From 949b527ed58167bf6d667108ecb00cd678603f44 Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@shill.local>
Date: Fri, 10 Jul 2009 07:52:20 -0500
Subject: [PATCH 1/5] Help lint fixes for urls.encoding and mongodb.driver

---
 basis/urls/encoding/encoding-docs.factor | 2 +-
 extra/mongodb/driver/driver-docs.factor  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/basis/urls/encoding/encoding-docs.factor b/basis/urls/encoding/encoding-docs.factor
index 82ab3d1f69..a021bd6d23 100644
--- a/basis/urls/encoding/encoding-docs.factor
+++ b/basis/urls/encoding/encoding-docs.factor
@@ -26,7 +26,7 @@ HELP: assoc>query
         "USING: io urls.encoding ;"
         "{ { \"from\" \"Lead\" } { \"to\" \"Gold, please\" } }"
         "assoc>query print"
-        "from=Lead&to=Gold%2c%20please"
+        "from=Lead&to=Gold%2C%20please"
     }
 } ;
 
diff --git a/extra/mongodb/driver/driver-docs.factor b/extra/mongodb/driver/driver-docs.factor
index e8f726374c..532dfe1dce 100644
--- a/extra/mongodb/driver/driver-docs.factor
+++ b/extra/mongodb/driver/driver-docs.factor
@@ -76,7 +76,7 @@ HELP: count
 
 HELP: create-collection
 { $values
-  { "name" "collection name" }
+  { "name/collection" "collection name" }
 }
 { $description "Creates a new collection with the given name." } ;
 

From 608fb054f26bc006037d8cb4dd2762136b8ab26b Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@slava-pestovs-macbook-pro.local>
Date: Sun, 12 Jul 2009 22:22:46 -0500
Subject: [PATCH 2/5] compiler.cfg: Some code cleanups, update stack-analysis
 and phi-insertion to work on CFGs with critical edges

---
 .../branch-folding-tests.factor               |  5 +-
 .../cfg/branch-folding/branch-folding.factor  |  4 +-
 basis/compiler/cfg/cfg.factor                 | 36 +---------
 .../cfg/optimizer/optimizer-tests.factor      | 11 +++-
 .../phi-elimination-tests.factor              | 10 ++-
 .../phi-elimination/phi-elimination.factor    | 13 ++--
 .../stack-analysis/merge/merge-tests.factor   | 47 ++++++++-----
 .../cfg/stack-analysis/merge/merge.factor     | 66 +++++++++++--------
 .../stack-analysis-tests.factor               | 12 ++--
 .../cfg/stack-analysis/stack-analysis.factor  | 22 ++++++-
 basis/compiler/cfg/tco/tco.factor             |  5 +-
 .../useless-conditionals.factor               |  5 +-
 basis/compiler/cfg/utilities/utilities.factor | 58 ++++++++++++++--
 13 files changed, 185 insertions(+), 109 deletions(-)

diff --git a/basis/compiler/cfg/branch-folding/branch-folding-tests.factor b/basis/compiler/cfg/branch-folding/branch-folding-tests.factor
index 964620d2d3..8ae1f6b75b 100644
--- a/basis/compiler/cfg/branch-folding/branch-folding-tests.factor
+++ b/basis/compiler/cfg/branch-folding/branch-folding-tests.factor
@@ -40,7 +40,10 @@ test-diamond
 [ 1 ] [ 1 get successors>> length ] unit-test
 [ t ] [ 1 get successors>> first 3 get eq? ] unit-test
 
-[ T{ ##copy f V int-regs 3 V int-regs 2 } ] [ 3 get instructions>> second ] unit-test
+[ T{ ##copy f V int-regs 3 V int-regs 2 } ]
+[ 3 get successors>> first instructions>> first ]
+unit-test
+
 [ 2 ] [ 4 get instructions>> length ] unit-test
 
 V{
diff --git a/basis/compiler/cfg/branch-folding/branch-folding.factor b/basis/compiler/cfg/branch-folding/branch-folding.factor
index 627db63c9f..2432849a9a 100644
--- a/basis/compiler/cfg/branch-folding/branch-folding.factor
+++ b/basis/compiler/cfg/branch-folding/branch-folding.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors combinators.short-circuit kernel sequences vectors
-compiler.cfg.instructions compiler.cfg.rpo ;
+compiler.cfg.instructions compiler.cfg.rpo compiler.cfg ;
 IN: compiler.cfg.branch-folding
 
 ! Fold comparisons where both inputs are the same. Predecessors must be
@@ -27,4 +27,4 @@ IN: compiler.cfg.branch-folding
         dup fold-branch?
         [ fold-branch ] [ drop ] if
     ] each-basic-block
-    f >>post-order ;
\ No newline at end of file
+    cfg-changed ;
\ No newline at end of file
diff --git a/basis/compiler/cfg/cfg.factor b/basis/compiler/cfg/cfg.factor
index 12a1180d40..f856efac78 100644
--- a/basis/compiler/cfg/cfg.factor
+++ b/basis/compiler/cfg/cfg.factor
@@ -1,9 +1,6 @@
 ! Copyright (C) 2008, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel arrays vectors accessors assocs sets
-namespaces math make fry sequences
-combinators.short-circuit
-compiler.cfg.instructions ;
+USING: kernel math vectors arrays accessors namespaces ;
 IN: compiler.cfg
 
 TUPLE: basic-block < identity-tuple
@@ -22,39 +19,12 @@ M: basic-block hashcode* nip id>> ;
         V{ } clone >>predecessors
         \ basic-block counter >>id ;
 
-: empty-block? ( bb -- ? )
-    instructions>> {
-        [ length 1 = ]
-        [ first ##branch? ]
-    } 1&& ;
-
-SYMBOL: visited
-
-: (skip-empty-blocks) ( bb -- bb' )
-    dup visited get key? [
-        dup empty-block? [
-            dup visited get conjoin
-            successors>> first (skip-empty-blocks)
-        ] when
-    ] unless ;
-
-: skip-empty-blocks ( bb -- bb' )
-    H{ } clone visited [ (skip-empty-blocks) ] with-variable ;
-
-: add-instructions ( bb quot -- )
-    [ instructions>> building ] dip '[
-        building get pop
-        _ dip
-        building get push
-    ] with-variable ; inline
-
-: back-edge? ( from to -- ? )
-    [ number>> ] bi@ > ;
-
 TUPLE: cfg { entry basic-block } word label spill-counts post-order ;
 
 : <cfg> ( entry word label -- cfg ) f f cfg boa ;
 
+: cfg-changed ( cfg -- cfg ) f >>post-order ; inline
+
 TUPLE: mr { instructions array } word label ;
 
