Messages in this thread | | | Date | Wed, 9 Apr 2014 13:48:57 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 00/14] perf, x86: Haswell LBR call stack support |
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On Wed, Feb 26, 2014 at 12:26:43PM -0800, Andy Lutomirski wrote: > Speed. FPO saves one register (a big deal on x86_32; not so important > on x86_64) but also saves a few cycles on function entry and exit, > which is a bigger deal for small functions.
So I though that LTO was supposed to get rid of a lot of the small function and inline them.
I've also heard that in practise this is very 'hard', and thus we're still stuck with a gazillion small functions (mostly C++ people suffer from this).
Can anybody give a concise explanation on why LTO doesn't rid us of these small functions or point to a web resource that describes the problem?
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