JVM 解释执行

2020-04-25  本文已影响0人  asdf____

JVM 字节码解释执行:
hotspot/src/share/vm/interpreter/bytecodeInterpreter.cpp
bytecodeInterpreter.cpp

run:

  DO_UPDATE_INSTRUCTION_COUNT(*pc)
  DEBUGGER_SINGLE_STEP_NOTIFY();
#ifdef PREFETCH_OPCCODE
  opcode = *pc;  /* prefetch first opcode */
#endif

#ifndef USELABELS
  while (1)
#endif
  {
#ifndef PREFETCH_OPCCODE
      opcode = *pc;
#endif
      // Seems like this happens twice per opcode. At worst this is only
      // need at entry to the loop.
      // DEBUGGER_SINGLE_STEP_NOTIFY();
      /* Using this labels avoids double breakpoints when quickening and
       * when returing from transition frames.
       */
  opcode_switch:
      assert(istate == orig, "Corrupted istate");
      /* QQQ Hmm this has knowledge of direction, ought to be a stack method */
      assert(topOfStack >= istate->stack_limit(), "Stack overrun");
      assert(topOfStack < istate->stack_base(), "Stack underrun");

#ifdef USELABELS
      DISPATCH(opcode);
#else
      switch (opcode)
#endif
      {
      CASE(_nop):
          UPDATE_PC_AND_CONTINUE(1);

          /* Push miscellaneous constants onto the stack. */

      CASE(_aconst_null):
          SET_STACK_OBJECT(NULL, 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);

#undef  OPC_CONST_n
#define OPC_CONST_n(opcode, const_type, value)                          \
      CASE(opcode):                                                     \
          SET_STACK_ ## const_type(value, 0);                           \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);

          OPC_CONST_n(_iconst_m1,   INT,       -1);
          OPC_CONST_n(_iconst_0,    INT,        0);
          OPC_CONST_n(_iconst_1,    INT,        1);
          OPC_CONST_n(_iconst_2,    INT,        2);
          OPC_CONST_n(_iconst_3,    INT,        3);
          OPC_CONST_n(_iconst_4,    INT,        4);
          OPC_CONST_n(_iconst_5,    INT,        5);
          OPC_CONST_n(_fconst_0,    FLOAT,      0.0);
          OPC_CONST_n(_fconst_1,    FLOAT,      1.0);
          OPC_CONST_n(_fconst_2,    FLOAT,      2.0);

#undef  OPC_CONST2_n
#define OPC_CONST2_n(opcname, value, key, kind)                         \
      CASE(_##opcname):                                                 \
      {                                                                 \
          SET_STACK_ ## kind(VM##key##Const##value(), 1);               \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);                         \
      }
         OPC_CONST2_n(dconst_0, Zero, double, DOUBLE);
         OPC_CONST2_n(dconst_1, One,  double, DOUBLE);
         OPC_CONST2_n(lconst_0, Zero, long, LONG);
         OPC_CONST2_n(lconst_1, One,  long, LONG);

         /* Load constant from constant pool: */

          /* Push a 1-byte signed integer value onto the stack. */
      CASE(_bipush):
          SET_STACK_INT((jbyte)(pc[1]), 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, 1);

          /* Push a 2-byte signed integer constant onto the stack. */
      CASE(_sipush):
          SET_STACK_INT((int16_t)Bytes::get_Java_u2(pc + 1), 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(3, 1);

          /* load from local variable */

      CASE(_aload):
          VERIFY_OOP(LOCALS_OBJECT(pc[1]));
          SET_STACK_OBJECT(LOCALS_OBJECT(pc[1]), 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, 1);

      CASE(_iload):
      CASE(_fload):
          SET_STACK_SLOT(LOCALS_SLOT(pc[1]), 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, 1);

      CASE(_lload):
          SET_STACK_LONG_FROM_ADDR(LOCALS_LONG_AT(pc[1]), 1);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, 2);

      CASE(_dload):
          SET_STACK_DOUBLE_FROM_ADDR(LOCALS_DOUBLE_AT(pc[1]), 1);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, 2);

#undef  OPC_LOAD_n
#define OPC_LOAD_n(num)                                                 \
      CASE(_aload_##num):                                               \
          VERIFY_OOP(LOCALS_OBJECT(num));                               \
          SET_STACK_OBJECT(LOCALS_OBJECT(num), 0);                      \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);                         \
                                                                        \
      CASE(_iload_##num):                                               \
      CASE(_fload_##num):                                               \
          SET_STACK_SLOT(LOCALS_SLOT(num), 0);                          \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);                         \
                                                                        \
      CASE(_lload_##num):                                               \
          SET_STACK_LONG_FROM_ADDR(LOCALS_LONG_AT(num), 1);             \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);                         \
      CASE(_dload_##num):                                               \
          SET_STACK_DOUBLE_FROM_ADDR(LOCALS_DOUBLE_AT(num), 1);         \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);

          OPC_LOAD_n(0);
          OPC_LOAD_n(1);
          OPC_LOAD_n(2);
          OPC_LOAD_n(3);

          /* store to a local variable */

      CASE(_astore):
          astore(topOfStack, -1, locals, pc[1]);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, -1);

      CASE(_istore):
      CASE(_fstore):
          SET_LOCALS_SLOT(STACK_SLOT(-1), pc[1]);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, -1);

      CASE(_lstore):
          SET_LOCALS_LONG(STACK_LONG(-1), pc[1]);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, -2);

      CASE(_dstore):
          SET_LOCALS_DOUBLE(STACK_DOUBLE(-1), pc[1]);
          UPDATE_PC_AND_TOS_AND_CONTINUE(2, -2);

      CASE(_wide): {
          uint16_t reg = Bytes::get_Java_u2(pc + 2);

          opcode = pc[1];
          switch(opcode) {
              case Bytecodes::_aload:
                  VERIFY_OOP(LOCALS_OBJECT(reg));
                  SET_STACK_OBJECT(LOCALS_OBJECT(reg), 0);
                  UPDATE_PC_AND_TOS_AND_CONTINUE(4, 1);

              case Bytecodes::_iload:
              case Bytecodes::_fload:
                  SET_STACK_SLOT(LOCALS_SLOT(reg), 0);
                  UPDATE_PC_AND_TOS_AND_CONTINUE(4, 1);

              case Bytecodes::_lload:
                  SET_STACK_LONG_FROM_ADDR(LOCALS_LONG_AT(reg), 1);
                  UPDATE_PC_AND_TOS_AND_CONTINUE(4, 2);

              case Bytecodes::_dload:
                  SET_STACK_DOUBLE_FROM_ADDR(LOCALS_LONG_AT(reg), 1);
                  UPDATE_PC_AND_TOS_AND_CONTINUE(4, 2);

              case Bytecodes::_astore:
                  astore(topOfStack, -1, locals, reg);
                  UPDATE_PC_AND_TOS_AND_CONTINUE(4, -1);

              case Bytecodes::_istore:
              case Bytecodes::_fstore:
                  SET_LOCALS_SLOT(STACK_SLOT(-1), reg);
                  UPDATE_PC_AND_TOS_AND_CONTINUE(4, -1);

              case Bytecodes::_lstore:
                  SET_LOCALS_LONG(STACK_LONG(-1), reg);
                  UPDATE_PC_AND_TOS_AND_CONTINUE(4, -2);

              case Bytecodes::_dstore:
                  SET_LOCALS_DOUBLE(STACK_DOUBLE(-1), reg);
                  UPDATE_PC_AND_TOS_AND_CONTINUE(4, -2);

              case Bytecodes::_iinc: {
                  int16_t offset = (int16_t)Bytes::get_Java_u2(pc+4);
                  // Be nice to see what this generates.... QQQ
                  SET_LOCALS_INT(LOCALS_INT(reg) + offset, reg);
                  UPDATE_PC_AND_CONTINUE(6);
              }
              case Bytecodes::_ret:
                  pc = istate->method()->code_base() + (intptr_t)(LOCALS_ADDR(reg));
                  UPDATE_PC_AND_CONTINUE(0);
              default:
                  VM_JAVA_ERROR(vmSymbols::java_lang_InternalError(), "undefined opcode");
          }
      }


