diff options
Diffstat (limited to 'elf/dl-profile.c')
| -rw-r--r-- | elf/dl-profile.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/elf/dl-profile.c b/elf/dl-profile.c index 83e849561a..19d1865c25 100644 --- a/elf/dl-profile.c +++ b/elf/dl-profile.c @@ -19,6 +19,7 @@ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ +#include <assert.h> #include <errno.h> #include <fcntl.h> #include <inttypes.h> @@ -217,9 +218,23 @@ _dl_start_profile (struct link_map *map, const char *output_dir) kcountsize = textsize / HISTFRACTION; hashfraction = HASHFRACTION; if ((HASHFRACTION & (HASHFRACTION - 1)) == 0) - /* If HASHFRACTION is a power of two, mcount can use shifting - instead of integer division. Precompute shift amount. */ - log_hashfraction = __ffs (hashfraction * sizeof (*froms)) - 1; + { + /* If HASHFRACTION is a power of two, mcount can use shifting + instead of integer division. Precompute shift amount. + + This is a constant but the compiler cannot compile the + expression away since the __ffs implementation is not known + to the compiler. Help the compiler by precomputing the + usual cases. */ + assert (hashfraction == 2); + + if (sizeof (*froms) == 8) + log_hashfraction = 4; + else if (sizeof (*froms) == 16) + log_hashfraction = 5; + else + log_hashfraction = __ffs (hashfraction * sizeof (*froms)) - 1; + } else log_hashfraction = -1; tossize = textsize / HASHFRACTION; |