re PR middle-end/39976 (Big sixtrack degradation on powerpc 32/64 after revision...

re PR middle-end/39976 (Big sixtrack degradation on powerpc 32/64 after revision r146817)

2011-12-08  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR middle-end/39976
	* tree-ssa-dom.c (enum expr_kind): Add EXPR_PHI.
	(struct hashable_expr): Add struct phi field.
	(initialize_hash_element): Handle phis; change to use XCNEWVEC.
	(hashable_expr_equal_p): Handle phis.
	(iterative_hash_hashable_expr): Likewise.
	(print_expr_hash_elt): Likewise.
	(free_expr_hash_elt): Likewise.
	(dom_opt_enter_block): Create equivalences from redundant phis.
	(eliminate_redundant_computations): Handle redundant phis.
	(lookup_avail_expr): Handle phis.

From-SVN: r182140