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Iterative logic to handle embiggening of goto instructions, when subsequent code shifts are inserted. Layout logic creates a HashMap of predicted instruction replacements and nop insertions to be used later in writing method, which is more cromulent solution than simply replicating the logic, given its iterativeness.

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This commit is contained in:
Izzat Bahadirov 2013-03-08 19:22:34 -05:00
parent 15ae0affc4
commit 5df16db108
1 changed files with 68 additions and 46 deletions
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114
dexlib2/src/main/java/org/jf/dexlib2/writer/util/InstructionWriteUtil.java
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@ -50,6 +50,7 @@ import org.jf.util.ExceptionWithContext;
import javax.annotation.Nonnull;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class InstructionWriteUtil {
@ -58,6 +59,7 @@ public class InstructionWriteUtil {
private List<Instruction> instructions;
private ArrayList<Integer> codeOffsetShifts;
private HashMap<Integer,Format> offsetToNewInstructionMap;
private int codeUnitCount;
private int outParamCount;
@ -148,7 +150,11 @@ public class InstructionWriteUtil {
if (codeOffsetShifts == null) {
codeOffsetShifts = new ArrayList<Integer>();
}
if (offsetToNewInstructionMap == null) {
offsetToNewInstructionMap = new HashMap<Integer,Format>();
}
codeOffsetShifts.add(currentCodeOffset+instruction.getCodeUnits());
offsetToNewInstructionMap.put(currentCodeOffset, instruction.getOpcode().format);
}
}
currentCodeOffset += instruction.getCodeUnits();
@ -162,38 +168,55 @@ public class InstructionWriteUtil {
// since code offset delta is equivalent to the position of instruction's code offset in the shift list,
// we use it as a position here
// we also check if we will have to insert nops to ensure 4-byte alignment for switch statements and packed arrays
currentCodeOffset = 0;
for (Instruction instruction: methodImplementation.getInstructions()) {
if (instruction.getOpcode().format.equals(Format.Format10t)) {
int targetOffset = ((Instruction10t)instruction).getCodeOffset();
int codeOffsetDelta = codeOffsetShift(currentCodeOffset);
int newTargetOffset = targetOffset + targetOffsetShift(currentCodeOffset, targetOffset);
if ((byte)newTargetOffset != newTargetOffset) {
if ((short)newTargetOffset != newTargetOffset) {
// handling very small (negligible) possibility of goto becoming goto/32
// we insert extra 1 code unit shift referring to the same position
// this will cause subsequent code offsets to be shifted by 2 code units
boolean shiftsInserted;
do {
currentCodeOffset = 0;
shiftsInserted = false;
for (Instruction instruction: methodImplementation.getInstructions()) {
if (instruction.getOpcode().format.equals(Format.Format10t) && !offsetToNewInstructionMap.containsKey(currentCodeOffset)) {
int targetOffset = ((Instruction10t)instruction).getCodeOffset();
int codeOffsetDelta = codeOffsetShift(currentCodeOffset);
int newTargetOffset = targetOffset + targetOffsetShift(currentCodeOffset, targetOffset);
if ((byte)newTargetOffset != newTargetOffset) {
if ((short)newTargetOffset != newTargetOffset) {
// handling very small (negligible) possibility of goto becoming goto/32
// we insert extra 1 code unit shift referring to the same position
// this will cause subsequent code offsets to be shifted by 2 code units
codeOffsetShifts.add(codeOffsetDelta, currentCodeOffset+instruction.getCodeUnits());
offsetToNewInstructionMap.put(currentCodeOffset, Format.Format30t);
} else {
offsetToNewInstructionMap.put(currentCodeOffset, Format.Format20t);
}
codeOffsetShifts.add(codeOffsetDelta, currentCodeOffset+instruction.getCodeUnits());
}
codeOffsetShifts.add(codeOffsetDelta, currentCodeOffset+instruction.getCodeUnits());
shiftsInserted = true;
}
} else if (instruction.getOpcode().format.equals(Format.Format20t) && !offsetToNewInstructionMap.containsKey(currentCodeOffset)) {
int targetOffset = ((Instruction20t)instruction).getCodeOffset();
int codeOffsetDelta = codeOffsetShift(currentCodeOffset);
int newTargetOffset = targetOffsetShift(currentCodeOffset, targetOffset);
if ((short)newTargetOffset != newTargetOffset) {
