diff --git a/basis/compiler/cfg/block-joining/block-joining.factor b/basis/compiler/cfg/block-joining/block-joining.factor
new file mode 100644
index 0000000000..982f0866e6
--- /dev/null
+++ b/basis/compiler/cfg/block-joining/block-joining.factor
@@ -0,0 +1,43 @@
+! Copyright (C) 2009 Slava Pestov.
+! See http://factorcode.org/license.txt for BSD license.
+USING: accessors combinators.short-circuit kernel sequences math
+compiler.utilities compiler.cfg compiler.cfg.instructions compiler.cfg.rpo
+compiler.cfg.utilities ;
+IN: compiler.cfg.block-joining
+
+! Joining blocks that are not calls and are connected by a single CFG edge.
+! Predecessors must be recomputed after this. Also this pass does not
+! update ##phi nodes and should therefore only run before stack analysis.
+
+: kill-vreg-block? ( bb -- ? )
+    instructions>> {
+        [ length 2 >= ]
+        [ penultimate kill-vreg-insn? ]
+    } 1&& ;
+
+: predecessor ( bb -- pred )
+    predecessors>> first ; inline
+
+: join-block? ( bb -- ? )
+    {
+        [ predecessors>> length 1 = ]
+        [ predecessor kill-vreg-block? not ]
+        [ predecessor successors>> length 1 = ]
+        [ [ predecessor ] keep back-edge? not ]
+    } 1&& ;
+
+: join-instructions ( bb pred -- )
+    [ instructions>> ] bi@ dup pop* push-all ;
+
+: update-successors ( bb pred -- )
+    [ successors>> ] dip (>>successors) ;
+
+: join-block ( bb pred -- )
+    [ join-instructions ] [ update-successors ] 2bi ;
+
+: join-blocks ( cfg -- cfg' )
+    dup post-order [
+        dup join-block?
+        [ dup predecessor join-block ] [ drop ] if
+    ] each
+    cfg-changed ;
diff --git a/basis/compiler/cfg/branch-splitting/branch-splitting-tests.factor b/basis/compiler/cfg/branch-splitting/branch-splitting-tests.factor
index fbaaf92203..89f26f7928 100644
--- a/basis/compiler/cfg/branch-splitting/branch-splitting-tests.factor
+++ b/basis/compiler/cfg/branch-splitting/branch-splitting-tests.factor
@@ -1,6 +1,6 @@
 USING: accessors assocs compiler.cfg
 compiler.cfg.branch-splitting compiler.cfg.debugger
-compiler.cfg.predecessors compiler.cfg.rpo fry kernel
+compiler.cfg.predecessors compiler.cfg.rpo compiler.cfg.instructions fry kernel
 tools.test namespaces sequences vectors ;
 IN: compiler.cfg.branch-splitting.tests
 
@@ -20,31 +20,31 @@ IN: compiler.cfg.branch-splitting.tests
 : test-branch-splitting ( -- )
     cfg new 0 get >>entry check-branch-splitting ;
 
-V{ } 0 test-bb
+V{ T{ ##branch } } 0 test-bb
 
-V{ } 1 test-bb
+V{ T{ ##branch } } 1 test-bb
 
-V{ } 2 test-bb
+V{ T{ ##branch } } 2 test-bb
 
-V{ } 3 test-bb
+V{ T{ ##branch } } 3 test-bb
 
-V{ } 4 test-bb
+V{ T{ ##branch } } 4 test-bb
 
 test-diamond
 
 [ ] [ test-branch-splitting ] unit-test
 
-V{ } 0 test-bb
+V{ T{ ##branch } } 0 test-bb
 
-V{ } 1 test-bb
+V{ T{ ##branch } } 1 test-bb
 
-V{ } 2 test-bb
+V{ T{ ##branch } } 2 test-bb
 
-V{ } 3 test-bb
+V{ T{ ##branch } } 3 test-bb
 
-V{ } 4 test-bb
+V{ T{ ##branch } } 4 test-bb
 
-V{ } 5 test-bb
+V{ T{ ##branch } } 5 test-bb
 
 0 get 1 get 2 get V{ } 2sequence >>successors drop
 
@@ -54,15 +54,15 @@ V{ } 5 test-bb
 
 [ ] [ test-branch-splitting ] unit-test
 
-V{ } 0 test-bb
+V{ T{ ##branch } } 0 test-bb
 
-V{ } 1 test-bb
+V{ T{ ##branch } } 1 test-bb
 
-V{ } 2 test-bb
+V{ T{ ##branch } } 2 test-bb
 
-V{ } 3 test-bb
+V{ T{ ##branch } } 3 test-bb
 
-V{ } 4 test-bb
+V{ T{ ##branch } } 4 test-bb
 
 0 get 1 get 2 get V{ } 2sequence >>successors drop
 
@@ -72,11 +72,11 @@ V{ } 4 test-bb
 
 [ ] [ test-branch-splitting ] unit-test
 
-V{ } 0 test-bb
+V{ T{ ##branch } } 0 test-bb
 
-V{ } 1 test-bb
+V{ T{ ##branch } } 1 test-bb
 
-V{ } 2 test-bb
+V{ T{ ##branch } } 2 test-bb
 
 0 get 1 get 2 get V{ } 2sequence >>successors drop
 
diff --git a/basis/compiler/cfg/branch-splitting/branch-splitting.factor b/basis/compiler/cfg/branch-splitting/branch-splitting.factor
index 9d6e59e4da..2ab476e20c 100644
--- a/basis/compiler/cfg/branch-splitting/branch-splitting.factor
+++ b/basis/compiler/cfg/branch-splitting/branch-splitting.factor
@@ -63,7 +63,9 @@ IN: compiler.cfg.branch-splitting
 UNION: irrelevant ##peek ##replace ##inc-d ##inc-r ;
 
 : split-instructions? ( insns -- ? )
-    [ irrelevant? not ] count 5 <= ;
+    [ [ irrelevant? not ] count 5 <= ]
+    [ last ##fixnum-overflow? not ]
+    bi and ;
 
 : split-branch? ( bb -- ? )
     {
diff --git a/basis/compiler/cfg/build-stack-frame/build-stack-frame.factor b/basis/compiler/cfg/build-stack-frame/build-stack-frame.factor
index e5be2d9eb9..71798da6fc 100644
--- a/basis/compiler/cfg/build-stack-frame/build-stack-frame.factor
+++ b/basis/compiler/cfg/build-stack-frame/build-stack-frame.factor
@@ -1,4 +1,4 @@
-! Copyright (C) 2008 Slava Pestov.
+! Copyright (C) 2008, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: namespaces accessors math.order assocs kernel sequences
 combinators make classes words cpu.architecture
@@ -36,12 +36,6 @@ M: insn compute-stack-frame*
     ] when ;
 
 \ _spill t frame-required? set-word-prop
-\ ##fixnum-add t frame-required? set-word-prop
-\ ##fixnum-sub t frame-required? set-word-prop
-\ ##fixnum-mul t frame-required? set-word-prop
-\ ##fixnum-add-tail f frame-required? set-word-prop
-\ ##fixnum-sub-tail f frame-required? set-word-prop
-\ ##fixnum-mul-tail f frame-required? set-word-prop
 
 : compute-stack-frame ( insns -- )
     frame-required? off
diff --git a/basis/compiler/cfg/builder/builder.factor b/basis/compiler/cfg/builder/builder.factor
index 991fd2e20d..c866835ac5 100755
--- a/basis/compiler/cfg/builder/builder.factor
+++ b/basis/compiler/cfg/builder/builder.factor
@@ -98,17 +98,10 @@ M: #recursive emit-node
 
 ! #if
 : emit-branch ( obj -- final-bb )
-    [
-        begin-basic-block
-        emit-nodes
-        basic-block get dup [ ##branch ] when
-    ] with-scope ;
+    [ emit-nodes ] with-branch ;
 
 : emit-if ( node -- )
-    children>> [ emit-branch ] map
-    end-basic-block
-    begin-basic-block
-    basic-block get '[ [ _ swap successors>> push ] when* ] each ;
+    children>> [ emit-branch ] map emit-conditional ;
 
