FileDocCategorySizeDatePackage
DebugInfoEncoder.javaAPI DocAndroid 5.1 API29768Thu Mar 12 22:18:30 GMT 2015com.android.dexgen.dex.file

DebugInfoEncoder

public final class DebugInfoEncoder extends Object
An encoder for the dex debug info state machine format. The format for each method enrty is as follows:
  1. signed LEB128: initial value for line register.
  2. n instances of signed LEB128: string indicies (offset by 1) for each method argument in left-to-right order with {@code this} excluded. A value of '0' indicates "no name"
  3. A sequence of special or normal opcodes as defined in {@code DebugInfoConstants}.
  4. A single terminating {@code OP_END_SEQUENCE}

Fields Summary
private static final boolean
DEBUG
private final com.android.dexgen.dex.code.PositionList
positions
{@code null-ok;} positions (line numbers) to encode
private final com.android.dexgen.dex.code.LocalList
locals
{@code null-ok;} local variables to encode
private final com.android.dexgen.util.ByteArrayAnnotatedOutput
output
private final DexFile
file
private final int
codeSize
private final int
regSize
private final com.android.dexgen.rop.type.Prototype
desc
private final boolean
isStatic
private int
address
current encoding state: bytecode address
private int
line
current encoding state: line number
private com.android.dexgen.util.AnnotatedOutput
annotateTo
if non-null: the output to write annotations to. No normal output is written to this.
private PrintWriter
debugPrint
if non-null: another possible output for annotations
private String
prefix
if non-null: the prefix for each annotation or debugPrint line
private boolean
shouldConsume
true if output should be consumed during annotation
private final LocalList.Entry[]
lastEntryForReg
indexed by register; last local alive in register
Constructors Summary
public DebugInfoEncoder(com.android.dexgen.dex.code.PositionList positions, com.android.dexgen.dex.code.LocalList locals, DexFile file, int codeSize, int regSize, boolean isStatic, com.android.dexgen.rop.cst.CstMethodRef ref)
Creates an instance.

param
positions {@code null-ok;} positions (line numbers) to encode
param
locals {@code null-ok;} local variables to encode
param
file {@code null-ok;} may only be {@code null} if simply using this class to do a debug print
param
codeSize
param
regSize
param
isStatic
param
ref


                                                        
        
                 
                
        this.positions = positions;
        this.locals = locals;
        this.file = file;
        this.desc = ref.getPrototype();
        this.isStatic = isStatic;
        this.codeSize = codeSize;
        this.regSize = regSize;

        output = new ByteArrayAnnotatedOutput();
        lastEntryForReg = new LocalList.Entry[regSize];
Methods Summary
private voidannotate(int length, java.lang.String message)
Annotates or writes a message to the {@code debugPrint} writer if applicable.

param
length the number of bytes associated with this message
param
message the message itself

        if (prefix != null) {
            message = prefix + message;
        }

        if (annotateTo != null) {
            annotateTo.annotate(shouldConsume ? length : 0, message);
        }

        if (debugPrint != null) {
            debugPrint.println(message);
        }
private java.util.ArrayListbuildSortedPositions()
Builds a list of position entries, sorted by ascending address.

return
A sorted positions list

        int sz = (positions == null) ? 0 : positions.size();
        ArrayList<PositionList.Entry> result = new ArrayList(sz);

        for (int i = 0; i < sz; i++) {
            result.add(positions.get(i));
        }

        // Sort ascending by address.
        Collections.sort (result, new Comparator<PositionList.Entry>() {
            public int compare (PositionList.Entry a, PositionList.Entry b) {
                return a.getAddress() - b.getAddress();
            }

            public boolean equals (Object obj) {
               return obj == this;
            }
        });
        return result;
private static intcomputeOpcode(int deltaLines, int deltaAddress)
Computes a special opcode that will encode the given position change. If the return value is > 0xff, then the request cannot be fulfilled. Essentially the same as described in "DWARF Debugging Format Version 3" section 6.2.5.1.

