Revert 100494 - Revert "Revert 100453 - Revert "Revert 100384 - Fix bug in SimulateAttrib0.""

The bug was a unsigned->signed conversion issue. Clang truncates, gcc/vc overflow

TEST=unit tests
BUG=95625
TBR=apatrick@chromium.org

Review URL: http://codereview.chromium.org/7863007

TBR=gman@chromium.org
Review URL: http://codereview.chromium.org/7796015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@100498 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 42 insertions, 137 deletions

diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index b23e4ab..465bff8 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -1064,9 +1064,8 @@ class GLES2DecoderImpl : public base::SupportsWeakPtr<GLES2DecoderImpl>,
   // Checks if the current program and vertex attributes are valid for drawing.
   bool IsDrawValid(GLuint max_vertex_accessed);
 
-  // Returns true if successful, simulated will be true if attrib0 was
-  // simulated.
-  bool SimulateAttrib0(GLuint max_vertex_accessed, bool* simulated);
+  // Returns true if attrib0 was simulated.
+  bool SimulateAttrib0(GLuint max_vertex_accessed);
   void RestoreStateForSimulatedAttrib0();
 
   // Returns true if textures were set.
@@ -4263,48 +4262,30 @@ bool GLES2DecoderImpl::IsDrawValid(GLuint max_vertex_accessed) {
   return true;
 }
 
-bool GLES2DecoderImpl::SimulateAttrib0(
-    GLuint max_vertex_accessed, bool* simulated) {
-  DCHECK(simulated);
-  *simulated = false;
-
+bool GLES2DecoderImpl::SimulateAttrib0(GLuint max_vertex_accessed) {
   if (gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2)
-    return true;
+    return false;
 
   const VertexAttribManager::VertexAttribInfo* info =
       vertex_attrib_manager_.GetVertexAttribInfo(0);
   // If it's enabled or it's not used then we don't need to do anything.
   bool attrib_0_used = current_program_->GetAttribInfoByLocation(0) != NULL;
   if (info->enabled() && attrib_0_used) {
-    return true;
+    return false;
   }
 
-  // Make a buffer with a single repeated vec4 value enough to
-  // simulate the constant value that is supposed to be here.
-  // This is required to emulate GLES2 on GL.
   typedef VertexAttribManager::VertexAttribInfo::Vec4 Vec4;
 
-  GLuint num_vertices = max_vertex_accessed + 1;
-  GLuint size_needed = 0;
-
-  if (num_vertices == 0 ||
-      !SafeMultiply(num_vertices, static_cast<GLuint>(sizeof(Vec4)),
-                    &size_needed) ||
-      size_needed > 0x7FFFFFFFU) {
-    SetGLError(GL_OUT_OF_MEMORY, "glDrawXXX: Simulating attrib 0");
-    return false;
-  }
-
-  CopyRealGLErrorsToWrapper();
   glBindBuffer(GL_ARRAY_BUFFER, attrib_0_buffer_id_);
 
-  if (static_cast<GLsizei>(size_needed) > attrib_0_size_) {
+  // Make a buffer with a single repeated vec4 value enough to
+  // simulate the constant value that is supposed to be here.
+  // This is required to emulate GLES2 on GL.
+  GLsizei num_vertices = max_vertex_accessed + 1;
+  GLsizei size_needed = num_vertices * sizeof(Vec4);  // NOLINT
+  if (size_needed > attrib_0_size_) {
     glBufferData(GL_ARRAY_BUFFER, size_needed, NULL, GL_DYNAMIC_DRAW);
-    GLenum error = glGetError();
-    if (error != GL_NO_ERROR) {
-      SetGLError(GL_OUT_OF_MEMORY, "glDrawXXX: Simulating attrib 0");
-      return false;
-    }
+    // TODO(gman): check for error here?
     attrib_0_buffer_matches_value_ = false;
   }
   if (attrib_0_used &&
@@ -4322,7 +4303,6 @@ bool GLES2DecoderImpl::SimulateAttrib0(
 
   glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, NULL);
 
-  *simulated = true;
   return true;
 }
 
@@ -4357,13 +4337,8 @@ bool GLES2DecoderImpl::SimulateFixedAttribs(
   // tests so we just add to the buffer attrib used.
 
