Package gnu.bytecode

Class CodeAttr

java.lang.Object
gnu.bytecode.Attribute
gnu.bytecode.CodeAttr
All Implemented Interfaces:
AttrContainer
public class CodeAttr extends Attribute implements AttrContainer
Represents the contents of a standard "Code" attribute.

Most of the actual methods that generate bytecode operation are in this class (typically with names starting with emit), though there are also some in Method.

Note that a CodeAttr is an Attribute of a Method, and can in turn contain other Attributes, such as a LineNumbersAttr.

  • Field Details

    • locals

      public LocalVarsAttr locals

    • stackMap

      public StackMapTableAttr stackMap

    • GENERATE_STACK_MAP_TABLE

      public static final int GENERATE_STACK_MAP_TABLE
      See Also:

    • DONT_USE_JSR

      public static final int DONT_USE_JSR
      See Also:

    • stack_types

      public Type[] stack_types

    • instructionLineMode

      public static boolean instructionLineMode
      If true we get a line number entry for each instruction. Normally false, but can be a convenient hack to allow instruction-level stepping/debugging and stacktraces. In this case LINE==PC.

  • Constructor Details

    • CodeAttr

      public CodeAttr(Method meth)

  • Method Details

    • getAttributes

      public final Attribute getAttributes()
      Description copied from interface: AttrContainer
      Get the (first) Attribute of this container.
      Specified by:
      getAttributes in interface AttrContainer

    • setAttributes

      public final void setAttributes(Attribute attributes)
      Description copied from interface: AttrContainer
      Set the (list of) Attributes of this container.
      Specified by:
      setAttributes in interface AttrContainer

    • fixupChain

      public final void fixupChain(Label here, Label target)
      This causes a later processFixup to rearrange the code. The code at target comes here, instead of the following instructions. Fuctionally equivalent to: goto target; here:, but implemented by code re-arranging. Therefore there should be at some later point a goto here; target:.

    • fixupAdd

      public final void fixupAdd(int kind, Label label)
      Add a fixup at this location.
      Parameters:
      kind - one of the FIXUP_xxx codes.
      label - varies - typically the target of jump.

    • getMethod

      public final Method getMethod()

    • getPC

      public final int getPC()

    • getSP

      public final int getSP()

    • getConstants

      public final ConstantPool getConstants()
      Specified by:
      getConstants in interface AttrContainer
      Overrides:
      getConstants in class Attribute

    • reachableHere

      public final boolean reachableHere()
      True if control could reach here.

    • setReachable

      public final void setReachable(boolean val)

    • setUnreachable

      public final void setUnreachable()

    • getMaxStack

      public int getMaxStack()
      Get the maximum number of words on the operand stack in this method.

    • getMaxLocals

      public int getMaxLocals()
      Get the maximum number of local variable words in this method.

    • setMaxStack

      public void setMaxStack(int n)
      Set the maximum number of words on the operand stack in this method.

    • setMaxLocals

      public void setMaxLocals(int n)
      Set the maximum number of local variable words in this method.

    • getCode

      public byte[] getCode()
      Get the code (instruction bytes) of this method. Does not make a copy.

    • setCode

      public void setCode(byte[] code)
      Set the code (instruction bytes) of this method.
      Parameters:
      code - the code bytes (which are not copied). Implicitly calls setCodeLength(code.length).

    • setCodeLength

      public void setCodeLength(int len)
      Set the length the the code (instruction bytes) of this method. That is the number of current used bytes in getCode(). (Any remaing bytes provide for future growth.)

    • getCodeLength

      public int getCodeLength()
      Set the current lengthof the code (instruction bytes) of this method.

    • reserve

      public final void reserve(int bytes)

    • put1

      public final void put1(int i)
      Write an 8-bit byte to the current code-stream.
      Parameters:
      i - the byte to write

    • put2

      public final void put2(int i)
      Write a 16-bit short to the current code-stream
      Parameters:
      i - the value to write

    • put4

      public final void put4(int i)
      Write a 32-bit int to the current code-stream
      Parameters:
      i - the value to write

    • putIndex2

      public final void putIndex2(CpoolEntry cnst)

    • putLineNumber

      public final void putLineNumber(String filename, int linenumber)

    • putLineNumber

      public final void putLineNumber(int linenumber)

    • noteVarType

      public void noteVarType(int offset, Type type)

    • setTypes

      public final void setTypes(Label label)
      Set the current type state from a label.

    • setTypes

      public final void setTypes(Type[] labelLocals, Type[] labelStack)
      Set the current type state from a label.

