Hi,
On Mon, May 20, 2013 at 09:40:52AM -0300, Adhemerval Zanella wrote:
> Hi,
>
> Thanks for reporting it, I saw it too when building glibc with gcc-trunk.
> Carlos O'Donell already reported it could be an issue to glibc at
> http://sourceware.org/ml/libc-alpha/2013-02/msg00299.html and I also noted
> it causes PTL issues too at
> http://sourceware.org/ml/libc-alpha/2013-04/msg00124.html
> I have proposed a patch
> http://sourceware.org/ml/libc-alpha/2013-04/msg00196.html
> so configure can check if compiler transform loops into libc functions calls,
> but
> Andreas Jaeger and Roland McGrath didn't approve the approach.
>
> Although, the problem persist and I think we need to figure out how to
> proceed
> before 2.18 release. Based on the loader memset recursion call you observe I
> do
> suggest to use my approach and add '-fno-tree-loop-distribute-patterns' on
> rtld-memset.os object.
>
> Any comments?
tree-loop-distribute-patterns is enabled on gcc-4.7.3 with -O3:
# /usr/gcc47/bin/gcc --version
gcc (GCC) 4.7.3
[....]
# /usr/gcc47/bin/gcc -c -Q -O3 --help=optimizers | fgrep
tree-loop-distribute-patterns
-ftree-loop-distribute-patterns [enabled]
And it looks like it's the default for a long time:
# fgrep OPT_ftree_loop_distribute_patterns gcc-*/gcc/opts.c
gcc-4.6.3/gcc/opts.c: { OPT_LEVELS_3_PLUS,
OPT_ftree_loop_distribute_patterns, NULL, 1 },
gcc-4.7.0/gcc/opts.c: { OPT_LEVELS_3_PLUS,
OPT_ftree_loop_distribute_patterns, NULL, 1 },
gcc-4.7.1/gcc/opts.c: { OPT_LEVELS_3_PLUS,
OPT_ftree_loop_distribute_patterns, NULL, 1 },
gcc-4.7.2/gcc/opts.c: { OPT_LEVELS_3_PLUS,
OPT_ftree_loop_distribute_patterns, NULL, 1 },
gcc-4.7.3/gcc/opts.c: { OPT_LEVELS_3_PLUS,
OPT_ftree_loop_distribute_patterns, NULL, 1 },
gcc-4.8.0/gcc/opts.c: { OPT_LEVELS_3_PLUS,
OPT_ftree_loop_distribute_patterns, NULL, 1 },
I wonder what's the difference between gcc-4.7.3 and gcc-4.8.x for
'tree-loop-distribute-patterns' ........
regards
winfried
