compiler.cfg.coalescing: Only run if CFG has ##phi nodes, fix interference for case where value is not used in a block and is not live-in, forgot to run liveness analysis first

basis/compiler/cfg/coalescing/coalescing.factor

@@ -7,6 +7,7 @@ compiler.cfg.def-use
 compiler.cfg.utilities
 compiler.cfg.dominance
 compiler.cfg.instructions
+compiler.cfg.liveness.ssa
 compiler.cfg.critical-edges
 compiler.cfg.coalescing.state
 compiler.cfg.coalescing.forest
@@ -36,10 +37,7 @@ SYMBOL: seen
     V{ } clone seen set
     renaming-sets get [| dst assoc |
         assoc [| src bb |
-            src seen get key?
-            [ dst assoc src bb visit-renaming ]
-            [ src seen get conjoin ]
-            if
+            dst assoc src bb visit-renaming
         ] assoc-each
     ] assoc-each ;
 
@@ -50,14 +48,17 @@ SYMBOL: seen
     [ [ remove-phis-from-block ] if-has-phis ] each-basic-block ;
 
 : 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
-    insert-copies
-    dup remove-phis ;
+    dup cfg-has-phis? [
+        init-coalescing
+        compute-ssa-live-sets
+        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
+        insert-copies
+        dup remove-phis
+    ] when ;

basis/compiler/cfg/coalescing/interference/interference.factor

@@ -8,8 +8,12 @@ IN: compiler.cfg.coalescing.interference
 <PRIVATE
 
 : kill-after-def? ( vreg1 vreg2 bb -- ? )
-    ! If first register is killed after second one is defined, they interfere
-    [ kill-index ] [ def-index ] bi-curry bi* >= ;
+    ! If first register is used after second one is defined, they interfere.
+    ! If they are used in the same instruction, no interference. If the
+    ! instruction is a def-is-use-insn, then there will be a use at +1
+    ! (instructions are 2 apart) and so outputs will interfere with
+    ! inputs.
+    [ 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

basis/compiler/cfg/coalescing/live-ranges/live-ranges.factor

@@ -1,6 +1,6 @@
 ! Copyright (C) 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors assocs fry kernel namespaces sequences
+USING: accessors assocs fry kernel namespaces sequences math
 compiler.cfg.def-use compiler.cfg.instructions
 compiler.cfg.liveness compiler.cfg.rpo ;
 IN: compiler.cfg.coalescing.live-ranges
@@ -18,9 +18,15 @@ SYMBOLS: local-def-indices local-kill-indices ;
     local-kill-indices get '[ _ set-at ] with each ;
 
 : visit-insn ( insn n -- )
+    ! Instructions are numbered 2 apart. If the instruction requires
+    ! that outputs are in different registers than the inputs, then
+    ! a use will be registered for every output immediately after
+    ! this instruction and before the next one, ensuring that outputs
+    ! interfere with inputs.
+    2 *
     [ swap defs-vregs record-defs ]
     [ swap uses-vregs record-uses ]
-    [ over def-is-use-insn? [ swap defs-vregs record-uses ] [ 2drop ] if ]
+    [ over def-is-use-insn? [ 1 + swap defs-vregs record-uses ] [ 2drop ] if ]
     2tri ;
 
 SYMBOLS: def-indices kill-indices ;
@@ -28,15 +34,27 @@ 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 ;
+    [ instructions>> [ visit-insn ] each-index ]
+    [ [ local-def-indices get ] dip def-indices get set-at ]
+    [ [ local-kill-indices get ] dip kill-indices get set-at ]
+    tri ;
 
 PRIVATE>
 
 : compute-live-ranges ( cfg -- )
+    H{ } clone def-indices set
+    H{ } clone kill-indices set
     [ compute-local-live-ranges ] each-basic-block ;
 
 : def-index ( vreg bb -- n )
     def-indices get at at ;
 
+ERROR: bad-kill-index vreg bb ;
+
 : kill-index ( vreg bb -- n )
-    2dup live-out key? [ 2drop 1/0. ] [ kill-indices get at at ] if ;
+    2dup live-out key? [ 2drop 1/0. ] [
+        2dup kill-indices get at at* [ 2nip ] [
+            drop 2dup live-in key?
+            [ bad-kill-index ] [ 2drop -1/0. ] if
+        ] if
+    ] if ;

basis/compiler/cfg/utilities/utilities.factor

@@ -48,5 +48,8 @@ SYMBOL: visited
 : has-phis? ( bb -- ? )
     instructions>> first ##phi? ;
 
+: cfg-has-phis? ( cfg -- )
+    post-order [ has-phis? ] any? ;
+
 : if-has-phis ( bb quot: ( bb -- ) -- )
     [ dup has-phis? ] dip [ drop ] if ; inline