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Re: Preventing link time optimization from inlining


On Fri, Dec 21, 2012 at 4:41 AM, Richard Biener
<richard.guenther@gmail.com> wrote:
>
> On Thu, Dec 20, 2012 at 5:33 PM, Adam <adam.j.lewis@gmail.com> wrote:
> > Hi,
> >
> > When using -flto is there a way to tell gcc to not inline a particular function? attribute noinline appears to have no effect. I am using gcc 4.7.2. The use case is for certain functions that cause optimization problems when they are inlined. An example is when the function is throwing a c++ exception.
>
> attribute noinline should have the desired effect (you may need
> noclone as well).
>


Richard,

Doesn't seem to work for me. Here is what I am trying:
func.hpp ( I have tried this with various combinations and orderings
of noinline, noclone ):

void  my__func() __attribute__((noinline)) __attribute__ ((noclone));

func.cpp:
#include <cstdio>
void my__func() { printf("prnting"); }

main.cpp
#include "func.hpp"
int main() { my__func(); return 0; }


then:
g++ -O3 -g -flto main.cpp func.cpp -o lto_inline_test

I load up gdb, break main, run. disassemble and see that it is
directly calling printf instead of my__func.

gcc -v:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.7.2-11precise2'
--with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs
--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.7 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--enable-gnu-unique-object --enable-plugin --enable-objc-gc
--disable-werror --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64 --with-tune=generic
--enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.7.2 (Ubuntu/Linaro 4.7.2-11precise2)

Any thoughts?




> Richard.
>
> > Thanks,
> > Adam


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