2008/6/7 Uros Bizjak <[EMAIL PROTECTED]>: > Hello! > >> The 16bit target that i am porting to gcc4.1.2 doesn't have any >> instructions for 32bit operations. But for addition and subtraction >> there is >> addc >> subc >> instructions that consider carry bit also. Presently i have patterns >> for SImode addition and subtraction such that the template will have >> >> add %0, %1\naddc %N0, %N1 >> sub %0, %1\nsubc %N0, %N1 >> >> Will it be possible for me to write separate patterns for the >> instructions add and addc? >> > > You can look into config/i386.md, how i.e. adddi3 is expanded and split in > case of !TARGET_64BIT.
But is it scheduling safe? I mean you can't have addc executed before add. If i am right there will be no dependency between the two instructions. So there can be a case where addc gets scheduled before add. Am i right on both counts? Regards, Shafi
