Hi Aldy,
This commit breaks the attached test case at -O2 on x86_64-linux-gnu and
loongarch64-linux-gnu :(.
The code is simplified from Glibc: the breakage causes two Glibc test
failures on loongarch64-linux-gnu.
Reverting the commit can fix the breakage.
On Wed, 2022-11-09 at 08:07 +0100, Aldy Hernandez via Gcc-patches wrote:
> Now that the generic parts of the binary operators have been
> abstracted, implementing MINUS_EXPR is a cinch.
>
> The op[12]_range entries will be submitted as a follow-up.
>
> gcc/ChangeLog:
>
> * range-op-float.cc (class foperator_minus): New.
> (floating_op_table::floating_op_table): Add MINUS_EXPR entry.
> ---
> gcc/range-op-float.cc | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
> index 7075c25442a..d52e971f84e 100644
> --- a/gcc/range-op-float.cc
> +++ b/gcc/range-op-float.cc
> @@ -1884,6 +1884,29 @@ class foperator_plus : public
> range_operator_float
> } fop_plus;
>
>
> +class foperator_minus : public range_operator_float
> +{
> + void rv_fold (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub, bool
> &maybe_nan,
> + tree type,
> + const REAL_VALUE_TYPE &lh_lb,
> + const REAL_VALUE_TYPE &lh_ub,
> + const REAL_VALUE_TYPE &rh_lb,
> + const REAL_VALUE_TYPE &rh_ub) const final override
> + {
> + frange_arithmetic (MINUS_EXPR, type, lb, lh_lb, rh_ub,
> dconstninf);
> + frange_arithmetic (MINUS_EXPR, type, ub, lh_ub, rh_lb,
> dconstinf);
> +
> + // [+INF] - [+INF] = NAN
> + if (real_isinf (&lh_ub, false) && real_isinf (&rh_ub, false))
> + maybe_nan = true;
> + // [-INF] - [-INF] = NAN
> + else if (real_isinf (&lh_lb, true) && real_isinf (&rh_lb, true))
> + maybe_nan = true;
> + else
> + maybe_nan = false;
> + }
> +} fop_minus;
> +
> // Instantiate a range_op_table for floating point operations.
> static floating_op_table global_floating_table;
>
> @@ -1917,6 +1940,7 @@ floating_op_table::floating_op_table ()
> set (ABS_EXPR, fop_abs);
> set (NEGATE_EXPR, fop_negate);
> set (PLUS_EXPR, fop_plus);
> + set (MINUS_EXPR, fop_minus);
> }
>
> // Return a pointer to the range_operator_float instance, if there is
--
Xi Ruoyao <xry...@xry111.site>
School of Aerospace Science and Technology, Xidian University
__attribute__((noipa,noinline))
int t(double a, double b)
{
double c = a - b;
if (!__builtin_isfinite(c)) {
if (__builtin_isnan(c)) {
if (!__builtin_isnan(a) && !__builtin_isnan(b))
return 1;
} else if (__builtin_isfinite(a) && __builtin_isfinite(b))
return 2;
} else if (c == 0 && a != b)
return 3;
return 4;
}
int main()
{
double a = __builtin_inf();
if (t(a, a) != 1)
__builtin_abort();
}
