factor/basis/compiler/cfg/stack-analysis/stack-analysis.factor

296 lines
7.9 KiB
Factor

! Copyright (C) 2009 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: accessors assocs kernel namespaces math sequences fry grouping
sets make combinators compiler.cfg.copy-prop compiler.cfg.def-use
compiler.cfg.instructions compiler.cfg.registers compiler.cfg.rpo
compiler.cfg.hats compiler.cfg ;
IN: compiler.cfg.stack-analysis
! Convert stack operations to register operations
! If 'poisoned' is set, disregard height information. This is set if we don't have
! height change information for an instruction.
TUPLE: state locs>vregs actual-locs>vregs changed-locs ds-height rs-height poisoned? ;
: <state> ( -- state )
state new
H{ } clone >>locs>vregs
H{ } clone >>actual-locs>vregs
H{ } clone >>changed-locs
0 >>ds-height
0 >>rs-height ;
M: state clone
call-next-method
[ clone ] change-locs>vregs
[ clone ] change-actual-locs>vregs
[ clone ] change-changed-locs ;
: loc>vreg ( loc -- vreg ) state get locs>vregs>> at ;
: record-peek ( dst loc -- )
state get [ locs>vregs>> set-at ] [ actual-locs>vregs>> set-at ] 3bi ;
: changed-loc ( loc -- )
state get changed-locs>> conjoin ;
: record-replace ( src loc -- )
dup changed-loc state get locs>vregs>> set-at ;
GENERIC: height-for ( loc -- n )
M: ds-loc height-for drop state get ds-height>> ;
M: rs-loc height-for drop state get rs-height>> ;
: (translate-loc) ( loc -- n height ) [ n>> ] [ height-for ] bi ; inline
GENERIC: translate-loc ( loc -- loc' )
M: ds-loc translate-loc (translate-loc) - <ds-loc> ;
M: rs-loc translate-loc (translate-loc) - <rs-loc> ;
GENERIC: untranslate-loc ( loc -- loc' )
M: ds-loc untranslate-loc (translate-loc) + <ds-loc> ;
M: rs-loc untranslate-loc (translate-loc) + <rs-loc> ;
: redundant-replace? ( vreg loc -- ? )
dup untranslate-loc n>> 0 <
[ 2drop t ] [ state get actual-locs>vregs>> at = ] if ;
: save-changed-locs ( state -- )
[ changed-locs>> ] [ locs>vregs>> ] bi '[
_ at swap 2dup redundant-replace?
[ 2drop ] [ untranslate-loc ##replace ] if
] assoc-each ;
: clear-state ( state -- )
[ locs>vregs>> clear-assoc ]
[ actual-locs>vregs>> clear-assoc ]
[ changed-locs>> clear-assoc ]
tri ;
ERROR: poisoned-state state ;
: sync-state ( -- )
state get {
[ dup poisoned?>> [ poisoned-state ] [ drop ] if ]
[ save-changed-locs ]
[ clear-state ]
} cleave ;
: poison-state ( -- ) state get t >>poisoned? drop ;
! Abstract interpretation
GENERIC: visit ( insn -- )
! Instructions which don't have any effect on the stack
UNION: neutral-insn
##flushable
##effect ;
M: neutral-insn visit , ;
UNION: sync-if-back-edge
##branch
##conditional-branch
##compare-imm-branch
##dispatch
##loop-entry ;
SYMBOL: local-only?
t local-only? set-global
: back-edge? ( from to -- ? )
[ number>> ] bi@ > ;
: sync-state? ( -- ? )
basic-block get successors>>
[ [ predecessors>> ] keep '[ _ back-edge? ] any? ] any?
