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An unexpected perf feature
LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
PostgreSQL 9.3 beta: Federated databases and more
LWN.net Weekly Edition for May 9, 2013
Firefox 18 is now available
Posted Jan 10, 2013 10:14 UTC (Thu) by khim (subscriber, #9252)
"newer feature" is overstatement. Most likely this is the result of the old tempest: when GLibC developers changed memcpy to copy things from the end (it's faster on some CPUs for some obscure reasons) they found out that it broke few programs (Flash is the most important one).
Programs are incorrect (since memcpy was never promised to be usable with overlapping src and dst), but they are popular and that's why GLibC 2.14 has two versions of memcpy: memcpy@GLIBC2.2 and memcpy@GLIBC2.14. This basically means that more-or-less any program compiled with GLibC 2.14 is not usable with older versions of GLibC. Note that this difference only exist in x86-64 version of GLibC, 32-bit version does not have new optimized memcpy!
Posted Jan 10, 2013 19:42 UTC (Thu) by mirabilos (subscriber, #84359)
https://bugzilla.mozilla.org/show_bug.cgi?id=723487 is the bugreport.
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