1 ! Copyright (C) 2008, 2010 Slava Pestov.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: accessors arrays assocs combinators.short-circuit
4 compiler.cfg.comparisons compiler.cfg.instructions
5 compiler.cfg.representations.preferred compiler.cfg.rpo
6 compiler.cfg.utilities cpu.architecture fry kernel locals math
7 namespaces sequences sets ;
9 IN: compiler.cfg.alias-analysis
11 ! Local copy propagation
14 : resolve ( vreg -- vreg ) copies get ?at drop ;
16 : record-copy ( ##copy -- )
17 [ src>> resolve ] [ dst>> ] bi copies get set-at ; inline
19 ! Map vregs -> alias classes
22 ! Map alias classes -> sequence of vregs
25 ! Alias class for objects which are loaded from the data stack
26 ! or other object slots. We pessimistically assume that they
27 ! can all alias each other.
30 : ac>vregs ( ac -- vregs )
31 acs>vregs get [ drop V{ } clone ] cache ;
33 : vreg>ac ( vreg -- ac )
34 #! Only vregs produced by ##allot, ##peek and ##slot can
35 #! ever be used as valid inputs to ##slot and ##set-slot,
36 #! so we assert this fact by not giving alias classes to
38 vregs>acs get [ heap-ac get [ ac>vregs push ] keep ] cache ;
40 : aliases ( vreg -- vregs )
41 #! All vregs which may contain the same value as vreg.
44 : each-alias ( vreg quot -- )
45 [ aliases ] dip each ; inline
47 : merge-acs ( vreg into -- )
51 [ vregs>acs get '[ [ _ ] dip _ set-at ] each ]
56 ! Map vregs -> slot# -> vreg
59 ! Maps vreg -> slot# -> insn# of last store or f
62 ! A set of insn#s of dead stores
65 : dead-store ( insn# -- ) dead-stores get adjoin ;
67 ERROR: vreg-not-new vreg ;
69 :: set-ac ( vreg ac -- )
70 #! Set alias class of newly-seen vreg.
71 vreg vregs>acs get key? [ vreg vreg-not-new ] when
72 ac vreg vregs>acs get set-at
73 vreg ac ac>vregs push ;
75 : live-slot ( slot#/f vreg -- vreg' )
76 #! If the slot number is unknown, we never reuse a previous
78 over [ live-slots get at at ] [ 2drop f ] if ;
80 : load-constant-slot ( value slot# vreg -- )
81 live-slots get [ drop H{ } clone ] cache set-at ;
83 : load-slot ( value slot#/f vreg -- )
84 over [ load-constant-slot ] [ 3drop ] if ;
86 : record-constant-slot ( slot# vreg -- )
87 #! A load can potentially read every store of this slot#
88 #! in that alias class.
89 [ recent-stores get at delete-at ] with each-alias ;
91 : record-computed-slot ( vreg -- )
92 #! Computed load is like a load of every slot touched so far
93 [ recent-stores get at clear-assoc ] each-alias ;
95 :: remember-slot ( value slot# vreg -- )
97 slot# vreg record-constant-slot
98 value slot# vreg load-constant-slot
99 ] [ vreg record-computed-slot ] if ;
104 ac-counter [ dup 1 + ] change ;
106 : set-new-ac ( vreg -- ) next-ac set-ac ;
108 : kill-constant-set-slot ( slot# vreg -- )
109 [ live-slots get at delete-at ] with each-alias ;
111 : recent-stores-of ( vreg -- assoc )
112 recent-stores get [ drop H{ } clone ] cache ;
114 :: record-constant-set-slot ( insn# slot# vreg -- )
115 vreg recent-stores-of :> recent-stores
116 slot# recent-stores at [ dead-store ] when*
117 insn# slot# recent-stores set-at ;
119 : kill-computed-set-slot ( vreg -- )
120 [ live-slots get at clear-assoc ] each-alias ;
122 :: remember-set-slot ( insn# slot# vreg -- )
124 insn# slot# vreg record-constant-set-slot
125 slot# vreg kill-constant-set-slot
126 ] [ vreg kill-computed-set-slot ] if ;
128 : init-alias-analysis ( -- )
129 H{ } clone vregs>acs namespaces:set
130 H{ } clone acs>vregs namespaces:set
131 H{ } clone live-slots namespaces:set
132 H{ } clone copies namespaces:set
