bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/internal/codegen/ssa/exits/Switch.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.BranchRef;
   9 import org.simantics.scl.compiler.internal.codegen.continuations.Cont;
  10 import org.simantics.scl.compiler.internal.codegen.continuations.ContRef;
  11 import org.simantics.scl.compiler.internal.codegen.references.Val;
  12 import org.simantics.scl.compiler.internal.codegen.references.ValRef;
  13 import org.simantics.scl.compiler.internal.codegen.ssa.SSABlock;
  14 import org.simantics.scl.compiler.internal.codegen.ssa.SSAExit;
  15 import org.simantics.scl.compiler.internal.codegen.ssa.SSAFunction;
  16 import org.simantics.scl.compiler.internal.codegen.ssa.binders.ValRefBinder;
  17 import org.simantics.scl.compiler.internal.codegen.utils.CopyContext;
  18 import org.simantics.scl.compiler.internal.codegen.utils.MethodBuilder;
  19 import org.simantics.scl.compiler.internal.codegen.utils.PrintingContext;
  20 import org.simantics.scl.compiler.internal.codegen.utils.SSASimplificationContext;
  21 import org.simantics.scl.compiler.internal.codegen.utils.SSAValidationContext;
  22 import org.simantics.scl.compiler.types.TVar;
  23 import org.simantics.scl.compiler.types.Type;
  24 import org.simantics.scl.compiler.types.Types;
  25
  26 public class Switch extends SSAExit implements ValRefBinder {
  27
  28     ValRef scrutinee;
  29     BranchRef[] branches;
  30
  31     public Switch(ValRef scrutinee, BranchRef[] branches) {
  32         this.scrutinee = scrutinee;
  33         this.branches = branches;
  34         scrutinee.setParent(this);
  35         for(BranchRef branch : branches)
  36             branch.cont.setParent(this);
  37     }
  38
  39     public ValRef getScrutinee() {
  40         return scrutinee;
  41     }
  42
  43     public BranchRef[] getBranches() {
  44         return branches;
  45     }
  46
  47     @Override
  48     public void generateCode(MethodBuilder mb) {
  49         for(int i=0;i<branches.length;++i) {
  50             BranchRef branch = branches[i];
  51             if(branch.constructor == null) {
  52                 mb.jump(branch.cont);
  53             }
  54             else if(i < branches.length-1) {
  55                 Label failure = mb.createLabel();
  56                 branch.constructor.deconstruct(mb, scrutinee,
  57                         branch.cont.getBinding(), failure);
  58                 mb.setLocation(failure);
  59             }
  60             else {
  61                 branch.constructor.deconstruct(mb, scrutinee,
  62                         branch.cont.getBinding(), null);
  63             }
  64         }
  65     }
  66
  67     @Override
  68     public void toString(PrintingContext context) {
  69         context.append("switch ");
  70         context.append(scrutinee);
  71         for(BranchRef branch : branches) {
  72             context.append('\n');
  73             context.indentation();
  74             if(branch.constructor == null)
  75                 context.append("otherwise");
  76             else
  77                 context.append(branch.constructor.toString());
  78             context.append(" -> ");
  79             {
  80                 Cont cont = branch.cont.getBinding();
  81                 if(cont instanceof SSABlock) {
  82                     SSABlock block = (SSABlock)cont;
  83                     if(cont.hasMoreThanOneOccurences()) {
  84                         context.append(cont);
  85                         context.append('\n');
  86                         context.addBlock(block);
  87                     }
  88                     else {
  89                         block.parametersToString(context);
  90                         context.append('\n');
  91                         block.bodyToString(context);
  92                     }
  93                 }
  94                 else {
  95                     context.append(cont);
  96                     context.append('\n');
  97                 }
  98             }
  99         }
 100         for(SSABlock block : getSuccessors())
 101             context.addBlock(block);
 102     }
 103
 104     @Override
 105     public void validate(SSAValidationContext context) {
 106         context.validate(scrutinee);
 107         if(scrutinee.getParent() != this)
 108             throw new InternalCompilerError();
 109         for(BranchRef branch : branches) {
 110             context.validate(branch.cont);
 111             if(branch.cont.getParent() != this)
 112                 throw new InternalCompilerError();
 113         }
 114     }
 115
 116     @Override
 117     public void destroy() {
 118         scrutinee.remove();
 119         for(BranchRef branch : branches)
 120             branch.cont.remove();
 121     }
 122
 123     @Override
 124     public SSAExit copy(CopyContext context) {
 125         return new Switch(context.copy(scrutinee),
 126                 BranchRef.copy(context, branches));
 127     }
 128
 129     @Override
 130     public void replace(TVar[] vars, Type[] replacements) {
 131         scrutinee.replace(vars, replacements);
 132     }
 133
 134     @Override
 135     public void simplify(SSASimplificationContext context) {
 136         if(Types.equals(scrutinee.getType(), Types.BOOLEAN)) {
 137             ContRef thenTarget = null;
 138             ContRef elseTarget = null;
 139             for(BranchRef branch : branches) {
 140                 boolean used = false;
 141                 if(branch.constructor == null) {
 142                     if(thenTarget == null) {
 143                         thenTarget = branch.cont;
 144                         used = true;
 145                     }
 146                     if(elseTarget == null) {
 147                         elseTarget = branch.cont;
 148                         used = true;
 149                     }
 150                 }
 151                 else if(((BooleanConstant)branch.constructor).getValue()) {
 152                     if(thenTarget == null) {
 153                         thenTarget = branch.cont;
 154                         used = true;
 155                     }
 156                 }
 157                 else {
 158                     if(elseTarget == null) {
 159                         elseTarget = branch.cont;
 160                         used = true;
 161                     }
 162                 }
 163                 if(!used)
 164                     branch.cont.remove();
 165             }
 166
 167             // This may be possible if match compiler has
 168             // determined that one of the branches is not possible.
 169             if(elseTarget == null)
 170                 elseTarget = thenTarget;
 171             else if(thenTarget == null)
 172                 thenTarget = elseTarget;
 173
 174             // Replace switch by jump or if
 175             SSAExit newExit;
 176             if(thenTarget == elseTarget) {
 177                 scrutinee.remove();
 178                 newExit = new Jump(thenTarget);
 179             }
 180             else {
 181                 newExit = new If(scrutinee,
 182                         thenTarget,
 183                         elseTarget);
 184             }
 185             getParent().setExit(newExit);
 186             context.markModified("switch-to-if");
 187             newExit.simplify(context);
 188         }
 189         else if(branches.length == 1 && branches[0].constructor == null) {
 190             scrutinee.remove();
 191             getParent().setExit(new Jump(branches[0].cont));
 192         }
 193     }
 194
 195     @Override
 196     public void collectFreeVariables(SSAFunction function,
 197             ArrayList<ValRef> vars) {
 198         scrutinee.collectFreeVariables(function, vars);
 199     }
 200
 201     @Override
 202     public Cont addParametersInFrontOf(ContRef contRef, Val[] newParameters, Val[] oldParameters,
 203             Cont proxy) {
 204         if(proxy == null)
 205             proxy = contRef.getBinding().createProxy(getParent().getParent(), newParameters, oldParameters);
 206         ContRef proxyRef = proxy.createOccurrence();
 207         proxyRef.setParent(this);
 208         for(BranchRef branch : branches) {
 209             if(branch.cont == contRef) {
 210                 branch.cont = proxyRef;
 211                 break;
 212             }
 213         }
 214         return proxy;
 215     }
 216
 217     @Override
 218     public SSABlock[] getSuccessors() {
 219         ArrayList<SSABlock> result = new ArrayList<SSABlock>(branches.length);
 220         for(BranchRef branch : branches) {
 221             Cont cont = branch.cont.getBinding();
 222             if(cont instanceof SSABlock)
 223                 result.add((SSABlock)cont);
 224         }
 225         return result.toArray(new SSABlock[result.size()]);
 226     }
 227 }