param
deltaLines {@code >= DBG_LINE_BASE, <= DBG_LINE_BASE + DBG_LINE_RANGE;} the line change to encode
param
deltaAddress {@code >= 0;} the address change to encode
return
{@code <= 0xff} if in range, otherwise parameters are out of range

        if (deltaLines < DBG_LINE_BASE
                || deltaLines > (DBG_LINE_BASE + DBG_LINE_RANGE -1)) {

            throw new RuntimeException("Parameter out of range");
        }

        return (deltaLines - DBG_LINE_BASE)
            + (DBG_LINE_RANGE * deltaAddress) + DBG_FIRST_SPECIAL;
public byte[]convert()
Converts this (PositionList, LocalList) pair into a state machine sequence.

return
{@code non-null;} encoded byte sequence without padding and terminated with a {@code 0x00} byte

        try {
            byte[] ret;
            ret = convert0();

            if (DEBUG) {
                for (int i = 0 ; i < ret.length; i++) {
                    System.err.printf("byte %02x\n", (0xff & ret[i]));
                }
            }

            return ret;
        } catch (IOException ex) {
            throw ExceptionWithContext
                    .withContext(ex, "...while encoding debug info");
        }
private byte[]convert0()

        ArrayList<PositionList.Entry> sortedPositions = buildSortedPositions();
        ArrayList<LocalList.Entry> methodArgs = extractMethodArguments();

        emitHeader(sortedPositions, methodArgs);

        // TODO: Make this mark be the actual prologue end.
        output.writeByte(DBG_SET_PROLOGUE_END);

        if (annotateTo != null || debugPrint != null) {
            annotate(1, String.format("%04x: prologue end",address));
        }

        int positionsSz = sortedPositions.size();
        int localsSz = locals.size();

        // Current index in sortedPositions
        int curPositionIdx = 0;
        // Current index in locals
        int curLocalIdx = 0;

        for (;;) {
            /*
             * Emit any information for the current address.
             */

            curLocalIdx = emitLocalsAtAddress(curLocalIdx);
            curPositionIdx =
                emitPositionsAtAddress(curPositionIdx, sortedPositions);

            /*
             * Figure out what the next important address is.
             */

            int nextAddrL = Integer.MAX_VALUE; // local variable
            int nextAddrP = Integer.MAX_VALUE; // position (line number)

            if (curLocalIdx < localsSz) {
                nextAddrL = locals.get(curLocalIdx).getAddress();
            }

            if (curPositionIdx < positionsSz) {
                nextAddrP = sortedPositions.get(curPositionIdx).getAddress();
            }

            int next = Math.min(nextAddrP, nextAddrL);

            // No next important address == done.
            if (next == Integer.MAX_VALUE) {
                break;
            }

            /*
             * If the only work remaining are local ends at the end of the
             * block, stop here. Those are implied anyway.
             */
            if (next == codeSize
                    && nextAddrL == Integer.MAX_VALUE
                    && nextAddrP == Integer.MAX_VALUE) {
                break;
            }

            if (next == nextAddrP) {
                // Combined advance PC + position entry
                emitPosition(sortedPositions.get(curPositionIdx++));
            } else {
                emitAdvancePc(next - address);
            }
        }

        emitEndSequence();

        return output.toByteArray();
public byte[]convertAndAnnotate(java.lang.String prefix, java.io.PrintWriter debugPrint, com.android.dexgen.util.AnnotatedOutput out, boolean consume)
Converts and produces annotations on a stream. Does not write actual bits to the {@code AnnotatedOutput}.

param
prefix {@code null-ok;} prefix to attach to each line of output
param
debugPrint {@code null-ok;} if specified, an alternate output for annotations
param
out {@code null-ok;} if specified, where annotations should go
param
consume whether to claim to have consumed output for {@code out}
return
{@code non-null;} encoded output

        this.prefix = prefix;
        this.debugPrint = debugPrint;
        annotateTo = out;
        shouldConsume = consume;

        byte[] result = convert();

        return result;
private voidemitAdvanceLine(int deltaLines)
Emits an {@link DebugInfoConstants#DBG_ADVANCE_LINE DBG_ADVANCE_LINE} sequence.