 : ##branch-t ( vreg -- )
     \ f tag-number cc/= ##compare-imm-branch ;
diff --git a/basis/compiler/cfg/checker/checker.factor b/basis/compiler/cfg/checker/checker.factor
index e7d9dbdd9c..49ea775600 100644
--- a/basis/compiler/cfg/checker/checker.factor
+++ b/basis/compiler/cfg/checker/checker.factor
@@ -16,9 +16,9 @@ ERROR: last-insn-not-a-jump insn ;
         [ ##return? ]
         [ ##callback-return? ]
         [ ##jump? ]
-        [ ##fixnum-add-tail? ]
-        [ ##fixnum-sub-tail? ]
-        [ ##fixnum-mul-tail? ]
+        [ ##fixnum-add? ]
+        [ ##fixnum-sub? ]
+        [ ##fixnum-mul? ]
         [ ##no-tco? ]
     } 1|| [ drop ] [ last-insn-not-a-jump ] if ;
 
diff --git a/basis/compiler/cfg/def-use/def-use.factor b/basis/compiler/cfg/def-use/def-use.factor
index 43ea89f284..c8a9d1861b 100644
--- a/basis/compiler/cfg/def-use/def-use.factor
+++ b/basis/compiler/cfg/def-use/def-use.factor
@@ -8,6 +8,7 @@ GENERIC: temp-vregs ( insn -- seq )
 GENERIC: uses-vregs ( insn -- seq )
 
 M: ##flushable defs-vregs dst>> 1array ;
+M: ##fixnum-overflow defs-vregs dst>> 1array ;
 M: insn defs-vregs drop f ;
 
 M: ##write-barrier temp-vregs [ card#>> ] [ table>> ] bi 2array ;
@@ -21,8 +22,6 @@ M: ##set-string-nth-fast temp-vregs temp>> 1array ;
 M: ##compare temp-vregs temp>> 1array ;
 M: ##compare-imm temp-vregs temp>> 1array ;
 M: ##compare-float temp-vregs temp>> 1array ;
-M: ##fixnum-mul temp-vregs [ temp1>> ] [ temp2>> ] bi 2array ;
-M: ##fixnum-mul-tail temp-vregs [ temp1>> ] [ temp2>> ] bi 2array ;
 M: ##gc temp-vregs [ temp1>> ] [ temp2>> ] bi 2array ;
 M: _dispatch temp-vregs temp>> 1array ;
 M: insn temp-vregs drop f ;
diff --git a/basis/compiler/cfg/hats/hats.factor b/basis/compiler/cfg/hats/hats.factor
index b61f091fad..986438d055 100644
--- a/basis/compiler/cfg/hats/hats.factor
+++ b/basis/compiler/cfg/hats/hats.factor
@@ -73,5 +73,7 @@ IN: compiler.cfg.hats
 : ^^offset>slot ( vreg -- vreg' ) cell 4 = [ 1 ^^shr-imm ] when ; inline
 : ^^tag-fixnum ( src -- dst ) ^^i1 ##tag-fixnum ; inline
 : ^^untag-fixnum ( src -- dst ) ^^i1 ##untag-fixnum ; inline
-
+: ^^fixnum-add ( src1 src2 -- dst ) ^^i2 ##fixnum-add ; inline
+: ^^fixnum-sub ( src1 src2 -- dst ) ^^i2 ##fixnum-sub ; inline
+: ^^fixnum-mul ( src1 src2 -- dst ) ^^i2 ##fixnum-mul ; inline
 : ^^phi ( inputs -- dst ) ^^i1 ##phi ; inline
\ No newline at end of file
diff --git a/basis/compiler/cfg/instructions/instructions.factor b/basis/compiler/cfg/instructions/instructions.factor
index 910cb1992b..8d4b0f40ad 100644
--- a/basis/compiler/cfg/instructions/instructions.factor
+++ b/basis/compiler/cfg/instructions/instructions.factor
@@ -92,15 +92,6 @@ INSN: ##sar-imm < ##binary-imm ;
 INSN: ##not < ##unary ;
 INSN: ##log2 < ##unary ;
 
-! Overflowing arithmetic
-TUPLE: ##fixnum-overflow < insn src1 src2 ;
-INSN: ##fixnum-add < ##fixnum-overflow ;
-INSN: ##fixnum-add-tail < ##fixnum-overflow ;
-INSN: ##fixnum-sub < ##fixnum-overflow ;
-INSN: ##fixnum-sub-tail < ##fixnum-overflow ;
-INSN: ##fixnum-mul < ##fixnum-overflow temp1 temp2 ;
-INSN: ##fixnum-mul-tail < ##fixnum-overflow temp1 temp2 ;
-
 : ##tag-fixnum ( dst src -- ) tag-bits get ##shl-imm ; inline
 : ##untag-fixnum ( dst src -- ) tag-bits get ##sar-imm ; inline
 
@@ -181,6 +172,7 @@ INSN: ##loop-entry ;
 
 INSN: ##phi < ##pure inputs ;
 
+! Conditionals
 TUPLE: ##conditional-branch < insn { src1 vreg } { src2 vreg } cc ;
 
 INSN: ##compare-branch < ##conditional-branch ;
@@ -192,6 +184,12 @@ INSN: ##compare-imm < ##binary-imm cc temp ;
 INSN: ##compare-float-branch < ##conditional-branch ;
 INSN: ##compare-float < ##binary cc temp ;
 
+! Overflowing arithmetic
+TUPLE: ##fixnum-overflow < insn { dst vreg } { src1 vreg } { src2 vreg } ;
+INSN: ##fixnum-add < ##fixnum-overflow ;
+INSN: ##fixnum-sub < ##fixnum-overflow ;
+INSN: ##fixnum-mul < ##fixnum-overflow ;
+
 INSN: ##gc { temp1 vreg } { temp2 vreg } live-values ;
 
 ! Instructions used by machine IR only.
@@ -212,6 +210,12 @@ INSN: _compare-imm-branch label { src1 vreg } { src2 integer } cc ;
 
 INSN: _compare-float-branch < _conditional-branch ;
 
+! Overflowing arithmetic
+TUPLE: _fixnum-overflow < insn label { dst vreg } { src1 vreg } { src2 vreg } ;
+INSN: _fixnum-add < _fixnum-overflow ;
+INSN: _fixnum-sub < _fixnum-overflow ;
+INSN: _fixnum-mul < _fixnum-overflow ;
+
 TUPLE: spill-slot n ; C: <spill-slot> spill-slot
 
 INSN: _gc { temp1 vreg } { temp2 vreg } gc-roots gc-root-count gc-root-size ;
@@ -223,3 +227,19 @@ INSN: _reload dst class n ;
 INSN: _copy dst src class ;
 INSN: _spill-counts counts ;
 
+! Instructions that poison the stack state
+UNION: poison-insn
+    ##jump
+    ##return
+    ##callback-return ;
+
+! Instructions that kill all live vregs
+UNION: kill-vreg-insn
+    poison-insn
+    ##stack-frame
+    ##call
+    ##prologue
+    ##epilogue
+    ##alien-invoke
+    ##alien-indirect
+    ##alien-callback ;
diff --git a/basis/compiler/cfg/intrinsics/fixnum/fixnum.factor b/basis/compiler/cfg/intrinsics/fixnum/fixnum.factor
index 2a82139e13..57eb7fb63c 100644
--- a/basis/compiler/cfg/intrinsics/fixnum/fixnum.factor
+++ b/basis/compiler/cfg/intrinsics/fixnum/fixnum.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2008, 2009 Slava Pestov, Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: sequences accessors layouts kernel math namespaces
-combinators fry
+combinators fry arrays
 compiler.tree.propagation.info
 compiler.cfg.hats
 compiler.cfg.stacks
@@ -54,6 +54,28 @@ IN: compiler.cfg.intrinsics.fixnum
 : emit-fixnum>bignum ( -- )
     ds-pop ^^untag-fixnum ^^integer>bignum ds-push ;
 
