Speculative fix for Tegra-based Androids: don't try to unpremultiply dstColor in-place; put it in a…

src/effects/SkArithmeticMode.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkArithmeticMode.h"
 #include "SkColorPriv.h"
 #include "SkFlattenableBuffers.h"
@@ skipping 310 matching lines @@
                                     EffectKey key,
                                     const char* outputColor,
                                     const char* inputColor,
                                     const TextureSamplerArray& samplers) {
     const char* dstColor = builder->dstColor();
     GrAssert(NULL != dstColor);
     fKUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
                                 kVec4f_GrSLType, "k");
     const char* kUni = builder->getUniformCStr(fKUni);
 
-    const char* srcColor = "srcColor";
-
     // We don't try to optimize for this case at all
     if (NULL == inputColor) {
-        builder->fsCodeAppendf("\t\tconst vec4 srcColor = %s;\n", GrGLSLOnesVecf(4));
+        builder->fsCodeAppendf("\t\tconst vec4 src = %s;\n", GrGLSLOnesVecf(4));
     } else {
-        builder->fsCodeAppendf("\t\tvec4 srcColor = %s;\n", inputColor);
-        builder->fsCodeAppendf("\t\tsrcColor.rgb = clamp(srcColor.rgb / srcColor.a, 0.0, 1.0);\n");
+        builder->fsCodeAppendf("\t\tvec4 src = %s;\n", inputColor);
+        builder->fsCodeAppendf("\t\tsrc.rgb = clamp(src.rgb / src.a, 0.0, 1.0);\n");
     }
 
-    builder->fsCodeAppendf("\t\t%s.rgb = clamp(%s.rgb / %s.a, 0.0, 1.0);\n", dstColor, dstColor, dstColor);
+    builder->fsCodeAppendf("\t\tvec4 dst = %s;\n", dstColor);
+    builder->fsCodeAppendf("\t\tdst.rgb = clamp(dst.rgb / dst.a, 0.0, 1.0);\n");
 
-    builder->fsCodeAppendf("\t\t%s = %s.x * %s * %s + %s.y * %s + %s.z * %s + %s.w;\n", outputColor, kUni, srcColor, dstColor, kUni, srcColor, kUni, dstColor, kUni);
+    builder->fsCodeAppendf("\t\t%s = %s.x * src * dst + %s.y * src + %s.z * dst + %s.w;\n", outputColor, kUni, kUni, kUni, kUni);
     builder->fsCodeAppendf("\t\t%s = clamp(%s, 0.0, 1.0);\n", outputColor, outputColor);
     builder->fsCodeAppendf("\t\t%s.rgb *= %s.a;\n", outputColor, outputColor);
 }
 
 void GrGLArithmeticEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
     const GrArithmeticEffect& arith = drawEffect.castEffect<GrArithmeticEffect>();
     uman.set4f(fKUni, arith.k1(), arith.k2(), arith.k3(), arith.k4());
 }
 
 GrGLEffect::EffectKey GrGLArithmeticEffect::GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
@@ skipping 26 matching lines @@
                                              SkScalarToFloat(fK[3]));
     }
     return true;
 }
 
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkArithmeticMode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkArithmeticMode_scalar)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END