diff --git a/basis/compiler/cfg/coalescing/coalescing.factor b/basis/compiler/cfg/coalescing/coalescing.factor
index 28528068c2..a9637088a3 100644
--- a/basis/compiler/cfg/coalescing/coalescing.factor
+++ b/basis/compiler/cfg/coalescing/coalescing.factor
@@ -7,10 +7,12 @@ compiler.cfg.def-use
 compiler.cfg.utilities
 compiler.cfg.dominance
 compiler.cfg.instructions
+compiler.cfg.critical-edges
 compiler.cfg.coalescing.state
 compiler.cfg.coalescing.forest
 compiler.cfg.coalescing.copies
 compiler.cfg.coalescing.renaming
+compiler.cfg.coalescing.live-ranges
 compiler.cfg.coalescing.process-blocks ;
 IN: compiler.cfg.coalescing
 
@@ -49,9 +51,11 @@ SYMBOL: seen
 
 : coalesce ( cfg -- cfg' )
     init-coalescing
+    dup split-critical-edges
     dup compute-def-use
     dup compute-dominance
     dup compute-dfs
+    dup compute-live-ranges
     dup process-blocks
     break-interferences
     dup perform-renaming
diff --git a/basis/compiler/cfg/coalescing/copies/copies.factor b/basis/compiler/cfg/coalescing/copies/copies.factor
index ab1c514c96..5df2684f72 100644
--- a/basis/compiler/cfg/coalescing/copies/copies.factor
+++ b/basis/compiler/cfg/coalescing/copies/copies.factor
@@ -7,7 +7,7 @@ IN: compiler.cfg.coalescing.copies
 : compute-copies ( assoc -- assoc' )
     dup assoc-size <hashtable> [
         '[
-            [ _ 2dup key? [ "OOPS" throw ] [ set-at ] if ] with each
+            [ 2dup eq? [ 2drop ] [ _ 2dup key? [ "OOPS" throw ] [ set-at ] if ] if ] with each
         ] assoc-each
     ] keep ;
 
diff --git a/basis/compiler/cfg/coalescing/interference/interference.factor b/basis/compiler/cfg/coalescing/interference/interference.factor
index 9fdf06bcb4..ff5e6319e6 100644
--- a/basis/compiler/cfg/coalescing/interference/interference.factor
+++ b/basis/compiler/cfg/coalescing/interference/interference.factor
@@ -2,48 +2,32 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors assocs combinators combinators.short-circuit
 kernel math namespaces sequences locals compiler.cfg.def-use
-compiler.cfg.liveness compiler.cfg.dominance ;
+compiler.cfg.dominance compiler.cfg.coalescing.live-ranges ;
 IN: compiler.cfg.coalescing.interference
 
-! Local interference testing. Requires live-out information
 <PRIVATE
 
-SYMBOLS: def-index kill-index ;
-
-: compute-local-live-ranges ( bb -- )
-    H{ } clone def-index set
-    H{ } clone kill-index set
-    [
-        instructions>> [
-            [ swap defs-vregs [ def-index get set-at ] with each ]
-            [ swap uses-vregs [ kill-index get set-at ] with each ]
-            2bi
-        ] each-index
-    ]
-    [ live-out keys [ [ 1/0. ] dip kill-index get set-at ] each ]
-    bi ;
-
-: kill-after-def? ( vreg1 vreg2 -- ? )
+: kill-after-def? ( vreg1 vreg2 bb -- ? )
     ! If first register is killed after second one is defined, they interfere
-    [ kill-index get at ] [ def-index get at ] bi* >= ;
+    [ kill-index ] [ def-index ] bi-curry bi* >= ;
 
 : interferes-same-block? ( vreg1 vreg2 bb1 bb2 -- ? )
     ! If both are defined in the same basic block, they interfere if their
     ! local live ranges intersect.
-    drop compute-local-live-ranges
-    { [ kill-after-def? ] [ swap kill-after-def? ] } 2|| ;
+    drop
+    { [ kill-after-def? ] [ swapd kill-after-def? ] } 3|| ;
 
 : interferes-first-dominates? ( vreg1 vreg2 bb1 bb2 -- ? )
     ! If vreg1 dominates vreg2, then they interfere if vreg2's definition
     ! occurs before vreg1 is killed.
-    nip compute-local-live-ranges
+    nip
     kill-after-def? ;
 
