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Re: [PATCH] C++ thunk section names
- From: Xinliang David Li <davidxl at google dot com>
- To: Sriraman Tallam <tmsriram at google dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, Jan Hubicka <hubicka at ucw dot cz>, Teresa Johnson <tejohnson at google dot com>
- Date: Mon, 7 Jul 2014 10:56:15 -0700
- Subject: Re: [PATCH] C++ thunk section names
- Authentication-results: sourceware.org; auth=none
- References: <CAAs8HmyUpsQTfEhWpCXRtq1JU81JxFXUtW7vtoWv5XKS_cQFxw at mail dot gmail dot com> <CAAs8Hmxjv5jNdt3jKiocjWP8nfYFGJntSxZe=W0gfLmh4RTCOg at mail dot gmail dot com> <CAAs8HmxZppw=CCdwGh-WDqGAzMskATLDNC3Z+Vm=m_XZ=4-w=w at mail dot gmail dot com> <CAAs8HmyxpgZhKzKP=DDopg8bEcz-4-W95WiBQa8rXsSvr+Z3OQ at mail dot gmail dot com> <CAAs8Hmy8nO4dA+ezq2mfW=LuFDXNjZ8hJ+YRA_Hz30+KE_cY8A at mail dot gmail dot com> <CAAs8HmyRJ0ir-h219jp5wjKPNFQnY=xQgjtzwGkh2e+qkBr6dw at mail dot gmail dot com>
Sri, can you provide examples to show why putting thunks into the same
section as the target function when function reorder is on can be bad
?
Thanks,
David
On Thu, Jun 26, 2014 at 10:29 AM, Sriraman Tallam <tmsriram@google.com> wrote:
> Hi Honza,
>
> Could you review this patch when you find time?
>
> Thanks
> Sri
>
> On Tue, Jun 17, 2014 at 10:42 AM, Sriraman Tallam <tmsriram@google.com> wrote:
>> Ping.
>>
>> On Mon, Jun 9, 2014 at 3:54 PM, Sriraman Tallam <tmsriram@google.com> wrote:
>>> Ping.
>>>
>>> On Mon, May 19, 2014 at 11:25 AM, Sriraman Tallam <tmsriram@google.com> wrote:
>>>> Ping.
>>>>
>>>> On Thu, Apr 17, 2014 at 10:41 AM, Sriraman Tallam <tmsriram@google.com> wrote:
>>>>> Ping.
>>>>>
>>>>> On Wed, Feb 5, 2014 at 4:31 PM, Sriraman Tallam <tmsriram@google.com> wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I would like this patch reviewed and considered for commit when
>>>>>> Stage 1 is active again.
>>>>>>
>>>>>> Patch Description:
>>>>>>
>>>>>> A C++ thunk's section name is set to be the same as the original function's
>>>>>> section name for which the thunk was created in order to place the two
>>>>>> together. This is done in cp/method.c in function use_thunk.
>>>>>> However, with function reordering turned on, the original function's section
>>>>>> name can change to something like ".text.hot.<orginal>" or
>>>>>> ".text.unlikely.<original>" in function default_function_section in varasm.c
>>>>>> based on the node count of that function. The thunk function's section name
>>>>>> is not updated to be the same as the original here and also is not always
>>>>>> correct to do it as the original function can be hotter than the thunk.
>>>>>>
>>>>>> I have created a patch to not name the thunk function's section to be the same
>>>>>> as the original function when function reordering is enabled.
>>>>>>
>>>>>> Thanks
>>>>>> Sri