Force 8-alignment of memory blocks, as needed on

64-bit machines that require pointers to be aligned (e.g. IA64)

Python/pyarena.c

@@ -12,6 +12,11 @@
 */
 
 #define DEFAULT_BLOCK_SIZE 8192
+#define ALIGNMENT		8
+#define ALIGNMENT_SHIFT		3
+#define ALIGNMENT_MASK		(ALIGNMENT - 1)
+#define ROUNDUP(x)		(((x) + ALIGNMENT_MASK) & ~ALIGNMENT_MASK)
+
 typedef struct _block {
 	/* Total number of bytes owned by this block available to pass out.
 	 * Read-only after initialization.  The first such byte starts at
@@ -82,7 +87,8 @@ block_new(size_t size)
 	b->ab_size = size;
 	b->ab_mem = (void *)(b + 1);
 	b->ab_next = NULL;
-	b->ab_offset = 0;
+	b->ab_offset = ROUNDUP((Py_uintptr_t)(b->ab_mem)) - 
+	  (Py_uintptr_t)(b->ab_mem);
 	return b;
 }
 
@@ -100,6 +106,7 @@ block_alloc(block *b, size_t size)
 {
 	void *p;
 	assert(b);
+	size = ROUNDUP(size);
 	if (b->ab_offset + size > b->ab_size) {
 		/* If we need to allocate more memory than will fit in
 		   the default block, allocate a one-off block that is