gpu: Defer reads from default framebuffer when needed.

On some platforms, we want to unschedule after a swap until the ack, but the
DeferDraws mechanism allows us to delay the unschedule until we actually need to
access the back buffer. Up to now, only commands that *write* to the framebuffer
were considered, however we also need to consider *reads*. This fixes that.

BUG=None


Review URL: https://chromiumcodereview.appspot.com/11412262

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170435 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 71 insertions, 19 deletions

diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index ecd62a8..da321b2 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1184,6 +1184,8 @@ _FUNCTION_INFO = {
     'unit_test': False,
     'extension': True,
     'pepper_interface': 'FramebufferBlit',
+    'defer_reads': True,
+    'defer_draws': True,
   },
   'BufferData': {
     'type': 'Manual',
@@ -1203,8 +1205,8 @@ _FUNCTION_INFO = {
     'result': ['GLenum'],
   },
   'Clear': {
-    'type': 'Manual',
-    'cmd_args': 'GLbitfield mask'
+    'decoder_func': 'DoClear',
+    'defer_draws': True,
   },
   'ClearColor': {
     'type': 'StateSet',
@@ -1263,9 +1265,11 @@ _FUNCTION_INFO = {
   'CopyTexImage2D': {
     'decoder_func': 'DoCopyTexImage2D',
     'unit_test': False,
+    'defer_reads': True,
   },
   'CopyTexSubImage2D': {
     'decoder_func': 'DoCopyTexSubImage2D',
+    'defer_reads': True,
   },
   'CreateProgram': {
     'type': 'Create',
@@ -1396,12 +1400,14 @@ _FUNCTION_INFO = {
   'DrawArrays': {
     'type': 'Manual',
     'cmd_args': 'GLenumDrawMode mode, GLint first, GLsizei count',
+    'defer_draws': True,
   },
   'DrawElements': {
     'type': 'Manual',
     'cmd_args': 'GLenumDrawMode mode, GLsizei count, '
                 'GLenumIndexType type, GLuint index_offset',
-    'client_test': False
+    'client_test': False,
+    'defer_draws': True,
   },
   'Enable': {
     'decoder_func': 'DoEnable',
@@ -1794,6 +1800,7 @@ _FUNCTION_INFO = {
         'uint32 pixels_shm_id, uint32 pixels_shm_offset, '
         'uint32 result_shm_id, uint32 result_shm_offset',
     'result': ['uint32'],
+    'defer_reads': True,
   },
   'RegisterSharedIdsCHROMIUM': {
     'type': 'Custom',
@@ -2097,6 +2104,7 @@ _FUNCTION_INFO = {
     'extension': True,
     'unit_test': False,
     'pepper_interface': 'InstancedArrays',
+    'defer_draws': True,
   },
   'DrawElementsInstancedANGLE': {
     'type': 'Manual',
@@ -2106,6 +2114,7 @@ _FUNCTION_INFO = {
     'unit_test': False,
     'client_test': False,
     'pepper_interface': 'InstancedArrays',
+    'defer_draws': True,
   },
   'VertexAttribDivisorANGLE': {
     'type': 'Manual',
@@ -2567,6 +2576,7 @@ COMPILE_ASSERT(offsetof(%(cmd_name)s::Result, %(field_name)s) == %(offset)d,
         "error::Error GLES2DecoderImpl::Handle%s(\n" % func.name)
     file.Write(
         "    uint32 immediate_data_size, const gles2::%s& c) {\n" % func.name)
+    self.WriteHandlerDeferReadWrite(func, file);
     if len(func.GetOriginalArgs()) > 0:
       last_arg = func.GetLastOriginalArg()
       all_but_last_arg = func.GetOriginalArgs()[:-1]
@@ -2586,6 +2596,7 @@ COMPILE_ASSERT(offsetof(%(cmd_name)s::Result, %(field_name)s) == %(offset)d,
         "error::Error GLES2DecoderImpl::Handle%s(\n" % func.name)
     file.Write(
         "    uint32 immediate_data_size, const gles2::%s& c) {\n" % func.name)
+    self.WriteHandlerDeferReadWrite(func, file);
     last_arg = func.GetLastOriginalArg()
     all_but_last_arg = func.GetOriginalArgs()[:-1]
     for arg in all_but_last_arg:
@@ -2604,6 +2615,7 @@ COMPILE_ASSERT(offsetof(%(cmd_name)s::Result, %(field_name)s) == %(offset)d,
         "error::Error GLES2DecoderImpl::Handle%s(\n" % func.name)
     file.Write(
         "    uint32 immediate_data_size, const gles2::%s& c) {\n" % func.name)
+    self.WriteHandlerDeferReadWrite(func, file);
     last_arg = func.GetLastOriginalArg()
     all_but_last_arg = func.GetOriginalArgs()[:-1]
     for arg in all_but_last_arg:
@@ -2616,6 +2628,20 @@ COMPILE_ASSERT(offsetof(%(cmd_name)s::Result, %(field_name)s) == %(offset)d,
     file.Write("}\n")
     file.Write("\n")
 
