[gcc r15-1706] tree-optimization/115640 - outer loop vect with inner SLP permute

[Richard Biener]

https://gcc.gnu.org/g:0192341a07b8ea30f631cf4afdc6fcf3fa7ce838

commit r15-1706-g0192341a07b8ea30f631cf4afdc6fcf3fa7ce838
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Jun 26 14:07:51 2024 +0200

    tree-optimization/115640 - outer loop vect with inner SLP permute
    
    The following fixes wrong-code when using outer loop vectorization
    and an inner loop SLP access with permutation.  A wrong adjustment
    to the IV increment is then applied on GCN.
    
            PR tree-optimization/115640
            * tree-vect-stmts.cc (vectorizable_load): With an inner
            loop SLP access to not apply a gap adjustment.

Diff:
---
 gcc/tree-vect-stmts.cc | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 0b0761bf799..7b889f31645 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -10512,9 +10512,14 @@ vectorizable_load (vec_info *vinfo,
 	     whole group, not only the number of vector stmts the
 	     permutation result fits in.  */
 	  unsigned scalar_lanes = SLP_TREE_LANES (slp_node);
-	  if (slp_perm
-	      && (group_size != scalar_lanes 
-		  || !multiple_p (nunits, group_size)))
+	  if (nested_in_vect_loop)
+	    /* We do not support grouped accesses in a nested loop,
+	       instead the access is contiguous but it might be
+	       permuted.  No gap adjustment is needed though.  */
+	    vec_num = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
+	  else if (slp_perm
+		   && (group_size != scalar_lanes
+		       || !multiple_p (nunits, group_size)))
 	    {
 	      /* We don't yet generate such SLP_TREE_LOAD_PERMUTATIONs for
 		 variable VF; see vect_transform_slp_perm_load.  */