re PR tree-optimization/71631 (Wrong constant folding)

	PR tree-optimization/71631
	* tree-ssa-reassoc.c (reassociate_bb): Pass true as last argument
	to rewrite_expr_tree even if negate_result, move new_lhs var
	declaration and initialization earlier, for powi_result set afterwards
	new_lhs to lhs.  For negate_result, use new_lhs instead of tmp
	if new_lhs != lhs, and don't shadow gsi var.

	* gcc.c-torture/execute/pr71631.c: New test.

From-SVN: r237782

4 files changed, 55 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 48a2291..b4d4b0b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2016-06-25  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/71631
+	* tree-ssa-reassoc.c (reassociate_bb): Pass true as last argument
+	to rewrite_expr_tree even if negate_result, move new_lhs var
+	declaration and initialization earlier, for powi_result set afterwards
+	new_lhs to lhs.  For negate_result, use new_lhs instead of tmp
+	if new_lhs != lhs, and don't shadow gsi var.
+
 2016-06-24  Jan Hubicka  <hubicka@ucw.cz>
 
 	* predict.c (predict_paths_leading_to, predict_paths_leading_to_edge):
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4a10bf4..105f81f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-06-25  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/71631
+	* gcc.c-torture/execute/pr71631.c: New test.
+
 2016-06-24  Jan Hubicka  <hubicka@ucw.cz>
 
 	* gcc.dg/predict-11.c: New testcase.
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr71631.c b/gcc/testsuite/gcc.c-torture/execute/pr71631.c
new file mode 100644
index 0000000..f27c03e
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr71631.c
@@ -0,0 +1,32 @@
+/* PR tree-optimization/71631 */
+
+volatile char v;
+int a = 1, b = 1, c = 1;
+
+void
+foo (const char *s)
+{
+  while (*s++)
+    v = *s;
+}
+
+int
+main ()
+{
+  volatile int d = 1;
+  volatile int e = 1;
+  int f = 1 / a;
+  int g = 1U < f;
+  int h = 2 + g;
+  int i = 3 % h;
+  int j = e && b;
+  int k = 1 == c;
+  int l = d != 0;
+  short m = (short) (-1 * i * l);
+  short x = j * (k * m);
+  if (i == 1)
+    foo ("AB");
+  if (x != -1)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c
index cdfe06f..9264e0b 100644
--- a/gcc/tree-ssa-reassoc.c
+++ b/gcc/tree-ssa-reassoc.c
@@ -5314,6 +5314,7 @@ reassociate_bb (basic_block bb)
 		    }
 		}
 
+	      tree new_lhs = lhs;
 	      /* If the operand vector is now empty, all operands were 
 		 consumed by the __builtin_powi optimization.  */
 	      if (ops.length () == 0)
@@ -5337,7 +5338,6 @@ reassociate_bb (basic_block bb)
 		  machine_mode mode = TYPE_MODE (TREE_TYPE (lhs));
 		  int ops_num = ops.length ();
 		  int width = get_reassociation_width (ops_num, rhs_code, mode);
-		  tree new_lhs = lhs;
 
 		  if (dump_file && (dump_flags & TDF_DETAILS))
 		    fprintf (dump_file,
@@ -5357,7 +5357,8 @@ reassociate_bb (basic_block bb)
                         swap_ops_for_binary_stmt (ops, len - 3, stmt);
 
 		      new_lhs = rewrite_expr_tree (stmt, 0, ops,
-						   powi_result != NULL);
+						   powi_result != NULL
+						   || negate_result);
                     }
 
 		  /* If we combined some repeated factors into a 
@@ -5372,7 +5373,10 @@ reassociate_bb (basic_block bb)
 		      gimple_set_lhs (lhs_stmt, target_ssa);
 		      update_stmt (lhs_stmt);
 		      if (lhs != new_lhs)
-			target_ssa = new_lhs;
+			{
+			  target_ssa = new_lhs;
+			  new_lhs = lhs;
+			}
 		      mul_stmt = gimple_build_assign (lhs, MULT_EXPR,
 						      powi_result, target_ssa);
 		      gimple_set_location (mul_stmt, gimple_location (stmt));
@@ -5386,10 +5390,11 @@ reassociate_bb (basic_block bb)
 		  stmt = SSA_NAME_DEF_STMT (lhs);
 		  tree tmp = make_ssa_name (TREE_TYPE (lhs));
 		  gimple_set_lhs (stmt, tmp);
+		  if (lhs != new_lhs)
+		    tmp = new_lhs;
 		  gassign *neg_stmt = gimple_build_assign (lhs, NEGATE_EXPR,
 							   tmp);
 		  gimple_set_uid (neg_stmt, gimple_uid (stmt));
-		  gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
 		  gsi_insert_after (&gsi, neg_stmt, GSI_NEW_STMT);
 		  update_stmt (stmt);
 		}