#undef  OPC_STORE_n
#define OPC_STORE_n(num)                                                \
      CASE(_astore_##num):                                              \
          astore(topOfStack, -1, locals, num);                          \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);                        \
      CASE(_istore_##num):                                              \
      CASE(_fstore_##num):                                              \
          SET_LOCALS_SLOT(STACK_SLOT(-1), num);                         \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);

          OPC_STORE_n(0);
          OPC_STORE_n(1);
          OPC_STORE_n(2);
          OPC_STORE_n(3);

#undef  OPC_DSTORE_n
#define OPC_DSTORE_n(num)                                               \
      CASE(_dstore_##num):                                              \
          SET_LOCALS_DOUBLE(STACK_DOUBLE(-1), num);                     \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -2);                        \
      CASE(_lstore_##num):                                              \
          SET_LOCALS_LONG(STACK_LONG(-1), num);                         \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -2);

          OPC_DSTORE_n(0);
          OPC_DSTORE_n(1);
          OPC_DSTORE_n(2);
          OPC_DSTORE_n(3);

          /* stack pop, dup, and insert opcodes */


      CASE(_pop):                /* Discard the top item on the stack */
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);


      CASE(_pop2):               /* Discard the top 2 items on the stack */
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -2);


      CASE(_dup):               /* Duplicate the top item on the stack */
          dup(topOfStack);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);

      CASE(_dup2):              /* Duplicate the top 2 items on the stack */
          dup2(topOfStack);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);

      CASE(_dup_x1):    /* insert top word two down */
          dup_x1(topOfStack);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);

      CASE(_dup_x2):    /* insert top word three down  */
          dup_x2(topOfStack);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);

      CASE(_dup2_x1):   /* insert top 2 slots three down */
          dup2_x1(topOfStack);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);

      CASE(_dup2_x2):   /* insert top 2 slots four down */
          dup2_x2(topOfStack);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);

      CASE(_swap): {        /* swap top two elements on the stack */
          swap(topOfStack);
          UPDATE_PC_AND_CONTINUE(1);
      }

          /* Perform various binary integer operations */

#undef  OPC_INT_BINARY
#define OPC_INT_BINARY(opcname, opname, test)                           \
      CASE(_i##opcname):                                                \
          if (test && (STACK_INT(-1) == 0)) {                           \
              VM_JAVA_ERROR(vmSymbols::java_lang_ArithmeticException(), \
                            "/ by zero");                               \
          }                                                             \
          SET_STACK_INT(VMint##opname(STACK_INT(-2),                    \
                                      STACK_INT(-1)),                   \
                                      -2);                              \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);                        \
      CASE(_l##opcname):                                                \
      {                                                                 \
          if (test) {                                                   \
            jlong l1 = STACK_LONG(-1);                                  \
            if (VMlongEqz(l1)) {                                        \
              VM_JAVA_ERROR(vmSymbols::java_lang_ArithmeticException(), \
                            "/ by long zero");                          \
            }                                                           \
          }                                                             \
          /* First long at (-1,-2) next long at (-3,-4) */              \
          SET_STACK_LONG(VMlong##opname(STACK_LONG(-3),                 \
                                        STACK_LONG(-1)),                \
                                        -3);                            \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -2);                        \
      }

      OPC_INT_BINARY(add, Add, 0);
      OPC_INT_BINARY(sub, Sub, 0);
      OPC_INT_BINARY(mul, Mul, 0);
      OPC_INT_BINARY(and, And, 0);
      OPC_INT_BINARY(or,  Or,  0);
      OPC_INT_BINARY(xor, Xor, 0);
      OPC_INT_BINARY(div, Div, 1);
      OPC_INT_BINARY(rem, Rem, 1);


      /* Perform various binary floating number operations */
      /* On some machine/platforms/compilers div zero check can be implicit */

#undef  OPC_FLOAT_BINARY
#define OPC_FLOAT_BINARY(opcname, opname)                                  \
      CASE(_d##opcname): {                                                 \
          SET_STACK_DOUBLE(VMdouble##opname(STACK_DOUBLE(-3),              \
                                            STACK_DOUBLE(-1)),             \
                                            -3);                           \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -2);                           \
      }                                                                    \
      CASE(_f##opcname):                                                   \
          SET_STACK_FLOAT(VMfloat##opname(STACK_FLOAT(-2),                 \
                                          STACK_FLOAT(-1)),                \
                                          -2);                             \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);


     OPC_FLOAT_BINARY(add, Add);
     OPC_FLOAT_BINARY(sub, Sub);
     OPC_FLOAT_BINARY(mul, Mul);
     OPC_FLOAT_BINARY(div, Div);
     OPC_FLOAT_BINARY(rem, Rem);

      /* Shift operations
       * Shift left int and long: ishl, lshl
       * Logical shift right int and long w/zero extension: iushr, lushr
       * Arithmetic shift right int and long w/sign extension: ishr, lshr
       */

#undef  OPC_SHIFT_BINARY
#define OPC_SHIFT_BINARY(opcname, opname)                               \
      CASE(_i##opcname):                                                \
         SET_STACK_INT(VMint##opname(STACK_INT(-2),                     \
                                     STACK_INT(-1)),                    \
                                     -2);                               \
         UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);                         \
      CASE(_l##opcname):                                                \
      {                                                                 \
         SET_STACK_LONG(VMlong##opname(STACK_LONG(-2),                  \
                                       STACK_INT(-1)),                  \
                                       -2);                             \
         UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);                         \
      }

      OPC_SHIFT_BINARY(shl, Shl);
      OPC_SHIFT_BINARY(shr, Shr);
      OPC_SHIFT_BINARY(ushr, Ushr);

     /* Increment local variable by constant */
      CASE(_iinc):
      {
          // locals[pc[1]].j.i += (jbyte)(pc[2]);
          SET_LOCALS_INT(LOCALS_INT(pc[1]) + (jbyte)(pc[2]), pc[1]);
          UPDATE_PC_AND_CONTINUE(3);
      }

     /* negate the value on the top of the stack */

      CASE(_ineg):
         SET_STACK_INT(VMintNeg(STACK_INT(-1)), -1);
         UPDATE_PC_AND_CONTINUE(1);

      CASE(_fneg):
         SET_STACK_FLOAT(VMfloatNeg(STACK_FLOAT(-1)), -1);
         UPDATE_PC_AND_CONTINUE(1);

      CASE(_lneg):
      {
         SET_STACK_LONG(VMlongNeg(STACK_LONG(-1)), -1);
         UPDATE_PC_AND_CONTINUE(1);
      }

      CASE(_dneg):
      {
         SET_STACK_DOUBLE(VMdoubleNeg(STACK_DOUBLE(-1)), -1);
         UPDATE_PC_AND_CONTINUE(1);
      }

      /* Conversion operations */

      CASE(_i2f):       /* convert top of stack int to float */
         SET_STACK_FLOAT(VMint2Float(STACK_INT(-1)), -1);
         UPDATE_PC_AND_CONTINUE(1);

      CASE(_i2l):       /* convert top of stack int to long */
      {
          // this is ugly QQQ
          jlong r = VMint2Long(STACK_INT(-1));
          MORE_STACK(-1); // Pop
          SET_STACK_LONG(r, 1);

          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);
      }

      CASE(_i2d):       /* convert top of stack int to double */
      {
          // this is ugly QQQ (why cast to jlong?? )
          jdouble r = (jlong)STACK_INT(-1);
          MORE_STACK(-1); // Pop
          SET_STACK_DOUBLE(r, 1);

          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);
      }

      CASE(_l2i):       /* convert top of stack long to int */
      {
          jint r = VMlong2Int(STACK_LONG(-1));
          MORE_STACK(-2); // Pop
          SET_STACK_INT(r, 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);
      }

      CASE(_l2f):   /* convert top of stack long to float */
      {
          jlong r = STACK_LONG(-1);
          MORE_STACK(-2); // Pop
          SET_STACK_FLOAT(VMlong2Float(r), 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);
      }

