From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 19 Mar 2009 18:10:17 +0000 (-0700)
Subject: Add '-fwrapv' to gcc CFLAGS
X-Git-Tag: v2.6.29~20
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=68df3755e383e6fecf2354a67b08f92f18536594;p=pandora-kernel.git

Add '-fwrapv' to gcc CFLAGS

This makes sure that gcc doesn't try to optimize away wrapping
arithmetic, which the kernel occasionally uses for overflow testing, ie
things like

	if (ptr + offset < ptr)

which technically is undefined for non-unsigned types. See

	http://bugzilla.kernel.org/show_bug.cgi?id=12597

for details.

Not all versions of gcc support it, so we need to make it conditional
(it looks like it was introduced in gcc-3.4).

Reminded-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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