param
deltaLines amount to change line number register by
throws
IOException

        int mark = output.getCursor();

        output.writeByte(DBG_ADVANCE_LINE);
        output.writeSignedLeb128(deltaLines);
        line += deltaLines;

        if (annotateTo != null || debugPrint != null) {
            annotate(output.getCursor() - mark,
                    String.format("line = %d", line));
        }

        if (DEBUG) {
            System.err.printf("Emitting advance_line for %d\n", deltaLines);
        }
private voidemitAdvancePc(int deltaAddress)
Emits an {@link DebugInfoConstants#DBG_ADVANCE_PC DBG_ADVANCE_PC} sequence.

param
deltaAddress {@code >= 0;} amount to change program counter by
throws
IOException

        int mark = output.getCursor();

        output.writeByte(DBG_ADVANCE_PC);
        output.writeUnsignedLeb128(deltaAddress);
        address += deltaAddress;

        if (annotateTo != null || debugPrint != null) {
            annotate(output.getCursor() - mark,
                    String.format("%04x: advance pc", address));
        }

        if (DEBUG) {
            System.err.printf("Emitting advance_pc for %d\n", deltaAddress);
        }
private voidemitEndSequence()
Emits the {@link DebugInfoConstants#DBG_END_SEQUENCE DBG_END_SEQUENCE} bytecode.

        output.writeByte(DBG_END_SEQUENCE);

        if (annotateTo != null || debugPrint != null) {
            annotate(1, "end sequence");
        }
private voidemitHeader(java.util.ArrayList sortedPositions, java.util.ArrayList methodArgs)
Emits the header sequence, which consists of LEB128-encoded initial line number and string indicies for names of all non-"this" arguments.

param
sortedPositions positions, sorted by ascending address
param
methodArgs local list entries for method argumens arguments, in left-to-right order omitting "this"
throws
IOException

        boolean annotate = (annotateTo != null) || (debugPrint != null);
        int mark = output.getCursor();

        // Start by initializing the line number register.
        if (sortedPositions.size() > 0) {
            PositionList.Entry entry = sortedPositions.get(0);
            line = entry.getPosition().getLine();
        }
        output.writeUnsignedLeb128(line);

        if (annotate) {
            annotate(output.getCursor() - mark, "line_start: " + line);
        }

        int curParam = getParamBase();
        // paramTypes will not include 'this'
        StdTypeList paramTypes = desc.getParameterTypes();
        int szParamTypes = paramTypes.size();

        /*
         * Initialize lastEntryForReg to have an initial
         * entry for the 'this' pointer.
         */
        if (!isStatic) {
            for (LocalList.Entry arg : methodArgs) {
                if (curParam == arg.getRegister()) {
                    lastEntryForReg[curParam] = arg;
                    break;
                }
            }
            curParam++;
        }

        // Write out the number of parameter entries that will follow.
        mark = output.getCursor();
        output.writeUnsignedLeb128(szParamTypes);

        if (annotate) {
            annotate(output.getCursor() - mark,
                    String.format("parameters_size: %04x", szParamTypes));
        }

        /*
         * Then emit the string indicies of all the method parameters.
         * Note that 'this', if applicable, is excluded.
         */
        for (int i = 0; i < szParamTypes; i++) {
            Type pt = paramTypes.get(i);
            LocalList.Entry found = null;

            mark = output.getCursor();

            for (LocalList.Entry arg : methodArgs) {
                if (curParam == arg.getRegister()) {
                    found = arg;

                    if (arg.getSignature() != null) {
                        /*
                         * Parameters with signatures will be re-emitted
                         * in complete as LOCAL_START_EXTENDED's below.
                         */
                        emitStringIndex(null);
                    } else {
                        emitStringIndex(arg.getName());
                    }
                    lastEntryForReg[curParam] = arg;

