+/*
+ * MemSetAligned is the same as MemSet except it omits the test to see if
+ * "start" is word-aligned. This is okay to use if the caller knows a-priori
+ * that the pointer is suitably aligned (typically, because he just got it
+ * from palloc(), which always delivers a max-aligned pointer).
+ */
+#define MemSetAligned(start, val, len) \
+ do \
+ { \
+ long *_start = (long *) (start); \
+ int _val = (val); \
+ Size _len = (len); \
+\
+ if ((_len & LONG_ALIGN_MASK) == 0 && \
+ _val == 0 && \
+ _len <= MEMSET_LOOP_LIMIT && \
+ MEMSET_LOOP_LIMIT != 0) \
+ { \
+ long *_stop = (long *) ((char *) _start + _len); \
+ while (_start < _stop) \
+ *_start++ = 0; \
+ } \
+ else \
+ memset(_start, _val, _len); \
+ } while (0)
+
+
+/*
+ * MemSetTest/MemSetLoop are a variant version that allow all the tests in
+ * MemSet to be done at compile time in cases where "val" and "len" are
+ * constants *and* we know the "start" pointer must be word-aligned.
+ * If MemSetTest succeeds, then it is okay to use MemSetLoop, otherwise use
+ * MemSetAligned. Beware of multiple evaluations of the arguments when using
+ * this approach.
+ */
+#define MemSetTest(val, len) \
+ ( ((len) & LONG_ALIGN_MASK) == 0 && \
+ (len) <= MEMSET_LOOP_LIMIT && \
+ MEMSET_LOOP_LIMIT != 0 && \
+ (val) == 0 )
+
+#define MemSetLoop(start, val, len) \
+ do \
+ { \
+ long * _start = (long *) (start); \
+ long * _stop = (long *) ((char *) _start + (Size) (len)); \
+ \
+ while (_start < _stop) \
+ *_start++ = 0; \
+ } while (0)