Re: [PATCH] tree-optimization/110221 - SLP and loop mask/len

["Andre Vieira (lists)" <andre.simoesdiasvieira@arm.com>]

Hi,

Bootstrapped and tested the gcc-13 backport of this on gcc-12 for 
aarch64-unknown-linux-gnu and x86_64-pc-linux-gnu and no regressions.

OK to push to gcc-12 branch?

Kind regards,
Andre Vieira

On 10/11/2023 13:16, Richard Biener wrote:
> The following fixes the issue that when SLP stmts are internal defs
> but appear invariant because they end up only using invariant defs
> then they get scheduled outside of the loop.  This nice optimization
> breaks down when loop masks or lens are applied since those are not
> explicitly tracked as dependences.  The following makes sure to never
> schedule internal defs outside of the vectorized loop when the
> loop uses masks/lens.
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
> 
> 	PR tree-optimization/110221
> 	* tree-vect-slp.cc (vect_schedule_slp_node): When loop
> 	masking / len is applied make sure to not schedule
> 	intenal defs outside of the loop.
> 
> 	* gfortran.dg/pr110221.f: New testcase.
> ---
>   gcc/testsuite/gfortran.dg/pr110221.f | 17 +++++++++++++++++
>   gcc/tree-vect-slp.cc                 | 10 ++++++++++
>   2 files changed, 27 insertions(+)
>   create mode 100644 gcc/testsuite/gfortran.dg/pr110221.f
> 
> diff --git a/gcc/testsuite/gfortran.dg/pr110221.f b/gcc/testsuite/gfortran.dg/pr110221.f
> new file mode 100644
> index 00000000000..8b57384313a
> --- /dev/null
> +++ b/gcc/testsuite/gfortran.dg/pr110221.f
> @@ -0,0 +1,17 @@
> +C PR middle-end/68146
> +C { dg-do compile }
> +C { dg-options "-O2 -w" }
> +C { dg-additional-options "-mavx512f --param vect-partial-vector-usage=2" { target avx512f } }
> +      SUBROUTINE CJYVB(V,Z,V0,CBJ,CDJ,CBY,CYY)
> +      IMPLICIT DOUBLE PRECISION (A,B,G,O-Y)
> +      IMPLICIT COMPLEX*16 (C,Z)
> +      DIMENSION CBJ(0:*),CDJ(0:*),CBY(0:*)
> +      N=INT(V)
> +      CALL GAMMA2(VG,GA)
> +      DO 65 K=1,N
> +        CBY(K)=CYY
> +65    CONTINUE
> +      CDJ(0)=V0/Z*CBJ(0)-CBJ(1)
> +      DO 70 K=1,N
> +70      CDJ(K)=-(K+V0)/Z*CBJ(K)+CBJ(K-1)
> +      END
> diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
> index 3e5814c3a31..80e279d8f50 100644
> --- a/gcc/tree-vect-slp.cc
> +++ b/gcc/tree-vect-slp.cc
> @@ -9081,6 +9081,16 @@ vect_schedule_slp_node (vec_info *vinfo,
>         /* Emit other stmts after the children vectorized defs which is
>   	 earliest possible.  */
>         gimple *last_stmt = NULL;
> +      if (auto loop_vinfo = dyn_cast <loop_vec_info> (vinfo))
> +	if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)
> +	    || LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
> +	  {
> +	    /* But avoid scheduling internal defs outside of the loop when
> +	       we might have only implicitly tracked loop mask/len defs.  */
> +	    gimple_stmt_iterator si
> +	      = gsi_after_labels (LOOP_VINFO_LOOP (loop_vinfo)->header);
> +	    last_stmt = *si;
> +	  }
>         bool seen_vector_def = false;
>         FOR_EACH_VEC_ELT (SLP_TREE_CHILDREN (node), i, child)
>   	if (SLP_TREE_DEF_TYPE (child) == vect_internal_def)