                    break;
                }
            }

            if (found == null) {
                /*
                 * Emit a null symbol for "unnamed." This is common
                 * for, e.g., synthesized methods and inner-class
                 * this$0 arguments.
                 */
                emitStringIndex(null);
            }

            if (annotate) {
                String parameterName
                        = (found == null || found.getSignature() != null)
                                ? "<unnamed>" : found.getName().toHuman();
                annotate(output.getCursor() - mark,
                        "parameter " + parameterName + " "
                                + RegisterSpec.PREFIX + curParam);
            }

            curParam += pt.getCategory();
        }

        /*
         * If anything emitted above has a type signature, emit it again as
         * a LOCAL_RESTART_EXTENDED
         */

        for (LocalList.Entry arg : lastEntryForReg) {
            if (arg == null) {
                continue;
            }

            CstUtf8 signature = arg.getSignature();

            if (signature != null) {
                emitLocalStartExtended(arg);
            }
        }
private voidemitLocalEnd(LocalList.Entry entry)
Emits a {@link DebugInfoConstants#DBG_END_LOCAL DBG_END_LOCAL} sequence.

param
entry {@code entry non-null;} entry associated with end.
throws
IOException


        int mark = output.getCursor();

        output.writeByte(DBG_END_LOCAL);
        output.writeUnsignedLeb128(entry.getRegister());

        if (annotateTo != null || debugPrint != null) {
            annotate(output.getCursor() - mark,
                    String.format("%04x: -local %s", address,
                            entryAnnotationString(entry)));
        }

        if (DEBUG) {
            System.err.println("emit local end");
        }
private voidemitLocalRestart(LocalList.Entry entry)
Emits a {@link DebugInfoConstants#DBG_RESTART_LOCAL DBG_RESTART_LOCAL} sequence.

param
entry entry associated with this restart
throws
IOException


        int mark = output.getCursor();

        output.writeByte(DBG_RESTART_LOCAL);
        emitUnsignedLeb128(entry.getRegister());

        if (annotateTo != null || debugPrint != null) {
            annotate(output.getCursor() - mark,
                    String.format("%04x: +local restart %s",
                            address, entryAnnotationString(entry)));
        }

        if (DEBUG) {
            System.err.println("emit local restart");
        }
private voidemitLocalStart(LocalList.Entry entry)
Emits a {@link DebugInfoConstants#DBG_START_LOCAL DBG_START_LOCAL} or {@link DebugInfoConstants#DBG_START_LOCAL_EXTENDED DBG_START_LOCAL_EXTENDED} sequence.

param
entry entry to emit
throws
IOException


        if (entry.getSignature() != null) {
            emitLocalStartExtended(entry);
            return;
        }

        int mark = output.getCursor();

        output.writeByte(DBG_START_LOCAL);

        emitUnsignedLeb128(entry.getRegister());
        emitStringIndex(entry.getName());
        emitTypeIndex(entry.getType());

        if (annotateTo != null || debugPrint != null) {
            annotate(output.getCursor() - mark,
                    String.format("%04x: +local %s", address,
                            entryAnnotationString(entry)));
        }

        if (DEBUG) {
            System.err.println("emit local start");
        }
private voidemitLocalStartExtended(LocalList.Entry entry)
Emits a {@link DebugInfoConstants#DBG_START_LOCAL_EXTENDED DBG_START_LOCAL_EXTENDED} sequence.

param
entry entry to emit
throws
IOException


        int mark = output.getCursor();

        output.writeByte(DBG_START_LOCAL_EXTENDED);

        emitUnsignedLeb128(entry.getRegister());
        emitStringIndex(entry.getName());
        emitTypeIndex(entry.getType());
        emitStringIndex(entry.getSignature());

        if (annotateTo != null || debugPrint != null) {
            annotate(output.getCursor() - mark,
                    String.format("%04x: +localx %s", address,
                            entryAnnotationString(entry)));
        }

        if (DEBUG) {
            System.err.println("emit local start");
        }
private intemitLocalsAtAddress(int curLocalIdx)
Emits all local variable activity that occurs at the current {@link #address} starting at the given index into {@code locals} and including all subsequent activity at the same address.

