- fixed FMemArena to always return 16 byte aligned pointers.

Unfortunately this turned out harder than expected because of FSharedStringArena making some strong assumptions about the underlying implementation.

src/memarena.cpp

@@ -46,6 +46,7 @@ struct FMemArena::Block
 	Block *NextBlock;
 	void *Limit;			// End of this block
 	void *Avail;			// Start of free space in this block
+	void *alignme;			// align to 16 bytes.
 
 	void Reset();
 	void *Alloc(size_t size);
@@ -94,7 +95,7 @@ FMemArena::~FMemArena()
 //
 //==========================================================================
 
-void *FMemArena::Alloc(size_t size)
+void *FMemArena::iAlloc(size_t size)
 {
 	Block *block;
 
@@ -110,6 +111,11 @@ void *FMemArena::Alloc(size_t size)
 	return block->Alloc(size);
 }
 
+void *FMemArena::Alloc(size_t size)
+{
+	return iAlloc((size + 15) & ~15);
+}
+
 //==========================================================================
 //
 // FMemArena :: FreeAll
@@ -316,7 +322,7 @@ FString *FSharedStringArena::Alloc(const FString &source)
 	strnode = FindString(source, source.Len(), hash);
 	if (strnode == NULL)
 	{
-		strnode = (Node *)FMemArena::Alloc(sizeof(Node));
+		strnode = (Node *)iAlloc(sizeof(Node));
 		::new(&strnode->String) FString(source);
 		strnode->Hash = hash;
 		hash %= countof(Buckets);
@@ -351,7 +357,7 @@ FString *FSharedStringArena::Alloc(const char *source, size_t strlen)
 	strnode = FindString(source, strlen, hash);
 	if (strnode == NULL)
 	{
-		strnode = (Node *)FMemArena::Alloc(sizeof(Node));
+		strnode = (Node *)iAlloc(sizeof(Node));
 		::new(&strnode->String) FString(source, strlen);
 		strnode->Hash = hash;
 		hash %= countof(Buckets);

src/memarena.h

@@ -54,6 +54,7 @@ protected:
 
 	Block *AddBlock(size_t size);
 	void FreeBlockChain(Block *&top);
+	void *iAlloc(size_t size);
 
 	Block *TopBlock;
 	Block *FreeBlocks;