    • pushType

      public final void pushType(Type type)

    • popType

      public final Type popType()

    • topType

      public final Type topType()

    • emitPop

      public void emitPop(int nvalues)
      Compile code to pop values off the stack (and ignore them).
      Parameters:
      nvalues - the number of values (not words) to pop

    • getLabel

      public Label getLabel()
      Get a new Label for the current location. Unlike Label.define, does not change reachableHere().

    • emitSwap

      public void emitSwap()

    • emitDup

      public void emitDup()
      Emit code to duplicate the top element of the stack.

    • emitDupX

      public void emitDupX()
      Emit code to duplicate the top element of the stack and place the copy before the previous element.

    • emitDup

      public void emitDup(int size, int offset)
      Compile code to duplicate with offset.
      Parameters:
      size - the size of the stack item to duplicate (1 or 2)
      offset - where to insert the result (must be 0, 1, or 2) The new words get inserted at stack[SP-size-offset]

    • emitDup

      public void emitDup(int size)
      Compile code to duplicate the top 1 or 2 words.
      Parameters:
      size - number of words to duplicate

    • emitDup

      public void emitDup(Type type)

    • enterScope

      public void enterScope(Scope scope)

    • pushScope

      public Scope pushScope()

    • pushAutoPoppableScope

      public Scope pushAutoPoppableScope()
      Create a Scope that is automatically popped. I.e. the next popScope will keep popping autoPop scopes until it gets to a non-autoPop scope. An autoPop Scope is useful for variables that are assigned and set in the middle of a managed Scope.

    • getCurrentScope

      public Scope getCurrentScope()

    • popScope

      public Scope popScope()

    • getArg

      public Variable getArg(int index)
      Get the index'th parameter.

    • lookup

      public Variable lookup(String name)
      Search by name for a Variable
      Parameters:
      name - name to search for
      Returns:
      the Variable, or null if not found (in any scope of this Method).

    • addLocal

      public Variable addLocal(Type type)
      Add a new local variable (in the current scope).
      Parameters:
      type - type of the new Variable.
      Returns:
      the new Variable.

    • addLocal

      public Variable addLocal(Type type, String name)
      Add a new local variable (in the current scope).
      Parameters:
      type - type of the new Variable.
      name - name of the new Variable.
      Returns:
      the new Variable.

    • addParamLocals

      public void addParamLocals()
      Call addLocal for parameters (as implied by method type).

    • emitPushConstant

      public final void emitPushConstant(int val, Type type)

    • emitPushConstant

      public final void emitPushConstant(CpoolEntry cnst)

    • emitPushInt

      public final void emitPushInt(int i)

    • emitPushLong

      public void emitPushLong(long i)

    • emitPushFloat

      public void emitPushFloat(float x)

    • emitPushDouble

      public void emitPushDouble(double x)

    • calculateSplit

      public static final String calculateSplit(String str)
      Calculate how many CONSTANT_String constants we need for a string. Each CONSTANT_String can be at most 0xFFFF bytes (as a UTF8 string). Returns a String, where each char, coerced to an int, is the length of a substring of the input that is at most 0xFFFF bytes.

    • emitPushString

      public final void emitPushString(String str)
      Emit code to push the value of a constant String. Uses CONSTANT_String and CONSTANT_Utf8 constant pool entries as needed. Can handle Strings whose UTF8 length is greates than 0xFFFF bytes (the limit of a CONSTANT_Utf8) by generating String concatenation.

    • emitPushClass

      public final void emitPushClass(ObjectType ctype)
      Push a class constant pool entry. This is only supported by JDK 1.5 and later.

    • emitPushMethodHandle

      public final void emitPushMethodHandle(Method method)
      Push a MethodHandle, using an appropriate constant pool entry. This is only supported by JDK 1.6 and later.

    • emitPushNull

      public void emitPushNull()

    • emitPushNull

      public void emitPushNull(ObjectType type)

    • emitPushDefaultValue

      public void emitPushDefaultValue(Type type)
      Push zero or null as appropriate for the given type.

    • emitStoreDefaultValue

      public void emitStoreDefaultValue(Variable var)
      Initialize a variable to zero or null, as appropriate.

    • emitPushThis

      public final void emitPushThis()

    • emitPushPrimArray

      public final void emitPushPrimArray(Object value, ArrayType arrayType)

    • emitPushPrimArray

      public final void emitPushPrimArray(Object value, int len, int count, ArrayType arrayType)
      Emit code to push a constant primitive array.
      Parameters:
      value - The array value that we want the emitted code to re-create.
      arrayType - The ArrayType that matches value.

