Infer sampler precision from pixel config

src/gpu/vk/GrVkProgramDesc.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "GrVkProgramDesc.h"
 
 //#include "GrVkProcessor.h"
 #include "GrProcessor.h"
 #include "GrPipeline.h"
 #include "GrRenderTargetPriv.h"
 #include "GrVkGpu.h"
 #include "GrVkUtil.h"
 #include "SkChecksum.h"
 #include "glsl/GrGLSLFragmentProcessor.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
 #include "glsl/GrGLSLCaps.h"
 
 #include "shaderc/shaderc.h"
 
 static void add_texture_key(GrProcessorKeyBuilder* b, const GrProcessor& proc,
                             const GrGLSLCaps& caps) {
     int numTextures = proc.numTextures();
-    // Need two bytes per key (swizzle and target).
+    // Need two bytes per key (swizzle, sampler type, and precision).
     int word32Count = (proc.numTextures() + 1) / 2;
     if (0 == word32Count) {
         return;
     }
     uint16_t* k16 = SkTCast<uint16_t*>(b->add32n(word32Count));
     for (int i = 0; i < numTextures; ++i) {
         const GrTextureAccess& access = proc.textureAccess(i);
         GrTexture* texture = access.getTexture();
-        k16[i] = SkToU16(caps.configTextureSwizzle(texture->config()).asKey());
+        k16[i] = SkToU16(caps.configTextureSwizzle(texture->config()).asKey() |
+                         (caps.samplerPrecision(texture->config(), access.getVisibility()) << 8));
     }
     // zero the last 16 bits if the number of textures is odd.
     if (numTextures & 0x1) {
         k16[numTextures] = 0;
     }
 }
 
 /**
 * A function which emits a meta key into the key builder.  This is required because shader code may
 * be dependent on properties of the effect that the effect itself doesn't use
@@ skipping 114 matching lines @@
     } else {
         header->fIgnoresCoverage = 0;
     }
 
     header->fSnapVerticesToPixelCenters = pipeline.snapVerticesToPixelCenters();
     header->fColorEffectCnt = pipeline.numColorFragmentProcessors();
     header->fCoverageEffectCnt = pipeline.numCoverageFragmentProcessors();
     vkDesc->finalize();
     return true;
 }