-: emit-fixnum-overflow-op ( quot -- next )
-    [ 2inputs 1 ##inc-d ] dip call ##branch
-    begin-basic-block ; inline
+: emit-no-overflow-case ( dst -- final-bb )
+    [ -2 ##inc-d ds-push ] with-branch ;
+
+: emit-overflow-case ( word -- final-bb )
+    [ ##call ] with-branch ;
+
+: emit-fixnum-overflow-op ( quot word -- )
+    [ [ D 1 ^^peek D 0 ^^peek ] dip call ] dip
+    [ emit-no-overflow-case ] [ emit-overflow-case ] bi* 2array
+    emit-conditional ; inline
+
+: fixnum+overflow ( x y -- z ) [ >bignum ] bi@ + ;
+
+: fixnum-overflow ( x y -- z ) [ >bignum ] bi@ - ;
+
+: fixnum*overflow ( x y -- z ) [ >bignum ] bi@ * ;
+
+: emit-fixnum+ ( -- )
+    [ ^^fixnum-add ] \ fixnum+overflow emit-fixnum-overflow-op ;
+
+: emit-fixnum- ( -- )
+    [ ^^fixnum-sub ] \ fixnum-overflow emit-fixnum-overflow-op ;
+
+: emit-fixnum* ( -- )
+    [ ^^untag-fixnum ^^fixnum-mul ] \ fixnum*overflow emit-fixnum-overflow-op ;
\ No newline at end of file
diff --git a/basis/compiler/cfg/intrinsics/intrinsics.factor b/basis/compiler/cfg/intrinsics/intrinsics.factor
index ed94ec36d9..e4a7b8972a 100644
--- a/basis/compiler/cfg/intrinsics/intrinsics.factor
+++ b/basis/compiler/cfg/intrinsics/intrinsics.factor
@@ -100,9 +100,9 @@ IN: compiler.cfg.intrinsics
         { \ kernel.private:tag [ drop emit-tag ] }
         { \ kernel.private:getenv [ emit-getenv ] }
         { \ math.private:both-fixnums? [ drop emit-both-fixnums? ] }
-        { \ math.private:fixnum+ [ drop [ ##fixnum-add ] emit-fixnum-overflow-op ] }
-        { \ math.private:fixnum- [ drop [ ##fixnum-sub ] emit-fixnum-overflow-op ] }
-        { \ math.private:fixnum* [ drop [ i i ##fixnum-mul ] emit-fixnum-overflow-op ] }
+        { \ math.private:fixnum+ [ drop emit-fixnum+ ] }
+        { \ math.private:fixnum- [ drop emit-fixnum- ] }
+        { \ math.private:fixnum* [ drop emit-fixnum* ] }
         { \ math.private:fixnum+fast [ drop [ ^^add ] emit-fixnum-op ] }
         { \ math.private:fixnum-fast [ drop [ ^^sub ] emit-fixnum-op ] }
         { \ math.private:fixnum-bitand [ drop [ ^^and ] emit-fixnum-op ] }
diff --git a/basis/compiler/cfg/linear-scan/linear-scan-tests.factor b/basis/compiler/cfg/linear-scan/linear-scan-tests.factor
index fd95a3e09c..63da100b02 100644
--- a/basis/compiler/cfg/linear-scan/linear-scan-tests.factor
+++ b/basis/compiler/cfg/linear-scan/linear-scan-tests.factor
@@ -2159,12 +2159,7 @@ V{
     T{ ##replace { src V int-regs 85 } { loc D 1 } }
     T{ ##replace { src V int-regs 89 } { loc D 4 } }
     T{ ##replace { src V int-regs 96 } { loc R 0 } }
-    T{ ##fixnum-mul
-        { src1 V int-regs 128 }
-        { src2 V int-regs 129 }
-        { temp1 V int-regs 132 }
-        { temp2 V int-regs 133 }
-    }
+    T{ ##replace { src V int-regs 129 } { loc R 0 } }
     T{ ##branch }
 } 2 test-bb
 
@@ -2255,206 +2250,6 @@ V{
 
 [ ] [ { 1 2 3 4 5 } test-linear-scan-on-cfg ] unit-test
 
-! Another push-all reduction to demonstrate numbering anamoly
-V{ T{ ##prologue } T{ ##branch } }
-0 test-bb
-
-V{
-    T{ ##peek { dst V int-regs 1 } { loc D 0 } }
-    T{ ##slot-imm
-        { dst V int-regs 5 }
-        { obj V int-regs 1 }
-        { slot 3 }
-        { tag 7 }
-    }
-    T{ ##peek { dst V int-regs 7 } { loc D 1 } }
-    T{ ##slot-imm
-        { dst V int-regs 12 }
-        { obj V int-regs 7 }
-        { slot 1 }
-        { tag 6 }
-    }
-    T{ ##add
-        { dst V int-regs 25 }
-        { src1 V int-regs 5 }
-        { src2 V int-regs 12 }
-    }
-    T{ ##compare-branch
-        { src1 V int-regs 25 }
-        { src2 V int-regs 5 }
-        { cc cc> }
-    }
-}
-1 test-bb
-
-V{
-    T{ ##slot-imm
-        { dst V int-regs 41 }
-        { obj V int-regs 1 }
-        { slot 2 }
-        { tag 7 }
-    }
-    T{ ##slot-imm
-        { dst V int-regs 44 }
-        { obj V int-regs 41 }
-        { slot 1 }
-        { tag 6 }
-    }
-    T{ ##compare-branch
-        { src1 V int-regs 25 }
-        { src2 V int-regs 44 }
-        { cc cc> }
-    }
-}
-2 test-bb
-
-V{
-    T{ ##add-imm
-        { dst V int-regs 54 }
-        { src1 V int-regs 25 }
-        { src2 8 }
-    }
-    T{ ##load-immediate { dst V int-regs 55 } { val 24 } }
-    T{ ##inc-d { n 4 } }
-    T{ ##inc-r { n 1 } }
-    T{ ##replace { src V int-regs 25 } { loc D 2 } }
-    T{ ##replace { src V int-regs 1 } { loc D 3 } }
-    T{ ##replace { src V int-regs 5 } { loc D 4 } }
-    T{ ##replace { src V int-regs 1 } { loc D 1 } }
-    T{ ##replace { src V int-regs 54 } { loc D 0 } }
-    T{ ##replace { src V int-regs 12 } { loc R 0 } }
-    T{ ##fixnum-mul
-        { src1 V int-regs 54 }
-        { src2 V int-regs 55 }
-        { temp1 V int-regs 58 }
-        { temp2 V int-regs 59 }
-    }
-    T{ ##branch }
-}
-3 test-bb
-
-V{
-    T{ ##peek { dst V int-regs 60 } { loc D 1 } }
-    T{ ##slot-imm
-        { dst V int-regs 66 }
-        { obj V int-regs 60 }
-        { slot 2 }
-        { tag 7 }
-    }
-    T{ ##inc-d { n 1 } }
-    T{ ##inc-r { n 1 } }
-    T{ ##replace { src V int-regs 66 } { loc D 0 } }
-    T{ ##replace { src V int-regs 60 } { loc R 0 } }
-    T{ ##call { word resize-string } }
-    T{ ##branch }
-}
-4 test-bb
-
-V{
-    T{ ##peek { dst V int-regs 67 } { loc R 0 } }
-    T{ ##peek { dst V int-regs 68 } { loc D 0 } }
-    T{ ##set-slot-imm
-        { src V int-regs 68 }
-        { obj V int-regs 67 }
-        { slot 2 }
-        { tag 7 }
-    }
-    T{ ##write-barrier
-        { src V int-regs 67 }
-        { card# V int-regs 75 }
-        { table V int-regs 76 }
-    }
-    T{ ##inc-d { n -1 } }
-    T{ ##inc-r { n -1 } }
-    T{ ##peek { dst V int-regs 94 } { loc D 0 } }
-    T{ ##peek { dst V int-regs 96 } { loc D 1 } }
-    T{ ##peek { dst V int-regs 98 } { loc D 2 } }
-    T{ ##peek { dst V int-regs 100 } { loc D 3 } }
-    T{ ##peek { dst V int-regs 102 } { loc D 4 } }
-    T{ ##peek { dst V int-regs 106 } { loc R 0 } }
-    T{ ##copy { dst V int-regs 95 } { src V int-regs 94 } }
-    T{ ##copy { dst V int-regs 97 } { src V int-regs 96 } }
-    T{ ##copy { dst V int-regs 99 } { src V int-regs 98 } }
-    T{ ##copy { dst V int-regs 101 } { src V int-regs 100 } }
-    T{ ##copy { dst V int-regs 103 } { src V int-regs 102 } }
-    T{ ##copy { dst V int-regs 107 } { src V int-regs 106 } }
-    T{ ##branch }
-}
-5 test-bb
-
-V{
-    T{ ##inc-d { n 3 } }
-    T{ ##inc-r { n 1 } }
-    T{ ##copy { dst V int-regs 95 } { src V int-regs 1 } }
-    T{ ##copy { dst V int-regs 97 } { src V int-regs 25 } }
-    T{ ##copy { dst V int-regs 99 } { src V int-regs 1 } }
-    T{ ##copy { dst V int-regs 101 } { src V int-regs 5 } }
-    T{ ##copy { dst V int-regs 103 } { src V int-regs 7 } }
-    T{ ##copy { dst V int-regs 107 } { src V int-regs 12 } }
-    T{ ##branch }
-}
-6 test-bb
-
-V{
-    T{ ##load-immediate
-        { dst V int-regs 78 }
-        { val 4611686018427387896 }
-    }
-    T{ ##and
-        { dst V int-regs 81 }
-        { src1 V int-regs 97 }
-        { src2 V int-regs 78 }
-    }
-    T{ ##set-slot-imm
-        { src V int-regs 81 }
-        { obj V int-regs 95 }
-        { slot 3 }
-        { tag 7 }
-    }
-    T{ ##inc-d { n -2 } }
-    T{ ##copy { dst V int-regs 110 } { src V int-regs 99 } }
-    T{ ##copy { dst V int-regs 111 } { src V int-regs 101 } }
-    T{ ##copy { dst V int-regs 112 } { src V int-regs 103 } }
-    T{ ##copy { dst V int-regs 117 } { src V int-regs 107 } }
-    T{ ##branch }
-}
-7 test-bb
-
-V{
-    T{ ##inc-d { n 1 } }
-    T{ ##inc-r { n 1 } }
-    T{ ##copy { dst V int-regs 110 } { src V int-regs 1 } }
-    T{ ##copy { dst V int-regs 111 } { src V int-regs 5 } }
-    T{ ##copy { dst V int-regs 112 } { src V int-regs 7 } }
-    T{ ##copy { dst V int-regs 117 } { src V int-regs 12 } }
-    T{ ##branch }
-}
-8 test-bb
-
-V{
-    T{ ##inc-d { n 1 } }
-    T{ ##inc-r { n -1 } }
-    T{ ##replace { src V int-regs 117 } { loc D 0 } }
-    T{ ##replace { src V int-regs 110 } { loc D 1 } }
-    T{ ##replace { src V int-regs 111 } { loc D 2 } }
-    T{ ##replace { src V int-regs 112 } { loc D 3 } }
-    T{ ##epilogue }
-    T{ ##return }
-}
-9 test-bb
-
-0 get 1 get 1vector >>successors drop
-1 get 2 get 8 get V{ } 2sequence >>successors drop
-2 get 3 get 6 get V{ } 2sequence >>successors drop
-3 get 4 get 1vector >>successors drop
-4 get 5 get 1vector >>successors drop
-5 get 7 get 1vector >>successors drop
-6 get 7 get 1vector >>successors drop
-7 get 9 get 1vector >>successors drop
-8 get 9 get 1vector >>successors drop
-
-[ ] [ { 1 2 3 4 5 } test-linear-scan-on-cfg ] unit-test
-
 ! Fencepost error in assignment pass
 V{ T{ ##branch } } 0 test-bb
 
