diff options
Diffstat (limited to 'gcc/doc/invoke.texi')
| -rw-r--r-- | gcc/doc/invoke.texi | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 9df741439f4..e166964c28d 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -407,7 +407,7 @@ Objective-C and Objective-C++ Dialects}. -ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @gol -ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol -ftree-parallelize-loops=@var{n} -ftree-pre -ftree-pta -ftree-reassoc @gol --ftree-sink -ftree-sra -ftree-switch-conversion @gol +-ftree-sink -ftree-sra -ftree-switch-conversion -ftree-tail-merge @gol -ftree-ter -ftree-vect-loop-version -ftree-vectorize -ftree-vrp @gol -funit-at-a-time -funroll-all-loops -funroll-loops @gol -funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops @gol @@ -6137,7 +6137,7 @@ also turns on the following optimization flags: -fsched-interblock -fsched-spec @gol -fschedule-insns -fschedule-insns2 @gol -fstrict-aliasing -fstrict-overflow @gol --ftree-switch-conversion @gol +-ftree-switch-conversion -ftree-tail-merge @gol -ftree-pre @gol -ftree-vrp} @@ -7020,6 +7020,13 @@ Perform conversion of simple initializations in a switch to initializations from a scalar array. This flag is enabled by default at @option{-O2} and higher. +@item -ftree-tail-merge +Look for identical code sequences. When found, replace one with a jump to the +other. This optimization is known as tail merging or cross jumping. This flag +is enabled by default at @option{-O2} and higher. The run time of this pass can +be limited using @option{max-tail-merge-comparisons} parameter and +@option{max-tail-merge-iterations} parameter. + @item -ftree-dce @opindex ftree-dce Perform dead code elimination (DCE) on trees. This flag is enabled by @@ -8603,6 +8610,14 @@ This is used to avoid quadratic behavior in hoisting algorithm. The value of 0 will avoid limiting the search, but may slow down compilation of huge functions. The default value is 30. +@item max-tail-merge-comparisons +The maximum amount of similar bbs to compare a bb with. This is used to +avoid quadratic behaviour in tree tail merging. The default value is 10. + +@item max-tail-merge-iterations +The maximum amount of iterations of the pass over the function. This is used to +limit run time in tree tail merging. The default value is 2. + @item max-unrolled-insns 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 |