ GL_FUNCTIONS = [
   'arguments':
     'GLsync sync, GLbitfield flags, GLuint64 timeout', },
 { 'return_type': 'void',
-  'names': ['glDrawArraysInstancedANGLE', 'glDrawArraysInstancedARB'],
+  'known_as': 'glDrawArraysInstancedANGLE',
+  'names': ['glDrawArraysInstancedARB', 'glDrawArraysInstancedANGLE'],
   'arguments': 'GLenum mode, GLint first, GLsizei count, GLsizei primcount', },
 { 'return_type': 'void',
-  'names': ['glDrawElementsInstancedANGLE', 'glDrawElementsInstancedARB'],
+  'known_as': 'glDrawElementsInstancedANGLE',
+  'names': ['glDrawElementsInstancedARB', 'glDrawElementsInstancedANGLE'],
   'arguments':
       'GLenum mode, GLsizei count, GLenum type, const void* indices, '
       'GLsizei primcount', },
 { 'return_type': 'void',
-  'names': ['glVertexAttribDivisorANGLE', 'glVertexAttribDivisorARB'],
+  'known_as': 'glVertexAttribDivisorANGLE',
+  'names': ['glVertexAttribDivisorARB', 'glVertexAttribDivisorANGLE'],
   'arguments':
       'GLuint index, GLuint divisor', },
 { 'return_type': 'void',
-  'names': ['glGenVertexArraysOES',
-            'glGenVertexArraysAPPLE',
-            'glGenVertexArrays'],
-  'arguments': 'GLsizei n, GLuint* arrays',
-  'other_extensions': ['OES_vertex_array_object',
-                       'APPLE_vertex_array_object',
-                       'ARB_vertex_array_object'] },
-{ 'return_type': 'void',
-  'names': ['glDeleteVertexArraysOES',
-            'glDeleteVertexArraysAPPLE',
-            'glDeleteVertexArrays'],
-  'arguments': 'GLsizei n, const GLuint* arrays',
-  'other_extensions': ['OES_vertex_array_object',
-                       'APPLE_vertex_array_object',
-                       'ARB_vertex_array_object'] },
-{ 'return_type': 'void',
-  'names': ['glBindVertexArrayOES',
-            'glBindVertexArrayAPPLE',
-            'glBindVertexArray'],
-  'arguments': 'GLuint array',
-  'other_extensions': ['OES_vertex_array_object',
-                       'APPLE_vertex_array_object',
-                       'ARB_vertex_array_object'] },
+  'known_as': 'glGenVertexArraysOES',
+  'versions': [{ 'name': 'glGenVertexArrays',
+                 'gl_versions': ['gl3', 'gl4'] },
+               { 'name': 'glGenVertexArrays',
+                 'extension': 'GL_ARB_vertex_array_object' },
+               { 'name': 'glGenVertexArraysOES' },
+               { 'name': 'glGenVertexArraysAPPLE',
+                 'extension': 'GL_APPLE_vertex_array_object' }],
+  'arguments': 'GLsizei n, GLuint* arrays', },
+{ 'return_type': 'void',
+  'known_as': 'glDeleteVertexArraysOES',
+  'versions': [{ 'name': 'glDeleteVertexArrays',
+                 'gl_versions': ['gl3', 'gl4'] },
+               { 'name': 'glDeleteVertexArrays',
+                 'extension': 'GL_ARB_vertex_array_object' },
+               { 'name': 'glDeleteVertexArraysOES' },
+               { 'name': 'glDeleteVertexArraysAPPLE',
+                 'extension': 'GL_APPLE_vertex_array_object' }],
+  'arguments': 'GLsizei n, const GLuint* arrays' },
+{ 'return_type': 'void',
+  'known_as': 'glBindVertexArrayOES',
+  'versions': [{ 'name': 'glBindVertexArray',
+                 'gl_versions': ['gl3', 'gl4'] },
+               { 'name': 'glBindVertexArray',
+                 'extension': 'GL_ARB_vertex_array_object' },
+               { 'name': 'glBindVertexArrayOES' },
+               { 'name': 'glBindVertexArrayAPPLE',
+                 'extension': 'GL_APPLE_vertex_array_object' }],
+  'arguments': 'GLuint array' },
 { 'return_type': 'GLboolean',
-  'names': ['glIsVertexArrayOES',
-            'glIsVertexArrayAPPLE',
-            'glIsVertexArray'],
-  'arguments': 'GLuint array',
-  'other_extensions': ['OES_vertex_array_object',
-                       'APPLE_vertex_array_object',
-                       'ARB_vertex_array_object'] },
-{ 'return_type': 'void',
-  'names': ['glDiscardFramebufferEXT', 'glInvalidateFramebuffer'],
