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

238 lines
6.3 KiB
Factor

! Copyright (C) 2009 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: accessors assocs kernel namespaces math sequences fry deques
search-deques dlists sets make combinators compiler.cfg.copy-prop
compiler.cfg.def-use compiler.cfg.instructions compiler.cfg.registers
compiler.cfg.rpo ;
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 vregs>locs changed-locs d-height r-height poisoned? ;
: <state> ( -- state )
state new
H{ } clone >>locs>vregs
H{ } clone >>vregs>locs
H{ } clone >>changed-locs
0 >>d-height
0 >>r-height ;
M: state clone
call-next-method
[ clone ] change-locs>vregs
[ clone ] change-vregs>locs
[ clone ] change-changed-locs ;
: loc>vreg ( loc -- vreg ) state get locs>vregs>> at ;
: record-peek ( dst loc -- )
state get
[ locs>vregs>> set-at ]
[ swapd vregs>locs>> set-at ]
3bi ;
: delete-old-vreg ( loc -- )
state get locs>vregs>> at [ state get vregs>locs>> delete-at ] when* ;
: changed-loc ( loc -- )
state get changed-locs>> conjoin ;
: redundant-replace? ( src loc -- ? )
loc>vreg = ;
: record-replace ( src loc -- )
! Locs are not single assignment, which means we have to forget
! that the previous vreg, if any, points at this loc. Also, record
! that the loc changed so that all the right ##replace instructions
! are emitted at a sync point.
2dup redundant-replace? [ 2drop ] [
dup delete-old-vreg dup changed-loc record-peek
] if ;
: save-changed-locs ( state -- )
[ changed-locs>> ] [ locs>vregs>> ] bi '[
_ at swap 2dup redundant-replace?
[ 2drop ] [ ##replace ] if
] assoc-each ;
: clear-state ( state -- )
{
[ 0 >>d-height drop ]
[ 0 >>r-height drop ]
[ changed-locs>> clear-assoc ]
[ locs>vregs>> clear-assoc ]
[ vregs>locs>> clear-assoc ]
} cleave ;
: sync-state ( -- )
! also: update height
! but first, sync outputs
state get {
[ save-changed-locs ]
[ d-height>> dup 0 = [ drop ] [ ##inc-d ] if ]
[ r-height>> dup 0 = [ drop ] [ ##inc-r ] if ]
[ clear-state ]
} cleave ;
: poison-state ( -- ) state get t >>poisoned? drop ;
GENERIC: translate-loc ( loc -- loc' )
M: ds-loc translate-loc n>> state get d-height>> + <ds-loc> ;
M: rs-loc translate-loc n>> state get r-height>> + <rs-loc> ;
! Abstract interpretation
GENERIC: visit ( insn -- )
! Instructions which don't have any effect on the stack
UNION: neutral-insn
##flushable
##effect
##branch
##loop-entry
##conditional-branch ;
M: neutral-insn visit , ;
: adjust-d ( n -- ) state get [ + ] change-d-height drop ;
M: ##inc-d visit n>> adjust-d ;
: adjust-r ( n -- ) state get [ + ] change-r-height drop ;
M: ##inc-r visit n>> adjust-r ;
: 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 ] [ poison-state ] if* ] bi ;
M: ##fixnum-mul visit
call-next-method -1 adjust-d ;
M: ##fixnum-add visit
call-next-method -1 adjust-d ;
M: ##fixnum-sub visit
call-next-method -1 adjust-d ;
! Instructions that poison the stack state
UNION: poison-insn
##jump
##return
##dispatch
##dispatch-label
##alien-callback
##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 ;
! Basic blocks we still need to look at
SYMBOL: work-list
: add-to-work-list ( basic-block -- )
work-list get push-front ;
! Maps basic-blocks to states
SYMBOLS: state-in state-out ;
: merge-states ( seq -- state )
[ <state> ] [ first ] if-empty ;
: block-in-state ( bb -- states )
predecessors>> state-out get '[ _ at ] map merge-states ;
: maybe-set-at ( value key assoc -- changed? )
3dup at* [ = [ 3drop f ] [ set-at t ] if ] [ 2drop set-at t ] if ;
: set-block-in-state ( state b -- )
state-in get set-at ;
: set-block-out-state ( bb state -- changed? )
swap state-out get maybe-set-at ;
: finish-block ( bb state -- )
[ drop ] [ set-block-out-state ] 2bi
[ successors>> [ add-to-work-list ] each ] [ drop ] if ;
: visit-block ( bb -- )
dup block-in-state
[ swap set-block-in-state ] [
state [
[ [ [ [ visit ] each ] V{ } make ] change-instructions drop ]
[ state get finish-block ]
bi
] with-variable
] 2bi ;
: visit-blocks ( bb -- )
reverse-post-order work-list get
[ '[ _ push-front ] each ] [ [ visit-block ] slurp-deque ] bi ;
: optimize-stack ( cfg -- cfg )
[
H{ } clone copies set
H{ } clone state-in set
H{ } clone state-out set
<hashed-dlist> work-list set
dup entry>> visit-blocks
] with-scope ;
! To do:
! - implement merge-states
! - insert loads to convert partially available values into available values
! if any state is poisoned, then we need to sync in every predecessor that didn't sync
! and begin with a new state.
! if heights differ, throw an error.
! changed-locs is the union of the changed-locs of all predecessors
! locs>vregs: take the union, then for each predecessor, diff its locs>vregs against the union.
! those are the ones that need to be loaded in.
! think about phi insertion.