diff --git a/basis/compiler/cfg/linear-scan/live-intervals/live-intervals.factor b/basis/compiler/cfg/linear-scan/live-intervals/live-intervals.factor
index bf7e8bc042..d2fa661136 100644
--- a/basis/compiler/cfg/linear-scan/live-intervals/live-intervals.factor
+++ b/basis/compiler/cfg/linear-scan/live-intervals/live-intervals.factor
@@ -122,10 +122,10 @@ M: ##copy-float compute-live-intervals*
     dup ranges>> [ first from>> ] [ last to>> ] bi
     [ >>start ] [ >>end ] bi* drop ;
 
-: check-start/end ( live-interval -- )
-    [ [ start>> ] [ uses>> first ] bi assert= ]
-    [ [ end>> ] [ uses>> last ] bi assert= ]
-    bi ;
+ERROR: bad-live-interval live-interval ;
+
+: check-start ( live-interval -- )
+    dup start>> -1 = [ bad-live-interval ] [ drop ] if ;
 
 : finish-live-intervals ( live-intervals -- )
     ! Since live intervals are computed in a backward order, we have
@@ -135,7 +135,7 @@ M: ##copy-float compute-live-intervals*
             [ ranges>> reverse-here ]
             [ uses>> reverse-here ]
             [ compute-start/end ]
-            [ check-start/end ]
+            [ check-start ]
         } cleave
     ] each ;
 
diff --git a/basis/compiler/cfg/linearization/linearization.factor b/basis/compiler/cfg/linearization/linearization.factor
index a75ac064d9..9faa1e9e38 100755
--- a/basis/compiler/cfg/linearization/linearization.factor
+++ b/basis/compiler/cfg/linearization/linearization.factor
@@ -31,8 +31,10 @@ M: insn linearize-insn , drop ;
 M: ##branch linearize-insn
     drop dup successors>> first emit-branch ;
 
+: successors ( bb -- first second ) successors>> first2 ; inline
+
 : (binary-conditional) ( basic-block insn -- basic-block successor1 successor2 src1 src2 cc )
-    [ dup successors>> first2 ]
+    [ dup successors ]
     [ [ src1>> ] [ src2>> ] [ cc>> ] tri ] bi* ; inline
 
 : binary-conditional ( basic-block insn -- basic-block successor label2 src1 src2 cc )
@@ -52,6 +54,19 @@ M: ##compare-imm-branch linearize-insn
 M: ##compare-float-branch linearize-insn
     [ binary-conditional _compare-float-branch ] with-regs emit-branch ;
 
+: overflow-conditional ( basic-block insn -- basic-block successor label2 dst src1 src2 )
+    [ dup successors number>> ]
+    [ [ dst>> ] [ src1>> ] [ src2>> ] tri ] bi* ; inline
+
+M: ##fixnum-add linearize-insn
+    [ overflow-conditional _fixnum-add ] with-regs emit-branch ;
+
+M: ##fixnum-sub linearize-insn
+    [ overflow-conditional _fixnum-sub ] with-regs emit-branch ;
+
+M: ##fixnum-mul linearize-insn
+    [ overflow-conditional _fixnum-mul ] with-regs emit-branch ;
+
 M: ##dispatch linearize-insn
     swap
     [ [ [ src>> ] [ temp>> ] bi _dispatch ] with-regs ]
diff --git a/basis/compiler/cfg/optimizer/optimizer.factor b/basis/compiler/cfg/optimizer/optimizer.factor
index e16fb734e1..1af0fcbc53 100644
--- a/basis/compiler/cfg/optimizer/optimizer.factor
+++ b/basis/compiler/cfg/optimizer/optimizer.factor
@@ -6,6 +6,7 @@ compiler.cfg.predecessors
 compiler.cfg.useless-conditionals
 compiler.cfg.stack-analysis
 compiler.cfg.branch-splitting
+compiler.cfg.block-joining
 compiler.cfg.alias-analysis
 compiler.cfg.value-numbering
 compiler.cfg.dce
@@ -31,6 +32,8 @@ SYMBOL: check-optimizer?
         delete-useless-conditionals
         compute-predecessors
         split-branches
+        join-blocks
+        compute-predecessors
         stack-analysis
         compute-liveness
         alias-analysis
diff --git a/basis/compiler/cfg/renaming/renaming.factor b/basis/compiler/cfg/renaming/renaming.factor
index 228d72483c..efc841e21f 100644
--- a/basis/compiler/cfg/renaming/renaming.factor
+++ b/basis/compiler/cfg/renaming/renaming.factor
@@ -136,16 +136,6 @@ M: ##compare-imm fresh-insn-temps
 M: ##compare-float fresh-insn-temps
     [ fresh-vreg ] change-temp drop ;
 
