[Python-Dev] A new JIT compiler for a faster CPython? (original) (raw)

Ned Deily nad at acm.org
Wed Jul 18 10:55:13 CEST 2012

In article <20120718075314.Horde.ty5wC7uWis5QBk9Krz1hyUA at webmail.df.eu>, martin at v.loewis.de wrote:

I don't think it is. It is still slow and memory hungry. The fact that the version that Apple ships with Xcode still miscompiles Python 3.3 tells me that it is still buggy.

Whether LLVM is suitable for a JIT is an interesting question but it's not LLVM per se that is the problem with compiling 3.3. Apple ships two C compiler chains with Xcode 4 for OS X 10.7, both of them are based on LLVM. It's the Apple transitional gcc-4.2 frontend with an old LLVM backend that is problematic (and not to be confused with the "pure" gcc-4.2 shipped with Xcode 3). That compiler was the default compiler for early releases of Xcode 4 and for building OS X 10.7. It has been frozen for a long time because Apple's efforts have been going into transitioning the OS X world to the new compiler: a clang frontend with a more current LLVM backend. The latest releases of Xcode 4 now use clang-llvm as the default and that's what we now use as a default for building Python 3.3 with Xcode 4. That transition will be complete with the imminent release of OS X 10.8 Mountain Lion when the whole OS is built with clang-llvm. The iOS world is already there.

-- Ned Deily, nad at acm.org

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