+  'known_as': 'glIsVertexArrayOES',
+  'versions': [{ 'name': 'glIsVertexArray',
+                 'gl_versions': ['gl3', 'gl4'] },
+               { 'name': 'glIsVertexArray',
+                 'extension': 'GL_ARB_vertex_array_object' },
+               { 'name': 'glIsVertexArrayOES' },
+               { 'name': 'glIsVertexArrayAPPLE',
+                 'extension': 'GL_APPLE_vertex_array_object' }],
+  'arguments': 'GLuint array' },
+{ 'return_type': 'void',
+  'known_as': 'glDiscardFramebufferEXT',
+  'versions': [{ 'name': 'glInvalidateFramebuffer',
+                 'gl_versions': ['es3'],
+                 'extensions': [] },
+               { 'name': 'glDiscardFramebufferEXT',
+                 'gl_versions': ['es1', 'es2'] }],
   'arguments': 'GLenum target, GLsizei numAttachments, '
       'const GLenum* attachments' },
 ]
@@ -832,15 +878,15 @@ EGL_FUNCTIONS = [
   'arguments':
       'EGLDisplay dpy, EGLConfig config, EGLint attribute, EGLint* value', },
 { 'return_type': 'EGLImageKHR',
-  'names': ['eglCreateImageKHR'],
+  'versions': [{ 'name': 'eglCreateImageKHR',
+                 'extension': 'EGL_KHR_image_base' }],
   'arguments':
       'EGLDisplay dpy, EGLContext ctx, EGLenum target, EGLClientBuffer buffer, '
-      'const EGLint* attrib_list',
-  'other_extensions': ['EGL_KHR_image_base'] },
+      'const EGLint* attrib_list' },
 { 'return_type': 'EGLBoolean',
-  'names': ['eglDestroyImageKHR'],
-  'arguments': 'EGLDisplay dpy, EGLImageKHR image',
-  'other_extensions': ['EGL_KHR_image_base'] },
+  'versions': [{ 'name' : 'eglDestroyImageKHR',
+                 'extension': 'EGL_KHR_image_base' }],
+  'arguments': 'EGLDisplay dpy, EGLImageKHR image' },
 { 'return_type': 'EGLSurface',
   'names': ['eglCreateWindowSurface'],
   'arguments': 'EGLDisplay dpy, EGLConfig config, EGLNativeWindowType win, '
@@ -938,23 +984,23 @@ EGL_FUNCTIONS = [
   'arguments':
       'EGLDisplay dpy, EGLSurface surface, EGLint attribute, void** value', },
 { 'return_type': 'EGLSyncKHR',
-  'names': ['eglCreateSyncKHR'],
-  'arguments': 'EGLDisplay dpy, EGLenum type, const EGLint* attrib_list',
-  'other_extensions': ['EGL_KHR_fence_sync'] },
+  'versions': [{ 'name': 'eglCreateSyncKHR',
+                 'extension': 'EGL_KHR_fence_sync' }],
+  'arguments': 'EGLDisplay dpy, EGLenum type, const EGLint* attrib_list' },
 { 'return_type': 'EGLint',
-  'names': ['eglClientWaitSyncKHR'],
+  'versions': [{ 'name': 'eglClientWaitSyncKHR',
+                 'extension': 'EGL_KHR_fence_sync' }],
   'arguments': 'EGLDisplay dpy, EGLSyncKHR sync, EGLint flags, '
-      'EGLTimeKHR timeout',
-  'other_extensions': ['EGL_KHR_fence_sync'] },
+      'EGLTimeKHR timeout' },
 { 'return_type': 'EGLBoolean',
-  'names': ['eglGetSyncAttribKHR'],
+  'versions': [{ 'name': 'eglGetSyncAttribKHR',
+                 'extension': 'EGL_KHR_fence_sync' }],
   'arguments': 'EGLDisplay dpy, EGLSyncKHR sync, EGLint attribute, '
-      'EGLint* value',
-  'other_extensions': ['EGL_KHR_fence_sync'] },
+      'EGLint* value' },
 { 'return_type': 'EGLBoolean',
-  'names': ['eglDestroySyncKHR'],
-  'arguments': 'EGLDisplay dpy, EGLSyncKHR sync',
-  'other_extensions': ['EGL_KHR_fence_sync'] },
+  'versions': [{ 'name': 'eglDestroySyncKHR',
+                 'extension': 'EGL_KHR_fence_sync' }],
+  'arguments': 'EGLDisplay dpy, EGLSyncKHR sync' },
 { 'return_type': 'EGLBoolean',
   'names': ['eglGetSyncValuesCHROMIUM'],
   'arguments':
@@ -962,9 +1008,9 @@ EGL_FUNCTIONS = [
       'EGLuint64CHROMIUM* ust, EGLuint64CHROMIUM* msc, '
       'EGLuint64CHROMIUM* sbc', },
 { 'return_type': 'EGLint',
-  'names': ['eglWaitSyncKHR'],
-  'arguments': 'EGLDisplay dpy, EGLSyncKHR sync, EGLint flags',
-  'other_extensions': ['EGL_KHR_wait_sync'] },
+  'versions': [{ 'name': 'eglWaitSyncKHR',
+                 'extension': 'EGL_KHR_fence_sync' }],
+  'arguments': 'EGLDisplay dpy, EGLSyncKHR sync, EGLint flags' }
 ]
 