      CASE(_l2d):       /* convert top of stack long to double */
      {
          jlong r = STACK_LONG(-1);
          MORE_STACK(-2); // Pop
          SET_STACK_DOUBLE(VMlong2Double(r), 1);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);
      }

      CASE(_f2i):  /* Convert top of stack float to int */
          SET_STACK_INT(SharedRuntime::f2i(STACK_FLOAT(-1)), -1);
          UPDATE_PC_AND_CONTINUE(1);

      CASE(_f2l):  /* convert top of stack float to long */
      {
          jlong r = SharedRuntime::f2l(STACK_FLOAT(-1));
          MORE_STACK(-1); // POP
          SET_STACK_LONG(r, 1);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);
      }

      CASE(_f2d):  /* convert top of stack float to double */
      {
          jfloat f;
          jdouble r;
          f = STACK_FLOAT(-1);
          r = (jdouble) f;
          MORE_STACK(-1); // POP
          SET_STACK_DOUBLE(r, 1);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);
      }

      CASE(_d2i): /* convert top of stack double to int */
      {
          jint r1 = SharedRuntime::d2i(STACK_DOUBLE(-1));
          MORE_STACK(-2);
          SET_STACK_INT(r1, 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);
      }

      CASE(_d2f): /* convert top of stack double to float */
      {
          jfloat r1 = VMdouble2Float(STACK_DOUBLE(-1));
          MORE_STACK(-2);
          SET_STACK_FLOAT(r1, 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);
      }

      CASE(_d2l): /* convert top of stack double to long */
      {
          jlong r1 = SharedRuntime::d2l(STACK_DOUBLE(-1));
          MORE_STACK(-2);
          SET_STACK_LONG(r1, 1);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 2);
      }

      CASE(_i2b):
          SET_STACK_INT(VMint2Byte(STACK_INT(-1)), -1);
          UPDATE_PC_AND_CONTINUE(1);

      CASE(_i2c):
          SET_STACK_INT(VMint2Char(STACK_INT(-1)), -1);
          UPDATE_PC_AND_CONTINUE(1);

      CASE(_i2s):
          SET_STACK_INT(VMint2Short(STACK_INT(-1)), -1);
          UPDATE_PC_AND_CONTINUE(1);

      /* comparison operators */


#define COMPARISON_OP(name, comparison)                                      \
      CASE(_if_icmp##name): {                                                \
          int skip = (STACK_INT(-2) comparison STACK_INT(-1))                \
                      ? (int16_t)Bytes::get_Java_u2(pc + 1) : 3;             \
          address branch_pc = pc;                                            \
          UPDATE_PC_AND_TOS(skip, -2);                                       \
          DO_BACKEDGE_CHECKS(skip, branch_pc);                               \
          CONTINUE;                                                          \
      }                                                                      \
      CASE(_if##name): {                                                     \
          int skip = (STACK_INT(-1) comparison 0)                            \
                      ? (int16_t)Bytes::get_Java_u2(pc + 1) : 3;             \
          address branch_pc = pc;                                            \
          UPDATE_PC_AND_TOS(skip, -1);                                       \
          DO_BACKEDGE_CHECKS(skip, branch_pc);                               \
          CONTINUE;                                                          \
      }

#define COMPARISON_OP2(name, comparison)                                     \
      COMPARISON_OP(name, comparison)                                        \
      CASE(_if_acmp##name): {                                                \
          int skip = (STACK_OBJECT(-2) comparison STACK_OBJECT(-1))          \
                       ? (int16_t)Bytes::get_Java_u2(pc + 1) : 3;            \
          address branch_pc = pc;                                            \
          UPDATE_PC_AND_TOS(skip, -2);                                       \
          DO_BACKEDGE_CHECKS(skip, branch_pc);                               \
          CONTINUE;                                                          \
      }

#define NULL_COMPARISON_NOT_OP(name)                                         \
      CASE(_if##name): {                                                     \
          int skip = (!(STACK_OBJECT(-1) == NULL))                           \
                      ? (int16_t)Bytes::get_Java_u2(pc + 1) : 3;             \
          address branch_pc = pc;                                            \
          UPDATE_PC_AND_TOS(skip, -1);                                       \
          DO_BACKEDGE_CHECKS(skip, branch_pc);                               \
          CONTINUE;                                                          \
      }

#define NULL_COMPARISON_OP(name)                                             \
      CASE(_if##name): {                                                     \
          int skip = ((STACK_OBJECT(-1) == NULL))                            \
                      ? (int16_t)Bytes::get_Java_u2(pc + 1) : 3;             \
          address branch_pc = pc;                                            \
          UPDATE_PC_AND_TOS(skip, -1);                                       \
          DO_BACKEDGE_CHECKS(skip, branch_pc);                               \
          CONTINUE;                                                          \
      }
      COMPARISON_OP(lt, <);
      COMPARISON_OP(gt, >);
      COMPARISON_OP(le, <=);
      COMPARISON_OP(ge, >=);
      COMPARISON_OP2(eq, ==);  /* include ref comparison */
      COMPARISON_OP2(ne, !=);  /* include ref comparison */
      NULL_COMPARISON_OP(null);
      NULL_COMPARISON_NOT_OP(nonnull);

      /* Goto pc at specified offset in switch table. */

      CASE(_tableswitch): {
          jint* lpc  = (jint*)VMalignWordUp(pc+1);
          int32_t  key  = STACK_INT(-1);
          int32_t  low  = Bytes::get_Java_u4((address)&lpc[1]);
          int32_t  high = Bytes::get_Java_u4((address)&lpc[2]);
          int32_t  skip;
          key -= low;
          skip = ((uint32_t) key > (uint32_t)(high - low))
                      ? Bytes::get_Java_u4((address)&lpc[0])
                      : Bytes::get_Java_u4((address)&lpc[key + 3]);
          // Does this really need a full backedge check (osr?)
          address branch_pc = pc;
          UPDATE_PC_AND_TOS(skip, -1);
          DO_BACKEDGE_CHECKS(skip, branch_pc);
          CONTINUE;
      }

      /* Goto pc whose table entry matches specified key */

      CASE(_lookupswitch): {
          jint* lpc  = (jint*)VMalignWordUp(pc+1);
          int32_t  key  = STACK_INT(-1);
          int32_t  skip = Bytes::get_Java_u4((address) lpc); /* default amount */
          int32_t  npairs = Bytes::get_Java_u4((address) &lpc[1]);
          while (--npairs >= 0) {
              lpc += 2;
              if (key == (int32_t)Bytes::get_Java_u4((address)lpc)) {
                  skip = Bytes::get_Java_u4((address)&lpc[1]);
                  break;
              }
          }
          address branch_pc = pc;
          UPDATE_PC_AND_TOS(skip, -1);
          DO_BACKEDGE_CHECKS(skip, branch_pc);
          CONTINUE;
      }

      CASE(_fcmpl):
      CASE(_fcmpg):
      {
          SET_STACK_INT(VMfloatCompare(STACK_FLOAT(-2),
                                        STACK_FLOAT(-1),
                                        (opcode == Bytecodes::_fcmpl ? -1 : 1)),
                        -2);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);
      }

      CASE(_dcmpl):
      CASE(_dcmpg):
      {
          int r = VMdoubleCompare(STACK_DOUBLE(-3),
                                  STACK_DOUBLE(-1),
                                  (opcode == Bytecodes::_dcmpl ? -1 : 1));
          MORE_STACK(-4); // Pop
          SET_STACK_INT(r, 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);
      }

      CASE(_lcmp):
      {
          int r = VMlongCompare(STACK_LONG(-3), STACK_LONG(-1));
          MORE_STACK(-4);
          SET_STACK_INT(r, 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, 1);
      }


      /* Return from a method */

      CASE(_areturn):
      CASE(_ireturn):
      CASE(_freturn):
      {
          // Allow a safepoint before returning to frame manager.
          SAFEPOINT;

          goto handle_return;
      }

      CASE(_lreturn):
      CASE(_dreturn):
      {
          // Allow a safepoint before returning to frame manager.
          SAFEPOINT;
          goto handle_return;
      }