+  def WriteHandlerDeferReadWrite(self, func, file):
+    """Writes the code to handle deferring reads or writes."""
+    defer_reads = func.GetInfo('defer_reads')
+    defer_draws = func.GetInfo('defer_draws')
+    conditions = []
+    if defer_draws:
+      conditions.append('ShouldDeferDraws()');
+    if defer_reads:
+      conditions.append('ShouldDeferReads()');
+    if not conditions:
+      return
+    file.Write("  if (%s)\n" % ' || '.join(conditions))
+    file.Write("    return error::kDeferCommandUntilLater;\n")
+
   def WriteValidUnitTest(self, func, file, test, extra = {}):
     """Writes a valid unit test."""
     if func.GetInfo('expectation') == False:
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 30389fa..bf24aa8 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -662,12 +662,6 @@ void GLES2Implementation::RestoreArrayBuffer(bool restore) {
   }
 }
 
-void GLES2Implementation::Clear(GLbitfield mask) {
-  GPU_CLIENT_SINGLE_THREAD_CHECK();
-  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glClear(" << mask << ")");
-  helper_->Clear(mask);
-}
-
 void GLES2Implementation::DrawElements(
     GLenum mode, GLsizei count, GLenum type, const void* indices) {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
diff --git a/gpu/command_buffer/client/gles2_implementation_impl_autogen.h b/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
index 1e8b056..8e452c2 100644
--- a/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
+++ b/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
@@ -117,6 +117,12 @@ GLenum GLES2Implementation::CheckFramebufferStatus(GLenum target) {
   return *result;
 }
 
+void GLES2Implementation::Clear(GLbitfield mask) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glClear(" << mask << ")");
+  helper_->Clear(mask);
+}
+
 void GLES2Implementation::ClearColor(
     GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha) {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 6e1f7bf..8914a84 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -1409,6 +1409,12 @@ class GLES2DecoderImpl : public GLES2Decoder {
            surface_->DeferDraws();
   }
 
+  bool ShouldDeferReads() {
+    return !offscreen_target_frame_buffer_.get() &&
+           state_.bound_read_framebuffer == NULL &&
+           surface_->DeferDraws();
+  }
+
   void ForceCompileShaderIfPending(ShaderManager::ShaderInfo* info);
 
   // Generate a member function prototype for each command in an automated and
@@ -3125,7 +3131,7 @@ bool GLES2DecoderImpl::ResizeOffscreenFrameBuffer(const gfx::Size& size) {
 
 error::Error GLES2DecoderImpl::HandleResizeCHROMIUM(
     uint32 immediate_data_size, const gles2::ResizeCHROMIUM& c) {
-  if (ShouldDeferDraws())
+  if (!offscreen_target_frame_buffer_.get() && surface_->DeferDraws())
     return error::kDeferCommandUntilLater;
 
   GLuint width = static_cast<GLuint>(c.width);
@@ -4238,8 +4244,7 @@ error::Error GLES2DecoderImpl::HandleRegisterSharedIdsCHROMIUM(
 }
 
 error::Error GLES2DecoderImpl::DoClear(GLbitfield mask) {
-  if (ShouldDeferDraws())
-    return error::kDeferCommandUntilLater;
+  DCHECK(!ShouldDeferDraws());
   if (CheckBoundFramebuffersValid("glClear")) {
     UNSHIPPED_TRACE_EVENT_INSTANT2(
         "test_gpu", "DoClear",
@@ -4251,12 +4256,6 @@ error::Error GLES2DecoderImpl::DoClear(GLbitfield mask) {
   return error::kNoError;
 }
 
-error::Error GLES2DecoderImpl::HandleClear(
-    uint32 immediate_data_size, const gles2::Clear& c) {
-  GLbitfield mask = static_cast<GLbitfield>(c.mask);
-  return DoClear(mask);
-}
-
 void GLES2DecoderImpl::DoFramebufferRenderbuffer(
     GLenum target, GLenum attachment, GLenum renderbuffertarget,
     GLuint client_renderbuffer_id) {
@@ -4505,6 +4504,7 @@ void GLES2DecoderImpl::DoBlitFramebufferEXT(
     GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
     GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1,
     GLbitfield mask, GLenum filter) {
+  DCHECK(!ShouldDeferReads() && !ShouldDeferDraws());
   if (!features().chromium_framebuffer_multisample) {
     SetGLError(GL_INVALID_OPERATION,
                "glBlitFramebufferEXT", "function not available");
@@ -6238,6 +6238,8 @@ error::Error GLES2DecoderImpl::HandleVertexAttribDivisorANGLE(
 
