Re: [RFC] libstdc++ atomicity, x86 agnostic version

[Paolo Carlini <pcarlini at suse dot de>]

Benjamin Kosnik wrote:

> Using Jakub's test:
>
> #include <string>
>
> using namespace std;
>
> bool b = true;
> const string s = "abc";
>
> void foo(string &x)
> { }
>
> int main (void)
> {
>  for (int i = 0; i < 10000000; ++i)
>    {
>      string t = s;
>      foo(t);
>    }
> }
>  
Well, it looks like part of the test is bogus (sorry Jakub!) since the 
argument x of foo is a reference and therefore no constructions and 
destructions take place...

> I get:
>
> %time ./gcc-3.4-atomic.exe
> 1.740u 0.000s 0:01.79 97.2%     0+0k 0+0io 166pf+0w
> 1.750u 0.000s 0:01.76 99.4%     0+0k 0+0io 166pf+0w
> <bkoz@roscoe> /home/bkoz/string_tests 
> %time ./gcc-3.4.exe
> 1.560u 0.010s 0:01.59 98.7%     0+0k 0+0io 165pf+0w
> 1.580u 0.000s 0:01.59 99.3%     0+0k 0+0io 165pf+0w
> <bkoz@roscoe> /home/bkoz/string_tests 
> %time ./gcc-3.3.2.exe
> 1.660u 0.000s 0:01.67 99.4%     0+0k 0+0io 203pf+0w
> 1.650u 0.000s 0:01.66 99.3%     0+0k 0+0io 203pf+0w
>  
I see. Seems something reasonable for 3.4...

However, I would really like to carry out some tests myself (also in the 
light of the observation above): unfortunately, after having applied 
your patch and regenerated everything (aclocal - autoconf - autoheader - 
automake from the top libstdc++-v3 dir) I'm getting:

make[3]: Leaving directory 
`/home/paolo/Gcc/cvs-dirs/gcc-head-build/i686-pc-linux-gnu/libstdc++-v3'
Making all in include
make[3]: Entering directory 
`/home/paolo/Gcc/cvs-dirs/gcc-head-build/i686-pc-linux-gnu/libstdc++-v3/include'
make[3]: *** No rule to make target 
`/home/paolo/Gcc/cvs-dirs/gcc-head/gcc/libstdc++-v3/include/bits/atomicity.h', 
needed by `stamp-bits'.
Stop.
make[3]: Leaving directory 
`/home/paolo/Gcc/cvs-dirs/gcc-head-build/i686-pc-linux-gnu/libstdc++-v3/include'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory 
`/home/paolo/Gcc/cvs-dirs/gcc-head-build/i686-pc-linux-gnu/libstdc++-v3'
make[1]: *** [all] Error 2
make[1]: Leaving directory 
`/home/paolo/Gcc/cvs-dirs/gcc-head-build/i686-pc-linux-gnu/libstdc++-v3'
make: *** [all-target-libstdc++-v3] Error 2

What I'm doing wrong?

Thanks,
Paolo.