OpenGL: Support B2T and T2T copies with BC formats

This patch implements the creation, buffer-to-texture copies and
texture-to-texture copies with BC formats on OpenGL backend. Note that
OpenGL SPEC also has the same issue about texture-to-texture copies
with compressed textures as Vulkan SPEC, so we have to skip the related
case.

The texture-to-buffer copies with BC formats and related end2end tests
will be supported in the following patches.

BUG=dawn:42
TEST=dawn_end2end_tests

Change-Id: I76b16862259cb2df77f202ed7ed433d41aa3cd47
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/10220
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: Austin Eng <enga@chromium.org>

generator/opengl_loader_generator.py

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import os, sys
+import os, json, sys
 from collections import namedtuple
 import xml.etree.ElementTree as etree
 
@@ -96,12 +96,13 @@ EnumDefine = namedtuple('EnumDefine', ['name', 'value'])
 Version = namedtuple('Version', ['major', 'minor'])
 VersionBlock = namedtuple('VersionBlock', ['version', 'procs', 'enums'])
 HeaderBlock = namedtuple('HeaderBlock', ['description', 'procs', 'enums'])
+ExtensionBlock = namedtuple('ExtensionBlock', ['extension', 'procs', 'enums', 'supported_specs'])
 
 def parse_version(version):
     return Version(*map(int, version.split('.')))
 
 
-def compute_params(root):
+def compute_params(root, supported_extensions):
     # Parse all the commands and enums
     all_procs = {}
     for command in root.findall('''commands[@namespace='GL']/command'''):
@@ -146,6 +147,31 @@ def compute_params(root):
     gles_blocks = parse_version_blocks('gles2')
     desktop_gl_blocks = parse_version_blocks('gl', core_removed_procs)
 
+    def parse_extension_block(extension):
+        section = root.find('''extensions/extension[@name='{}']'''.format(extension))
+        supported_specs = section.attrib['supported'].split('|')
+        section_procs = []
+        for command in section.findall('./require/command'):
+            proc_name = command.attrib['name']
+            assert(all_procs[proc_name].alias == None)
+            if proc_name not in removed_procs:
+                section_procs.append(all_procs[proc_name])
+
+        section_enums = []
+        for enum in section.findall('./require/enum'):
+            section_enums.append(all_enums[enum.attrib['name']])
+
+        return ExtensionBlock(extension, section_procs, section_enums, supported_specs)
+
+    extension_desktop_gl_blocks = [];
+    extension_gles_blocks = [];
+    for extension in supported_extensions:
+        extension_block = parse_extension_block(extension)
+        if 'gl' in extension_block.supported_specs:
+            extension_desktop_gl_blocks.append(extension_block)
+        if 'gles2' in extension_block.supported_specs:
+            extension_gles_blocks.append(extension_block)
+
     # Compute the blocks for headers such that there is no duplicate definition
     already_added_header_procs = set()
     already_added_header_enums = set()
@@ -172,9 +198,17 @@ def compute_params(root):
     for block in desktop_gl_blocks:
         add_header_block('Desktop OpenGL {}.{}'.format(block.version.major, block.version.minor), block)
 
+    for block in extension_desktop_gl_blocks:
+        add_header_block(block.extension, block)
+
+    for block in extension_gles_blocks:
+        add_header_block(block.extension, block)
+
     return {
         'gles_blocks': gles_blocks,
         'desktop_gl_blocks': desktop_gl_blocks,
+        'extension_desktop_gl_blocks': extension_desktop_gl_blocks,
+        'extension_gles_blocks': extension_gles_blocks,
         'header_blocks': header_blocks,
     }
 
@@ -183,10 +217,16 @@ class OpenGLLoaderGenerator(Generator):
         return 'Generates code to load OpenGL function pointers'
 
     def add_commandline_arguments(self, parser):
-        parser.add_argument('--gl-xml', required=True, type=str, help ='The Khronos gl.xml to use.')
+        parser.add_argument('--gl-xml', required=True, type=str, help='The Khronos gl.xml to use.')
+        parser.add_argument('--supported-extensions', required=True, type=str, help ='The JSON file that defines the OpenGL and GLES extensions to use.')
 
     def get_file_renders(self, args):
-        params = compute_params(etree.parse(args.gl_xml).getroot())
+        supported_extensions = []
+        with open(args.supported_extensions) as f:
+            supported_extensions_json = json.loads(f.read())
+            supported_extensions = supported_extensions_json['supported_extensions']
+
+        params = compute_params(etree.parse(args.gl_xml).getroot(), supported_extensions)
 
         return [
             FileRender('opengl/OpenGLFunctionsBase.cpp', 'dawn_native/opengl/OpenGLFunctionsBase_autogen.cpp', [params]),