Add phi elimination pass

[factor.git] / basis / compiler / cfg / phi-elimination / phi-elimination.factor

diff --git a/basis/compiler/cfg/phi-elimination/phi-elimination.factor b/basis/compiler/cfg/phi-elimination/phi-elimination.factor
new file mode 100644 (file)
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--- /dev/null
+++ b/basis/compiler/cfg/phi-elimination/phi-elimination.factor
@@ -0,0 +1,21 @@
+! Copyright (C) 2009 Slava Pestov.
+! See http://factorcode.org/license.txt for BSD license.
+USING: accessors compiler.cfg compiler.cfg.instructions fry
+kernel sequences ;
+IN: compiler.cfg.phi-elimination
+
+: insert-copy ( predecessor input output -- )
+    '[ _ _ swap ##copy ] add-instructions ;
+
+: eliminate-phi ( bb ##phi -- )
+    [ predecessors>> ] [ [ inputs>> ] [ dst>> ] bi ] bi*
+    '[ _ insert-copy ] 2each ;
+
+: eliminate-phi-step ( bb -- )
+    dup [
+        [ ##phi? ] partition
+        [ [ eliminate-phi ] with each ] dip
+    ] change-instructions drop ;
+
+: eliminate-phis ( rpo -- )
+    [ eliminate-phi-step ] each ;
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