Only look at gamut_transform if we wrote to it.

If we're already in sRGB gamut, we will not write to the 3x4 matrix,
but we still analyze it to see if we need clamping.  So we might
(harmlessly) re-clamp some already clamped colors unnecessarily.

Found by this Chromium MSAN bot.
Bug: chromium:789767
Change-Id: I5d76e59b541a03ee8efbd4352262b4f650e1ec01
Reviewed-on: https://skia-review.googlesource.com/79762
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 9 insertions, 9 deletions

diff --git a/src/effects/SkToSRGBColorFilter.cpp b/src/effects/SkToSRGBColorFilter.cpp
index 948c4d908b..41b54e1ecd 100644
--- a/src/effects/SkToSRGBColorFilter.cpp
+++ b/src/effects/SkToSRGBColorFilter.cpp
@@ -40,15 +40,15 @@ void SkToSRGBColorFilter::onAppendStages(SkRasterPipeline* p,
 
     // Step 2: Transform to sRGB gamut, without clamping.
     float* gamut_transform = alloc->makeArrayDefault<float>(12);
-    (void)append_gamut_transform_noclamp(p,
-                                         gamut_transform,
-                                         fSrcColorSpace.get(),
-                                         SkColorSpace::MakeSRGB().get());
-
-    bool needs_clamp_0, needs_clamp_1;
-    analyze_3x4_matrix(gamut_transform, &needs_clamp_0, &needs_clamp_1);
-    if (needs_clamp_0 || needs_clamp_1) {
-        p->set_clamped(false);
+    if (append_gamut_transform_noclamp(p,
+                                       gamut_transform,
+                                       fSrcColorSpace.get(),
+                                       SkColorSpace::MakeSRGB().get())) {
+        bool needs_clamp_0, needs_clamp_1;
+        analyze_3x4_matrix(gamut_transform, &needs_clamp_0, &needs_clamp_1);
+        if (needs_clamp_0 || needs_clamp_1) {
+            p->set_clamped(false);
+        }
     }
 
     // Step 3: Back to sRGB encoding.