Hi Mike,
Sorry for late reply (just back from vacation).
on 2024/2/8 03:58, Michael Meissner wrote:
> On Wed, Feb 07, 2024 at 05:21:10PM +0800, Kewen.Lin wrote:
>> on 2024/2/6 14:01, Michael Meissner wrote:
>> Sorry for the possible confusion here, the "tune_proc" that I referred to is
>> the variable in the above else branch:
>>
>> enum processor_type tune_proc = (TARGET_POWERPC64 ? PROCESSOR_DEFAULT64 :
>> PROCESSOR_DEFAULT);
>>
>> It's either PROCESSOR_DEFAULT64 or PROCESSOR_DEFAULT, so it doesn't have a
>> chance to be PROCESSOR_FUTURE, so the checking "tune_proc ==
>> PROCESSOR_FUTURE"
>> is useless.
>
> PROCESSOR_DEFAULT can be PROCESSOR_FUTURE if somebody configures GCC with
> --with-cpu=future. While in general it shouldn't occur, it is helpful to
> consider all of the corner cases.
But it sounds not true, I think you meant TARGET_CPU_DEFAULT instead?
On one local ppc64le machine I tried to configure with --with-cpu=power10,
I got {,OPTION_}TARGET_CPU_DEFAULT "power10" but PROCESSOR_DEFAULT is still
PROCESSOR_POWER7 (PROCESSOR_DEFAULT64 is PROCESSOR_POWER8). I think these
PROCESSOR_DEFAULT{,64} are defined by various headers:
$ grep -r "define PROCESSOR_DEFAULT" gcc/config/rs6000/
gcc/config/rs6000/aix71.h:#define PROCESSOR_DEFAULT PROCESSOR_POWER7
gcc/config/rs6000/aix71.h:#define PROCESSOR_DEFAULT64 PROCESSOR_POWER7
gcc/config/rs6000/aix72.h:#define PROCESSOR_DEFAULT PROCESSOR_POWER7
gcc/config/rs6000/aix72.h:#define PROCESSOR_DEFAULT64 PROCESSOR_POWER7
gcc/config/rs6000/aix73.h:#define PROCESSOR_DEFAULT PROCESSOR_POWER8
gcc/config/rs6000/aix73.h:#define PROCESSOR_DEFAULT64 PROCESSOR_POWER8
gcc/config/rs6000/darwin.h:#define PROCESSOR_DEFAULT PROCESSOR_PPC7400
gcc/config/rs6000/darwin.h:#define PROCESSOR_DEFAULT64 PROCESSOR_POWER4
gcc/config/rs6000/freebsd64.h:#define PROCESSOR_DEFAULT PROCESSOR_PPC7450
gcc/config/rs6000/freebsd64.h:#define PROCESSOR_DEFAULT64 PROCESSOR_POWER8
gcc/config/rs6000/linux64.h:#define PROCESSOR_DEFAULT PROCESSOR_POWER7
gcc/config/rs6000/linux64.h:#define PROCESSOR_DEFAULT64 PROCESSOR_POWER8
gcc/config/rs6000/rs6000.h:#define PROCESSOR_DEFAULT PROCESSOR_PPC603
gcc/config/rs6000/rs6000.h:#define PROCESSOR_DEFAULT64 PROCESSOR_RS64A
gcc/config/rs6000/vxworks.h:#define PROCESSOR_DEFAULT PROCESSOR_PPC604
, and they are unlikely to be updated later, no?
btw, the given --with-cpu=future will make cpu_index never negative so
...
else if (cpu_index >= 0)
rs6000_tune_index = tune_index = cpu_index;
else
...
so there is no chance to enter "else" arm, that is, that arm only takes
effect when no cpu/tune is given (neither -m{cpu,tune} nor --with-cpu=).
BR,
Kewen