 : <mr> ( instructions word label -- mr )
diff --git a/basis/compiler/cfg/optimizer/optimizer-tests.factor b/basis/compiler/cfg/optimizer/optimizer-tests.factor
index 93adc4c0f9..f585d80d72 100755
--- a/basis/compiler/cfg/optimizer/optimizer-tests.factor
+++ b/basis/compiler/cfg/optimizer/optimizer-tests.factor
@@ -1,7 +1,7 @@
 USING: accessors arrays compiler.cfg.checker
 compiler.cfg.debugger compiler.cfg.def-use
 compiler.cfg.instructions fry kernel kernel.private math
-math.private sbufs sequences sequences.private sets
+math.partial-dispatch math.private sbufs sequences sequences.private sets
 slots.private strings tools.test vectors layouts ;
 IN: compiler.cfg.optimizer.tests
 
@@ -31,6 +31,15 @@ IN: compiler.cfg.optimizer.tests
     [ [ 2 fixnum+ ] when 3 ]
     [ [ 2 fixnum- ] when 3 ]
     [ 10000 [ ] times ]
+    [
+        over integer? [
+            over dup 16 <-integer-fixnum
+            [ 0 >=-integer-fixnum ] [ drop f ] if [
+                nip dup
+                [ ] [ ] if
+            ] [ 2drop f ] if
+        ] [ 2drop f ] if
+    ]
 } [
     [ [ ] ] dip '[ _ test-mr first check-mr ] unit-test
 ] each
diff --git a/basis/compiler/cfg/phi-elimination/phi-elimination-tests.factor b/basis/compiler/cfg/phi-elimination/phi-elimination-tests.factor
index 4577e70997..2dd75df693 100644
--- a/basis/compiler/cfg/phi-elimination/phi-elimination-tests.factor
+++ b/basis/compiler/cfg/phi-elimination/phi-elimination-tests.factor
@@ -35,6 +35,12 @@ test-diamond
 
 [ ] [ cfg new 0 get >>entry eliminate-phis drop ] unit-test
 
-[ T{ ##copy f V int-regs 3 V int-regs 1 } ] [ 2 get instructions>> second ] unit-test
-[ T{ ##copy f V int-regs 3 V int-regs 2 } ] [ 3 get instructions>> second ] unit-test
+[ T{ ##copy f V int-regs 3 V int-regs 1 } ]
+[ 2 get successors>> first instructions>> first ]
+unit-test
+
+[ T{ ##copy f V int-regs 3 V int-regs 2 } ]
+[ 3 get successors>> first instructions>> first ]
+unit-test
+
 [ 2 ] [ 4 get instructions>> length ] unit-test
\ No newline at end of file
diff --git a/basis/compiler/cfg/phi-elimination/phi-elimination.factor b/basis/compiler/cfg/phi-elimination/phi-elimination.factor
index 9c2f0adafd..7e184a9b53 100644
--- a/basis/compiler/cfg/phi-elimination/phi-elimination.factor
+++ b/basis/compiler/cfg/phi-elimination/phi-elimination.factor
@@ -1,7 +1,8 @@
 ! Copyright (C) 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors assocs fry kernel sequences
-compiler.cfg compiler.cfg.instructions compiler.cfg.rpo ;
+USING: accessors assocs fry kernel sequences namespaces
+compiler.cfg compiler.cfg.instructions compiler.cfg.rpo
+compiler.cfg.utilities ;
 IN: compiler.cfg.phi-elimination
 
 : insert-copy ( predecessor input output -- )
@@ -11,7 +12,11 @@ IN: compiler.cfg.phi-elimination
     [ inputs>> ] [ dst>> ] bi '[ _ insert-copy ] assoc-each ;
 
 : eliminate-phi-step ( bb -- )
-    instructions>> [ dup ##phi? [ eliminate-phi f ] [ drop t ] if ] filter-here ;
+    H{ } clone added-instructions set
+    [ instructions>> [ dup ##phi? [ eliminate-phi f ] [ drop t ] if ] filter-here ]
+    [ insert-basic-blocks ]
+    bi ;
 
 : eliminate-phis ( cfg -- cfg' )
-    dup [ eliminate-phi-step ] each-basic-block ;
\ No newline at end of file
+    dup [ eliminate-phi-step ] each-basic-block
+    cfg-changed ;
\ No newline at end of file
diff --git a/basis/compiler/cfg/stack-analysis/merge/merge-tests.factor b/basis/compiler/cfg/stack-analysis/merge/merge-tests.factor
index 14a81958a9..e67f6b5143 100644
--- a/basis/compiler/cfg/stack-analysis/merge/merge-tests.factor
+++ b/basis/compiler/cfg/stack-analysis/merge/merge-tests.factor
@@ -2,7 +2,7 @@ IN: compiler.cfg.stack-analysis.merge.tests
 USING: compiler.cfg.stack-analysis.merge tools.test arrays accessors
 compiler.cfg.instructions compiler.cfg.stack-analysis.state
 compiler.cfg compiler.cfg.registers compiler.cfg.debugger
-cpu.architecture make assocs
+cpu.architecture make assocs namespaces
 sequences kernel classes ;
 
 [
@@ -11,13 +11,15 @@ sequences kernel classes ;
 ] [
     <state>
 
-    <basic-block> V{ T{ ##branch } } >>instructions
-    <basic-block> V{ T{ ##branch } } >>instructions 2array
+    <basic-block> V{ T{ ##branch } } >>instructions dup 1 set
+    <basic-block> V{ T{ ##branch } } >>instructions dup 2 set 2array
 
     <state> H{ { D 0 V int-regs 0 } } >>locs>vregs
     <state> H{ { D 0 V int-regs 1 } } >>locs>vregs 2array
 
-    [ merge-locs locs>vregs>> keys ] { } make first inputs>> values
+    H{ } clone added-instructions set
+    V{ } clone added-phis set
+    merge-locs locs>vregs>> keys added-phis get values first
 ] unit-test
 
 [
@@ -26,15 +28,16 @@ sequences kernel classes ;
 ] [
     <state>
 
-    <basic-block> V{ T{ ##branch } } >>instructions
-    <basic-block> V{ T{ ##branch } } >>instructions 2array
+    <basic-block> V{ T{ ##branch } } >>instructions dup 1 set
+    <basic-block> V{ T{ ##branch } } >>instructions dup 2 set 2array
 
-    [
-        <state>
-        <state> H{ { D 0 V int-regs 1 } } >>locs>vregs 2array
+    <state>
+    <state> H{ { D 0 V int-regs 1 } } >>locs>vregs 2array
 