 WGL_FUNCTIONS = [
@@ -1214,7 +1260,7 @@ FUNCTION_SETS = [
   [GLX_FUNCTIONS, 'glx', ['GL/glx.h', 'GL/glxext.h'], []],
 ]
 
-def GenerateHeader(file, functions, set_name, used_extension_functions):
+def GenerateHeader(file, functions, set_name, used_extensions):
   """Generates gl_bindings_autogen_x.h"""
 
   # Write file header.
@@ -1239,12 +1285,12 @@ class GLContext;
   file.write('\n')
   for func in functions:
     file.write('typedef %s (GL_BINDING_CALL *%sProc)(%s);\n' %
-        (func['return_type'], func['names'][0], func['arguments']))
+        (func['return_type'], func['known_as'], func['arguments']))
 
   # Write declarations for booleans indicating which extensions are available.
   file.write('\n')
   file.write("struct Extensions%s {\n" % set_name.upper())
-  for extension, ext_functions in used_extension_functions:
+  for extension in used_extensions:
     file.write('  bool b_%s;\n' % extension)
   file.write('};\n')
   file.write('\n')
@@ -1252,7 +1298,7 @@ class GLContext;
   # Write Procs struct.
   file.write("struct Procs%s {\n" % set_name.upper())
   for func in functions:
-    file.write('  %sProc %sFn;\n' % (func['names'][0], func['names'][0]))
+    file.write('  %sProc %sFn;\n' % (func['known_as'], func['known_as']))
   file.write('};\n')
   file.write('\n')
 
@@ -1266,7 +1312,7 @@ class GLContext;
 """ % {'name': set_name.upper()})
   for func in functions:
     file.write('  virtual %s %sFn(%s) = 0;\n' %
-      (func['return_type'], func['names'][0], func['arguments']))
+      (func['return_type'], func['known_as'], func['arguments']))
   file.write('};\n')
   file.write('\n')
 
@@ -1277,14 +1323,14 @@ class GLContext;
   file.write('\n')
   for func in functions:
     file.write('#define %s ::gfx::g_current_%s_context->%sFn\n' %
-        (func['names'][0], set_name.lower(), func['names'][0]))
+        (func['known_as'], set_name.lower(), func['known_as']))
 
   file.write('\n')
   file.write('#endif  //  UI_GFX_GL_GL_BINDINGS_AUTOGEN_%s_H_\n' %
       set_name.upper())
 
 
-def GenerateAPIHeader(file, functions, set_name, used_extension_functions):
+def GenerateAPIHeader(file, functions, set_name):
   """Generates gl_bindings_api_autogen_x.h"""
 
   # Write file header.
@@ -1300,12 +1346,12 @@ def GenerateAPIHeader(file, functions, set_name, used_extension_functions):
   # Write API declaration.
   for func in functions:
     file.write('  virtual %s %sFn(%s) OVERRIDE;\n' %
-      (func['return_type'], func['names'][0], func['arguments']))
+      (func['return_type'], func['known_as'], func['arguments']))
 
   file.write('\n')
 
 
-def GenerateMockHeader(file, functions, set_name, used_extension_functions):
+def GenerateMockHeader(file, functions, set_name):
   """Generates gl_mock_autogen_x.h"""
 
   # Write file header.
@@ -1327,13 +1373,12 @@ def GenerateMockHeader(file, functions, set_name, used_extension_functions):
     if len(args):
       arg_count = func['arguments'].count(',') + 1
     file.write('  MOCK_METHOD%d(%s, %s(%s));\n' %
-      (arg_count, func['names'][0][2:], func['return_type'], args))
+      (arg_count, func['known_as'][2:], func['return_type'], args))
 
   file.write('\n')
 
