Indu Bhagat <indu.bha...@oracle.com> writes:
>>> [...]
>>> diff --git a/gcc/opts.cc b/gcc/opts.cc
>>> index 86c6691ecec4..00db662c32ef 100644
>>> --- a/gcc/opts.cc
>>> +++ b/gcc/opts.cc
>>> [...]
>>> @@ -2780,6 +2788,13 @@ common_handle_option (struct gcc_options *opts,
>>> SET_OPTION_IF_UNSET (opts, opts_set,
>>> param_hwasan_instrument_allocas, 0);
>>> }
>>> + /* Memtag sanitizer implies HWASAN but with tags always generated by
>>> the
>>> + hardware randomly. */
>>> + if (opts->x_flag_sanitize & SANITIZE_MEMTAG)
>>> + {
>>> + SET_OPTION_IF_UNSET (opts, opts_set,
>>> + param_hwasan_random_frame_tag, 1);
>>> + }
>>
>> Does this have any effect in practice? The default seems to be 1,
>> so I would expect this to be a nop. The pattern elsewhere in the
>> sanitiser code seems to be to use SET_OPTION_IF_UNSET only to turn
>> features off.
>>
>
> You're right. This can be removed.
>
> I recall now that what I wanted to achieve was to render users' usage of
> "--param hwasan-random-frame-tag=0" non-consequential when memtag
> sanitizer is in effect.
>
> Looks like I need to handle in finish_options (). Something like:
>
> if ((opts->x_flag_sanitize & SANITIZE_MEMTAG_STACK)
> && opts->x_param_hwasan_random_frame_tag == 0)
> {
> warning_at (loc, OPT_fsanitize_,
> "%<--param hwasan-random-frame-tag=0%> is not
> supported with"
> "%<-fsanitize=memtag-stack%>");
> opts->x_param_hwasan_random_frame_tag = 1;
> }
LGTM, although there's a missing space in the string continuation.
Richard
