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Use new overflow aware integer operations.

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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
This commit is contained in:
Andres Freund
2017-12-12 16:32:31 -08:00
parent 4d6ad31257
commit 101c7ee3ee
14 changed files with 220 additions and 542 deletions
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13
src/backend/utils/adt/varlena.c
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@ -21,6 +21,7 @@
#include "access/tuptoaster.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_type.h"
#include "common/int.h"
#include "common/md5.h"
#include "lib/hyperloglog.h"
#include "libpq/pqformat.h"
@ -1047,8 +1048,7 @@ text_overlay(text *t1, text *t2, int sp, int sl)
ereport(ERROR,
(errcode(ERRCODE_SUBSTRING_ERROR),
errmsg("negative substring length not allowed")));
sp_pl_sl = sp + sl;
if (sp_pl_sl <= sl)
if (pg_add_s32_overflow(sp, sl, &sp_pl_sl))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
@ -2950,8 +2950,7 @@ bytea_overlay(bytea *t1, bytea *t2, int sp, int sl)
ereport(ERROR,
(errcode(ERRCODE_SUBSTRING_ERROR),
errmsg("negative substring length not allowed")));
sp_pl_sl = sp + sl;
if (sp_pl_sl <= sl)
if (pg_add_s32_overflow(sp, sl, &sp_pl_sl))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("integer out of range")));
@ -5279,13 +5278,13 @@ text_format_parse_digits(const char **ptr, const char *end_ptr, int *value)
while (*cp >= '0' && *cp <= '9')
{
int newval = val * 10 + (*cp - '0');
int8 digit = (*cp - '0');
if (newval / 10 != val) /* overflow? */
if (unlikely(pg_mul_s32_overflow(val, 10, &val)) ||
unlikely(pg_add_s32_overflow(val, digit, &val)))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("number is out of range")));
val = newval;
ADVANCE_PARSE_POINTER(cp, end_ptr);
found = true;
}