 
-def GenerateInterfaceHeader(
-    file, functions, set_name, used_extension_functions):
+def GenerateInterfaceHeader(file, functions, set_name):
   """Generates gl_interface_autogen_x.h"""
 
   # Write file header.
@@ -1352,12 +1397,12 @@ def GenerateInterfaceHeader(
     if args == 'void':
       args = ''
     file.write('  virtual %s %s(%s) = 0;\n' %
-      (func['return_type'], func['names'][0][2:], args))
+      (func['return_type'], func['known_as'][2:], args))
 
   file.write('\n')
 
 
-def GenerateSource(file, functions, set_name, used_extension_functions):
+def GenerateSource(file, functions, set_name, used_extensions):
   """Generates gl_bindings_autogen_x.cc"""
 
   # Write file header.
@@ -1374,6 +1419,7 @@ def GenerateSource(file, functions, set_name, used_extension_functions):
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_implementation.h"
+#include "ui/gl/gl_version_info.h"
 #include "ui/gl/gl_%s_api_implementation.h"
 
 using gpu::gles2::GLES2Util;
@@ -1387,61 +1433,119 @@ namespace gfx {
   file.write('Driver%s g_driver_%s;\n' % (set_name.upper(), set_name.lower()))
   file.write('\n')
 
-  # Write function to initialize the core function pointers. The code assumes
-  # any non-NULL pointer returned by GetGLCoreProcAddress() is valid, although
-  # it may be overwritten by an extension function pointer later.
+  # Write function to initialize the function pointers that are always the same.
   file.write('\n')
-  file.write('void Driver%s::InitializeBindings() {\n' %
+  file.write('void Driver%s::InitializeStaticBindings() {\n' %
              set_name.upper())
+
+  def WriteFuncBinding(file, known_as, version_name):
+    file.write(
+        '  fn.%sFn = reinterpret_cast<%sProc>(GetGLProcAddress("%s"));\n' %
+        (known_as, known_as, version_name))
+
   for func in functions:
-    first_name = func['names'][0]
-    for i, name in enumerate(func['names']):
-      if i:
-        file.write('  if (!fn.%sFn)\n  ' % first_name)
-      file.write(
-          '  fn.%sFn = reinterpret_cast<%sProc>('
-          'GetGLCoreProcAddress("%s"));\n' %
-          (first_name, first_name, name))
+    if len(func['names']) == 1:
+      WriteFuncBinding(file, func['known_as'], func['known_as'])
+
   file.write('}\n')
   file.write('\n')
 
