From e0e3ff695ab4f56d3a69e42303a9af13a23fcc15 Mon Sep 17 00:00:00 2001
From: xiezhiheng <xiezhiheng@huawei.com>
Date: Tue, 5 Dec 2023 14:25:14 +0800
Subject: [PATCH] [Backport] re PR tree-optimization/84552 (Compile time hog w/
 -O2 -floop-nest-optimize -fno-tree-copy-prop -fno-tree-fre
 -fno-tree-loop-ivcanon)

Reference: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=24545562ca5ece2615f8178ad6c6eb0be4fe6b3f
---
 gcc/testsuite/gcc.dg/graphite/pr84552.c | 23 +++++++++++++++++++++++
 gcc/tree-scalar-evolution.c             |  6 +++++-
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/graphite/pr84552.c

diff --git a/gcc/testsuite/gcc.dg/graphite/pr84552.c b/gcc/testsuite/gcc.dg/graphite/pr84552.c
new file mode 100644
index 000000000..15cbb0848
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/graphite/pr84552.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -floop-nest-optimize -fno-tree-copy-prop -fno-tree-fre -fno-tree-loop-ivcanon" } */
+
+int cx;
+
+int
+e6 (int pj, int xe)
+{
+  for (cx = 0; cx < 2; ++cx)
+    while (xe < 1)
+      {
+	for (cx = 0; cx < 2; ++cx)
+	  pj *= 2;
+
+	if (cx != 0)
+	  goto o3;
+
+	++xe;
+      }
+
+o3:
+  return pj;
+}
diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c
index cbd17e864..790050a20 100644
--- a/gcc/tree-scalar-evolution.c
+++ b/gcc/tree-scalar-evolution.c
@@ -280,6 +280,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "params.h"
 #include "tree-ssa-propagate.h"
 #include "gimple-fold.h"
+#include "tree-into-ssa.h"
 
 static tree analyze_scalar_evolution_1 (struct loop *, tree, tree);
 static tree analyze_scalar_evolution_for_address_of (struct loop *loop,
@@ -1532,7 +1533,10 @@ static tree
 follow_copies_to_constant (tree var)
 {
   tree res = var;
-  while (TREE_CODE (res) == SSA_NAME)
+  while (TREE_CODE (res) == SSA_NAME
+	 /* We face not updated SSA form in multiple places and this walk
+	    may end up in sibling loops so we have to guard it.  */
+	 && !name_registered_for_update_p (res))
     {
       gimple *def = SSA_NAME_DEF_STMT (res);
       if (gphi *phi = dyn_cast <gphi *> (def))
-- 
2.19.1