      CASE(_return_register_finalizer): {

          oop rcvr = LOCALS_OBJECT(0);
          VERIFY_OOP(rcvr);
          if (rcvr->klass()->has_finalizer()) {
            CALL_VM(InterpreterRuntime::register_finalizer(THREAD, rcvr), handle_exception);
          }
          goto handle_return;
      }
      CASE(_return): {

          // Allow a safepoint before returning to frame manager.
          SAFEPOINT;
          goto handle_return;
      }

      /* Array access byte-codes */

      /* Every array access byte-code starts out like this */
//        arrayOopDesc* arrObj = (arrayOopDesc*)STACK_OBJECT(arrayOff);
#define ARRAY_INTRO(arrayOff)                                                  \
      arrayOop arrObj = (arrayOop)STACK_OBJECT(arrayOff);                      \
      jint     index  = STACK_INT(arrayOff + 1);                               \
      char message[jintAsStringSize];                                          \
      CHECK_NULL(arrObj);                                                      \
      if ((uint32_t)index >= (uint32_t)arrObj->length()) {                     \
          sprintf(message, "%d", index);                                       \
          VM_JAVA_ERROR(vmSymbols::java_lang_ArrayIndexOutOfBoundsException(), \
                        message);                                              \
      }

      /* 32-bit loads. These handle conversion from < 32-bit types */
#define ARRAY_LOADTO32(T, T2, format, stackRes, extra)                                \
      {                                                                               \
          ARRAY_INTRO(-2);                                                            \
          (void)extra;                                                                \
          SET_ ## stackRes(*(T2 *)(((address) arrObj->base(T)) + index * sizeof(T2)), \
                           -2);                                                       \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);                                      \
      }

      /* 64-bit loads */
#define ARRAY_LOADTO64(T,T2, stackRes, extra)                                              \
      {                                                                                    \
          ARRAY_INTRO(-2);                                                                 \
          SET_ ## stackRes(*(T2 *)(((address) arrObj->base(T)) + index * sizeof(T2)), -1); \
          (void)extra;                                                                     \
          UPDATE_PC_AND_CONTINUE(1);                                                       \
      }

      CASE(_iaload):
          ARRAY_LOADTO32(T_INT, jint,   "%d",   STACK_INT, 0);
      CASE(_faload):
          ARRAY_LOADTO32(T_FLOAT, jfloat, "%f",   STACK_FLOAT, 0);
      CASE(_aaload):
          ARRAY_LOADTO32(T_OBJECT, oop,   INTPTR_FORMAT, STACK_OBJECT, 0);
      CASE(_baload):
          ARRAY_LOADTO32(T_BYTE, jbyte,  "%d",   STACK_INT, 0);
      CASE(_caload):
          ARRAY_LOADTO32(T_CHAR,  jchar, "%d",   STACK_INT, 0);
      CASE(_saload):
          ARRAY_LOADTO32(T_SHORT, jshort, "%d",   STACK_INT, 0);
      CASE(_laload):
          ARRAY_LOADTO64(T_LONG, jlong, STACK_LONG, 0);
      CASE(_daload):
          ARRAY_LOADTO64(T_DOUBLE, jdouble, STACK_DOUBLE, 0);

      /* 32-bit stores. These handle conversion to < 32-bit types */
#define ARRAY_STOREFROM32(T, T2, format, stackSrc, extra)                            \
      {                                                                              \
          ARRAY_INTRO(-3);                                                           \
          (void)extra;                                                               \
          *(T2 *)(((address) arrObj->base(T)) + index * sizeof(T2)) = stackSrc( -1); \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -3);                                     \
      }

      /* 64-bit stores */
#define ARRAY_STOREFROM64(T, T2, stackSrc, extra)                                    \
      {                                                                              \
          ARRAY_INTRO(-4);                                                           \
          (void)extra;                                                               \
          *(T2 *)(((address) arrObj->base(T)) + index * sizeof(T2)) = stackSrc( -1); \
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -4);                                     \
      }

      CASE(_iastore):
          ARRAY_STOREFROM32(T_INT, jint,   "%d",   STACK_INT, 0);
      CASE(_fastore):
          ARRAY_STOREFROM32(T_FLOAT, jfloat, "%f",   STACK_FLOAT, 0);
      /*
       * This one looks different because of the assignability check
       */
      CASE(_aastore): {
          oop rhsObject = STACK_OBJECT(-1);
          VERIFY_OOP(rhsObject);
          ARRAY_INTRO( -3);
          // arrObj, index are set
          if (rhsObject != NULL) {
            /* Check assignability of rhsObject into arrObj */
            Klass* rhsKlassOop = rhsObject->klass(); // EBX (subclass)
            Klass* elemKlassOop = ObjArrayKlass::cast(arrObj->klass())->element_klass(); // superklass EAX
            //
            // Check for compatibilty. This check must not GC!!
            // Seems way more expensive now that we must dispatch
            //
            if (rhsKlassOop != elemKlassOop && !rhsKlassOop->is_subtype_of(elemKlassOop)) { // ebx->is...
              VM_JAVA_ERROR(vmSymbols::java_lang_ArrayStoreException(), "");
            }
          }
          oop* elem_loc = (oop*)(((address) arrObj->base(T_OBJECT)) + index * sizeof(oop));
          // *(oop*)(((address) arrObj->base(T_OBJECT)) + index * sizeof(oop)) = rhsObject;
          *elem_loc = rhsObject;
          // Mark the card
          OrderAccess::release_store(&BYTE_MAP_BASE[(uintptr_t)elem_loc >> CardTableModRefBS::card_shift], 0);
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -3);
      }
      CASE(_bastore):
          ARRAY_STOREFROM32(T_BYTE, jbyte,  "%d",   STACK_INT, 0);
      CASE(_castore):
          ARRAY_STOREFROM32(T_CHAR, jchar,  "%d",   STACK_INT, 0);
      CASE(_sastore):
          ARRAY_STOREFROM32(T_SHORT, jshort, "%d",   STACK_INT, 0);
      CASE(_lastore):
          ARRAY_STOREFROM64(T_LONG, jlong, STACK_LONG, 0);
      CASE(_dastore):
          ARRAY_STOREFROM64(T_DOUBLE, jdouble, STACK_DOUBLE, 0);

      CASE(_arraylength):
      {
          arrayOop ary = (arrayOop) STACK_OBJECT(-1);
          CHECK_NULL(ary);
          SET_STACK_INT(ary->length(), -1);
          UPDATE_PC_AND_CONTINUE(1);
      }

      /* monitorenter and monitorexit for locking/unlocking an object */

      CASE(_monitorenter): {
        oop lockee = STACK_OBJECT(-1);
        // derefing's lockee ought to provoke implicit null check
        CHECK_NULL(lockee);
        // find a free monitor or one already allocated for this object
        // if we find a matching object then we need a new monitor
        // since this is recursive enter
        BasicObjectLock* limit = istate->monitor_base();
        BasicObjectLock* most_recent = (BasicObjectLock*) istate->stack_base();
        BasicObjectLock* entry = NULL;
        while (most_recent != limit ) {
          if (most_recent->obj() == NULL) entry = most_recent;
          else if (most_recent->obj() == lockee) break;
          most_recent++;
        }
        if (entry != NULL) {
          entry->set_obj(lockee);
          markOop displaced = lockee->mark()->set_unlocked();
          entry->lock()->set_displaced_header(displaced);
          if (Atomic::cmpxchg_ptr(entry, lockee->mark_addr(), displaced) != displaced) {
            // Is it simple recursive case?
            if (THREAD->is_lock_owned((address) displaced->clear_lock_bits())) {
              entry->lock()->set_displaced_header(NULL);
            } else {
              CALL_VM(InterpreterRuntime::monitorenter(THREAD, entry), handle_exception);
            }
          }
          UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);
        } else {
          istate->set_msg(more_monitors);
          UPDATE_PC_AND_RETURN(0); // Re-execute
        }
      }

