bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/internal/codegen/ssa/exits/If.java

   1 package org.simantics.scl.compiler.internal.codegen.ssa.exits;
   2
   3 import java.util.ArrayList;
   4
   5 import org.objectweb.asm.Label;
   6 import org.simantics.scl.compiler.common.exceptions.InternalCompilerError;
   7 import org.simantics.scl.compiler.constants.BooleanConstant;
   8 import org.simantics.scl.compiler.internal.codegen.continuations.Cont;
   9 import org.simantics.scl.compiler.internal.codegen.continuations.ContRef;
  10 import org.simantics.scl.compiler.internal.codegen.references.Val;
  11 import org.simantics.scl.compiler.internal.codegen.references.ValRef;
  12 import org.simantics.scl.compiler.internal.codegen.ssa.SSABlock;
  13 import org.simantics.scl.compiler.internal.codegen.ssa.SSAExit;
  14 import org.simantics.scl.compiler.internal.codegen.ssa.SSAFunction;
  15 import org.simantics.scl.compiler.internal.codegen.ssa.binders.ValRefBinder;
  16 import org.simantics.scl.compiler.internal.codegen.utils.CopyContext;
  17 import org.simantics.scl.compiler.internal.codegen.utils.MethodBuilder;
  18 import org.simantics.scl.compiler.internal.codegen.utils.PrintingContext;
  19 import org.simantics.scl.compiler.internal.codegen.utils.SSASimplificationContext;
  20 import org.simantics.scl.compiler.internal.codegen.utils.SSAValidationContext;
  21 import org.simantics.scl.compiler.types.TVar;
  22 import org.simantics.scl.compiler.types.Type;
  23 import org.simantics.scl.compiler.types.Types;
  24
  25 public class If extends SSAExit implements ValRefBinder {
  26     private ValRef condition;
  27     private ContRef thenTarget;
  28     private ContRef elseTarget;
  29
  30     public If(ValRef condition, ContRef thenTarget, ContRef elseTarget) {
  31         setCondition(condition);
  32         setThenTarget(thenTarget);
  33         setElseTarget(elseTarget);
  34     }
  35
  36     public void setCondition(ValRef condition) {
  37         this.condition = condition;
  38         condition.setParent(this);
  39     }
  40
  41     public void setThenTarget(ContRef thenTarget) {
  42         this.thenTarget = thenTarget;
  43         thenTarget.setParent(this);
  44     }
  45
  46     public void setElseTarget(ContRef elseTarget) {
  47         this.elseTarget = elseTarget;
  48         elseTarget.setParent(this);
  49     }
  50
  51     @Override
  52     public void generateCode(MethodBuilder mb) {
  53         mb.push(condition.getBinding(), Types.BOOLEAN);
  54         Label elseLabel = mb.getLabel(elseTarget.getBinding());
  55         mb.ifZeroComparisonBranch(elseLabel, "==");
  56         mb.jump(thenTarget.getBinding());
  57         mb.ensureExists(elseTarget.getBinding());
  58     }
  59
  60     @Override
  61     public void toString(PrintingContext context) {
  62         context.append("if ");
  63         context.append(condition);
  64         context.append(" then ");
  65         {
  66             Cont thenCont = thenTarget.getBinding();
  67             if(thenCont instanceof SSABlock) {
  68                 SSABlock thenBlock = (SSABlock)thenCont;
  69                 if(thenCont.hasMoreThanOneOccurences()) {
  70                     context.append(thenCont);
  71                     context.addBlock(thenBlock);
  72                     context.append(' ');
  73                 }
  74                 else {
  75                     context.append('\n');
  76                     thenBlock.bodyToString(context);
  77                     context.indentation();
  78                 }
  79             }
  80             else {
  81                 context.append(thenCont);
  82                 context.append(' ');
  83             }
  84         }
  85         context.append("else ");
  86         {
  87             Cont elseCont = elseTarget.getBinding();
  88             if(elseCont instanceof SSABlock) {
  89                 SSABlock elseBlock = (SSABlock)elseCont;
  90                 if(elseCont.hasMoreThanOneOccurences()) {
  91                     context.append(elseCont);
  92                     context.addBlock(elseBlock);
