This is the mail archive of the
mailing list for the GCC project.
Re: [PATCH 4.8 v2, i386]: Make CCZ mode compatible with CCGOC and CCGO modes
On Tue, Feb 7, 2012 at 5:57 PM, Richard Henderson <firstname.lastname@example.org> wrote:
>>> Attached patch declares CCZmode compatible with CCGOC, CCGO and CCNO modes.
>> Actually, CCZ mode is not compatible with CCNO mode, since the later
>> only declares that overflow flag is not set. CCGOC and CCGO declare
>> garbage in overflow (and carry in case of CCGOC) flag, so implicitly
>> declare that CCZ flag is valid. Following this reasoning, CCZ mode
>> should be compatible with CCGOC and CCGO modes.
> We should probably fix this confusion by renaming the modes so that
> they're all positive:
> ?CCNO ? ? ? ? ?-> CCCSZ
> ?CCGC ? ? ? ? ?-> CCOSZ
> ?CCGOC ? ? ? ? -> CCSZ
No, no. Once you get the logic, it actually makes sense to name them
that way. Regarding your proposed change, CCNO does not say that CSZ
are all valid, it says that OF = 0, so the first line is wrong.