From: Kyrill Tkachov <kyrylo.tkachov@arm.com>
To: Shiva Chen <shiva0217@gmail.com>
Cc: Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
GCC Patches <gcc-patches@gcc.gnu.org>,
"nickc@redhat.com" <nickc@redhat.com>,
Richard Earnshaw <Richard.Earnshaw@arm.com>,
"shivac@marvell.com" <shivac@marvell.com>
Subject: Re: [GCC, ARM] armv8 linux toolchain asan testcase fail due to stl missing conditional code
Date: Thu, 04 Jun 2015 08:24:00 -0000 [thread overview]
Message-ID: <5570097C.2010706@arm.com> (raw)
In-Reply-To: <CAH=PD7aXefCqHB0kbz7kH0LVEKwJGM8kp5-U7RxZ61x-b-Xv6w@mail.gmail.com>
Hi Shiva,
On 04/06/15 04:13, Shiva Chen wrote:
> Hi, Ramana
>
> Currently, I work for Marvell and the company have copyright assignment on file.
>
> Hi, all
>
> After adding the attribute and rebuild gcc, I got the assembler error message
>
> load_n.s:39: Error: bad instruction `ldrbeq r0,[r0]'
>
> When i look into armv8 ISA document, it seems ldrb Encoding A1 have
> conditional code field.
>
> Does it mean we should also patch assembler or I just miss
> understanding something ?
>
> Following command use to generate load_n.s:
>
> /home/shivac/build-system-trunk/Release/build/armv8-marvell-linux-gnueabihf-hard/gcc-final/./gcc/cc1
> -fpreprocessed load_n.i -quiet -dumpbase load_n.c -march=armv8-a
> -mfloat-abi=hard -mfpu=fp-armv8 -mtls-dialect=gnu -auxbase-strip
> .libs/load_1_.o -g3 -O2 -Wall -Werror -version -fPIC -funwind-tables
> -o load_n.s
>
>
> The test.c is a simple test case to reproduce missing conditional code
> in mmap.c.
>
> Any suggestion ?
I reproduced the assembler failure with your patch.
The reason is that for arm mode we use divided syntax, where the condition field goes in a
different place. So, while ldrbeq r0,[r0] is rejected, ldreqb r0, [r0] works.
Since we always use divided syntax for arm mode, I think you'll need to put the condition field
in the right place depending on arm or thumb mode.
Ugh, this is becoming ugly :(
Kyrill
>
>
> Shiva
>
> 2015-06-03 17:29 GMT+08:00 Shiva Chen <shiva0217@gmail.com>:
>> Hi, Ramana
>>
>> I'm not sure what copyright assignment means ?
>>
>> Does it mean the patch have copyright assignment or not ?
>>
>> I update the patch to add "predicable" and "predicable_short_it"
>> attribute as suggestion.
>>
>> However, I don't have svn write access yet.
>>
>> Shiva
>>
>> 2015-06-03 16:36 GMT+08:00 Kyrill Tkachov <kyrylo.tkachov@arm.com>:
>>> On 03/06/15 09:32, Ramana Radhakrishnan wrote:
>>>>> This pattern is not predicable though, i.e. it doesn't have the
>>>>> "predicable" attribute set to "yes".
>>>>> Therefore the compiler should be trying to branch around here rather than
>>>>> try to do a cond_exec.
>>>>> Why does the generated code above look like it's converted to conditional
>>>>> execution?
>>>>> Could you produce a self-contained reduced testcase for this?
>>>> CCFSM state machine in ARM state.
>>>>
>>>> arm.c (final_prescan_insn).
>>>
>>> Ah ok.
>>> This patch makes sense then.
>>> As Ramana mentioned, please mark the pattern with "predicable" and also set
>>> the "predicable_short_it" attribute to "no" so that it will not be
>>> conditionalised in Thumb2 mode or when -mrestrict-it is enabled.
>>>
>>> Thanks,
>>> Kyrill
>>>
>>>
>>>
>>>> Ramana
>>>>
>>>>> Thanks,
>>>>> Kyrill
>>>>>
>>>>>> @@ -91,9 +91,9 @@
>>>>>> {
>>>>>> enum memmodel model = memmodel_from_int (INTVAL (operands[2]));
>>>>>> if (is_mm_relaxed (model) || is_mm_consume (model) ||
>>>>>> is_mm_acquire (model))
>>>>>> - return \"str<sync_sfx>\t%1, %0\";
>>>>>> + return \"str<sync_sfx>%?\t%1, %0\";
>>>>>> else
>>>>>> - return \"stl<sync_sfx>\t%1, %0\";
>>>>>> + return \"stl<sync_sfx>%?\t%1, %0\";
>>>>>> }
>>>>>> )
>>>>>>
next prev parent reply other threads:[~2015-06-04 8:17 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-03 5:27 Shiva Chen
2015-06-03 8:31 ` Ramana Radhakrishnan
2015-06-03 8:36 ` Kyrill Tkachov
[not found] ` <556EBBAC.2020504@arm.com>
2015-06-03 8:53 ` Kyrill Tkachov
2015-06-03 9:33 ` Shiva Chen
2015-06-04 4:51 ` Shiva Chen
2015-06-04 8:24 ` Kyrill Tkachov [this message]
2015-06-04 8:42 ` Richard Earnshaw
2015-06-04 10:01 ` Shiva Chen
2015-06-04 10:04 ` Kyrill Tkachov
2015-06-05 8:34 ` Shiva Chen
2015-06-05 8:35 ` Kyrill Tkachov
2015-06-05 10:59 ` Shiva Chen
2015-06-05 13:11 ` Kyrill Tkachov
2015-06-05 13:14 ` Richard Earnshaw
2015-06-05 14:02 ` Kyrill Tkachov
2015-06-09 8:44 ` Kyrill Tkachov
2015-09-30 17:10 ` Kyrill Tkachov
2015-10-01 9:10 ` Kyrill Tkachov
2015-10-01 20:21 ` Christophe Lyon
2015-10-02 12:57 ` Kyrill Tkachov
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