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This is an automatically generated e-mail. To reply, visit:
http://reviews.gem5.org/r/1282/
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Review request for Default.


Description
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Changeset 9087:afe51ef2ba41
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gcc: Enable tuning for native CPU features for gcc >= 4.2

This patch adds a scons flag to indicate that compilation should be
done using gcc's automatic identification of CPU features. This flag
is expanded based on the CPUID, for example on my Core i3 CPU,
"-march=native" turns into "-march=core2 -mcx16 -msahf -mpopcnt
-msse4.2 --param l1-cache-size=32 --param l1-cache-line-size=64
--param l2-cache-size=256 -mtune=core2", thus tuning both for the
cache organisation, and potentially using instructions which are
specific to the CPU.

If you compile and execute on different machines this may obviously
cause problems, so beware. The flag is also known to cause problems
with distcc (as you can imagine). When compiling for local execution,
this flag should be the default option, and we might want to invert it
at some point to say --no-native and be default on.

Performance benchmarks are in progress and I will bump the patch once
some numbers are available.


Diffs
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  SConstruct ace8383f2b7e 

Diff: http://reviews.gem5.org/r/1282/diff/


Testing
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Compiled correctly using a variety of gcc versions. Performance testing in 
progress.


Thanks,

Andreas Hansson

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