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| author | Tobias Burnus <burnus@net-b.de> | 2014-03-08 23:13:26 +0100 |
|---|---|---|
| committer | Tobias Burnus <burnus@gcc.gnu.org> | 2014-03-08 23:13:26 +0100 |
| commit | 433d6b398610cadfd7ee1e73165b72b3a6c5009d (patch) | |
| tree | 10fe31ee5216308d32afd19e85f37d8b50a71391 /libgfortran | |
| parent | 21d89690699adb7f9737b1bf17d076e21967dd72 (diff) | |
| download | gcc-433d6b398610cadfd7ee1e73165b72b3a6c5009d.zip gcc-433d6b398610cadfd7ee1e73165b72b3a6c5009d.tar.gz gcc-433d6b398610cadfd7ee1e73165b72b3a6c5009d.tar.bz2 | |
libgfortran.h (unlikely, likely): Add usage comment.
2014-03-08 Tobias Burnus <burnus@net-b.de>
* libgfortran.h (unlikely, likely): Add usage comment.
From-SVN: r208434
Diffstat (limited to 'libgfortran')
| -rw-r--r-- | libgfortran/ChangeLog | 4 | ||||
| -rw-r--r-- | libgfortran/libgfortran.h | 10 |
2 files changed, 14 insertions, 0 deletions
diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog index 4005df0..c82daa2 100644 --- a/libgfortran/ChangeLog +++ b/libgfortran/ChangeLog @@ -1,3 +1,7 @@ +2014-03-08 Tobias Burnus <burnus@net-b.de> + + * libgfortran.h (unlikely, likely): Add usage comment. + 2014-03-08 Dominique d'Humieres <dominiq@lps.ens.fr> PR libgfortran/60128 diff --git a/libgfortran/libgfortran.h b/libgfortran/libgfortran.h index d7e15ad..0d6f432 100644 --- a/libgfortran/libgfortran.h +++ b/libgfortran/libgfortran.h @@ -97,6 +97,16 @@ typedef off_t gfc_offset; #define NULL (void *) 0 #endif + +/* The following macros can be used to annotate conditions which are likely or + unlikely to be true. Avoid using them when a condition is only slightly + more likely/less unlikely than average to avoid the performance penalties of + branch misprediction. In addition, as __builtin_expect overrides the compiler + heuristic, do not use in conditions where one of the branches ends with a + call to a function with __attribute__((noreturn)): the compiler internal + heuristic will mark this branch as much less likely as unlikely() would + do. */ + #ifndef __GNUC__ #define __attribute__(x) #define likely(x) (x) |