-        [ merge-locs locs>vregs>> keys ] { } make drop
-    ] keep first instructions>> first class
+    H{ } clone added-instructions set
+    V{ } clone added-phis set
+    [ merge-locs locs>vregs>> keys ] { } make drop
+    1 get added-instructions get at first class
 ] unit-test
 
 [
@@ -42,15 +45,17 @@ sequences kernel classes ;
 ] [
     <state>
 
-    <basic-block> V{ T{ ##branch } } >>instructions
-    <basic-block> V{ T{ ##branch } } >>instructions 2array
+    <basic-block> V{ T{ ##branch } } >>instructions dup 1 set
+    <basic-block> V{ T{ ##branch } } >>instructions dup 2 set 2array
 
-    [
-        <state> -1 >>ds-height
-        <state> 2array
+    H{ } clone added-instructions set
+    V{ } clone added-phis set
 
-        [ merge-ds-heights ds-height>> ] { } make drop
-    ] keep first instructions>> first class
+    <state> -1 >>ds-height
+    <state> 2array
+
+    [ merge-ds-heights ds-height>> ] { } make drop
+    1 get added-instructions get at first class
 ] unit-test
 
 [
@@ -63,6 +68,9 @@ sequences kernel classes ;
     <basic-block> V{ T{ ##branch } } >>instructions
     <basic-block> V{ T{ ##branch } } >>instructions 2array
 
+    H{ } clone added-instructions set
+    V{ } clone added-phis set
+    
     [
         <state> -1 >>ds-height H{ { D 1 V int-regs 0 } } >>locs>vregs
         <state> H{ { D 0 V int-regs 1 } } >>locs>vregs 2array
@@ -82,6 +90,9 @@ sequences kernel classes ;
     <basic-block> V{ T{ ##branch } } >>instructions
     <basic-block> V{ T{ ##branch } } >>instructions 2array
 
+    H{ } clone added-instructions set
+    V{ } clone added-phis set
+    
     [
         <state> -1 >>ds-height H{ { D -1 V int-regs 0 } } >>locs>vregs
         <state> -1 >>ds-height H{ { D -1 V int-regs 1 } } >>locs>vregs 2array
diff --git a/basis/compiler/cfg/stack-analysis/merge/merge.factor b/basis/compiler/cfg/stack-analysis/merge/merge.factor
index b6c443a2d3..cb0ad7d615 100644
--- a/basis/compiler/cfg/stack-analysis/merge/merge.factor
+++ b/basis/compiler/cfg/stack-analysis/merge/merge.factor
@@ -1,12 +1,11 @@
 ! Copyright (C) 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel assocs sequences accessors fry combinators grouping
-sets locals compiler.cfg compiler.cfg.hats compiler.cfg.instructions
-compiler.cfg.stack-analysis.state ;
+USING: kernel assocs sequences accessors fry combinators grouping sets
+arrays vectors locals namespaces make compiler.cfg compiler.cfg.hats
+compiler.cfg.instructions compiler.cfg.stack-analysis.state
+compiler.cfg.registers compiler.cfg.utilities cpu.architecture ;
 IN: compiler.cfg.stack-analysis.merge
 
-! XXX critical edges
-
 : initial-state ( bb states -- state ) 2drop <state> ;
 
 : single-predecessor ( bb states -- state ) nip first clone ;
@@ -27,14 +26,14 @@ IN: compiler.cfg.stack-analysis.merge
     [ nip first >>rs-height ]
     [ [ '[ _ save-rs-height ] add-instructions ] 2each ] if ;
 
-: assoc-map-values ( assoc quot -- assoc' )
+: assoc-map-keys ( assoc quot -- assoc' )
     '[ _ dip ] assoc-map ; inline
 
 : translate-locs ( assoc state -- assoc' )
-    '[ _ translate-loc ] assoc-map-values ;
+    '[ _ translate-loc ] assoc-map-keys ;
 
 : untranslate-locs ( assoc state -- assoc' )
-    '[ _ untranslate-loc ] assoc-map-values ;
+    '[ _ untranslate-loc ] assoc-map-keys ;
 
 : collect-locs ( loc-maps states -- assoc )
     ! assoc maps locs to sequences
@@ -45,12 +44,16 @@ IN: compiler.cfg.stack-analysis.merge
 : insert-peek ( predecessor loc state -- vreg )
     '[ _ _ translate-loc ^^peek ] add-instructions ;
 
+SYMBOL: added-phis
+
+: add-phi-later ( inputs -- vreg )
+    [ int-regs next-vreg dup ] dip 2array added-phis get push ;
+
 : merge-loc ( predecessors vregs loc state -- vreg )
     ! Insert a ##phi in the current block where the input
     ! is the vreg storing loc from each predecessor block
-    [ dup ] 3dip
     '[ [ ] [ _ _ insert-peek ] ?if ] 2map
-    dup all-equal? [ nip first ] [ zip ^^phi ] if ;
+    dup all-equal? [ first ] [ add-phi-later ] if ;
 
 :: merge-locs ( state predecessors states -- state )
     states [ locs>vregs>> ] map states collect-locs
@@ -77,30 +80,35 @@ IN: compiler.cfg.stack-analysis.merge
     over translate-locs
     >>changed-locs ;
 
-ERROR: cannot-merge-poisoned states ;
+:: insert-phis ( bb -- )
+    bb predecessors>> :> predecessors
+    [
+        added-phis get [| dst inputs |
+            dst predecessors inputs zip ##phi
+        ] assoc-each
+    ] V{ } make bb instructions>> over push-all
+    bb (>>instructions) ;
 
-: multiple-predecessors ( bb states -- state )
-    dup [ not ] any? [
-        2drop <state>
+:: multiple-predecessors ( bb states -- state )
+    states [ not ] any? [
+        <state>
     ] [
-        dup [ poisoned?>> ] any? [
-            cannot-merge-poisoned
-        ] [
-            [ state new ] 2dip
-            [ predecessors>> ] dip
-            {
-                [ merge-ds-heights ]
-                [ merge-rs-heights ]
-                [ merge-locs ]
-                [ nip merge-actual-locs ]
-                [ nip merge-changed-locs ]
-            } 2cleave
-        ] if
+        [
+            H{ } clone added-instructions set
+            V{ } clone added-phis set
+            bb predecessors>> :> predecessors
+            state new
+            predecessors states merge-ds-heights
+            predecessors states merge-rs-heights
+            predecessors states merge-locs
+            states merge-actual-locs
+            states merge-changed-locs
+            bb insert-basic-blocks
+            bb insert-phis
+        ] with-scope
     ] 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 ] }
diff --git a/basis/compiler/cfg/stack-analysis/stack-analysis-tests.factor b/basis/compiler/cfg/stack-analysis/stack-analysis-tests.factor
index cbc939b1f2..23b1098cd6 100644
--- a/basis/compiler/cfg/stack-analysis/stack-analysis-tests.factor
+++ b/basis/compiler/cfg/stack-analysis/stack-analysis-tests.factor
@@ -99,7 +99,7 @@ IN: compiler.cfg.stack-analysis.tests
 ! Correct height tracking
 [ t ] [
     [ pick [ <array> ] [ drop ] if swap ] test-stack-analysis eliminate-dead-code
-    reverse-post-order 3 swap nth
+    reverse-post-order 4 swap nth
     instructions>> [ ##peek? ] filter first2 [ loc>> ] [ loc>> ] bi*
     2array { D 1 D 0 } set=
 ] unit-test
@@ -126,7 +126,7 @@ IN: compiler.cfg.stack-analysis.tests
     stack-analysis
     drop
 
