re PR middle-end/66375 (wrong code at -O2 and -O3 on x86_64-linux-gnu)

2015-06-03  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/66375
	* tree-scalar-evolution.c (follow_ssa_edge_binary): First
	add to the evolution before following SSA edges.

	* gcc.dg/torture/pr66375.c: New testcase.

From-SVN: r224060

4 files changed, 48 insertions, 26 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 07743bb..06dda14 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2015-06-03  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/66375
+	* tree-scalar-evolution.c (follow_ssa_edge_binary): First
+	add to the evolution before following SSA edges.
+
 2015-06-03  Bin Cheng  <bin.cheng@arm.com>
 
 	* tree-ssa-loop-ivopts.c (dump_iv): New parameter.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3abe065..9fd5941 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-06-03  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/66375
+	* gcc.dg/torture/pr66375.c: New testcase.
+
 2015-06-03  Bin Cheng  <bin.cheng@arm.com>
 
 	* gcc.dg/tree-ssa/pr65447.c: Increase searching number.
diff --git a/gcc/testsuite/gcc.dg/torture/pr66375.c b/gcc/testsuite/gcc.dg/torture/pr66375.c
new file mode 100644
index 0000000..2447b43
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr66375.c
@@ -0,0 +1,13 @@
+/* { dg-do run } */
+
+int a;
+extern void abort (void);
+int main ()
+{
+  int c = 0;
+  for (; a < 13; ++a)
+    c = (signed char)c - 11;
+  if (c != 113)
+    abort ();
+  return 0;
+}
diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c
index 013fc50..3a2c284 100644
--- a/gcc/tree-scalar-evolution.c
+++ b/gcc/tree-scalar-evolution.c
@@ -958,27 +958,25 @@ follow_ssa_edge_binary (struct loop *loop, gimple at_stmt,
 	      limit++;
 
 	      evol = *evolution_of_loop;
-	      res = follow_ssa_edge
-		(loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, &evol, limit);
-
-	      if (res == t_true)
-		*evolution_of_loop = add_to_evolution
+	      evol = add_to_evolution
 		  (loop->num,
 		   chrec_convert (type, evol, at_stmt),
 		   code, rhs1, at_stmt);
-
+	      res = follow_ssa_edge
+		(loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, &evol, limit);
+	      if (res == t_true)
+		*evolution_of_loop = evol;
 	      else if (res == t_false)
 		{
+		  *evolution_of_loop = add_to_evolution
+		      (loop->num,
+		       chrec_convert (type, *evolution_of_loop, at_stmt),
+		       code, rhs0, at_stmt);
 		  res = follow_ssa_edge
 		    (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi,
 		     evolution_of_loop, limit);
-
 		  if (res == t_true)
-		    *evolution_of_loop = add_to_evolution
-		      (loop->num,
-		       chrec_convert (type, *evolution_of_loop, at_stmt),
-		       code, rhs0, at_stmt);
-
+		    ;
 		  else if (res == t_dont_know)
 		    *evolution_of_loop = chrec_dont_know;
 		}
@@ -991,15 +989,15 @@ follow_ssa_edge_binary (struct loop *loop, gimple at_stmt,
 	    {
 	      /* Match an assignment under the form:
 		 "a = b + ...".  */
+	      *evolution_of_loop = add_to_evolution
+		  (loop->num, chrec_convert (type, *evolution_of_loop,
+					     at_stmt),
+		   code, rhs1, at_stmt);
 	      res = follow_ssa_edge
 		(loop, SSA_NAME_DEF_STMT (rhs0), halting_phi,
 		 evolution_of_loop, limit);
 	      if (res == t_true)
-		*evolution_of_loop = add_to_evolution
-		  (loop->num, chrec_convert (type, *evolution_of_loop,
-					     at_stmt),
-		   code, rhs1, at_stmt);
-
+		;	
 	      else if (res == t_dont_know)
 		*evolution_of_loop = chrec_dont_know;
 	    }
@@ -1009,15 +1007,15 @@ follow_ssa_edge_binary (struct loop *loop, gimple at_stmt,
 	{
 	  /* Match an assignment under the form:
 	     "a = ... + c".  */
+	  *evolution_of_loop = add_to_evolution
+	      (loop->num, chrec_convert (type, *evolution_of_loop,
+					 at_stmt),
+	       code, rhs0, at_stmt);
 	  res = follow_ssa_edge
 	    (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi,
 	     evolution_of_loop, limit);
 	  if (res == t_true)
-	    *evolution_of_loop = add_to_evolution
-	      (loop->num, chrec_convert (type, *evolution_of_loop,
-					 at_stmt),
-	       code, rhs0, at_stmt);
-
+	    ;
 	  else if (res == t_dont_know)
 	    *evolution_of_loop = chrec_dont_know;
 	}
@@ -1042,13 +1040,13 @@ follow_ssa_edge_binary (struct loop *loop, gimple at_stmt,
 	  if (TREE_CODE (rhs1) == SSA_NAME)
 	    limit++;
 
+	  *evolution_of_loop = add_to_evolution
+	      (loop->num, chrec_convert (type, *evolution_of_loop, at_stmt),
+	       MINUS_EXPR, rhs1, at_stmt);
 	  res = follow_ssa_edge (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi,
 				 evolution_of_loop, limit);
 	  if (res == t_true)
-	    *evolution_of_loop = add_to_evolution
-	      (loop->num, chrec_convert (type, *evolution_of_loop, at_stmt),
-	       MINUS_EXPR, rhs1, at_stmt);
-
+	    ;
 	  else if (res == t_dont_know)
 	    *evolution_of_loop = chrec_dont_know;
 	}