diff --git a/basis/compiler/cfg/builder/blocks/blocks.factor b/basis/compiler/cfg/builder/blocks/blocks.factor
index 752fce6534..0dbcf68496 100644
--- a/basis/compiler/cfg/builder/blocks/blocks.factor
+++ b/basis/compiler/cfg/builder/blocks/blocks.factor
@@ -8,8 +8,9 @@ SLOT: out-d
 IN: compiler.cfg.builder.blocks
 
 : set-basic-block ( basic-block -- )
-    [ basic-block set ] [ instructions>> building set ] bi
-    begin-local-analysis ;
+    [ basic-block set ]
+    [ instructions>> building set ]
+    [ begin-local-analysis ] tri ;
 
 : end-basic-block ( -- )
     basic-block get [ end-local-analysis ] when*
diff --git a/basis/compiler/cfg/builder/builder-tests.factor b/basis/compiler/cfg/builder/builder-tests.factor
index d189dab124..ac91bfe987 100644
--- a/basis/compiler/cfg/builder/builder-tests.factor
+++ b/basis/compiler/cfg/builder/builder-tests.factor
@@ -265,7 +265,7 @@ IN: compiler.cfg.builder.tests
        { out-d V{ 2 3 } }
     } emit-node
     height-state get
-    replace-mapping get
+    replaces get
 ] cfg-unit-test
 
 { 1 } [
@@ -293,7 +293,7 @@ SYMBOL: foo
     H{ { D 2 1 } }
 } [
     T{ #shuffle { in-d { 7 3 0 } } { out-d { 55 } } { mapping { { 55 3 } } } }
-    emit-node replace-mapping get
+    emit-node replaces get
 ] cfg-unit-test
 
 {
@@ -303,5 +303,5 @@ SYMBOL: foo
        { in-d { 7 } }
        { out-d { 55 77 } }
        { mapping { { 55 7 } { 77 7 } } }
-    } emit-node replace-mapping get
+    } emit-node replaces get
 ] cfg-unit-test
diff --git a/basis/compiler/cfg/intrinsics/fixnum/fixnum.factor b/basis/compiler/cfg/intrinsics/fixnum/fixnum.factor
index a83502810e..397e2ace25 100644
--- a/basis/compiler/cfg/intrinsics/fixnum/fixnum.factor
+++ b/basis/compiler/cfg/intrinsics/fixnum/fixnum.factor
@@ -2,8 +2,8 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors arrays combinators compiler.cfg.builder.blocks
 compiler.cfg.comparisons compiler.cfg.hats
-compiler.cfg.instructions compiler.cfg.stacks
-compiler.tree.propagation.info cpu.architecture fry kernel
+compiler.cfg.instructions compiler.cfg.stacks.local compiler.cfg.registers
+compiler.cfg.stacks compiler.tree.propagation.info cpu.architecture fry kernel
 layouts math math.intervals namespaces sequences ;
 IN: compiler.cfg.intrinsics.fixnum
 
@@ -41,7 +41,7 @@ IN: compiler.cfg.intrinsics.fixnum
     '[ _ ^^compare-integer ] binary-op ;
 
 : emit-no-overflow-case ( dst -- final-bb )
-    [ ds-drop ds-drop ds-push ] with-branch ;
+    [ D -2 inc-stack ds-push ] with-branch ;
 
 : emit-overflow-case ( word -- final-bb )
     [
diff --git a/basis/compiler/cfg/stacks/local/local-docs.factor b/basis/compiler/cfg/stacks/local/local-docs.factor
index e8d6903d7a..cd3f65f23e 100644
--- a/basis/compiler/cfg/stacks/local/local-docs.factor
+++ b/basis/compiler/cfg/stacks/local/local-docs.factor
@@ -2,7 +2,7 @@ USING: assocs compiler.cfg compiler.cfg.instructions compiler.cfg.registers
 help.markup help.syntax math sequences ;
 IN: compiler.cfg.stacks.local
 
-HELP: replace-mapping
+HELP: replaces
 { $var-description "An " { $link assoc } " that maps from stack locations to virtual registers that were put on the stack." }
 { $see-also replace-loc } ;
 
@@ -15,14 +15,15 @@ HELP: loc>vreg
 
 HELP: replace-loc
 { $values { "vreg" "virtual register" } { "loc" loc } }
-{ $description "Registers that the absolute stack location " { $snippet "loc" } " should be overwritten with the contents of the virtual register." } ;
+{ $description "Registers that the absolute stack location " { $snippet "loc" } " should be overwritten with the contents of the virtual register." }
+{ $see-also replaces } ;
 
 HELP: peek-loc
 { $values { "loc" loc } { "vreg" "virtaul register" } }
 { $description "Retrieves the virtual register at the given stack location." } ;
 
