Re: [google][4.7] Allow function reordering linker plugin to separate hot and cold code into different ELF segments

[Sriraman Tallam <tmsriram at google dot com>]

On Fri, Jan 4, 2013 at 2:32 PM, Xinliang David Li <davidxl@google.com> wrote:
> Looks good -- but better with followup :
> 1) give a warning when the parameter to the option is not allowed;
> 2) add test cases if possible.

Made all the changes. Modified the test case to check if the segment
splitting API is invoked. The gold linker has a test case to check if
the segment API actually splits segments.

Thanks,
-Sri.

>
> David
>
>
> On Fri, Jan 4, 2013 at 2:19 PM, Sriraman Tallam <tmsriram@google.com> wrote:
>> Attached new patch.
>>
>> Thanks,
>> -Sri.
>>
>> On Fri, Jan 4, 2013 at 9:12 AM, Rong Xu <xur@google.com> wrote:
>>> The code looks fine to me. Please consider David's comments about the
>>> option name.
>>>
>>> -Rong
>>>
>>> On Thu, Jan 3, 2013 at 9:14 PM, Xinliang David Li <davidxl@google.com> wrote:
>>>> Is it better to change the option to something like:
>>>>
>>>> split_segment|nosplit-segment
>>>> or split_segment=yes|no
>>>>
>>>>
>>>> David
>>>>
>>>> On Thu, Jan 3, 2013 at 5:41 PM, Sriraman Tallam <tmsriram@google.com> wrote:
>>>>> Hi Rong,
>>>>>
>>>>>   The following patch modifies the behaviour of the linker plugin to
>>>>> not create a separate segment for cold sections by default. Separate
>>>>> segments can be created with the plugin option "segment=cold". Is this
>>>>> alright to commit?
>>>>>
>>>>> Thanks,
>>>>> -Sri.
>>>>>
>>>>> On Mon, Dec 17, 2012 at 11:14 AM, Sriraman Tallam <tmsriram@google.com> wrote:
>>>>>> I have committed this patch.
>>>>>>
>>>>>> Thanks,
>>>>>> -Sri.
>>>>>>
>>>>>> On Fri, Dec 14, 2012 at 4:16 PM, Rong Xu <xur@google.com> wrote:
>>>>>>> Looks good to me for google/gcc-4_7 branch.
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> -Rong
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Dec 14, 2012 at 3:42 PM, Sriraman Tallam <tmsriram@google.com>
>>>>>>> wrote:
>>>>>>>>
>>>>>>>> Hi Rong,
>>>>>>>>
>>>>>>>>     Please review this code. This code allows the function reordering
>>>>>>>> plugin to separate hot and cold code into different ELF segments.
>>>>>>>> This would allow optimizations like mapping the hot code alone to huge
>>>>>>>> pages.
>>>>>>>>
>>>>>>>>     With this patch, by default, the plugin maps .text.unlikely
>>>>>>>> sections into a separate ELF segment.  This can be turned off with
>>>>>>>> plugin option "--segment=none".
>>>>>>>>
>>>>>>>>     The include/plugin-api.h changes are a backport from trunk.
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> -Sri.
>>>>>>>
>>>>>>>

Attachment: reordering_plugin_patch.txt
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