-M: ##fixnum-mul fresh-insn-temps
-    [ fresh-vreg ] change-temp1
-    [ fresh-vreg ] change-temp2
-    drop ;
-
-M: ##fixnum-mul-tail fresh-insn-temps
-    [ fresh-vreg ] change-temp1
-    [ fresh-vreg ] change-temp2
-    drop ;
-
 M: ##gc fresh-insn-temps
     [ fresh-vreg ] change-temp1
     [ fresh-vreg ] change-temp2
diff --git a/basis/compiler/cfg/stack-analysis/merge/merge.factor b/basis/compiler/cfg/stack-analysis/merge/merge.factor
index cb0ad7d615..a53fd7494e 100644
--- a/basis/compiler/cfg/stack-analysis/merge/merge.factor
+++ b/basis/compiler/cfg/stack-analysis/merge/merge.factor
@@ -92,6 +92,7 @@ SYMBOL: added-phis
 :: multiple-predecessors ( bb states -- state )
     states [ not ] any? [
         <state>
+        bb add-to-work-list
     ] [
         [
             H{ } clone added-instructions set
diff --git a/basis/compiler/cfg/stack-analysis/stack-analysis.factor b/basis/compiler/cfg/stack-analysis/stack-analysis.factor
index 48a4b79783..e46460a741 100644
--- a/basis/compiler/cfg/stack-analysis/stack-analysis.factor
+++ b/basis/compiler/cfg/stack-analysis/stack-analysis.factor
@@ -14,9 +14,7 @@ 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 ;
+SYMBOL: global-optimization?
 
 : redundant-replace? ( vreg loc -- ? )
     dup state get untranslate-loc n>> 0 <
@@ -63,14 +61,16 @@ UNION: sync-if-back-edge
     ##conditional-branch
     ##compare-imm-branch
     ##dispatch
-    ##loop-entry ;
+    ##loop-entry
+    ##fixnum-overflow ;
 
 : sync-state? ( -- ? )
     basic-block get successors>>
     [ [ predecessors>> ] keep '[ _ back-edge? ] any? ] any? ;
 
 M: sync-if-back-edge visit
-    sync-state? [ sync-state ] when , ;
+    global-optimization? get [ sync-state? [ sync-state ] when ] unless
+    , ;
 
 : eliminate-peek ( dst src -- )
     ! the requested stack location is already in 'src'
@@ -87,31 +87,8 @@ M: ##replace visit
 M: ##copy visit
     [ call-next-method ] [ record-copy ] bi ;
 
-! Instructions that poison the stack state
-UNION: poison-insn
-    ##jump
-    ##return
-    ##callback-return
-    ##fixnum-mul-tail
-    ##fixnum-add-tail
-    ##fixnum-sub-tail ;
-
 M: poison-insn visit call-next-method poison-state ;
 
-! Instructions that kill all live vregs
-UNION: kill-vreg-insn
-    poison-insn
-    ##stack-frame
-    ##call
-    ##prologue
-    ##epilogue
-    ##fixnum-mul
-    ##fixnum-add
-    ##fixnum-sub
-    ##alien-invoke
-    ##alien-indirect
-    ##alien-callback ;
-
 M: kill-vreg-insn visit sync-state , ;
 
 ! Maps basic-blocks to states
@@ -142,21 +119,13 @@ 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 [ add-to-work-list ] each-basic-block
-        process-work-list
+        dup [ visit-block ] each-basic-block
+        global-optimization? get [ work-list get [ visit-block ] slurp-deque ] when
         cfg-changed
     ] with-scope ;
diff --git a/basis/compiler/cfg/stack-analysis/state/state.factor b/basis/compiler/cfg/stack-analysis/state/state.factor
index f701b84763..25fa249853 100644
--- a/basis/compiler/cfg/stack-analysis/state/state.factor
+++ b/basis/compiler/cfg/stack-analysis/state/state.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel accessors namespaces assocs sets math
+USING: kernel accessors namespaces assocs sets math deques
 compiler.cfg.registers ;
 IN: compiler.cfg.stack-analysis.state
 
@@ -47,3 +47,7 @@ M: rs-loc translate-loc [ n>> ] [ rs-height>> ] bi* - <rs-loc> ;
 GENERIC# untranslate-loc 1 ( loc state -- loc' )
 M: ds-loc untranslate-loc [ n>> ] [ ds-height>> ] bi* + <ds-loc> ;
 M: rs-loc untranslate-loc [ n>> ] [ rs-height>> ] bi* + <rs-loc> ;
+
+SYMBOL: work-list
+
+: add-to-work-list ( bb -- ) work-list get push-front ;
diff --git a/basis/compiler/cfg/tco/tco.factor b/basis/compiler/cfg/tco/tco.factor
index 5fa2e1b042..3dbdf148e9 100644
--- a/basis/compiler/cfg/tco/tco.factor
+++ b/basis/compiler/cfg/tco/tco.factor
@@ -2,6 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors combinators.short-circuit kernel math
 namespaces sequences fry combinators
+compiler.utilities
 compiler.cfg
 compiler.cfg.rpo
 compiler.cfg.hats
@@ -19,8 +20,6 @@ IN: compiler.cfg.tco
         [ second ##return? ]
     } 1&& ;
 
-: penultimate ( seq -- elt ) [ length 2 - ] keep nth ;
-
 : tail-call? ( bb -- ? )
     {
         [ instructions>> { [ length 2 >= ] [ last ##branch? ] } 1&& ]
@@ -54,28 +53,11 @@ IN: compiler.cfg.tco
     [ [ cfg get entry>> successors>> first ] dip successors>> push ]
     tri ;
 
-: fixnum-tail-call? ( bb -- ? )
-    instructions>> penultimate
-    { [ ##fixnum-add? ] [ ##fixnum-sub? ] [ ##fixnum-mul? ] } 1|| ;
-
-GENERIC: convert-fixnum-tail-call* ( src1 src2 insn -- insn' )
-
-M: ##fixnum-add convert-fixnum-tail-call* drop \ ##fixnum-add-tail new-insn ;
-M: ##fixnum-sub convert-fixnum-tail-call* drop \ ##fixnum-sub-tail new-insn ;
-M: ##fixnum-mul convert-fixnum-tail-call* drop i i \ ##fixnum-mul-tail new-insn ;
-
-: convert-fixnum-tail-call ( bb -- )
-    [
-        [ src1>> ] [ src2>> ] [ ] tri
-        convert-fixnum-tail-call*
-    ] convert-tail-call ;
-
 : optimize-tail-call ( bb -- )
     dup tail-call? [
         {
             { [ dup loop-tail-call? ] [ convert-loop-tail-call ] }
             { [ dup word-tail-call? ] [ convert-word-tail-call ] }
-            { [ dup fixnum-tail-call? ] [ convert-fixnum-tail-call ] }
             [ drop ]
         } cond
     ] [ drop ] if ;
diff --git a/basis/compiler/cfg/two-operand/two-operand.factor b/basis/compiler/cfg/two-operand/two-operand.factor
index d30a02b0d3..98bbfb9cd0 100644
--- a/basis/compiler/cfg/two-operand/two-operand.factor
+++ b/basis/compiler/cfg/two-operand/two-operand.factor
@@ -44,6 +44,8 @@ M: ##shl-imm convert-two-operand* convert-two-operand/integer ;
 M: ##shr-imm convert-two-operand* convert-two-operand/integer ;
 M: ##sar-imm convert-two-operand* convert-two-operand/integer ;
 
