PR libstdc++/54924 - Warn for std::string constructor with wrong size

PR libstdc++/54924 - Warn for std::string constructor with wrong size
PR middle-end/79234 - warn on past the end reads by library functions

gcc/ChangeLog:

	PR middle-end/79234
	* builtins.c (check_sizes): Adjust to handle reading past the end.
	Avoid printing excessive upper bound of ranges.  Use %E to print
	tree nodes instead of converting them to %wu.
	(expand_builtin_memchr): New function.
	(compute_dest_size): Rename...
	(compute_objsize): ...to this.
	(expand_builtin_memcpy): Adjust.
	(expand_builtin_mempcpy): Adjust.
	(expand_builtin_strcat): Adjust.
	(expand_builtin_strcpy): Adjust.
	(check_strncat_sizes): Adjust.
	(expand_builtin_strncat): Adjust.
	(expand_builtin_strncpy): Adjust and simplify.
	(expand_builtin_memset): Adjust.
	(expand_builtin_bzero): Adjust.
	(expand_builtin_memcmp): Adjust.
	(expand_builtin): Handle memcmp.
	(maybe_emit_chk_warning): Check strncat just once.

gcc/testsuite/ChangeLog:

	PR middle-end/79234
	* gcc.dg/builtin-stringop-chk-8.c: New test.
	* gcc.dg/builtin-stringop-chk-1.c: Adjust.
	* gcc.dg/builtin-stringop-chk-4.c: Same.
	* gcc.dg/builtin-strncat-chk-1.c: Same.
	* g++.dg/ext/strncpy-chk1.C: Same.
	* g++.dg/torture/Wsizeof-pointer-memaccess1.C: Same.
	* gcc.dg/out-of-bounds-1.c: Same.
	* gcc.dg/pr78138.c: Same.
	* gcc.dg/torture/Wsizeof-pointer-memaccess1.c: Same.
	* gfortran.dg/mvbits_7.f90: Same.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@247622 138bc75d-0d04-0410-961f-82ee72b054a4