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Re: PATCH: Turn on -fomit-frame-pointer by default for 32bit Linux/x86


On 08/04/2010 05:22 PM, Andrew Haley wrote:
> On 08/04/2010 05:08 PM, H.J. Lu wrote:
>> On Wed, Aug 4, 2010 at 7:59 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>>>
>>> I went through the defualt changing discussion at a time we was introducing
>>> x86-64 port.
>>> In general, I believe -fomit-frame-pointer by default is win. x86-64
>>> defaults to this for a while and thus the pain of switching should be limited,
>>> since most of packages adopted to 64bit world.
>>>
>>> Probably the most touchy issue concerning the switch is place
>>> where you need stack unwinding fast.  This is the case of oprofile
>>> and some of garbage collector implementations.
>>
>> Can we find if oprofile works with -fomit-frame-pointer on 32bit Linux/x86.
> 
> I'll ask.

For oprofile the answer is "Oprofile has a very simple-minded
mechanism that uses the frame pointers to walk the stack. If the frame
pointers are turned off, the call graph information oprofile generates
will be pretty limited. The flat profiling will still work fine."

Andrew.


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