Bug of gas (binutils-2.9.1.0.23): Wrong code for SETHI on SPARC
H.J. Lu
hjl@lucon.org
Fri Apr 2 16:42:00 GMT 1999
>
> From: hjl@lucon.org (H.J. Lu)
> Date: Fri, 2 Apr 1999 16:10:48 -0800 (PST)
>
> > gas out of binutils-2.9.1.0.23 (and older versions) has a severe bug
> > for the SPARC platform (sparc-sun-solaris2.6), i.e. it generates
> > wrong code for
> >
> > sethi 0x4000,%i0
> >
> > (and probably in all other cases where sethi is used without the
> > %hi(...)-construct).
> >
> > The sethi instruction has following suggested assembly syntax
> > (see SPARC Architecture Manual):
> >
> > sethi const22,reg
> >
> > const22 is a 22-bit constant that is placed by sethi in the most
> > significant 22 bits of reg (while it zeroes the 10 least significant
> > bits of reg). Therefore we would expect the value 0x100000 in %i0
> > after the execution of ``sethi 16384''. Instead of this, gas
> > modifies the given constant such that 0x4000 will be found in %i0
> > afterwards. This would have been equivalent to
> >
> > sethi %hi(0x4000),%i0
>
> Here is a new patch. Please discard my last patch to tc-sparc.c.
> Let me know what you get.
>
> Thanks.
>
>
> H.J.
> ---
> Fri Apr 2 16:05:25 1999 H.J. Lu (hjl@gnu.org)
>
> * sparc-opc.c: Change "sethi" from "h,d" to "n,d".
>
> I don't think that can be right. I think it will do the wrong thing
> for
> sethi foo,%i0
>
You are right. That shows I know nothing about Sparc. Do you have
a fix for the bug?
Thanks.
--
H.J. Lu (hjl@gnu.org)
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