From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 26 Feb 2015 21:03:14 +0000 (+0100)
Subject: re PR tree-optimization/65216 (wrong code at -O3 on x86_64-linux-gnu)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d288c0abe62b0ea097852174651c5b87c2ac7800;p=gcc.git

re PR tree-optimization/65216 (wrong code at -O3 on x86_64-linux-gnu)

	PR tree-optimization/65216
	* tree-ssa-reassoc.c (rewrite_expr_tree): Force creation of
	new stmt and new SSA_NAME for lhs whenever the arguments have
	changed and weren't just swapped.  Fix comment typo.

	* gcc.c-torture/execute/pr65216.c: New test.

From-SVN: r221034
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1bbd014bd16..97434356dac 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 2015-02-26  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/65216
+	* tree-ssa-reassoc.c (rewrite_expr_tree): Force creation of
+	new stmt and new SSA_NAME for lhs whenever the arguments have
+	changed and weren't just swapped.  Fix comment typo.
+
 	PR tree-optimization/65215
 	* tree-ssa-math-opts.c (find_bswap_or_nop_load): Return false
 	for PDP endian targets.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1852d25fce9..93fc50f2a91 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2015-02-26  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/65216
+	* gcc.c-torture/execute/pr65216.c: New test.
+
 	PR tree-optimization/65215
 	* gcc.c-torture/execute/pr65215-1.c: New test.
 	* gcc.c-torture/execute/pr65215-2.c: New test.
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr65216.c b/gcc/testsuite/gcc.c-torture/execute/pr65216.c
new file mode 100644
index 00000000000..0714d8ceebb
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr65216.c
@@ -0,0 +1,20 @@
+/* PR tree-optimization/65216 */
+
+int a, b = 62, e;
+volatile int c, d;
+
+int
+main ()
+{
+  int f = 0;
+  for (a = 0; a < 2; a++)
+    {
+      b &= (8 ^ f) & 1;
+      for (e = 0; e < 6; e++)
+	if (c)
+	  f = d;
+    }
+  if (b != 0)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c
index ce37053bdb3..2e933e769fc 100644
--- a/gcc/tree-ssa-reassoc.c
+++ b/gcc/tree-ssa-reassoc.c
@@ -3532,7 +3532,7 @@ rewrite_expr_tree (gimple stmt, unsigned int opindex,
 
   /* The final recursion case for this function is that you have
      exactly two operations left.
-     If we had one exactly one op in the entire list to start with, we
+     If we had exactly one op in the entire list to start with, we
      would have never called this function, and the tail recursion
      rewrites them one at a time.  */
   if (opindex + 2 == ops.length ())
@@ -3553,7 +3553,11 @@ rewrite_expr_tree (gimple stmt, unsigned int opindex,
 	      print_gimple_stmt (dump_file, stmt, 0, 0);
 	    }
 
-	  if (changed)
+	  /* Even when changed is false, reassociation could have e.g. removed
+	     some redundant operations, so unless we are just swapping the
+	     arguments or unless there is no change at all (then we just
+	     return lhs), force creation of a new SSA_NAME.  */
+	  if (changed || ((rhs1 != oe2->op || rhs2 != oe1->op) && opindex))
 	    {
 	      gimple insert_point = find_insert_point (stmt, oe1->op, oe2->op);
 	      lhs = make_ssa_name (TREE_TYPE (lhs));