 error::Error GLES2DecoderImpl::HandleReadPixels(
     uint32 immediate_data_size, const gles2::ReadPixels& c) {
+  if (ShouldDeferReads())
+    return error::kDeferCommandUntilLater;
   GLint x = c.x;
   GLint y = c.y;
   GLsizei width = c.width;
@@ -7424,6 +7426,7 @@ void GLES2DecoderImpl::DoCopyTexImage2D(
     GLsizei width,
     GLsizei height,
     GLint border) {
+  DCHECK(!ShouldDeferReads());
   TextureManager::TextureInfo* info = GetTextureInfoForTarget(target);
   if (!info) {
     SetGLError(GL_INVALID_OPERATION,
@@ -7526,6 +7529,7 @@ void GLES2DecoderImpl::DoCopyTexSubImage2D(
     GLint y,
     GLsizei width,
     GLsizei height) {
+  DCHECK(!ShouldDeferReads());
   TextureManager::TextureInfo* info = GetTextureInfoForTarget(target);
   if (!info) {
     SetGLError(GL_INVALID_OPERATION,
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_autogen.h b/gpu/command_buffer/service/gles2_cmd_decoder_autogen.h
index 4a41a9f..722ee76 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_autogen.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_autogen.h
@@ -252,6 +252,15 @@ error::Error GLES2DecoderImpl::HandleCheckFramebufferStatus(
   return error::kNoError;
 }
 
+error::Error GLES2DecoderImpl::HandleClear(
+    uint32 immediate_data_size, const gles2::Clear& c) {
+  if (ShouldDeferDraws())
+    return error::kDeferCommandUntilLater;
+  GLbitfield mask = static_cast<GLbitfield>(c.mask);
+  DoClear(mask);
+  return error::kNoError;
+}
+
 error::Error GLES2DecoderImpl::HandleClearColor(
     uint32 immediate_data_size, const gles2::ClearColor& c) {
   GLclampf red = static_cast<GLclampf>(c.red);
@@ -402,6 +411,8 @@ error::Error GLES2DecoderImpl::HandleCompressedTexSubImage2DImmediate(
 
 error::Error GLES2DecoderImpl::HandleCopyTexImage2D(
     uint32 immediate_data_size, const gles2::CopyTexImage2D& c) {
+  if (ShouldDeferReads())
+    return error::kDeferCommandUntilLater;
   GLenum target = static_cast<GLenum>(c.target);
   GLint level = static_cast<GLint>(c.level);
   GLenum internalformat = static_cast<GLenum>(c.internalformat);
@@ -438,6 +449,8 @@ error::Error GLES2DecoderImpl::HandleCopyTexImage2D(
 
 error::Error GLES2DecoderImpl::HandleCopyTexSubImage2D(
     uint32 immediate_data_size, const gles2::CopyTexSubImage2D& c) {
+  if (ShouldDeferReads())
+    return error::kDeferCommandUntilLater;
   GLenum target = static_cast<GLenum>(c.target);
   GLint level = static_cast<GLint>(c.level);
   GLint xoffset = static_cast<GLint>(c.xoffset);
@@ -2635,6 +2648,8 @@ error::Error GLES2DecoderImpl::HandleViewport(
 
 error::Error GLES2DecoderImpl::HandleBlitFramebufferEXT(
     uint32 immediate_data_size, const gles2::BlitFramebufferEXT& c) {
+  if (ShouldDeferDraws() || ShouldDeferReads())
+    return error::kDeferCommandUntilLater;
   GLint srcX0 = static_cast<GLint>(c.srcX0);
   GLint srcY0 = static_cast<GLint>(c.srcY0);
   GLint srcX1 = static_cast<GLint>(c.srcX1);
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_1_autogen.h b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_1_autogen.h
index 7e817667..914ced8 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_1_autogen.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_1_autogen.h
@@ -308,8 +308,15 @@ TEST_F(GLES2DecoderTest1, CheckFramebufferStatusInvalidArgsBadSharedMemoryId) {
   cmd.Init(GL_FRAMEBUFFER, shared_memory_id_, kInvalidSharedMemoryOffset);
   EXPECT_EQ(error::kOutOfBounds, ExecuteCmd(cmd));
 }
-// TODO(gman): Clear
 
+TEST_F(GLES2DecoderTest1, ClearValidArgs) {
+  EXPECT_CALL(*gl_, Clear(1));
+  SpecializedSetup<Clear, 0>(true);
+  Clear cmd;
+  cmd.Init(1);
+  EXPECT_EQ(error::kNoError, ExecuteCmd(cmd));
+  EXPECT_EQ(GL_NO_ERROR, GetGLError());
+}
 
 TEST_F(GLES2DecoderTest1, ClearColorValidArgs) {
   EXPECT_CALL(*gl_, ClearColor(1, 2, 3, 4));