[Command buffer] Fix a bug for early return in blitFramebuffer

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 7894 matching lines @@
   }
 
   GLsizei read_buffer_samples = GetBoundFramebufferSamples(GL_READ_FRAMEBUFFER);
   if (read_buffer_samples > 0 &&
       (srcX0 != dstX0 || srcY0 != dstY0 || srcX1 != dstX1 || srcY1 != dstY1)) {
     LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, func_name,
         "src framebuffer is multisampled, but src/dst regions are different");
     return;
   }
 
+  // If color/depth/stencil buffer have no image, we can remove corresponding
+  // bitfield from mask and return early if mask equals to 0.
+  // But validations should be done against the original mask.
+  GLbitfield mask_blit = mask;
+
   // Detect that designated read/depth/stencil buffer in read framebuffer miss
   // image, and the corresponding buffers in draw framebuffer have image.
   bool read_framebuffer_miss_image = false;
 
   // Check whether read framebuffer and draw framebuffer have identical image
   // TODO(yunchao): consider doing something like CheckFramebufferStatus().
   // We cache the validation results, and if read_framebuffer doesn't change,
   // draw_framebuffer doesn't change, then use the cached status.
   enum FeedbackLoopState {
     FeedbackLoopTrue,
@@ skipping 27 matching lines @@
       }
     }
   } else {
     DCHECK(read_framebuffer && draw_framebuffer);
     if ((mask & GL_DEPTH_BUFFER_BIT) != 0) {
       const Framebuffer::Attachment* depth_buffer_read =
           read_framebuffer->GetAttachment(GL_DEPTH_ATTACHMENT);
       const Framebuffer::Attachment* depth_buffer_draw =
           draw_framebuffer->GetAttachment(GL_DEPTH_ATTACHMENT);
       if (!depth_buffer_draw || !depth_buffer_read) {
-        mask &= ~GL_DEPTH_BUFFER_BIT;
+        mask_blit &= ~GL_DEPTH_BUFFER_BIT;
         if (depth_buffer_draw) {
           read_framebuffer_miss_image = true;
         }
       } else if (depth_buffer_draw->IsSameAttachment(depth_buffer_read)) {
         is_feedback_loop = FeedbackLoopTrue;
       }
     }
     if ((mask & GL_STENCIL_BUFFER_BIT) != 0) {
       const Framebuffer::Attachment* stencil_buffer_read =
           read_framebuffer->GetAttachment(GL_STENCIL_ATTACHMENT);
       const Framebuffer::Attachment* stencil_buffer_draw =
           draw_framebuffer->GetAttachment(GL_STENCIL_ATTACHMENT);
       if (!stencil_buffer_draw || !stencil_buffer_read) {
-        mask &= ~GL_STENCIL_BUFFER_BIT;
+        mask_blit &= ~GL_STENCIL_BUFFER_BIT;
         if (stencil_buffer_draw) {
           read_framebuffer_miss_image = true;
         }
       } else if (stencil_buffer_draw->IsSameAttachment(stencil_buffer_read)) {
         is_feedback_loop = FeedbackLoopTrue;
       }
     }
-    if (!mask && !read_framebuffer_miss_image)
-      return;
   }
 
   GLenum src_internal_format = GetBoundReadFramebufferInternalFormat();
   GLenum src_type = GetBoundReadFramebufferTextureType();
 
   bool read_buffer_has_srgb =
       GetColorEncodingFromInternalFormat(src_internal_format) == GL_SRGB;
   bool draw_buffers_has_srgb = false;
   if ((mask & GL_COLOR_BUFFER_BIT) != 0) {
     bool is_src_signed_int =
@@ skipping 67 matching lines @@
        "The designated attachment point(s) in read framebuffer miss image");
     return;
   }
 
   if ((mask & (GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT)) != 0) {
     if (filter != GL_NEAREST) {
       LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, func_name,
                          "invalid filter for depth/stencil");
       return;
     }
-
-    if ((GetBoundFramebufferDepthFormat(GL_READ_FRAMEBUFFER) !=
-         GetBoundFramebufferDepthFormat(GL_DRAW_FRAMEBUFFER)) ||
-        (GetBoundFramebufferStencilFormat(GL_READ_FRAMEBUFFER) !=
-         GetBoundFramebufferStencilFormat(GL_DRAW_FRAMEBUFFER))) {
-      LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, func_name,
-                         "src and dst formats differ for depth/stencil");
-      return;
-    }
   }
 
+  mask = mask_blit;
+  if (!mask)
+    return;
+
+  if (((mask & GL_DEPTH_BUFFER_BIT) != 0 &&
+      (GetBoundFramebufferDepthFormat(GL_READ_FRAMEBUFFER) !=
+      GetBoundFramebufferDepthFormat(GL_DRAW_FRAMEBUFFER))) ||
+      ((mask & GL_STENCIL_BUFFER_BIT) != 0 &&
+      ((GetBoundFramebufferStencilFormat(GL_READ_FRAMEBUFFER) !=
+      GetBoundFramebufferStencilFormat(GL_DRAW_FRAMEBUFFER))))) {
+    LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, func_name,
+                       "src and dst formats differ for depth/stencil");
+    return;
+  }
+
+
   if (workarounds().adjust_src_dst_region_for_blitframebuffer) {
     gfx::Size read_size = GetBoundReadFramebufferSize();
     gfx::Rect src_bounds(0, 0, read_size.width(), read_size.height());
     GLint src_x = srcX1 > srcX0 ? srcX0 : srcX1;
     GLint src_y = srcY1 > srcY0 ? srcY0 : srcY1;
     base::CheckedNumeric<GLint> src_width_temp = srcX1;
     src_width_temp -= srcX0;
     base::CheckedNumeric<GLint> src_height_temp = srcY1;
     src_height_temp -= srcY0;
     GLuint src_width = 0, src_height = 0;
@@ skipping 10909 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