      CASE(_monitorexit): {
        oop lockee = STACK_OBJECT(-1);
        CHECK_NULL(lockee);
        // derefing's lockee ought to provoke implicit null check
        // find our monitor slot
        BasicObjectLock* limit = istate->monitor_base();
        BasicObjectLock* most_recent = (BasicObjectLock*) istate->stack_base();
        while (most_recent != limit ) {
          if ((most_recent)->obj() == lockee) {
            BasicLock* lock = most_recent->lock();
            markOop header = lock->displaced_header();
            most_recent->set_obj(NULL);
            // If it isn't recursive we either must swap old header or call the runtime
            if (header != NULL) {
              if (Atomic::cmpxchg_ptr(header, lockee->mark_addr(), lock) != lock) {
                // restore object for the slow case
                most_recent->set_obj(lockee);
                CALL_VM(InterpreterRuntime::monitorexit(THREAD, most_recent), handle_exception);
              }
            }
            UPDATE_PC_AND_TOS_AND_CONTINUE(1, -1);
          }
          most_recent++;
        }
        // Need to throw illegal monitor state exception
        CALL_VM(InterpreterRuntime::throw_illegal_monitor_state_exception(THREAD), handle_exception);
        ShouldNotReachHere();
      }

      /* All of the non-quick opcodes. */

      /* -Set clobbersCpIndex true if the quickened opcode clobbers the
       *  constant pool index in the instruction.
       */
      CASE(_getfield):
      CASE(_getstatic):
        {
          u2 index;
          ConstantPoolCacheEntry* cache;
          index = Bytes::get_native_u2(pc+1);

          // QQQ Need to make this as inlined as possible. Probably need to
          // split all the bytecode cases out so c++ compiler has a chance
          // for constant prop to fold everything possible away.

          cache = cp->entry_at(index);
          if (!cache->is_resolved((Bytecodes::Code)opcode)) {
            CALL_VM(InterpreterRuntime::resolve_get_put(THREAD, (Bytecodes::Code)opcode),
                    handle_exception);
            cache = cp->entry_at(index);
          }

#ifdef VM_JVMTI
          if (_jvmti_interp_events) {
            int *count_addr;
            oop obj;
            // Check to see if a field modification watch has been set
            // before we take the time to call into the VM.
            count_addr = (int *)JvmtiExport::get_field_access_count_addr();
            if ( *count_addr > 0 ) {
              if ((Bytecodes::Code)opcode == Bytecodes::_getstatic) {
                obj = (oop)NULL;
              } else {
                obj = (oop) STACK_OBJECT(-1);
                VERIFY_OOP(obj);
              }
              CALL_VM(InterpreterRuntime::post_field_access(THREAD,
                                          obj,
                                          cache),
                                          handle_exception);
            }
          }
#endif /* VM_JVMTI */

          oop obj;
          if ((Bytecodes::Code)opcode == Bytecodes::_getstatic) {
            Klass* k = cache->f1_as_klass();
            obj = k->java_mirror();
            MORE_STACK(1);  // Assume single slot push
          } else {
            obj = (oop) STACK_OBJECT(-1);
            CHECK_NULL(obj);
          }

          //
          // Now store the result on the stack
          //
          TosState tos_type = cache->flag_state();
          int field_offset = cache->f2_as_index();
          if (cache->is_volatile()) {
            if (tos_type == atos) {
              VERIFY_OOP(obj->obj_field_acquire(field_offset));
              SET_STACK_OBJECT(obj->obj_field_acquire(field_offset), -1);
            } else if (tos_type == itos) {
              SET_STACK_INT(obj->int_field_acquire(field_offset), -1);
            } else if (tos_type == ltos) {
              SET_STACK_LONG(obj->long_field_acquire(field_offset), 0);
              MORE_STACK(1);
            } else if (tos_type == btos) {
              SET_STACK_INT(obj->byte_field_acquire(field_offset), -1);
            } else if (tos_type == ctos) {
              SET_STACK_INT(obj->char_field_acquire(field_offset), -1);
            } else if (tos_type == stos) {
              SET_STACK_INT(obj->short_field_acquire(field_offset), -1);
            } else if (tos_type == ftos) {
              SET_STACK_FLOAT(obj->float_field_acquire(field_offset), -1);
            } else {
              SET_STACK_DOUBLE(obj->double_field_acquire(field_offset), 0);
              MORE_STACK(1);
            }
          } else {
            if (tos_type == atos) {
              VERIFY_OOP(obj->obj_field(field_offset));
              SET_STACK_OBJECT(obj->obj_field(field_offset), -1);
            } else if (tos_type == itos) {
              SET_STACK_INT(obj->int_field(field_offset), -1);
            } else if (tos_type == ltos) {
              SET_STACK_LONG(obj->long_field(field_offset), 0);
              MORE_STACK(1);
            } else if (tos_type == btos) {
              SET_STACK_INT(obj->byte_field(field_offset), -1);
            } else if (tos_type == ctos) {
              SET_STACK_INT(obj->char_field(field_offset), -1);
            } else if (tos_type == stos) {
              SET_STACK_INT(obj->short_field(field_offset), -1);
            } else if (tos_type == ftos) {
              SET_STACK_FLOAT(obj->float_field(field_offset), -1);
            } else {
              SET_STACK_DOUBLE(obj->double_field(field_offset), 0);
              MORE_STACK(1);
            }
          }

          UPDATE_PC_AND_CONTINUE(3);
         }

      CASE(_putfield):
      CASE(_putstatic):
        {
          u2 index = Bytes::get_native_u2(pc+1);
          ConstantPoolCacheEntry* cache = cp->entry_at(index);
          if (!cache->is_resolved((Bytecodes::Code)opcode)) {
            CALL_VM(InterpreterRuntime::resolve_get_put(THREAD, (Bytecodes::Code)opcode),
                    handle_exception);
            cache = cp->entry_at(index);
          }

#ifdef VM_JVMTI
          if (_jvmti_interp_events) {
            int *count_addr;
            oop obj;
            // Check to see if a field modification watch has been set
            // before we take the time to call into the VM.
            count_addr = (int *)JvmtiExport::get_field_modification_count_addr();
            if ( *count_addr > 0 ) {
              if ((Bytecodes::Code)opcode == Bytecodes::_putstatic) {
                obj = (oop)NULL;
              }
              else {
                if (cache->is_long() || cache->is_double()) {
                  obj = (oop) STACK_OBJECT(-3);
                } else {
                  obj = (oop) STACK_OBJECT(-2);
                }
                VERIFY_OOP(obj);
              }

              CALL_VM(InterpreterRuntime::post_field_modification(THREAD,
                                          obj,
                                          cache,
                                          (jvalue *)STACK_SLOT(-1)),
                                          handle_exception);
            }
          }
#endif /* VM_JVMTI */

          // QQQ Need to make this as inlined as possible. Probably need to split all the bytecode cases
          // out so c++ compiler has a chance for constant prop to fold everything possible away.

          oop obj;
          int count;
          TosState tos_type = cache->flag_state();

          count = -1;
          if (tos_type == ltos || tos_type == dtos) {
            --count;
          }
          if ((Bytecodes::Code)opcode == Bytecodes::_putstatic) {
            Klass* k = cache->f1_as_klass();
            obj = k->java_mirror();
          } else {
            --count;
            obj = (oop) STACK_OBJECT(count);
            CHECK_NULL(obj);
          }

