diff options
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/invoke.texi | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 0f509d0ce7b..ba355c0d046 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -5017,8 +5017,7 @@ the loop is entered. This usually makes programs run more slowly. @opindex -fsplit-ivs-in-unroller Enables expressing of values of induction variables in later iterations of the unrolled loop using the value in the first iteration. This breaks -long dependency chains, thus improving efficiency of the scheduling passes -(for best results, @option{-fweb} should be used as well). +long dependency chains, thus improving efficiency of the scheduling passes. Combination of @option{-fweb} and CSE is often sufficient to obtain the same effect. However in cases the loop body is more complicated than @@ -5260,9 +5259,7 @@ passes, such as CSE, loop optimizer and trivial dead code remover. It can, however, make debugging impossible, since variables will no longer stay in a ``home register''. -Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}, -on targets where the default format for debugging information supports -variable tracking. +Enabled by default with @option{-funroll-loops}. @item -fwhole-program @opindex fwhole-program @@ -5524,7 +5521,7 @@ debug information format adopted by the target, however, it can make debugging impossible, since variables will no longer stay in a ``home register''. -Not enabled by default at any level because it has known bugs. +Enabled by default with @option{-funroll-loops}. @item -ftracer @opindex ftracer @@ -5538,9 +5535,10 @@ Enabled with @option{-fprofile-use}. @opindex funroll-loops Unroll loops whose number of iterations can be determined at compile time or upon entry to the loop. @option{-funroll-loops} implies -@option{-frerun-cse-after-loop}. It also turns on complete loop peeling -(i.e.@: complete removal of loops with small constant number of iterations). -This option makes code larger, and may or may not make it run faster. +@option{-frerun-cse-after-loop}, @option{-fweb} and @option{-frename-registers}. +It also turns on complete loop peeling (i.e.@: complete removal of loops with +small constant number of iterations). This option makes code larger, and may +or may not make it run faster. Enabled with @option{-fprofile-use}. |