    • emitArrayLength

      public final void emitArrayLength()

    • emitArrayStore

      public void emitArrayStore(Type element_type)
      Store into an element of an array. Must already have pushed the array reference, the index, and the new value (in that order). Stack: ..., array, index, value => ...

    • emitArrayStore

      public void emitArrayStore()
      Store into an element of an array. Must already have pushed the array reference, the index, and the new value (in that order). Stack: ..., array, index, value => ...

    • emitArrayLoad

      public void emitArrayLoad(Type element_type)
      Load an element from an array. Must already have pushed the array and the index (in that order): Stack: ..., array, index => ..., value

    • emitArrayLoad

      public void emitArrayLoad()
      Load an element from an array. Equivalent to emitArrayLoad(Type), but element_type is implied. Must already have pushed the array and the index (in that order): Stack: ..., array, index => ..., value

    • emitNew

      public void emitNew(ClassType type)
      Invoke new on a class type. Does not call the constructor!
      Parameters:
      type - the desired new object type

    • emitNewArray

      public void emitNewArray(Type element_type, int dims)
      Compile code to allocate a new array. The size should have been already pushed on the stack.
      Parameters:
      element_type - type of the array elements
      dims - number of dimensions - more than 1 is untested

    • emitNewArray

      public void emitNewArray(Type element_type)

    • emitBinop

      public void emitBinop(int base_code, Type type)

    • emitAdd

      public final void emitAdd(char sig)

    • emitAdd

      public final void emitAdd(PrimType type)

    • emitAdd

      @Deprecated public final void emitAdd()
      Deprecated.

    • emitSub

      public final void emitSub(char sig)

    • emitSub

      public final void emitSub(PrimType type)

    • emitSub

      @Deprecated public final void emitSub()
      Deprecated.

    • emitMul

      public final void emitMul()

    • emitDiv

      public final void emitDiv()

    • emitRem

      public final void emitRem()

    • emitAnd

      public final void emitAnd()

    • emitIOr

      public final void emitIOr()

    • emitXOr

      public final void emitXOr()

    • emitShl

      public final void emitShl()

    • emitShr

      public final void emitShr()

    • emitUshr

      public final void emitUshr()

    • emitNot

      public final void emitNot(Type type)
      Compile 'not', assuming 0 or 1 is on the JVM stack.

    • emitPrimop

      public void emitPrimop(int opcode, int arg_count, Type retType)

    • emitLoad

      public final void emitLoad(Variable var)
      Compile code to push the contents of a local variable onto the statck.
      Parameters:
      var - The variable whose contents we want to push.

    • emitStore

      public void emitStore(Variable var)

    • emitInc

      public void emitInc(Variable var, short inc)
      Emit an instruction to increment a variable by some amount. If the increment is zero, do nothing. The variable must contain an integral value - except if increment is zero.

    • emitGetStatic

      public final void emitGetStatic(Field field)
      Compile code to get a static field value. Stack: ... => ..., value

    • emitGetField

      public final void emitGetField(Field field)
      Compile code to get a non-static field value. Stack: ..., objectref => ..., value

    • emitPutStatic

      public final void emitPutStatic(Field field)
      Compile code to put a static field value. Stack: ..., value => ...

    • emitPutField

      public final void emitPutField(Field field)
      Compile code to put a non-static field value. Stack: ..., objectref, value => ...

    • emitInvokeMethod

      public void emitInvokeMethod(Method method, int opcode)

    • emitInvoke

      public void emitInvoke(Method method)

    • emitInvokeVirtual

      public void emitInvokeVirtual(Method method)
      Compile a virtual method call. The stack contains the 'this' object, followed by the arguments in order.
      Parameters:
      method - the method to invoke virtually

    • emitInvokeSpecial

      public void emitInvokeSpecial(Method method)

    • emitInvokeStatic

      public void emitInvokeStatic(Method method)
      Compile a static method call. The stack contains the the arguments in order.
      Parameters:
      method - the static method to invoke

    • emitInvokeInterface

      public void emitInvokeInterface(Method method)

    • emitGoto

      public final void emitGoto(Label label)
      Compile an unconditional branch (goto).
      Parameters:
      label - target of the branch (must be in this method).

    • emitJsr

      public final void emitJsr(Label label)

    • startExitableBlock

      public ExitableBlock startExitableBlock(Type resultType, boolean runFinallyBlocks)
      Enter a block which can be exited. Used to make sure finally-blocks are executed when exiting a block, loop, or method.

    • endExitableBlock

      public void endExitableBlock()
      End a block entered by a previous startExitableBlock.