          //
          // Now store the result
          //
          int field_offset = cache->f2_as_index();
          if (cache->is_volatile()) {
            if (tos_type == itos) {
              obj->release_int_field_put(field_offset, STACK_INT(-1));
            } else if (tos_type == atos) {
              VERIFY_OOP(STACK_OBJECT(-1));
              obj->release_obj_field_put(field_offset, STACK_OBJECT(-1));
              OrderAccess::release_store(&BYTE_MAP_BASE[(uintptr_t)obj >> CardTableModRefBS::card_shift], 0);
            } else if (tos_type == btos) {
              obj->release_byte_field_put(field_offset, STACK_INT(-1));
            } else if (tos_type == ltos) {
              obj->release_long_field_put(field_offset, STACK_LONG(-1));
            } else if (tos_type == ctos) {
              obj->release_char_field_put(field_offset, STACK_INT(-1));
            } else if (tos_type == stos) {
              obj->release_short_field_put(field_offset, STACK_INT(-1));
            } else if (tos_type == ftos) {
              obj->release_float_field_put(field_offset, STACK_FLOAT(-1));
            } else {
              obj->release_double_field_put(field_offset, STACK_DOUBLE(-1));
            }
            OrderAccess::storeload();
          } else {
            if (tos_type == itos) {
              obj->int_field_put(field_offset, STACK_INT(-1));
            } else if (tos_type == atos) {
              VERIFY_OOP(STACK_OBJECT(-1));
              obj->obj_field_put(field_offset, STACK_OBJECT(-1));
              OrderAccess::release_store(&BYTE_MAP_BASE[(uintptr_t)obj >> CardTableModRefBS::card_shift], 0);
            } else if (tos_type == btos) {
              obj->byte_field_put(field_offset, STACK_INT(-1));
            } else if (tos_type == ltos) {
              obj->long_field_put(field_offset, STACK_LONG(-1));
            } else if (tos_type == ctos) {
              obj->char_field_put(field_offset, STACK_INT(-1));
            } else if (tos_type == stos) {
              obj->short_field_put(field_offset, STACK_INT(-1));
            } else if (tos_type == ftos) {
              obj->float_field_put(field_offset, STACK_FLOAT(-1));
            } else {
              obj->double_field_put(field_offset, STACK_DOUBLE(-1));
            }
          }

          UPDATE_PC_AND_TOS_AND_CONTINUE(3, count);
        }

      CASE(_new): {
        u2 index = Bytes::get_Java_u2(pc+1);
        ConstantPool* constants = istate->method()->constants();
        if (!constants->tag_at(index).is_unresolved_klass()) {
          // Make sure klass is initialized and doesn't have a finalizer
          Klass* entry = constants->slot_at(index).get_klass();
          assert(entry->is_klass(), "Should be resolved klass");
          Klass* k_entry = (Klass*) entry;
          assert(k_entry->oop_is_instance(), "Should be InstanceKlass");
          InstanceKlass* ik = (InstanceKlass*) k_entry;
          if ( ik->is_initialized() && ik->can_be_fastpath_allocated() ) {
            size_t obj_size = ik->size_helper();
            oop result = NULL;
            // If the TLAB isn't pre-zeroed then we'll have to do it
            bool need_zero = !ZeroTLAB;
            if (UseTLAB) {
              result = (oop) THREAD->tlab().allocate(obj_size);
            }
            if (result == NULL) {
              need_zero = true;
              // Try allocate in shared eden
        retry:
              HeapWord* compare_to = *Universe::heap()->top_addr();
              HeapWord* new_top = compare_to + obj_size;
              if (new_top <= *Universe::heap()->end_addr()) {
                if (Atomic::cmpxchg_ptr(new_top, Universe::heap()->top_addr(), compare_to) != compare_to) {
                  goto retry;
                }
                result = (oop) compare_to;
              }
            }
            if (result != NULL) {
              // Initialize object (if nonzero size and need) and then the header
              if (need_zero ) {
                HeapWord* to_zero = (HeapWord*) result + sizeof(oopDesc) / oopSize;
                obj_size -= sizeof(oopDesc) / oopSize;
                if (obj_size > 0 ) {
                  memset(to_zero, 0, obj_size * HeapWordSize);
                }
              }
              if (UseBiasedLocking) {
                result->set_mark(ik->prototype_header());
              } else {
                result->set_mark(markOopDesc::prototype());
              }
              result->set_klass_gap(0);
              result->set_klass(k_entry);
              SET_STACK_OBJECT(result, 0);
              UPDATE_PC_AND_TOS_AND_CONTINUE(3, 1);
            }
          }
        }
        // Slow case allocation
        CALL_VM(InterpreterRuntime::_new(THREAD, METHOD->constants(), index),
                handle_exception);
        SET_STACK_OBJECT(THREAD->vm_result(), 0);
        THREAD->set_vm_result(NULL);
        UPDATE_PC_AND_TOS_AND_CONTINUE(3, 1);
      }
      CASE(_anewarray): {
        u2 index = Bytes::get_Java_u2(pc+1);
        jint size = STACK_INT(-1);
        CALL_VM(InterpreterRuntime::anewarray(THREAD, METHOD->constants(), index, size),
                handle_exception);
        SET_STACK_OBJECT(THREAD->vm_result(), -1);
        THREAD->set_vm_result(NULL);
        UPDATE_PC_AND_CONTINUE(3);
      }
      CASE(_multianewarray): {
        jint dims = *(pc+3);
        jint size = STACK_INT(-1);
        // stack grows down, dimensions are up!
        jint *dimarray =
                   (jint*)&topOfStack[dims * Interpreter::stackElementWords+
                                      Interpreter::stackElementWords-1];
        //adjust pointer to start of stack element
        CALL_VM(InterpreterRuntime::multianewarray(THREAD, dimarray),
                handle_exception);
        SET_STACK_OBJECT(THREAD->vm_result(), -dims);
        THREAD->set_vm_result(NULL);
        UPDATE_PC_AND_TOS_AND_CONTINUE(4, -(dims-1));
      }
      CASE(_checkcast):
          if (STACK_OBJECT(-1) != NULL) {
            VERIFY_OOP(STACK_OBJECT(-1));
            u2 index = Bytes::get_Java_u2(pc+1);
            if (ProfileInterpreter) {
              // needs Profile_checkcast QQQ
              ShouldNotReachHere();
            }
            // Constant pool may have actual klass or unresolved klass. If it is
            // unresolved we must resolve it
            if (METHOD->constants()->tag_at(index).is_unresolved_klass()) {
              CALL_VM(InterpreterRuntime::quicken_io_cc(THREAD), handle_exception);
            }
            Klass* klassOf = (Klass*) METHOD->constants()->slot_at(index).get_klass();
            Klass* objKlassOop = STACK_OBJECT(-1)->klass(); //ebx
            //
            // Check for compatibilty. This check must not GC!!
            // Seems way more expensive now that we must dispatch
            //
            if (objKlassOop != klassOf &&
                !objKlassOop->is_subtype_of(klassOf)) {
              ResourceMark rm(THREAD);
              const char* objName = objKlassOop->external_name();
              const char* klassName = klassOf->external_name();
              char* message = SharedRuntime::generate_class_cast_message(
                objName, klassName);
              VM_JAVA_ERROR(vmSymbols::java_lang_ClassCastException(), message);
            }
          } else {
            if (UncommonNullCast) {
//              istate->method()->set_null_cast_seen();
// [RGV] Not sure what to do here!

