diff options
Diffstat (limited to 'gcc/doc/invoke.texi')
| -rw-r--r-- | gcc/doc/invoke.texi | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 567dc5caf92..3b258fe2456 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -315,7 +315,7 @@ Objective-C and Objective-C++ Dialects}. -fsignaling-nans -fsingle-precision-constant -fspeculative-prefetching @gol -fstrength-reduce -fstrict-aliasing -ftracer -fthread-jumps @gol -funroll-all-loops -funroll-loops -fpeel-loops @gol --funswitch-loops @gol +-fsplit-ivs-in-unroller -funswitch-loops @gol -ftree-pre -ftree-ccp -ftree-dce -ftree-loop-optimize @gol -ftree-loop-linear -ftree-loop-im -ftree-loop-ivcanon -fivopts @gol -ftree-dominator-opts -ftree-dse -ftree-copyrename @gol @@ -4696,6 +4696,20 @@ the loop is entered. This usually makes programs run more slowly. @option{-funroll-all-loops} implies the same options as @option{-funroll-loops}, +@item -fsplit-ivs-in-unroller +@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). + +Combination of @option{-fweb} and CSE is often sufficient to obtain the +same effect. However in cases the loop body is more complicated than +a single basic block, this is not reliable. It also does not work at all +on some of the architectures due to restrictions in the CSE pass. + +This optimization is enabled by default. + @item -fprefetch-loop-arrays @opindex fprefetch-loop-arrays If supported by the target machine, generate instructions to prefetch |