133 H{ } clone recent-stores namespaces:set
134 HS{ } clone dead-stores namespaces:set
135 0 ac-counter namespaces:set ;
137 GENERIC: insn-slot# ( insn -- slot#/f )
138 GENERIC: insn-object ( insn -- vreg )
140 M: ##slot insn-slot# drop f ;
141 M: ##slot-imm insn-slot# slot>> ;
142 M: ##set-slot insn-slot# drop f ;
143 M: ##set-slot-imm insn-slot# slot>> ;
144 M: ##alien-global insn-slot# [ library>> ] [ symbol>> ] bi 2array ;
145 M: ##vm-field insn-slot# offset>> ;
146 M: ##set-vm-field insn-slot# offset>> ;
148 M: ##slot insn-object obj>> resolve ;
149 M: ##slot-imm insn-object obj>> resolve ;
150 M: ##set-slot insn-object obj>> resolve ;
151 M: ##set-slot-imm insn-object obj>> resolve ;
152 M: ##alien-global insn-object drop ##alien-global ;
153 M: ##vm-field insn-object drop ##vm-field ;
154 M: ##set-vm-field insn-object drop ##vm-field ;
156 GENERIC: analyze-aliases ( insn -- insn' )
158 M: insn analyze-aliases ;
160 : def-acs ( insn -- insn' )
161 ! If an instruction defines a value with a non-integer
162 ! representation it means that the value will be boxed
163 ! anywhere its used as a tagged pointer. Boxing allocates
164 ! a new value, except boxing instructions haven't been
167 { int-rep tagged-rep } member?
168 [ drop ] [ set-new-ac ] if
171 M: vreg-insn analyze-aliases
174 M: allocation-insn analyze-aliases
175 #! A freshly allocated object is distinct from any other
177 dup dst>> set-new-ac ;
179 M: ##box-displaced-alien analyze-aliases
181 [ base>> heap-ac get merge-acs ] bi ;
183 M: read-insn analyze-aliases
185 dup [ dst>> ] [ insn-slot# ] [ insn-object ] tri
187 [ 2nip <copy> analyze-aliases nip ]
188 [ drop remember-slot ]
191 : idempotent? ( value slot#/f vreg -- ? )
192 #! Are we storing a value back to the same slot it was read
196 M:: write-insn analyze-aliases ( insn -- insn )
197 insn src>> resolve :> src
198 insn insn-slot# :> slot#
199 insn insn-object :> vreg
200 insn insn#>> :> insn#
202 src slot# vreg idempotent? [ insn# dead-store ] [
203 src heap-ac get merge-acs
204 insn insn#>> slot# vreg remember-set-slot
205 src slot# vreg load-slot
210 M: ##copy analyze-aliases
211 #! The output vreg gets the same alias class as the input
212 #! vreg, since they both contain the same value.
215 : useless-compare? ( insn -- ? )
218 [ [ src1>> ] [ src2>> ] bi [ resolve vreg>ac ] same? not ]
221 M: ##compare analyze-aliases
223 dup useless-compare? [
224 dst>> f ##load-reference new-insn
228 : clear-live-slots ( -- )
229 heap-ac get ac>vregs [ live-slots get at clear-assoc ] each ;
231 : clear-recent-stores ( -- )
232 recent-stores get values [ clear-assoc ] each ;
234 M: gc-map-insn analyze-aliases
235 ! Can't use call-next-method here because of a limitation, gah
237 clear-recent-stores ;
239 M: alien-call-insn analyze-aliases
244 GENERIC: eliminate-dead-stores ( insn -- ? )
246 M: ##set-slot-imm eliminate-dead-stores
247 insn#>> dead-stores get in? not ;
249 M: insn eliminate-dead-stores drop t ;
251 : reset-alias-analysis ( -- )
252 recent-stores get clear-assoc
253 vregs>acs get clear-assoc
254 acs>vregs get clear-assoc
255 live-slots get clear-assoc
256 copies get clear-assoc
257 dead-stores get clear-set
259 next-ac heap-ac namespaces:set
260 ##vm-field set-new-ac
261 ##alien-global set-new-ac ;
263 : alias-analysis-step ( insns -- insns' )
265 [ 0 [ [ insn#<< ] [ drop 1 + ] 2bi ] reduce drop ]
266 [ [ analyze-aliases ] map! [ eliminate-dead-stores ] filter! ] bi ;
268 : alias-analysis ( cfg -- )
270 [ alias-analysis-step ] simple-optimization ;