-  # Write function to initialize the extension function pointers. This function
-  # uses a current context to query which extensions are actually supported.
-  file.write("""void Driver%s::InitializeExtensionBindings(
-    GLContext* context) {
+  # Write function to initialize bindings where choice of the function depends
+  # on the extension string or the GL version.
+  file.write("""void Driver%s::InitializeDynamicBindings(GLContext* context) {
+  DCHECK(context && context->IsCurrent(NULL));
+  const GLVersionInfo* ver ALLOW_UNUSED = context->GetVersionInfo();
+  std::string extensions ALLOW_UNUSED = context->GetExtensions();
+  extensions += " ";
+
 """ % set_name.upper())
-  file.write('  DCHECK(context && context->IsCurrent(NULL));\n')
-  for extension, ext_functions in used_extension_functions:
-    file.write('  ext.b_%s = context->HasExtension("%s");\n' %
+  for extension in used_extensions:
+    # Extra space at the end of the extension name is intentional, it is used
+    # as a separator
+    file.write('  ext.b_%s = extensions.find("%s ") != std::string::npos;\n' %
         (extension, extension))
-    file.write('  if (ext.b_%s) {\n' %
-        (extension))
-    queried_entry_points = set()
-    for entry_point_name, function_name in ext_functions:
-      # Replace the pointer unconditionally unless this extension has several
-      # alternatives for the same entry point (e.g.,
-      # GL_ARB_blend_func_extended).
-      if entry_point_name in queried_entry_points:
-        file.write('    if (!fn.%sFn)\n  ' % entry_point_name)
-      file.write(
-         '    fn.%sFn = reinterpret_cast<%sProc>(GetGLProcAddress("%s"));\n' %
-             (entry_point_name, entry_point_name, function_name))
-      queried_entry_points.add(entry_point_name)
-    file.write('  }\n')
+
+  def VersionCondition(version):
+    conditions = []
+    if 'gl_versions' in version:
+      gl_versions = version['gl_versions']
+      version_cond = ' || '.join(['ver->is_%s' % gl for gl in gl_versions])
+      conditions.append(version_cond)
+    ext = []
+    if 'extension' in version:
+      ext.append(version['extension'])
+    if 'extensions' in version:
+      ext.extend([e for e in version['extensions'] if e not in ext])
+    if ext:
+      ext_cond = ' || '.join(['ext.b_%s' % e for e in ext])
+      conditions.append(ext_cond)
+    def Wrap(cond):
+      if ' || ' in cond:
+        return '(%s)' % cond
+      return cond
+    return ' && '.join([Wrap(cond) for cond in conditions])
+
+  def WriteConditionalFuncBinding(file, func):
+    assert len(func['versions']) > 1
+    known_as = func['known_as']
+    i = 0
+    first_version = True
+    while i < len(func['versions']):
+      version = func['versions'][i]
+      cond = VersionCondition(version)
+      combined_conditions = [cond]
+      while i + 1 < len(func['versions']) and \
+          func['versions'][i + 1]['name'] == version['name']:
+        i += 1
+        combined_conditions.append(VersionCondition(func['versions'][i]))
+      if len(combined_conditions) > 1:
+        if [1 for cond in combined_conditions if cond == '']:
+          cond = ''
+        else:
+          def Wrap(cond):
+            if ' && ' in cond:
+              return '(%s)' % cond
+            return cond
+          cond = ' || '.join([Wrap(cond) for cond in combined_conditions])
+      # Don't make the last possible binding conditional on anything else but
+      # that the function isn't already bound to avoid verbose specification
+      # of functions which have both ARB and core versions with the same name,
+      # and to be able to bind to mock extension functions in unit tests which
+      # call InitializeDynamicGLBindings with a stub context that doesn't have
+      # extensions in its extension string.
+      # TODO(oetuaho@nvidia.com): Get rid of the fallback.
+      # http://crbug.com/325668
+      if cond != '' and i + 1 < len(func['versions']):
+        if not first_version:
+          file.write('  if (!fn.%sFn && (%s))\n  ' % (known_as, cond))

[piman, 2013/12/04 22:45:12]

How about '  else if (%s)\n  ' % cond ?
Presumably the previous line is an if, and is what may have set fn.*Fn

[oetuaho, 2013/12/05 09:47:14]

That should be correct, and would result in cleaner generated code. Same goes
for the if under "elif not first_version". However, changing these does risk
breaking compatibility with subtly bugged drivers, for example if a driver
advertises GL_ARB_vertex_buffer_object but actually exports only glDeleteBuffers
and glGenBuffers without the ARB postfix, or something similar. I don't have a
very good idea if bugs like this appear in the wild, but we should be careful
here. I'm leaning on leaving this as is, but we can change it if you have more
data on this.

[piman, 2013/12/05 19:47:04]

I see, you want to protect against buggy drivers that expose an extension, but
don't provide the entrypoints, givving them fallback options. I buy that.

+        else:
+          file.write('  if (%s)\n  ' % cond)
+      elif not first_version:
+        file.write('  if (!fn.%sFn)\n  ' % known_as)
+      WriteFuncBinding(file, known_as, version['name'])
+      i += 1
+      first_version = False
+
+  for func in functions:
+    if len(func['names']) > 1:
+      file.write('\n')
+      WriteConditionalFuncBinding(file, func)
+
+  # Some new function pointers have been added, so update them in debug bindings
+  file.write('\n')
   file.write('  if (g_debugBindingsInitialized)\n')
-  file.write('    UpdateDebugExtensionBindings();\n')
+  file.write('    InitializeDebugBindings();\n')
   file.write('}\n')
   file.write('\n')
 
