On 4/22/21 10:04 AM, Richard Biener wrote:
> On Wed, Apr 21, 2021 at 3:08 PM Martin Liška <mliska@suse.cz> wrote:
>>
>> When -flto=jobserver is used and we cannot detect job server, then we can
>> still fallbackto -flto=N mode.
>>
>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>>
>> Ready to be installed?
> 
> I think this behavior needs to be documented - it falls back to a less
> conservative (possibly system overloading) mode - which IMHO is
> non-obvious and IMHO we shouldn't do.

Sure, I'm sending corresponding patch. Note that it's quite common mistake
that '+' is missing in Makefile rule. That was motivation for my change.

Martin

> 
> Richard.
> 
>> Thanks,
>> Martin
>>
>> gcc/ChangeLog:
>>
>>         * lto-wrapper.c (run_gcc): When -flto=jobserver is used, but the
>>         makeserver cannot be detected, then use -flto=N fallback.
>> ---
>>  gcc/lto-wrapper.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
>> index 03a5922f8ea..0b626d7c811 100644
>> --- a/gcc/lto-wrapper.c
>> +++ b/gcc/lto-wrapper.c
>> @@ -1585,8 +1585,9 @@ run_gcc (unsigned argc, char *argv[])
>>        if (jobserver && jobserver_error != NULL)
>>         {
>>           warning (0, jobserver_error);
>> -         parallel = 0;
>> +         /* Fall back to auto parallelism.  */
>>           jobserver = 0;
>> +         auto_parallel = 1;
>>         }
>>        else if (!jobserver && jobserver_error == NULL)
>>         {
>> --
>> 2.31.1
>>