diff --git a/basis/compiler/cfg/alias-analysis/alias-analysis.factor b/basis/compiler/cfg/alias-analysis/alias-analysis.factor
index dcd38277c7..96945dfad0 100644
--- a/basis/compiler/cfg/alias-analysis/alias-analysis.factor
+++ b/basis/compiler/cfg/alias-analysis/alias-analysis.factor
@@ -325,6 +325,6 @@ M: insn eliminate-dead-stores drop t ;
     [ 0 [ [ insn#<< ] [ drop 1 + ] 2bi ] reduce drop ]
     [ [ analyze-aliases ] map! [ eliminate-dead-stores ] filter! ] bi ;
 
-: alias-analysis ( cfg -- cfg )
+: alias-analysis ( cfg -- )
     init-alias-analysis
-    dup [ alias-analysis-step ] simple-optimization ;
+    [ alias-analysis-step ] simple-optimization ;
diff --git a/basis/compiler/cfg/block-joining/block-joining.factor b/basis/compiler/cfg/block-joining/block-joining.factor
index 54cff306ed..93f48b52bb 100644
--- a/basis/compiler/cfg/block-joining/block-joining.factor
+++ b/basis/compiler/cfg/block-joining/block-joining.factor
@@ -26,7 +26,7 @@ IN: compiler.cfg.block-joining
 : join-block ( bb pred -- )
     [ join-instructions ] [ update-successors ] 2bi ;
 
-: join-blocks ( cfg -- cfg' )
+: join-blocks ( cfg -- )
     needs-predecessors
 
     dup post-order [
@@ -34,4 +34,4 @@ IN: compiler.cfg.block-joining
         [ dup predecessor join-block ] [ drop ] if
     ] each
 
-    cfg-changed predecessors-changed ;
+    cfg-changed predecessors-changed drop ;
diff --git a/basis/compiler/cfg/branch-splitting/branch-splitting.factor b/basis/compiler/cfg/branch-splitting/branch-splitting.factor
index 157fd355cd..fd9eea23df 100644
--- a/basis/compiler/cfg/branch-splitting/branch-splitting.factor
+++ b/basis/compiler/cfg/branch-splitting/branch-splitting.factor
@@ -93,7 +93,7 @@ SYMBOL: visited
     HS{ } clone visited set
     entry>> add-to-worklist ;
 
-: split-branches ( cfg -- cfg' )
+: split-branches ( cfg -- )
     needs-predecessors
     dup init-worklist
     ! For back-edge?
@@ -104,4 +104,4 @@ SYMBOL: visited
         successors>> [ add-to-worklist ] each
     ] slurp-deque
 
-    cfg-changed ;
+    cfg-changed drop ;
diff --git a/basis/compiler/cfg/copy-prop/copy-prop.factor b/basis/compiler/cfg/copy-prop/copy-prop.factor
index 64f0f26f3e..c0024f0752 100644
--- a/basis/compiler/cfg/copy-prop/copy-prop.factor
+++ b/basis/compiler/cfg/copy-prop/copy-prop.factor
@@ -119,10 +119,8 @@ PRIVATE>
 
 USE: compiler.cfg
 
-: copy-propagation ( cfg -- cfg' )
+: copy-propagation ( cfg -- )
     needs-predecessors
-
     dup collect-copies
     dup rename-copies
-
-    predecessors-changed ;
+    predecessors-changed drop ;
diff --git a/basis/compiler/cfg/dce/dce.factor b/basis/compiler/cfg/dce/dce.factor
index 28c75ec18a..456cb07827 100644
--- a/basis/compiler/cfg/dce/dce.factor
+++ b/basis/compiler/cfg/dce/dce.factor
@@ -115,14 +115,13 @@ M: flushable-insn live-insn? defs-vregs [ live-vreg? ] any? ;
 
 M: insn live-insn? drop t ;
 
-: eliminate-dead-code ( cfg -- cfg' )
+: eliminate-dead-code ( cfg -- )
     ! Even though we don't use predecessors directly, we depend
     ! on the predecessors pass updating phi nodes to remove dead
     ! inputs.
     needs-predecessors
 
     init-dead-code
-    dup
     [ [ [ build-liveness-graph ] each ] simple-analysis ]
     [ [ [ compute-live-vregs ] each ] simple-analysis ]
     [ [ [ live-insn? ] filter! ] simple-optimization ]
diff --git a/basis/compiler/cfg/height/height.factor b/basis/compiler/cfg/height/height.factor
index f8f360f007..1609e609ca 100644
--- a/basis/compiler/cfg/height/height.factor
+++ b/basis/compiler/cfg/height/height.factor
@@ -51,5 +51,5 @@ M: insn visit-insn drop ;
         rs-height get [ ##inc-r new-insn prefix ] unless-zero
     ] bi ;
 
