[gentoo-user] Re: Gcc 4.3.4 ---> 4.4.1

[Nikos Chantziaras <realnc@arcor.de>]

On 08/15/2009 08:07 PM, 7v5w7go9ub0o wrote:
> [...]
> 1. FWIW, I found the following note:
>
> "To use this code transformation, GCC has to be configured with
> --with-ppl and --with-cloog to enable the Graphite loop transformation
> infrastructure."
>
> on the following page:
>
> <http://gcc.gnu.org/onlinedocs/gcc-4.4.1/gcc/Optimize-Options.html#Optimize-Options>

On Gentoo you just need to enable the "graphite" GCC USE flag.  This 
will pull-in ">=dev-libs/ppl-0.10" and ">=dev-libs/cloog-ppl-0.15". 
Also, "gcc -v" will show: "--with-ppl --with-cloog".


> 2. Also FWIW, I found the following note:
>
> * GCC can now emit code for protecting applications from
> stack-smashing attacks. The protection is realized by buffer overflow
> detection and reordering of stack variables to avoid pointer corruption.
> * Some built-in functions have been fortified to protect them
> against various buffer overflow (and format string) vulnerabilities.
> Compared to the mudflap bounds checking feature, the safe builtins have
> far smaller overhead. This means that programs built using safe builtins
> should not experience any measurable slowdown.
>
> on the following page: <http://gcc.gnu.org/gcc-4.1/changes.html>
>
> which suggests to me that the mudflap option should be disabled before
> emerging world

AFAIK, the mudflap pointer checker is just a command line GCC switch. 
You need to enable it explicitly using "-fmudflap".