com.android.dx.ssa.SsaBasicBlock Java Examples

/**
 * Ensures that all the phi result registers for all the phis in the
 * same basic block interfere with each other, and also that a phi's source
 * registers interfere with the result registers from other phis. This is needed since
 * the dead code remover has allowed through "dead-end phis" whose
 * results are not used except as local assignments. Without this step,
 * a the result of a dead-end phi might be assigned the same register
 * as the result of another phi, and the phi removal move scheduler may
 * generate moves that over-write the live result.
 *
 * @param ssaMeth {@code non-null;} method to process
 * @param interference {@code non-null;} interference graph
 */
private static void coInterferePhis(SsaMethod ssaMeth,
        InterferenceGraph interference) {
    for (SsaBasicBlock b : ssaMeth.getBlocks()) {
        List<SsaInsn> phis = b.getPhiInsns();

        int szPhis = phis.size();

        for (int i = 0; i < szPhis; i++) {
            for (int j = 0; j < szPhis; j++) {
                if (i == j) {
                    continue;
                }

                SsaInsn first = phis.get(i);
                SsaInsn second = phis.get(j);
                coInterferePhiRegisters(interference, first.getResult(), second.getSources());
                coInterferePhiRegisters(interference, second.getResult(), first.getSources());
                interference.add(first.getResult().getReg(), second.getResult().getReg());
            }
        }
    }
}
 

/**
 * Ensures that all the phi result registers for all the phis in the
 * same basic block interfere with each other. This is needed since
 * the dead code remover has allowed through "dead-end phis" whose
 * results are not used except as local assignments. Without this step,
 * a the result of a dead-end phi might be assigned the same register
 * as the result of another phi, and the phi removal move scheduler may
 * generate moves that over-write the live result.
 *
 * @param ssaMeth {@code non-null;} method to pricess
 * @param interference {@code non-null;} interference graph
 */
private static void coInterferePhis(SsaMethod ssaMeth,
        InterferenceGraph interference) {
    for (SsaBasicBlock b : ssaMeth.getBlocks()) {
        List<SsaInsn> phis = b.getPhiInsns();

        int szPhis = phis.size();

        for (int i = 0; i < szPhis; i++) {
            for (int j = 0; j < szPhis; j++) {
                if (i == j) {
                    continue;
                }

                interference.add(phis.get(i).getResult().getReg(),
                    phis.get(j).getResult().getReg());
            }
        }
    }
}
 

/**
  * Removes all blocks containing only GOTOs from the control flow.
  * Although much of this work will be done later when converting
  * from rop to dex, not all simplification cases can be handled
  * there. Furthermore, any no-op block between the exit block and
  * blocks containing the real return or throw statements must be
  * removed.
  */
 private void removeEmptyGotos() {
     final ArrayList<SsaBasicBlock> blocks = ssaMeth.getBlocks();

     ssaMeth.forEachBlockDepthFirst(false, new SsaBasicBlock.Visitor() {
         @Override
public void visitBlock(SsaBasicBlock b, SsaBasicBlock parent) {
             ArrayList<SsaInsn> insns = b.getInsns();

             if ((insns.size() == 1)
                     && (insns.get(0).getOpcode() == Rops.GOTO)) {
                 BitSet preds = (BitSet) b.getPredecessors().clone();

                 for (int i = preds.nextSetBit(0); i >= 0;
                         i = preds.nextSetBit(i + 1)) {
                     SsaBasicBlock pb = blocks.get(i);
                     pb.replaceSuccessor(b.getIndex(),
                             b.getPrimarySuccessorIndex());
                 }
             }
         }
     });
 }
 

