re PR tree-optimization/49087 (crash in vect_is_slp_reduction)

        PR tree-optimization/49087
        * tree-vect-loop.c (vect_is_slp_reduction): Fail if
        LHS has no uses.

From-SVN: r174026

gcc/ChangeLog

+2011-05-22  Ira Rosen  <ira.rosen@linaro.org>
+
+	PR tree-optimization/49087
+	* tree-vect-loop.c (vect_is_slp_reduction): Fail if
+	LHS has no uses.
+
 2011-05-21  Jason Merrill  <jason@redhat.com>
 
 	PR c++/49092

gcc/testsuite/ChangeLog

+2011-05-22  Ira Rosen  <ira.rosen@linaro.org>
+
+	PR tree-optimization/49087
+	* gcc.dg/vect/O3-pr49087.c: New test.
+
 2011-05-21  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/debug/const5.C: New.

gcc/testsuite/gcc.dg/vect/O3-pr49087.c

+/* { dg-do compile } */
+
+static char func2() { }
+
+struct S0
+{
+ int t;
+};
+
+int g;
+
+struct S0 s0;
+
+int 
+foo (int arg)
+{
+  int *ptr = &g;
+  int i, j;
+  for (i = 0; i < 10; i += 1)
+    {
+      for (j = 0; j < 1; j += 1)
+	{
+	  int k;
+	  if (arg)
+	    {
+	      int l;
+	      for (k = 1; arg < 10; arg = func2 ())
+		{
+		  return l;
+		}
+	    }
+	  *ptr = func2 () ^ s0.t;
+	}
+    }
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */

gcc/tree-vect-loop.c

@@ -1704,7 +1704,7 @@ vect_is_slp_reduction (loop_vec_info loop_info, gimple phi, gimple first_stmt)
   tree lhs;
   imm_use_iterator imm_iter;
   use_operand_p use_p;
-  int nloop_uses, size = 0;
+  int nloop_uses, size = 0, nuses;
   bool found = false;
 
   if (loop != vect_loop)
@@ -1715,9 +1715,11 @@ vect_is_slp_reduction (loop_vec_info loop_info, gimple phi, gimple first_stmt)
   while (1)
     {
       nloop_uses = 0;
+      nuses = 0;
       FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs)
         {
           use_stmt = USE_STMT (use_p);
+          nuses++;
           if (is_gimple_debug (use_stmt))
             continue;
 
@@ -1739,6 +1741,10 @@ vect_is_slp_reduction (loop_vec_info loop_info, gimple phi, gimple first_stmt)
             return false;
         }
 
+      /* We reached a statement with no uses.  */
+      if (nuses == 0)
+	return false;
+
       if (found)
         break;