-    3 get instructions>> second loc>>
+    3 get successors>> first instructions>> first loc>>
 ] unit-test
 
 ! Do inserted ##peeks reference the correct stack location if
@@ -156,7 +156,7 @@ IN: compiler.cfg.stack-analysis.tests
     stack-analysis
     drop
 
-    3 get instructions>> [ ##peek? ] find nip loc>>
+    3 get successors>> first instructions>> [ ##peek? ] find nip loc>>
 ] unit-test
 
 ! Missing ##replace
@@ -170,9 +170,9 @@ IN: compiler.cfg.stack-analysis.tests
 ! Inserted ##peeks reference the wrong stack location
 [ t ] [
     [ [ "B" ] 2dip dup [ [ /mod ] dip ] when ] test-stack-analysis
-    eliminate-dead-code reverse-post-order 3 swap nth
+    eliminate-dead-code reverse-post-order 4 swap nth
     instructions>> [ ##peek? ] filter [ loc>> ] map
-    { R 0 D 0 D 1 } set=
+    { D 0 D 1 } set=
 ] unit-test
 
 [ D 0 ] [
@@ -200,5 +200,5 @@ IN: compiler.cfg.stack-analysis.tests
     stack-analysis
     drop
 
-    3 get instructions>> [ ##peek? ] find nip loc>>
+    3 get successors>> first instructions>> [ ##peek? ] find nip loc>>
 ] unit-test
\ No newline at end of file
diff --git a/basis/compiler/cfg/stack-analysis/stack-analysis.factor b/basis/compiler/cfg/stack-analysis/stack-analysis.factor
index ab16bbea44..48a4b79783 100644
--- a/basis/compiler/cfg/stack-analysis/stack-analysis.factor
+++ b/basis/compiler/cfg/stack-analysis/stack-analysis.factor
@@ -1,7 +1,7 @@
 ! 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
+sets make combinators dlists deques
 compiler.cfg
 compiler.cfg.copy-prop
 compiler.cfg.def-use
@@ -10,9 +10,14 @@ compiler.cfg.registers
 compiler.cfg.rpo
 compiler.cfg.hats
 compiler.cfg.stack-analysis.state
-compiler.cfg.stack-analysis.merge ;
+compiler.cfg.stack-analysis.merge
+compiler.cfg.utilities ;
 IN: compiler.cfg.stack-analysis
 
+SYMBOL: work-list
+
+: add-to-work-list ( bb -- ) work-list get push-front ;
+
 : redundant-replace? ( vreg loc -- ? )
     dup state get untranslate-loc n>> 0 <
     [ 2drop t ] [ state get actual-locs>vregs>> at = ] if ;
@@ -137,10 +142,21 @@ SYMBOLS: state-in state-out ;
         ] 2bi
     ] V{ } make >>instructions drop ;
 
+: visit-successors ( bb -- )
+    dup successors>> [
+        2dup back-edge? [ 2drop ] [ nip add-to-work-list ] if
+    ] with each ;
+
+: process-work-list ( -- )
+    work-list get [ visit-block ] slurp-deque ;
+
 : stack-analysis ( cfg -- cfg' )
     [
+        <hashed-dlist> work-list set
         H{ } clone copies set
         H{ } clone state-in set
         H{ } clone state-out set
-        dup [ visit-block ] each-basic-block
+        dup [ add-to-work-list ] each-basic-block
+        process-work-list
+        cfg-changed
     ] with-scope ;
diff --git a/basis/compiler/cfg/tco/tco.factor b/basis/compiler/cfg/tco/tco.factor
index df5d962999..5fa2e1b042 100644
--- a/basis/compiler/cfg/tco/tco.factor
+++ b/basis/compiler/cfg/tco/tco.factor
@@ -5,7 +5,8 @@ namespaces sequences fry combinators
 compiler.cfg
 compiler.cfg.rpo
 compiler.cfg.hats
-compiler.cfg.instructions ;
+compiler.cfg.instructions
+compiler.cfg.utilities ;
 IN: compiler.cfg.tco
 
 ! Tail call optimization. You must run compute-predecessors after this
@@ -82,4 +83,4 @@ M: ##fixnum-mul convert-fixnum-tail-call* drop i i \ ##fixnum-mul-tail new-insn
 : optimize-tail-calls ( cfg -- cfg' )
     dup cfg set
     dup [ optimize-tail-call ] each-basic-block
-    f >>post-order ;
\ No newline at end of file
+    cfg-changed ;
\ No newline at end of file
diff --git a/basis/compiler/cfg/useless-conditionals/useless-conditionals.factor b/basis/compiler/cfg/useless-conditionals/useless-conditionals.factor
index 6f4a6eea55..cc98d08042 100644
--- a/basis/compiler/cfg/useless-conditionals/useless-conditionals.factor
+++ b/basis/compiler/cfg/useless-conditionals/useless-conditionals.factor
@@ -1,7 +1,8 @@
 ! Copyright (C) 2008, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel accessors sequences math combinators combinators.short-circuit
-classes vectors compiler.cfg compiler.cfg.instructions compiler.cfg.rpo ;
+classes vectors compiler.cfg compiler.cfg.instructions compiler.cfg.rpo
+compiler.cfg.utilities ;
 IN: compiler.cfg.useless-conditionals
 
