re PR tree-optimization/52548 (missed PRE optimization when function call follows to-be hoisted variable)

2012-03-22  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52548
	* tree-ssa-pre.c (valid_in_sets): Remove handling of invalidation
	because of clobbers.
	(prune_clobbered_mems): New function.
	(compute_antic_aux): Use it to prune ANTIC_OUT.
	(compute_partial_antic_aux): Use it to prune PA_IN.
	(compute_avail): Only insert expressions into EXP_GEN that
	are not invalidated when translated up to the beginning of
	the block.

	* gcc.dg/tree-ssa/ssa-pre-29.c: New testcase.

From-SVN: r185691