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On Wed, 21 Dec 2011, Corinna Vinschen wrote: > On second thought I'm a bit puzzled that the pthread stack isn't > correctly aligned as well. Ignoring the pthread_attr_setstack case > which wasn't supported so far anyway, the OS stack set up by > CreateThread is 64K aligned. From that 64K aligned StackBase value, I > subtract 12704 == 0x31a0 bytes. So the result should be 16 byte > aligned even without the andl $-16, %%esp. Why isn't it?!? It appears it is, here. > Does anybody care to tell me what's wrong with the assembler code in > thread_wrapper? I don't pretend to understand why, but it appears gcc is expecting the stack to be 16 byte aligned on entry to the called function, which includes the 4 byte argument and the 4 byte return address in this case. I could be wrong, but it appears that would do it. For a long discussion by those who apparently agree with you about how crazy this is see: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838 It looks like gcc 4.6 may finally "do the right thing" itself. -- Brian Ford Staff Realtime Software Engineer VITAL - Visual Simulation Systems FlightSafety International the best safety device in any aircraft is a well-trained crew... -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
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