* are most floating point cases in tree_call_nonnegative_warnv_p() wrong for HONOR_NANS?
@ 2022-11-13 15:56 Aldy Hernandez
2022-11-13 18:49 ` Aldy Hernandez
0 siblings, 1 reply; 2+ messages in thread
From: Aldy Hernandez @ 2022-11-13 15:56 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: gcc, amacleod
Based on discussions in the last few weeks, aren't most of the cases in
tree_call_nonnegative_warnv_p() wrong when honoring NANS?
For example:
CASE_CFN_ACOS:
CASE_CFN_ACOS_FN:
CASE_CFN_ACOSH:
CASE_CFN_ACOSH_FN:
...
...
/* Always true. */
return true;
But are we guaranteed a +NAN for any NAN input? I thought we were only
guaranteed the NAN sign for abs, copysign, assignment, etc? Similarly
for most other cases in this function.
Hmmm. I really think a good chunk of fold-const.cc should live in
range-ops. It seems we're duplicating a lot of functionality.
Similarly to bit-CCP as I've mentioned.
Aldy
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: are most floating point cases in tree_call_nonnegative_warnv_p() wrong for HONOR_NANS?
2022-11-13 15:56 are most floating point cases in tree_call_nonnegative_warnv_p() wrong for HONOR_NANS? Aldy Hernandez
@ 2022-11-13 18:49 ` Aldy Hernandez
0 siblings, 0 replies; 2+ messages in thread
From: Aldy Hernandez @ 2022-11-13 18:49 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: gcc, amacleod
I suppose most of the calls to tree_expr_nonnegative_p that apply to
floats in match.pd and tree-ssa-math-opts.cc are guarded by
!HONOR_NANS || tree_expr_nonnegative_p. Still feels kinda delicate...
Aldy
On Sun, Nov 13, 2022 at 4:56 PM Aldy Hernandez <aldyh@redhat.com> wrote:
>
> Based on discussions in the last few weeks, aren't most of the cases in
> tree_call_nonnegative_warnv_p() wrong when honoring NANS?
>
> For example:
> CASE_CFN_ACOS:
> CASE_CFN_ACOS_FN:
> CASE_CFN_ACOSH:
> CASE_CFN_ACOSH_FN:
> ...
> ...
> /* Always true. */
> return true;
>
> But are we guaranteed a +NAN for any NAN input? I thought we were only
> guaranteed the NAN sign for abs, copysign, assignment, etc? Similarly
> for most other cases in this function.
>
> Hmmm. I really think a good chunk of fold-const.cc should live in
> range-ops. It seems we're duplicating a lot of functionality.
> Similarly to bit-CCP as I've mentioned.
>
> Aldy
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