re PR tree-optimization/51491 (ccp when converting from alloca should add a CLOBBER to right before __builtin_stack_restore)

2011-12-17  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/51491
	* tree-ssa-ccp.c (insert_clobber_before_stack_restore)
	(gsi_prev_dom_bb_nondebug, insert_clobbers_for_var): New function.
	(ccp_fold_stmt): Use insert_clobbers_for_var after a successful
	fold_builtin_alloca_with_align.
	(ccp_visit_stmt): Calculate and free dominator info.

From-SVN: r182432