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[Bug rtl-optimization/40838] gcc shouldn't assume that the stack is aligned



------- Comment #7 from mikulas at artax dot karlin dot mff dot cuni dot cz  2009-07-23 13:49 -------
See bug #27537, quoting "GNU/Linux follows the SYSV x86 ABI which is
documented, maybe you cannot find it but it does exist. The SYSV x86 ABI says
the stack is aligned 4 byte aligned."

That bug seems to reappear.

As Agner noted, 16-byte stack alignment requirement also break compatibility
with Intel CC. I found even some part of current glibc that violates this
16-byte alignment (calling push %eax; call exit from the assembler without
aligning the stack size).

Another point: if gcc realigns the stack, why then use movdqu to store the
values on the stack? That is suboptimal.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838


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