From: Richard Biener <rguenther@suse.de>
Date: Fri, 1 Aug 2014 07:40:01 +0000 (+0000)
Subject: re PR tree-optimization/61964 (krb5 database propagation enters infinite loop; reduce... 
X-Git-Tag: releases/gcc-4.8.4~322
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf66b54c94589c13a340a72413a5530adf23dd43;p=thirdparty%2Fgcc.git

re PR tree-optimization/61964 (krb5 database propagation enters infinite loop; reduced test case)

2014-08-01  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/61964
	* tree-ssa-tail-merge.c (gimple_operand_equal_value_p): New
	function merged from trunk.
	(gimple_equal_p): Handle non-SSA LHS solely by structural
	equality.

	* gcc.dg/torture/pr61964.c: New testcase.
	* gcc.dg/pr51879-18.c: XFAIL.

From-SVN: r213405
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fb1ebec5f80f..7813061ec446 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2014-08-01  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/61964
+	* tree-ssa-tail-merge.c (gimple_operand_equal_value_p): New
+	function merged from trunk.
+	(gimple_equal_p): Handle non-SSA LHS solely by structural
+	equality.
+
 2014-07-25  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/alpha/elf.h: Define TARGET_UNWIND_TABLES_DEFAULT.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index da156a60226e..675ec254df30 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2014-08-01  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/61964
+	* gcc.dg/torture/pr61964.c: New testcase.
+	* gcc.dg/pr51879-18.c: XFAIL.
+
 2014-07-28  Richard Biener  <rguenther@suse.de>
 
 	PR rtl-optimization/61801
diff --git a/gcc/testsuite/gcc.dg/pr51879-18.c b/gcc/testsuite/gcc.dg/pr51879-18.c
index 95629f12261d..9b3cb80a4e6f 100644
--- a/gcc/testsuite/gcc.dg/pr51879-18.c
+++ b/gcc/testsuite/gcc.dg/pr51879-18.c
@@ -13,5 +13,5 @@ void bar (int c, int *p)
     *q = foo ();
 }
 
-/* { dg-final { scan-tree-dump-times "foo \\(" 1 "pre"} } */
+/* { dg-final { scan-tree-dump-times "foo \\(" 1 "pre" { xfail *-*-* } } } */
 /* { dg-final { cleanup-tree-dump "pre" } } */
diff --git a/gcc/testsuite/gcc.dg/torture/pr61964.c b/gcc/testsuite/gcc.dg/torture/pr61964.c
new file mode 100644
index 000000000000..a03cfdc37bd3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr61964.c
@@ -0,0 +1,33 @@
+/* { dg-do run } */
+
+extern void abort (void);
+
+struct node { struct node *next, *prev; } node;
+struct head { struct node *first; } heads[5];
+int k = 2;
+struct head *head = &heads[2];
+
+static int __attribute__((noinline))
+foo()
+{
+  node.prev = (void *)head;
+  head->first = &node;
+
+  struct node *n = head->first;
+  struct head *h = &heads[k];
+
+  if (n->prev == (void *)h)
+    h->first = n->next;
+  else
+    n->prev->next = n->next;
+
+  n->next = h->first;
+  return n->next == &node;
+}
+
+int main()
+{
+  if (foo ())
+    abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c
index 419b4ec024e9..61add6e04459 100644
--- a/gcc/tree-ssa-tail-merge.c
+++ b/gcc/tree-ssa-tail-merge.c
@@ -1060,6 +1060,24 @@ set_cluster (basic_block bb1, basic_block bb2)
     gcc_unreachable ();
 }
 
+/* Return true if gimple operands T1 and T2 have the same value.  */
+
+static bool
+gimple_operand_equal_value_p (tree t1, tree t2)
+{
+  if (t1 == t2)
+    return true;
+
+  if (t1 == NULL_TREE
+      || t2 == NULL_TREE)
+    return false;
+
+  if (operand_equal_p (t1, t2, 0))
+    return true;
+
+  return gvn_uses_equal (t1, t2);
+}
+
 /* Return true if gimple statements S1 and S2 are equal.  Gimple_bb (s1) and
    gimple_bb (s2) are members of SAME_SUCC.  */
 
@@ -1122,8 +1140,9 @@ gimple_equal_p (same_succ same_succ, gimple s1, gimple s2)
       lhs2 = gimple_get_lhs (s2);
       if (TREE_CODE (lhs1) != SSA_NAME
 	  && TREE_CODE (lhs2) != SSA_NAME)
-	return (vn_valueize (gimple_vdef (s1))
-		== vn_valueize (gimple_vdef (s2)));
+	return (operand_equal_p (lhs1, lhs2, 0)
+		&& gimple_operand_equal_value_p (gimple_assign_rhs1 (s1),
+						 gimple_assign_rhs1 (s2)));
       else if (TREE_CODE (lhs1) == SSA_NAME
 	       && TREE_CODE (lhs2) == SSA_NAME)
 	return vn_valueize (lhs1) == vn_valueize (lhs2);