[PATCH] Fix PR64091

[Richard Biener]

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2014-11-27  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/64088
        * tree-ssa-tail-merge.c (update_debug_stmt): After resetting
        the stmt break from the loop over use operands.

        * gcc.dg/torture/pr64091.c: New testcase.

Index: gcc/tree-ssa-tail-merge.c
===================================================================
--- gcc/tree-ssa-tail-merge.c   (revision 218117)
+++ gcc/tree-ssa-tail-merge.c   (working copy)
@@ -1606,9 +1613,7 @@ update_debug_stmt (gimple stmt)
 {
   use_operand_p use_p;
   ssa_op_iter oi;
-  basic_block bbdef, bbuse;
-  gimple def_stmt;
-  tree name;
+  basic_block bbuse;
 
   if (!gimple_debug_bind_p (stmt))
     return;
@@ -1616,19 +1621,16 @@ update_debug_stmt (gimple stmt)
   bbuse = gimple_bb (stmt);
   FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, oi, SSA_OP_USE)
     {
-      name = USE_FROM_PTR (use_p);
-      gcc_assert (TREE_CODE (name) == SSA_NAME);
-
-      def_stmt = SSA_NAME_DEF_STMT (name);
-      gcc_assert (def_stmt != NULL);
-
-      bbdef = gimple_bb (def_stmt);
+      tree name = USE_FROM_PTR (use_p);
+      gimple def_stmt = SSA_NAME_DEF_STMT (name);
+      basic_block bbdef = gimple_bb (def_stmt);
       if (bbdef == NULL || bbuse == bbdef
          || dominated_by_p (CDI_DOMINATORS, bbuse, bbdef))
        continue;
 
       gimple_debug_bind_reset_value (stmt);
       update_stmt (stmt);
+      break;
     }
 }
 
Index: gcc/testsuite/gcc.dg/torture/pr64091.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr64091.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr64091.c      (working copy)
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-g" } */
+
+extern int foo(void);
+
+int main(void)
+{
+  int i, a, b;
+
+  if (foo())
+    return 0;
+
+  for (i = 0, a = 0, b = 0; i < 3; i++, a++)
+  {
+    if (foo())
+      break;
+
+    if (b += a)
+      a = 0;
+  }
+
+  if (!a)
+    return 2;
+
+  b += a;
+
+  return 0;
+}