/**
 * Removes all blocks containing only GOTOs from the control flow.
 * Although much of this work will be done later when converting
 * from rop to dex, not all simplification cases can be handled
 * there. Furthermore, any no-op block between the exit block and
 * blocks containing the real return or throw statements must be
 * removed.
 */
private void removeEmptyGotos() {
    final ArrayList<SsaBasicBlock> blocks = ssaMeth.getBlocks();

    ssaMeth.forEachBlockDepthFirst(false, new SsaBasicBlock.Visitor() {
        @Override
        public void visitBlock(SsaBasicBlock b, SsaBasicBlock parent) {
            ArrayList<SsaInsn> insns = b.getInsns();

            if ((insns.size() == 1)
                    && (insns.get(0).getOpcode() == Rops.GOTO)) {
                BitSet preds = (BitSet) b.getPredecessors().clone();

                for (int i = preds.nextSetBit(0); i >= 0;
                        i = preds.nextSetBit(i + 1)) {
                    SsaBasicBlock pb = blocks.get(i);
                    pb.replaceSuccessor(b.getIndex(),
                            b.getPrimarySuccessorIndex());
                }
            }
        }
    });
}
 

/**
 * Ensures that all the phi result registers for all the phis in the
 * same basic block interfere with each other, and also that a phi's source
 * registers interfere with the result registers from other phis. This is needed since
 * the dead code remover has allowed through "dead-end phis" whose
 * results are not used except as local assignments. Without this step,
 * a the result of a dead-end phi might be assigned the same register
 * as the result of another phi, and the phi removal move scheduler may
 * generate moves that over-write the live result.
 *
 * @param ssaMeth {@code non-null;} method to process
 * @param interference {@code non-null;} interference graph
 */
private static void coInterferePhis(SsaMethod ssaMeth,
        InterferenceGraph interference) {
    for (SsaBasicBlock b : ssaMeth.getBlocks()) {
        List<SsaInsn> phis = b.getPhiInsns();

        int szPhis = phis.size();

        for (int i = 0; i < szPhis; i++) {
            for (int j = 0; j < szPhis; j++) {
                if (i == j) {
                    continue;
                }

                SsaInsn first = phis.get(i);
                SsaInsn second = phis.get(j);
                coInterferePhiRegisters(interference, first.getResult(), second.getSources());
                coInterferePhiRegisters(interference, second.getResult(), first.getSources());
                interference.add(first.getResult().getReg(), second.getResult().getReg());
            }
        }
    }
}
 

/**
 * Ensures that all the phi result registers for all the phis in the
 * same basic block interfere with each other. This is needed since
 * the dead code remover has allowed through "dead-end phis" whose
 * results are not used except as local assignments. Without this step,
 * a the result of a dead-end phi might be assigned the same register
 * as the result of another phi, and the phi removal move scheduler may
 * generate moves that over-write the live result.
 *
 * @param ssaMeth {@code non-null;} method to pricess
 * @param interference {@code non-null;} interference graph
 */
private static void coInterferePhis(SsaMethod ssaMeth,
        InterferenceGraph interference) {
    for (SsaBasicBlock b : ssaMeth.getBlocks()) {
        List<SsaInsn> phis = b.getPhiInsns();

        int szPhis = phis.size();

        for (int i = 0; i < szPhis; i++) {
            for (int j = 0; j < szPhis; j++) {
                if (i == j) {
                    continue;
                }

                interference.add(phis.get(i).getResult().getReg(),
                    phis.get(j).getResult().getReg());
            }
        }
    }
}
 

/**
 * Removes all blocks containing only GOTOs from the control flow.
 * Although much of this work will be done later when converting
 * from rop to dex, not all simplification cases can be handled
 * there. Furthermore, any no-op block between the exit block and
 * blocks containing the real return or throw statements must be
 * removed.
 */
private void removeEmptyGotos() {
    final ArrayList<SsaBasicBlock> blocks = ssaMeth.getBlocks();

    ssaMeth.forEachBlockDepthFirst(false, new SsaBasicBlock.Visitor() {
        public void visitBlock(SsaBasicBlock b, SsaBasicBlock parent) {
            ArrayList<SsaInsn> insns = b.getInsns();

            if ((insns.size() == 1)
                    && (insns.get(0).getOpcode() == Rops.GOTO)) {
                BitSet preds = (BitSet) b.getPredecessors().clone();

                for (int i = preds.nextSetBit(0); i >= 0;
                        i = preds.nextSetBit(i + 1)) {
                    SsaBasicBlock pb = blocks.get(i);
                    pb.replaceSuccessor(b.getIndex(),
                            b.getPrimarySuccessorIndex());
                }
            }
        }
    });
}
 

