kickc/src/main/java/dk/camelot64/kickc/passes/Pass1CallVoidReturns.java

package dk.camelot64.kickc.passes;

import dk.camelot64.kickc.model.*;
import dk.camelot64.kickc.model.statements.Statement;
import dk.camelot64.kickc.model.statements.StatementCall;
import dk.camelot64.kickc.model.symbols.Procedure;
import dk.camelot64.kickc.model.symbols.Variable;
import dk.camelot64.kickc.model.types.SymbolType;
import dk.camelot64.kickc.model.values.LValue;
import dk.camelot64.kickc.model.values.ProcedureRef;
import dk.camelot64.kickc.model.values.VariableRef;

import java.util.Collection;

/** Remove temporary variables assigned any void return value */
public class Pass1CallVoidReturns extends Pass2SsaOptimization {

   public Pass1CallVoidReturns(Program program) {
      super(program);
   }

   @Override
   public boolean step() {
      new PassNStatementIndices(getProgram()).execute();
      getProgram().clearVariableReferenceInfos();
      getProgram().clearControlFlowBlockSuccessorClosure();
      VariableReferenceInfos referenceInfos = getProgram().getVariableReferenceInfos();

      for(var statement : getGraph().getAllStatements()) {
         if (statement instanceof StatementCall) {
            final ProcedureRef procedureRef = ((StatementCall) statement).getProcedure();
            final Procedure procedure = getProgramScope().getProcedure(procedureRef);
            if (SymbolType.VOID.equals(procedure.getReturnType())) {
               // Found a call to a VOID returning procedure
               final LValue lValue = ((StatementCall) statement).getlValue();
               if (lValue instanceof VariableRef) {
                  VariableRef tmpVar = (VariableRef) lValue;
                  final Collection<Integer> usages = referenceInfos.getVarUseStatements(tmpVar);
                  if (usages.size() > 0) {
                     final Integer usageIdx = usages.iterator().next();
                     final Statement usage = getProgram().getStatementInfos()
                         .getStatement(usageIdx);
                     throw new CompileError(
                         "Function " + procedure.getLocalName() + " does not return a value! ",
                         usage);
                  } else {
                     // Delete the temporary variable
                     final Variable var = getProgramScope().getVar(tmpVar);
                     var.getScope().remove(var);
                     // And remove the lValue
                     ((StatementCall) statement).setlValue(null);
                     if (getLog().isVerbosePass1CreateSsa()) {
                        getLog().append("Removing LValue from call to function returning void");
                     }
                  }
               }
            }
         }
      }
      getProgram().clearStatementIndices();
      getProgram().clearVariableReferenceInfos();
      getProgram().clearControlFlowBlockSuccessorClosure();
      return false;
   }

}