New POINTER_DIFF_EXPR

New POINTER_DIFF_EXPR

2017-11-21  Marc Glisse  <marc.glisse@inria.fr>

gcc/c/
	* c-fold.c (c_fully_fold_internal): Handle POINTER_DIFF_EXPR.
	* c-typeck.c (pointer_diff): Use POINTER_DIFF_EXPR.

gcc/c-family/
	* c-pretty-print.c (pp_c_additive_expression,
	c_pretty_printer::expression): Handle POINTER_DIFF_EXPR.

gcc/cp/
	* constexpr.c (cxx_eval_constant_expression,
	potential_constant_expression_1): Handle POINTER_DIFF_EXPR.
	* cp-gimplify.c (cp_fold): Likewise.
	* error.c (dump_expr): Likewise.
	* typeck.c (pointer_diff): Use POINTER_DIFF_EXPR.

gcc/
	* doc/generic.texi: Document POINTER_DIFF_EXPR, update
	POINTER_PLUS_EXPR.
	* cfgexpand.c (expand_debug_expr): Handle POINTER_DIFF_EXPR.
	* expr.c (expand_expr_real_2): Likewise.
	* fold-const.c (const_binop, fold_addr_of_array_ref_difference,
	fold_binary_loc): Likewise.
	* match.pd (X-X, P+(Q-P), &D-P, (P+N)-P, P-(P+N), (P+M)-(P+N),
	P-Q==0, -(A-B), X-Z<Y-Z, (X-Z)-(Y-Z), Z-X<Z-Y, (Z-X)-(Z-Y),
	(A-B)+(C-A)): New transformations for POINTER_DIFF_EXPR, based on
	MINUS_EXPR transformations.
	* optabs-tree.c (optab_for_tree_code): Handle POINTER_DIFF_EXPR.
	* tree-cfg.c (verify_expr, verify_gimple_assign_binary): Likewise.
	* tree-inline.c (estimate_operator_cost): Likewise.
	* tree-pretty-print.c (dump_generic_node, op_code_prio,
	op_symbol_code): Likewise.
	* tree-vect-stmts.c (vectorizable_operation): Likewise.
	* vr-values.c (extract_range_from_binary_expr): Likewise.
	* varasm.c (initializer_constant_valid_p_1): Likewise.
	* tree.def: New tree code POINTER_DIFF_EXPR.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@255021 138bc75d-0d04-0410-961f-82ee72b054a4