+M: ##fixnum-overflow convert-two-operand* convert-two-operand/integer ;
+
 M: ##add-float convert-two-operand* convert-two-operand/float ;
 M: ##sub-float convert-two-operand* convert-two-operand/float ;
 M: ##mul-float convert-two-operand* convert-two-operand/float ;
diff --git a/basis/compiler/cfg/utilities/utilities.factor b/basis/compiler/cfg/utilities/utilities.factor
index 288fa403dd..9cb8bf26f9 100644
--- a/basis/compiler/cfg/utilities/utilities.factor
+++ b/basis/compiler/cfg/utilities/utilities.factor
@@ -36,6 +36,18 @@ IN: compiler.cfg.utilities
 : emit-primitive ( node -- )
     word>> ##call ##branch begin-basic-block ;
 
+: with-branch ( quot -- final-bb )
+    [
+        begin-basic-block
+        call
+        basic-block get dup [ ##branch ] when
+    ] with-scope ; inline
+
+: emit-conditional ( branches -- )
+    end-basic-block
+    begin-basic-block
+    basic-block get '[ [ _ swap successors>> push ] when* ] each ;
+
 : back-edge? ( from to -- ? )
     [ number>> ] bi@ >= ;
 
diff --git a/basis/compiler/codegen/codegen.factor b/basis/compiler/codegen/codegen.factor
index df6e91aec9..42c6bf45cb 100755
--- a/basis/compiler/codegen/codegen.factor
+++ b/basis/compiler/codegen/codegen.factor
@@ -171,18 +171,12 @@ M: ##sar-imm generate-insn dst/src1/src2 %sar-imm ;
 M: ##not     generate-insn dst/src       %not     ;
 M: ##log2    generate-insn dst/src       %log2    ;
 
-: src1/src2 ( insn -- src1 src2 )
-    [ src1>> register ] [ src2>> register ] bi ; inline
+: label/dst/src1/src2 ( insn -- label dst src1 src2 )
+    [ label>> lookup-label ] [ dst/src1/src2 ] bi ; inline
 
-: src1/src2/temp1/temp2 ( insn -- src1 src2 temp1 temp2 )
-    [ src1/src2 ] [ temp1>> register ] [ temp2>> register ] tri ; inline
-
-M: ##fixnum-add generate-insn src1/src2 %fixnum-add ;
-M: ##fixnum-add-tail generate-insn src1/src2 %fixnum-add-tail ;
-M: ##fixnum-sub generate-insn src1/src2 %fixnum-sub ;
-M: ##fixnum-sub-tail generate-insn src1/src2 %fixnum-sub-tail ;
-M: ##fixnum-mul generate-insn src1/src2/temp1/temp2 %fixnum-mul ;
-M: ##fixnum-mul-tail generate-insn src1/src2/temp1/temp2 %fixnum-mul-tail ;
+M: _fixnum-add generate-insn label/dst/src1/src2 %fixnum-add ;
+M: _fixnum-sub generate-insn label/dst/src1/src2 %fixnum-sub ;
+M: _fixnum-mul generate-insn label/dst/src1/src2 %fixnum-mul ;
 
 : dst/src/temp ( insn -- dst src temp )
     [ dst/src ] [ temp>> register ] bi ; inline
diff --git a/basis/compiler/tree/debugger/debugger.factor b/basis/compiler/tree/debugger/debugger.factor
index 4fc4f4814b..d6906d6348 100644
--- a/basis/compiler/tree/debugger/debugger.factor
+++ b/basis/compiler/tree/debugger/debugger.factor
@@ -1,4 +1,4 @@
-! Copyright (C) 2006, 2008 Slava Pestov.
+! Copyright (C) 2006, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel assocs match fry accessors namespaces make effects
 sequences sequences.private quotations generic macros arrays
@@ -15,7 +15,9 @@ compiler.tree.def-use
 compiler.tree.builder
 compiler.tree.optimizer
 compiler.tree.combinators
-compiler.tree.checker ;
+compiler.tree.checker
+compiler.tree.dead-code
+compiler.tree.modular-arithmetic ;
 FROM: fry => _ ;
 RENAME: _ match => __
 IN: compiler.tree.debugger
@@ -201,8 +203,15 @@ SYMBOL: node-count
 
 : cleaned-up-tree ( quot -- nodes )
     [
-        check-optimizer? on
-        build-tree optimize-tree 
+        build-tree
+        analyze-recursive
+        normalize
+        propagate
+        cleanup
+        compute-def-use
+        remove-dead-code
+        compute-def-use
+        optimize-modular-arithmetic 
     ] with-scope ;
 
 : inlined? ( quot seq/word -- ? )
diff --git a/basis/compiler/tree/finalization/finalization.factor b/basis/compiler/tree/finalization/finalization.factor
index 0e72deb6fa..4c17399c95 100644
--- a/basis/compiler/tree/finalization/finalization.factor
+++ b/basis/compiler/tree/finalization/finalization.factor
@@ -46,6 +46,9 @@ M: predicate finalize-word
         [ drop ]
     } cond ;
 
+M: math-partial finalize-word
+    dup primitive? [ drop ] [ nip cached-expansion ] if ;
+
 M: word finalize-word drop ;
 
 M: #call finalize*
diff --git a/basis/compiler/tree/modular-arithmetic/modular-arithmetic-tests.factor b/basis/compiler/tree/modular-arithmetic/modular-arithmetic-tests.factor
index 7fb1b3d5ac..13555d45f7 100644
--- a/basis/compiler/tree/modular-arithmetic/modular-arithmetic-tests.factor
+++ b/basis/compiler/tree/modular-arithmetic/modular-arithmetic-tests.factor
@@ -4,12 +4,12 @@ IN: compiler.tree.modular-arithmetic.tests
 USING: kernel kernel.private tools.test math math.partial-dispatch
 math.private accessors slots.private sequences strings sbufs
 compiler.tree.builder
-compiler.tree.optimizer
+compiler.tree.normalization
 compiler.tree.debugger
 alien.accessors layouts combinators byte-arrays ;
 
 : test-modular-arithmetic ( quot -- quot' )
-    build-tree optimize-tree nodes>quot ;
+    cleaned-up-tree nodes>quot ;
 
 [ [ >R >fixnum R> >fixnum fixnum+fast ] ]
 [ [ { integer integer } declare + >fixnum ] test-modular-arithmetic ] unit-test
diff --git a/basis/compiler/utilities/utilities.factor b/basis/compiler/utilities/utilities.factor
index ac276b6e41..c21be39adb 100644
--- a/basis/compiler/utilities/utilities.factor
+++ b/basis/compiler/utilities/utilities.factor
@@ -27,4 +27,6 @@ SYMBOL: yield-hook
 yield-hook [ [ ] ] initialize
 
 : alist-max ( alist -- pair )
-    [ ] [ [ [ second ] bi@ > ] most ] map-reduce ;
\ No newline at end of file
+    [ ] [ [ [ second ] bi@ > ] most ] map-reduce ;
+
+: penultimate ( seq -- elt ) [ length 2 - ] keep nth ;
diff --git a/basis/cpu/architecture/architecture.factor b/basis/cpu/architecture/architecture.factor
index 556424f50c..41dd53fa8a 100644
--- a/basis/cpu/architecture/architecture.factor
+++ b/basis/cpu/architecture/architecture.factor
@@ -82,12 +82,9 @@ HOOK: %sar-imm cpu ( dst src1 src2 -- )
 HOOK: %not     cpu ( dst src -- )
 HOOK: %log2    cpu ( dst src -- )
 
-HOOK: %fixnum-add cpu ( src1 src2 -- )
-HOOK: %fixnum-add-tail cpu ( src1 src2 -- )
-HOOK: %fixnum-sub cpu ( src1 src2 -- )
-HOOK: %fixnum-sub-tail cpu ( src1 src2 -- )
-HOOK: %fixnum-mul cpu ( src1 src2 temp1 temp2 -- )
-HOOK: %fixnum-mul-tail cpu ( src1 src2 temp1 temp2 -- )
+HOOK: %fixnum-add cpu ( label dst src1 src2 -- )
+HOOK: %fixnum-sub cpu ( label dst src1 src2 -- )
+HOOK: %fixnum-mul cpu ( label dst src1 src2 -- )
 
