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| author | Aldy Hernandez <aldyh@gcc.gnu.org> | 2001-01-17 19:43:13 +0000 |
|---|---|---|
| committer | Aldy Hernandez <aldyh@gcc.gnu.org> | 2001-01-17 19:43:13 +0000 |
| commit | 454d0cc7dd3ebc42b52d44b0a681eb6c14f5820e (patch) | |
| tree | c1ea06892a37aaa1493ad281873854f6e1c074de /gcc | |
| parent | 5f3aebeadf5ab4252900620f88a2159b2bafca3f (diff) | |
| download | gcc-454d0cc7dd3ebc42b52d44b0a681eb6c14f5820e.zip gcc-454d0cc7dd3ebc42b52d44b0a681eb6c14f5820e.tar.gz gcc-454d0cc7dd3ebc42b52d44b0a681eb6c14f5820e.tar.bz2 | |
document -fno-guess-branch-probability option
From-SVN: r39096
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/invoke.texi | 12 |
2 files changed, 16 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 3206f2c..1d129cb 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,9 +1,14 @@ +2001-01-17 Aldy Hernandez <aldyh@redhat.com> + + * invoke.texi (-fno-guess-branch-probability): New option. + Wed Jan 17 13:26:34 2001 Richard Kenner <kenner@vlsi1.ultra.nyu.edu> * combine.c (try_combine): Don't set i3_subst_into_i2 for case of making new double-word constant. Revert last change: instead just test i3_subst_into_i2. +>>>>>>> 1.9022 2001-01-17 Jakub Jelinek <jakub@redhat.com> * config/i386/i386.md (cmpqi_minus_1): Use {b} for QImode operation. diff --git a/gcc/invoke.texi b/gcc/invoke.texi index 4536ba6..8a7a922 100644 --- a/gcc/invoke.texi +++ b/gcc/invoke.texi @@ -244,7 +244,8 @@ in the following sections. -finline-functions -finline-limit=@var{n} -fkeep-inline-functions @gol -fkeep-static-consts -fmove-all-movables @gol -fno-default-inline -fno-defer-pop @gol --fno-function-cse -fno-inline -fno-math-errno -fno-peephole @gol +-fno-function-cse -fno-guess-branch-probability +-fno-inline -fno-math-errno -fno-peephole @gol -fomit-frame-pointer -foptimize-register-move @gol -foptimize-sibling-calls -freduce-all-givs @gol -fregmove -frename-registers @gol @@ -3123,6 +3124,15 @@ branch is mostly to take, the @samp{REG_BR_PROB} values are used to exactly determine which path is taken more often. @end ifset +@item -fno-guess-branch-probability +Sometimes gcc will opt to guess branch probabilities when none are +available from either profile directed feedback (@samp{-fprofile-arcs}) +or @samp(__builtin_expect). In a hard real-time system, people don't +want different runs of the compiler to produce code that has different +behavior; minimizing non-determinism is of paramount import. This +switch allows users to reduce non-determinism, possibly at the expense +of inferior optimization. + @item -fstrict-aliasing Allows the compiler to assume the strictest aliasing rules applicable to the language being compiled. For C (and C++), this activates |