local-only? get or ;
M: sync-if-back-edge visit
sync-state? [ sync-state ] when , ;
: adjust-d ( n -- ) state get [ + ] change-ds-height drop ;
M: ##inc-d visit [ , ] [ n>> adjust-d ] bi ;
: adjust-r ( n -- ) state get [ + ] change-rs-height drop ;
M: ##inc-r visit [ , ] [ n>> adjust-r ] bi ;
: eliminate-peek ( dst src -- )
! the requested stack location is already in 'src'
[ ##copy ] [ swap copies get set-at ] 2bi ;
M: ##peek visit
dup
[ dst>> ] [ loc>> translate-loc ] bi
dup loc>vreg dup [ nip eliminate-peek drop ] [ drop record-peek , ] if ;
M: ##replace visit
[ src>> resolve ] [ loc>> translate-loc ] bi
record-replace ;
M: ##copy visit
[ call-next-method ] [ record-copy ] bi ;
M: ##call visit
[ call-next-method ] [ height>> adjust-d ] bi ;
! Instructions that poison the stack state
UNION: poison-insn
##jump
##return
##callback-return
##fixnum-mul-tail
##fixnum-add-tail
##fixnum-sub-tail ;
M: poison-insn visit call-next-method poison-state ;
! Instructions that kill all live vregs
UNION: kill-vreg-insn
poison-insn
##stack-frame
##call
##prologue
##epilogue
##fixnum-mul
##fixnum-add
##fixnum-sub
##alien-invoke
##alien-indirect ;
M: kill-vreg-insn visit sync-state , ;
: visit-alien-node ( node -- )
params>> [ out-d>> length ] [ in-d>> length ] bi - adjust-d ;
M: ##alien-invoke visit
[ call-next-method ] [ visit-alien-node ] bi ;
M: ##alien-indirect visit
[ call-next-method ] [ visit-alien-node ] bi ;
M: ##alien-callback visit , ;
! Maps basic-blocks to states
SYMBOLS: state-in state-out ;
: initial-state ( bb states -- state ) 2drop <state> ;
: single-predecessor ( bb states -- state ) nip first clone ;
ERROR: must-equal-failed seq ;
: must-equal ( seq -- elt )
dup all-equal? [ first ] [ must-equal-failed ] if ;
: merge-heights ( state predecessors states -- state )
nip
[ [ ds-height>> ] map must-equal >>ds-height ]
[ [ rs-height>> ] map must-equal >>rs-height ] bi ;
: insert-peek ( predecessor loc -- vreg )
! XXX critical edges
'[ _ ^^peek ] add-instructions ;
: merge-loc ( predecessors locs>vregs loc -- vreg )
! Insert a ##phi in the current block where the input
! is the vreg storing loc from each predecessor block
[ '[ [ _ ] dip at ] map ] keep
'[ [ ] [ _ insert-peek ] ?if ] 2map
dup all-equal? [ first ] [ ^^phi ] if ;
: (merge-locs) ( predecessors assocs -- assoc )
dup [ keys ] map concat prune
[ [ 2nip ] [ merge-loc ] 3bi ] with with
H{ } map>assoc ;
: merge-locs ( state predecessors states -- state )
[ locs>vregs>> ] map (merge-locs) >>locs>vregs ;
: merge-loc' ( locs>vregs loc -- vreg )
! Insert a ##phi in the current block where the input
! is the vreg storing loc from each predecessor block
'[ [ _ ] dip at ] map
dup all-equal? [ first ] [ drop f ] if ;
: merge-actual-locs ( state predecessors states -- state )
nip
[ actual-locs>vregs>> ] map
dup [ keys ] map concat prune
[ [ nip ] [ merge-loc' ] 2bi ] with
H{ } map>assoc
[ nip ] assoc-filter
>>actual-locs>vregs ;
: merge-changed-locs ( state predecessors states -- state )
nip [ changed-locs>> ] map assoc-combine >>changed-locs ;
ERROR: cannot-merge-poisoned states ;
: multiple-predecessors ( bb states -- state )
dup [ not ] any? [
[ <state> ] 2dip
sift merge-heights
] [
dup [ poisoned?>> ] any? [
cannot-merge-poisoned
] [
[ state new ] 2dip
[ predecessors>> ] dip
{
[ merge-locs ]
[ merge-actual-locs ]
[ merge-heights ]
[ merge-changed-locs ]
} 2cleave
] if
] if ;
: merge-states ( bb states -- state )
! If any states are poisoned, save all registers
! to the stack in each branch
dup length {
{ 0 [ initial-state ] }
{ 1 [ single-predecessor ] }
[ drop multiple-predecessors ]
} case ;
: block-in-state ( bb -- states )
dup predecessors>> state-out get '[ _ at ] map merge-states ;
: set-block-in-state ( state bb -- )
[ clone ] dip state-in get set-at ;
: set-block-out-state ( state bb -- )
[ clone ] dip state-out get set-at ;
: visit-block ( bb -- )
! block-in-state may add phi nodes at the start of the basic block
! so we wrap the whole thing with a 'make'
[
dup basic-block set
dup block-in-state
[ swap set-block-in-state ] [
state [
[ instructions>> [ visit ] each ]
[ [ state get ] dip set-block-out-state ]
[ ]
tri
] with-variable
] 2bi
] V{ } make >>instructions drop ;
: stack-analysis ( cfg -- cfg' )
[
H{ } clone copies set
H{ } clone state-in set
H{ } clone state-out set
dup [ visit-block ] each-basic-block
] with-scope ;