 : delete-conditional? ( bb -- ? )
@@ -18,4 +19,4 @@ IN: compiler.cfg.useless-conditionals
     dup [
         dup delete-conditional? [ delete-conditional ] [ drop ] if
     ] each-basic-block
-    f >>post-order ;
+    cfg-changed ;
diff --git a/basis/compiler/cfg/utilities/utilities.factor b/basis/compiler/cfg/utilities/utilities.factor
index 99a138a763..0e08607331 100644
--- a/basis/compiler/cfg/utilities/utilities.factor
+++ b/basis/compiler/cfg/utilities/utilities.factor
@@ -1,8 +1,8 @@
-! Copyright (C) 2008 Slava Pestov.
+! Copyright (C) 2008, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors kernel math layouts make sequences combinators
-cpu.architecture namespaces compiler.cfg
-compiler.cfg.instructions ;
+USING: accessors assocs combinators combinators.short-circuit
+compiler.cfg compiler.cfg.instructions cpu.architecture kernel
+layouts locals make math namespaces sequences sets vectors ;
 IN: compiler.cfg.utilities
 
 : value-info-small-fixnum? ( value-info -- ? )
@@ -33,7 +33,53 @@ IN: compiler.cfg.utilities
     building off
     basic-block off ;
 
-: stop-iterating ( -- next ) end-basic-block f ;
-
 : emit-primitive ( node -- )
     word>> ##call ##branch begin-basic-block ;
+
+: back-edge? ( from to -- ? )
+    [ number>> ] bi@ >= ;
+
+: empty-block? ( bb -- ? )
+    instructions>> {
+        [ length 1 = ]
+        [ first ##branch? ]
+    } 1&& ;
+
+SYMBOL: visited
+
+: (skip-empty-blocks) ( bb -- bb' )
+    dup visited get key? [
+        dup empty-block? [
+            dup visited get conjoin
+            successors>> first (skip-empty-blocks)
+        ] when
+    ] unless ;
+
+: skip-empty-blocks ( bb -- bb' )
+    H{ } clone visited [ (skip-empty-blocks) ] with-variable ;
+
+! assoc mapping predecessors to sequences
+SYMBOL: added-instructions
+
+: add-instructions ( predecessor quot -- )
+    [
+        added-instructions get
+        [ drop V{ } clone ] cache
+        building
+    ] dip with-variable ; inline
+
+:: insert-basic-block ( from to bb -- )
+    bb from 1vector >>predecessors drop
+    bb to 1vector >>successors drop
+    to predecessors>> [ dup from eq? [ drop bb ] when ] change-each
+    from successors>> [ dup to eq? [ drop bb ] when ] change-each ;
+
+:: insert-basic-blocks ( bb -- )
+    added-instructions get
+    [| predecessor instructions |
+        \ ##branch new-insn instructions push
+        predecessor bb
+        <basic-block> instructions >>instructions
+        insert-basic-block
+    ] assoc-each ;
+

From 8ff473e42cdc6b1965703938e21be27ecd51abce Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@slava-pestovs-macbook-pro.local>
Date: Sun, 12 Jul 2009 23:00:33 -0500
Subject: [PATCH 3/5] compiler.cfg.linear-scan.resolve: get it to work on CFGs
 with critical edges

---
 .../cfg/linear-scan/linear-scan-tests.factor  |  9 +++--
 .../cfg/linear-scan/linear-scan.factor        |  1 +
 .../linear-scan/resolve/resolve-tests.factor  |  7 ----
 .../cfg/linear-scan/resolve/resolve.factor    | 39 +++----------------
 basis/compiler/cfg/utilities/utilities.factor | 18 ++++-----
 5 files changed, 21 insertions(+), 53 deletions(-)
 delete mode 100644 basis/compiler/cfg/linear-scan/resolve/resolve-tests.factor

diff --git a/basis/compiler/cfg/linear-scan/linear-scan-tests.factor b/basis/compiler/cfg/linear-scan/linear-scan-tests.factor
index e8b4b67cf0..20f8570f84 100644
--- a/basis/compiler/cfg/linear-scan/linear-scan-tests.factor
+++ b/basis/compiler/cfg/linear-scan/linear-scan-tests.factor
@@ -1509,6 +1509,7 @@ SYMBOL: linear-scan-result
         compute-liveness
         dup reverse-post-order
         { { int-regs regs } } (linear-scan)
+        cfg-changed
         flatten-cfg 1array mr.
     ] with-scope ;
 
@@ -1803,7 +1804,7 @@ test-diamond
 
 [ ] [ { 1 2 } test-linear-scan-on-cfg ] unit-test
 
-[ _spill ] [ 2 get instructions>> first class ] unit-test
+[ _spill ] [ 2 get successors>> first instructions>> first class ] unit-test
 
 [ _spill ] [ 3 get instructions>> second class ] unit-test
 
@@ -1859,7 +1860,7 @@ V{
 
 [ t ] [ 2 get instructions>> [ _spill? ] any? ] unit-test
 
-[ t ] [ 3 get instructions>> [ _spill? ] any? ] unit-test
+[ t ] [ 3 get predecessors>> first instructions>> [ _spill? ] any? ] unit-test
 
 [ t ] [ 5 get instructions>> [ _reload? ] any? ] unit-test
 
@@ -1926,7 +1927,7 @@ V{
 [ V{ 3 2 1 } ] [ 9 get instructions>> [ _reload? ] filter [ n>> ] map ] unit-test
 
 ! Resolve pass should insert this
-[ _reload ] [ 5 get instructions>> first class ] unit-test
+[ _reload ] [ 5 get predecessors>> first instructions>> first class ] unit-test
 
 ! Some random bug
 V{
@@ -2484,7 +2485,7 @@ test-diamond
 
 [ 1 ] [ 2 get instructions>> [ _spill? ] count ] unit-test
 
-[ 1 ] [ 3 get instructions>> [ _spill? ] count ] unit-test
+[ 1 ] [ 3 get predecessors>> first instructions>> [ _spill? ] count ] unit-test
 
