Re: [sdcc-devel] Adding new token - will all ports have to be modified at once?

[Maarten B. <sou...@ds...>]

Philipp,

> I looked at different port's gen.c; some do arithmetic right shifts for
> signed operands (pic16), some do logical shifts for both (z80), so I
> assumed RIGHT_OP was undefined for signed left operands.
> According to the  C99 standard x >> y is implementation-defined for x <=
 0
> (x << y is undefined for x < 0).

I was not aware of that.

> If there's a processor where logical shifts are faster than arithmetic
> shifts, it would make sense to have different tokens, so arithmetic
> shifts would be needed only to replace divisions.

I would vote to make all ports always use an arithmetic shift for signed
operands. If the user wants the faster logical shift he should use
unsigned operands.

Maarten