Re: [PATCH] Loop Overflow Bug Fix

["Soni L." <fakedme@...>]

On 2017-11-15 11:18 PM, Paige DePol wrote:
> Soni L. <fakedme@gmail.com> wrote:
>
> > On 2017-11-15 08:34 PM, Paige DePol wrote:
> > > Sorry for the noise... I meant to upload an optimised version of the patch
> > > with the last post to this list! :[
> > >
> > > The patch attached to this post has a small optimisation vs the previously
> > > posted patch; the limit check has simply been replaced with the step size
> > > check. This can be done as a limit bounds check is added to OP_FORPREP with
> > > the patch to check if the loop should iterate at all. This new step size
> > > check simply adds one numeric subtraction each loop iteration, well, and a
> > > negation of 'step' for loops with negative step values.
> > >
> > > Again, sorry for the noise, this should be the final patch in relation to
> > > fixing the 'for' loop overflows in Lua... hopefully! ;)
> > >
> > > ~Paige
> > What happens if you use excessively large loop steps?
> Like this?
>
>
> local reps = 0
> for i=math.mininteger,math.maxinteger,math.maxinteger do reps = reps + 1 end
> assert(reps == 1)

Shouldn't this run 3 times, once for i=math.mininteger, once for i=-1, 
once for i=math.maxinteger-1?
Or do for loops not work as I thought they did?

> reps = 0
> for i=math.maxinteger,math.mininteger,-math.maxinteger do reps = reps + 1 end
> assert(reps == 1)

Idk about this one but it may be wrong too.

> reps = 0
> for i=math.mininteger,math.maxinteger,math.maxinteger/2 do reps = reps + 1 end
> assert(reps == 5)

I have absolutely NO IDEA on this one.

> reps = 0
> for i=math.maxinteger,math.mininteger,-math.maxinteger/2 do reps = reps + 1 end
> assert(reps == 5)

I have absolutely NO IDEA on this one either.

> All works as expected! :)
>
> ~Paige

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