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Re: [PATCH, ARM, PR64208] LRA ICE Fix
- From: Yvan Roux <yvan dot roux at linaro dot org>
- To: xxingpan at marvell dot com
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Ramana Radhakrishnan <Ramana dot Radhakrishnan at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Vladimir Makarov <vmakarov at redhat dot com>
- Date: Fri, 27 Mar 2015 11:12:05 +0100
- Subject: Re: [PATCH, ARM, PR64208] LRA ICE Fix
- Authentication-results: sourceware.org; auth=none
- References: <CAD57uCfHZuBqWbMiqGT+qDXQj37NCa9wKcEN+RpcUS3xpurYhQ at mail dot gmail dot com> <CAJA7tRZpRKLQ=FWrnSs8x-=j_ObrzyAxBWkMckqHmkrdp2M-GQ at mail dot gmail dot com> <CAD57uCfdfpcuDrW7ZkG8J6Ew8-F7J3xMYxwakTJYDB52s9pt5A at mail dot gmail dot com>
Hi Xingxing,
do you know if it is possible to test this patch inside Marvell (as it
is a fix for iWMMXT arch.) ?
Thanks a lot
Yvan
On 23 March 2015 at 18:47, Yvan Roux <yvan.roux@linaro.org> wrote:
> Hi,
>
> On 23 March 2015 at 17:08, Ramana Radhakrishnan
> <ramana.gcc@googlemail.com> wrote:
>> On Wed, Mar 18, 2015 at 10:19 AM, Yvan Roux <yvan.roux@linaro.org> wrote:
>>> Hi,
>>>
>>> This is a fix for PR64208 where LRA loops when dealing with
>>> iwmmxt_arm_movdi insn. As explain in the PR, the issue was introduced
>>> on trunk and 4.9 branch by fix of PR rtl-optimization/60969 and then
>>> workaround by r211798 (-fuse-caller-save enable for ARM).
>>>
>>> The changes in IRA cost made by PR60969, changed the register class of
>>> this insn output from GENERAL_REGS to IWMMXT_REGS, and the
>>> redundancies in the insn pattern alternatives description force LRA to
>>> reload the pseudo, which generates the same iwmmxt_arm_movdi insn,
>>> which can't be resolved, and so on ...
>>>
>>> Removing the redundancies fixes the issue, as LRA find that
>>> alternative 8 (Uy => y) matches.
>>>
>>> This issue is present in 4.9 branch, but latent on trunk (the
>>> clobbering of IP and CC information added during -fuse-caller-save
>>> patch changed the register allocation).
>>>
>>> Cross compiled and regression tested on ARM targets (but not on an
>>> IWMMXT one), is it ok for trunk and 4.9 branch ?
>>
>>
>> This looks sane. It doesn't look reasonable for alternatives to be
>> duplicating each other.
>>
>> Given I have neither the time nor the hardware to test this patch on,
>> I'd rather someone with an interest in iwMMX possibly folks from
>> Marvell can pick up testing for this patch.
>
> Ok, Thanks Ramana, I'll wait for somebody able to test it. Notice,
> that without this patch on the 4.9 branch, building a cross compiler
> which default to iWMMXT architectures ICE on that during LRA while
> building of libgcc.
>
> Cheers,
> Yvan
>
>> regards
>> Ramana
>>
>>>
>>> Rq: I think that adding IP and CC clobbers to
>>> CALL_INSN_FUNCTION_USAGE, as specified by AAPCS, in 4.9 branch is
>>> something we need too, I've a patch for that if you agree on that.
>>>
>>> Thanks,
>>> Yvan
>>>
>>> 2105-03-17 Yvan Roux <yvan.roux@linaro.org>
>>>
>>> PR target/64208
>>> * config/arm/iwmmxt.md ("*iwmmxt_arm_movdi"): Cleanup redundant
>>> alternatives.