   # Write logging wrappers for each function.
   file.write('extern "C" {\n')
   for func in functions:
-    names = func['names']
     return_type = func['return_type']
     arguments = func['arguments']
     file.write('\n')
     file.write('static %s GL_BINDING_CALL Debug_%s(%s) {\n' %
-        (return_type, names[0], arguments))
+        (return_type, func['known_as'], arguments))
     argument_names = re.sub(
         r'(const )?[a-zA-Z0-9_]+\** ([a-zA-Z0-9_]+)', r'\2', arguments)
     argument_names = re.sub(
@@ -1463,9 +1567,9 @@ namespace gfx {
         log_argument_names)
     log_argument_names = re.sub(
         r'CONSTVOID_([a-zA-Z0-9_]+)',
-        r'static_cast<const void*>(\1)', log_argument_names);
+        r'static_cast<const void*>(\1)', log_argument_names)
     log_argument_names = re.sub(
-        r'CONSTCHAR_([a-zA-Z0-9_]+)', r'\1', log_argument_names);
+        r'CONSTCHAR_([a-zA-Z0-9_]+)', r'\1', log_argument_names)
     log_argument_names = re.sub(
         r'GLenum_([a-zA-Z0-9_]+)', r'GLES2Util::GetStringEnum(\1)',
         log_argument_names)
@@ -1478,7 +1582,7 @@ namespace gfx {
       log_argument_names = ''
     else:
       log_argument_names = " << " + log_argument_names
-    function_name = names[0]
+    function_name = func['known_as']
     if return_type == 'void':
       file.write('  GL_SERVICE_LOG("%s" << "(" %s << ")");\n' %
           (function_name, log_argument_names))
@@ -1494,7 +1598,7 @@ namespace gfx {
       if 'logging_code' in func:
         file.write("%s\n" % func['logging_code'])
       else:
-        file.write('  GL_SERVICE_LOG("GL_RESULT: " << result);\n');
+        file.write('  GL_SERVICE_LOG("GL_RESULT: " << result);\n')
       file.write('  return result;\n')
     file.write('}\n')
   file.write('}  // extern "C"\n')
@@ -1504,7 +1608,7 @@ namespace gfx {
   file.write('void Driver%s::InitializeDebugBindings() {\n' %
              set_name.upper())
   for func in functions:
-    first_name = func['names'][0]
+    first_name = func['known_as']
     file.write('  if (!debug_fn.%sFn) {\n' % first_name)
     file.write('    debug_fn.%sFn = fn.%sFn;\n' % (first_name, first_name))
     file.write('    fn.%sFn = Debug_%s;\n' % (first_name, first_name))
@@ -1512,20 +1616,6 @@ namespace gfx {
   file.write('  g_debugBindingsInitialized = true;\n')
   file.write('}\n')
 
-  # Write function to update the debug function pointers to extension functions
-  # after the extensions have been initialized.
-  file.write('\n')
-  file.write('void Driver%s::UpdateDebugExtensionBindings() {\n' %
-             set_name.upper())
-  for extension, ext_functions in used_extension_functions:
-    for name, _ in ext_functions:
-      file.write('  if (debug_fn.%sFn != fn.%sFn &&\n' % (name, name))
-      file.write('      fn.%sFn != Debug_%s) {\n' % (name, name))
-      file.write('    debug_fn.%sFn = fn.%sFn;\n' % (name, name))
-      file.write('    fn.%sFn = Debug_%s;\n' % (name, name))
-      file.write('  }\n')
-  file.write('}\n')
-
   # Write function to clear all function pointers.
   file.write('\n')
   file.write("""void Driver%s::ClearBindings() {
@@ -1535,19 +1625,18 @@ namespace gfx {
 
   # Write GLApiBase functions
   for func in functions:
-    names = func['names']
     return_type = func['return_type']
     arguments = func['arguments']
     file.write('\n')
     file.write('%s %sApiBase::%sFn(%s) {\n' %
-        (return_type, set_name.upper(), names[0], arguments))
+        (return_type, set_name.upper(), func['known_as'], arguments))
     argument_names = re.sub(
         r'(const )?[a-zA-Z0-9_]+\** ([a-zA-Z0-9_]+)', r'\2', arguments)
     argument_names = re.sub(
         r'(const )?[a-zA-Z0-9_]+\** ([a-zA-Z0-9_]+)', r'\2', argument_names)
     if argument_names == 'void' or argument_names == '':
       argument_names = ''
-    function_name = names[0]
+    function_name = func['known_as']
     if return_type == 'void':
       file.write('  driver_->fn.%sFn(%s);\n' %
           (function_name, argument_names))
@@ -1558,19 +1647,18 @@ namespace gfx {
 
