Use new overflow aware integer operations.

A previous commit added inline functions that provide fast(er) and
correct overflow checks for signed integer math. Use them in a
significant portion of backend code.  There's more to touch in both
backend and frontend code, but these were the easily identifiable
cases.

The old overflow checks are noticeable in integer heavy workloads.

A secondary benefit is that getting rid of overflow checks that rely
on signed integer overflow wrapping around, will allow us to get rid
of -fwrapv in the future. Which in turn slows down other code.

Author: Andres Freund
Discussion: https://postgr.es/m/[email protected]

1 files changed, 5 insertions, 5 deletions

diff --git a/contrib/btree_gist/btree_int4.c b/contrib/btree_gist/btree_int4.c
index 35bb4424379..f2b6dec6607 100644
--- a/contrib/btree_gist/btree_int4.c
+++ b/contrib/btree_gist/btree_int4.c
@@ -5,6 +5,7 @@
 
 #include "btree_gist.h"
 #include "btree_utils_num.h"
+#include "common/int.h"
 
 typedef struct int32key
 {
@@ -99,15 +100,14 @@ int4_dist(PG_FUNCTION_ARGS)
 	int32		r;
 	int32		ra;
 
-	r = a - b;
-	ra = Abs(r);
-
-	/* Overflow check. */
-	if (ra < 0 || (!SAMESIGN(a, b) && !SAMESIGN(r, a)))
+	if (pg_sub_s32_overflow(a, b, &r) ||
+		r == INT32_MIN)
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("integer out of range")));
 
+	ra = Abs(r);
+
 	PG_RETURN_INT32(ra);
 }