* interp/g-opt.boot (removeJunk!): Rename from removeSeq!

	(cancelScopeLeave!): New.
	(inlineLocals!): Tidy.
	(optimize!): Run cancelScopeLeave! right after removeJunk!.

1 files changed, 19 insertions, 6 deletions

diff --git a/src/interp/g-opt.boot b/src/interp/g-opt.boot
index 20b1b962..851e7eb6 100644
--- a/src/interp/g-opt.boot
+++ b/src/interp/g-opt.boot
@@ -214,9 +214,12 @@ reduceXLAM! x == walkWith!(x,function f) where
      resetTo(x,doInlineCall(args,y.absParms,copyTree y.absBody))
     x
 
-++ Splice in all %seq subforms, remove throw away expressions,
-++ and remove unnecessary %seq boxes around singleton expressions.
-removeSeq! x == walkWith!(x,function f) where
+++ Remove throw-away expressions, inline one-time temporaries
+++ abstracting conditionals (generated by the parser) and remove
+++ unnecessary %seq boxes around singleton expressions.
+++ NOTES: this transformation must be run before any grouping
+++        of intermediate result bindings.
+removeJunk! x == walkWith!(x,function f) where
   f x ==
     x is ['%seq,:.] =>
       x.args := g x.args
@@ -227,6 +230,8 @@ removeSeq! x == walkWith!(x,function f) where
     xs = nil => nil
     x := first xs
     x is "/throwAway" => g rest xs          -- skip garbages
+    x is ['%LET,y,u] and gensym? y and numOfOccurencesOf(y,rest xs) = 1 =>
+      g substitute!(u,y,rest xs)
     x is ['%seq,:.] =>                      -- splice sub-sequences
       ys := x.args =>
         lastNode(ys).rest := rest xs
@@ -239,12 +244,12 @@ removeSeq! x == walkWith!(x,function f) where
 
 inlineLocals! x == walkWith!(x,function f) where
   f x ==
-    x is ['%bind,[[y,a]],z] and gensym? y and numOfOccurencesOf(y,z) = 1 =>
-      resetTo(x,f substitute!(a,y,z))
     x is ['%bind,inits,:.] =>
       kept := nil
       while inits is [u,:inits] repeat
         [y,z] := u
+        gensym? y and numOfOccurencesOf(y,x.absBody) = 1 =>
+          x.absBody := substitute!(z,y,x.absBody)
         usedSymbol?(y,z) or usedSymbol?(y,inits) => kept := [u,:kept]
         or/[usedSymbol?(v,z) for [v,.] in kept] => kept := [u,:kept]
         canInlineVarDefinition(y,z,x.absBody) =>
@@ -314,6 +319,14 @@ spliceSeq! x == walkWith!(x,function f) where
       x.args := spliceSeqArgs x.args
     x
 
+++ Remove superfluous cancel/scope pairs exposed by running
+++ removeJunk!.
+cancelScopeLeave! x == walkWith!(x,function f) where
+  f x ==
+    x is ['%scope,g,['%leave,=g,y]] and hasNoLeave?(y,g) =>
+      resetTo(x,f y)
+    x
+
 ++ Transform an intermediate form (output of the elaborator) to
 ++ a lower intermediate form, applying several transformations
 ++ generaly intended to improve quality and efficiency.
@@ -321,7 +334,7 @@ optimize! x ==
   x := spliceSeq! packWhen! transformIF! x
   changeVariableDefinitionToStore(x,nil)
   simplifyVMForm spliceSeq! packWhen! inlineLocals!
-    groupTranscients! removeSeq! reduceXLAM! x
+    groupTranscients! cancelScopeLeave! removeJunk! reduceXLAM! x
 
 ++ A non-mutating version of `optimize!'.
 optimize x ==