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src/java.base/share/classes/jdk/internal/classfile/impl/DirectCodeBuilder.java

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  23  * or visit www.oracle.com if you need additional information or have any
  24  * questions.
  25  */
  26 package jdk.internal.classfile.impl;
  27 
  28 import java.lang.classfile.*;
  29 import java.lang.classfile.attribute.CodeAttribute;
  30 import java.lang.classfile.attribute.LineNumberTableAttribute;
  31 import java.lang.classfile.constantpool.*;
  32 import java.lang.classfile.instruction.CharacterRange;
  33 import java.lang.classfile.instruction.ExceptionCatch;
  34 import java.lang.classfile.instruction.LocalVariable;
  35 import java.lang.classfile.instruction.LocalVariableType;
  36 import java.lang.classfile.instruction.SwitchCase;
  37 import java.lang.constant.ClassDesc;
  38 import java.lang.constant.MethodTypeDesc;
  39 import java.util.*;
  40 import java.util.function.Consumer;
  41 import java.util.function.Function;
  42 

  43 import static java.util.Objects.requireNonNull;
  44 import static jdk.internal.classfile.impl.BytecodeHelpers.*;
  45 import static jdk.internal.classfile.impl.RawBytecodeHelper.*;
  46 
  47 public final class DirectCodeBuilder
  48         extends AbstractDirectBuilder<CodeModel>
  49         implements TerminalCodeBuilder {
  50     private static final CharacterRange[] EMPTY_CHARACTER_RANGE = {};
  51     private static final LocalVariable[] EMPTY_LOCAL_VARIABLE_ARRAY = {};
  52     private static final LocalVariableType[] EMPTY_LOCAL_VARIABLE_TYPE_ARRAY = {};
  53     private static final DeferredLabel[] EMPTY_DEFERRED_LABEL_ARRAY = {};
  54 
  55     final List<AbstractPseudoInstruction.ExceptionCatchImpl> handlers = new ArrayList<>();
  56     private CharacterRange[] characterRanges = EMPTY_CHARACTER_RANGE;
  57     private LocalVariable[] localVariables = EMPTY_LOCAL_VARIABLE_ARRAY;
  58     private LocalVariableType[] localVariableTypes = EMPTY_LOCAL_VARIABLE_TYPE_ARRAY;
  59     private int characterRangesCount = 0;
  60     private int localVariablesCount = 0;
  61     private int localVariableTypesCount = 0;
  62     private final boolean transformDeferredJumps, transformKnownJumps;

 356                         }
 357                     }
 358                 } else {
 359                     writeCounters(codeMatch, buf);
 360                 }
 361             }
 362 
 363             @Override
 364             public void writeBody(BufWriterImpl buf) {
 365                 DirectCodeBuilder dcb = DirectCodeBuilder.this;
 366 
 367                 int codeLength = curPc();
 368                 if (codeLength == 0 || codeLength >= 65536) {
 369                     throw new IllegalArgumentException(String.format(
 370                             "Code length %d is outside the allowed range in %s%s",
 371                             codeLength,
 372                             dcb.methodInfo.methodName().stringValue(),
 373                             dcb.methodInfo.methodTypeSymbol().displayDescriptor()));
 374                 }
 375 
 376                 boolean codeMatch = dcb.original != null && codeAndExceptionsMatch(codeLength);
 377                 buf.setLabelContext(dcb, codeMatch);
 378                 var context = dcb.context;
 379                 if (context.stackMapsWhenRequired()) {
 380                     if (codeMatch) {
 381                         dcb.attributes.withAttribute(dcb.original.findAttribute(Attributes.stackMapTable()).orElse(null));
 382                         writeCounters(true, buf);
 383                     } else {
 384                         tryGenerateStackMaps(false, buf);
 385                     }
 386                 } else if (context.generateStackMaps()) {
 387                     generateStackMaps(buf);
 388                 } else if (context.dropStackMaps()) {
 389                     writeCounters(codeMatch, buf);
 390                 }
 391 
 392                 buf.writeInt(codeLength);
 393                 buf.writeBytes(dcb.bytecodesBufWriter);
 394                 dcb.writeExceptionHandlers(buf);
 395                 dcb.attributes.writeTo(buf);
 396                 buf.setLabelContext(null, false);

