Add check for highp support in Conic effect

src/gpu/effects/GrBezierEffect.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 "GrBezierEffect.h"
 
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
@@ skipping 93 matching lines @@
     // emit transforms with position
     this->emitTransforms(vertBuilder,
                          varyingHandler,
                          uniformHandler,
                          gpArgs->fPositionVar,
                          gp.inPosition()->fName,
                          gp.localMatrix(),
                          args.fTransformsIn,
                          args.fTransformsOut);
 
-    GrGLSLShaderVar edgeAlpha("edgeAlpha", kFloat_GrSLType, 0, kHigh_GrSLPrecision);
-    GrGLSLShaderVar dklmdx("dklmdx", kVec3f_GrSLType, 0, kHigh_GrSLPrecision);
-    GrGLSLShaderVar dklmdy("dklmdy", kVec3f_GrSLType, 0, kHigh_GrSLPrecision);
-    GrGLSLShaderVar dfdx("dfdx", kFloat_GrSLType, 0, kHigh_GrSLPrecision);
-    GrGLSLShaderVar dfdy("dfdy", kFloat_GrSLType, 0, kHigh_GrSLPrecision);
-    GrGLSLShaderVar gF("gF", kVec2f_GrSLType, 0, kHigh_GrSLPrecision);
-    GrGLSLShaderVar gFM("gFM", kFloat_GrSLType, 0, kHigh_GrSLPrecision);
-    GrGLSLShaderVar func("func", kFloat_GrSLType, 0, kHigh_GrSLPrecision);
+    // TODO: this precision check should actually be a check on the number of bits
+    // high and medium provide and the selection of the lowest level that suffices.
+    // Additionally we should assert that the upstream code only lets us get here if
+    // either high or medium provides the required number of bits.
+    GrSLPrecision precision = kHigh_GrSLPrecision;
+    const GrShaderCaps::PrecisionInfo& highP = args.fGLSLCaps->getFloatShaderPrecisionInfo(
+                                                             kFragment_GrShaderType,
+                                                             kHigh_GrSLPrecision);
+    if (!highP.supported()) {
+        precision = kMedium_GrSLPrecision;
+    }
+
+    GrGLSLShaderVar edgeAlpha("edgeAlpha", kFloat_GrSLType, 0, precision);
+    GrGLSLShaderVar dklmdx("dklmdx", kVec3f_GrSLType, 0, precision);
+    GrGLSLShaderVar dklmdy("dklmdy", kVec3f_GrSLType, 0, precision);
+    GrGLSLShaderVar dfdx("dfdx", kFloat_GrSLType, 0, precision);
+    GrGLSLShaderVar dfdy("dfdy", kFloat_GrSLType, 0, precision);
+    GrGLSLShaderVar gF("gF", kVec2f_GrSLType, 0, precision);
+    GrGLSLShaderVar gFM("gFM", kFloat_GrSLType, 0, precision);
+    GrGLSLShaderVar func("func", kFloat_GrSLType, 0, precision);
 
     fragBuilder->declAppend(edgeAlpha);
     fragBuilder->declAppend(dklmdx);
     fragBuilder->declAppend(dklmdy);
     fragBuilder->declAppend(dfdx);
     fragBuilder->declAppend(dfdy);
     fragBuilder->declAppend(gF);
     fragBuilder->declAppend(gFM);
     fragBuilder->declAppend(func);
 
@@ skipping 579 matching lines @@
     do {
         GrPrimitiveEdgeType edgeType =
                 static_cast<GrPrimitiveEdgeType>(
                         d->fRandom->nextULessThan(kGrProcessorEdgeTypeCnt));
         gp = GrCubicEffect::Create(GrRandomColor(d->fRandom),
                                    GrTest::TestMatrix(d->fRandom), edgeType, *d->fCaps);
     } while (nullptr == gp);
     return gp;
 }