basis/compiler/cfg/useless-conditionals/useless-conditionals.factor

   1 ! Copyright (C) 2008, 2010 Slava Pestov.
   2 ! See https://factorcode.org/license.txt for BSD license.
   3 USING: accessors combinators.short-circuit compiler.cfg
   4 compiler.cfg.instructions compiler.cfg.rpo
   5 compiler.cfg.utilities kernel sequences vectors ;
   6 IN: compiler.cfg.useless-conditionals
   7
   8 : delete-conditional? ( bb -- ? )
   9     {
  10         [
  11             instructions>> last {
  12                 [ ##compare-branch? ]
  13                 [ ##compare-imm-branch? ]
  14                 [ ##compare-integer-branch? ]
  15                 [ ##compare-integer-imm-branch? ]
  16                 [ ##compare-float-ordered-branch? ]
  17                 [ ##compare-float-unordered-branch? ]
  18             } 1||
  19         ]
  20         [ successors>> first2 [ skip-empty-blocks ] bi@ eq? ]
  21     } 1&& ;
  22
  23 : delete-conditional ( bb -- )
  24     [ first skip-empty-blocks 1vector ] change-successors
  25     instructions>> [ pop* ] [ [ ##branch new-insn ] dip push ] bi ;
  26
  27 : delete-useless-conditionals ( cfg -- )
  28     [
  29         [
  30             dup delete-conditional? [ delete-conditional ] [ drop ] if
  31         ] each-basic-block
  32     ]
  33     [ cfg-changed ] [ predecessors-changed ] tri ;