re PR target/78093 ([avr] New variable attribute "absdata" and option "-mabsdata" to enable LDS / STS on Reduced Tiny)

gcc/
	PR target/78093
	* doc/extend.texi (AVR Variable Attributes) [absdata]: Document it.
	* config/avr/avr.c (AVR_SYMBOL_FLAG_TINY_ABSDATA): New macro.
	(avr_address_tiny_absdata_p): New static function.
	(avr_legitimate_address_p, avr_legitimize_address) [AVR_TINY]: Use
	it to determine validity of constant addresses.
	(avr_attribute_table) [absdata]: New variable attribute...
	(avr_handle_absdata_attribute): ...and handler.
	(avr_decl_absdata_p): New static function.
	(avr_encode_section_info) [AVR_TINY]: Use it to add flag
	AVR_SYMBOL_FLAG_TINY_ABSDATA to respective symbols_refs.
	(avr_address_cost) [AVR_TINY]: absdata addresses cost 2.
gcc/testsuite/
	PR target/78093
	* lib/target-supports.exp (check_effective_target_avr_tiny): New proc.
	* gcc.target/avr/torture/tiny-absdata-1.c: New test.

From-SVN: r241468