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Improve handling of INT_MIN / -1 and related cases.

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Some platforms throw an exception for this division, rather than returning
a necessarily-overflowed result.  Since we were testing for overflow after
the fact, an exception isn't nice.  We can avoid the problem by treating
division by -1 as negation.

Add some regression tests so that we'll find out if any compilers try to
optimize away the overflow check conditions.

Back-patch of commit 1f7cb5c309.

Per discussion with Xi Wang, though this is different from the patch he
submitted.
This commit is contained in:
Tom Lane
2012-11-19 21:21:40 -05:00
parent fe838e5074
commit 4387cc9ab4
9 changed files with 233 additions and 83 deletions
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108
src/backend/utils/adt/int.c
View File

@@ -681,18 +681,6 @@ int4mul(PG_FUNCTION_ARGS)
int32 arg2 = PG_GETARG_INT32(1);
int32 result;
#ifdef WIN32
/*
* Win32 doesn't throw a catchable exception for SELECT -2147483648 *
* (-1); -- INT_MIN
*/
if (arg2 == -1 && arg1 == INT_MIN)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
#endif
result = arg1 * arg2;
/*
@@ -709,7 +697,8 @@ int4mul(PG_FUNCTION_ARGS)
if (!(arg1 >= (int32) SHRT_MIN && arg1 <= (int32) SHRT_MAX &&
arg2 >= (int32) SHRT_MIN && arg2 <= (int32) SHRT_MAX) &&
arg2 != 0 &&
(result / arg2 != arg1 || (arg2 == -1 && arg1 < 0 && result < 0)))
((arg2 == -1 && arg1 < 0 && result < 0) ||
result / arg2 != arg1))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
@@ -732,30 +721,27 @@ int4div(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}
#ifdef WIN32
/*
* Win32 doesn't throw a catchable exception for SELECT -2147483648 /
* (-1); -- INT_MIN
* INT_MIN / -1 is problematic, since the result can't be represented on a
* two's-complement machine. Some machines produce INT_MIN, some produce
* zero, some throw an exception. We can dodge the problem by recognizing
* that division by -1 is the same as negation.
*/
if (arg2 == -1 && arg1 == INT_MIN)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
#endif
if (arg2 == -1)
{
result = -arg1;
/* overflow check (needed for INT_MIN) */
if (arg1 != 0 && SAMESIGN(result, arg1))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
PG_RETURN_INT32(result);
}
/* No overflow is possible */
result = arg1 / arg2;
/*
* Overflow check. The only possible overflow case is for arg1 = INT_MIN,
* arg2 = -1, where the correct result is -INT_MIN, which can't be
* represented on a two's-complement machine. Most machines produce
* INT_MIN but it seems some produce zero.
*/
if (arg2 == -1 && arg1 < 0 && result <= 0)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
PG_RETURN_INT32(result);
}
@@ -877,18 +863,27 @@ int2div(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}
/*
* SHRT_MIN / -1 is problematic, since the result can't be represented on
* a two's-complement machine. Some machines produce SHRT_MIN, some
* produce zero, some throw an exception. We can dodge the problem by
* recognizing that division by -1 is the same as negation.
*/
if (arg2 == -1)
{
result = -arg1;
/* overflow check (needed for SHRT_MIN) */
if (arg1 != 0 && SAMESIGN(result, arg1))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("smallint out of range")));
PG_RETURN_INT16(result);
}
/* No overflow is possible */
result = arg1 / arg2;
/*
* Overflow check. The only possible overflow case is for arg1 =
* SHRT_MIN, arg2 = -1, where the correct result is -SHRT_MIN, which can't
* be represented on a two's-complement machine. Most machines produce
* SHRT_MIN but it seems some produce zero.
*/
if (arg2 == -1 && arg1 < 0 && result <= 0)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("smallint out of range")));
PG_RETURN_INT16(result);
}
@@ -1065,18 +1060,27 @@ int42div(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}
/*
* INT_MIN / -1 is problematic, since the result can't be represented on a
* two's-complement machine. Some machines produce INT_MIN, some produce
* zero, some throw an exception. We can dodge the problem by recognizing
* that division by -1 is the same as negation.
*/
if (arg2 == -1)
{
result = -arg1;
/* overflow check (needed for INT_MIN) */
if (arg1 != 0 && SAMESIGN(result, arg1))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
PG_RETURN_INT32(result);
}
/* No overflow is possible */
result = arg1 / arg2;
/*
* Overflow check. The only possible overflow case is for arg1 = INT_MIN,
* arg2 = -1, where the correct result is -INT_MIN, which can't be
* represented on a two's-complement machine. Most machines produce
* INT_MIN but it seems some produce zero.
*/
if (arg2 == -1 && arg1 < 0 && result <= 0)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
PG_RETURN_INT32(result);
}

