Package gnu.bytecode

Class 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 Detail

      • GENERATE_STACK_MAP_TABLE

        public static final int GENERATE_STACK_MAP_TABLE
        See Also:
        Constant Field Values

      • 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 Detail

      • CodeAttr

        public CodeAttr​(Method meth)

    • Method Detail

      • 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()

      • 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)

      • 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.

      • 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

      • 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.