2005-01-30  Daniel Berlin  <dberlin@dberlin.org>

	Fix PR tree-optimization/19624

	* Makefile.in (tree-ssa-pre.o): Add CFGLOOP_H.
	* tree-ssa-pre.c: Add cfgloop.h.
	Update comment.
	(pre_stats): New member, constified.
	(inserted_exprs): New static variable.
	(NECESSARY): New macro.
	(create_expression_by_pieces): Fold the expression, and
	mark it as defaulting to not necessary. Also put in
	inserted_exprs.
	(fully_constant_expression): New function.
	(insert_into_preds_of_block): Modify to not insert phis when we
	are playing with induction variables.
	Push phis onto the inserted_exprs vector, and mark them as not
	necessary by default.
	(insert_aux): Call fully_constant_expression on eprime.
	If all edges produce the same value, mark it constant.
	(mark_operand_necessary): New function.
	(remove_dead_inserted_code): New function.
	(init_pre): Init loop optimizer to get loop info.
	(fini_pre): Free loop_optimizer, and inserted_exprs vec.
	(execute_pre): Commit edge inserts, then remove dead code.

From-SVN: r94448