command_buffer: Fix setting samplers with bound uniforms

gpu/command_buffer/service/program_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/program_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 595 matching lines @@
       GLSLArrayName parsed_service_name(service_name);
       if (parsed_service_name.IsArrayName()) {
         service_base_name = parsed_service_name.base_name();
         GLSLArrayName parsed_client_name(client_name);
         client_base_name = parsed_client_name.base_name();
       } else {
         service_name += "[0]";
         client_name += "[0]";
       }
     }
 

[Kimmo Kinnunen, 2016/01/21 12:36:32]

(1): This binds the automatically bound uniforms to unused client locations.

     // Assign a location for the uniform: use either client-bound
     // location or automatically assigned to an unused location.
     size_t client_location_base = 0;
     LocationMap::const_iterator it =
         bind_uniform_location_map_.find(client_base_name);
     if (it != bind_uniform_location_map_.end()) {
       client_location_base = it->second;
     } else {
       while (unused_client_location_cursor < uniform_locations_.size() &&
              !uniform_locations_[unused_client_location_cursor].IsUnused())
@@ skipping 625 matching lines @@
   if (fake_location < 0)
     return nullptr;
   size_t location_index = static_cast<size_t>(fake_location);
   if (location_index >= fragment_input_locations_.size())
     return nullptr;
   if (!fragment_input_locations_[location_index].IsActive())
     return nullptr;
   return fragment_input_locations_[location_index].shader_variable();
 }
 
 bool Program::IsInactiveFragmentInputLocationByFakeLocation(

[Kimmo Kinnunen, 2016/01/21 12:36:32]

(2): This is the place that is checking the possibility that the driver
optimized the uniform away.

This will be executed by:
GLES2DecoderImpl::DoUniform1iv
 GLES2DecoderImpl::PrepForSetUniformByLocation
  GLES2DecoderImpl::CheckCurrentProgramForUniform
   Program::GetFragmentInputInfoByFakeLocation

     GLint fake_location) const {
   if (fake_location < 0)
     return true;
   size_t location_index = static_cast<size_t>(fake_location);
   if (location_index >= fragment_input_locations_.size())
     return false;
   return fragment_input_locations_[location_index].IsInactive();
 }
 
 bool Program::SetUniformLocationBinding(
@@ skipping 130 matching lines @@
 }
 
 bool Program::SetSamplers(
     GLint num_texture_units, GLint fake_location,
     GLsizei count, const GLint* value) {
   if (fake_location < 0) {
     return true;
   }
   size_t location_index =
       GetUniformLocationIndexFromFakeLocation(fake_location);
-  if (location_index >= uniform_infos_.size())
+  if (location_index >= uniform_locations_.size())

[Zhenyao Mo, 2016/01/20 18:41:13]

Correct me if I am wrong.

uniform_locations_ size is defined by the largest client bound location.  If the
client does not bind a uniform location, that location could still be a valid
location - it's just automatically bound to a uniform by the driver.

Also, even if the client binds to a specific location, the underlying uniform
could still be optimized away, or the name does not corresponding to a uniform
at all.

Is that the case?  If yes, then I don't think this change works in general.

[Kimmo Kinnunen, 2016/01/21 12:36:32]

No, automatically bound uniforms get their client-side uniform locations
assigned by the command buffer.
See above (1).
If the client binds an uniform and driver optimizes the uniform away, the
uniform location still exist -- this was the fix while back. The check is below
and above, (2).

     return false;
 
   if (!uniform_locations_[location_index].IsActive())

[Kimmo Kinnunen, 2016/01/21 12:36:32]

(2): This checks if the uniform has been optimized away by the driver.
This should not be executed by glUniform1i, though.
See the other (2).

I'll add an clarification, see the new patch.

     return false;
 
   UniformInfo* info = uniform_locations_[location_index].shader_variable();
 
   size_t element_index = GetArrayElementIndexFromFakeLocation(fake_location);
   if (static_cast<GLsizei>(element_index) >= info->size)
     return true;
   count = std::min(info->size - static_cast<GLsizei>(element_index), count);
   if (info->IsSampler() && count > 0) {
     for (GLsizei ii = 0; ii < count; ++ii) {
@@ skipping 956 matching lines @@
   DCHECK(program);
   program->ClearUniforms(&zero_);
 }
 
 int32_t ProgramManager::MakeFakeLocation(int32_t index, int32_t element) {
   return index + element * 0x10000;
 }
 
 }  // namespace gles2
 }  // namespace gpu