[PATCH] Fix INT_MIN % -1 overflow in int8mod().

Return 0 for INT_MIN % -1 (64-bit) instead of throwing an exception.
This patch complements commit f9ac414c that fixed int4mod().
---
src/backend/utils/adt/int8.c | 4 ++++
src/include/c.h | 7 +++++++
2 files changed, 11 insertions(+)

diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c
index 0e59956..9da651b 100644
--- a/src/backend/utils/adt/int8.c
+++ b/src/backend/utils/adt/int8.c
@@ -649,6 +649,10 @@ int8mod(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}

+ /* SELECT ((-9223372036854775808)::int8) % (-1); causes a floating point exception */
+ if (arg1 == INT64_MIN && arg2 == -1)
+ PG_RETURN_INT64(0);
+
/* No overflow is possible */

PG_RETURN_INT64(arg1 % arg2);
diff --git a/src/include/c.h b/src/include/c.h
index a6c0e6e..d20ba8c 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -294,6 +294,13 @@ typedef unsigned long long int uint64;
#define UINT64CONST(x) ((uint64) x)
#endif

+#ifndef INT64_MAX
+#define INT64_MAX INT64CONST(9223372036854775807)
+#endif
+
+#ifndef INT64_MIN
+#define INT64_MIN (-INT64_MAX-1)
+#endif

/* Select timestamp representation (float8 or int64) */
#ifdef USE_INTEGER_DATETIMES
--
1.7.10.4