Handle PHIs in compute_objsize.

Handle PHIs in compute_objsize.

PR middle-end/92936 - missing warning on a past-the-end store to a PHI
PR middle-end/92940 - incorrect offset and size in -Wstringop-overflow for out-of-bounds store into VLA and two offset ranges
PR middle-end/89428 - missing -Wstringop-overflow on a PHI with variable offset

gcc/ChangeLog:

	PR middle-end/92936
	PR middle-end/92940
	PR middle-end/89428
	* builtins.c (access_ref::access_ref): Initialize member.
	(access_ref::phi): New function.
	(access_ref::get_ref): New function.
	(access_ref::add_offset): Remove duplicate assignment.
	(maybe_warn_for_bound): Add "maybe" kind of warning messages.
	(warn_for_access): Same.
	(inform_access): Rename...
	(access_ref::inform_access): ...to this.  Print PHI arguments.  Format
	offset the same as size and simplify.  Improve printing of allocation
	functions and VLAs.
	(check_access): Adjust to the above.
	(gimple_parm_array_size): Change argument.
	(handle_min_max_size): New function.
	* builtins.h (class ssa_name_limit_t): Move class here from
	tree-ssa-strlen.c.
	(struct access_ref): Declare new members.
	(gimple_parm_array_size): Change argument.
	* tree-ssa-strlen.c (maybe_warn_overflow): Use access_ref and simplify.
	(handle_builtin_memcpy): Correct argument passed to maybe_warn_overflow.
	(handle_builtin_memset): Same.
	(class ssa_name_limit_t): Move class to builtins.{h,c}.

gcc/testsuite/ChangeLog:

	PR middle-end/92936
	PR middle-end/92940
	PR middle-end/89428
	* c-c++-common/Wstringop-overflow-2.c: Adjust text of expected
	informational notes.
	* g++.dg/warn/Wstringop-overflow-3.C: Same.
	* g++.dg/warn/Wplacement-new-size.C: Remove a test for a no longer
	issued warning.
	* gcc.dg/Warray-bounds-43.c: Removed unused declarations.
	* gcc.dg/Wstringop-overflow-11.c: Remove xfails.
	* gcc.dg/Wstringop-overflow-12.c: Same.
	* gcc.dg/Wstringop-overflow-17.c: Adjust text of expected messages.
	* gcc.dg/Wstringop-overflow-27.c: Same.  Remove xfails.
	* gcc.dg/Wstringop-overflow-28.c: Adjust text of expected messages.
	* gcc.dg/Wstringop-overflow-29.c: Same.
	* gcc.dg/Wstringop-overflow-37.c: Same.
	* gcc.dg/Wstringop-overflow-46.c: Same.
	* gcc.dg/Wstringop-overflow-47.c: Same.
	* gcc.dg/Wstringop-overflow-54.c: Same.
	* gcc.dg/warn-strnlen-no-nul.c: Add expected warning.
	* gcc.dg/Wstringop-overflow-7.c: New test.
	* gcc.dg/Wstringop-overflow-58.c: New test.
	* gcc.dg/Wstringop-overflow-59.c: New test.
	* gcc.dg/Wstringop-overflow-60.c: New test.
	* gcc.dg/Wstringop-overflow-61.c: New test.
	* gcc.dg/Wstringop-overflow-62.c: New test.
	* gcc.dg/Wstringop-overflow-63.c: New test.
	* gcc.dg/Wstringop-overflow-64.c: New test.