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/20171024103954.ztmatprlglz3rwke@alap3.anarazel.de

5 files changed, 20 insertions, 22 deletions

diff --git a/contrib/btree_gist/btree_cash.c b/contrib/btree_gist/btree_cash.c
index 81131af4dc8..18f45f2750b 100644
--- a/contrib/btree_gist/btree_cash.c
+++ b/contrib/btree_gist/btree_cash.c
@@ -5,6 +5,7 @@
 
 #include "btree_gist.h"
 #include "btree_utils_num.h"
+#include "common/int.h"
 #include "utils/cash.h"
 
 typedef struct
@@ -99,15 +100,14 @@ cash_dist(PG_FUNCTION_ARGS)
 	Cash		r;
 	Cash		ra;
 
-	r = a - b;
-	ra = Abs(r);
-
-	/* Overflow check. */
-	if (ra < 0 || (!SAMESIGN(a, b) && !SAMESIGN(r, a)))
+	if (pg_sub_s64_overflow(a, b, &r) ||
+		r == INT64_MIN)
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("money out of range")));
 
+	ra = Abs(r);
+
 	PG_RETURN_CASH(ra);
 }
 
diff --git a/contrib/btree_gist/btree_int2.c b/contrib/btree_gist/btree_int2.c
index f343b8615f6..c2af4cd566d 100644
--- a/contrib/btree_gist/btree_int2.c
+++ b/contrib/btree_gist/btree_int2.c
@@ -5,6 +5,7 @@
 
 #include "btree_gist.h"
 #include "btree_utils_num.h"
+#include "common/int.h"
 
 typedef struct int16key
 {
@@ -98,15 +99,14 @@ int2_dist(PG_FUNCTION_ARGS)
 	int16		r;
 	int16		ra;
 
-	r = a - b;
-	ra = Abs(r);
-
-	/* Overflow check. */
-	if (ra < 0 || (!SAMESIGN(a, b) && !SAMESIGN(r, a)))
+	if (pg_sub_s16_overflow(a, b, &r) ||
+		r == INT16_MIN)
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("smallint out of range")));
 
+	ra = Abs(r);
+
 	PG_RETURN_INT16(ra);
 }
 
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);
 }
 
diff --git a/contrib/btree_gist/btree_int8.c b/contrib/btree_gist/btree_int8.c
index 91f2d032d10..16db0028b7a 100644
--- a/contrib/btree_gist/btree_int8.c
+++ b/contrib/btree_gist/btree_int8.c
@@ -5,6 +5,7 @@
 
 #include "btree_gist.h"
 #include "btree_utils_num.h"
+#include "common/int.h"
 
 typedef struct int64key
 {
@@ -99,15 +100,14 @@ int8_dist(PG_FUNCTION_ARGS)
 	int64		r;
 	int64		ra;
 
-	r = a - b;
-	ra = Abs(r);
-
-	/* Overflow check. */
-	if (ra < 0 || (!SAMESIGN(a, b) && !SAMESIGN(r, a)))
+	if (pg_sub_s64_overflow(a, b, &r) ||
+		r == INT64_MIN)
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("bigint out of range")));
 
+	ra = Abs(r);
+
 	PG_RETURN_INT64(ra);
 }
 
diff --git a/contrib/btree_gist/btree_utils_num.h b/contrib/btree_gist/btree_utils_num.h
index 17561fa9e4e..d7945f856c8 100644
--- a/contrib/btree_gist/btree_utils_num.h
+++ b/contrib/btree_gist/btree_utils_num.h
@@ -89,8 +89,6 @@ typedef struct
 
 #define GET_FLOAT_DISTANCE(t, arg1, arg2)	Abs( ((float8) *((const t *) (arg1))) - ((float8) *((const t *) (arg2))) )
 
-#define SAMESIGN(a,b)	(((a) < 0) == ((b) < 0))
-
 /*
  * check to see if a float4/8 val has underflowed or overflowed
  * borrowed from src/backend/utils/adt/float.c