commit ac1e4964e7816de1f4977b52fa5f2f372537468b
author Brian Osman <brianosman@google.com> Thu May 25 11:34:38 2017 -0400
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Thu May 25 16:15:07 2017 +0000
tree aebc6f877d48d956f72908b6cd27fd290502e156
parent 3fdd0bf2d90b1b82c1ac3aa982bdca600de7f4a8

Workaround Mali static analysis bug

Comment describes it: Unless we do something to confuse their optimizer,
they will (incorrectly) deduce that uniform opaque color (modulated only
by a texture fetch) is always going to remain opaque. Then they skip
inserting their shader based blending code, turning SrcOver into Src.

Doing a max against zero is enough to squelch the optimization.

Bug: skia:
Change-Id: I74676cebb0b0c8d121da868dd8a88050e0cfcc0d
Reviewed-on: https://skia-review.googlesource.com/17924
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp

diff --git a/src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp b/src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp
index f39fff2..d32766c 100644
--- a/src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp
+++ b/src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp
@@ -9,6 +9,7 @@
 
 #include "GrCoordTransform.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
+#include "glsl/GrGLSLProgramBuilder.h"
 #include "glsl/GrGLSLUniformHandler.h"
 #include "glsl/GrGLSLVertexShaderBuilder.h"
 
@@ -46,6 +47,9 @@
                                                "Color",
                                                &stagedLocalVarName);
     fragBuilder->codeAppendf("%s = %s;", outputName, stagedLocalVarName);
+    if (fragBuilder->getProgramBuilder()->shaderCaps()->mustObfuscateUniformColor()) {
+        fragBuilder->codeAppendf("%s = max(%s, vec4(0, 0, 0, 0));", outputName, outputName);
+    }
 }
 
 //////////////////////////////////////////////////////////////////////////////