 435         @Override
 436         public void writeBody(BufWriterImpl b) {
 437             throw new UnsupportedOperationException();
 438         }
 439 
 440         @Override
 441         public void writeTo(BufWriterImpl b) {
 442             b.writeIndex(b.constantPool().utf8Entry(Attributes.NAME_LINE_NUMBER_TABLE));
 443             push();
 444             b.writeInt(buf.size() + 2);
 445             b.writeU2(buf.size() / 4);
 446             b.writeBytes(buf);
 447         }
 448 
 449         @Override
 450         public Utf8Entry attributeName() {
 451             return buf.constantPool().utf8Entry(Attributes.NAME_LINE_NUMBER_TABLE);
 452         }
 453     }
 454 
 455     private boolean codeAndExceptionsMatch(int codeLength) {
 456         boolean codeAttributesMatch;
 457         if (original instanceof CodeImpl cai && canWriteDirect(cai.constantPool())) {
 458             codeAttributesMatch = cai.codeLength == curPc()
 459                                   && cai.compareCodeBytes(bytecodesBufWriter, 0, codeLength);
 460             if (codeAttributesMatch) {
 461                 var bw = new BufWriterImpl(constantPool, context);
 462                 writeExceptionHandlers(bw);
 463                 codeAttributesMatch = cai.classReader.compare(bw, 0, cai.exceptionHandlerPos, bw.size());
 464             }
















 465         }
 466         else
 467             codeAttributesMatch = false;
 468         return codeAttributesMatch;
 469     }
 470 
 471     // Writing support
 472 
 473     private record DeferredLabel(int labelPc, int size, int instructionPc, Label label) { }
 474 
 475     private void processDeferredLabels() {
 476         for (int i = 0; i < deferredLabelsCount; i++) {
 477             DeferredLabel dl = deferredLabels[i];
 478             int branchOffset = labelToBci(dl.label) - dl.instructionPc;
 479             if (dl.size == 2) {
 480                 if ((short) branchOffset != branchOffset) throw new LabelOverflowException();
 481                 bytecodesBufWriter.patchU2(dl.labelPc, branchOffset);
 482             } else {
 483                 assert dl.size == 4;
 484                 bytecodesBufWriter.patchInt(dl.labelPc, branchOffset);

  23  * or visit www.oracle.com if you need additional information or have any
  24  * questions.
  25  */
  26 package jdk.internal.classfile.impl;
  27 
  28 import java.lang.classfile.*;
  29 import java.lang.classfile.attribute.CodeAttribute;
  30 import java.lang.classfile.attribute.LineNumberTableAttribute;
  31 import java.lang.classfile.constantpool.*;
  32 import java.lang.classfile.instruction.CharacterRange;
  33 import java.lang.classfile.instruction.ExceptionCatch;
  34 import java.lang.classfile.instruction.LocalVariable;
  35 import java.lang.classfile.instruction.LocalVariableType;
  36 import java.lang.classfile.instruction.SwitchCase;
  37 import java.lang.constant.ClassDesc;
  38 import java.lang.constant.MethodTypeDesc;
  39 import java.util.*;
  40 import java.util.function.Consumer;
  41 import java.util.function.Function;
  42 
  43 import static java.lang.constant.ConstantDescs.INIT_NAME;
  44 import static java.util.Objects.requireNonNull;
  45 import static jdk.internal.classfile.impl.BytecodeHelpers.*;
  46 import static jdk.internal.classfile.impl.RawBytecodeHelper.*;
  47 
  48 public final class DirectCodeBuilder
  49         extends AbstractDirectBuilder<CodeModel>
  50         implements TerminalCodeBuilder {
  51     private static final CharacterRange[] EMPTY_CHARACTER_RANGE = {};
  52     private static final LocalVariable[] EMPTY_LOCAL_VARIABLE_ARRAY = {};
  53     private static final LocalVariableType[] EMPTY_LOCAL_VARIABLE_TYPE_ARRAY = {};
  54     private static final DeferredLabel[] EMPTY_DEFERRED_LABEL_ARRAY = {};
  55 
  56     final List<AbstractPseudoInstruction.ExceptionCatchImpl> handlers = new ArrayList<>();
  57     private CharacterRange[] characterRanges = EMPTY_CHARACTER_RANGE;
  58     private LocalVariable[] localVariables = EMPTY_LOCAL_VARIABLE_ARRAY;
  59     private LocalVariableType[] localVariableTypes = EMPTY_LOCAL_VARIABLE_TYPE_ARRAY;
  60     private int characterRangesCount = 0;
  61     private int localVariablesCount = 0;
  62     private int localVariableTypesCount = 0;
  63     private final boolean transformDeferredJumps, transformKnownJumps;

