Re: sign-extending smaller modes

[Geoff Keating <geoffk at cygnus dot com>]

> cc: dj@delorie.com, gcc-patches@gcc.gnu.org
> Reply-To: law@cygnus.com
> Date: Tue, 08 Aug 2000 13:35:50 -0600
> From: Jeffrey A Law <law@cygnus.com>
> 
>   In message <200008081927.MAA05109@localhost.cygnus.com>you write:
>    > Jeffrey A Law <law@cygnus.com> writes:
>   > 
>   > > Interestingly enough, if I install your change I can't bootstrap the
>   > > PA port, so there's something happening that we don't quite understand.
>   > 
>   > I suspect this is a bug somewhere else.  One of the structural
>   > problems with gcc is that it doesn't make a proper distinction between
>   > arithmetic on the host and arithmetic on the target for integer
>   > values.  This causes lots and lots of problems whenever they differ.
> It was a *native* build.  The stage1 compiler mis-compiles the stage2

Well, included in my above statement is that 'arithmetic on the host'
means HOST_WIDE_INT, but 'arithmetic on the target' happens in some
particular mode which may or may not be the same as HOST_WIDE_INT.
In the case of the PA, which has SImode and DImode, one of them is
guaranteed to be different to HOST_WIDE_INT.

> compiler which causes the stage2 compiler to bogusly trigger an
> enable-checking failure in the C++ front-end.

Perhaps some problem in the PA's extensive bitfield operations?
I guess now someone has to actually debug it.  Do you have a PA
machine available?

-- 
- Geoffrey Keating <geoffk@cygnus.com>