com.android.dx.cf.code
Class BasicBlocker

java.lang.Object
  com.android.dx.cf.code.BasicBlocker

All Implemented Interfaces:

BytecodeArray.Visitor

public final class BasicBlocker
extends Object
implements BytecodeArray.Visitor

Utility that identifies basic blocks in bytecode.

Method Summary

int	getPreviousOffset() Get previous bytecode offset
static ByteBlockList	identifyBlocks(ConcreteMethod method) Identifies and enumerates the basic blocks in the given method, returning a list of them.
void	setPreviousOffset(int offset) Set previous bytecode offset
void	visitBranch(int opcode, int offset, int length, int target) Visits an instruction which has a branch target argument.
void	visitConstant(int opcode, int offset, int length, Constant cst, int value) Visits an instruction which has a (possibly synthetic) constant argument, and possibly also an additional literal integer argument.
void	visitInvalid(int opcode, int offset, int length) Visits an invalid instruction.
void	visitLocal(int opcode, int offset, int length, int idx, Type type, int value) Visits an instruction which has a local variable index argument.
void	visitNewarray(int offset, int length, CstType type, ArrayList<Constant> intVals) Visits a newarray instruction.
void	visitNoArgs(int opcode, int offset, int length, Type type) Visits an instruction which has no inline arguments (implicit or explicit).
void	visitSwitch(int opcode, int offset, int length, SwitchList cases, int padding) Visits a switch instruction.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

identifyBlocks

public static ByteBlockList identifyBlocks(ConcreteMethod method)

Identifies and enumerates the basic blocks in the given method, returning a list of them. The returned list notably omits any definitely-dead code that is identified in the process.

Parameters:

method - non-null; method to convert

Returns:

non-null; list of basic blocks

visitInvalid

public void visitInvalid(int opcode,
                         int offset,
                         int length)

Visits an invalid instruction.

Specified by:

visitInvalid in interface BytecodeArray.Visitor

Parameters:

opcode - the opcode

offset - offset to the instruction

length - length of the instruction, in bytes

visitNoArgs

public void visitNoArgs(int opcode,
                        int offset,
                        int length,
                        Type type)

Visits an instruction which has no inline arguments (implicit or explicit).

Specified by:

visitNoArgs in interface BytecodeArray.Visitor

Parameters:

opcode - the opcode

offset - offset to the instruction

length - length of the instruction, in bytes

type - non-null; type the instruction operates on

visitLocal

public void visitLocal(int opcode,
                       int offset,
                       int length,
                       int idx,
                       Type type,
                       int value)

Visits an instruction which has a local variable index argument.

Specified by:

visitLocal in interface BytecodeArray.Visitor

Parameters:

opcode - the opcode

offset - offset to the instruction

length - length of the instruction, in bytes

idx - the local variable index

type - non-null; the type of the accessed value

value - additional literal integer argument, if salient (i.e., for iinc)

visitConstant

public void visitConstant(int opcode,
                          int offset,
                          int length,
                          Constant cst,
                          int value)

Visits an instruction which has a (possibly synthetic) constant argument, and possibly also an additional literal integer argument. In the case of multianewarray, the argument is the count of dimensions. In the case of invokeinterface, the argument is the parameter count or'ed with the should-be-zero value left-shifted by 8. In the case of entries of type int, the value field always holds the raw value (for convenience of clients).

Note: In order to avoid giving it a barely-useful visitor all its own, newarray also uses this form, passing value as the array type code and cst as a CstType instance corresponding to the array type.

Specified by:

visitConstant in interface BytecodeArray.Visitor

Parameters:

opcode - the opcode

offset - offset to the instruction

length - length of the instruction, in bytes

cst - non-null; the constant

value - additional literal integer argument, if salient (ignore if not)

visitBranch

public void visitBranch(int opcode,
                        int offset,
                        int length,
                        int target)

Visits an instruction which has a branch target argument.

Specified by:

visitBranch in interface BytecodeArray.Visitor

Parameters:

opcode - the opcode

offset - offset to the instruction

length - length of the instruction, in bytes

target - the absolute (not relative) branch target

visitSwitch

public void visitSwitch(int opcode,
                        int offset,
                        int length,
                        SwitchList cases,
                        int padding)

Visits a switch instruction.

Specified by:

visitSwitch in interface BytecodeArray.Visitor

Parameters:

opcode - the opcode

offset - offset to the instruction

length - length of the instruction, in bytes

cases - non-null; list of (value, target) pairs, plus the default target

padding - the bytes found in the padding area (if any), packed

visitNewarray

public void visitNewarray(int offset,
                          int length,
                          CstType type,
                          ArrayList<Constant> intVals)

Visits a newarray instruction.

Specified by:

visitNewarray in interface BytecodeArray.Visitor

Parameters:

offset - offset to the instruction

length - length of the instruction, in bytes

type - non-null; the type of the array

intVals - non-null; list of bytecode offsets for init values

setPreviousOffset

public void setPreviousOffset(int offset)

Set previous bytecode offset

Specified by:

setPreviousOffset in interface BytecodeArray.Visitor

Parameters:

offset - offset of the previous fully parsed bytecode

getPreviousOffset

public int getPreviousOffset()

Get previous bytecode offset

Specified by:

getPreviousOffset in interface BytecodeArray.Visitor

Returns:

return the recored offset of the previous bytecode