Swizzle shader output and blend when using GL_RED to implement kAlpha_8_GrPixelConfig

src/gpu/gl/GrGLProgramDesc.cpp

Index: src/gpu/gl/GrGLProgramDesc.cpp
diff --git a/src/gpu/gl/GrGLProgramDesc.cpp b/src/gpu/gl/GrGLProgramDesc.cpp
index 45e01e7c84c2b13a5170bce2e09edaa8e2e3482c..91fc82b1230281a36abb8579611e8a056d3c5c2b 100644
--- a/src/gpu/gl/GrGLProgramDesc.cpp
+++ b/src/gpu/gl/GrGLProgramDesc.cpp
@@ -46,7 +46,7 @@ static void add_texture_key(GrProcessorKeyBuilder* b, const GrProcessor& proc,
  * function because it is hairy, though FPs do not have attribs, and GPs do not have transforms
  */
 static bool gen_meta_key(const GrProcessor& proc,
-                         const GrGLCaps& caps,
+                         const GrGLSLCaps& glslCaps,
                          uint32_t transformKey,
                          GrProcessorKeyBuilder* b) {
     size_t processorKeySize = b->size();
@@ -58,7 +58,7 @@ static bool gen_meta_key(const GrProcessor& proc,
         return false;
     }
 
-    add_texture_key(b, proc, *caps.glslCaps());
+    add_texture_key(b, proc, glslCaps);
 
     uint32_t* key = b->add32n(2);
     key[0] = (classID << 16) | SkToU32(processorKeySize);
@@ -76,17 +76,19 @@ static bool gen_frag_proc_and_meta_keys(const GrPrimitiveProcessor& primProc,
         }
     }
 
-    fp.getGLSLProcessorKey(*caps.glslCaps(), b);
+    const GrGLSLCaps& glslCaps = *caps.glslCaps();
+    fp.getGLSLProcessorKey(glslCaps, b);
 
-    //**** use glslCaps here?
-    return gen_meta_key(fp, caps, primProc.getTransformKey(fp.coordTransforms(),
-                                                           fp.numTransformsExclChildren()), b);
+    return gen_meta_key(fp, glslCaps, primProc.getTransformKey(fp.coordTransforms(),
+                                                               fp.numTransformsExclChildren()), b);
 }
 
 bool GrGLProgramDescBuilder::Build(GrProgramDesc* desc,
                                    const GrPrimitiveProcessor& primProc,
                                    const GrPipeline& pipeline,
                                    const GrGLGpu* gpu) {
+    const GrGLSLCaps& glslCaps = *gpu->glCaps().glslCaps();
+
     // The descriptor is used as a cache key. Thus when a field of the
     // descriptor will not affect program generation (because of the attribute
     // bindings in use or other descriptor field settings) it should be set
@@ -101,9 +103,8 @@ bool GrGLProgramDescBuilder::Build(GrProgramDesc* desc,
 
     GrProcessorKeyBuilder b(&glDesc->key());
 
-    primProc.getGLSLProcessorKey(*gpu->glCaps().glslCaps(), &b);
-    //**** use glslCaps here?
-    if (!gen_meta_key(primProc, gpu->glCaps(), 0, &b)) {
+    primProc.getGLSLProcessorKey(glslCaps, &b);
+    if (!gen_meta_key(primProc, glslCaps, 0, &b)) {
         glDesc->key().reset();
         return false;
     }
@@ -117,9 +118,8 @@ bool GrGLProgramDescBuilder::Build(GrProgramDesc* desc,
     }
 
     const GrXferProcessor& xp = pipeline.getXferProcessor();
-    xp.getGLSLProcessorKey(*gpu->glCaps().glslCaps(), &b);
-    //**** use glslCaps here?
-    if (!gen_meta_key(xp, gpu->glCaps(), 0, &b)) {
+    xp.getGLSLProcessorKey(glslCaps, &b);
+    if (!gen_meta_key(xp, glslCaps, 0, &b)) {
         glDesc->key().reset();
         return false;
     }
@@ -139,6 +139,9 @@ bool GrGLProgramDescBuilder::Build(GrProgramDesc* desc,
         header->fFragPosKey = 0;
     }
 
+    header->fOutputSwizzle =
+        glslCaps.configOutputSwizzle(pipeline.getRenderTarget()->config()).asKey();
+
     if (pipeline.ignoresCoverage()) {
         header->fIgnoresCoverage = 1;
     } else {