            }
          }
          UPDATE_PC_AND_CONTINUE(3);

      CASE(_instanceof):
          if (STACK_OBJECT(-1) == NULL) {
            SET_STACK_INT(0, -1);
          } else {
            VERIFY_OOP(STACK_OBJECT(-1));
            u2 index = Bytes::get_Java_u2(pc+1);
            // Constant pool may have actual klass or unresolved klass. If it is
            // unresolved we must resolve it
            if (METHOD->constants()->tag_at(index).is_unresolved_klass()) {
              CALL_VM(InterpreterRuntime::quicken_io_cc(THREAD), handle_exception);
            }
            Klass* klassOf = (Klass*) METHOD->constants()->slot_at(index).get_klass();
            Klass* objKlassOop = STACK_OBJECT(-1)->klass();
            //
            // Check for compatibilty. This check must not GC!!
            // Seems way more expensive now that we must dispatch
            //
            if ( objKlassOop == klassOf || objKlassOop->is_subtype_of(klassOf)) {
              SET_STACK_INT(1, -1);
            } else {
              SET_STACK_INT(0, -1);
            }
          }
          UPDATE_PC_AND_CONTINUE(3);

      CASE(_ldc_w):
      CASE(_ldc):
        {
          u2 index;
          bool wide = false;
          int incr = 2; // frequent case
          if (opcode == Bytecodes::_ldc) {
            index = pc[1];
          } else {
            index = Bytes::get_Java_u2(pc+1);
            incr = 3;
            wide = true;
          }

          ConstantPool* constants = METHOD->constants();
          switch (constants->tag_at(index).value()) {
          case JVM_CONSTANT_Integer:
            SET_STACK_INT(constants->int_at(index), 0);
            break;

          case JVM_CONSTANT_Float:
            SET_STACK_FLOAT(constants->float_at(index), 0);
            break;

          case JVM_CONSTANT_String:
            {
              oop result = constants->resolved_references()->obj_at(index);
              if (result == NULL) {
                CALL_VM(InterpreterRuntime::resolve_ldc(THREAD, (Bytecodes::Code) opcode), handle_exception);
                SET_STACK_OBJECT(THREAD->vm_result(), 0);
                THREAD->set_vm_result(NULL);
              } else {
                VERIFY_OOP(result);
                SET_STACK_OBJECT(result, 0);
              }
            break;
            }

          case JVM_CONSTANT_Class:
            VERIFY_OOP(constants->resolved_klass_at(index)->java_mirror());
            SET_STACK_OBJECT(constants->resolved_klass_at(index)->java_mirror(), 0);
            break;

          case JVM_CONSTANT_UnresolvedClass:
          case JVM_CONSTANT_UnresolvedClassInError:
            CALL_VM(InterpreterRuntime::ldc(THREAD, wide), handle_exception);
            SET_STACK_OBJECT(THREAD->vm_result(), 0);
            THREAD->set_vm_result(NULL);
            break;

          default:  ShouldNotReachHere();
          }
          UPDATE_PC_AND_TOS_AND_CONTINUE(incr, 1);
        }

      CASE(_ldc2_w):
        {
          u2 index = Bytes::get_Java_u2(pc+1);

          ConstantPool* constants = METHOD->constants();
          switch (constants->tag_at(index).value()) {

          case JVM_CONSTANT_Long:
             SET_STACK_LONG(constants->long_at(index), 1);
            break;

          case JVM_CONSTANT_Double:
             SET_STACK_DOUBLE(constants->double_at(index), 1);
            break;
          default:  ShouldNotReachHere();
          }
          UPDATE_PC_AND_TOS_AND_CONTINUE(3, 2);
        }

      CASE(_fast_aldc_w):
      CASE(_fast_aldc): {
        u2 index;
        int incr;
        if (opcode == Bytecodes::_fast_aldc) {
          index = pc[1];
          incr = 2;
        } else {
          index = Bytes::get_native_u2(pc+1);
          incr = 3;
        }

        // We are resolved if the f1 field contains a non-null object (CallSite, etc.)
        // This kind of CP cache entry does not need to match the flags byte, because
        // there is a 1-1 relation between bytecode type and CP entry type.
        ConstantPool* constants = METHOD->constants();
        oop result = constants->resolved_references()->obj_at(index);
        if (result == NULL) {
          CALL_VM(InterpreterRuntime::resolve_ldc(THREAD, (Bytecodes::Code) opcode),
                  handle_exception);
          result = THREAD->vm_result();
        }

        VERIFY_OOP(result);
        SET_STACK_OBJECT(result, 0);
        UPDATE_PC_AND_TOS_AND_CONTINUE(incr, 1);
      }

      CASE(_invokedynamic): {

        if (!EnableInvokeDynamic) {
          // We should not encounter this bytecode if !EnableInvokeDynamic.
          // The verifier will stop it.  However, if we get past the verifier,
          // this will stop the thread in a reasonable way, without crashing the JVM.
          CALL_VM(InterpreterRuntime::throw_IncompatibleClassChangeError(THREAD),
                  handle_exception);
          ShouldNotReachHere();
        }

        u4 index = Bytes::get_native_u4(pc+1);
        ConstantPoolCacheEntry* cache = cp->constant_pool()->invokedynamic_cp_cache_entry_at(index);

        // We are resolved if the resolved_references field contains a non-null object (CallSite, etc.)
        // This kind of CP cache entry does not need to match the flags byte, because
        // there is a 1-1 relation between bytecode type and CP entry type.
        if (! cache->is_resolved((Bytecodes::Code) opcode)) {
          CALL_VM(InterpreterRuntime::resolve_invokedynamic(THREAD),
                  handle_exception);
          cache = cp->constant_pool()->invokedynamic_cp_cache_entry_at(index);
        }

        Method* method = cache->f1_as_method();
        if (VerifyOops) method->verify();

        if (cache->has_appendix()) {
          ConstantPool* constants = METHOD->constants();
          SET_STACK_OBJECT(cache->appendix_if_resolved(constants), 0);
          MORE_STACK(1);
        }

        istate->set_msg(call_method);
        istate->set_callee(method);
        istate->set_callee_entry_point(method->from_interpreted_entry());
        istate->set_bcp_advance(5);

        UPDATE_PC_AND_RETURN(0); // I'll be back...
      }

      CASE(_invokehandle): {

        if (!EnableInvokeDynamic) {
          ShouldNotReachHere();
        }

        u2 index = Bytes::get_native_u2(pc+1);
        ConstantPoolCacheEntry* cache = cp->entry_at(index);

        if (! cache->is_resolved((Bytecodes::Code) opcode)) {
          CALL_VM(InterpreterRuntime::resolve_invokehandle(THREAD),
                  handle_exception);
          cache = cp->entry_at(index);
        }

        Method* method = cache->f1_as_method();
        if (VerifyOops) method->verify();

        if (cache->has_appendix()) {
          ConstantPool* constants = METHOD->constants();
          SET_STACK_OBJECT(cache->appendix_if_resolved(constants), 0);
          MORE_STACK(1);
        }

        istate->set_msg(call_method);
        istate->set_callee(method);
        istate->set_callee_entry_point(method->from_interpreted_entry());
        istate->set_bcp_advance(3);

        UPDATE_PC_AND_RETURN(0); // I'll be back...
      }

      CASE(_invokeinterface): {
        u2 index = Bytes::get_native_u2(pc+1);

        // QQQ Need to make this as inlined as possible. Probably need to split all the bytecode cases
        // out so c++ compiler has a chance for constant prop to fold everything possible away.

        ConstantPoolCacheEntry* cache = cp->entry_at(index);
        if (!cache->is_resolved((Bytecodes::Code)opcode)) {
          CALL_VM(InterpreterRuntime::resolve_invoke(THREAD, (Bytecodes::Code)opcode),
                  handle_exception);
          cache = cp->entry_at(index);
        }

        istate->set_msg(call_method);

        // Special case of invokeinterface called for virtual method of
        // java.lang.Object.  See cpCacheOop.cpp for details.
        // This code isn't produced by javac, but could be produced by
        // another compliant java compiler.
        if (cache->is_forced_virtual()) {
          Method* callee;
          CHECK_NULL(STACK_OBJECT(-(cache->parameter_size())));
          if (cache->is_vfinal()) {
            callee = cache->f2_as_vfinal_method();
          } else {
            // get receiver
            int parms = cache->parameter_size();
            // Same comments as invokevirtual apply here
            VERIFY_OOP(STACK_OBJECT(-parms));
            InstanceKlass* rcvrKlass = (InstanceKlass*)
                                 STACK_OBJECT(-parms)->klass();
            callee = (Method*) rcvrKlass->start_of_vtable()[ cache->f2_as_index()];
          }
          istate->set_callee(callee);
          istate->set_callee_entry_point(callee->from_interpreted_entry());
#ifdef VM_JVMTI
          if (JvmtiExport::can_post_interpreter_events() && THREAD->is_interp_only_mode()) {
            istate->set_callee_entry_point(callee->interpreter_entry());
          }
#endif /* VM_JVMTI */
          istate->set_bcp_advance(5);
          UPDATE_PC_AND_RETURN(0); // I'll be back...
        }