    • emitGotoIfCompare1

      public final void emitGotoIfCompare1(Label label, int opcode)

    • emitGotoIfIntEqZero

      public final void emitGotoIfIntEqZero(Label label)

    • emitGotoIfIntNeZero

      public final void emitGotoIfIntNeZero(Label label)

    • emitGotoIfIntLtZero

      public final void emitGotoIfIntLtZero(Label label)

    • emitGotoIfIntGeZero

      public final void emitGotoIfIntGeZero(Label label)

    • emitGotoIfIntGtZero

      public final void emitGotoIfIntGtZero(Label label)

    • emitGotoIfIntLeZero

      public final void emitGotoIfIntLeZero(Label label)

    • emitGotoIfNull

      public final void emitGotoIfNull(Label label)

    • emitGotoIfNonNull

      public final void emitGotoIfNonNull(Label label)

    • emitGotoIfCompare2

      public final void emitGotoIfCompare2(Label label, int logop)

    • emitGotoIfEq

      @Deprecated public final void emitGotoIfEq(Label label, boolean invert)
      Deprecated.

    • emitGotoIfEq

      public final void emitGotoIfEq(Label label)
      Compile a conditional transfer if 2 top stack elements are equal.

    • emitGotoIfNE

      public final void emitGotoIfNE(Label label)
      Compile conditional transfer if 2 top stack elements are not equal.

    • emitGotoIfLt

      public final void emitGotoIfLt(Label label)

    • emitGotoIfGe

      public final void emitGotoIfGe(Label label)

    • emitGotoIfGt

      public final void emitGotoIfGt(Label label)

    • emitGotoIfLe

      public final void emitGotoIfLe(Label label)

    • emitIfCompare1

      public final void emitIfCompare1(int opcode)
      Compile start of a conditional: if (!(x opcode 0)) .... The value of x must already have been pushed.

    • emitIfIntNotZero

      public final void emitIfIntNotZero()
      Compile start of conditional: if (x != 0) .... Also use this if you have pushed a boolean value: if (b) ...

    • emitIfIntEqZero

      public final void emitIfIntEqZero()
      Compile start of conditional: if (x == 0) .... Also use this if you have pushed a boolean value: if (!b) ...

    • emitIfIntLEqZero

      public final void emitIfIntLEqZero()
      Compile start of conditional: if (x <= 0).

    • emitIfIntGEqZero

      public final void emitIfIntGEqZero()
      Compile start of conditional: if (x >= 0).

    • emitIfRefCompare1

      public final void emitIfRefCompare1(int opcode)
      Compile start of a conditional: if (!(x opcode null)) .... The value of x must already have been pushed and must be of reference type.

    • emitIfNotNull

      public final void emitIfNotNull()
      Compile start of conditional: if (x != null) ....

    • emitIfNull

      public final void emitIfNull()
      Compile start of conditional: if (x == null) ...

    • emitIfIntCompare

      public final void emitIfIntCompare(int opcode)
      Compile start of a conditional: if (!(x OPCODE y)) ... The value of x and y must already have been pushed.

    • emitIfIntLt

      public final void emitIfIntLt()

    • emitIfIntGEq

      public final void emitIfIntGEq()

    • emitIfNEq

      public final void emitIfNEq()
      Compile start of a conditional: if (x != y) ... The values of x and y must already have been pushed.

    • emitIfEq

      public final void emitIfEq()
      Compile start of a conditional: if (x == y) ... The values of x and y must already have been pushed.

    • emitIfLt

      public final void emitIfLt()
      Compile start of a conditional: if (x < y) ... The values of x and y must already have been pushed.

    • emitIfGe

      public final void emitIfGe()
      Compile start of a conditional: if (x >= y) ... The values of x and y must already have been pushed.

    • emitIfGt

      public final void emitIfGt()
      Compile start of a conditional: if (x > y) ... The values of x and y must already have been pushed.

    • emitIfLe

      public final void emitIfLe()
      Compile start of a conditional: if (x <= y) ... The values of x and y must already have been pushed.

    • emitRet

      public void emitRet(Variable var)
      Emit a 'ret' instruction.
      Parameters:
      var - the variable containing the return address

    • emitThen

      public final void emitThen()

    • emitIfThen

      public final void emitIfThen()

    • emitElse

      public final void emitElse()
      Compile start of else clause.

    • emitFi

      public final void emitFi()
      Compile end of conditional.

