mem_alloc: Optimize allocation conflict checking

- When bufferImageGranularity == allocaAlignment the worst case is actually already evaluated
- When result offset and allocation size are already aligned, it is not possible for the 'page' to be shared

In both scenarios, a lot of work can be saved by simply not scanning suballocations. When dealing with many tiny allocations, this adds up a lot!

src/vk_mem_alloc.h

@@ -9656,7 +9656,7 @@ bool VmaBlockMetadata_Generic::CheckAllocation(
 
         // Check previous suballocations for BufferImageGranularity conflicts.
         // Make bigger alignment if necessary.
-        if(bufferImageGranularity > 1)
+        if(bufferImageGranularity > 1 && bufferImageGranularity != allocAlignment)
         {
             bool bufferImageGranularityConflict = false;
             VmaSuballocationList::const_iterator prevSuballocItem = suballocItem;
@@ -9740,7 +9740,7 @@ bool VmaBlockMetadata_Generic::CheckAllocation(
 
         // Check next suballocations for BufferImageGranularity conflicts.
         // If conflict exists, we must mark more allocations lost or fail.
-        if(bufferImageGranularity > 1)
+        if(allocSize % bufferImageGranularity || *pOffset % bufferImageGranularity)
         {
             VmaSuballocationList::const_iterator nextSuballocItem = lastSuballocItem;
             ++nextSuballocItem;
@@ -9799,7 +9799,7 @@ bool VmaBlockMetadata_Generic::CheckAllocation(
 
         // Check previous suballocations for BufferImageGranularity conflicts.
         // Make bigger alignment if necessary.
-        if(bufferImageGranularity > 1)
+        if(bufferImageGranularity > 1 && bufferImageGranularity != allocAlignment)
         {
             bool bufferImageGranularityConflict = false;
             VmaSuballocationList::const_iterator prevSuballocItem = suballocItem;
@@ -9839,7 +9839,7 @@ bool VmaBlockMetadata_Generic::CheckAllocation(
 
         // Check next suballocations for BufferImageGranularity conflicts.
         // If conflict exists, allocation cannot be made here.
-        if(bufferImageGranularity > 1)
+        if(allocSize % bufferImageGranularity || *pOffset % bufferImageGranularity)
         {
             VmaSuballocationList::const_iterator nextSuballocItem = suballocItem;
             ++nextSuballocItem;
@@ -11007,7 +11007,7 @@ bool VmaBlockMetadata_Linear::CreateAllocationRequest_UpperAddress(
 
     // Check next suballocations from 2nd for BufferImageGranularity conflicts.
     // Make bigger alignment if necessary.
-    if(bufferImageGranularity > 1 && !suballocations2nd.empty())
+    if(bufferImageGranularity > 1 && bufferImageGranularity != allocAlignment && !suballocations2nd.empty())
     {
         bool bufferImageGranularityConflict = false;
         for(size_t nextSuballocIndex = suballocations2nd.size(); nextSuballocIndex--; )
@@ -11112,7 +11112,7 @@ bool VmaBlockMetadata_Linear::CreateAllocationRequest_LowerAddress(
 
         // Check previous suballocations for BufferImageGranularity conflicts.
         // Make bigger alignment if necessary.
-        if(bufferImageGranularity > 1 && !suballocations1st.empty())
+        if(bufferImageGranularity > 1 && bufferImageGranularity != allocAlignment && !suballocations1st.empty())
         {
             bool bufferImageGranularityConflict = false;
             for(size_t prevSuballocIndex = suballocations1st.size(); prevSuballocIndex--; )
@@ -11144,7 +11144,7 @@ bool VmaBlockMetadata_Linear::CreateAllocationRequest_LowerAddress(
         {
             // Check next suballocations for BufferImageGranularity conflicts.
             // If conflict exists, allocation cannot be made here.
-            if(bufferImageGranularity > 1 && m_2ndVectorMode == SECOND_VECTOR_DOUBLE_STACK)
+            if((allocSize % bufferImageGranularity || resultOffset % bufferImageGranularity) && m_2ndVectorMode == SECOND_VECTOR_DOUBLE_STACK)
             {
                 for(size_t nextSuballocIndex = suballocations2nd.size(); nextSuballocIndex--; )
                 {
@@ -11202,7 +11202,7 @@ bool VmaBlockMetadata_Linear::CreateAllocationRequest_LowerAddress(
 
         // Check previous suballocations for BufferImageGranularity conflicts.
         // Make bigger alignment if necessary.
-        if(bufferImageGranularity > 1 && !suballocations2nd.empty())
+        if(bufferImageGranularity > 1 && bufferImageGranularity != allocAlignment && !suballocations2nd.empty())
         {
             bool bufferImageGranularityConflict = false;
             for(size_t prevSuballocIndex = suballocations2nd.size(); prevSuballocIndex--; )
@@ -11260,7 +11260,7 @@ bool VmaBlockMetadata_Linear::CreateAllocationRequest_LowerAddress(
 
             // Check next suballocations for BufferImageGranularity conflicts.
             // If conflict exists, we must mark more allocations lost or fail.
-            if(bufferImageGranularity > 1)
+            if(allocSize % bufferImageGranularity || resultOffset % bufferImageGranularity)
             {
                 while(index1st < suballocations1st.size())
                 {
@@ -11306,7 +11306,7 @@ bool VmaBlockMetadata_Linear::CreateAllocationRequest_LowerAddress(
         {
             // Check next suballocations for BufferImageGranularity conflicts.
             // If conflict exists, allocation cannot be made here.
-            if(bufferImageGranularity > 1)
+            if(allocSize % bufferImageGranularity || resultOffset % bufferImageGranularity)
             {
                 for(size_t nextSuballocIndex = index1st;
                     nextSuballocIndex < suballocations1st.size();