/**
 * Removes all blocks containing only GOTOs from the control flow.
 * Although much of this work will be done later when converting
 * from rop to dex, not all simplification cases can be handled
 * there. Furthermore, any no-op block between the exit block and
 * blocks containing the real return or throw statements must be
 * removed.
 */
private void removeEmptyGotos() {
    final ArrayList<SsaBasicBlock> blocks = ssaMeth.getBlocks();

    ssaMeth.forEachBlockDepthFirst(false, new SsaBasicBlock.Visitor() {
        @Override
        public void visitBlock(SsaBasicBlock b, SsaBasicBlock parent) {
            ArrayList<SsaInsn> insns = b.getInsns();

            if ((insns.size() == 1)
                    && (insns.get(0).getOpcode() == Rops.GOTO)) {
                BitSet preds = (BitSet) b.getPredecessors().clone();

                for (int i = preds.nextSetBit(0); i >= 0;
                        i = preds.nextSetBit(i + 1)) {
                    SsaBasicBlock pb = blocks.get(i);
                    pb.replaceSuccessor(b.getIndex(),
                            b.getPrimarySuccessorIndex());
                }
            }
        }
    });
}
 

public void visitPhiInsn(PhiInsn insn) {
    RegisterSpecList sources = insn.getSources();
    RegisterSpec result = insn.getResult();
    int sz = sources.size();

    for (int i = 0; i < sz; i++) {
        RegisterSpec source = sources.get(i);
        SsaBasicBlock predBlock = blocks.get(
                insn.predBlockIndexForSourcesIndex(i));

        predBlock.addMoveToEnd(result, source);
    }
}
 

/**
 * @return rop-form basic block list
 */
private BasicBlockList convertBasicBlocks() {
    ArrayList<SsaBasicBlock> blocks = ssaMeth.getBlocks();

    // Exit block may be null.
    SsaBasicBlock exitBlock = ssaMeth.getExitBlock();

    ssaMeth.computeReachability();
    int ropBlockCount = ssaMeth.getCountReachableBlocks();

    // Don't count the exit block, if it exists and is reachable.
    ropBlockCount -= (exitBlock != null && exitBlock.isReachable()) ? 1 : 0;

    BasicBlockList result = new BasicBlockList(ropBlockCount);

    // Convert all the reachable blocks except the exit block.
    int ropBlockIndex = 0;
    for (SsaBasicBlock b : blocks) {
        if (b.isReachable() && b != exitBlock) {
            result.set(ropBlockIndex++, convertBasicBlock(b));
        }
    }

    // The exit block, which is discarded, must do nothing.
    if (exitBlock != null && exitBlock.getInsns().size() != 0) {
        throw new RuntimeException(
                "Exit block must have no insns when leaving SSA form");
    }

    return result;
}
 

/**
 * From Appel algorithm 19.17.
 */
public void run() {
    List<SsaInsn> useList = ssaMeth.getUseListForRegister(regV);

    for (SsaInsn insn : useList) {
        nextFunction = NextFunction.DONE;

        if (insn instanceof PhiInsn) {
            // If s is a phi-function with V as it's ith argument.
            PhiInsn phi = (PhiInsn) insn;

            for (SsaBasicBlock pred :
                     phi.predBlocksForReg(regV, ssaMeth)) {
                blockN = pred;

                nextFunction = NextFunction.LIVE_OUT_AT_BLOCK;
                handleTailRecursion();
            }
        } else {
            blockN = insn.getBlock();
            statementIndex = blockN.getInsns().indexOf(insn);

