Diego Biurrun <[email protected]> writes:

> On Thu, Aug 16, 2012 at 12:10:52AM +0100, Mans Rullgard wrote:
>> There used to be one test for Altivec intrinsics support and a
>> separate test to determine which of two possible syntaxes to use
>> for vector literals.  Since 2008, we only support the more common
>> of these so the split test no longer makes sense.
>> 
>> This combines the tests into one and also changes the hard error on
>> failure to a warning.  The test can reasonably fail if no --cpu flag
>> is provided (or is provided with an unknown CPU) and the compiler
>> default target does not support Altivec.  Aborting in this case is
>> probably over-reacting.
>> 
>> --- a/configure
>> +++ b/configure
>> @@ -2873,17 +2873,14 @@ elif enabled ppc; then
>>          check_cc <<EOF || disable altivec
>>  $inc_altivec_h
>>  int main(void) {
>> -    vector signed int v1, v2, v3;
>> -    v1 = vec_add(v2,v3);
>> +    vector signed int v1 = (vector signed int) { 0 };
>> +    vector signed int v2 = (vector signed int) { 1 };
>> +    v1 = vec_add(v1, v2);
>>      return 0;
>>  }
>>  EOF
>>  
>> -        # check if our compiler supports braces for vector declarations
>> -        check_cc <<EOF || die "You need a compiler that supports {} in 
>> AltiVec vector declarations."
>> -$inc_altivec_h
>> -int main (void) { (vector int) {1}; return 0; }
>> -EOF
>> +        enabled altivec || warn "Altivec disabled, possibly missing --cpu 
>> flag"
>>      fi
>
> Merging the two tests is OK, but you should also merge the two comments
> then.  IIRC this caused a lot of grief back in the day when the compiler
> did not support the syntax used in libavcodec.  It would fail after a
> long and expensive compile.  Erroring out early in configure was done
> on purpose.  I believe we should keep that behavior, since the compile
> error later on would be equally fatal.

I don't understand what you are trying to say.  It still checks for the
same things, but disables altivec with a warning rather than aborting if
the check fails.  There will be no error later.

-- 
Måns Rullgård
[email protected]
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