Re: [PATCH, MIPS] fix MIPS16 jump table overflow

[Sandra Loosemore <sandra at codesourcery dot com>]

On 08/24/2012 11:46 PM, Richard Sandiford wrote:
> Andrew Pinski<pinskia@gmail.com>  writes:
> > On Fri, Aug 24, 2012 at 10:08 PM, Andrew Pinski<pinskia@gmail.com>  wrote:
> > > On Wed, Aug 22, 2012 at 7:15 PM, Sandra Loosemore
> > > <sandra@codesourcery.com>  wrote:
> > > > On 08/21/2012 02:23 PM, Richard Sandiford wrote:
> > > > > Would be nice to add a compile test for -mabi=64 just to make sure
> > > > > that Pmode == DImode works.  A copy of an existing test like
> > > > > code-readable-1.c would be fine.
> > > >
> > > >
> > > > I'm having problems with this part -- it seems like every combination of
> > > > options with -mabi=64 I've tried with code-readable-1.c complains about
> > > > something-or-another being incompatible.  The closest I've come is "-mabi=64
> > > > -march=mips64 -msoft-float", which is accepted by the mipsisa32r2-sde-elf
> > >
> > > Did you test this at all on a mips64-*-* target?  After this change
> > > n64 jump tables are broken.
> > > Before CASE_VECTOR_MODE was DImode for n64 .
> > >
> > > See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54371 for why it fails.
> > > gpdword produces a double word for n64.
> > >
> > > For EABI64 it is ok to load 32bits because that the addresses are
> > > 32bits but for n64, it is not ok.  The load addresses are normally
> > > above the 32bits boundary.
> >
> > I am testing a patch which changes CASE_VECTOR_MODE to be:
> > #define CASE_VECTOR_MODE ((mips_abi == ABI_64) ? DImode : SImode)
>
> I think it should be:
>
> #define CASE_VECTOR_MODE \
>    (TARGET_MIPS16_SHORT_JUMP_TABLES ? SImode : ptr_mode)
>
> #define CASE_VECTOR_SHORTEN_MODE(MIN, MAX, BODY) \
>    (!TARGET_MIPS16_SHORT_JUMP_TABLES ? ptr_mode \
>     : (MIN)>= -32768&&  (MAX)<  32768 : HImode \
>     : SImode)
>
> The point being that the TARGET_MIPS16_SHORT_JUMP_TABLES entries
> are relative, so SImode would be correct there even for n64.
>
> I'd missed that CASE_VECTOR_MODE applied to tablejump as well
> as casesi, sorry.

Yeah, sorry.  :-(  The original version of the patch I posted (where 
CASE_VECTOR_MODE was #defined to ptr_mode) had indeed been tested on 
mips64, but not the revised version that was approved for check-in.

-Sandra