            if (statementIndex < 0) {
                throw new RuntimeException(
                        "insn not found in it's own block");
            }

            nextFunction = NextFunction.LIVE_IN_AT_STATEMENT;
            handleTailRecursion();
        }
    }

    int nextLiveOutBlock;
    while ((nextLiveOutBlock = liveOutBlocks.nextSetBit(0)) >= 0) {
        blockN = ssaMeth.getBlocks().get(nextLiveOutBlock);
        liveOutBlocks.clear(nextLiveOutBlock);
        nextFunction = NextFunction.LIVE_OUT_AT_BLOCK;
        handleTailRecursion();
    }
}
 

/**
 * Validates that a basic block is a valid end predecessor. It must
 * end in a RETURN or a THROW. Throws a runtime exception on error.
 *
 * @param b {@code non-null;} block to validate
 * @throws RuntimeException on error
 */
private void verifyValidExitPredecessor(SsaBasicBlock b) {
    ArrayList<SsaInsn> insns = b.getInsns();
    SsaInsn lastInsn = insns.get(insns.size() - 1);
    Rop opcode = lastInsn.getOpcode();

    if (opcode.getBranchingness() != Rop.BRANCH_RETURN
            && opcode != Rops.THROW) {
        throw new RuntimeException("Exit predecessor must end"
                + " in valid exit statement.");
    }
}
 

/**
 * Converts a single basic block to rop form.
 *
 * @param block SSA block to process
 * @return {@code non-null;} ROP block
 */
private BasicBlock convertBasicBlock(SsaBasicBlock block) {
    IntList successorList = block.getRopLabelSuccessorList();
    int primarySuccessorLabel = block.getPrimarySuccessorRopLabel();

    // Filter out any reference to the SSA form's exit block.

    // Exit block may be null.
    SsaBasicBlock exitBlock = ssaMeth.getExitBlock();
    int exitRopLabel = (exitBlock == null) ? -1 : exitBlock.getRopLabel();

    if (successorList.contains(exitRopLabel)) {
        if (successorList.size() > 1) {
            throw new RuntimeException(
                    "Exit predecessor must have no other successors"
                            + Hex.u2(block.getRopLabel()));
        } else {
            successorList = IntList.EMPTY;
            primarySuccessorLabel = -1;

            verifyValidExitPredecessor(block);
        }
    }

    successorList.setImmutable();

    BasicBlock result = new BasicBlock(
            block.getRopLabel(), convertInsns(block.getInsns()),
            successorList,
            primarySuccessorLabel);

    return result;
}
 

/**
 * Validates that a basic block is a valid end predecessor. It must
 * end in a RETURN or a THROW. Throws a runtime exception on error.
 *
 * @param b {@code non-null;} block to validate
 * @throws RuntimeException on error
 */
private void verifyValidExitPredecessor(SsaBasicBlock b) {
    ArrayList<SsaInsn> insns = b.getInsns();
    SsaInsn lastInsn = insns.get(insns.size() - 1);
    Rop opcode = lastInsn.getOpcode();

    if (opcode.getBranchingness() != Rop.BRANCH_RETURN
            && opcode != Rops.THROW) {
        throw new RuntimeException("Exit predecessor must end"
                + " in valid exit statement.");
    }
}
 

/**
 * @return rop-form basic block list
 */
private BasicBlockList convertBasicBlocks() {
    ArrayList<SsaBasicBlock> blocks = ssaMeth.getBlocks();

    // Exit block may be null.
    SsaBasicBlock exitBlock = ssaMeth.getExitBlock();

    ssaMeth.computeReachability();
    int ropBlockCount = ssaMeth.getCountReachableBlocks();

    // Don't count the exit block, if it exists and is reachable.
    ropBlockCount -= (exitBlock != null && exitBlock.isReachable()) ? 1 : 0;

    BasicBlockList result = new BasicBlockList(ropBlockCount);

