Add offset to memory allocations

src/gpu/vk/GrVkBuffer.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrVkBuffer_DEFINED
 #define GrVkBuffer_DEFINED
 
 #include "GrVkResource.h"
 #include "vk/GrVkDefines.h"
 
 class GrVkGpu;
 
 /**
  * This class serves as the base of GrVk*Buffer classes. It was written to avoid code
  * duplication in those classes.
  */
 class GrVkBuffer : public SkNoncopyable {
 public:
     ~GrVkBuffer() {
         // either release or abandon should have been called by the owner of this object.
         SkASSERT(!fResource);
     }
 
     VkBuffer       buffer() const { return fResource->fBuffer; }
     VkDeviceMemory alloc() const { return fResource->fAlloc; }
+    VkDeviceSize   offset() const { return fResource->fOffset; }
     const GrVkResource* resource() const { return fResource; }
     size_t         size() const { return fDesc.fSizeInBytes; }
 
     void addMemoryBarrier(const GrVkGpu* gpu,
                           VkAccessFlags srcAccessMask,
                           VkAccessFlags dstAccessMask,
                           VkPipelineStageFlags srcStageMask,
                           VkPipelineStageFlags dstStageMask,
                           bool byRegion) const;
 
     enum Type {
         kVertex_Type,
         kIndex_Type,
         kUniform_Type,
         kCopyRead_Type,
         kCopyWrite_Type,
     };
 
 protected:
     struct Desc {
         size_t      fSizeInBytes;
         Type        fType;         // vertex buffer, index buffer, etc.
         bool        fDynamic;
     };
 
     class Resource : public GrVkResource {
     public:
-        Resource(VkBuffer buf, VkDeviceMemory alloc) : INHERITED(), fBuffer(buf), fAlloc(alloc) {}
+        Resource(VkBuffer buf, VkDeviceMemory alloc, VkDeviceSize offset) 
+            : INHERITED(), fBuffer(buf), fAlloc(alloc), fOffset(offset) {}
 
-        VkBuffer fBuffer;
+        VkBuffer       fBuffer;
         VkDeviceMemory fAlloc;

[egdaniel, 2016/05/31 13:22:14]

I haven't though deeply into this, but do you think there would be any advantage
to having like a GrVkDeviceMemory class that would wrap the VkDeviceMemory and
offsets so the images/buffers don't need to know about them?

[jvanverth1, 2016/05/31 22:05:57]

I added a GrVkAlloc struct to GrVkTypes that wraps both the VkDeviceMemory and
the offset. I considered using a class, but it looked like the members would end
up being effectively public, so went for the simpler approach.

+        VkDeviceSize   fOffset;
+
     private:
         void freeGPUData(const GrVkGpu* gpu) const;
 
         typedef GrVkResource INHERITED;
     };
 
     // convenience routine for raw buffer creation
     static const Resource* Create(const GrVkGpu* gpu,
                                   const Desc& descriptor);
 
@@ skipping 16 matching lines @@
     bool vkIsMapped() const;
 
     Desc                    fDesc;
     const Resource*         fResource;
     void*                   fMapPtr;
 
     typedef SkNoncopyable INHERITED;
 };
 
 #endif