hppa: Implement TARGET_ATOMIC_ASSIGN_EXPAND_FENV

hppa: Implement TARGET_ATOMIC_ASSIGN_EXPAND_FENV

This change implements __builtin_get_fpsr() and __builtin_set_fpsr(x)
to get and set the floating-point status register.  They are used to
implement pa_atomic_assign_expand_fenv().

2024-02-02  John David Anglin  <danglin@gcc.gnu.org>

gcc/ChangeLog:

	PR target/59778
	* config/pa/pa.cc (enum pa_builtins): Add PA_BUILTIN_GET_FPSR
	and PA_BUILTIN_SET_FPSR builtins.
	* (pa_builtins_icode): Declare.
	* (def_builtin, pa_fpu_init_builtins): New.
	* (pa_init_builtins): Initialize FPU builtins.
	* (pa_builtin_decl, pa_expand_builtin_1): New.
	* (pa_expand_builtin): Handle PA_BUILTIN_GET_FPSR and
	PA_BUILTIN_SET_FPSR builtins.
	* (pa_atomic_assign_expand_fenv): New.
	* config/pa/pa.md (UNSPECV_GET_FPSR, UNSPECV_SET_FPSR): New
	UNSPECV constants.
	(get_fpsr, put_fpsr): New expanders.
	(get_fpsr_32, get_fpsr_64, set_fpsr_32, set_fpsr_64): New
	insn patterns.