diff --git a/src/gpu/GrProgramDesc.cpp b/src/gpu/GrProgramDesc.cpp
index ac7b8b9..c416e23 100644
--- a/src/gpu/GrProgramDesc.cpp
+++ b/src/gpu/GrProgramDesc.cpp
@@ -259,6 +259,10 @@
                                          programInfo.pipeline().numCoverageFragmentProcessors()) {
         return false;
     }
+    // If we knew the shader won't depend on origin, we could skip this (and use the same program
+    // for both origins). Instrumenting all fragment processors would be difficult and error prone.
+    header->fSurfaceOriginKey =
+        GrGLSLFragmentShaderBuilder::KeyForSurfaceOrigin(programInfo.origin());
     header->fProcessorFeatures = (uint8_t)processorFeatures;
     SkASSERT(header->processorFeatures() == processorFeatures);  // Ensure enough bits.
     header->fSnapVerticesToPixelCenters = programInfo.pipeline().snapVerticesToPixelCenters();
diff --git a/src/gpu/GrProgramDesc.h b/src/gpu/GrProgramDesc.h
index 75c763c..275b868 100644
--- a/src/gpu/GrProgramDesc.h
+++ b/src/gpu/GrProgramDesc.h
@@ -85,15 +85,9 @@
         return !(*this == other);
     }
 
-    void setSurfaceOriginKey(int key) {
-        KeyHeader* header = this->atOffset<KeyHeader, kHeaderOffset>();
-        header->fSurfaceOriginKey = key;
-    }
-
     struct KeyHeader {
-        bool hasSurfaceOriginKey() const {
-            return SkToBool(fSurfaceOriginKey);
-        }
+        SkDEBUGCODE(bool hasSurfaceOriginKey() const { return SkToBool(fSurfaceOriginKey); })
+
         GrProcessor::CustomFeatures processorFeatures() const {
             return (GrProcessor::CustomFeatures)fProcessorFeatures;
         }
diff --git a/src/gpu/gl/GrGLGpu.cpp b/src/gpu/gl/GrGLGpu.cpp
index bf2b81a..713358b 100644
--- a/src/gpu/gl/GrGLGpu.cpp
+++ b/src/gpu/gl/GrGLGpu.cpp
@@ -2172,9 +2172,7 @@
                    int meshCount) {
     this->handleDirtyContext();
 
-    if (meshCount == 0) {
-        return;
-    }
+    SkASSERT(meshCount); // guaranteed by GrOpsRenderPass::draw
 
     bool hasPoints = false;
     for (int i = 0; i < meshCount; ++i) {
diff --git a/src/gpu/gl/GrGLGpuProgramCache.cpp b/src/gpu/gl/GrGLGpuProgramCache.cpp
index 61ac321..3b683bf 100644
--- a/src/gpu/gl/GrGLGpuProgramCache.cpp
+++ b/src/gpu/gl/GrGLGpuProgramCache.cpp
@@ -51,17 +51,13 @@
                                                bool isPoints) {
 
 
-    // TODO: can this be unified between GL and Vk?
+    // TODO: can this be unified between GL, Vk and Mtl?
     // Get GrGLProgramDesc
     GrProgramDesc desc;
     if (!GrProgramDesc::Build(&desc, renderTarget, programInfo, isPoints, gpu)) {
         GrCapsDebugf(gpu->caps(), "Failed to gl program descriptor!\n");
         return nullptr;
     }
-    // If we knew the shader won't depend on origin, we could skip this (and use the same program
-    // for both origins). Instrumenting all fragment processors would be difficult and error prone.
-    desc.setSurfaceOriginKey(
-            GrGLSLFragmentShaderBuilder::KeyForSurfaceOrigin(programInfo.origin()));
 
