[Python-Dev] HEADS UP: Compilation risk with new GCC 4.5.0 (original) (raw)

Jesus Cea jcea at jcea.es
Wed May 12 16:01:19 CEST 2010

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On 12/05/10 15:39, James Y Knight wrote:

While assuming the stack is 16byte aligned is undeniably an ABI-violation in GCC, at this point, it's surely simpler to just go along: the new unofficial ABI for x86 is that the stack must always be left in 16-byte alignment...

You can not rule out other software embedding python inside, or callbacks from foreign code. For instance, Berkeley DB library can do callbacks to Python code.

So, just change psyco to always use 16-byte-aligned stackframes. GCC has used 16byte-aligned stackframes for a heck of a long time now (so if the stack starts 16byte aligned on entry to a function it will stay that way on calls). So usually the only way people run into unaligned stacks is via hand-written assembly code or JIT compilers.

Not all the universe is GCC based. For instance, Solaris system libraries are not compiled using GCC. The world is bigger that Linux/GCC.

I think you'll be a lot happier just modifying Psyco than making everyone else in the world change their compiler flags.

Would be nice if GCC 4.5.1 would solve this :). They are objectivelly breaking the x86 ABI.

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