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compiler.cfg.alias-analysis: dead store elimination was too aggressive, can't eliminate dead stores across a GC call even for fresh allocations because GC will see uninitialized data

db4
Slava Pestov 2010-09-06 16:57:56 -07:00
parent db61c9341b
commit a605d5c9c9
2 changed files with 116 additions and 17 deletions
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91
basis/compiler/cfg/alias-analysis/alias-analysis-tests.factor
View File

@ -288,8 +288,8 @@ IN: compiler.cfg.alias-analysis.tests
} test-alias-analysis
] unit-test
! We can't make any assumptions about heap-ac between alien
! calls, since they might callback into Factor code
! We can't make any assumptions about heap-ac between
! instructions which can call back into Factor code
[
V{
T{ ##peek f 0 D 0 }
@ -359,3 +359,90 @@ IN: compiler.cfg.alias-analysis.tests
T{ ##set-slot-imm f 1 0 1 0 }
} test-alias-analysis
] unit-test
! We can't eliminate stores on any alias class across a GC-ing
! instruction
[
V{
T{ ##allot f 0 }
T{ ##slot-imm f 1 0 1 0 }
T{ ##alien-invoke f { } { } { } { } 0 0 "free" }
T{ ##copy f 2 1 any-rep }
}
] [
V{
T{ ##allot f 0 }
T{ ##slot-imm f 1 0 1 0 }
T{ ##alien-invoke f { } { } { } { } 0 0 "free" }
T{ ##slot-imm f 2 0 1 0 }
} test-alias-analysis
] unit-test
[
V{
T{ ##allot f 0 }
T{ ##peek f 1 D 1 }
T{ ##set-slot-imm f 1 0 1 0 }
T{ ##alien-invoke f { } { } { } { } 0 0 "free" }
T{ ##copy f 2 1 any-rep }
}
] [
V{
T{ ##allot f 0 }
T{ ##peek f 1 D 1 }
T{ ##set-slot-imm f 1 0 1 0 }
T{ ##alien-invoke f { } { } { } { } 0 0 "free" }
T{ ##slot-imm f 2 0 1 0 }
} test-alias-analysis
] unit-test
[
V{
T{ ##allot f 0 }
T{ ##peek f 1 D 1 }
T{ ##peek f 2 D 2 }
T{ ##set-slot-imm f 1 0 1 0 }
T{ ##alien-invoke f { } { } { } { } 0 0 "free" }
T{ ##set-slot-imm f 2 0 1 0 }
}
] [
V{
T{ ##allot f 0 }
T{ ##peek f 1 D 1 }
T{ ##peek f 2 D 2 }
T{ ##set-slot-imm f 1 0 1 0 }
T{ ##alien-invoke f { } { } { } { } 0 0 "free" }
T{ ##set-slot-imm f 2 0 1 0 }
} test-alias-analysis
] unit-test
[
V{
T{ ##allot f 0 }
T{ ##slot-imm f 1 0 1 0 }
T{ ##alien-invoke f { } { } { } { } 0 0 "free" }
}
] [
V{
T{ ##allot f 0 }
T{ ##slot-imm f 1 0 1 0 }
T{ ##alien-invoke f { } { } { } { } 0 0 "free" }
T{ ##set-slot-imm f 1 0 1 0 }
} test-alias-analysis
] unit-test
! Make sure that gc-map-insns which are also vreg-insns are
! handled properly
[
V{
T{ ##allot f 0 }
T{ ##alien-indirect f { } { } { { 2 double-rep 0 } } { } 0 0 "free" }
T{ ##set-slot-imm f 2 0 1 0 }
}
] [
V{
T{ ##allot f 0 }
T{ ##alien-indirect f { } { } { { 2 double-rep 0 } } { } 0 0 "free" }
T{ ##set-slot-imm f 2 0 1 0 }
} test-alias-analysis
] unit-test

42
basis/compiler/cfg/alias-analysis/alias-analysis.factor
View File

@ -218,7 +218,7 @@ GENERIC: analyze-aliases ( insn -- insn' )
M: insn analyze-aliases ;
M: vreg-insn analyze-aliases
: def-acs ( insn -- insn' )
! If an instruction defines a value with a non-integer
! representation it means that the value will be boxed
! anywhere its used as a tagged pointer. Boxing allocates
@ -229,6 +229,9 @@ M: vreg-insn analyze-aliases
[ set-heap-ac ] [ set-new-ac ] if
] each-def-rep ;
M: vreg-insn analyze-aliases
def-acs ;
M: ##phi analyze-aliases
dup dst>> set-heap-ac ;
@ -286,6 +289,29 @@ M: ##compare analyze-aliases
analyze-aliases
] when ;
: clear-live-slots ( -- )
heap-ac get ac>vregs [ live-slots get at clear-assoc ] each ;
: clear-recent-stores ( -- )
recent-stores get values [ clear-assoc ] each ;
M: gc-map-insn analyze-aliases
! Can't use call-next-method here because of a limitation, gah
def-acs
clear-recent-stores ;
M: factor-call-insn analyze-aliases
def-acs
clear-recent-stores
clear-live-slots ;
GENERIC: eliminate-dead-stores ( insn -- ? )
M: ##set-slot-imm eliminate-dead-stores
insn#>> dead-stores get in? not ;
M: insn eliminate-dead-stores drop t ;
: reset-alias-analysis ( -- )
recent-stores get clear-assoc
vregs>acs get clear-assoc
@ -298,20 +324,6 @@ M: ##compare analyze-aliases
\ ##vm-field set-new-ac
\ ##alien-global set-new-ac ;
M: factor-call-insn analyze-aliases
call-next-method
heap-ac get ac>vregs [
[ live-slots get at clear-assoc ]
[ recent-stores get at clear-assoc ] bi
] each ;
GENERIC: eliminate-dead-stores ( insn -- ? )
M: ##set-slot-imm eliminate-dead-stores
insn#>> dead-stores get in? not ;
M: insn eliminate-dead-stores drop t ;
: alias-analysis-step ( insns -- insns' )
reset-alias-analysis
[ local-live-in [ set-heap-ac ] each ]