[PATCH] rs6000: Better error messages for power8/9-vector builtins

[Bill Schmidt]

On 11/17/21 10:54 AM, Paul A. Clarke wrote:
> On Tue, Nov 16, 2021 at 11:12:35AM -0600, Bill Schmidt via Gcc-patches wrote:
>> Hi!  During a previous patch review, Segher asked that I provide better
>> messages when builtins are unavailable because they require both a minimum
>> CPU and the enablement of VSX instructions.  This patch does just that.
> ...
>> gcc/
>> 	* config/rs6000/rs6000-call.c (rs6000_invalid_new_builtin): Change
>> 	error messages for ENB_P8V and ENB_P9V.
>> ---
>>  gcc/config/rs6000/rs6000-call.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/gcc/config/rs6000/rs6000-call.c b/gcc/config/rs6000/rs6000-call.c
>> index 85fec80c6d7..035266eb001 100644
>> --- a/gcc/config/rs6000/rs6000-call.c
>> +++ b/gcc/config/rs6000/rs6000-call.c
>> @@ -11943,7 +11943,8 @@ rs6000_invalid_new_builtin (enum rs6000_gen_builtins fncode)
>>        error ("%qs requires the %qs option", name, "-mcpu=power8");
>>        break;
>>      case ENB_P8V:
>> -      error ("%qs requires the %qs option", name, "-mpower8-vector");
>> +      error ("%qs requires the %qs and %qs options", name, "-mcpu=power8",
>> +	     "-mvsx");
> "-mcpu=power8" itself enables "-mvsx", doesn't it?

Of course, but it can be disabled with -mno-vsx.  Then you get this error.
You won't get it unless you deliberately did something strange with the
compile options.

>
>>        break;
>>      case ENB_P9:
>>        error ("%qs requires the %qs option", name, "-mcpu=power9");
>> @@ -11953,7 +11954,8 @@ rs6000_invalid_new_builtin (enum rs6000_gen_builtins fncode)
>>  	     name, "-mcpu=power9", "-m64", "-mpowerpc64");
>>        break;
>>      case ENB_P9V:
>> -      error ("%qs requires the %qs option", name, "-mpower9-vector");
>> +      error ("%qs requires the %qs and %qs options", name, "-mcpu=power9",
>> +	     "-mvsx");
> Similarly, "-mcpu=power9" itself enables "-mvsx", doesn't it?
>
> Are you trying to also say "don't use -mno-vsx"?  If so, maybe s/and/with/
> would be slightly less confusing? This is going to be awkward unless it can
> be more precise, like two messages depending on actual context:
> - with "-mcpu=power8 -mno-vsx:  "...requires -mvsx".
> - without "-mcpu=power8":  "...requires -mcpu=power8".

This seems like a YMMV situation...I don't see the confusion myself.

Bill

>
> PC