Re: [Tinycc-devel] [PATCH] tccgen.c: Optimise 0<<x, 0>>x, -1>>x, x&0, x*0, x|-1, x%1.

[Edmund Grimley Evans]

Vincent Lefevre <address@hidden>:

> > Do not optimise (0 / x) and (0 % x) here as x might be zero, though
> > for an architecture that does not generate an exception for division
> > by zero the back end might choose to optimise those.
> 
> When x is 0, this is undefined behavior, so that you are free to
> optimize them, even if the architecture generates an exception for
> division by 0. Contrary to IEEE 754, there isn't any requirement
> to generate an exception for integer operations.

Yes, I know, but I would nevertheless prefer (0 / x) to do the same
thing as (y / x) when both x and y are zero at run time. That
potentially depends on the target architecture.

Edmund