re PR target/43746 (-fmerge-constants and -fmerge-all-constants don't work at AVR...

re PR target/43746 (-fmerge-constants and -fmerge-all-constants don't work at AVR target)

gcc/
	PR target/43746
	* config/avr/avr.c (AVR_SECTION_PROGMEM): New Define.
	(progmem_section): New Variable.
	(avr_asm_init_sections): Initialize it.
	(TARGET_ASM_SELECT_SECTION): Define to...
	(avr_asm_select_section): ... this new Function.
	(avr_replace_prefix): New Function.
	(avr_asm_function_rodata_section): Use it.
	(avr_insert_attributes): Don't add section attribute for PROGMEM.
	(avr_section_type_flags): Use avr_progmem_p instead of section
	name to detect if object is in PROGMEM.
	(avr_asm_named_section): Set section name prefix for objects in
	PROGMEM.

testsuite/
	PR target/43746
	* testsuite/gcc.target/avr/torture/avr-torture.exp
	(AVR_TORTURE_OPTIONS): Add test cases "-O2 -fdata-sections" and
	"-O2 -fmerge-all-constants".

From-SVN: r178779