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.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@221034 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1bbd014..9743435 100644 (file)
--- 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 1852d25..93fc50f 100644 (file)
--- 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 (file)
index 0000000..0714d8c
--- /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 ce37053..2e933e7 100644 (file)
--- 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));