classreader.java

linux下建立JAVA虚拟机的源码KAFFE

        } else if (attrName.equals("Synthetic")) {
          access |= Constants.ACC_SYNTHETIC;
        } else if (attrName.equals("Deprecated")) {
          access |= Constants.ACC_DEPRECATED;
        } else {
          attr = readAttribute(
            attrs, attrName, u + 6, readInt(u + 2), c, -1, null);
          if (attr != null) {
            attr.next = fattrs;
            fattrs = attr;
          }
        }
        u += 6 + readInt(u + 2);
      }
      // reads the field's value, if any
      Object value = (fieldValueItem == 0 ? null : readConst(fieldValueItem, c));
      // visits the field
      classVisitor.visitField(access, fieldName, fieldDesc, value, fattrs);
    }

    // visits the methods
    i = readUnsignedShort(u); u += 2;
    for ( ; i > 0; --i) {
      access = readUnsignedShort(u);
      String methName = readUTF8(u + 2, c);
      String methDesc = readUTF8(u + 4, c);
      Attribute mattrs = null;
      Attribute cattrs = null;
      v = 0;
      w = 0;
      // looks for Code and Exceptions attributes
      j = readUnsignedShort(u + 6);
      u += 8;
      for ( ; j > 0; --j) {
        String attrName = readUTF8(u, c); u += 2;
        int attrSize = readInt(u); u += 4;
        if (attrName.equals("Code")) {
          v = u;
        } else if (attrName.equals("Exceptions")) {
          w = u;
        } else if (attrName.equals("Synthetic")) {
          access |= Constants.ACC_SYNTHETIC;
        } else if (attrName.equals("Deprecated")) {
          access |= Constants.ACC_DEPRECATED;
        } else {
          attr = readAttribute(attrs, attrName, u, attrSize, c, -1, null);
          if (attr != null) {
            attr.next = mattrs;
            mattrs = attr;
          }
        }
        u += attrSize;
      }
      // reads declared exceptions
      String[] exceptions;
      if (w == 0) {
        exceptions = null;
      } else {
        exceptions = new String[readUnsignedShort(w)]; w += 2;
        for (j = 0; j < exceptions.length; ++j) {
          exceptions[j] = readClass(w, c); w += 2;
        }
      }

      // visits the method's code, if any
      CodeVisitor cv;
      cv = classVisitor.visitMethod(
        access, methName, methDesc, exceptions, mattrs);
      if (cv != null && v != 0) {
        int maxStack = readUnsignedShort(v);
        int maxLocals = readUnsignedShort(v + 2);
        int codeLength = readInt(v + 4);
        v += 8;

        int codeStart = v;
        int codeEnd = v + codeLength;

        // 1st phase: finds the labels
        int label;
        Label[] labels = new Label[codeLength + 1];
        while (v < codeEnd) {
          int opcode = b[v] & 0xFF;
          switch (ClassWriter.TYPE[opcode]) {
            case ClassWriter.NOARG_INSN:
            case ClassWriter.IMPLVAR_INSN:
              v += 1;
              break;
            case ClassWriter.LABEL_INSN:
              label = v - codeStart + readShort(v + 1);
              if (labels[label] == null) {
                labels[label] = new Label();
              }
              v += 3;
              break;
            case ClassWriter.LABELW_INSN:
              label = v - codeStart + readInt(v + 1);
              if (labels[label] == null) {
                labels[label] = new Label();
              }
              v += 5;
              break;
            case ClassWriter.WIDE_INSN:
              opcode = b[v + 1] & 0xFF;
              if (opcode == Constants.IINC) {
                v += 6;
              } else {
                v += 4;
              }
              break;
            case ClassWriter.TABL_INSN:
              // skips 0 to 3 padding bytes
              w = v - codeStart;
              v = v + 4 - (w & 3);
              // reads instruction
              label = w + readInt(v); v += 4;
              if (labels[label] == null) {
                labels[label] = new Label();
              }
              j = readInt(v); v += 4;
              j = readInt(v) - j + 1; v += 4;
              for ( ; j > 0; --j) {
                label = w + readInt(v); v += 4;
                if (labels[label] == null) {
                  labels[label] = new Label();
                }
              }
              break;
            case ClassWriter.LOOK_INSN:
              // skips 0 to 3 padding bytes
              w = v - codeStart;
              v = v + 4 - (w & 3);
              // reads instruction
              label = w + readInt(v); v += 4;
              if (labels[label] == null) {
                labels[label] = new Label();
              }
              j = readInt(v); v += 4;
              for ( ; j > 0; --j) {
                v += 4; // skips key
                label = w + readInt(v); v += 4;
                if (labels[label] == null) {
                  labels[label] = new Label();
                }
              }
              break;
            case ClassWriter.VAR_INSN:
            case ClassWriter.SBYTE_INSN:
            case ClassWriter.LDC_INSN:
              v += 2;
              break;
            case ClassWriter.SHORT_INSN:
            case ClassWriter.LDCW_INSN:
            case ClassWriter.FIELDORMETH_INSN:
            case ClassWriter.TYPE_INSN:
            case ClassWriter.IINC_INSN:
              v += 3;
              break;
            case ClassWriter.ITFMETH_INSN:
              v += 5;
              break;
            // case MANA_INSN:
            default:
              v += 4;
              break;
          }
        }
        // parses the try catch entries
        j = readUnsignedShort(v); v += 2;
        for ( ; j > 0; --j) {
          label = readUnsignedShort(v);
          if (labels[label] == null) {
            labels[label] = new Label();
          }
          label = readUnsignedShort(v + 2);
          if (labels[label] == null) {
            labels[label] = new Label();
          }
          label = readUnsignedShort(v + 4);
          if (labels[label] == null) {
            labels[label] = new Label();
          }
          v += 8;
        }
        // parses the local variable, line number tables, and code attributes
        j = readUnsignedShort(v); v += 2;
        for ( ; j > 0; --j) {
          String attrName = readUTF8(v, c);
          if (attrName.equals("LocalVariableTable")) {
            if (!skipDebug) {
              k = readUnsignedShort(v + 6);
              w = v + 8;
              for ( ; k > 0; --k) {
                label = readUnsignedShort(w);
                if (labels[label] == null) {
                  labels[label] = new Label();
                }
                label += readUnsignedShort(w + 2);
                if (labels[label] == null) {
                  labels[label] = new Label();
                }
                w += 10;
              }
            }
          } else if (attrName.equals("LineNumberTable")) {
            if (!skipDebug) {
              k = readUnsignedShort(v + 6);
              w = v + 8;
              for ( ; k > 0; --k) {
                label = readUnsignedShort(w);
                if (labels[label] == null) {
                  labels[label] = new Label();
                }
                labels[label].line = readUnsignedShort(w + 2);
                w += 4;
              }
            }
          } else {
            for (k = 0; k < attrs.length; ++k) {
              if (attrs[k].type.equals(attrName)) {
                attr = attrs[k].read(
                  this, v + 6, readInt(v + 2), c, codeStart - 8, labels);
                if (attr != null) {
                  attr.next = cattrs;
                  cattrs = attr;
                }
              }
            }
          }
          v += 6 + readInt(v + 2);
        }

