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Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA

From: Paul Eggert
Subject: Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA
Date: Sun, 19 Jun 2011 23:50:24 -0700
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20110516 Thunderbird/3.1.10

On 06/19/11 23:35, Ralf Wildenhues wrote:
> If you don't use volatile, the compiler is pretty much free to give you
> whatever answer it likes today.

It's true that the test relies on undefined behavior, and so the
compiler is free to do whatever it wants, but I don't see how
adding "volatile" helps, for this particular test.  Whatever reasoning
the compiler can do without "volatile", it can also do with "volatile",
for this test.

(I have more confidence in the revised test, because this
time I actually ran it on an x86-64 host with GCC 4.6.0.  :-)

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