 [ 1 ] [ 4 get instructions>> [ _reload? ] count ] unit-test
 
diff --git a/basis/compiler/cfg/linear-scan/linear-scan.factor b/basis/compiler/cfg/linear-scan/linear-scan.factor
index 77d66c274d..c17aa23e83 100644
--- a/basis/compiler/cfg/linear-scan/linear-scan.factor
+++ b/basis/compiler/cfg/linear-scan/linear-scan.factor
@@ -40,4 +40,5 @@ IN: compiler.cfg.linear-scan
         init-mapping
         dup reverse-post-order machine-registers (linear-scan)
         spill-counts get >>spill-counts
+        cfg-changed
     ] with-scope ;
diff --git a/basis/compiler/cfg/linear-scan/resolve/resolve-tests.factor b/basis/compiler/cfg/linear-scan/resolve/resolve-tests.factor
deleted file mode 100644
index b5e95258bf..0000000000
--- a/basis/compiler/cfg/linear-scan/resolve/resolve-tests.factor
+++ /dev/null
@@ -1,7 +0,0 @@
-USING: arrays compiler.cfg.linear-scan.resolve kernel
-tools.test ;
-IN: compiler.cfg.linear-scan.resolve.tests
-
-[ { 1 2 3 4 5 6 } ] [
-    { 3 4 } V{ 1 2 } clone [ { 5 6 } 3append-here ] keep >array
-] unit-test
diff --git a/basis/compiler/cfg/linear-scan/resolve/resolve.factor b/basis/compiler/cfg/linear-scan/resolve/resolve.factor
index 7b7f242e4e..f7ed994f18 100644
--- a/basis/compiler/cfg/linear-scan/resolve/resolve.factor
+++ b/basis/compiler/cfg/linear-scan/resolve/resolve.factor
@@ -3,6 +3,7 @@
 USING: accessors arrays assocs combinators
 combinators.short-circuit fry kernel locals
 make math sequences
+compiler.cfg.utilities
 compiler.cfg.instructions
 compiler.cfg.linear-scan.assignment
 compiler.cfg.linear-scan.mapping compiler.cfg.liveness ;
@@ -30,42 +31,14 @@ IN: compiler.cfg.linear-scan.resolve
         [ resolve-value-data-flow ] with with each
     ] { } make ;
 
-: fork? ( from to -- ? )
-    {
-        [ drop successors>> length 1 >= ]
-        [ nip predecessors>> length 1 = ]
-    } 2&& ; inline
-
-: insert-position/fork ( from to -- before after )
-    nip instructions>> [ >array ] [ dup delete-all ] bi swap ;
-
-: join? ( from to -- ? )
-    {
-        [ drop successors>> length 1 = ]
-        [ nip predecessors>> length 1 >= ]
-    } 2&& ; inline
-
-: insert-position/join ( from to -- before after )
-    drop instructions>> dup pop 1array ;
-
-: insert-position ( bb to -- before after )
-    {
-        { [ 2dup fork? ] [ insert-position/fork ] }
-        { [ 2dup join? ] [ insert-position/join ] }
-    } cond ;
-
-: 3append-here ( seq2 seq1 seq3 -- )
-    #! Mutate seq1
-    swap '[ _ push-all ] bi@ ;
-
-: perform-mappings ( mappings bb to -- )
-    pick empty? [ 3drop ] [
-        [ mapping-instructions ] 2dip
-        insert-position 3append-here
+: perform-mappings ( bb to mappings -- )
+    dup empty? [ 3drop ] [
+        mapping-instructions <simple-block>
+        insert-basic-block
     ] if ;
 
 : resolve-edge-data-flow ( bb to -- )
-    [ compute-mappings ] [ perform-mappings ] 2bi ;
+    2dup compute-mappings perform-mappings ;
 
 : resolve-block-data-flow ( bb -- )
     dup successors>> [ resolve-edge-data-flow ] with each ;
diff --git a/basis/compiler/cfg/utilities/utilities.factor b/basis/compiler/cfg/utilities/utilities.factor
index 0e08607331..288fa403dd 100644
--- a/basis/compiler/cfg/utilities/utilities.factor
+++ b/basis/compiler/cfg/utilities/utilities.factor
@@ -2,7 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors assocs combinators combinators.short-circuit
 compiler.cfg compiler.cfg.instructions cpu.architecture kernel
-layouts locals make math namespaces sequences sets vectors ;
+layouts locals make math namespaces sequences sets vectors fry ;
 IN: compiler.cfg.utilities
 
 : value-info-small-fixnum? ( value-info -- ? )
@@ -74,12 +74,12 @@ SYMBOL: added-instructions
     to predecessors>> [ dup from eq? [ drop bb ] when ] change-each
     from successors>> [ dup to eq? [ drop bb ] when ] change-each ;
 
-:: insert-basic-blocks ( bb -- )
-    added-instructions get
-    [| predecessor instructions |
-        \ ##branch new-insn instructions push
-        predecessor bb
-        <basic-block> instructions >>instructions
-        insert-basic-block
-    ] assoc-each ;
+: <simple-block> ( insns -- bb )
+    <basic-block>
+    swap >vector
+    \ ##branch new-insn over push
+    >>instructions ;
 
+: insert-basic-blocks ( bb -- )
+    [ added-instructions get ] dip
+    '[ [ _ ] dip <simple-block> insert-basic-block ] assoc-each ;

From d7aeae45be8984bd2dc0c198758d3c9713c98dda Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@slava-pestovs-macbook-pro.local>
Date: Mon, 13 Jul 2009 10:44:08 -0500
Subject: [PATCH 4/5] compiler.cfg.branch-splitting: split blocks with
 successors

---
 .../branch-splitting-tests.factor             | 85 +++++++++++++++++++
 .../branch-splitting/branch-splitting.factor  | 82 +++++++++++++-----
 .../cfg/optimizer/optimizer-tests.factor      |  6 +-
 basis/compiler/cfg/optimizer/optimizer.factor |  3 +-
 basis/compiler/cfg/renaming/renaming.factor   |  6 ++
 .../stack-analysis/merge/merge-tests.factor   |  6 +-
 6 files changed, 162 insertions(+), 26 deletions(-)
 create mode 100644 basis/compiler/cfg/branch-splitting/branch-splitting-tests.factor