    // Convert all the reachable blocks except the exit block.
    int ropBlockIndex = 0;
    for (SsaBasicBlock b : blocks) {
        if (b.isReachable() && b != exitBlock) {
            result.set(ropBlockIndex++, convertBasicBlock(b));
        }
    }

    // The exit block, which is discarded, must do nothing.
    if (exitBlock != null && exitBlock.getInsns().size() != 0) {
        throw new RuntimeException(
                "Exit block must have no insns when leaving SSA form");
    }

    return result;
}
 

@Override
public void visitPhiInsn(PhiInsn insn) {
          RegisterSpecList sources = insn.getSources();
          RegisterSpec result = insn.getResult();
          int sz = sources.size();

          for (int i = 0; i < sz; i++) {
              RegisterSpec source = sources.get(i);
              SsaBasicBlock predBlock = blocks.get(
                      insn.predBlockIndexForSourcesIndex(i));

              predBlock.addMoveToEnd(result, source);
          }
      }
 

/**
 * From Appel algorithm 19.17.
 */
public void run() {
    List<SsaInsn> useList = ssaMeth.getUseListForRegister(regV);

    for (SsaInsn insn : useList) {
        nextFunction = NextFunction.DONE;

        if (insn instanceof PhiInsn) {
            // If s is a phi-function with V as it's ith argument.
            PhiInsn phi = (PhiInsn) insn;

            for (SsaBasicBlock pred :
                     phi.predBlocksForReg(regV, ssaMeth)) {
                blockN = pred;

                nextFunction = NextFunction.LIVE_OUT_AT_BLOCK;
                handleTailRecursion();
            }
        } else {
            blockN = insn.getBlock();
            statementIndex = blockN.getInsns().indexOf(insn);

            if (statementIndex < 0) {
                throw new RuntimeException(
                        "insn not found in it's own block");
            }

            nextFunction = NextFunction.LIVE_IN_AT_STATEMENT;
            handleTailRecursion();
        }
    }

    int nextLiveOutBlock;
    while ((nextLiveOutBlock = liveOutBlocks.nextSetBit(0)) >= 0) {
        blockN = ssaMeth.getBlocks().get(nextLiveOutBlock);
        liveOutBlocks.clear(nextLiveOutBlock);
        nextFunction = NextFunction.LIVE_OUT_AT_BLOCK;
        handleTailRecursion();
    }
}
 

/**
 * Converts a single basic block to rop form.
 *
 * @param block SSA block to process
 * @return {@code non-null;} ROP block
 */
private BasicBlock convertBasicBlock(SsaBasicBlock block) {
    IntList successorList = block.getRopLabelSuccessorList();
    int primarySuccessorLabel = block.getPrimarySuccessorRopLabel();

    // Filter out any reference to the SSA form's exit block.

    // Exit block may be null.
    SsaBasicBlock exitBlock = ssaMeth.getExitBlock();
    int exitRopLabel = (exitBlock == null) ? -1 : exitBlock.getRopLabel();

    if (successorList.contains(exitRopLabel)) {
        if (successorList.size() > 1) {
            throw new RuntimeException(
                    "Exit predecessor must have no other successors"
                            + Hex.u2(block.getRopLabel()));
        } else {
            successorList = IntList.EMPTY;
            primarySuccessorLabel = -1;

            verifyValidExitPredecessor(block);
        }
    }

    successorList.setImmutable();

    BasicBlock result = new BasicBlock(
            block.getRopLabel(), convertInsns(block.getInsns()),
            successorList,
            primarySuccessorLabel);

    return result;
}
 

/**
 * Converts a single basic block to rop form.
 *
 * @param block SSA block to process
 * @return {@code non-null;} ROP block
 */
private BasicBlock convertBasicBlock(SsaBasicBlock block) {
    IntList successorList = block.getRopLabelSuccessorList();
    int primarySuccessorLabel = block.getPrimarySuccessorRopLabel();

    // Filter out any reference to the SSA form's exit block.

