From: Richard Biener <rguenther@suse.de>
Date: Tue, 16 Apr 2024 09:33:48 +0000 (+0200)
Subject: tree-optimization/114736 - SLP DFS walk issue
X-Git-Tag: basepoints/gcc-15~146
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f949481a1f7ab973608a4ffcc0e342ab5a74e8e4;p=thirdparty%2Fgcc.git

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.
---

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;