   // Compute the number of elements needed.
-  GLuint num_vertices = max_vertex_accessed + 1;
-  if (num_vertices == 0) {
-    SetGLError(GL_OUT_OF_MEMORY, "glDrawXXX: Simulating attrib 0");
-    return false;
-  }
-
-  GLuint elements_needed = 0;
+  int num_vertices = max_vertex_accessed + 1;
+  int elements_needed = 0;
   const VertexAttribManager::VertexAttribInfoList& infos =
       vertex_attrib_manager_.GetEnabledVertexAttribInfos();
   for (VertexAttribManager::VertexAttribInfoList::const_iterator it =
@@ -4374,9 +4349,10 @@ bool GLES2DecoderImpl::SimulateFixedAttribs(
     if (attrib_info &&
         info->CanAccess(max_vertex_accessed) &&
         info->type() == GL_FIXED) {
-      GLuint elements_used = 0;
-      if (!SafeMultiply(num_vertices,
-                        static_cast<GLuint>(info->size()), &elements_used) ||
+      int elements_used = 0;
+      if (!SafeMultiply(
+          static_cast<int>(num_vertices),
+          info->size(), &elements_used) ||
           !SafeAdd(elements_needed, elements_used, &elements_needed)) {
         SetGLError(GL_OUT_OF_MEMORY, "glDrawXXX: simulating GL_FIXED attribs");
         return false;
@@ -4384,24 +4360,17 @@ bool GLES2DecoderImpl::SimulateFixedAttribs(
     }
   }
 
-  const GLuint kSizeOfFloat = sizeof(float);  // NOLINT
-  GLuint size_needed = 0;
-  if (!SafeMultiply(elements_needed, kSizeOfFloat, &size_needed) ||
-      size_needed > 0x7FFFFFFFF) {
+  const int kSizeOfFloat = sizeof(float);  // NOLINT
+  int size_needed = 0;
+  if (!SafeMultiply(elements_needed, kSizeOfFloat, &size_needed)) {
     SetGLError(GL_OUT_OF_MEMORY, "glDrawXXX: simulating GL_FIXED attribs");
     return false;
   }
 
-  CopyRealGLErrorsToWrapper();
 
   glBindBuffer(GL_ARRAY_BUFFER, fixed_attrib_buffer_id_);
-  if (static_cast<GLsizei>(size_needed) > fixed_attrib_buffer_size_) {
+  if (size_needed > fixed_attrib_buffer_size_) {
     glBufferData(GL_ARRAY_BUFFER, size_needed, NULL, GL_DYNAMIC_DRAW);
-    GLenum error = glGetError();
-    if (error != GL_NO_ERROR) {
-      SetGLError(GL_OUT_OF_MEMORY, "glDrawXXX: simulating GL_FIXED attribs");
-      return false;
-    }
   }
 
   // Copy the elements and convert to float
@@ -4471,10 +4440,7 @@ error::Error GLES2DecoderImpl::HandleDrawArrays(
 
   GLuint max_vertex_accessed = first + count - 1;
   if (IsDrawValid(max_vertex_accessed)) {
-    bool simulated_attrib_0 = false;
-    if (!SimulateAttrib0(max_vertex_accessed, &simulated_attrib_0)) {
-      return error::kNoError;
-    }
+    bool simulated_attrib_0 = SimulateAttrib0(max_vertex_accessed);
     bool simulated_fixed_attribs = false;
     if (SimulateFixedAttribs(max_vertex_accessed, &simulated_fixed_attribs)) {
       bool textures_set = SetBlackTextureForNonRenderableTextures();
@@ -4545,10 +4511,7 @@ error::Error GLES2DecoderImpl::HandleDrawElements(
   }
 
   if (IsDrawValid(max_vertex_accessed)) {
-    bool simulated_attrib_0 = false;
-    if (!SimulateAttrib0(max_vertex_accessed, &simulated_attrib_0)) {
-      return error::kNoError;
-    }
+    bool simulated_attrib_0 = SimulateAttrib0(max_vertex_accessed);
     bool simulated_fixed_attribs = false;
     if (SimulateFixedAttribs(max_vertex_accessed, &simulated_fixed_attribs)) {
       bool textures_set = SetBlackTextureForNonRenderableTextures();
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc b/gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc
index c2c9e6b..d0c63bd 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_unittest.cc
@@ -55,17 +55,8 @@ class GLES2DecoderWithShaderTest : public GLES2DecoderWithShaderTestBase {
       : GLES2DecoderWithShaderTestBase() {
   }
 