 HELP: translate-local-loc
-{ $values { "state" "height state" } { "loc" loc } { "loc'" loc } }
+{ $values { "loc" loc } { "state" "height state" }  { "loc'" loc } }
 { $description "Translates an absolute stack location to one that is relative to the given height state." }
 { $examples
   { $example
diff --git a/basis/compiler/cfg/stacks/local/local-tests.factor b/basis/compiler/cfg/stacks/local/local-tests.factor
index a330ff14de..c85f98110a 100644
--- a/basis/compiler/cfg/stacks/local/local-tests.factor
+++ b/basis/compiler/cfg/stacks/local/local-tests.factor
@@ -17,7 +17,7 @@ IN: compiler.cfg.stacks.local.tests
         T{ ##copy { dst 2 } { src 26 } { rep any-rep } }
     }
 } [
-    { { D 0 25 } { R 0 26 } } stack-changes
+    { { D 0 25 } { R 0 26 } } replaces>copy-insns
 ] cfg-unit-test
 
 ! replace-loc
@@ -32,16 +32,20 @@ IN: compiler.cfg.stacks.local.tests
     { }
     HS{ }
 } [
-    "foo" [ "eh" , end-local-analysis ] V{ } make drop
-    "foo" [ peek-sets ] [ replace-sets ] [ kill-sets ] tri [ get at ] 2tri@
+    V{ } 137 insns>block
+    [ 0 0 rot record-stack-heights ]
+    [ [ "eh" , end-local-analysis ] V{ } make drop ]
+    [ [ peek-sets ] [ replace-sets ] [ kill-sets ] tri [ get at ] 2tri@ ] tri
 ] cfg-unit-test
 
 {
     { D 3 }
 } [
-    "foo" [ 3 D 3 replace-loc "eh" , end-local-analysis ] V{ } make drop
-    replace-sets get "foo" of
-] unit-test
+    V{ } 137 insns>block
+    [ 0 0 rot record-stack-heights ]
+    [ [ 3 D 3 replace-loc "eh" , end-local-analysis ] V{ } make drop ]
+    [ replace-sets get at ] tri
+] cfg-unit-test
 
 ! remove-redundant-replaces
 {
@@ -49,7 +53,7 @@ IN: compiler.cfg.stacks.local.tests
 } [
     D 0 loc>vreg D 2 loc>vreg 2drop
     2 D 2 replace-loc 7 D 3 replace-loc
-    replace-mapping get remove-redundant-replaces
+    replaces get remove-redundant-replaces
 ] cfg-unit-test
 
 ! emit-changes
@@ -58,10 +62,14 @@ IN: compiler.cfg.stacks.local.tests
 } [
     3 D 0 replace-loc [
         "eh",
-        replace-mapping get height-state get emit-changes
+        replaces get height-state get emit-changes
     ] V{ } make
 ] cfg-unit-test
 
+{ D 2 } [
+    D 3 { { 1 2 } { 3 4 } } translate-local-loc
+] unit-test
+
 ! height-state
 {
     { { 3 3 } { 0 0 } }
@@ -83,22 +91,16 @@ IN: compiler.cfg.stacks.local.tests
 ] unit-test
 
 { H{ { D -1 40 } } } [
-    D 1 inc-stack 40 D 0 replace-loc replace-mapping get
+    D 1 inc-stack 40 D 0 replace-loc replaces get
 ] cfg-unit-test
 
 { 0 } [
-    V{ } 0 insns>block basic-block set
-    init-cfg-test
+    V{ } 0 insns>block 0 0 pick record-stack-heights
     compute-local-kill-set sets:cardinality
 ] unit-test
 
 { HS{ R -4 } } [
-    H{ { 77 4 } } [ ds-heights set ] [ rs-heights set ] bi
+    V{ } 0 insns>block 4 4 pick record-stack-heights
     { { 8 0 } { 3 0 } } height-state set
-    77 basic-block set
     compute-local-kill-set
 ] unit-test
-
-{ D 2 } [
-    { { 1 2 } { 3 4 } } D 3 translate-local-loc
-] unit-test
diff --git a/basis/compiler/cfg/stacks/local/local.factor b/basis/compiler/cfg/stacks/local/local.factor
index a545ccf00c..f8d9c7ec5b 100644
--- a/basis/compiler/cfg/stacks/local/local.factor
+++ b/basis/compiler/cfg/stacks/local/local.factor
@@ -7,6 +7,9 @@ hash-sets kernel make math math.order namespaces sequences sets ;
 FROM: namespaces => set ;
 IN: compiler.cfg.stacks.local
 
+: current-height ( state -- ds rs )
+    first2 [ first ] bi@ ;
+
 : >loc< ( loc -- n ds? )
     [ n>> ] [ ds-loc? ] bi ;
 
@@ -23,8 +26,8 @@ IN: compiler.cfg.stacks.local
     [ second ] map { ds-loc rs-loc } [ new swap >>n ] 2map
     [ n>> 0 = not ] filter [ ##inc new swap >>loc ] map ;
 
-: translate-local-loc ( state loc -- loc' )
-    >loc< [ 0 1 ? rot nth first - ] keep ds-loc rs-loc ? new swap >>n ;
+: translate-local-loc ( loc state -- loc' )
+    [ clone ] dip over >loc< 0 1 ? rot nth first - >>n ;
 
