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

[Richard Sandiford <rdsandiford@googlemail.com>]

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.

Richard