 357                         }
 358                     }
 359                 } else {
 360                     writeCounters(codeMatch, buf);
 361                 }
 362             }
 363 
 364             @Override
 365             public void writeBody(BufWriterImpl buf) {
 366                 DirectCodeBuilder dcb = DirectCodeBuilder.this;
 367 
 368                 int codeLength = curPc();
 369                 if (codeLength == 0 || codeLength >= 65536) {
 370                     throw new IllegalArgumentException(String.format(
 371                             "Code length %d is outside the allowed range in %s%s",
 372                             codeLength,
 373                             dcb.methodInfo.methodName().stringValue(),
 374                             dcb.methodInfo.methodTypeSymbol().displayDescriptor()));
 375                 }
 376 
 377                 boolean codeMatch = dcb.codeAndExceptionsMatch(codeLength, buf);
 378                 buf.setLabelContext(dcb, codeMatch);
 379                 var context = dcb.context;
 380                 if (context.stackMapsWhenRequired()) {
 381                     if (codeMatch) {
 382                         dcb.attributes.withAttribute(dcb.original.findAttribute(Attributes.stackMapTable()).orElse(null));
 383                         writeCounters(true, buf);
 384                     } else {
 385                         tryGenerateStackMaps(false, buf);
 386                     }
 387                 } else if (context.generateStackMaps()) {
 388                     generateStackMaps(buf);
 389                 } else if (context.dropStackMaps()) {
 390                     writeCounters(codeMatch, buf);
 391                 }
 392 
 393                 buf.writeInt(codeLength);
 394                 buf.writeBytes(dcb.bytecodesBufWriter);
 395                 dcb.writeExceptionHandlers(buf);
 396                 dcb.attributes.writeTo(buf);
 397                 buf.setLabelContext(null, false);

 436         @Override
 437         public void writeBody(BufWriterImpl b) {
 438             throw new UnsupportedOperationException();
 439         }
 440 
 441         @Override
 442         public void writeTo(BufWriterImpl b) {
 443             b.writeIndex(b.constantPool().utf8Entry(Attributes.NAME_LINE_NUMBER_TABLE));
 444             push();
 445             b.writeInt(buf.size() + 2);
 446             b.writeU2(buf.size() / 4);
 447             b.writeBytes(buf);
 448         }
 449 
 450         @Override
 451         public Utf8Entry attributeName() {
 452             return buf.constantPool().utf8Entry(Attributes.NAME_LINE_NUMBER_TABLE);
 453         }
 454     }
 455 
 456     private boolean codeAndExceptionsMatch(int codeLength, BufWriterImpl buf) {
 457         boolean codeAttributesMatch;
 458         if (original instanceof CodeImpl cai && canWriteDirect(cai.constantPool())) {
 459             codeAttributesMatch = cai.codeLength == curPc()
 460                                   && cai.compareCodeBytes(bytecodesBufWriter, 0, codeLength);
 461             if (codeAttributesMatch) {
 462                 var bw = new BufWriterImpl(constantPool, context);
 463                 writeExceptionHandlers(bw);
 464                 codeAttributesMatch = cai.classReader.compare(bw, 0, cai.exceptionHandlerPos, bw.size());
 465             }
 466 
 467             if (codeAttributesMatch) {
 468                 var thisIsConstructor = methodInfo.methodName().equalsString(INIT_NAME);
 469                 var originalIsConstructor = cai.enclosingMethod.methodName().equalsString(INIT_NAME);
 470                 if (thisIsConstructor || originalIsConstructor) {
 471                     if (thisIsConstructor != originalIsConstructor) {
 472                         codeAttributesMatch = false;
 473                     }
 474                 }
 475 
 476                 if (codeAttributesMatch && thisIsConstructor) {
 477                     if (!buf.strictFieldsMatch(cai.classReader.getContainedClass())) {
 478                         codeAttributesMatch = false;
 479                     }
 480                 }
 481             }
 482         }
 483         else
 484             codeAttributesMatch = false;
 485         return codeAttributesMatch;
 486     }
 487 
 488     // Writing support
 489 
 490     private record DeferredLabel(int labelPc, int size, int instructionPc, Label label) { }
 491 
 492     private void processDeferredLabels() {
 493         for (int i = 0; i < deferredLabelsCount; i++) {
 494             DeferredLabel dl = deferredLabels[i];
 495             int branchOffset = labelToBci(dl.label) - dl.instructionPc;
 496             if (dl.size == 2) {
 497                 if ((short) branchOffset != branchOffset) throw new LabelOverflowException();
 498                 bytecodesBufWriter.patchU2(dl.labelPc, branchOffset);
 499             } else {
 500                 assert dl.size == 4;
 501                 bytecodesBufWriter.patchInt(dl.labelPc, branchOffset);
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