int main() { asm volatile ( "clr r25\n" "ldi r24, %0\n" :: "M" ((unsigned char)137) ); }
asm.c:4:5: warning: asm operand 0 probably doesn't match constraints
asm volatile (
^
asm.c:4:5: error: impossible constraint in 'asm'
Tested with avr-gcc 5.4.0 and 8.4.0. If I make the constant less than 128, there is no error. The docs for the "M" constraint say:
8-bit integer constant | 0 to 255 |
https://www.nongnu.org/avr-libc/...