        // 2nd phase: visits each instruction
        v = codeStart;
        Label l;
        while (v < codeEnd) {
          w = v - codeStart;
          l = labels[w];
          if (l != null) {
            cv.visitLabel(l);
            if (!skipDebug && l.line > 0) {
              cv.visitLineNumber(l.line, l);
            }
          }
          int opcode = b[v] & 0xFF;
          switch (ClassWriter.TYPE[opcode]) {
            case ClassWriter.NOARG_INSN:
              cv.visitInsn(opcode);
              v += 1;
              break;
            case ClassWriter.IMPLVAR_INSN:
              if (opcode > Constants.ISTORE) {
                opcode -= 59; //ISTORE_0
                cv.visitVarInsn(Constants.ISTORE + (opcode >> 2), opcode & 0x3);
              } else {
                opcode -= 26; //ILOAD_0
                cv.visitVarInsn(Constants.ILOAD + (opcode >> 2), opcode & 0x3);
              }
              v += 1;
              break;
            case ClassWriter.LABEL_INSN:
              cv.visitJumpInsn(opcode, labels[w + readShort(v + 1)]);
              v += 3;
              break;
            case ClassWriter.LABELW_INSN:
              cv.visitJumpInsn(opcode, labels[w + readInt(v + 1)]);
              v += 5;
              break;
            case ClassWriter.WIDE_INSN:
              opcode = b[v + 1] & 0xFF;
              if (opcode == Constants.IINC) {
                cv.visitIincInsn(readUnsignedShort(v + 2), readShort(v + 4));
                v += 6;
              } else {
                cv.visitVarInsn(opcode, readUnsignedShort(v + 2));
                v += 4;
              }
              break;
            case ClassWriter.TABL_INSN:
              // skips 0 to 3 padding bytes
              v = v + 4 - (w & 3);
              // reads instruction
              label = w + readInt(v); v += 4;
              int min = readInt(v); v += 4;
              int max = readInt(v); v += 4;
              Label[] table = new Label[max - min + 1];
              for (j = 0; j < table.length; ++j) {
                table[j] = labels[w + readInt(v)];
                v += 4;
              }
              cv.visitTableSwitchInsn(min, max, labels[label], table);
              break;
            case ClassWriter.LOOK_INSN:
              // skips 0 to 3 padding bytes
              v = v + 4 - (w & 3);
              // reads instruction
              label = w + readInt(v); v += 4;
              j = readInt(v); v += 4;
              int[] keys = new int[j];
              Label[] values = new Label[j];
              for (j = 0; j < keys.length; ++j) {
                keys[j] = readInt(v); v += 4;
                values[j] = labels[w + readInt(v)]; v += 4;
              }
              cv.visitLookupSwitchInsn(labels[label], keys, values);
              break;
            case ClassWriter.VAR_INSN:
              cv.visitVarInsn(opcode, b[v + 1] & 0xFF);
              v += 2;
              break;
            case ClassWriter.SBYTE_INSN:
              cv.visitIntInsn(opcode, b[v + 1]);
              v += 2;
              break;
            case ClassWriter.SHORT_INSN:
              cv.visitIntInsn(opcode, readShort(v + 1));
              v += 3;
              break;
            case ClassWriter.LDC_INSN:
              cv.visitLdcInsn(readConst(b[v + 1] & 0xFF, c));
              v += 2;
              break;
            case ClassWriter.LDCW_INSN:
              cv.visitLdcInsn(readConst(readUnsignedShort(v + 1), c));
              v += 3;
              break;
            case ClassWriter.FIELDORMETH_INSN:
            case ClassWriter.ITFMETH_INSN:
              int cpIndex = items[readUnsignedShort(v + 1)];
              String iowner = readClass(cpIndex, c);
              cpIndex = items[readUnsignedShort(cpIndex + 2)];
              String iname = readUTF8(cpIndex, c);
              String idesc = readUTF8(cpIndex + 2, c);
              if (opcode < Constants.INVOKEVIRTUAL) {
                cv.visitFieldInsn(opcode, iowner, iname, idesc);
              } else {
                cv.visitMethodInsn(opcode, iowner, iname, idesc);
              }
              if (opcode == Constants.INVOKEINTERFACE) {
                v += 5;
              } else {
                v += 3;