-: normalize-height ( cfg -- cfg' )
-    dup [ height-step ] simple-optimization ;
+: normalize-height ( cfg -- )
+    [ height-step ] simple-optimization ;
diff --git a/basis/compiler/cfg/optimizer/optimizer.factor b/basis/compiler/cfg/optimizer/optimizer.factor
index 6a62b6f7e7..7138999772 100644
--- a/basis/compiler/cfg/optimizer/optimizer.factor
+++ b/basis/compiler/cfg/optimizer/optimizer.factor
@@ -9,17 +9,20 @@ compiler.cfg.ssa.construction
 compiler.cfg.alias-analysis
 compiler.cfg.value-numbering
 compiler.cfg.copy-prop
-compiler.cfg.dce ;
+compiler.cfg.dce
+kernel sequences ;
 IN: compiler.cfg.optimizer
 
 : optimize-cfg ( cfg -- cfg' )
-    optimize-tail-calls
-    delete-useless-conditionals
-    split-branches
-    join-blocks
-    normalize-height
-    construct-ssa
-    alias-analysis
-    value-numbering
-    copy-propagation
-    eliminate-dead-code ;
+    dup {
+        optimize-tail-calls
+        delete-useless-conditionals
+        split-branches
+        join-blocks
+        normalize-height
+        construct-ssa
+        alias-analysis
+        value-numbering
+        copy-propagation
+        eliminate-dead-code
+    } [ execute( x -- ) ] with each ;
diff --git a/basis/compiler/cfg/ssa/construction/construction.factor b/basis/compiler/cfg/ssa/construction/construction.factor
index bec0971e03..111cc7fc0d 100644
--- a/basis/compiler/cfg/ssa/construction/construction.factor
+++ b/basis/compiler/cfg/ssa/construction/construction.factor
@@ -182,10 +182,7 @@ SYMBOL: live-phis
 
 PRIVATE>
 
-: construct-ssa ( cfg -- cfg' )
-    {
-        [ compute-merge-sets ]
-        [ compute-defs compute-phis ]
-        [ rename compute-live-phis insert-phis ]
-        [ ]
-    } cleave ;
+: construct-ssa ( cfg -- )
+    [ compute-merge-sets ]
+    [ compute-defs compute-phis ]
+    [ rename compute-live-phis insert-phis ] tri ;
diff --git a/basis/compiler/cfg/tco/tco.factor b/basis/compiler/cfg/tco/tco.factor
index 2effc432ac..06bdab7889 100644
--- a/basis/compiler/cfg/tco/tco.factor
+++ b/basis/compiler/cfg/tco/tco.factor
@@ -71,7 +71,7 @@ IN: compiler.cfg.tco
         } cond
     ] [ drop ] if ;
 
-: optimize-tail-calls ( cfg -- cfg' )
+: optimize-tail-calls ( cfg -- )
     dup [ optimize-tail-call ] each-basic-block
 
-    cfg-changed predecessors-changed ;
+    cfg-changed predecessors-changed drop ;
diff --git a/basis/compiler/cfg/useless-conditionals/useless-conditionals.factor b/basis/compiler/cfg/useless-conditionals/useless-conditionals.factor
index cf7a490c9f..126f4892dd 100644
--- a/basis/compiler/cfg/useless-conditionals/useless-conditionals.factor
+++ b/basis/compiler/cfg/useless-conditionals/useless-conditionals.factor
@@ -25,9 +25,9 @@ IN: compiler.cfg.useless-conditionals
     [ first skip-empty-blocks 1vector ] change-successors
     instructions>> [ pop* ] [ [ ##branch new-insn ] dip push ] bi ;
 
-: delete-useless-conditionals ( cfg -- cfg' )
+: delete-useless-conditionals ( cfg -- )
     dup [
         dup delete-conditional? [ delete-conditional ] [ drop ] if
     ] each-basic-block
-    
-    cfg-changed predecessors-changed ;
+
+    cfg-changed predecessors-changed drop ;
diff --git a/basis/compiler/cfg/value-numbering/value-numbering.factor b/basis/compiler/cfg/value-numbering/value-numbering.factor
index 2418a67eae..38296c5601 100644
--- a/basis/compiler/cfg/value-numbering/value-numbering.factor
+++ b/basis/compiler/cfg/value-numbering/value-numbering.factor
@@ -1,9 +1,6 @@
 ! Copyright (C) 2008, 2010 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: namespaces arrays assocs kernel accessors
-sorting sets sequences locals
-cpu.architecture
-sequences.deep
+USING: accessors arrays assocs
 compiler.cfg
 compiler.cfg.rpo
 compiler.cfg.def-use
@@ -16,7 +13,9 @@ compiler.cfg.value-numbering.math
 compiler.cfg.value-numbering.rewrite
 compiler.cfg.value-numbering.slots
 compiler.cfg.value-numbering.misc
-compiler.cfg.value-numbering.expressions ;
+compiler.cfg.value-numbering.expressions
+cpu.architecture kernel locals namespaces sequences sequences.deep sets
+sorting ;
 IN: compiler.cfg.value-numbering
 
 GENERIC: process-instruction ( insn -- insn' )
@@ -53,7 +52,6 @@ M: array process-instruction
     init-value-graph
     [ process-instruction ] map flatten ;
 
-: value-numbering ( cfg -- cfg )
+: value-numbering ( cfg -- )
     dup [ value-numbering-step ] simple-optimization
-
-    cfg-changed predecessors-changed ;
+    cfg-changed predecessors-changed drop ;