RFA: patch to fix PR55116

[H.J. Lu]

On Mon, Oct 29, 2012 at 4:41 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Mon, Oct 29, 2012 at 9:38 AM, Vladimir Makarov <vmakarov@redhat.com> wrote:
>> On 12-10-29 12:21 PM, Richard Sandiford wrote:
>>>
>>> Vladimir Makarov <vmakarov@redhat.com> writes:
>>>>
>>>>     H.J. in
>>>>
>>>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55116
>>>>
>>>>     reported an interesting address
>>>>
>>>> (and:DI (subreg:DI (plus:SI (ashift:SI (reg:SI 96 [ glob_vol_int.22 ])
>>>>                   (const_int 2 [0x2]))
>>>>               (symbol_ref:SI ("glob_vol_int_arr") <var_decl
>>>> 0x7ffff03c2720 glob_vol_int_arr>)) 0)
>>>>       (const_int 4294967295 [0xffffffff]))
>>>>
>>>>     which can not be correctly extracted.  Here `and' with `subreg'
>>>> behaves as an address mutation.
>>>>
>>>>     The following patch fixes the problem.
>>>>
>>>> Ok to commit, Richard?
>>>
>>> Heh, I wondered if subregs might still be used like that, and was almost
>>> tempted to add them just in case.
>>>
>>> I think this particular case is really a failed canonicalisation and that:
>>>
>>>     (and:DI (subreg:DI (foo:SI ...) 0) (const_int 0xffffffff))
>>>
>>> ought to be:
>>>
>>>     (zero_extend:DI (foo:SI ...))
>>
>> Yes, that was my thought too.
>>
>>> But I know I've approved MIPS patches to accept
>>> (and:DI ... (const_int 0xffffffff)) as an alternative.
>>>
>>>> Index: rtlanal.c
>>>> ===================================================================
>>>> --- rtlanal.c   (revision 192942)
>>>> +++ rtlanal.c   (working copy)
>>>> @@ -5459,6 +5459,11 @@ strip_address_mutations (rtx *loc, enum
>>>>          else if (code == AND && CONST_INT_P (XEXP (*loc, 1)))
>>>>           /* (and ... (const_int -X)) is used to align to X bytes.  */
>>>>           loc = &XEXP (*loc, 0);
>>>> +      else if (code == SUBREG
>>>> +              && ! REG_P (XEXP (*loc, 0)) && ! MEM_P (XEXP (*loc, 0)))
>>>> +       /* (subreg (operator ...) ...) usually inside and is used for
>>>> +          mode conversion too.  */
>>>> +       loc = &XEXP (*loc, 0);
>>>
>>> I think the condition should be:
>>>
>>>        else if (code == SUBREG
>>>                 && !OBJECT_P (SUBREG_REG (*loc))
>>>                 && subreg_lowpart (*loc))
>>>
>>> OK with that change, if it works.
>>>
>> Yes, it works.
>> I've submitted the following patch.
>>
>
> It doesn't work right.  I will create a new testcase.
>

I uploaded a tectase to

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55116

-- 
H.J.