This is just a small addendum to the option and specs handling:

- Document new avr-gcc command options

- Change -march= to -mmcu= in some test cases

- Add comfigure test to detect whether gas supports -mrmw and --mlink-relax.

- Use result of these tests in specs generatio, i.e. omit respective options if 
they are not supported.


Ok to apply?


Two issues remain:

- The tests that add -mmcu= to the command options will fail because there must 
not be more than one -mmcu=.  Supporting several, incompatible MCUs makes no 
sense (same for incompatible -march + -mmcu which was the case).  In 4.9 this 
works per accident with unspecified definitions for built-in macros or when the 
options differ in default settings, for example.

- Spaces in the installation path are not supported.  It's possible to recover 
from spaces in -specs= by escaping them in spec function device-specs-file. 
However this is almost impossible for the device library without changing gcc.c 
which can use convert_white_space() as needed.  Adding more than one escape 
level is not possible because the '\' would be interpreted as part of the path.


Johann


gcc/
	PR target/65296
	* configure.ac [avr]: Check as for options -mrmw, --mlink-relax.
	* configure: Regenerate.
	* config.in: Regenerate.
	* config/avr/gen-avr-mmcu-specs.c (config.h): Include it.
	(*asm_relax): Only define spec if HAVE_AS_AVR_MLINK_RELAX_OPTION.
	(*asm_rmw): Only define spec if HAVE_AS_AVR_MRMW_OPTION.


gcc/
	PR target/65296
	* doc/invoke.texi (AVR Options) [-mrmw]: Document it.
	[-mn-flash]: Document it.
	[__AVR_DEVICE_NAME__]: Document it.
	[__ARV_ARCH__]: Document avrtiny.

gcc/testsuite/
	PR target/65296
	* gcc.target/avr/tiny-memx: Use -mmcu instead of -march.
	* gcc.target/avr/tiny-caller-save.c: Same.


gcc/
	PR target/65296
	* configure.ac [avr]: Check as for option -mrmw.
	* configure: Regenerate.
	* config.in: Regenerate.
	* config/avr/driver-avr.c (avr_device_to_as): Don't add -mrmw to
	assembler options if not HAVE_AS_AVR_MRMW_OPTION.