tree-ssanames, match.pd: get_nonzero_bits/with_*_nonzero_bits* cleanups and improveme...

tree-ssanames, match.pd: get_nonzero_bits/with_*_nonzero_bits* cleanups and improvements [PR117420]

The following patch implements the with_*_nonzero_bits* cleanups and
improvements I was talking about.

get_nonzero_bits is extended to also handle BIT_AND_EXPR (as a tree or
as SSA_NAME with BIT_AND_EXPR def_stmt), new function is added for the
bits known to be set (get_known_nonzero_bits) and the match.pd predicates
are renamed and adjusted, so that there is no confusion on which one to
use (one is named and documented to be internal), changed so that it can be
used only as a simple predicate, not match some operands, and that it doesn't
try to match twice for the GIMPLE case (where SSA_NAME with integral or pointer
type matches, but SSA_NAME with BIT_AND_EXPR def_stmt matched differently).
Furthermore, get_nonzero_bits just returns the all bits set (or
get_known_nonzero_bits no bits set) fallback if the argument isn't a
SSA_NAME (nor INTEGER_CST or whatever the functions handle explicitly).

2024-12-03  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/117420
	* tree-ssanames.h (get_known_nonzero_bits): Declare.
	* tree-ssanames.cc (get_nonzero_bits): New wrapper function.  Move old
	definition to ...
	(get_nonzero_bits_1): ... here, add static.  Change widest_int in
	function comment to wide_int.
	(get_known_nonzero_bits_1, get_known_nonzero_bits): New functions.
	* match.pd (with_possible_nonzero_bits2): Rename to ...
	(with_possible_nonzero_bits): ... this.  Guard the bit_and case with
	#if GENERIC.  Change to a normal match predicate without parameters.
	Rename the old with_possible_nonzero_bits match to ...
	(with_possible_nonzero_bits_1): ... this.
	(with_certain_nonzero_bits2): Remove.
	(with_known_nonzero_bits_1, with_known_nonzero_bits): New match
	predicates.
	(X == C (or X & Z == Y | C) is impossible if ~nonzero(X) & C != 0):
	Use with_known_nonzero_bits@0 instead of
	(with_certain_nonzero_bits2 @1), use with_possible_nonzero_bits@0
	instead of (with_possible_nonzero_bits2 @0) and
	get_known_nonzero_bits (@1) instead of wi::to_wide (@1).

	* gcc.dg/tree-ssa/pr117420.c: New test.