   # Write TraceGLApi functions
   for func in functions:
-    names = func['names']
     return_type = func['return_type']
     arguments = func['arguments']
     file.write('\n')
     file.write('%s Trace%sApi::%sFn(%s) {\n' %
-        (return_type, set_name.upper(), names[0], arguments))
+        (return_type, set_name.upper(), func['known_as'], arguments))
     argument_names = re.sub(
         r'(const )?[a-zA-Z0-9_]+\** ([a-zA-Z0-9_]+)', r'\2', arguments)
     argument_names = re.sub(
         r'(const )?[a-zA-Z0-9_]+\** ([a-zA-Z0-9_]+)', r'\2', argument_names)
     if argument_names == 'void' or argument_names == '':
       argument_names = ''
-    function_name = names[0]
+    function_name = func['known_as']
     file.write('  TRACE_EVENT_BINARY_EFFICIENT0("gpu", "TraceGLAPI::%s")\n' %
                function_name)
     if return_type == 'void':
@@ -1605,12 +1693,12 @@ namespace gfx {
   for func in functions:
     file.write('\n')
     file.write('%s GL_BINDING_CALL Mock_%s(%s) {\n' %
-        (func['return_type'], func['names'][0], func['arguments']))
-    argument_names = re.sub(r'(const )?[a-zA-Z0-9]+((\s*const\s*)?\*)* ([a-zA-Z0-9]+)', r'\4',
-                              func['arguments'])
+        (func['return_type'], func['known_as'], func['arguments']))
+    argRe = r'(const )?[a-zA-Z0-9]+((\s*const\s*)?\*)* ([a-zA-Z0-9]+)'

[piman, 2013/12/04 22:45:12]

nit: style (arg_re)

[oetuaho, 2013/12/05 09:47:14]

Done.

+    argument_names = re.sub(argRe, r'\4', func['arguments'])
     if argument_names == 'void':
       argument_names = ''
-    function_name = func['names'][0][2:]
+    function_name = func['known_as'][2:]
     if func['return_type'] == 'void':
       file.write('  GLInterface::GetGLInterface()->%s(%s);\n' %
           (function_name, argument_names))
@@ -1631,12 +1719,13 @@ namespace gfx {
   file.write('\n')
   file.write('void* GL_BINDING_CALL GetMockGLProcAddress(const char* name) {\n')
   for func in functions:
-    first_name = func['names'][0]
-    file.write('  if (strcmp(name, "%s") == 0)\n' % first_name)
-    file.write('    return reinterpret_cast<void*>(Mock_%s);\n' % first_name)
+    for name in func['names']:
+      file.write('  if (strcmp(name, "%s") == 0)\n' % name)
+      file.write(
+          '    return reinterpret_cast<void*>(Mock_%s);\n' % func['known_as'])
   # Always return a non-NULL pointer like some EGL implementations do.
   file.write('  return reinterpret_cast<void*>(&MockInvalidFunction);\n')
-  file.write('}\n');
+  file.write('}\n')
 
   file.write('\n')
   file.write('}  // namespace gfx\n')
@@ -1719,49 +1808,51 @@ def LooksLikeExtensionFunction(function):
   return vendor is not None and not vendor.group(1) in ['GL', 'API', 'DC']
 
 
-def GetUsedExtensionFunctions(functions, extension_headers, extra_extensions):
-  """Determine which functions belong to extensions.
+def FillExtensionsFromHeaders(functions, extension_headers, extra_extensions):
+  """Determine which functions belong to extensions based on extension headers,
+  and fill in this information to the functions table for functions that don't
+  already have the information.
 
   Args:
-    functions: List of (return type, function names, arguments).
+    functions: List of (return type, function versions, arguments).
     extension_headers: List of header file names.
+    extra_extensions: Extensions to add to the list.
   Returns:
-    List of (extension name, [function name alternatives]) sorted with least
-    preferred extensions first.
+    List of used extensions.
   """
   # Parse known extensions.
   extensions = GetExtensionFunctions(extension_headers)
   functions_to_extensions = GetFunctionToExtensionMap(extensions)
 
-  # Collect all used extension functions.
-  used_extension_functions = collections.defaultdict(lambda: [])
+  # Fill in the extension information.
+  used_extensions = []
   for func in functions:
-    for name in func['names']:
-      # Make sure we know about all extension functions.
-      if (LooksLikeExtensionFunction(name) and
-          not name in functions_to_extensions):
+    for version in func['versions']:
+      name = version['name']
+      # Make sure we know about all extensions and extension functions.
+      if 'extension' in version:
+        if version['extension'] not in used_extensions:
+          used_extensions.append(version['extension'])
+      elif 'extensions' in version:
+        used_extensions.extend(
+            [e for e in version['extensions'] if e not in used_extensions])
+      elif name in functions_to_extensions:
+        # If there are multiple versions with the same name, assume that they
+        # already have all the correct conditions, we can't just blindly add
+        # the same extension conditions to all of them
+        if len([v for v in func['versions'] if v['name'] == name]) == 1:
+          version['extensions'] = functions_to_extensions[name]
+          used_extensions.extend(
+              [e for e in version['extensions'] if e not in used_extensions])
+      elif LooksLikeExtensionFunction(name):
         raise RuntimeError('%s looks like an extension function but does not '
             'belong to any of the known extensions.' % name)
-      if name in functions_to_extensions:
-        extensions = functions_to_extensions[name][:]
-        if 'other_extensions' in func:
-          extensions.extend(func['other_extensions'])
-        for extension in extensions:
-          used_extension_functions[extension].append((func['names'][0], name))
 
