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

63 lines
1.9 KiB
Factor

! Copyright (C) 2008, 2009 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: kernel accessors sequences combinators combinators.short-circuit
classes vectors compiler.cfg compiler.cfg.instructions compiler.cfg.rpo ;
IN: compiler.cfg.useless-blocks
: update-predecessor-for-delete ( bb -- )
! We have to replace occurrences of bb with bb's successor
! in bb's predecessor's list of successors.
dup predecessors>> first [
[
2dup eq? [ drop successors>> first ] [ nip ] if
] with map
] change-successors drop ;
: update-successor-for-delete ( bb -- )
! We have to replace occurrences of bb with bb's predecessor
! in bb's sucessor's list of predecessors.
dup successors>> first [
[
2dup eq? [ drop predecessors>> first ] [ nip ] if
] with map
] change-predecessors drop ;
: delete-basic-block ( bb -- )
[ update-predecessor-for-delete ]
[ update-successor-for-delete ]
bi ;
: delete-basic-block? ( bb -- ? )
{
[ instructions>> length 1 = ]
[ predecessors>> length 1 = ]
[ successors>> length 1 = ]
[ instructions>> first ##branch? ]
} 1&& ;
: delete-useless-blocks ( cfg -- cfg' )
dup [
dup delete-basic-block? [ delete-basic-block ] [ drop ] if
] each-basic-block
f >>post-order ;
: delete-conditional? ( bb -- ? )
dup instructions>> [ drop f ] [
peek class {
##compare-branch
##compare-imm-branch
##compare-float-branch
} memq? [ successors>> first2 eq? ] [ drop f ] if
] if-empty ;
: delete-conditional ( bb -- )
dup successors>> first 1vector >>successors
[ but-last \ ##branch new-insn suffix ] change-instructions
drop ;
: delete-useless-conditionals ( cfg -- cfg' )
dup [
dup delete-conditional? [ delete-conditional ] [ drop ] if
] each-basic-block
f >>post-order ;