 HOOK: %integer>bignum cpu ( dst src temp -- )
 HOOK: %bignum>integer cpu ( dst src temp -- )
diff --git a/basis/cpu/x86/32/32.factor b/basis/cpu/x86/32/32.factor
index 96a99f4d5e..727131aa25 100755
--- a/basis/cpu/x86/32/32.factor
+++ b/basis/cpu/x86/32/32.factor
@@ -51,8 +51,6 @@ M: x86.32 reserved-area-size 0 ;
 
 M: x86.32 %alien-invoke 0 CALL rc-relative rel-dlsym ;
 
-M: x86.32 %alien-invoke-tail 0 JMP rc-relative rel-dlsym ;
-
 M: x86.32 return-struct-in-registers? ( c-type -- ? )
     c-type
     [ return-in-registers?>> ]
diff --git a/basis/cpu/x86/64/64.factor b/basis/cpu/x86/64/64.factor
index 5390d7e0c8..8eb04eb2b5 100644
--- a/basis/cpu/x86/64/64.factor
+++ b/basis/cpu/x86/64/64.factor
@@ -167,11 +167,6 @@ M: x86.64 %alien-invoke
     rc-absolute-cell rel-dlsym
     R11 CALL ;
 
-M: x86.64 %alien-invoke-tail
-    R11 0 MOV
-    rc-absolute-cell rel-dlsym
-    R11 JMP ;
-
 M: x86.64 %prepare-alien-indirect ( -- )
     "unbox_alien" f %alien-invoke
     RBP RAX MOV ;
diff --git a/basis/cpu/x86/x86.factor b/basis/cpu/x86/x86.factor
index bb2ee620e3..bd39549973 100644
--- a/basis/cpu/x86/x86.factor
+++ b/basis/cpu/x86/x86.factor
@@ -129,83 +129,18 @@ M: x86 %log2    BSR ;
 : ?MOV ( dst src -- )
     2dup = [ 2drop ] [ MOV ] if ; inline
 
-:: move>args ( src1 src2 -- )
-    {
-        { [ src1 param-reg-2 = ] [ param-reg-1 src2 ?MOV param-reg-1 param-reg-2 XCHG ] }
-        { [ src1 param-reg-1 = ] [ param-reg-2 src2 ?MOV ] }
-        { [ src2 param-reg-1 = ] [ param-reg-2 src1 ?MOV param-reg-1 param-reg-2 XCHG ] }
-        { [ src2 param-reg-2 = ] [ param-reg-1 src1 ?MOV ] }
-        [
-            param-reg-1 src1 MOV
-            param-reg-2 src2 MOV
-        ]
-    } cond ;
-
-HOOK: %alien-invoke-tail cpu ( func dll -- )
-
-:: overflow-template ( src1 src2 insn inverse func -- )
-    <label> "no-overflow" set
+:: overflow-template ( label dst src1 src2 insn -- )
     src1 src2 insn call
-    ds-reg [] src1 MOV
-    "no-overflow" get JNO
-    src1 src2 inverse call
-    src1 src2 move>args
-    %prepare-alien-invoke
-    func f %alien-invoke
-    "no-overflow" resolve-label ; inline
+    label JO ; inline
 
-:: overflow-template-tail ( src1 src2 insn inverse func -- )
-    <label> "no-overflow" set
-    src1 src2 insn call
-    "no-overflow" get JNO
-    src1 src2 inverse call
-    src1 src2 move>args
-    %prepare-alien-invoke
-    func f %alien-invoke-tail
-    "no-overflow" resolve-label
-    ds-reg [] src1 MOV
-    0 RET ; inline
+M: x86 %fixnum-add ( label dst src1 src2 -- )
+    [ ADD ] overflow-template ;
 
-M: x86 %fixnum-add ( src1 src2 -- )
-    [ ADD ] [ SUB ] "overflow_fixnum_add" overflow-template ;
+M: x86 %fixnum-sub ( label dst src1 src2 -- )
+    [ SUB ] overflow-template ;
 
-M: x86 %fixnum-add-tail ( src1 src2 -- )
-    [ ADD ] [ SUB ] "overflow_fixnum_add" overflow-template-tail ;
-
-M: x86 %fixnum-sub ( src1 src2 -- )
-    [ SUB ] [ ADD ] "overflow_fixnum_subtract" overflow-template ;
-
-M: x86 %fixnum-sub-tail ( src1 src2 -- )
-    [ SUB ] [ ADD ] "overflow_fixnum_subtract" overflow-template-tail ;
-
-M:: x86 %fixnum-mul ( src1 src2 temp1 temp2 -- )
-    "no-overflow" define-label
-    temp1 src1 MOV
-    temp1 tag-bits get SAR
-    src2 temp1 IMUL2
-    ds-reg [] temp1 MOV
-    "no-overflow" get JNO
-    src1 src2 move>args
-    param-reg-1 tag-bits get SAR
-    param-reg-2 tag-bits get SAR
-    %prepare-alien-invoke
-    "overflow_fixnum_multiply" f %alien-invoke
-    "no-overflow" resolve-label ;
-
-M:: x86 %fixnum-mul-tail ( src1 src2 temp1 temp2 -- )
-    "overflow" define-label
-    temp1 src1 MOV
-    temp1 tag-bits get SAR
-    src2 temp1 IMUL2
-    "overflow" get JO
-    ds-reg [] temp1 MOV
-    0 RET
-    "overflow" resolve-label
-    src1 src2 move>args
-    param-reg-1 tag-bits get SAR
-    param-reg-2 tag-bits get SAR
-    %prepare-alien-invoke
-    "overflow_fixnum_multiply" f %alien-invoke-tail ;
+M: x86 %fixnum-mul ( label dst src1 src2 -- )
+    [ swap IMUL2 ] overflow-template ;
 
 : bignum@ ( reg n -- op )
     cells bignum tag-number - [+] ; inline
diff --git a/basis/help/lint/checks/checks.factor b/basis/help/lint/checks/checks.factor
index f8a4e6c15d..56f104a1a1 100644
--- a/basis/help/lint/checks/checks.factor
+++ b/basis/help/lint/checks/checks.factor
@@ -143,7 +143,7 @@ SYMBOL: vocab-articles
     swap '[
         _ elements [
             rest { { } { "" } } member?
-            [ "Empty description" throw ] when
+            [ "Empty $description" simple-lint-error ] when
         ] each
     ] each ;
 