param
curLocalIdx Current index in locals
return
new value for {@code curLocalIdx}
throws
IOException

        int sz = locals.size();

        // TODO: Don't emit ends implied by starts.

        while ((curLocalIdx < sz)
                && (locals.get(curLocalIdx).getAddress() == address)) {
            LocalList.Entry entry = locals.get(curLocalIdx++);
            int reg = entry.getRegister();
            LocalList.Entry prevEntry = lastEntryForReg[reg];

            if (entry == prevEntry) {
                /*
                 * Here we ignore locals entries for parameters,
                 * which have already been represented and placed in the
                 * lastEntryForReg array.
                 */
                continue;
            }

            // At this point we have a new entry one way or another.
            lastEntryForReg[reg] = entry;

            if (entry.isStart()) {
                if ((prevEntry != null) && entry.matches(prevEntry)) {
                    /*
                     * The previous local in this register has the same
                     * name and type as the one being introduced now, so
                     * use the more efficient "restart" form.
                     */
                    if (prevEntry.isStart()) {
                        /*
                         * We should never be handed a start when a
                         * a matching local is already active.
                         */
                        throw new RuntimeException("shouldn't happen");
                    }
                    emitLocalRestart(entry);
                } else {
                    emitLocalStart(entry);
                }
            } else {
                /*
                 * Only emit a local end if it is *not* due to a direct
                 * replacement. Direct replacements imply an end of the
                 * previous local in the same register.
                 *
                 * TODO: Make sure the runtime can deal with implied
                 * local ends from category-2 interactions, and when so,
                 * also stop emitting local ends for those cases.
                 */
                if (entry.getDisposition()
                        != LocalList.Disposition.END_REPLACED) {
                    emitLocalEnd(entry);
                }
            }
        }

        return curLocalIdx;
private voidemitPosition(PositionList.Entry entry)
Emits the necessary byte sequences to emit the given position table entry. This will typically be a single special opcode, although it may also require DBG_ADVANCE_PC or DBG_ADVANCE_LINE.

param
entry position entry to emit.
throws
IOException


        SourcePosition pos = entry.getPosition();
        int newLine = pos.getLine();
        int newAddress = entry.getAddress();

        int opcode;

        int deltaLines = newLine - line;
        int deltaAddress = newAddress - address;

        if (deltaAddress < 0) {
            throw new RuntimeException(
                    "Position entries must be in ascending address order");
        }

        if ((deltaLines < DBG_LINE_BASE)
                || (deltaLines > (DBG_LINE_BASE + DBG_LINE_RANGE -1))) {
            emitAdvanceLine(deltaLines);
            deltaLines = 0;
        }

        opcode = computeOpcode (deltaLines, deltaAddress);

        if ((opcode & ~0xff) > 0) {
            emitAdvancePc(deltaAddress);
            deltaAddress = 0;
            opcode = computeOpcode (deltaLines, deltaAddress);

            if ((opcode & ~0xff) > 0) {
                emitAdvanceLine(deltaLines);
                deltaLines = 0;
                opcode = computeOpcode (deltaLines, deltaAddress);
            }
        }

        output.writeByte(opcode);

        line += deltaLines;
        address += deltaAddress;

        if (annotateTo != null || debugPrint != null) {
            annotate(1,
                    String.format("%04x: line %d", address, line));
        }
private intemitPositionsAtAddress(int curPositionIdx, java.util.ArrayList sortedPositions)
Emits all positions that occur at the current {@code address}

param
curPositionIdx Current index in sortedPositions
param
sortedPositions positions, sorted by ascending address
return
new value for {@code curPositionIdx}
throws
IOException

        int positionsSz = sortedPositions.size();
        while ((curPositionIdx < positionsSz)
                && (sortedPositions.get(curPositionIdx).getAddress()
                        == address)) {
            emitPosition(sortedPositions.get(curPositionIdx++));
        }
        return curPositionIdx;
private voidemitStringIndex(com.android.dexgen.rop.cst.CstUtf8 string)
Emits a string index as an unsigned LEB128. The actual value written is shifted by 1, so that the '0' value is reserved for "null". The null symbol is used in some cases by the parameter name list at the beginning of the sequence.

