Preventing gcc from aligning stack???

[Jamie Lokier]

Tuukka Toivonen wrote:
> > Yes it is. New gcc's (try to) keep the stack aligned at 16 bytes. The
> > kernel stack is 8Kb on ia32; the 16byte alignment is mostly for floating
> > point performance on Pentium and up, and floating point is forbidden in the
> 
> I'd like to ask, why? Even double is only 8 bytes. Does this mean that 12
> bytes is wasted each argumentless call and -fno-omit-frame-pointer, for
> saving ebp?

Yes.  And gcc does tend to emit redundant stack alignment instructions
too (though this is being improved).

So turning off stack alignment reduces stack usage _and_ reduces the
code size.

-- Jamie

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