Nice/src/bossa/syntax typecheck.nice,1.127,1.128

Update of /cvsroot/nice/Nice/src/bossa/syntax
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv11965/src/bossa/syntax

Modified Files:
	typecheck.nice 
Log Message:
RFE 681385 implemented.

Index: typecheck.nice
===================================================================
RCS file: /cvsroot/nice/Nice/src/bossa/syntax/typecheck.nice,v
retrieving revision 1.127
retrieving revision 1.128
diff -C2 -d -r1.127 -r1.128
*** typecheck.nice	7 Mar 2005 17:10:50 -0000	1.127
--- typecheck.nice	7 Mar 2005 20:52:53 -0000	1.128
***************
*** 54,58 ****
      
      // RFE 681385
-     // To debug in jdb use "stop at bossa.syntax.fun:LINE".
      if( variable != null ){
        let valueType = e.value.type, toType = to.type, varType = variable.type;
--- 54,57 ----
***************
*** 534,537 ****
--- 533,557 ----
  }
  
+ /**
+  * Collect inference information from branches,
+  * so that it can be propagated outwards.
+  */
+ class DeepMemoryRec {
+   MonoSymbol variable;
+   mlsub.typing.Monotype type;
+   toString() = "(" variable "," type ")";
+ }
+ var Stack<Stack<DeepMemoryRec>> deepMemory = new Stack();
+ equals( DeepMemoryRec a, DeepMemoryRec b ) = a.variable == b.variable;
+ 
+ void populateDeepMemory(MonoSymbol variable, mlsub.typing.Monotype type)
+ {
+   if(deepMemory.size() == 0) return;
+   let branch = deepMemory.peek();
+   let rec = new DeepMemoryRec(variable: variable, type: type);
+   while( branch.removeElement( rec ) ){}
+   branch.push(rec);
+ }
+ 
  typecheck(IfExp e)
  {
***************
*** 546,549 ****
--- 566,573 ----
    enterBlock();
  
+   let Stack<DeepMemoryRec> ifBranchInference = new Stack();
+   let Stack<DeepMemoryRec> elseBranchInference = new Stack();
+   deepMemory.push( elseBranchInference );
+ 
    try{
      ?List<MonoSymbol> notNullInThen, notNullInElse;
***************
*** 551,554 ****
--- 575,580 ----
      ?List<(MonoSymbol, mlsub.typing.Monotype)> instanceofInElse;
  
+     deepMemory.push( ifBranchInference );
+ 
      try {
        (notNullInThen, notNullInElse) = nullnessInfo(condition);
***************
*** 576,579 ****
--- 602,606 ----
        // which is good when calling the compiler repeatedly from the same JVM.
        enterElse();
+       let got = deepMemory.pop(); assert got == ifBranchInference;
      }
  
***************
*** 598,601 ****
--- 625,629 ----
    finally{
      exitIf();
+     let got = deepMemory.pop(); assert got == elseBranchInference;
    }
  
***************
*** 605,608 ****
--- 633,656 ----
         "\nthen: " + thenExp.getType() +
         "\nelse: " + elseExp.getType());
+ 
+   // Check if we can propagate some of the type inference information outwards.
+   if(ifBranchInference.size() != 0 || elseBranchInference.size() != 0)
+     ifPropagation(e, ifBranchInference, elseBranchInference);
+ }
+ 
+ void ifPropagation(IfExp e, Stack<DeepMemoryRec> ifBranchInference, Stack<DeepMemoryRec> elseBranchInference){
+   let condition = e.condition;
+   if(! (condition instanceof bossa.syntax.CallExp) || ! condition.isCallTo("==")) return;
+   if(condition.arguments.size() != 2) return;
+   let argle = condition.arguments.get(0); let leNull = argle.value.isNull();
+   let argri = condition.arguments.get(1); let riNull = argri.value.isNull();
+   if((leNull || riNull) && leNull != riNull){
+     if(e.elseExp instanceof bossa.syntax.VoidConstantExp && ifBranchInference.size() != 0){
+       let arg = leNull ? argri.value : argle.value;
+       let variable = localVariable( arg ); if( null == variable ) return;
+       for(rec : ifBranchInference) if(variable == rec.variable)
+         variable.setVarType( rec.type, otherBranch: variable.type, out: variable.type );
+     }
+   }
  }
  
***************
*** 622,625 ****
--- 670,674 ----
  {
    variable.type = now;
+   populateDeepMemory( variable, now );
    if (overrideOut != null)
      {



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