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Re: [GCC, ARM] Backport trunk fix to 4.8 branch to properly handle rtx of ARM PLD instruction
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Terry Guo <Terry dot Guo at arm dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 15 Jan 2014 14:30:22 +0000
- Subject: Re: [GCC, ARM] Backport trunk fix to 4.8 branch to properly handle rtx of ARM PLD instruction
- Authentication-results: sourceware.org; auth=none
- References: <000001cf11d3$71478d40$53d6a7c0$ at arm dot com> <52D65AC2 dot 8000704 at arm dot com> <000001cf11de$f6249c00$e26dd400$ at arm dot com> <52D67204 dot 50504 at arm dot com> <000201cf11ee$900a8190$b01f84b0$ at arm dot com>
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.