From f949481a1f7ab973608a4ffcc0e342ab5a74e8e4 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Tue, 16 Apr 2024 11:33:48 +0200
Subject: [PATCH] tree-optimization/114736 - SLP DFS walk issue
The following fixes a DFS walk issue when identifying to be ignored
latch edges. We have (bogus) SLP_TREE_REPRESENTATIVEs for VEC_PERM
nodes so those have to be explicitly ignored as possibly being PHIs.
PR tree-optimization/114736
* tree-vect-slp.cc (vect_optimize_slp_pass::is_cfg_latch_edge):
Do not consider VEC_PERM_EXPRs as PHI use.
* gfortran.dg/vect/pr114736.f90: New testcase.
---
gcc/testsuite/gfortran.dg/vect/pr114736.f90 | 14 ++++++++++++++
gcc/tree-vect-slp.cc | 3 ++-
2 files changed, 16 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gfortran.dg/vect/pr114736.f90
diff --git a/gcc/testsuite/gfortran.dg/vect/pr114736.f90 b/gcc/testsuite/gfortran.dg/vect/pr114736.f90
new file mode 100644
index 000000000000..cdbfb6f415a9
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/vect/pr114736.f90
@@ -0,0 +1,14 @@
+! { dg-do compile }
+! { dg-additional-options "-O3" }
+
+SUBROUTINE MY_ROUTINE (N, A, B )
+IMPLICIT NONE
+INTEGER, INTENT(IN) :: N
+COMPLEX, INTENT(IN) :: A(N)
+COMPLEX, INTENT(OUT) :: B(N)
+INTEGER :: II
+B(:) = (1.,0.)
+DO II = 1, N-1
+ B(II) = A(N-II+1) / A(N-II)
+ENDDO
+END SUBROUTINE MY_ROUTINE
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index f57684ca6856..30589e19a175 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -4309,7 +4309,8 @@ vect_optimize_slp_pass::is_cfg_latch_edge (graph_edge *ud)
{
slp_tree use = m_vertices[ud->src].node;
slp_tree def = m_vertices[ud->dest].node;
- if (SLP_TREE_DEF_TYPE (use) != vect_internal_def
+ if ((SLP_TREE_DEF_TYPE (use) != vect_internal_def
+ || SLP_TREE_CODE (use) == VEC_PERM_EXPR)
|| SLP_TREE_DEF_TYPE (def) != vect_internal_def)
return false;
--
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