    // Exit block may be null.
    SsaBasicBlock exitBlock = ssaMeth.getExitBlock();
    int exitRopLabel = (exitBlock == null) ? -1 : exitBlock.getRopLabel();

    if (successorList.contains(exitRopLabel)) {
        if (successorList.size() > 1) {
            throw new RuntimeException(
                    "Exit predecessor must have no other successors"
                            + Hex.u2(block.getRopLabel()));
        } else {
            successorList = IntList.EMPTY;
            primarySuccessorLabel = -1;

            verifyValidExitPredecessor(block);
        }
    }

    successorList.setImmutable();

    BasicBlock result = new BasicBlock(
            block.getRopLabel(), convertInsns(block.getInsns()),
            successorList,
            primarySuccessorLabel);

    return result;
}
 

@Override
public void visitPhiInsn(PhiInsn insn) {
    RegisterSpecList sources = insn.getSources();
    RegisterSpec result = insn.getResult();
    int sz = sources.size();

    for (int i = 0; i < sz; i++) {
        RegisterSpec source = sources.get(i);
        SsaBasicBlock predBlock = blocks.get(
                insn.predBlockIndexForSourcesIndex(i));

        predBlock.addMoveToEnd(result, source);
    }
}
 

/**
 * @return rop-form basic block list
 */
private BasicBlockList convertBasicBlocks() {
    ArrayList<SsaBasicBlock> blocks = ssaMeth.getBlocks();

    // Exit block may be null.
    SsaBasicBlock exitBlock = ssaMeth.getExitBlock();

    BitSet reachable = ssaMeth.computeReachability();
    int ropBlockCount = reachable.cardinality();

    // Don't count the exit block, if it exists and is reachable.
    if (exitBlock != null && reachable.get(exitBlock.getIndex())) {
        ropBlockCount -= 1;
    }

    BasicBlockList result = new BasicBlockList(ropBlockCount);

    // Convert all the reachable blocks except the exit block.
    int ropBlockIndex = 0;
    for (SsaBasicBlock b : blocks) {
        if (reachable.get(b.getIndex()) && b != exitBlock) {
            result.set(ropBlockIndex++, convertBasicBlock(b));
        }
    }

    // The exit block, which is discarded, must do nothing.
    if (exitBlock != null && !exitBlock.getInsns().isEmpty()) {
        throw new RuntimeException(
                "Exit block must have no insns when leaving SSA form");
    }

    return result;
}
 

/**
 * Validates that a basic block is a valid end predecessor. It must
 * end in a RETURN or a THROW. Throws a runtime exception on error.
 *
 * @param b {@code non-null;} block to validate
 * @throws RuntimeException on error
 */
private void verifyValidExitPredecessor(SsaBasicBlock b) {
    ArrayList<SsaInsn> insns = b.getInsns();
    SsaInsn lastInsn = insns.get(insns.size() - 1);
    Rop opcode = lastInsn.getOpcode();

    if (opcode.getBranchingness() != Rop.BRANCH_RETURN
            && opcode != Rops.THROW) {
        throw new RuntimeException("Exit predecessor must end"
                + " in valid exit statement.");
    }
}
 

/**
 * Converts a single basic block to rop form.
 *
 * @param block SSA block to process
 * @return {@code non-null;} ROP block
 */
private BasicBlock convertBasicBlock(SsaBasicBlock block) {
    IntList successorList = block.getRopLabelSuccessorList();
    int primarySuccessorLabel = block.getPrimarySuccessorRopLabel();

    // Filter out any reference to the SSA form's exit block.

