[GCC, ARM] Backport trunk fix to 4.8 branch to properly handle rtx of ARM PLD instruction

Richard Earnshaw rearnsha@arm.com
Wed Jan 15 16:40:00 GMT 2014


On 15/01/14 15:59, Terry Guo wrote:
> 
> 
>> -----Original Message-----
>> From: Richard Earnshaw
>> Sent: Wednesday, January 15, 2014 10:30 PM
>> To: Terry Guo
>> Cc: gcc-patches@gcc.gnu.org
>> Subject: Re: [GCC, ARM] Backport trunk fix to 4.8 branch to properly
> handle
>> rtx of ARM PLD instruction
>>
>> On 15/01/14 12:37, Terry Guo wrote:
>>>
>>>
>>>> -----Original Message-----
>>>> From: Terry Guo [mailto:terry.guo@arm.com]
>>>> Sent: Wednesday, January 15, 2014 8:21 PM
>>>> To: Richard Earnshaw
>>>> Cc: gcc-patches@gcc.gnu.org
>>>> Subject: RE: [GCC, ARM] Backport trunk fix to 4.8 branch to properly
>>> handle
>>>> rtx of ARM PLD instruction
>>>>
>>>>>
>>>>> Preferably, particularly since you haven't supplied a testcase.
>>>>>
>>>>> R.
>>>>
>>>> Bug is reported at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59826.
>>>> I
>>> shall
>>>> update the patch to include the test case.
>>>>
>>>> BR,
>>>> Terry
>>>
>>> Here is updated patch along with test case. Is it OK?
>>>
>>
>> I'm rather concerned about the complexity of this patch as a backport.
>> Furthermore, part of the problem is that the preload insn is misclassified
> as
>> an alu_reg operation, which it clearly isn't.
>>
>> Instead of doing this, please could you try a simpler patch that simply
>> reclassifies the "type" of preload as "load1".  This would break the
>> alu->load/store dependency and thereby avoid the trigger of the problem
>>
>> R.
> 
> Thanks Richard and you are right. What you said should be the root cause for
> this issue. I will implement another patch for trunk to correctly classify
> the preload instruction into load1, and then back port to 4.8 branch.
> Therefore please consider my request in this thread discarded.
> 

Trunk has already reclassified it this way.

R.




More information about the Gcc-patches mailing list