diff --git a/basis/opengl/debug/authors.txt b/basis/opengl/debug/authors.txt
new file mode 100644
index 0000000000..f13c9c1e77
--- /dev/null
+++ b/basis/opengl/debug/authors.txt
@@ -0,0 +1 @@
+Joe Groff
diff --git a/basis/opengl/debug/debug-docs.factor b/basis/opengl/debug/debug-docs.factor
new file mode 100644
index 0000000000..7cb8f9b246
--- /dev/null
+++ b/basis/opengl/debug/debug-docs.factor
@@ -0,0 +1,36 @@
+! (c)2009 Joe Groff bsd license
+USING: help.markup help.syntax multiline tools.continuations ;
+IN: opengl.debug
+
+HELP: G
+{ $description "Makes the OpenGL context associated with " { $link G-world } " active for subsequent OpenGL calls. This is intended to be used from the listener, where interactively entered OpenGL calls can be directed to any window. Note that the Factor UI resets the OpenGL context every time a window is updated, so every code snippet entered in the listener must be prefixed with " { $snippet "G" } " in this use case." }
+{ $examples { $code <" USING: opengl.debug ui ;
+
+[ drop t ] find-window G-world set
+G 0.0 0.0 1.0 1.0 glClearColor
+G GL_COLOR_BUFFER_BIT glClear
+"> } } ;
+
+HELP: F
+{ $description "Flushes the OpenGL context associated with " { $link G-world } ", thereby committing any outstanding drawing operations." } ;
+
+HELP: G-world
+{ $var-description "The world whose OpenGL context is made active by " { $link G } "." } ;
+
+HELP: GB
+{ $description "A shorthand for " { $link gl-break } "." } ;
+
+HELP: gl-break
+{ $description "Suspends the current thread and activates the walker like " { $link break } ", but also preserves the current OpenGL context, saves it to " { $link G-world } " for interactive use through " { $link G } ", and restores the current context when the suspended thread is continued. The shorthand word " { $link POSTPONE: GB } " can also be used." } ;
+
+{ G F G-world POSTPONE: GB gl-break } related-words
+
+ARTICLE: "opengl.debug" "Interactive debugging of OpenGL applications"
+"The " { $vocab-link "opengl.debug" } " vocabulary provides words to assist with interactive debugging of OpenGL applications in the Factor UI."
+{ $subsection G-world }
+{ $subsection G }
+{ $subsection F }
+{ $subsection GB }
+{ $subsection gl-break } ;
+
+ABOUT: "opengl.debug"
diff --git a/basis/opengl/debug/debug.factor b/basis/opengl/debug/debug.factor
new file mode 100644
index 0000000000..7cbdf62346
--- /dev/null
+++ b/basis/opengl/debug/debug.factor
@@ -0,0 +1,23 @@
+! (c)2009 Joe Groff bsd license
+USING: accessors kernel namespaces parser tools.continuations
+ui.backend ui.gadgets.worlds words ;
+IN: opengl.debug
+
+SYMBOL: G-world
+
+: G ( -- )
+    G-world get set-gl-context ;
+
+: F ( -- )
+    G-world get handle>> flush-gl-context ;
+
+: gl-break ( -- )
+    world get dup G-world set-global
+    [ break ] dip
+    set-gl-context ;
+
+<< \ gl-break t "break?" set-word-prop >>
+
+SYNTAX: GB
+    \ gl-break parsed ;
+
diff --git a/basis/opengl/debug/summary.txt b/basis/opengl/debug/summary.txt
new file mode 100644
index 0000000000..3a85f2f3c8
--- /dev/null
+++ b/basis/opengl/debug/summary.txt
@@ -0,0 +1 @@
+Helper words for breaking and interactively manipulating OpenGL applications
diff --git a/basis/ui/gadgets/worlds/worlds-docs.factor b/basis/ui/gadgets/worlds/worlds-docs.factor
index ddaad93b1b..fe662b898c 100755
--- a/basis/ui/gadgets/worlds/worlds-docs.factor
+++ b/basis/ui/gadgets/worlds/worlds-docs.factor
@@ -29,9 +29,6 @@ HELP: set-title
 { $description "Sets the title bar of the native window containing the world." }
 { $notes "This word should not be called directly by user code. Instead, change the " { $snippet "title" } " slot model; see " { $link "models" } "." } ;
 
-HELP: context-world
-{ $var-description "Holds the " { $link world } " whose OpenGL context was most recently made active by " { $link set-gl-context } "." } ;
-
 HELP: set-gl-context
 { $values { "world" world } }
 { $description "Selects an OpenGL context to be the implicit destination for subsequent GL rendering calls. This word is called automatically by the UI before drawing a " { $link world } "." } ;
diff --git a/basis/ui/gadgets/worlds/worlds.factor b/basis/ui/gadgets/worlds/worlds.factor
index 0c59af95d6..91666c4e7a 100755
--- a/basis/ui/gadgets/worlds/worlds.factor
+++ b/basis/ui/gadgets/worlds/worlds.factor
@@ -78,13 +78,11 @@ TUPLE: world-attributes
         '[ f _ [ (>>status-owner) ] [ status>> set-model ] 2bi ] when
     ] [ 2drop ] if ;
 
-SYMBOL: context-world
-
 : window-resource ( resource -- resource )
-    dup context-world get-global window-resources>> push ;
+    dup world get-global window-resources>> push ;
 
 : set-gl-context ( world -- )
-    [ context-world set-global ]
+    [ world set-global ]
     [ handle>> select-gl-context ] bi ;
 
 : with-gl-context ( world quot -- )
diff --git a/extra/alien/inline/syntax/syntax-docs.factor b/extra/alien/inline/syntax/syntax-docs.factor
index 2453d98cf6..0fc5a5140b 100644
--- a/extra/alien/inline/syntax/syntax-docs.factor
+++ b/extra/alien/inline/syntax/syntax-docs.factor
@@ -18,7 +18,7 @@ HELP: C-FUNCTION:
 { $description "Appends a function to the C library in scope and defines an FFI word that calls it." }
 { $examples
   { $example
-    "USING: alien.inline prettyprint ;"
+    "USING: alien.inline.syntax prettyprint ;"
     "IN: cmath.ffi"
     ""
     "C-LIBRARY: cmathlib"
@@ -44,7 +44,7 @@ HELP: C-LIBRARY:
 { $description "Starts a new C library scope. Other " { $snippet "alien.inline" } " syntax can be used after this word." }
 { $examples
   { $example
-    "USING: alien.inline ;"
+    "USING: alien.inline.syntax ;"
     "IN: rectangle.ffi"
     ""
     "C-LIBRARY: rectlib"
diff --git a/extra/alien/marshall/syntax/syntax-docs.factor b/extra/alien/marshall/syntax/syntax-docs.factor
index c432ec2ad5..401934e736 100644
--- a/extra/alien/marshall/syntax/syntax-docs.factor
+++ b/extra/alien/marshall/syntax/syntax-docs.factor
@@ -12,7 +12,7 @@ HELP: CM-FUNCTION:
 }
 { $examples
   { $example
-    "USING: alien.inline alien.marshall.syntax prettyprint ;"
+    "USING: alien.inline.syntax alien.marshall.syntax prettyprint ;"
     "IN: example"
     ""
     "C-LIBRARY: exlib"
@@ -28,10 +28,8 @@ HELP: CM-FUNCTION:
     ""
     ";C-LIBRARY"
     ""
-    "8 5 0 0 sum_diff .s"
-    "\"sum 13, diff 3\""
-    "13"
-    "3"
+    "8 5 0 0 sum_diff . . ."
+    "3\n13\n\"sum 13, diff 3\""
   }
 }
 { $see-also define-c-marshalled POSTPONE: C-FUNCTION: POSTPONE: M-FUNCTION: } ;
diff --git a/extra/alien/marshall/syntax/syntax-tests.factor b/extra/alien/marshall/syntax/syntax-tests.factor
index 6ea6488167..3945924a57 100644
--- a/extra/alien/marshall/syntax/syntax-tests.factor
+++ b/extra/alien/marshall/syntax/syntax-tests.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2009 Jeremy Hughes.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: alien.inline alien.marshall.syntax destructors
+USING: alien.inline.syntax alien.marshall.syntax destructors
 tools.test accessors kernel ;
 IN: alien.marshall.syntax.tests
 
diff --git a/extra/benchmark/benchmark.factor b/extra/benchmark/benchmark.factor
index ca71e22e9f..23809f2744 100755
--- a/extra/benchmark/benchmark.factor
+++ b/extra/benchmark/benchmark.factor
@@ -2,7 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel vocabs vocabs.loader tools.time vocabs.hierarchy
 arrays assocs io.styles io help.markup prettyprint sequences
-continuations debugger math namespaces memory ;
+continuations debugger math namespaces memory fry ;
 IN: benchmark
 
 <PRIVATE
@@ -12,9 +12,12 @@ SYMBOL: errors
 
 PRIVATE>
 
+: (run-benchmark) ( vocab -- time )
+    [ 5 ] dip '[ gc [ _ run ] benchmark ] replicate infimum ;
+
 : run-benchmark ( vocab -- )
     [ "=== " write print flush ] [
-        [ [ require ] [ gc [ run ] benchmark ] [ ] tri timings ]
+        [ [ require ] [ (run-benchmark) ] [ ] tri timings ]
         [ swap errors ]
         recover get set-at
     ] bi ;
@@ -24,6 +27,7 @@ PRIVATE>
         V{ } clone timings set
         V{ } clone errors set
         "benchmark" child-vocab-names
+        [ find-vocab-root ] filter
         [ run-benchmark ] each
         timings get
         errors get