   # Add extensions that do not have any functions.
-  used_extension_functions.update(dict(
-      [(e, []) for e in extra_extensions if e not in used_extension_functions]))
+  used_extensions.extend(
+      [e for e in extra_extensions if e not in used_extensions])
 
-  def ExtensionSortKey(name):
-    # Prefer ratified extensions and EXTs.
-    preferences = ['_ARB_', '_OES_', '_EXT_', '']
-    for i, category in enumerate(preferences):
-      if category in name:
-        return -i
-  used_extension_functions = sorted(used_extension_functions.items(),
-      key = lambda item: ExtensionSortKey(item[0]))
-  return used_extension_functions
+  return used_extensions
 
 
 def ResolveHeader(header, header_paths):
@@ -1801,46 +1892,60 @@ def main(argv):
         print ResolveHeader(header, options.header_paths)
     return 0
 
+  directory = '.'
   if len(args) >= 1:
-    dir = args[0]
-  else:
-    dir = '.'
+    directory = args[0]
 
   for [functions, set_name, extension_headers, extensions] in FUNCTION_SETS:
+    # Function names can be specified in two ways (list of unique names or list
+    # of versions with different binding conditions), fill in the data both
+    # ways:
+    for func in functions:
+      assert 'versions' in func or 'names' in func, 'Function with no names'
+      if 'versions' not in func:
+        func['versions'] = [{'name': n} for n in func['names']]
+      if 'names' not in func:
+        func['names'] = []
+        for version in func['versions']:
+          if version['name'] not in func['names']:
+            func['names'].append(version['name'])
+      # Use the first version's name unless otherwise specified
+      if 'known_as' not in func:
+        func['known_as'] = func['names'][0]
+
     extension_headers = [ResolveHeader(h, options.header_paths)
                          for h in extension_headers]
-    used_extension_functions = GetUsedExtensionFunctions(
+    used_extensions = FillExtensionsFromHeaders(
         functions, extension_headers, extensions)
 
     header_file = open(
-        os.path.join(dir, 'gl_bindings_autogen_%s.h' % set_name), 'wb')
-    GenerateHeader(header_file, functions, set_name, used_extension_functions)
+        os.path.join(directory, 'gl_bindings_autogen_%s.h' % set_name), 'wb')
+    GenerateHeader(header_file, functions, set_name, used_extensions)
     header_file.close()
 
     header_file = open(
-        os.path.join(dir, 'gl_bindings_api_autogen_%s.h' % set_name), 'wb')
-    GenerateAPIHeader(
-        header_file, functions, set_name, used_extension_functions)
+        os.path.join(directory, 'gl_bindings_api_autogen_%s.h' % set_name),
+        'wb')
+    GenerateAPIHeader(header_file, functions, set_name)
     header_file.close()
 
     source_file = open(
-        os.path.join(dir, 'gl_bindings_autogen_%s.cc' % set_name), 'wb')
-    GenerateSource(source_file, functions, set_name, used_extension_functions)
+        os.path.join(directory, 'gl_bindings_autogen_%s.cc' % set_name), 'wb')
+    GenerateSource(source_file, functions, set_name, used_extensions)
     source_file.close()
 
     header_file = open(
-        os.path.join(dir, 'gl_interface_autogen_%s.h' % set_name), 'wb')
-    GenerateInterfaceHeader(
-        header_file, functions, set_name, used_extension_functions)
+        os.path.join(directory, 'gl_interface_autogen_%s.h' % set_name), 'wb')
+    GenerateInterfaceHeader(header_file, functions, set_name)
     header_file.close()
 
     header_file = open(
-        os.path.join(dir, 'gl_mock_autogen_%s.h' % set_name), 'wb')
-    GenerateMockHeader(
-        header_file, functions, set_name, used_extension_functions)
+        os.path.join(directory, 'gl_mock_autogen_%s.h' % set_name), 'wb')
+    GenerateMockHeader(header_file, functions, set_name)
     header_file.close()
 
-  source_file = open(os.path.join(dir, 'gl_bindings_autogen_mock.cc'), 'wb')
+  source_file = open(os.path.join(directory, 'gl_bindings_autogen_mock.cc'),
+                     'wb')
   GenerateMockSource(source_file, GL_FUNCTIONS)
   source_file.close()
   return 0