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Diffstat (limited to 'gcc/doc/invoke.texi')
| -rw-r--r-- | gcc/doc/invoke.texi | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 001ab25..1190c97 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -278,6 +278,7 @@ in the following sections. -fomit-frame-pointer -foptimize-register-move @gol -foptimize-sibling-calls -fprefetch-loop-arrays @gol -freduce-all-givs -fregmove -frename-registers @gol +-freorder-blocks -freorder-functions @gol -frerun-cse-after-loop -frerun-loop-opt @gol -fschedule-insns -fschedule-insns2 @gol -fsingle-precision-constant -fssa -fssa-ccp -fssa-dce @gol @@ -3712,6 +3713,23 @@ non-determinism is of paramount import. This switch allows users to reduce non-determinism, possibly at the expense of inferior optimization. +@item -freorder-blocks +@opindex freorder-blocks +Reorder basic blocks in the compiled function in order to reduce number of +taken branches and improve code locality. + +@item -freorder-functions +@opindex freorder-functions +Reorder basic blocks in the compiled function in order to reduce number of +taken branches and improve code locality. This is implemented by using special +subsections @code{text.hot} for most frequently executed functions and +@code{text.unlikely} for unlikely executed functions. Reordering is done by +the linker so object file format must support named sections and linker must +place them in resonable way. + +Also profile feedback must be available in to make this option effective. See +@option{-fprofile-arcs} for details. + @item -fstrict-aliasing @opindex fstrict-aliasing Allows the compiler to assume the strictest aliasing rules applicable to @@ -3900,6 +3918,13 @@ The maximum number of instructions that a loop should have if that loop is unrolled, and if the loop is unrolled, it determines how many times the loop code is unrolled. +@item hot-bb-count-fraction +Select fraction of the maximal count of repetitions of basic block in program +given basic block needs to have to be considered hot. + +@item hot-bb-frequency-fraction +Select fraction of the maximal frequency of executions of basic block in +function given basic block needs to have to be considered hot @end table @end table @@ -7389,6 +7414,10 @@ boundary. Aligning @code{double} variables on a two word boundary will produce code that runs somewhat faster on a @samp{Pentium} at the expense of more memory. +@strong{Warning:} if you use the @samp{-malign-double} switch, +structures containing the above types will be aligned differently than +the published application binary interface specifications for the 386. + @item -m128bit-long-double @opindex m128bit-long-double Control the size of @code{long double} type. i386 application binary interface |