param
string {@code null-ok;} string to emit
throws
IOException

        if ((string == null) || (file == null)) {
            output.writeUnsignedLeb128(0);
        } else {
            output.writeUnsignedLeb128(
                1 + file.getStringIds().indexOf(string));
        }

        if (DEBUG) {
            System.err.printf("Emit string %s\n",
                    string == null ? "<null>" : string.toQuoted());
        }
private voidemitTypeIndex(com.android.dexgen.rop.cst.CstType type)
Emits a type index as an unsigned LEB128. The actual value written is shifted by 1, so that the '0' value is reserved for "null".

param
type {@code null-ok;} type to emit
throws
IOException

        if ((type == null) || (file == null)) {
            output.writeUnsignedLeb128(0);
        } else {
            output.writeUnsignedLeb128(
                1 + file.getTypeIds().indexOf(type));
        }

        if (DEBUG) {
            System.err.printf("Emit type %s\n",
                    type == null ? "<null>" : type.toHuman());
        }
private voidemitUnsignedLeb128(int n)
Emits an unsigned LEB128 value.

param
n {@code >= 0;} value to emit. Note that, although this can represent integers larger than Integer.MAX_VALUE, we currently don't allow that.
throws
IOException

        // We'll never need the top end of the unsigned range anyway.
        if (n < 0) {
            throw new RuntimeException(
                    "Signed value where unsigned required: " + n);
        }

        output.writeUnsignedLeb128(n);
private java.lang.StringentryAnnotationString(LocalList.Entry e)
Returns a string representation of this LocalList entry that is appropriate for emitting as an annotation.

param
e {@code non-null;} entry
return
{@code non-null;} annotation string

        StringBuilder sb = new StringBuilder();

        sb.append(RegisterSpec.PREFIX);
        sb.append(e.getRegister());
        sb.append(' ");

        CstUtf8 name = e.getName();
        if (name == null) {
            sb.append("null");
        } else {
            sb.append(name.toHuman());
        }
        sb.append(' ");

        CstType type = e.getType();
        if (type == null) {
            sb.append("null");
        } else {
            sb.append(type.toHuman());
        }

        CstUtf8 signature = e.getSignature();

        if (signature != null) {
            sb.append(' ");
            sb.append(signature.toHuman());
        }

        return sb.toString();
private java.util.ArrayListextractMethodArguments()
Extracts method arguments from a locals list. These will be collected from the input list and sorted by ascending register in the returned list.

return
list of non-{@code this} method argument locals, sorted by ascending register

        ArrayList<LocalList.Entry> result
                = new ArrayList(desc.getParameterTypes().size());
        int argBase = getParamBase();
        BitSet seen = new BitSet(regSize - argBase);
        int sz = locals.size();

        for (int i = 0; i < sz; i++) {
            LocalList.Entry e = locals.get(i);
            int reg = e.getRegister();

            if (reg < argBase) {
                continue;
            }

            // only the lowest-start-address entry is included.
            if (seen.get(reg - argBase)) {
                continue;
            }

            seen.set(reg - argBase);
            result.add(e);
        }

        // Sort by ascending register.
        Collections.sort(result, new Comparator<LocalList.Entry>() {
            public int compare(LocalList.Entry a, LocalList.Entry b) {
                return a.getRegister() - b.getRegister();
            }

            public boolean equals(Object obj) {
               return obj == this;
            }
        });

        return result;
private intgetParamBase()
Gets the register that begins the method's parameter range (including the 'this' parameter for non-static methods). The range continues until {@code regSize}

return
register as noted above

        return regSize
                - desc.getParameterTypes().getWordCount() - (isStatic? 0 : 1);