re PR target/52496 (avr-specific built-ins missing memory barrier)

re PR target/52496 (avr-specific built-ins missing memory barrier)

	PR target/52496
	* config/avr/avr.c (avr_mem_clobber): New static function.
	(avr_expand_delay_cycles): Add memory clobber operand to
	delay_cycles_1, delay_cycles_2, delay_cycles_3, delay_cycles_4.
	* config/avr/avr.md (unspec): Add UNSPEC_MEMORY_BARRIER.
	(enable_interrupt, disable_interrupt): New expander.
	(nopv, sleep, wdr): New expanders.
	(delay_cycles_1): Add memory clobber.
	(delay_cycles_2): Add memory clobber.
	(delay_cycles_3): Add memory clobber.
	(delay_cycles_4): Add memory clobber.
	(cli_sei): New insn from former "enable_interrupt",
	"disable_interrupt" with memory clobber.
	(*wdt): New insn from former "wdt" with memory clobber.
	(*nopv): Similar, but for "nopv".
	(*sleep): Similar, but for "sleep".

From-SVN: r185100