codeOffsetShifts.add(codeOffsetDelta, currentCodeOffset+instruction.getCodeUnits());
offsetToNewInstructionMap.put(currentCodeOffset, Format.Format30t);
shiftsInserted = true;
}
} else if (instruction.getOpcode().format.equals(Format.ArrayPayload)
|| instruction.getOpcode().format.equals(Format.SparseSwitchPayload)
|| instruction.getOpcode().format.equals(Format.PackedSwitchPayload)) {
int codeOffsetDelta = codeOffsetShift(currentCodeOffset);
if ((currentCodeOffset+codeOffsetDelta)%2 != 0) {
if (codeOffsetShifts.contains(currentCodeOffset)) {
codeOffsetShifts.remove(codeOffsetDelta);
offsetToNewInstructionMap.remove(currentCodeOffset);
} else {
codeOffsetShifts.add(codeOffsetDelta, currentCodeOffset);
offsetToNewInstructionMap.put(currentCodeOffset, Format.Format10x);
shiftsInserted = true;
}
}
}
} else if (instruction.getOpcode().format.equals(Format.Format20t)) {
int targetOffset = ((Instruction20t)instruction).getCodeOffset();
int codeOffsetDelta = codeOffsetShift(currentCodeOffset);
int newTargetOffset = targetOffsetShift(currentCodeOffset, targetOffset);
if ((short)newTargetOffset != newTargetOffset) {
codeOffsetShifts.add(codeOffsetDelta, currentCodeOffset+instruction.getCodeUnits());
}
} else if (instruction.getOpcode().format.equals(Format.ArrayPayload)
|| instruction.getOpcode().format.equals(Format.SparseSwitchPayload)
|| instruction.getOpcode().format.equals(Format.PackedSwitchPayload)) {
int codeOffsetDelta = codeOffsetShift(currentCodeOffset);
if ((currentCodeOffset+codeOffsetDelta)%2 != 0) {
codeOffsetShifts.add(codeOffsetDelta, currentCodeOffset);
}
}
currentCodeOffset += instruction.getCodeUnits();
}
currentCodeOffset += instruction.getCodeUnits();
}
} while (shiftsInserted);
codeUnitCount += codeOffsetShifts.size();
}
@ -212,16 +235,15 @@ public class InstructionWriteUtil {
Instruction10t instr = (Instruction10t)instruction;
int targetOffset = instr.getCodeOffset();
int newTargetOffset = targetOffset + targetOffsetShift(currentCodeOffset, targetOffset);
if (newTargetOffset != targetOffset) {
if ((byte)newTargetOffset != newTargetOffset) {
if ((short)newTargetOffset != newTargetOffset) {
modifiedInstruction = new ImmutableInstruction30t(Opcode.GOTO_32, newTargetOffset);
} else {
modifiedInstruction = new ImmutableInstruction20t(Opcode.GOTO_16, newTargetOffset);
}
} else {
modifiedInstruction = new ImmutableInstruction10t(instr.getOpcode(), newTargetOffset);
Format newInstructionFormat = offsetToNewInstructionMap.get(currentCodeOffset);
if (newInstructionFormat != null) {
if (newInstructionFormat.equals(Format.Format30t)) {
modifiedInstruction = new ImmutableInstruction30t(Opcode.GOTO_32, newTargetOffset);
} else if (newInstructionFormat.equals(Format.Format20t)) {
modifiedInstruction = new ImmutableInstruction20t(Opcode.GOTO_16, newTargetOffset);
}
} else if (newTargetOffset != targetOffset) {
modifiedInstruction = new ImmutableInstruction10t(instr.getOpcode(), newTargetOffset);
}
break;
}
@ -229,12 +251,11 @@ public class InstructionWriteUtil {
Instruction20t instr = (Instruction20t)instruction;
int targetOffset = instr.getCodeOffset();
int newTargetOffset = targetOffset + targetOffsetShift(currentCodeOffset, targetOffset);
if (newTargetOffset != targetOffset) {
if ((short)newTargetOffset != newTargetOffset) {
modifiedInstruction = new ImmutableInstruction30t(Opcode.GOTO_32, newTargetOffset);
} else {
modifiedInstruction = new ImmutableInstruction20t(Opcode.GOTO_16, newTargetOffset);
}
Format newInstructionFormat = offsetToNewInstructionMap.get(currentCodeOffset);
if (newInstructionFormat != null && newInstructionFormat.equals(Format.Format30t)) {
modifiedInstruction = new ImmutableInstruction30t(Opcode.GOTO_32, newTargetOffset);
} else if (newTargetOffset != targetOffset) {
modifiedInstruction = new ImmutableInstruction20t(Opcode.GOTO_16, newTargetOffset);
}
break;
}
@ -321,7 +342,8 @@ public class InstructionWriteUtil {
}
private void alignPayload(int codeOffset) {
if (codeOffsetShifts.contains(codeOffset)) {
Format newInstructionFormat = offsetToNewInstructionMap.get(codeOffset);
if (newInstructionFormat != null && newInstructionFormat.equals(Format.Format10x)) {
instructions.add(new ImmutableInstruction10x(Opcode.NOP));
}
}