Fix a bug where some bitmaps were being tinted wrong. It turns out

that when converting from RGB to HSL we were comparing doubles and
in on some CPUs, a register spill would cause us to do the conversion
wrong.

BUG=28243

Review URL: http://codereview.chromium.org/491036


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@34362 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 16 insertions, 3 deletions

diff --git a/app/gfx/color_utils.cc b/app/gfx/color_utils.cc
index 483e857..05b8bfa 100644
--- a/app/gfx/color_utils.cc
+++ b/app/gfx/color_utils.cc
@@ -95,11 +95,13 @@ void SkColorToHSL(SkColor c, HSL* hsl) {
     double dr = (((vmax - r) / 6.0) + (delta / 2.0)) / delta;
     double dg = (((vmax - g) / 6.0) + (delta / 2.0)) / delta;
     double db = (((vmax - b) / 6.0) + (delta / 2.0)) / delta;
-    if (r == vmax)
+    // We need to compare for the max value because comparing vmax to r,
+    // g or b can sometimes result in values overflowing registers.
+    if (r >= g && r >= b)
       hsl->h = db - dg;
-    else if (g == vmax)
+    else if (g >= r && g >= b)
       hsl->h = (1.0 / 3.0) + dr - db;
-    else  // (b == vmax)
+    else  // (b >= r && b >= g)
       hsl->h = (2.0 / 3.0) + dg - dr;
 
     if (hsl->h < 0.0)
diff --git a/app/gfx/color_utils_unittest.cc b/app/gfx/color_utils_unittest.cc
index 4e7f414..9ba7cb8 100644
--- a/app/gfx/color_utils_unittest.cc
+++ b/app/gfx/color_utils_unittest.cc
@@ -36,3 +36,14 @@ TEST(ColorUtils, HSLToSkColorWithAlpha) {
   EXPECT_EQ(SkColorGetB(red), SkColorGetB(result));
 }
 
+TEST(ColorUtils, ColorToHSLRegisterSpill) {
+  // In a opt build on Linux, this was causing a register spill on my laptop
+  // (Pentium M) when converting from SkColor to HSL.
+  SkColor input = SkColorSetARGB(255, 206, 154, 89);
+  color_utils::HSL hsl = { -1, -1, -1 };
+  SkColor result = color_utils::HSLShift(input, hsl);
+  EXPECT_EQ(255U, SkColorGetA(result));
+  EXPECT_EQ(206U, SkColorGetR(result));
+  EXPECT_EQ(153U, SkColorGetG(result));
+  EXPECT_EQ(88U, SkColorGetB(result));
+}