        // this could definitely be cleaned up QQQ
        Method* callee;
        Klass* iclass = cache->f1_as_klass();
        // InstanceKlass* interface = (InstanceKlass*) iclass;
        // get receiver
        int parms = cache->parameter_size();
        oop rcvr = STACK_OBJECT(-parms);
        CHECK_NULL(rcvr);
        InstanceKlass* int2 = (InstanceKlass*) rcvr->klass();
        itableOffsetEntry* ki = (itableOffsetEntry*) int2->start_of_itable();
        int i;
        for ( i = 0 ; i < int2->itable_length() ; i++, ki++ ) {
          if (ki->interface_klass() == iclass) break;
        }
        // If the interface isn't found, this class doesn't implement this
        // interface.  The link resolver checks this but only for the first
        // time this interface is called.
        if (i == int2->itable_length()) {
          VM_JAVA_ERROR(vmSymbols::java_lang_IncompatibleClassChangeError(), "");
        }
        int mindex = cache->f2_as_index();
        itableMethodEntry* im = ki->first_method_entry(rcvr->klass());
        callee = im[mindex].method();
        if (callee == NULL) {
          VM_JAVA_ERROR(vmSymbols::java_lang_AbstractMethodError(), "");
        }

        istate->set_callee(callee);
        istate->set_callee_entry_point(callee->from_interpreted_entry());
#ifdef VM_JVMTI
        if (JvmtiExport::can_post_interpreter_events() && THREAD->is_interp_only_mode()) {
          istate->set_callee_entry_point(callee->interpreter_entry());
        }
#endif /* VM_JVMTI */
        istate->set_bcp_advance(5);
        UPDATE_PC_AND_RETURN(0); // I'll be back...
      }

      CASE(_invokevirtual):
      CASE(_invokespecial):
      CASE(_invokestatic): {
        u2 index = Bytes::get_native_u2(pc+1);

        ConstantPoolCacheEntry* cache = cp->entry_at(index);
        // QQQ Need to make this as inlined as possible. Probably need to split all the bytecode cases
        // out so c++ compiler has a chance for constant prop to fold everything possible away.

        if (!cache->is_resolved((Bytecodes::Code)opcode)) {
          CALL_VM(InterpreterRuntime::resolve_invoke(THREAD, (Bytecodes::Code)opcode),
                  handle_exception);
          cache = cp->entry_at(index);
        }

        istate->set_msg(call_method);
        {
          Method* callee;
          if ((Bytecodes::Code)opcode == Bytecodes::_invokevirtual) {
            CHECK_NULL(STACK_OBJECT(-(cache->parameter_size())));
            if (cache->is_vfinal()) callee = cache->f2_as_vfinal_method();
            else {
              // get receiver
              int parms = cache->parameter_size();
              // this works but needs a resourcemark and seems to create a vtable on every call:
              // Method* callee = rcvr->klass()->vtable()->method_at(cache->f2_as_index());
              //
              // this fails with an assert
              // InstanceKlass* rcvrKlass = InstanceKlass::cast(STACK_OBJECT(-parms)->klass());
              // but this works
              VERIFY_OOP(STACK_OBJECT(-parms));
              InstanceKlass* rcvrKlass = (InstanceKlass*) STACK_OBJECT(-parms)->klass();
              /*
                Executing this code in java.lang.String:
                    public String(char value[]) {
                          this.count = value.length;
                          this.value = (char[])value.clone();
                     }

                 a find on rcvr->klass() reports:
                 {type array char}{type array class}
                  - klass: {other class}

                  but using InstanceKlass::cast(STACK_OBJECT(-parms)->klass()) causes in assertion failure
                  because rcvr->klass()->oop_is_instance() == 0
                  However it seems to have a vtable in the right location. Huh?

              */
              callee = (Method*) rcvrKlass->start_of_vtable()[ cache->f2_as_index()];
            }
          } else {
            if ((Bytecodes::Code)opcode == Bytecodes::_invokespecial) {
              CHECK_NULL(STACK_OBJECT(-(cache->parameter_size())));
            }
            callee = cache->f1_as_method();
          }

          istate->set_callee(callee);
          istate->set_callee_entry_point(callee->from_interpreted_entry());
#ifdef VM_JVMTI
          if (JvmtiExport::can_post_interpreter_events() && THREAD->is_interp_only_mode()) {
            istate->set_callee_entry_point(callee->interpreter_entry());
          }
#endif /* VM_JVMTI */
          istate->set_bcp_advance(3);
          UPDATE_PC_AND_RETURN(0); // I'll be back...
        }
      }

      /* Allocate memory for a new java object. */

      CASE(_newarray): {
        BasicType atype = (BasicType) *(pc+1);
        jint size = STACK_INT(-1);
        CALL_VM(InterpreterRuntime::newarray(THREAD, atype, size),
                handle_exception);
        SET_STACK_OBJECT(THREAD->vm_result(), -1);
        THREAD->set_vm_result(NULL);

        UPDATE_PC_AND_CONTINUE(2);
      }

      /* Throw an exception. */

      CASE(_athrow): {
          oop except_oop = STACK_OBJECT(-1);
          CHECK_NULL(except_oop);
          // set pending_exception so we use common code
          THREAD->set_pending_exception(except_oop, NULL, 0);
          goto handle_exception;
      }

      /* goto and jsr. They are exactly the same except jsr pushes
       * the address of the next instruction first.
       */

      CASE(_jsr): {
          /* push bytecode index on stack */
          SET_STACK_ADDR(((address)pc - (intptr_t)(istate->method()->code_base()) + 3), 0);
          MORE_STACK(1);
          /* FALL THROUGH */
      }

      CASE(_goto):
      {
          int16_t offset = (int16_t)Bytes::get_Java_u2(pc + 1);
          address branch_pc = pc;
          UPDATE_PC(offset);
          DO_BACKEDGE_CHECKS(offset, branch_pc);
          CONTINUE;
      }

      CASE(_jsr_w): {
          /* push return address on the stack */
          SET_STACK_ADDR(((address)pc - (intptr_t)(istate->method()->code_base()) + 5), 0);
          MORE_STACK(1);
          /* FALL THROUGH */
      }

      CASE(_goto_w):
      {
          int32_t offset = Bytes::get_Java_u4(pc + 1);
          address branch_pc = pc;
          UPDATE_PC(offset);
          DO_BACKEDGE_CHECKS(offset, branch_pc);
          CONTINUE;
      }

      /* return from a jsr or jsr_w */

      CASE(_ret): {
          pc = istate->method()->code_base() + (intptr_t)(LOCALS_ADDR(pc[1]));
          UPDATE_PC_AND_CONTINUE(0);
      }

      /* debugger breakpoint */

      CASE(_breakpoint): {
          Bytecodes::Code original_bytecode;
          DECACHE_STATE();
          SET_LAST_JAVA_FRAME();
          original_bytecode = InterpreterRuntime::get_original_bytecode_at(THREAD,
                              METHOD, pc);
          RESET_LAST_JAVA_FRAME();
          CACHE_STATE();
          if (THREAD->has_pending_exception()) goto handle_exception;
            CALL_VM(InterpreterRuntime::_breakpoint(THREAD, METHOD, pc),
                                                    handle_exception);

          opcode = (jubyte)original_bytecode;
          goto opcode_switch;
      }

      DEFAULT:
          fatal(err_msg("Unimplemented opcode %d = %s", opcode,
                        Bytecodes::name((Bytecodes::Code)opcode)));
          goto finish;

      } /* switch(opc) */


#ifdef USELABELS
    check_for_exception:
#endif
    {
      if (!THREAD->has_pending_exception()) {
        CONTINUE;
      }
      /* We will be gcsafe soon, so flush our state. */
      DECACHE_PC();
      goto handle_exception;
    }
  do_continue: ;

  } /* while (1) interpreter loop */

可以看到,opcode 就是字节码指令中的操作数,根据操作码的不同,case 会进行匹配,调用对应的执行方法。

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