Infer sampler precision from pixel config

src/gpu/vk/GrVkProgramDesc.cpp

Index: src/gpu/vk/GrVkProgramDesc.cpp
diff --git a/src/gpu/vk/GrVkProgramDesc.cpp b/src/gpu/vk/GrVkProgramDesc.cpp
index 74e6bbb59d0c72b929cf30a7bf311150b7de6e66..cfd32ecdba71e123d9c136e7ed49521548f6cfd0 100644
--- a/src/gpu/vk/GrVkProgramDesc.cpp
+++ b/src/gpu/vk/GrVkProgramDesc.cpp
@@ -19,10 +19,17 @@
 
 #include "shaderc/shaderc.h"
 
+static uint8_t precision_key_nonzero_2_bits(GrShaderType shaderType, GrSLPrecision precision,
+                                            const GrShaderCaps& caps) {
+    return 1 + caps.effectiveFloatPrecision(shaderType, precision);
+
+    GR_STATIC_ASSERT(1 + kLast_GrSLPrecision < (1 << 2));
+}
+
 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;
@@ -32,6 +39,17 @@ static void add_texture_key(GrProcessorKeyBuilder* b, const GrProcessor& proc,
         const GrTextureAccess& access = proc.textureAccess(i);
         GrTexture* texture = access.getTexture();
         k16[i] = SkToU16(caps.configTextureSwizzle(texture->config()).asKey());
+        if (caps.usesPrecisionModifiers()) {
+            GrSLPrecision p = GrPixelConfigPrecision(texture->config());
+            if (access.getVisibility() & kFragment_GrShaderFlag) {
+                k16[i] |= precision_key_nonzero_2_bits(kFragment_GrShaderType, p, caps) << 12;
+            }
+            if (access.getVisibility() & (kVertex_GrShaderFlag | kGeometry_GrShaderFlag)) {
+                SkASSERT(precision_key_nonzero_2_bits(kVertex_GrShaderType, p, caps) ==
+                         precision_key_nonzero_2_bits(kGeometry_GrShaderType, p, caps));
+                k16[i] |= precision_key_nonzero_2_bits(kVertex_GrShaderType, p, caps) << 14;
+            }
+        }
     }
     // zero the last 16 bits if the number of textures is odd.
     if (numTextures & 0x1) {