Make GrGLShaderBuilder::fragmentPosition() return a vec4, with 1.0 as the zw components when in the…

src/gpu/gl/GrGLShaderBuilder.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gl/GrGLShaderBuilder.h"
 #include "gl/GrGLProgram.h"
 #include "gl/GrGLUniformHandle.h"
@@ skipping 481 matching lines @@
             SkDEBUGFAIL("GrGLEffect asked for frag position but its generating GrEffect "
                          "did not request access.");
             return "";
         }
     }
     // We only declare "gl_FragCoord" when we're in the case where we want to use layout qualifiers
     // to reverse y. Otherwise it isn't necessary and whether the "in" qualifier appears in the
     // declaration varies in earlier GLSL specs. So it is simpler to omit it.
     if (fTopLeftFragPosRead) {
         fSetupFragPosition = true;
-        return "(gl_FragCoord.xy)";
+        return "gl_FragCoord";
     } else if (fGpu->glCaps().fragCoordConventionsSupport()) {
         if (!fSetupFragPosition) {
             SkAssertResult(this->enablePrivateFeature(kFragCoordConventions_GLSLPrivateFeature));
             fFSInputs.push_back().set(kVec4f_GrSLType,
                                       GrGLShaderVar::kIn_TypeModifier,
                                       "gl_FragCoord",
                                       GrGLShaderVar::kDefault_Precision,
                                       GrGLShaderVar::kUpperLeft_Origin);
             fSetupFragPosition = true;
         }
-        return "(gl_FragCoord.xy)";
+        return "gl_FragCoord";
     } else {
         static const char* kCoordName = "fragCoordYDown";
         if (!fSetupFragPosition) {
             // temporarily change the stage index because we're inserting non-stage code.
             CodeStage::AutoStageRestore csar(&fCodeStage, NULL);
 
             SkASSERT(!fOutput.fUniformHandles.fRTHeightUni.isValid());
             const char* rtHeightName;
 
             fOutput.fUniformHandles.fRTHeightUni =
                 this->addUniform(kFragment_Visibility, kFloat_GrSLType, "RTHeight", &rtHeightName);
 
-            this->fFSCode.prependf("\tvec2 %s = vec2(gl_FragCoord.x, %s - gl_FragCoord.y);\n",
-                                   kCoordName, rtHeightName);
+            // Using glFragCoord.zw for the last two components tickles an Adreno driver bug that
+            // causes programs to fail to link. Making this function return a vec2() didn't fix the
+            // problem but using 1.0 for the last two components does.
+            this->fFSCode.prependf("\tvec4 %s = vec4(gl_FragCoord.x, %s - gl_FragCoord.y, 1.0, "
+                                   "1.0);\n", kCoordName, rtHeightName);
             fSetupFragPosition = true;
         }
         SkASSERT(fOutput.fUniformHandles.fRTHeightUni.isValid());
         return kCoordName;
     }
 }
 
 void GrGLShaderBuilder::fsEmitFunction(GrSLType returnType,
                                        const char* name,
                                        int argCnt,
@@ skipping 555 matching lines @@
 
     GrGLPathTexGenProgramEffectsBuilder pathTexGenEffectsBuilder(this,
                                                                  effectCnt);
     this->INHERITED::createAndEmitEffects(&pathTexGenEffectsBuilder,
                                           effectStages,
                                           effectKeys,
                                           effectCnt,
                                           inOutFSColor);
     return pathTexGenEffectsBuilder.finish();
 }