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| author | Zdenek Dvorak <dvorakz@suse.cz> | 2005-07-20 10:29:44 +0200 |
|---|---|---|
| committer | Zdenek Dvorak <rakdver@gcc.gnu.org> | 2005-07-20 08:29:44 +0000 |
| commit | 67135ef48c6a53e06305d1038c4855e887568989 (patch) | |
| tree | ecb3c95d660caafb5ccf9f5afd401731fe245609 | |
| parent | fdda361d74d0d7a3a1f3abba358139846e6a05c8 (diff) | |
| download | gcc-67135ef48c6a53e06305d1038c4855e887568989.zip gcc-67135ef48c6a53e06305d1038c4855e887568989.tar.gz gcc-67135ef48c6a53e06305d1038c4855e887568989.tar.bz2 | |
* doc/trouble.texi: Update section on handling of empty loops.
From-SVN: r102190
| -rw-r--r-- | gcc/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/doc/trouble.texi | 8 |
2 files changed, 6 insertions, 6 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 61dbaef..fd08ae3 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,7 @@ +2005-07-20 Zdenek Dvorak <dvorakz@suse.cz> + + * doc/trouble.texi: Update section on handling of empty loops. + 2005-07-20 Kazu Hirata <kazu@codesourcery.com> * config.gcc: Remove support for sparc-*-openbsd*, diff --git a/gcc/doc/trouble.texi b/gcc/doc/trouble.texi index 01c0c19..c65ad70 100644 --- a/gcc/doc/trouble.texi +++ b/gcc/doc/trouble.texi @@ -1220,14 +1220,10 @@ However, the rationale here is that optimization of a nonempty loop cannot produce an empty one. This held for carefully written C compiled with less powerful optimizers but is not always the case for carefully written C++ or with more powerful optimizers. - -@opindex funroll-loops Thus GCC will remove operations from loops whenever it can determine those operations are not externally visible (apart from the time taken -to execute them, of course). As GCC improves, it will remove the loop -itself. Indeed, with @option{-funroll-loops} small loops can already be -removed, so leaving an empty non-unrolled loop is both sub-optimal and -inconsistent. +to execute them, of course). In case the loop can be proved to be finite, +GCC will also remove the loop itself. Be aware of this when performing timing tests, for instance the following loop can be completely removed, provided |