Re: [PATCH] testsuite: update requires for powerpc/float128-cmp2-runnable.c

[guojiufu <guojiufu@linux.ibm.com>]

Hi Kewen,

Thanks a lot for your very helpful comments!

On 2023-04-10 17:26, Kewen.Lin wrote:
> Hi Jeff,
> 
> on 2023/4/10 10:09, Jiufu Guo via Gcc-patches wrote:
>> Hi,
>> 
>> In this test case (float128-cmp2-runnable.c), the instruction
>> xscmpexpqp is used to support a few builtins e.g.
>> __builtin_vsx_scalar_cmp_exp_qp_eq on _Float128.
>> This instruction handles the whole 128bits of the vector, and
>> it is guarded by [ieee128-hw].
> 
> The instruction xscmpexpqp is guarded with TARGET_P9_VECTOR,
> 
> (define_insn "*xscmpexpqp"
>   [(set (match_operand:CCFP 0 "cc_reg_operand" "=y")
> 	(compare:CCFP
> 	 (unspec:IEEE128 [(match_operand:IEEE128 1 "altivec_register_operand" 
> "v")
> 		          (match_operand:IEEE128 2 "altivec_register_operand" "v")]
> 	  UNSPEC_VSX_SCMPEXPQP)
> 	 (match_operand:SI 3 "zero_constant" "j")))]
>   "TARGET_P9_VECTOR"
>   "xscmpexpqp %0,%1,%2"
>   [(set_attr "type" "fpcompare")])
> 
> [ieee128-hw] is used for guarding those bifs, so the above
> statement doesn't quite match the fact.
> 

Agree, I'm wondering if P9_VECTOR is perfect here, even if it indicates 
the ISA
which contains xscmpexpqp. Let me have more checks.

> PR108758 said this case doesn't fail with gcc-10 and gcc-11,
> I wonder why it changes from gcc-12?  The above define_insn
> shows the underlying insns for these bifs just requires the
> condition power9-vector.  Could you have a further check?
> Thanks.

Thanks for raising this concern.
The behavior to check about bif on FLOAT128_HW and emit an error message 
for
requirements on quad-precision is added in gcc12. This is why gcc12 
fails to
compile the case on -m32.

Before gcc12, altivec_resolve_overloaded_builtin will return the 
overloaded
result directly, and does not check more about the result function.

> 
> btw, please add a PR marker for PR108758.

Sure,  thanks for catching this!


BR,
Jeff (Jiufu)

> 
> BR,
> Kewen
> 
>> So, we may update the testcase to require ppc_float128_hw.
>> 
>> Tested on ppc64 both BE and LE.
>> Is this ok for trunk?
>> 
>> BR,
>> Jeff (Jiufu)
>> 
>> gcc/testsuite/ChangeLog:
>> 
>> 	* gcc.target/powerpc/float128-cmp2-runnable.c: Update requires.
>> 
>> ---
>>  gcc/testsuite/gcc.target/powerpc/float128-cmp2-runnable.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/gcc/testsuite/gcc.target/powerpc/float128-cmp2-runnable.c 
>> b/gcc/testsuite/gcc.target/powerpc/float128-cmp2-runnable.c
>> index d376a3ca68e..91287c0fb7a 100644
>> --- a/gcc/testsuite/gcc.target/powerpc/float128-cmp2-runnable.c
>> +++ b/gcc/testsuite/gcc.target/powerpc/float128-cmp2-runnable.c
>> @@ -1,5 +1,5 @@
>>  /* { dg-do run } */
>> -/* { dg-require-effective-target ppc_float128_sw } */
>> +/* { dg-require-effective-target ppc_float128_hw } */
>>  /* { dg-require-effective-target p9vector_hw } */
>>  /* { dg-options "-O2 -mdejagnu-cpu=power9 " } */
>>