[Bug target/56165] Missed optimization for 'noreturn' functions

akobets at mail dot ru gcc-bugzilla@gcc.gnu.org
Sun Feb 3 13:48:00 GMT 2013


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56165

--- Comment #13 from Alexander Kobets <akobets at mail dot ru> 2013-02-03 13:48:15 UTC ---
(In reply to comment #12)
> That is completely irrelevant.  The noreturn function is usually defined in
> some other CU, so you don't know what compiler flags it will be compiled with,
> and -mpreferred-stack-boundary=4 (i.e. 16 bytes alignment) is for x86_64 the
> smallest supported alignment.

Now I tested with -mpreferred-stack-boundary=4
it has no effect.
-mpreferred-stack-boundary=4 do not worked, it is fake.

> Even if you don't use SSE etc., the compiler is
> allowed and does assume the 16-byte alignment of stack pointer in many places.

I try to use some options for explain to compolers what I want.

> Note -mcmodel=large in your flags is much bigger slowdown than what you are
> complaining about here.

I will take it in account. But I need mainly the unchanged stack pointer at
function run.



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