    • emitAndThen

      public void emitAndThen()
      Convenience for compiling if P1 && P2 then S1 else S2. Compile that as: 
       compile P1, including an appropriate emitIfXxx
 emitAndThen()
 compile P2, including an appropriate emitIfXxx
 compile S1
 emitElse
 compile S2
 emitFi

    • emitIfRaw

      public Label emitIfRaw()
      Start a new if/then/else block. The caller is responsible for evaluating the condition, and in the "false" case got the returned label. In the "true" case just continue inline.
      Returns:
      the else/end label to goto if the condition is false. A subsequent emitElse or emitFi defines the label.

    • fixUnsigned

      public final void fixUnsigned(Type stackType)

    • emitConvert

      public final void emitConvert(PrimType from, PrimType to)

    • castNeeded

      public static boolean castNeeded(Type top, Type required)

    • emitCheckcast

      public void emitCheckcast(Type type)

    • emitInstanceof

      public void emitInstanceof(Type type)

    • emitThrow

      public final void emitThrow()

    • emitMonitorEnter

      public final void emitMonitorEnter()

    • emitMonitorExit

      public final void emitMonitorExit()

    • emitReturn

      public final void emitReturn()
      Compile a method return. If inside a 'catch' clause, first call 'finally' clauses. The return value (unless the return type is void) must be on the stack, and have the correct type.

    • addHandler

      public void addHandler(int start_pc, int end_pc, int handler_pc, int catch_type)
      Add an exception handler. Low-level routine; #emitCatchStart is preferred.

    • addHandler

      public void addHandler(Label start_try, Label end_try, ClassType catch_type)
      Add an exception handler. Low-level routine; emitCatchStart(gnu.bytecode.Variable) is preferred.

    • emitWithCleanupStart

      public void emitWithCleanupStart()
      Beginning of code that has a cleanup handler. This is similar to a try-finally, but the cleanup is only done in the case of an exception. Alternatively, the try clause has to manually do the cleanup with code duplication. Equivalent to: try body catch (Throwable ex) { cleanup; throw ex; } Call emitWithCleanupStart before the body.

    • emitWithCleanupCatch

      public void emitWithCleanupCatch(Variable catchVar)
      Called after a body that has a cleanup clause. Followed by the cleanup code.

    • emitWithCleanupDone

      public void emitWithCleanupDone()
      Called after generating a cleanup handler.

    • emitTryStart

      public void emitTryStart(boolean has_finally, Type result_type)

    • emitTryEnd

      @Deprecated public void emitTryEnd()
      Deprecated.

    • emitCatchStart

      public void emitCatchStart(Variable var)

    • emitCatchStart

      public void emitCatchStart(ClassType type)

    • emitCatchEnd

      public void emitCatchEnd()

    • emitFinallyStart

      public void emitFinallyStart()

    • emitFinallyEnd

      public void emitFinallyEnd()

    • emitTryCatchEnd

      public void emitTryCatchEnd()

    • getCurrentTry

      public final TryState getCurrentTry()

    • isInTry

      public final boolean isInTry()

    • startSwitch

      public SwitchState startSwitch()
      Start a new switch statment or expression. The switch value must have been calculated and left on the stack.

    • emitTailCall

      public void emitTailCall(boolean pop_args, Label start)
      Compile a tail-call to position 0 of the current procedure.
      Parameters:
      pop_args - if true, copy argument registers (except this) from stack.
      start - the Label to jump back to.

    • emitTailCall

      public void emitTailCall(boolean pop_args, Scope scope)
      Compile a tail-call to position 0 of the current procedure.
      Parameters:
      pop_args - if true, copy argument registers (except this) from stack.
      scope - Scope whose start we jump back to.

    • processFixups

      public void processFixups()

    • assignConstants

      public void assignConstants(ClassType cl)
      Description copied from class: Attribute
      Add any needed constant pool entries for this Attribute. Overridden by sub-classes. Do any other cleanup needed before writing out a .class file.
      Overrides:
      assignConstants in class Attribute

    • getLength

      public final int getLength()
      Description copied from class: Attribute
      Return the length of the attribute in bytes. Does not include the 6-byte header (for the name_index and the length).
      Specified by:
      getLength in class Attribute

    • write

      public void write(DataOutputStream dstr) throws IOException
      Description copied from class: Attribute
      Write out the contents of the Attribute. Does not write the 6-byte attribute header.
      Specified by:
      write in class Attribute
      Throws:
      IOException

    • print

      public void print(ClassTypeWriter dst)
      Overrides:
      print in class Attribute

    • disAssemble

      public void disAssemble(ClassTypeWriter dst, int start, int limit)

    • beginFragment

      public int beginFragment(Label after)

    • beginFragment

      public int beginFragment(Label start, Label after)

    • endFragment

      public void endFragment(int cookie)
      End a fragment.
      Parameters:
      cookie - the return value from the previous beginFragment.