    // Exit block may be null.
    SsaBasicBlock exitBlock = ssaMeth.getExitBlock();
    int exitRopLabel = (exitBlock == null) ? -1 : exitBlock.getRopLabel();

    if (successorList.contains(exitRopLabel)) {
        if (successorList.size() > 1) {
            throw new RuntimeException(
                    "Exit predecessor must have no other successors"
                            + Hex.u2(block.getRopLabel()));
        } else {
            successorList = IntList.EMPTY;
            primarySuccessorLabel = -1;

            verifyValidExitPredecessor(block);
        }
    }

    successorList.setImmutable();

    BasicBlock result = new BasicBlock(
            block.getRopLabel(), convertInsns(block.getInsns()),
            successorList,
            primarySuccessorLabel);

    return result;
}
 

/**
 * From Appel algorithm 19.17.
 */
public void run() {
    List<SsaInsn> useList = ssaMeth.getUseListForRegister(regV);

    for (SsaInsn insn : useList) {
        nextFunction = NextFunction.DONE;

        if (insn instanceof PhiInsn) {
            // If s is a phi-function with V as it's ith argument.
            PhiInsn phi = (PhiInsn) insn;

            for (SsaBasicBlock pred :
                     phi.predBlocksForReg(regV, ssaMeth)) {
                blockN = pred;

                nextFunction = NextFunction.LIVE_OUT_AT_BLOCK;
                handleTailRecursion();
            }
        } else {
            blockN = insn.getBlock();
            statementIndex = blockN.getInsns().indexOf(insn);

            if (statementIndex < 0) {
                throw new RuntimeException(
                        "insn not found in it's own block");
            }

            nextFunction = NextFunction.LIVE_IN_AT_STATEMENT;
            handleTailRecursion();
        }
    }

    int nextLiveOutBlock;
    while ((nextLiveOutBlock = liveOutBlocks.nextSetBit(0)) >= 0) {
        blockN = ssaMeth.getBlocks().get(nextLiveOutBlock);
        liveOutBlocks.clear(nextLiveOutBlock);
        nextFunction = NextFunction.LIVE_OUT_AT_BLOCK;
        handleTailRecursion();
    }
}
 

@Override
public void visitPhiInsn(PhiInsn insn) {
    RegisterSpecList sources = insn.getSources();
    RegisterSpec result = insn.getResult();
    int sz = sources.size();

    for (int i = 0; i < sz; i++) {
        RegisterSpec source = sources.get(i);
        SsaBasicBlock predBlock = blocks.get(
                insn.predBlockIndexForSourcesIndex(i));

        predBlock.addMoveToEnd(result, source);
    }
}
 

/**
 * @return rop-form basic block list
 */
private BasicBlockList convertBasicBlocks() {
    ArrayList<SsaBasicBlock> blocks = ssaMeth.getBlocks();

    // Exit block may be null.
    SsaBasicBlock exitBlock = ssaMeth.getExitBlock();

    BitSet reachable = ssaMeth.computeReachability();
    int ropBlockCount = reachable.cardinality();

    // Don't count the exit block, if it exists and is reachable.
    if (exitBlock != null && reachable.get(exitBlock.getIndex())) {
        ropBlockCount -= 1;
    }

    BasicBlockList result = new BasicBlockList(ropBlockCount);

    // Convert all the reachable blocks except the exit block.
    int ropBlockIndex = 0;
    for (SsaBasicBlock b : blocks) {
        if (reachable.get(b.getIndex()) && b != exitBlock) {
            result.set(ropBlockIndex++, convertBasicBlock(b));
        }
    }

    // The exit block, which is discarded, must do nothing.
    if (exitBlock != null && !exitBlock.getInsns().isEmpty()) {
        throw new RuntimeException(
                "Exit block must have no insns when leaving SSA form");
    }

    return result;
}
 

/**
 * Validates that a basic block is a valid end predecessor. It must
 * end in a RETURN or a THROW. Throws a runtime exception on error.
 *
 * @param b {@code non-null;} block to validate
 * @throws RuntimeException on error
 */
private void verifyValidExitPredecessor(SsaBasicBlock b) {
    ArrayList<SsaInsn> insns = b.getInsns();
    SsaInsn lastInsn = insns.get(insns.size() - 1);
    Rop opcode = lastInsn.getOpcode();

    if (opcode.getBranchingness() != Rop.BRANCH_RETURN
            && opcode != Rops.THROW) {
        throw new RuntimeException("Exit predecessor must end"
                + " in valid exit statement.");
    }
}
 

