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Ship it!


i don't think this is really a problem, but you mention it could work with 
debug and don't include the lto flags in the debug binary. 

- Ali Saidi


On May 2, 2012, 11:25 a.m., Andreas Hansson wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> http://reviews.gem5.org/r/1171/
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> 
> (Updated May 2, 2012, 11:25 a.m.)
> 
> 
> Review request for Default.
> 
> 
> Description
> -------
> 
> gcc: Enable Link-Time Optimization for gcc >= 4.6
> 
> This patch adds a scons flag to indicate that compilation and linking
> should be done using LTO. No check is used to guarantee that the
> linked supports LTO, so the user has to ensure that binutils GNU ld >=
> 2.21 or the gold linker is available.
> 
> The same number of jobs is used for the parallel phase of LTO as the
> jobs specified on the scons command line, using the -flto=n flag that
> was introduced with gcc 4.6.
> 
> Currently the LTO option is only useful for gcc >= 4.6, due to the
> limited support on clang and earlier versions of gcc. The intention is
> to also add support for clang once the LTO integration matures. The
> use of LTO is independent of the target, i.e. debug, opt, fast and
> pro, although opt and fast are the most likely candidates.
> 
> The compilation and linking (wall) time is increased by almost 50% for
> the observed cases, and simulation performance improves by roughly
> 15%, i.e. for long regression runs it really helps.
> 
> 
> Diffs
> -----
> 
>   SConstruct 7f36d4436074 
>   src/SConscript 7f36d4436074 
> 
> Diff: http://reviews.gem5.org/r/1171/diff/
> 
> 
> Testing
> -------
> 
> util/regress all passing (disregarding t1000 and eio)
> 
> 
> Thanks,
> 
> Andreas Hansson
> 
>

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