Changed pack alignment of GPU command buffer commands.

gpu/command_buffer/common/cmd_buffer_common.h

 // 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.
 
 // This file contains the common parts of command buffer formats.
 
 #ifndef GPU_COMMAND_BUFFER_COMMON_CMD_BUFFER_COMMON_H_
 #define GPU_COMMAND_BUFFER_COMMON_CMD_BUFFER_COMMON_H_
 
 #include <stddef.h>
@@ skipping 74 matching lines @@
   Uint32 value_uint32;
   Int32 value_int32;
   float value_float;
 };
 
 const size_t kCommandBufferEntrySize = 4;
 
 COMPILE_ASSERT(sizeof(CommandBufferEntry) == kCommandBufferEntrySize,
                Sizeof_CommandBufferEntry_is_not_4);
 
-// Make sure the compiler does not add extra padding to any of the command
-// structures.
-#pragma pack(push, 1)
+// Command buffer is 4 byte aligned.
+#pragma pack(push, 4)

[piman, 2014/02/03 22:30:49]

Do we even want anything at all, instead of just letting the compiler just use
whatever packing it likes best?

[vmiura, 2014/02/03 22:44:38]

The command buffer is 4 byte aligned, so this pack(4) is mainly here to make
sure any 8 byte aligned types in commands won't fault due to bad alignment on
any architecture.

Currently I think just QuerySync has a "uint64 result".

All other commands use just uint32/int32/float, so in theory pack(4) will be a
noop.

 
 // Gets the address of memory just after a structure in a typesafe way. This is
 // used for IMMEDIATE commands to get the address of the place to put the data.
 // Immediate command put their data direclty in the command buffer.
 // Parameters:
 //   cmd: Address of command.
 template <typename T>
 void* ImmediateDataAddress(T* cmd) {
   COMPILE_ASSERT(T::kArgFlags == cmd::kAtLeastN, Cmd_kArgFlags_not_kAtLeastN);
   return reinterpret_cast<char*>(cmd) + sizeof(*cmd);
@@ skipping 423 matching lines @@
                Offsetof_GetBucketData_shared_memory_offset_not_20);
 
 }  // namespace cmd
 
 #pragma pack(pop)
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_CMD_BUFFER_COMMON_H_