90
src/backend/utils/adt/int8.c
View File

@@ -574,7 +574,8 @@ int8mul(PG_FUNCTION_ARGS)
if (arg1 != (int64) ((int32) arg1) || arg2 != (int64) ((int32) arg2))
{
if (arg2 != 0 &&
(result / arg2 != arg1 || (arg2 == -1 && arg1 < 0 && result < 0)))
((arg2 == -1 && arg1 < 0 && result < 0) ||
result / arg2 != arg1))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("bigint out of range")));
@@ -598,18 +599,27 @@ int8div(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}
/*
* INT64_MIN / -1 is problematic, since the result can't be represented on
* a two's-complement machine. Some machines produce INT64_MIN, some
* produce zero, some throw an exception. We can dodge the problem by
* recognizing that division by -1 is the same as negation.
*/
if (arg2 == -1)
{
result = -arg1;
/* overflow check (needed for INT64_MIN) */
if (arg1 != 0 && SAMESIGN(result, arg1))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("bigint out of range")));
PG_RETURN_INT64(result);
}
/* No overflow is possible */
result = arg1 / arg2;
/*
* Overflow check. The only possible overflow case is for arg1 =
* INT64_MIN, arg2 = -1, where the correct result is -INT64_MIN, which
* can't be represented on a two's-complement machine. Most machines
* produce INT64_MIN but it seems some produce zero.
*/
if (arg2 == -1 && arg1 < 0 && result <= 0)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("bigint out of range")));
PG_RETURN_INT64(result);
}
@@ -838,18 +848,27 @@ int84div(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}
/*
* INT64_MIN / -1 is problematic, since the result can't be represented on
* a two's-complement machine. Some machines produce INT64_MIN, some
* produce zero, some throw an exception. We can dodge the problem by
* recognizing that division by -1 is the same as negation.
*/
if (arg2 == -1)
{
result = -arg1;
/* overflow check (needed for INT64_MIN) */
if (arg1 != 0 && SAMESIGN(result, arg1))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("bigint out of range")));
PG_RETURN_INT64(result);
}
/* No overflow is possible */
result = arg1 / arg2;
/*
* Overflow check. The only possible overflow case is for arg1 =
* INT64_MIN, arg2 = -1, where the correct result is -INT64_MIN, which
* can't be represented on a two's-complement machine. Most machines
* produce INT64_MIN but it seems some produce zero.
*/
if (arg2 == -1 && arg1 < 0 && result <= 0)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("bigint out of range")));
PG_RETURN_INT64(result);
}
@@ -1026,18 +1045,27 @@ int82div(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}
/*
* INT64_MIN / -1 is problematic, since the result can't be represented on
* a two's-complement machine. Some machines produce INT64_MIN, some
* produce zero, some throw an exception. We can dodge the problem by
* recognizing that division by -1 is the same as negation.
*/
if (arg2 == -1)
{
result = -arg1;
/* overflow check (needed for INT64_MIN) */
if (arg1 != 0 && SAMESIGN(result, arg1))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("bigint out of range")));
PG_RETURN_INT64(result);
}
/* No overflow is possible */
result = arg1 / arg2;
/*
* Overflow check. The only possible overflow case is for arg1 =
* INT64_MIN, arg2 = -1, where the correct result is -INT64_MIN, which
* can't be represented on a two's-complement machine. Most machines
* produce INT64_MIN but it seems some produce zero.
*/
if (arg2 == -1 && arg1 < 0 && result <= 0)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("bigint out of range")));
PG_RETURN_INT64(result);
}