diff --git a/basis/compiler/cfg/branch-splitting/branch-splitting-tests.factor b/basis/compiler/cfg/branch-splitting/branch-splitting-tests.factor
new file mode 100644
index 0000000000..fbaaf92203
--- /dev/null
+++ b/basis/compiler/cfg/branch-splitting/branch-splitting-tests.factor
@@ -0,0 +1,85 @@
+USING: accessors assocs compiler.cfg
+compiler.cfg.branch-splitting compiler.cfg.debugger
+compiler.cfg.predecessors compiler.cfg.rpo fry kernel
+tools.test namespaces sequences vectors ;
+IN: compiler.cfg.branch-splitting.tests
+
+: get-predecessors ( cfg -- assoc )
+    H{ } clone [ '[ [ predecessors>> ] keep _ set-at ] each-basic-block ] keep ;
+
+: check-predecessors ( cfg -- )
+    [ get-predecessors ]
+    [ compute-predecessors drop ]
+    [ get-predecessors ] tri assert= ;
+
+: check-branch-splitting ( cfg -- )
+    compute-predecessors
+    split-branches
+    check-predecessors ;
+
+: test-branch-splitting ( -- )
+    cfg new 0 get >>entry check-branch-splitting ;
+
+V{ } 0 test-bb
+
+V{ } 1 test-bb
+
+V{ } 2 test-bb
+
+V{ } 3 test-bb
+
+V{ } 4 test-bb
+
+test-diamond
+
+[ ] [ test-branch-splitting ] unit-test
+
+V{ } 0 test-bb
+
+V{ } 1 test-bb
+
+V{ } 2 test-bb
+
+V{ } 3 test-bb
+
+V{ } 4 test-bb
+
+V{ } 5 test-bb
+
+0 get 1 get 2 get V{ } 2sequence >>successors drop
+
+1 get 3 get 4 get V{ } 2sequence >>successors drop
+
+2 get 3 get 4 get V{ } 2sequence >>successors drop
+
+[ ] [ test-branch-splitting ] unit-test
+
+V{ } 0 test-bb
+
+V{ } 1 test-bb
+
+V{ } 2 test-bb
+
+V{ } 3 test-bb
+
+V{ } 4 test-bb
+
+0 get 1 get 2 get V{ } 2sequence >>successors drop
+
+1 get 3 get 4 get V{ } 2sequence >>successors drop
+
+2 get 4 get 1vector >>successors drop
+
+[ ] [ test-branch-splitting ] unit-test
+
+V{ } 0 test-bb
+
+V{ } 1 test-bb
+
+V{ } 2 test-bb
+
+0 get 1 get 2 get V{ } 2sequence >>successors drop
+
+1 get 2 get 1vector >>successors drop
+
+[ ] [ test-branch-splitting ] unit-test
\ No newline at end of file
diff --git a/basis/compiler/cfg/branch-splitting/branch-splitting.factor b/basis/compiler/cfg/branch-splitting/branch-splitting.factor
index f7e9ea9cbf..0dd963125f 100644
--- a/basis/compiler/cfg/branch-splitting/branch-splitting.factor
+++ b/basis/compiler/cfg/branch-splitting/branch-splitting.factor
@@ -1,37 +1,79 @@
 ! Copyright (C) 2009 Doug Coleman, Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors combinators.short-circuit kernel math sequences
-compiler.cfg.def-use compiler.cfg compiler.cfg.rpo ;
+USING: accessors combinators.short-circuit kernel math math.order
+sequences assocs namespaces vectors fry arrays splitting
+compiler.cfg.def-use compiler.cfg compiler.cfg.rpo
+compiler.cfg.renaming compiler.cfg.instructions compiler.cfg.utilities ;
 IN: compiler.cfg.branch-splitting
 
-! Predecessors must be recomputed after this
+: clone-renamings ( insns -- assoc )
+    [ defs-vregs ] map concat [ dup fresh-vreg ] H{ } map>assoc ;
 
-: split-branch-for ( bb predecessor -- )
-    [
+: clone-instructions ( insns -- insns' )
+    dup clone-renamings renamings [
         [
-            <basic-block>
-                swap
-                [ instructions>> [ clone ] map >>instructions ]
-                [ successors>> clone >>successors ]
-                bi
-        ] keep
-    ] dip
-    [ [ 2dup eq? [ 2drop ] [ 2nip ] if ] with with map ] change-successors
-    drop ;
+            clone
+            dup rename-insn-defs
+            dup rename-insn-uses
+            dup fresh-insn-temps
+        ] map
+    ] with-variable ;
+
+: clone-basic-block ( bb -- bb' )
+    ! The new block gets the same RPO number as the old one.
+    ! This is just to make 'back-edge?' work.
+    <basic-block>
+        swap
+        [ instructions>> clone-instructions >>instructions ]
+        [ successors>> clone >>successors ]
+        [ number>> >>number ]
+        tri ;
+
+: new-blocks ( bb -- copies )
+    dup predecessors>> [
+        [ clone-basic-block ] dip
+        1vector >>predecessors
+    ] with map ;
+
+: update-predecessor-successor ( pred copy old-bb -- )
+    '[
+        [ _ _ 3dup nip eq? [ drop nip ] [ 2drop ] if ] map
+    ] change-successors drop ;
+
+: update-predecessor-successors ( copies old-bb -- )
+    [ predecessors>> swap ] keep
+    '[ _ update-predecessor-successor ] 2each ;
+
+: update-successor-predecessor ( copies old-bb succ -- )
+    [
+        swap 1array split swap join V{ } like
+    ] change-predecessors drop ;
+
+: update-successor-predecessors ( copies old-bb -- )
+    dup successors>> [
+        update-successor-predecessor
+    ] with with each ;
 
 : split-branch ( bb -- )
-    dup predecessors>> [ split-branch-for ] with each ;
+    [ new-blocks ] keep
+    [ update-predecessor-successors ]
+    [ update-successor-predecessors ]
+    2bi ;
+
+UNION: irrelevant ##peek ##replace ##inc-d ##inc-r ;
+
+: split-instructions? ( insns -- ? )
+    [ irrelevant? not ] count 5 <= ;
 
 : split-branches? ( bb -- ? )
     {
-        [ successors>> empty? ]
-        [ predecessors>> length 1 > ]
-        [ instructions>> [ defs-vregs ] any? not ]
-        [ instructions>> [ temp-vregs ] any? not ]
+        [ dup successors>> [ back-edge? ] with any? not ]
+        [ predecessors>> length 1 4 between? ]
+        [ instructions>> split-instructions? ]
     } 1&& ;
 
 : split-branches ( cfg -- cfg' )
     dup [
         dup split-branches? [ split-branch ] [ drop ] if
     ] each-basic-block
-    f >>post-order ;
+    cfg-changed ;
diff --git a/basis/compiler/cfg/optimizer/optimizer-tests.factor b/basis/compiler/cfg/optimizer/optimizer-tests.factor
index f585d80d72..1eb1996da4 100755
--- a/basis/compiler/cfg/optimizer/optimizer-tests.factor
+++ b/basis/compiler/cfg/optimizer/optimizer-tests.factor
@@ -2,7 +2,7 @@ USING: accessors arrays compiler.cfg.checker
 compiler.cfg.debugger compiler.cfg.def-use
 compiler.cfg.instructions fry kernel kernel.private math
 math.partial-dispatch math.private sbufs sequences sequences.private sets
-slots.private strings tools.test vectors layouts ;
+slots.private strings strings.private tools.test vectors layouts ;
 IN: compiler.cfg.optimizer.tests
 
