[PATCH] fix -Werror=maybe-uninitialized in tree-ssa-loop-ivopts.c (PR bootstrap/50218)

[Mikael Pettersson]

The recent r178104 change to tree-ssa-loop-ivopts.c broke bootstrap on i686-linux
because stage2 gcc considers the variable 'comp' used but possibly uninitialized,
see PR50218.  Initializing it to ERROR_MARK solves the problem, and is consistent
with how other parts of r178104 represent absent/impossible 'comp' values.

Ok for trunk?  (I don't have svn write access.)

/Mikael

gcc/

2011-08-20  Mikael Pettersson  <mikpe@it.uu.se>

	PR bootstrap/50218
	* tree-ssa-loop-ivopts.c (determine_use_iv_cost_condition): Initialize comp.

--- gcc-4.7-20110827/gcc/tree-ssa-loop-ivopts.c.~1~	2011-08-26 15:36:28.000000000 +0200
+++ gcc-4.7-20110827/gcc/tree-ssa-loop-ivopts.c	2011-08-28 10:13:34.000000000 +0200
@@ -4757,7 +4757,7 @@ determine_use_iv_cost_condition (struct 
   bool ok;
   int elim_inv_expr_id = -1, express_inv_expr_id = -1, inv_expr_id;
   tree *control_var, *bound_cst;
-  enum tree_code comp;
+  enum tree_code comp = ERROR_MARK;
 
   /* Only consider real candidates.  */
   if (!cand->iv)