     std::unique_ptr<Entry>* entry = fMap.find(desc);
     if (entry && !(*entry)->fProgram) {
diff --git a/src/gpu/mtl/GrMtlOpsRenderPass.mm b/src/gpu/mtl/GrMtlOpsRenderPass.mm
index 13d7fc8..19050ee 100644
--- a/src/gpu/mtl/GrMtlOpsRenderPass.mm
+++ b/src/gpu/mtl/GrMtlOpsRenderPass.mm
@@ -75,9 +75,8 @@
                                 const GrMesh meshes[],
                                 int meshCount,
                                 const SkRect& bounds) {
-    if (!meshCount) {
-        return;
-    }
+
+    SkASSERT(meshCount); // guaranteed by GrOpsRenderPass::draw
 
     GrPrimitiveType primitiveType = meshes[0].primitiveType();
     GrMtlPipelineState* pipelineState = this->prepareDrawState(programInfo, primitiveType);
diff --git a/src/gpu/mtl/GrMtlResourceProvider.mm b/src/gpu/mtl/GrMtlResourceProvider.mm
index 1074622..bc9b2ff 100644
--- a/src/gpu/mtl/GrMtlResourceProvider.mm
+++ b/src/gpu/mtl/GrMtlResourceProvider.mm
@@ -149,10 +149,6 @@
         GrCapsDebugf(fGpu->caps(), "Failed to build mtl program descriptor!\n");
         return nullptr;
     }
-    // If we knew the shader won't depend on origin, we could skip this (and use the same program
-    // for both origins). Instrumenting all fragment processors would be difficult and error prone.
-    desc.setSurfaceOriginKey(
-            GrGLSLFragmentShaderBuilder::KeyForSurfaceOrigin(programInfo.origin()));
 
     std::unique_ptr<Entry>* entry = fMap.find(desc);
     if (!entry) {
diff --git a/src/gpu/vk/GrVkOpsRenderPass.cpp b/src/gpu/vk/GrVkOpsRenderPass.cpp
index bd2c48e..864d82e 100644
--- a/src/gpu/vk/GrVkOpsRenderPass.cpp
+++ b/src/gpu/vk/GrVkOpsRenderPass.cpp
@@ -494,9 +494,8 @@
 void GrVkOpsRenderPass::onDraw(const GrProgramInfo& programInfo,
                                const GrMesh meshes[], int meshCount,
                                const SkRect& bounds) {
-    if (!meshCount) {
-        return;
-    }
+
+    SkASSERT(meshCount); // guaranteed by GrOpsRenderPass::draw
 
 #ifdef SK_DEBUG
     if (programInfo.hasDynamicPrimProcTextures()) {
diff --git a/src/gpu/vk/GrVkPipelineStateCache.cpp b/src/gpu/vk/GrVkPipelineStateCache.cpp
index fb4cfa8a..da6a69f 100644
--- a/src/gpu/vk/GrVkPipelineStateCache.cpp
+++ b/src/gpu/vk/GrVkPipelineStateCache.cpp
@@ -93,7 +93,7 @@
                       renderTarget->renderTargetPriv().numStencilBits());
     }
 
-    // TODO: can this be unified between Vulkan and GL?
+    // TODO: can this be unified between GL, Vk and Mtl?
     // Get GrVkProgramDesc
     GrVkPipelineStateBuilder::Desc desc;
     if (!GrVkPipelineStateBuilder::Desc::Build(&desc, renderTarget, programInfo, stencil,
@@ -101,10 +101,6 @@
         GrCapsDebugf(fGpu->caps(), "Failed to build vk program descriptor!\n");
         return nullptr;
     }
-    // If we knew the shader won't depend on origin, we could skip this (and use the same program
-    // for both origins). Instrumenting all fragment processors would be difficult and error prone.
-    desc.setSurfaceOriginKey(
-            GrGLSLFragmentShaderBuilder::KeyForSurfaceOrigin(programInfo.origin()));
 
     std::unique_ptr<Entry>* entry = fMap.find(desc);
     if (!entry) {