On April 25, 2017 4:39:49 PM GMT+02:00, Jeff Law <l...@redhat.com> wrote:
>On 04/24/2017 05:25 AM, Richard Biener wrote:
>>
>> The following makes signed overflow undefined for all
>(non-)optimization
>> levels. The intent is to remove -fno-strict-overflow signed overflow
>> behavior as that is not a sensible option to the user (it ends up
>> with the worst of both -fwrapv and -fno-wrapv). The implementation
>> details need to be preserved for the forseeable future to not wreck
>> UBSAN with either associating (-fwrapv behavior) or optimizing
>> (-fno-wrapv behavior).
>>
>> The other choice would be to make -fwrapv the default for -O[01].
>>
>> A second patch in this series would unify -f[no-]wrapv, -f[no-]trapv
>> and -f[no-]strict-overflow with a
>> -fsigned-integer-overflow={undefined,wrapping,trapping[,sanitized]}
>> option, making conflicts amongst the options explicit (and reduce
>> the number of flag_ variables). 'sanitized' would essentially map
>> to todays flag_strict_overflow = 0. There's another sole user
>> of flag_strict_overflow, POINTER_TYPE_OVERFLOW_UNDEFINED - not sure
>> what to do about that, apart from exposing it as different flag
>> alltogether.
>>
>> Further patches in the series would remove -Wstrict-overflow (and
>> cleanup VRP for example).
>>
>> Anyway, most controversical part(?) below.
>>
>> Any comments on this particular patch (and the overall proposal)?
>>
>> Cleaning up the options is probably a no-brainer anyways.
>>
>> Thanks,
>> Richard.
>>
>> 2017-04-24 Richard Biener <rguent...@suse.de>
>>
>> * common.opt (fstrict-overflow): Enable by default.
>> * opts.c (default_options_table): Remove OPT_fstrict_overflow entry.
>Presumably when this work is complete -fno-strict-overflow will give
>some kind of reasonable error message to the user directing them to the
>
>new option that most likely does what they were looking for?
No, it will simply map to -fwrapv.
Richard.
>Jeff
