Optimize TilingData::TileBoundsWithBorder().

TileBoundsWithBorder called TileBounds(), then had a bunch of if
statements that undid all of the if statements in TileBounds. It's
more efficient just to do the computation directly, without the
function call and with far fewer conditionals; in infinite scrolling
test pages (http://groupcloned.com/test/) we see typically 100
calls WithBorder and 200 without border in the compositor on every
frame, as well as a few dozen calls of each on the renderer and
rasterizer threads.

This seems to provide a 1-2% speedup across most of cc_perftests
on N7-class hardware.

BUG=

Review URL: https://chromiumcodereview.appspot.com/15896002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@201942 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 28 insertions, 24 deletions

diff --git a/cc/base/tiling_data.cc b/cc/base/tiling_data.cc
index ba6aaa8..1045d89 100644
--- a/cc/base/tiling_data.cc
+++ b/cc/base/tiling_data.cc
@@ -146,14 +146,13 @@ gfx::Rect TilingData::TileBounds(int i, int j) const {
   int hi_x = max_texture_size_x * (i + 1) + border_texels_;
   if (i + 1 == num_tiles_x_)
     hi_x += border_texels_;
-  if (hi_x > total_size_x)
-    hi_x = total_size_x;
 
   int hi_y = max_texture_size_y * (j + 1) + border_texels_;
   if (j + 1 == num_tiles_y_)
     hi_y += border_texels_;
-  if (hi_y > total_size_y)
-    hi_y = total_size_y;
+
+  hi_x = std::min(hi_x, total_size_x);
+  hi_y = std::min(hi_y, total_size_y);
 
   int x = lo_x;
   int y = lo_y;
@@ -169,27 +168,32 @@ gfx::Rect TilingData::TileBounds(int i, int j) const {
 }
 
 gfx::Rect TilingData::TileBoundsWithBorder(int i, int j) const {
-  gfx::Rect bounds = TileBounds(i, j);
-
-  if (border_texels_) {
-    int x1 = bounds.x();
-    int x2 = bounds.right();
-    int y1 = bounds.y();
-    int y2 = bounds.bottom();
-
-    if (i > 0)
-      x1-= border_texels_;
-    if (i < (num_tiles_x_ - 1))
-      x2+= border_texels_;
-    if (j > 0)
-      y1-= border_texels_;
-    if (j < (num_tiles_y_ - 1))
-      y2+= border_texels_;
-
-    bounds = gfx::Rect(x1, y1, x2 - x1, y2 - y1);
-  }
+  AssertTile(i, j);
+  int max_texture_size_x = max_texture_size_.width() - 2 * border_texels_;
+  int max_texture_size_y = max_texture_size_.height() - 2 * border_texels_;
+  int total_size_x = total_size_.width();
+  int total_size_y = total_size_.height();
+
+  int lo_x = max_texture_size_x * i;
+  int lo_y = max_texture_size_y * j;
+
+  int hi_x = lo_x + max_texture_size_x + 2 * border_texels_;
+  int hi_y = lo_y + max_texture_size_y + 2 * border_texels_;
+
+  hi_x = std::min(hi_x, total_size_x);
+  hi_y = std::min(hi_y, total_size_y);
 
-  return bounds;
+  int x = lo_x;
+  int y = lo_y;
+  int width = hi_x - lo_x;
+  int height = hi_y - lo_y;
+  DCHECK_GE(x, 0);
+  DCHECK_GE(y, 0);
+  DCHECK_GE(width, 0);
+  DCHECK_GE(height, 0);
+  DCHECK_LE(x, total_size_.width());
+  DCHECK_LE(y, total_size_.height());
+  return gfx::Rect(x, y, width, height);
 }
 
 int TilingData::TilePositionX(int x_index) const {