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Diffstat (limited to 'gcc/f/invoke.texi')
| -rw-r--r-- | gcc/f/invoke.texi | 27 |
1 files changed, 11 insertions, 16 deletions
diff --git a/gcc/f/invoke.texi b/gcc/f/invoke.texi index f07df02cc5c..58710ce0eb1 100644 --- a/gcc/f/invoke.texi +++ b/gcc/f/invoke.texi @@ -1656,26 +1656,21 @@ but possibly slower. @item -fno-rerun-loop-opt @cindex -fno-rerun-loop-opt option @cindex options, -fno-rerun-loop-opt -@emph{Version info:} -These options are not supported by -versions of @command{g77} based on @command{gcc} version 2.8. +In general, the optimizations enabled with these options will lead to +faster code being generated by GNU Fortran; hence they are enabled by default +when issuing the @command{g77} command. -Each of these might improve performance on some code. +@option{-fmove-all-movables} and @option{-freduce-all-givs} will enable +loop optimization to move all loop-invariant index computations in nested +loops over multi-rank array dummy arguments out of these loops. -Analysis of Fortran code optimization and the resulting -optimizations triggered by the above options were -contributed by Toon Moene (@email{toon@@moene.indiv.nluug.nl}). +@option{-frerun-loop-opt} will move offset calculations resulting +from the fact that Fortran arrays by default have a lower bound of 1 +out of the loops. These three options are intended to be removed someday, once -they have helped determine the efficacy of various -approaches to improving the performance of Fortran code. - -Please let us know how use of these options affects -the performance of your production code. -We're particularly interested in code that runs faster -when these options are @emph{disabled}, and in -non-Fortran code that benefits when they are -@emph{enabled} via the above @command{gcc} command-line options. +loop optimization is sufficiently advanced to perform all those +transformations without help from these options. @end table @xref{Optimize Options,,Options That Control Optimization, |