Re: [PATCH] adjust vectorization expectations for ppc costmodel 76b

["Kewen.Lin" <linkw@linux.ibm.com>]

on 2024/4/29 14:28, Alexandre Oliva wrote:
> On Apr 28, 2024, "Kewen.Lin" <linkw@linux.ibm.com> wrote:
> 
>> Nit: Maybe add a prefix "testsuite: ".
> 
> ACK
> 
>>>
>>> From: Kewen Lin <linkw@linux.ibm.com>
> 
>> Thanks, you can just drop this.  :)
> 
> I've turned it into Co-Authored-By, since you insist.
> 
> But unfortunately with the patch it still fails when testing for
> -mcpu=power7 on ppc64le-linux-gnu: it does vectorize the loop with 13
> iterations.  We need 16 iterations, as in an earlier version of this
> test, for it to pass for -mcpu=power7, but then it doesn't pass for
> -mcpu=power6.
> 
> It looks like we're going to have to adjust the expectations.
> 

I had a look at the failure, it's due to that "vect_no_align" is
evaluated as true unexpectedly.

  "selector_expression: ` vect_no_align || {! vector_alignment_reachable} ' 1"

Currently powerpc* checks check_p8vector_hw_available, ppc64le-linux-gnu
has at least Power8 support (that is testing machine supports p8vector run),
so it concludes vect_no_align is true.

proc check_effective_target_vect_no_align { } {
    return [check_cached_effective_target_indexed vect_no_align {
      expr { [istarget mipsisa64*-*-*]
	     || [istarget mips-sde-elf]
	     || [istarget sparc*-*-*]
	     || [istarget ia64-*-*]
	     || [check_effective_target_arm_vect_no_misalign]
	     || ([istarget powerpc*-*-*] && [check_p8vector_hw_available])

I'll fix this in PR113535 which was filed previously for visiting powerpc
specific check in these vect* effective targets.  If the testing just goes
with native cpu type, this issue will become invisible.  I think you can
still push the patch as the testing just exposes another issue.

BR,
Kewen