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Re: Devirtualization in gcc
- From: Maxim Kuvyrkov <maxim at codesourcery dot com>
- To: Ian Lance Taylor <iant at google dot com>
- Cc: Black Bit <blackbit at live dot com>, <gcc at gcc dot gnu dot org>
- Date: Tue, 1 Feb 2011 17:19:43 +0300
- Subject: Re: Devirtualization in gcc
- References: <BAY136-W2A4B871C062D22BD6B3D5BBFC0@phx.gbl> <mcrvd1czeyg.fsf@google.com>
On Jan 26, 2011, at 3:27 AM, Ian Lance Taylor wrote:
> Black Bit <blackbit@live.com> writes:
>
>> Could someone tell me if the work described in this paper http://www.linuxsymposium.org/archives/GCC/Reprints-2006/namolaru-reprint.pdf was completed and is part of gcc?Thanks
>
> To the best of my knowledge the work has not yet become part of mainline
> gcc. Perhaps the Haifa folks can correct me if I am wrong.
The approach described in the paper resembles devirtualization optimizations Martin Jambor implemented as part of the IPA CP pass. AFAIK, the two implementations were different efforts.
The implementation in current mainline does not define the lattice to track types as clear as the paper, but functionally it is very similar. We (CodeSourcery) have patches that refactor type propagation code in ipa-cp.c to clearly describe the type information lattice [*]. Having information represented as lattice is advantageous as it makes it easier to reuse devirtualization analysis in other optimization passes.
[*] http://gcc.gnu.org/ml/gcc/2010-12/msg00461.html
--
Maxim Kuvyrkov
CodeSourcery
+7-812-677-6839