-
-  void AddExpectationsForSimulatedAttrib0WithError(
-      GLsizei num_vertices, GLuint buffer_id, GLenum error) {
-    if (gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2) {
-      return;
-    }
-
-    EXPECT_CALL(*gl_, GetError())
-        .WillOnce(Return(GL_NO_ERROR))
-        .WillOnce(Return(error))
-        .RetiresOnSaturation();
+  void AddExpectationsForSimulatedAttrib0(
+      GLsizei num_vertices, GLuint buffer_id) {
     EXPECT_CALL(*gl_, BindBuffer(GL_ARRAY_BUFFER, kServiceAttrib0BufferId))
         .Times(1)
         .RetiresOnSaturation();
@@ -74,30 +65,22 @@ class GLES2DecoderWithShaderTest : public GLES2DecoderWithShaderTestBase {
                                  _, GL_DYNAMIC_DRAW))
         .Times(1)
         .RetiresOnSaturation();
-    if (error == GL_NO_ERROR) {
-      EXPECT_CALL(*gl_, BufferSubData(
-          GL_ARRAY_BUFFER, 0, num_vertices * sizeof(GLfloat) * 4, _))
-          .Times(1)
-          .RetiresOnSaturation();
-      EXPECT_CALL(*gl_, VertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, NULL))
-          .Times(1)
-          .RetiresOnSaturation();
-      EXPECT_CALL(*gl_, BindBuffer(GL_ARRAY_BUFFER, 0))
-          .Times(1)
-          .RetiresOnSaturation();
-      EXPECT_CALL(*gl_, VertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, NULL))
-          .Times(1)
-          .RetiresOnSaturation();
-      EXPECT_CALL(*gl_, BindBuffer(GL_ARRAY_BUFFER, buffer_id))
-          .Times(1)
-          .RetiresOnSaturation();
-    }
-  }
-
-  void AddExpectationsForSimulatedAttrib0(
-      GLsizei num_vertices, GLuint buffer_id) {
-    AddExpectationsForSimulatedAttrib0WithError(
-        num_vertices, buffer_id, GL_NO_ERROR);
+    EXPECT_CALL(*gl_, BufferSubData(
+        GL_ARRAY_BUFFER, 0, num_vertices * sizeof(GLfloat) * 4, _))
+        .Times(1)
+        .RetiresOnSaturation();
+    EXPECT_CALL(*gl_, VertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, NULL))
+        .Times(1)
+        .RetiresOnSaturation();
+    EXPECT_CALL(*gl_, BindBuffer(GL_ARRAY_BUFFER, 0))
+        .Times(1)
+        .RetiresOnSaturation();
+    EXPECT_CALL(*gl_, VertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, NULL))
+        .Times(1)
+        .RetiresOnSaturation();
+    EXPECT_CALL(*gl_, BindBuffer(GL_ARRAY_BUFFER, buffer_id))
+        .Times(1)
+        .RetiresOnSaturation();
   }
 };
 
@@ -142,47 +125,6 @@ TEST_F(GLES2DecoderWithShaderTest, DrawArraysNoAttributesSucceeds) {
   EXPECT_EQ(GL_NO_ERROR, GetGLError());
 }
 
-// Tests when the math overflows (0x40000000 * sizeof GLfloat)
-TEST_F(GLES2DecoderWithShaderTest, DrawArraysSimulatedAttrib0OverflowFails) {
-  const GLsizei kLargeCount = 0x40000000;
-  SetupTexture();
-  EXPECT_CALL(*gl_, DrawArrays(_, _, _))
-      .Times(0)
-      .RetiresOnSaturation();
-  DrawArrays cmd;
-  cmd.Init(GL_TRIANGLES, 0, kLargeCount);
-  EXPECT_EQ(error::kNoError, ExecuteCmd(cmd));
-  EXPECT_EQ(GL_OUT_OF_MEMORY, GetGLError());
-}
-
-// Tests when the math overflows (0x7FFFFFFF + 1 = 0x8000000 verts)
-TEST_F(GLES2DecoderWithShaderTest, DrawArraysSimulatedAttrib0PosToNegFails) {
-  const GLsizei kLargeCount = 0x7FFFFFFF;
-  SetupTexture();
-  EXPECT_CALL(*gl_, DrawArrays(_, _, _))
-      .Times(0)
-      .RetiresOnSaturation();
-  DrawArrays cmd;
-  cmd.Init(GL_TRIANGLES, 0, kLargeCount);
-  EXPECT_EQ(error::kNoError, ExecuteCmd(cmd));
-  EXPECT_EQ(GL_OUT_OF_MEMORY, GetGLError());
-}
-
-// Tests when the driver returns an error
-TEST_F(GLES2DecoderWithShaderTest, DrawArraysSimulatedAttrib0OOMFails) {
-  const GLsizei kFakeLargeCount = 0x1234;
-  SetupTexture();
-  AddExpectationsForSimulatedAttrib0WithError(
-      kFakeLargeCount, 0, GL_OUT_OF_MEMORY);
-  EXPECT_CALL(*gl_, DrawArrays(_, _, _))
-      .Times(0)
-      .RetiresOnSaturation();
-  DrawArrays cmd;
-  cmd.Init(GL_TRIANGLES, 0, kFakeLargeCount);
-  EXPECT_EQ(error::kNoError, ExecuteCmd(cmd));
-  EXPECT_EQ(GL_OUT_OF_MEMORY, GetGLError());
-}
-
 TEST_F(GLES2DecoderWithShaderTest, DrawArraysBadTextureUsesBlack) {
   DoBindTexture(GL_TEXTURE_2D, client_texture_id_, kServiceTextureId);
   // This is an NPOT texture. As the default filtering requires mips