 : interferes-second-dominates? ( vreg1 vreg2 bb1 bb2 -- ? )
     ! If vreg2 dominates vreg1, then they interfere if vreg1's definition
     ! occurs before vreg2 is killed.
-    drop compute-local-live-ranges
-    swap kill-after-def? ;
+    drop
+    swapd kill-after-def? ;
 
 PRIVATE>
 
diff --git a/basis/compiler/cfg/coalescing/live-ranges/live-ranges.factor b/basis/compiler/cfg/coalescing/live-ranges/live-ranges.factor
new file mode 100644
index 0000000000..f35a752ea6
--- /dev/null
+++ b/basis/compiler/cfg/coalescing/live-ranges/live-ranges.factor
@@ -0,0 +1,42 @@
+! Copyright (C) 2009 Slava Pestov.
+! See http://factorcode.org/license.txt for BSD license.
+USING: accessors assocs fry kernel namespaces sequences
+compiler.cfg.def-use compiler.cfg.instructions
+compiler.cfg.liveness compiler.cfg.rpo ;
+IN: compiler.cfg.coalescing.live-ranges
+
+! Live ranges for interference testing
+
+<PRIVATE
+
+SYMBOLS: local-def-indices local-kill-indices ;
+
+: record-defs ( n vregs -- )
+    local-def-indices get '[ _ set-at ] with each ;
+
+: record-uses ( n vregs -- )
+    local-kill-indices get '[ _ set-at ] with each ;
+
+: visit-insn ( insn n -- )
+    [ swap defs-vregs record-defs ]
+    [ swap uses-vregs record-uses ]
+    [ over def-is-use-insn? [ swap defs-vregs record-uses ] [ 2drop ] if ]
+    2tri ;
+
+SYMBOLS: def-indices kill-indices ;
+
+: compute-local-live-ranges ( bb -- )
+    H{ } clone local-def-indices set
+    H{ } clone local-kill-indices set
+    instructions>> [ visit-insn ] each-index ;
+
+PRIVATE>
+
+: compute-live-ranges ( cfg -- )
+    [ compute-local-live-ranges ] each-basic-block ;
+
+: def-index ( vreg bb -- n )
+    def-indices get at at ;
+
+: kill-index ( vreg bb -- n )
+    2dup live-out key? [ 2drop 1/0. ] [ kill-indices get at at ] if ;
diff --git a/basis/compiler/cfg/critical-edges/critical-edges.factor b/basis/compiler/cfg/critical-edges/critical-edges.factor
new file mode 100644
index 0000000000..92b4f801d6
--- /dev/null
+++ b/basis/compiler/cfg/critical-edges/critical-edges.factor
@@ -0,0 +1,19 @@
+! Copyright (C) 2009 Slava Pestov.
+! See http://factorcode.org/license.txt for BSD license.
+USING: kernel math accessors sequences
+compiler.cfg compiler.cfg.rpo compiler.cfg.utilities ;
+IN: compiler.cfg.critical-edges
+
+: critical-edge? ( from to -- ? )
+    [ successors>> length 1 > ] [ predecessors>> length 1 > ] bi* and ;
+
+: split-critical-edge ( from to -- )
+    f <simple-block> insert-basic-block ;
+
+: split-critical-edges ( cfg -- )
+    [
+        dup successors>> [
+            2dup critical-edge?
+            [ split-critical-edge ] [ 2drop ] if
+        ] with each
+    ] each-basic-block ;
\ No newline at end of file
diff --git a/basis/compiler/cfg/instructions/instructions.factor b/basis/compiler/cfg/instructions/instructions.factor
index 07ebcc3ba9..066d20ddec 100644
--- a/basis/compiler/cfg/instructions/instructions.factor
+++ b/basis/compiler/cfg/instructions/instructions.factor
@@ -251,3 +251,10 @@ UNION: kill-vreg-insn
     ##alien-invoke
     ##alien-indirect
     ##alien-callback ;
+
+! Instructions that have complex expansions and require that the
+! output registers are not equal to any of the input registers
+UNION: def-is-use-insn
+    ##integer>bignum
+    ##bignum>integer
+    ##unbox-any-c-ptr ;
\ No newline at end of file