 : clone-height-state ( state -- state' )
     [ clone ] map ;
@@ -36,7 +39,7 @@ IN: compiler.cfg.stacks.local
     dupd [-] iota [ swap - ] with map ;
 
 : local-kill-set ( ds-height rs-height state -- set )
-    first2 [ first ] bi@ swapd [ kill-locations ] 2bi@
+    current-height swapd [ kill-locations ] 2bi@
     [ [ <ds-loc> ] map ] [ [ <rs-loc> ] map ] bi*
     append >hash-set ;
 
@@ -48,43 +51,42 @@ SYMBOLS: height-state peek-sets replace-sets kill-sets locs>vregs ;
 : loc>vreg ( loc -- vreg ) locs>vregs get [ drop next-vreg ] cache ;
 : vreg>loc ( vreg -- loc/f ) locs>vregs get value-at ;
 
-SYMBOLS: local-peek-set replace-mapping ;
+SYMBOLS: local-peek-set replaces ;
 
-: stack-changes ( replace-mapping -- insns )
+: replaces>copy-insns ( replaces -- insns )
     [ [ loc>vreg ] dip ] assoc-map parallel-copy ;
 
-: emit-changes ( replace-mapping height-state -- )
-    building get pop -rot [ stack-changes % ] [ height-state>insns % ] bi* , ;
+: changes>insns ( replaces height-state -- insns )
+    [ replaces>copy-insns ] [ height-state>insns ] bi* append ;
+
+: emit-changes ( replaces height-state -- )
+    building get pop -rot changes>insns % , ;
 
 : peek-loc ( loc -- vreg )
-    height-state get swap translate-local-loc
-    dup replace-mapping get at
+    height-state get translate-local-loc dup replaces get at
     [ ] [ dup local-peek-set get adjoin loc>vreg ] ?if ;
 
 : replace-loc ( vreg loc -- )
-    height-state get swap translate-local-loc
-    replace-mapping get set-at ;
+    height-state get translate-local-loc replaces get set-at ;
 
-: compute-local-kill-set ( -- set )
-    basic-block get [ rs-heights get at ] [ ds-heights get at ] bi
+: compute-local-kill-set ( basic-block -- set )
+    [ rs-heights get at ] [ ds-heights get at ] bi
     height-state get local-kill-set ;
 
-: begin-local-analysis ( -- )
+: begin-local-analysis ( basic-block -- )
+    height-state get dup reset-emits
+    current-height rot record-stack-heights
     HS{ } clone local-peek-set set
-    H{ } clone replace-mapping set
-    height-state get
-    [ reset-emits ] [
-        first2 [ first ] bi@ basic-block get record-stack-heights
-    ] bi ;
+    H{ } clone replaces set ;
 
-: remove-redundant-replaces ( replace-mapping -- replace-mapping' )
+: remove-redundant-replaces ( replaces -- replaces' )
     [ [ loc>vreg ] dip = not ] assoc-filter ;
 
 : end-local-analysis ( basic-block -- )
     [
-        replace-mapping get remove-redundant-replaces
+        replaces get remove-redundant-replaces
         dup height-state get emit-changes keys
         swap replace-sets get set-at
     ]
     [ [ local-peek-set get ] dip peek-sets get set-at ]
-    [ [ compute-local-kill-set ] dip kill-sets get set-at ] tri ;
+    [ [ compute-local-kill-set ] keep kill-sets get set-at ] tri ;
diff --git a/basis/compiler/cfg/stacks/stacks-tests.factor b/basis/compiler/cfg/stacks/stacks-tests.factor
index ee8736ed24..76f9b00c2a 100644
--- a/basis/compiler/cfg/stacks/stacks-tests.factor
+++ b/basis/compiler/cfg/stacks/stacks-tests.factor
@@ -8,7 +8,7 @@ IN: compiler.cfg.stacks.tests
     { { 0 0 } { 0 0 } }
 } [
     { 3 4 5 } ds-loc store-vregs
-    replace-mapping get
+    replaces get
     height-state get
 ] cfg-unit-test
 
diff --git a/basis/compiler/test/test.factor b/basis/compiler/test/test.factor
index d7bf44bada..8747123837 100644
--- a/basis/compiler/test/test.factor
+++ b/basis/compiler/test/test.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2010 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors arrays compiler.units kernel sequences
+USING: accessors arrays compiler.cfg compiler.units kernel sequences
 stack-checker tools.test vocabs words ;
 IN: compiler.test
 
@@ -22,8 +22,9 @@ USING: compiler.cfg.registers compiler.cfg.stacks compiler.cfg.stacks.local
 fry namespaces ;
 
 : init-cfg-test ( -- )
-    reset-vreg-counter begin-stack-analysis begin-local-analysis
-    H{ } clone replace-mapping set ;
+    reset-vreg-counter begin-stack-analysis
+    <basic-block> dup basic-block set begin-local-analysis
+    H{ } clone replaces set ;
 
 : cfg-unit-test ( result quot -- )
     '[ init-cfg-test @ ] unit-test ; inline