[Tuples][Patch] Convert pass_remove_useless_stmts and related constant folding infrastructure

["Bill Maddox" <maddox at google dot com>]

This patch converts pass_remove_useless_stmts and ports some of the
constant folding infrastructure used in ccp.

--Bill

	* tree-ssa-ccp.c (maybe_fold_stmt_addition):
	Reinstated this function for tuples as-is.
	(valid_gimple_rhs_p): New function.  Mostly lifted from
	valid_gimple_epxression_p, which is likely obsolete.
	(fold_stmt_r): Reinstated commented-out cases for
	tuples. Replaced call to obsolete function set_rhs.
	(get_maxval_strlen): Convert to tuples.
	(ccp_fold_builtin): Partial conversion to tuples.
	(fold_gimple_assign): New function.
	(fold_gimple_cond): New function.
	(fold_gimple_call): New function.
	(fold_stmt): Convert to tuples.
	(fold_stmt_inplace): Convert to tuples.
	* tree-ssa-propagate.c (substitute_and_fold):
	Update call to fold_stmt for revised argument signature.
	* gimple-dummy.c (fold_stmt): Removed dummy definition.
	* gimplify.c (gimplify_call_expr): Removed obsolete
	manipulation of TREE_NOTHROW flag.
	* cfgexpand.c (gimple_to_tree): Set nothrow flag
	of call expression based on call statement flags.
	Handle GIMPLE_NOP statement.
	* tree-flow.h (notice_special_calls, fold_stmt):
	Update prototypes for tuples.
	* gimple.c (gimple_cond_set_condition_from_tree):
	New function.
	(gimple_seq_has_side_effects): New function.
	* gimple.h (gimple_cond_set_condition_from_tree,
	gimple_seq_has_side_effects): New prototypes.
	(gimple_call_nothrow_p): New function.
	(gsi_stmt_ptr): Add comment regarding usage of this
	function vs. gsi_replace.
	* tree-cfg.c (struct rus_data): Convert to tuples.
	(remove_useless_stmts_1, remove_useless_stmts_warn_notreached,
	remove_useless_stmts_cond, remove_useless_stmts_tf,
	remove_useless_stmts_tc, remove_useless_stmts_goto,
	remove_useless_stmts_label, notice_special_calls,
	remove_useless_stmts): Convert to tuples.
	(update_call_expr_flags): Removed.

Attachment: tuples-rus-patch-02-20.txt
Description: Text document