diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d20066c4cbb4..d053f30da87a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2008-10-01  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/37617
+	* tree-ssa-pre.c (create_expression_by_pieces): During FRE
+	do not add to the NEW_SETS.
+
 2008-10-01  Richard Guenther  <rguenther@suse.de>
 
         PR middle-end/37285
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 16a233a5c7f6..d2f70a06b657 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2008-10-01  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/37617
+	* gcc.c-torture/compile/pr37617.c: New testcase.
+
 2008-10-01  Richard Guenther  <rguenther@suse.de>
 
         PR middle-end/37285
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr37617.c b/gcc/testsuite/gcc.c-torture/compile/pr37617.c
new file mode 100644
index 000000000000..901b8cabf225
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr37617.c
@@ -0,0 +1,19 @@
+typedef union
+{
+  char *string;
+  double dval;
+  float fval;
+} yystype;
+char *f(void)
+{
+  yystype tok;
+  tok.dval = 0;
+  return (tok.string);
+}
+char *f1(void)
+{
+  yystype tok;
+  tok.fval = 0;
+  return (tok.string);
+}
+
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index cd344af2d101..84c884b060cf 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -2885,7 +2885,8 @@ create_expression_by_pieces (basic_block block, pre_expr expr,
 	      VN_INFO (forcedname)->value_id = get_next_value_id ();
 	      nameexpr = get_or_alloc_expr_for_name (forcedname);
 	      add_to_value (VN_INFO (forcedname)->value_id, nameexpr);
-	      bitmap_value_replace_in_set (NEW_SETS (block), nameexpr);
+	      if (!in_fre)
+		bitmap_value_replace_in_set (NEW_SETS (block), nameexpr);
 	      bitmap_value_replace_in_set (AVAIL_OUT (block), nameexpr);
 	    }
 	  mark_symbols_for_renaming (stmt);