  93                     context.append('\n');
  94                 }
  95                 else {
  96                     context.append('\n');
  97                     elseBlock.bodyToString(context);
  98                 }
  99             }
 100             else {
 101                 context.append(elseCont);
 102                 context.append('\n');
 103             }
 104         }
 105     }
 106
 107     @Override
 108     public void validate(SSAValidationContext context) {
 109         context.validate(condition);
 110         context.validate(elseTarget);
 111         context.validate(thenTarget);
 112         if(condition.getParent() != this)
 113             throw new InternalCompilerError();
 114         if(elseTarget.getParent() != this)
 115             throw new InternalCompilerError();
 116         if(thenTarget.getParent() != this)
 117             throw new InternalCompilerError();
 118         context.assertEquals(this, condition.getType(), Types.BOOLEAN);
 119         context.assertEquals(elseTarget.getBinding().getArity(), 0);
 120         context.assertEquals(thenTarget.getBinding().getArity(), 0);
 121     }
 122
 123     @Override
 124     public void destroy() {
 125         condition.remove();
 126         elseTarget.remove();
 127         thenTarget.remove();
 128     }
 129
 130     @Override
 131     public SSAExit copy(CopyContext context) {
 132         return new If(context.copy(condition),
 133                 context.copy(thenTarget),
 134                 context.copy(elseTarget));
 135     }
 136
 137     @Override
 138     public void replace(TVar[] vars, Type[] replacements) {
 139         condition.replace(vars, replacements);
 140     }
 141
 142     @Override
 143     public void simplify(SSASimplificationContext context) {
 144         Val cond = condition.getBinding();
 145         if(cond instanceof BooleanConstant) {
 146             SSAExit newExit;
 147             if(((BooleanConstant) cond).getValue()) {
 148                 newExit = new Jump(thenTarget);
 149                 elseTarget.remove();
 150             }
 151             else {
 152                 newExit = new Jump(elseTarget);
 153                 thenTarget.remove();
 154             }
 155             condition.remove();
 156             getParent().setExit(newExit);
 157             context.markModified("beta-if");
 158         }
 159         else if(thenTarget.getBinding() == elseTarget.getBinding()) {
 160             elseTarget.remove();
 161             condition.remove();
 162             getParent().setExit(new Jump(thenTarget));
 163             context.markModified("equal-branches-if");
 164         }
 165     }
 166
 167     @Override
 168     public void collectFreeVariables(SSAFunction function,
 169             ArrayList<ValRef> vars) {
 170         condition.collectFreeVariables(function, vars);
 171     }
 172
 173     @Override
 174     public Cont addParametersInFrontOf(ContRef contRef, Val[] newParameters, Val[] oldParameters,
 175             Cont proxy) {
 176         if(proxy == null)
 177             proxy = contRef.getBinding().createProxy(getParent().getParent(), newParameters, oldParameters);
 178         ContRef proxyRef = proxy.createOccurrence();
 179         if(thenTarget == contRef)
 180             setThenTarget(proxyRef);
 181         else
 182             setElseTarget(proxyRef);
 183         return proxy;
 184     }
 185
 186     @Override
 187     public SSABlock[] getSuccessors() {
 188         Cont thenCont = thenTarget.getBinding();
 189         Cont elseCont = elseTarget.getBinding();
 190         if(thenCont instanceof SSABlock) {
 191             if(elseCont instanceof SSABlock)
 192                 return new SSABlock[] {(SSABlock)thenCont, (SSABlock)elseCont};
 193             else
 194                 return new SSABlock[] {(SSABlock)thenCont};
 195         }
 196         else {
 197             if(elseCont instanceof SSABlock)
 198                 return new SSABlock[] {(SSABlock)elseCont};
 199             else
 200                 return SSABlock.EMPTY_ARRAY;
 201         }
 202     }
 203 }