current program can be null in ES2/ES3 contexts.

gpu/command_buffer/service/gles2_cmd_decoder.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/gles2_cmd_decoder.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 3060 matching lines @@
     glGenTransformFeedbacks(1, &default_transform_feedback);
     state_.default_transform_feedback =
         transform_feedback_manager_->CreateTransformFeedback(
             0, default_transform_feedback);
     glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, default_transform_feedback);
     state_.bound_transform_feedback = state_.default_transform_feedback.get();
   }
   state_.indexed_uniform_buffer_bindings = new IndexedBufferBindingHost(
       group_->max_uniform_buffer_bindings(), needs_emulation);
 
-  state_.InitGenericAttribBaseType(group_->max_vertex_attribs());
-  state_.attrib_values.resize(group_->max_vertex_attribs());
+  state_.InitGenericAttribs(group_->max_vertex_attribs());
   vertex_array_manager_.reset(new VertexArrayManager());
 
   GLuint default_vertex_attrib_service_id = 0;
   if (features().native_vertex_array_object) {
     glGenVertexArraysOES(1, &default_vertex_attrib_service_id);
     glBindVertexArrayOES(default_vertex_attrib_service_id);
   }
 
   state_.default_vertex_attrib_manager =
       CreateVertexAttribManager(0, default_vertex_attrib_service_id, false);
@@ skipping 6037 matching lines @@
 void GLES2DecoderImpl::RestoreStateForSimulatedFixedAttribs() {
   // There's no need to call glVertexAttribPointer because we shadow all the
   // settings and passing GL_FIXED to it will not work.
   glBindBuffer(
       GL_ARRAY_BUFFER,
       state_.bound_array_buffer.get() ? state_.bound_array_buffer->service_id()
                                       : 0);
 }
 
 bool GLES2DecoderImpl::AttribsTypeMatch() {
-  for (uint32_t index = 0; index < group_->max_vertex_attribs(); index += 16) {
-    uint32_t shader_attrib_written_mask =
-        state_.current_program->vertex_input_type_written_mask(index);
-    uint32_t vao_attrib_enabled_mask =
-        state_.vertex_attrib_manager->attrib_enabled_mask(index);
-
-    uint32_t vertex_attrib_base_type_mask =
-        (~vao_attrib_enabled_mask &
-         state_.GetGenericVertexAttribBaseTypeMask(index)) |
-        (vao_attrib_enabled_mask &
-         state_.vertex_attrib_manager->attrib_base_type_mask(index));
-
-    if ((state_.current_program->vertex_input_base_type_mask(index)
-         & shader_attrib_written_mask) !=
-         (vertex_attrib_base_type_mask & shader_attrib_written_mask)) {
+  if (!state_.current_program.get())
+    return true;

[Zhenyao Mo, 2016/07/23 16:10:40]

This is actually the crash fix.  Everything else is cleanup.

[yunchao, 2016/07/24 04:52:13]

I see... 

+  const std::vector<uint32_t>& shader_attrib_active_mask =
+      state_.current_program->vertex_input_active_mask();
+  const std::vector<uint32_t>& shader_attrib_type_mask =
+      state_.current_program->vertex_input_base_type_mask();
+  const std::vector<uint32_t>& generic_vertex_attrib_type_mask =
+      state_.generic_attrib_base_type_mask();
+  const std::vector<uint32_t>& vertex_attrib_array_enabled_mask =
+      state_.vertex_attrib_manager->attrib_enabled_mask();
+  const std::vector<uint32_t>& vertex_attrib_array_type_mask =
+      state_.vertex_attrib_manager->attrib_base_type_mask();
+  DCHECK_EQ(shader_attrib_active_mask.size(),
+            shader_attrib_type_mask.size());
+  DCHECK_EQ(shader_attrib_active_mask.size(),
+            generic_vertex_attrib_type_mask.size());
+  DCHECK_EQ(shader_attrib_active_mask.size(),
+            vertex_attrib_array_enabled_mask.size());
+  DCHECK_EQ(shader_attrib_active_mask.size(),
+            vertex_attrib_array_type_mask.size());
+  for (size_t ii = 0; ii < shader_attrib_active_mask.size(); ++ii) {

[Zhenyao Mo, 2016/07/23 16:10:40]

This is a minor optimization. We can just query the entire masks altogether.

+    uint32_t vertex_attrib_source_type_mask =
+        (~vertex_attrib_array_enabled_mask[ii] &
+         generic_vertex_attrib_type_mask[ii]) |
+        (vertex_attrib_array_enabled_mask[ii] &
+         vertex_attrib_array_type_mask[ii]);
+    if ((shader_attrib_type_mask[ii] & shader_attrib_active_mask[ii]) !=
+        (vertex_attrib_source_type_mask & shader_attrib_active_mask[ii])) {
       return false;
     }
   }
   return true;
 }
 
 error::Error GLES2DecoderImpl::DoDrawArrays(
     const char* function_name,
     bool instanced,
     GLenum mode,
@@ skipping 8466 matching lines @@
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu