net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/codegen/Label.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2003 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package net.sourceforge.phpdt.internal.compiler.codegen;
  12
  13
  14 /**
  15  * This type is a port of smalltalks JavaLabel
  16  */
  17 public class Label {
  18 //      public CodeStream codeStream;
  19         final static int POS_NOT_SET = -1;
  20         public int position = POS_NOT_SET; // position=POS_NOT_SET Then it's pos is not set.
  21         public int[] forwardReferences = new int[10]; // Add an overflow check here.
  22         public int forwardReferenceCount = 0;
  23         private boolean isWide = false;
  24 public Label() {
  25 }
  26 /**
  27  * @param codeStream net.sourceforge.phpdt.internal.compiler.codegen.CodeStream
  28  */
  29 //public Label(CodeStream codeStream) {
  30 //      this.codeStream = codeStream;
  31 //}
  32 /**
  33  * Add a forward refrence for the array.
  34  */
  35 void addForwardReference(int iPos) {
  36         int length;
  37         if (forwardReferenceCount >= (length = forwardReferences.length))
  38                 System.arraycopy(forwardReferences, 0, (forwardReferences = new int[2*length]), 0, length);
  39         forwardReferences[forwardReferenceCount++] = iPos;
  40 }
  41 /**
  42  * Add a forward refrence for the array.
  43  */
  44 public void appendForwardReferencesFrom(Label otherLabel) {
  45         int otherCount = otherLabel.forwardReferenceCount;
  46         if (otherCount == 0) return;
  47         int length = forwardReferences.length;
  48         int neededSpace = otherCount + forwardReferenceCount;
  49         if (neededSpace >= length){
  50                 System.arraycopy(forwardReferences, 0, (forwardReferences = new int[neededSpace]), 0, forwardReferenceCount);
  51         }
  52         // append other forward references at the end, so they will get updated as well
  53         System.arraycopy(otherLabel.forwardReferences, 0, forwardReferences, forwardReferenceCount, otherCount);
  54         forwardReferenceCount = neededSpace;
  55 }
  56 /*
  57 * Put down  a refernece to the array at the location in the codestream.
  58 */
  59 //void branch() {
  60 //      if (position == POS_NOT_SET) {
  61 //              addForwardReference(codeStream.position);
  62 //              // Leave two bytes free to generate the jump afterwards
  63 //              codeStream.position += 2;
  64 //              codeStream.classFileOffset += 2;
  65 //      } else {
  66 //              /*
  67 //               * Position is set. Write it if it is not a wide branch.
  68 //               */
  69 //              int offset = position - codeStream.position + 1;
  70 //              if (Math.abs(offset) > 0x7FFF && !this.codeStream.wideMode) {
  71 //                      throw new AbortMethod(CodeStream.RESTART_IN_WIDE_MODE);
  72 //              }
  73 //              codeStream.writeSignedShort((short) offset);
  74 //      }
  75 //}
  76 /*
  77 * No support for wide branches yet
  78 */
  79 //void branchWide() {
  80 //      if (position == POS_NOT_SET) {
  81 //              addForwardReference(codeStream.position);
  82 //              // Leave 4 bytes free to generate the jump offset afterwards
  83 //              isWide = true;
  84 //              codeStream.position += 4;
  85 //              codeStream.classFileOffset += 4;
  86 //      } else { //Position is set. Write it!
  87 //              codeStream.writeSignedWord(position - codeStream.position + 1);
  88 //      }
  89 //}
  90 /**
  91  * @return boolean
  92  */
  93 public boolean hasForwardReferences() {
  94         return forwardReferenceCount != 0;
  95 }
  96 /*
  97  * Some placed labels might be branching to a goto bytecode which we can optimize better.
  98  */
  99 //public void inlineForwardReferencesFromLabelsTargeting(int gotoLocation) {
 100 ///*
 101 // Code required to optimized unreachable gotos.
 102 //      public boolean isBranchTarget(int location) {
 103 //              Label[] labels = codeStream.labels;
 104 //              for (int i = codeStream.countLabels - 1; i >= 0; i--){
 105 //                      Label label = labels[i];
 106 //                      if ((label.position == location) && label.isStandardLabel()){
 107 //                              return true;
 108 //                      }
 109 //              }
 110 //              return false;
 111 //      }
 112 // */
 113 //
 114 //      Label[] labels = codeStream.labels;
 115 //      for (int i = codeStream.countLabels - 1; i >= 0; i--){
 116 //              Label label = labels[i];
 117 //              if ((label.position == gotoLocation) && label.isStandardLabel()){
 118 //                      this.appendForwardReferencesFrom(label);
 119 //                      /*
 120 //                       Code required to optimized unreachable gotos.
 121 //                              label.position = POS_NOT_SET;
 122 //                      */
 123 //              } else {
 124 //                      break; // same target labels should be contiguous
 125 //              }
 126 //      }
 127 //}
 128 public boolean isStandardLabel(){
 129         return true;
 130 }
 131 /*
 132 * Place the label. If we have forward references resolve them.
 133 */
 134 //public void place() { // Currently lacking wide support.
 135 //      if (position == POS_NOT_SET) {
 136 //              position = codeStream.position;
 137 //              codeStream.addLabel(this);
 138 //              int oldPosition = position;
 139 //              boolean optimizedBranch = false;
 140 //              // TURNED OFF since fail on 1F4IRD9
 141 //              if (forwardReferenceCount != 0) {
 142 //                      if (optimizedBranch = (forwardReferences[forwardReferenceCount - 1] + 2 == position) && (codeStream.bCodeStream[codeStream.classFileOffset - 3] == CodeStream.OPC_goto)) {
 143 //                              codeStream.position = (position -= 3);
 144 //                              codeStream.classFileOffset -= 3;
 145 //                              forwardReferenceCount--;
 146 //                              // also update the PCs in the related debug attributes
 147 //                              /** OLD CODE
 148 //                                      int index = codeStream.pcToSourceMapSize - 1;
 149 //                                              while ((index >= 0) && (codeStream.pcToSourceMap[index][1] == oldPosition)) {
 150 //                                                      codeStream.pcToSourceMap[index--][1] = position;
 151 //                                              }
 152 //                              */
 153 //                              // Beginning of new code
 154 //                              int index = codeStream.pcToSourceMapSize - 2;
 155 //                              if (codeStream.lastEntryPC == oldPosition) {
 156 //                                      codeStream.lastEntryPC = position;
 157 //                              }
 158 //                              if ((index >= 0) && (codeStream.pcToSourceMap[index] == position)) {
 159 //                                      codeStream.pcToSourceMapSize-=2;
 160 //                              }
 161 //                              // end of new code
 162 //                              if (codeStream.generateLocalVariableTableAttributes) {
 163 //                                      LocalVariableBinding locals[] = codeStream.locals;
 164 //                                      for (int i = 0, max = locals.length; i < max; i++) {
 165 //                                              LocalVariableBinding local = locals[i];
 166 //                                              if ((local != null) && (local.initializationCount > 0)) {
 167 //                                                      if (local.initializationPCs[((local.initializationCount - 1) << 1) + 1] == oldPosition) {
 168 //                                                              // we want to prevent interval of size 0 to have a negative size.
 169 //                                                              // see PR 1GIRQLA: ITPJCORE:ALL - ClassFormatError for local variable attribute
 170 //                                                              local.initializationPCs[((local.initializationCount - 1) << 1) + 1] = position;
 171 //                                                      }
 172 //                                                      if (local.initializationPCs[(local.initializationCount - 1) << 1] == oldPosition) {
 173 //                                                              local.initializationPCs[(local.initializationCount - 1) << 1] = position;
 174 //                                                      }
 175 //                                              }
 176 //                                      }
 177 //                              }
 178 //                      }
 179 //              }
 180 //              for (int i = 0; i < forwardReferenceCount; i++) {
 181 //                      int offset = position - forwardReferences[i] + 1;
 182 //                      if (Math.abs(offset) > 0x7FFF && !this.codeStream.wideMode) {
 183 //                              throw new AbortMethod(CodeStream.RESTART_IN_WIDE_MODE);
 184 //                      }
 185 //                      if (this.codeStream.wideMode) {
 186 //                              if (this.isWide) {
 187 //                                      codeStream.writeSignedWord(forwardReferences[i], offset);
 188 //                              } else {
 189 //                                      codeStream.writeSignedShort(forwardReferences[i], (short) offset);
 190 //                              }
 191 //                      } else {
 192 //                              codeStream.writeSignedShort(forwardReferences[i], (short) offset);
 193 //                      }
 194 //              }
 195 //              // For all labels placed at that position we check if we need to rewrite the jump
 196 //              // offset. It is the case each time a label had a forward reference to the current position.
 197 //              // Like we change the current position, we have to change the jump offset. See 1F4IRD9 for more details.
 198 //              if (optimizedBranch) {
 199 //                      for (int i = 0; i < codeStream.countLabels; i++) {
 200 //                              Label label = codeStream.labels[i];
 201 //                              if (oldPosition == label.position) {
 202 //                                      label.position = position;
 203 //                                      if (label instanceof CaseLabel) {
 204 //                                              int offset = position - ((CaseLabel) label).instructionPosition;
 205 //                                              for (int j = 0; j < label.forwardReferenceCount; j++) {
 206 //                                                      int forwardPosition = label.forwardReferences[j];
 207 //                                                      codeStream.writeSignedWord(forwardPosition, offset);
 208 //                                              }
 209 //                                      } else {
 210 //                                              for (int j = 0; j < label.forwardReferenceCount; j++) {
 211 //                                                      int forwardPosition = label.forwardReferences[j];
 212 //                                                      int offset = position - forwardPosition + 1;
 213 //                                                      if (Math.abs(offset) > 0x7FFF && !this.codeStream.wideMode) {
 214 //                                                              throw new AbortMethod(CodeStream.RESTART_IN_WIDE_MODE);
 215 //                                                      }
 216 //                                                      if (this.codeStream.wideMode) {
 217 //                                                              if (this.isWide) {
 218 //                                                                      codeStream.writeSignedWord(forwardPosition, offset);
 219 //                                                              } else {
 220 //                                                                      codeStream.writeSignedShort(forwardPosition, (short) offset);
 221 //                                                              }
 222 //                                                      } else {
 223 //                                                              codeStream.writeSignedShort(forwardPosition, (short) offset);
 224 //                                                      }
 225 //                                              }
 226 //                                      }
 227 //                              }
 228 //                      }
 229 //              }
 230 //      }
 231 //}
 232 /**
 233  * Print out the receiver
 234  */
 235 public String toString() {
 236         StringBuffer buffer = new StringBuffer("(position="); //$NON-NLS-1$
 237         buffer.append(position);
 238         buffer.append(", forwards = ["); //$NON-NLS-1$
 239         for (int i = 0; i < forwardReferenceCount - 1; i++)
 240                 buffer.append(forwardReferences[i] + ", "); //$NON-NLS-1$
 241         if (forwardReferenceCount >= 1)
 242                 buffer.append(forwardReferences[forwardReferenceCount-1]);
 243         buffer.append("] )"); //$NON-NLS-1$
 244         return buffer.toString();
 245 }
 246
 247 public void resetStateForCodeGeneration() {
 248         this.position = POS_NOT_SET;
 249         this.forwardReferenceCount = 0;
 250 }
 251 }