/**
 * From Appel algorithm 19.17.
 */
public void run() {
    List<SsaInsn> useList = ssaMeth.getUseListForRegister(regV);

    for (SsaInsn insn : useList) {
        nextFunction = NextFunction.DONE;

        if (insn instanceof PhiInsn) {
            // If s is a phi-function with V as it's ith argument.
            PhiInsn phi = (PhiInsn) insn;

            for (SsaBasicBlock pred :
                     phi.predBlocksForReg(regV, ssaMeth)) {
                blockN = pred;

                nextFunction = NextFunction.LIVE_OUT_AT_BLOCK;
                handleTailRecursion();
            }
        } else {
            blockN = insn.getBlock();
            statementIndex = blockN.getInsns().indexOf(insn);

            if (statementIndex < 0) {
                throw new RuntimeException(
                        "insn not found in it's own block");
            }

            nextFunction = NextFunction.LIVE_IN_AT_STATEMENT;
            handleTailRecursion();
        }
    }

    int nextLiveOutBlock;
    while ((nextLiveOutBlock = liveOutBlocks.nextSetBit(0)) >= 0) {
        blockN = ssaMeth.getBlocks().get(nextLiveOutBlock);
        liveOutBlocks.clear(nextLiveOutBlock);
        nextFunction = NextFunction.LIVE_OUT_AT_BLOCK;
        handleTailRecursion();
    }
}
 

public PhiVisitor(ArrayList<SsaBasicBlock> blocks) {
    this.blocks = blocks;
}
 

/**
 * Inserts a move instruction for a specified SSA register before a
 * specified instruction, creating a new SSA register and adjusting the
 * interference graph in the process. The insn currently must be the
 * last insn in a block.
 *
 * @param insn {@code non-null;} insn to insert move before, must
 * be last insn in block
 * @param reg {@code non-null;} SSA register to duplicate
 * @return {@code non-null;} spec of new SSA register created by move
 */
protected final RegisterSpec insertMoveBefore(SsaInsn insn,
        RegisterSpec reg) {
    SsaBasicBlock block = insn.getBlock();
    ArrayList<SsaInsn> insns = block.getInsns();
    int insnIndex = insns.indexOf(insn);

    if (insnIndex < 0) {
        throw new IllegalArgumentException (
                "specified insn is not in this block");
    }

    if (insnIndex != insns.size() - 1) {
        /*
         * Presently, the interference updater only works when
         * adding before the last insn, and the last insn must have no
         * result
         */
        throw new IllegalArgumentException(
                "Adding move here not supported:" + insn.toHuman());
    }

    /*
     * Get new register and make new move instruction.
     */

    // The new result must not have an associated local variable.
    RegisterSpec newRegSpec = RegisterSpec.make(ssaMeth.makeNewSsaReg(),
            reg.getTypeBearer());

    SsaInsn toAdd = SsaInsn.makeFromRop(
            new PlainInsn(Rops.opMove(newRegSpec.getType()),
                    SourcePosition.NO_INFO, newRegSpec,
                    RegisterSpecList.make(reg)), block);

    insns.add(insnIndex, toAdd);

    int newReg = newRegSpec.getReg();

    /*
     * Adjust interference graph based on what's live out of the current
     * block and what's used by the final instruction.
     */

    IntSet liveOut = block.getLiveOutRegs();
    IntIterator liveOutIter = liveOut.iterator();

    while (liveOutIter.hasNext()) {
        interference.add(newReg, liveOutIter.next());
    }

    // Everything that's a source in the last insn interferes.
    RegisterSpecList sources = insn.getSources();
    int szSources = sources.size();

    for (int i = 0; i < szSources; i++) {
        interference.add(newReg, sources.get(i).getReg());
    }

    ssaMeth.onInsnsChanged();

    return newRegSpec;
}