Fix an issue where map requests targetting buffers assigned memory blocks by VMA would not return correct ptr

Author: Dominik Witczak

include/misc/memalloc_backends/backend_oneshot.h

@@ -64,6 +64,7 @@ namespace Anvil
             bool     bake                            (Anvil::MemoryAllocator::Items&              in_items) final;
             VkResult map                             (void*                                       in_memory_object,
                                                       VkDeviceSize                                in_start_offset,
+                                                      VkDeviceSize                                in_memory_block_start_offset,
                                                       VkDeviceSize                                in_size,
                                                       void**                                      out_result_ptr) final;
             bool     supports_baking                 () const final;

include/misc/memalloc_backends/backend_vma.h

@@ -127,6 +127,7 @@ namespace Anvil
             bool     bake                            (Anvil::MemoryAllocator::Items&              in_items) final;
             VkResult map                             (void*                                       in_memory_object,
                                                       VkDeviceSize                                in_start_offset,
+                                                      VkDeviceSize                                in_memory_block_start_offset,
                                                       VkDeviceSize                                in_size,
                                                       void**                                      out_result_ptr);
             bool     supports_baking                 () const final;

include/misc/types_classes.h

@@ -36,6 +36,7 @@ namespace Anvil
 
         virtual VkResult map            (void*        in_memory_object,
                                          VkDeviceSize in_start_offset,
+                                         VkDeviceSize in_memory_block_start_offset,
                                          VkDeviceSize in_size,
                                          void**       out_result_ptr)   = 0;
         virtual bool     supports_baking() const                        = 0;

src/misc/memalloc_backends/backend_oneshot.cpp

@@ -418,9 +418,12 @@ bool Anvil::MemoryAllocatorBackends::OneShot::bake(Anvil::MemoryAllocator::Items
 
 VkResult Anvil::MemoryAllocatorBackends::OneShot::map(void*        in_memory_object,
                                                       VkDeviceSize in_start_offset,
+                                                      VkDeviceSize in_memory_block_start_offset,
                                                       VkDeviceSize in_size,
                                                       void**       out_result_ptr)
 {
+    ANVIL_REDUNDANT_VARIABLE(in_memory_block_start_offset);
+
     return Anvil::Vulkan::vkMapMemory(m_device_ptr->get_device_vk(),
                                       reinterpret_cast<VkDeviceMemory>(in_memory_object),
                                       in_start_offset,

src/misc/memalloc_backends/backend_vma.cpp

@@ -361,17 +361,26 @@ bool Anvil::MemoryAllocatorBackends::VMA::init()
 
 VkResult Anvil::MemoryAllocatorBackends::VMA::map(void*        in_memory_object,
                                                   VkDeviceSize in_start_offset,
+                                                  VkDeviceSize in_memory_block_start_offset,
                                                   VkDeviceSize in_size,
                                                   void**       out_result_ptr)
 {
+    VkResult result;
+    void*    result_ptr = nullptr;
+
     ANVIL_REDUNDANT_ARGUMENT(in_size);
     ANVIL_REDUNDANT_ARGUMENT(in_start_offset);
 
     anvil_assert(in_start_offset == 0);
 
-    return vmaMapMemory(m_vma_allocator_ptr->get_handle(),
-                        static_cast<VmaAllocation>(in_memory_object),
-                        out_result_ptr);
+    result = vmaMapMemory(m_vma_allocator_ptr->get_handle(),
+                          static_cast<VmaAllocation>(in_memory_object),
+                         &result_ptr);
+
+    result_ptr = reinterpret_cast<uint8_t*>(result_ptr) - in_memory_block_start_offset;
+
+    *out_result_ptr = result_ptr;
+    return result;
 }
 
 /** Please see header for specification */

src/wrappers/memory_block.cpp

@@ -682,8 +682,11 @@ bool Anvil::MemoryBlock::open_gpu_memory_access()
             {
                 result_vk = m_parent_memory_allocator_backend_ptr->map(m_backend_object,
                                                                        0, /* in_start_offset */
-                                                                       m_create_info_ptr->get_size(),
+                                                                       m_create_info_ptr->get_start_offset(),
+                                                                       m_create_info_ptr->get_size        (),
                                                                        static_cast<void**>(&m_gpu_data_ptr) );
+
+                m_gpu_data_ptr = reinterpret_cast<uint8_t*>(m_gpu_data_ptr);
             }
             else
             {