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Remove dependence on -fwrapv semantics in a few places.

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This commit attempts to update a few places, such as the money,
numeric, and timestamp types, to no longer rely on signed integer
wrapping for correctness.  This is intended to move us closer
towards removing -fwrapv, which may enable some compiler
optimizations.  However, there is presently no plan to actually
remove that compiler option in the near future.

Besides using some of the existing overflow-aware routines in
int.h, this commit introduces and makes use of some new ones.
Specifically, it adds functions that accept a signed integer and
return its absolute value as an unsigned integer with the same
width (e.g., pg_abs_s64()).  It also adds functions that accept an
unsigned integer, store the result of negating that integer in a
signed integer with the same width, and return whether the negation
overflowed (e.g., pg_neg_u64_overflow()).

Finally, this commit adds a couple of tests for timestamps near
POSTGRES_EPOCH_JDATE.

Author: Joseph Koshakow
Reviewed-by: Tom Lane, Heikki Linnakangas, Jian He
Discussion: https://postgr.es/m/CAAvxfHdBPOyEGS7s%2Bxf4iaW0-cgiq25jpYdWBqQqvLtLe_t6tw%40mail.gmail.com
This commit is contained in:
Nathan Bossart
2024-08-15 15:47:31 -05:00
parent ad89d71978
commit 9e9a2b7031
10 changed files with 189 additions and 65 deletions
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12
src/backend/utils/adt/cash.c
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@@ -387,6 +387,7 @@ Datum
cash_out(PG_FUNCTION_ARGS)
{
Cash value = PG_GETARG_CASH(0);
uint64 uvalue;
char *result;
char buf[128];
char *bufptr;
@@ -429,8 +430,6 @@ cash_out(PG_FUNCTION_ARGS)
if (value < 0)
{
/* make the amount positive for digit-reconstruction loop */
value = -value;
/* set up formatting data */
signsymbol = (*lconvert->negative_sign != '\0') ? lconvert->negative_sign : "-";
sign_posn = lconvert->n_sign_posn;
@@ -445,6 +444,9 @@ cash_out(PG_FUNCTION_ARGS)
sep_by_space = lconvert->p_sep_by_space;
}
/* make the amount positive for digit-reconstruction loop */
uvalue = pg_abs_s64(value);
/* we build the digits+decimal-point+sep string right-to-left in buf[] */
bufptr = buf + sizeof(buf) - 1;
*bufptr = '\0';
@@ -470,10 +472,10 @@ cash_out(PG_FUNCTION_ARGS)
memcpy(bufptr, ssymbol, strlen(ssymbol));
}
*(--bufptr) = ((uint64) value % 10) + '0';
value = ((uint64) value) / 10;
*(--bufptr) = (uvalue % 10) + '0';
uvalue = uvalue / 10;
digit_pos--;
} while (value || digit_pos >= 0);
} while (uvalue || digit_pos >= 0);
/*----------
* Now, attach currency symbol and sign symbol in the correct order.