[Gambas-user] JIT bug 4

[Emil Lenngren]

Because if you only write "x = 0.6 ^ x", that statement is completely
optimized away, because x is never used later on.
If you write "Print 0.6 ^ x", the result of the operation is printed, i.e.
used.

If you write "Print 0.6 ^ 2", that is optimized to "Print 0.36".

/Emil

2012/7/10 Jussi Lahtinen <jussi.lahtinen at ...626...>

> Yes it works now.
> But "Print 0.6 ^ x" did crash, but "x = 0.6 ^ x" alone did not crash
> ("imMatr[10, 10] += x" was needed)!
> So I wonder was "0.6 ^ x" culprit alone?
>
> Jussi
>
>
>
>
> On 10 July 2012 18:13, Emil Lenngren <emil.lenngren at ...626...> wrote:
>
> > It should work now in revision #4934!
> >
> > /Emil
> >
> > 2012/7/9 Emil Lenngren <emil.lenngren at ...626...>
> >
> > > From gdb I disassemble the jit function to this:
> > > ...
> > >    0x00007ffff7e3f05c:  movabs $0x0,%rax
> > >    0x00007ffff7e3f066:  callq  *%rax
> > > ...
> > >
> > > You can see that llvm replaced the llvm.powi.f64 to a null function :/
> > >
> > > 2012/7/9 Emil Lenngren <emil.lenngren at ...626...>
> > >
> > >> Public Sub Button1_Click()
> > >>   test(19)
> > >> End
> > >>
> > >>
> > >> Fast Private Sub test(x As Integer)
> > >>   Print 0.6 ^ x
> > >> End
> > >>
> > >> Does this crash for you as well?
> > >>
> > >> I think there is a bug in llvm or something. It doesn't seem to like
> > that
> > >> I call llvm.powi.f64.
> > >>
> > >> I shall see what I can do about it ...
> > >>
> > >> /Emil
> > >>
> > >> 2012/7/9 Jussi Lahtinen <jussi.lahtinen at ...626...>
> > >>
> > >>> In fact the function can be further reduced to:
> > >>> c = CInt((0.6 ^ iEta) / sngCached[iEta])
> > >>>
> > >>> Jussi
> > >>>
> > >>>
> > >>>
> > >>> On 9 July 2012 21:02, Jussi Lahtinen <jussi.lahtinen at ...626...>
> wrote:
> > >>>
> > >>> > Finally, here it is isolated. See attachment.
> > >>> > I don't know why I didn't get it in first try, and yet, I'm not
> sure
> > >>> what
> > >>> > is going on...
> > >>> >
> > >>> > Gambas 3 rev 4921 @ Xubuntu 12.04 64bit
> > >>> >
> > >>> > Jussi
> > >>> >
> > >>>
> > >>>
> >
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