Do div-by-zero check for all gpus in ellipse/rr effects.

src/gpu/GrOvalRenderer.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 "GrOvalRenderer.h"
 
 #include "GrEffect.h"
@@ skipping 212 matching lines @@
             builder->addVarying(kVec4f_GrSLType, "EllipseRadii", &vsRadiiName, &fsRadiiName);
             const SkString* attr1Name =
                 builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[1]);
             builder->vsCodeAppendf("\t%s = %s;\n", vsRadiiName, attr1Name->c_str());
 
             // for outer curve
             builder->fsCodeAppendf("\tvec2 scaledOffset = %s*%s.xy;\n", fsOffsetName, fsRadiiName);
             builder->fsCodeAppend("\tfloat test = dot(scaledOffset, scaledOffset) - 1.0;\n");
             builder->fsCodeAppendf("\tvec2 grad = 2.0*scaledOffset*%s.xy;\n", fsRadiiName);
             builder->fsCodeAppend("\tfloat grad_dot = dot(grad, grad);\n");
-            // we need to clamp the length^2 of the gradiant vector to a non-zero value, because
-            // on the Nexus 4 the undefined result of inversesqrt(0) drops out an entire tile
-            if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
-                builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");
-            }
+            // avoid calling inversesqrt on zero.
+            builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");
             builder->fsCodeAppend("\tfloat invlen = inversesqrt(grad_dot);\n");
             builder->fsCodeAppend("\tfloat edgeAlpha = clamp(0.5-test*invlen, 0.0, 1.0);\n");
 
             // for inner curve
             if (ellipseEffect.isStroked()) {
                 builder->fsCodeAppendf("\tscaledOffset = %s*%s.zw;\n", fsOffsetName, fsRadiiName);
                 builder->fsCodeAppend("\ttest = dot(scaledOffset, scaledOffset) - 1.0;\n");
                 builder->fsCodeAppendf("\tgrad = 2.0*scaledOffset*%s.zw;\n", fsRadiiName);
                 builder->fsCodeAppend("\tinvlen = inversesqrt(dot(grad, grad));\n");
                 builder->fsCodeAppend("\tedgeAlpha *= clamp(0.5+test*invlen, 0.0, 1.0);\n");
@@ skipping 124 matching lines @@
             // for outer curve
             builder->fsCodeAppendf("\tvec2 scaledOffset = %s.xy;\n", fsOffsetName0);
             builder->fsCodeAppend("\tfloat test = dot(scaledOffset, scaledOffset) - 1.0;\n");
             builder->fsCodeAppendf("\tvec2 duvdx = dFdx(%s);\n", fsOffsetName0);
             builder->fsCodeAppendf("\tvec2 duvdy = dFdy(%s);\n", fsOffsetName0);
             builder->fsCodeAppendf("\tvec2 grad = vec2(2.0*%s.x*duvdx.x + 2.0*%s.y*duvdx.y,\n"
                                    "\t                 2.0*%s.x*duvdy.x + 2.0*%s.y*duvdy.y);\n",
                                    fsOffsetName0, fsOffsetName0, fsOffsetName0, fsOffsetName0);
 
             builder->fsCodeAppend("\tfloat grad_dot = dot(grad, grad);\n");
-            // we need to clamp the length^2 of the gradiant vector to a non-zero value, because
-            // on the Nexus 4 the undefined result of inversesqrt(0) drops out an entire tile
-            if (builder->ctxInfo().caps()->dropsTileOnZeroDivide()) {
-                builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");
-            }
+            // avoid calling inversesqrt on zero.
+            builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");
             builder->fsCodeAppend("\tfloat invlen = inversesqrt(grad_dot);\n");
             if (kHairline == ellipseEffect.getMode()) {
                 // can probably do this with one step
                 builder->fsCodeAppend("\tfloat edgeAlpha = clamp(1.0-test*invlen, 0.0, 1.0);\n");
                 builder->fsCodeAppend("\tedgeAlpha *= clamp(1.0+test*invlen, 0.0, 1.0);\n");
             } else {
                 builder->fsCodeAppend("\tfloat edgeAlpha = clamp(0.5-test*invlen, 0.0, 1.0);\n");
             }
 
             // for inner curve
@@ skipping 743 matching lines @@
         }
 
         // drop out the middle quad if we're stroked
         int indexCnt = isStroked ? SK_ARRAY_COUNT(gRRectIndices)-6 : SK_ARRAY_COUNT(gRRectIndices);
         target->setIndexSourceToBuffer(indexBuffer);
         target->drawIndexed(kTriangles_GrPrimitiveType, 0, 0, 16, indexCnt, &bounds);
     }
 
     return true;
 }