 ! Miscellaneous tests
@@ -40,6 +40,10 @@ IN: compiler.cfg.optimizer.tests
             ] [ 2drop f ] if
         ] [ 2drop f ] if
     ]
+    [
+        pick 10 fixnum>= [ [ 123 fixnum-bitand ] 2dip ] [ ] if
+        set-string-nth-fast
+    ]
 } [
     [ [ ] ] dip '[ _ test-mr first check-mr ] unit-test
 ] each
diff --git a/basis/compiler/cfg/optimizer/optimizer.factor b/basis/compiler/cfg/optimizer/optimizer.factor
index 84eb8a84d1..5b0892a0ee 100644
--- a/basis/compiler/cfg/optimizer/optimizer.factor
+++ b/basis/compiler/cfg/optimizer/optimizer.factor
@@ -29,10 +29,9 @@ SYMBOL: check-optimizer?
     ! The passes that need this document it.
     [
         optimize-tail-calls
-        compute-predecessors
         delete-useless-conditionals
-        split-branches
         compute-predecessors
+        split-branches
         stack-analysis
         compute-liveness
         alias-analysis
diff --git a/basis/compiler/cfg/renaming/renaming.factor b/basis/compiler/cfg/renaming/renaming.factor
index 4a8c6e6a4d..228d72483c 100644
--- a/basis/compiler/cfg/renaming/renaming.factor
+++ b/basis/compiler/cfg/renaming/renaming.factor
@@ -55,6 +55,12 @@ M: ##string-nth rename-insn-uses
     [ rename-value ] change-index
     drop ;
 
+M: ##set-string-nth-fast rename-insn-uses
+    dup call-next-method
+    [ rename-value ] change-obj
+    [ rename-value ] change-index
+    drop ;
+
 M: ##set-slot-imm rename-insn-uses
     dup call-next-method
     [ rename-value ] change-obj
diff --git a/basis/compiler/cfg/stack-analysis/merge/merge-tests.factor b/basis/compiler/cfg/stack-analysis/merge/merge-tests.factor
index e67f6b5143..5883777861 100644
--- a/basis/compiler/cfg/stack-analysis/merge/merge-tests.factor
+++ b/basis/compiler/cfg/stack-analysis/merge/merge-tests.factor
@@ -1,8 +1,8 @@
 IN: compiler.cfg.stack-analysis.merge.tests
 USING: compiler.cfg.stack-analysis.merge tools.test arrays accessors
-compiler.cfg.instructions compiler.cfg.stack-analysis.state
-compiler.cfg compiler.cfg.registers compiler.cfg.debugger
-cpu.architecture make assocs namespaces
+ compiler.cfg.instructions compiler.cfg.stack-analysis.state
+compiler.cfg.utilities compiler.cfg compiler.cfg.registers
+compiler.cfg.debugger cpu.architecture make assocs namespaces
 sequences kernel classes ;
 
 [

From 3b244d5d4149a88516482aa2f6a784468259e655 Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@slava-pestovs-macbook-pro.local>
Date: Mon, 13 Jul 2009 12:33:58 -0500
Subject: [PATCH 5/5] compiler.cfg.value-numbering: fix ##compare and
 ##compare-branch rewrites

---
 .../value-numbering/rewrite/rewrite.factor    | 39 ++++++++++---------
 core/sequences/sequences-tests.factor         |  5 ++-
 2 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/basis/compiler/cfg/value-numbering/rewrite/rewrite.factor b/basis/compiler/cfg/value-numbering/rewrite/rewrite.factor
index ca7a959a82..92965e40c5 100755
--- a/basis/compiler/cfg/value-numbering/rewrite/rewrite.factor
+++ b/basis/compiler/cfg/value-numbering/rewrite/rewrite.factor
@@ -77,13 +77,19 @@ M: ##compare-imm-branch rewrite
     insn cc>> swap? [ swap-cc ] when
     i \ ##compare-imm new-insn ; inline
 
-! M: ##compare rewrite
-!     dup [ src1>> ] [ src2>> ] bi
-!     [ vreg>expr constant-expr? ] bi@ 2array {
-!         { { f t } [ f >compare-imm ] }
-!         { { t f } [ t >compare-imm ] }
-!         [ drop ]
-!     } case ;
+: vreg-small-constant? ( vreg -- ? )
+    vreg>expr {
+        [ constant-expr? ]
+        [ value>> small-enough? ]
+    } 1&& ;
+
+M: ##compare rewrite
+    dup [ src1>> ] [ src2>> ] bi
+    [ vreg-small-constant? ] bi@ 2array {
+        { { f t } [ f >compare-imm ] }
+        { { t f } [ t >compare-imm ] }
+        [ drop ]
+    } case ;
 
 :: >compare-imm-branch ( insn swap? -- insn' )
     insn src1>>
@@ -91,13 +97,13 @@ M: ##compare-imm-branch rewrite
     insn cc>> swap? [ swap-cc ] when
     \ ##compare-imm-branch new-insn ; inline
 
-! M: ##compare-branch rewrite
-!     dup [ src1>> ] [ src2>> ] bi
-!     [ vreg>expr constant-expr? ] bi@ 2array {
-!         { { f t } [ f >compare-imm-branch ] }
-!         { { t f } [ t >compare-imm-branch ] }
-!         [ drop ]
-!     } case ;
+M: ##compare-branch rewrite
+    dup [ src1>> ] [ src2>> ] bi
+    [ vreg-small-constant? ] bi@ 2array {
+        { { f t } [ f >compare-imm-branch ] }
+        { { t f } [ t >compare-imm-branch ] }
+        [ drop ]
+    } case ;
 
 : rewrite-redundant-comparison? ( insn -- ? )
     {
@@ -198,10 +204,7 @@ M: ##or-imm rewrite [ bitor ] \ ##or-imm combine-imm ;
 M: ##xor-imm rewrite [ bitxor ] \ ##xor-imm combine-imm ;
 
 : rewrite-add? ( insn -- ? )
-    src2>> {
-        [ vreg>expr constant-expr? ]
-        [ vreg>constant small-enough? ]
-    } 1&& ;
+    src2>> vreg-small-constant? ;
 
 M: ##add rewrite
     dup rewrite-add? [
diff --git a/core/sequences/sequences-tests.factor b/core/sequences/sequences-tests.factor
index 5e0d5597ca..2aa95b23ab 100644
--- a/core/sequences/sequences-tests.factor
+++ b/core/sequences/sequences-tests.factor
@@ -290,4 +290,7 @@ M: bogus-hashcode hashcode* 2drop 0 >bignum ;
 USE: make
 
 [ { "a" 1 "b" 1 "c" } ]
-[ 1 { "a" "b" "c" } [ [ dup , ] [ , ] interleave drop ] { } make ] unit-test
\ No newline at end of file
+[ 1 { "a" "b" "c" } [ [ dup , ] [ , ] interleave drop ] { } make ] unit-test
+
+[ t ] [ 0 array-capacity? ] unit-test
+[ f ] [ -1 array-capacity? ] unit-test
\ No newline at end of file