void C1_MacroAssembler::initialize_object(
  Register obj,                        // result: pointer to object after successful allocation
  Register klass,                      // object klass
  Register var_size_in_bytes,          // object size in bytes if unknown at compile time; invalid otherwise
  int      con_size_in_bytes,          // object size in bytes if   known at compile time
  Register t1,                         // temp register
  Register t2                          // temp register
  ) {
  const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;

  initialize_header(obj, klass, noreg, t1, t2);

#ifdef ASSERT
  {
    lwz(t1, in_bytes(Klass::layout_helper_offset()), klass);
    if (var_size_in_bytes != noreg) {
      cmpw(CCR0, t1, var_size_in_bytes);
    } else {
      cmpwi(CCR0, t1, con_size_in_bytes);
    }
    asm_assert_eq("bad size in initialize_object", 0x753);
  }
#endif

  // Initialize body.
  if (var_size_in_bytes != noreg) {
    // Use a loop.
    addi(t1, obj, hdr_size_in_bytes);                // Compute address of first element.
    addi(t2, var_size_in_bytes, -hdr_size_in_bytes); // Compute size of body.
    initialize_body(t1, t2);
  } else if (con_size_in_bytes > hdr_size_in_bytes) {
    // Use a loop.
    initialize_body(obj, t1, t2, con_size_in_bytes, hdr_size_in_bytes);
  }

  if (CURRENT_ENV->dtrace_alloc_probes()) {
    Unimplemented();
//    assert(obj == O0, "must be");
//    call(CAST_FROM_FN_PTR(address, Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)),
//         relocInfo::runtime_call_type);
  }

  verify_oop(obj);
}
address JNI_FastGetField::generate_fast_get_int_field0(BasicType type) {
  const char *name;
  switch (type) {
    case T_BOOLEAN: name = "jni_fast_GetBooleanField"; break;
    case T_BYTE:    name = "jni_fast_GetByteField";    break;
    case T_CHAR:    name = "jni_fast_GetCharField";    break;
    case T_SHORT:   name = "jni_fast_GetShortField";   break;
    case T_INT:     name = "jni_fast_GetIntField";     break;
    case T_LONG:    name = "jni_fast_GetLongField";    break;
    case T_FLOAT:   name = "jni_fast_GetFloatField";   break;
    case T_DOUBLE:  name = "jni_fast_GetDoubleField";  break;
    default:        ShouldNotReachHere();
  }
  ResourceMark rm;
  BufferBlob* blob = BufferBlob::create(name, BUFFER_SIZE);
  CodeBuffer cbuf(blob);
  MacroAssembler* masm = new MacroAssembler(&cbuf);
  address fast_entry = __ pc();

  Label slow;

  unsigned long offset;
  __ adrp(rcounter_addr,
	  SafepointSynchronize::safepoint_counter_addr(), offset);
  Address safepoint_counter_addr(rcounter_addr, offset);
  __ ldrw(rcounter, safepoint_counter_addr);
  __ andw(rscratch1, rcounter, 1);
  __ cbnzw(rscratch1, slow);
  __ eor(robj, c_rarg1, rcounter);
  __ eor(robj, robj, rcounter);               // obj, since
                                              // robj ^ rcounter ^ rcounter == robj
                                              // robj is address dependent on rcounter.
  __ ldr(robj, Address(robj, 0));             // *obj
  __ lsr(roffset, c_rarg2, 2);                // offset

  assert(count < LIST_CAPACITY, "LIST_CAPACITY too small");
  speculative_load_pclist[count] = __ pc();   // Used by the segfault handler
  switch (type) {
    case T_BOOLEAN: __ ldrb    (result, Address(robj, roffset)); break;
    case T_BYTE:    __ ldrsb   (result, Address(robj, roffset)); break;
    case T_CHAR:    __ ldrh    (result, Address(robj, roffset)); break;
    case T_SHORT:   __ ldrsh   (result, Address(robj, roffset)); break;
    case T_FLOAT:   __ ldrw    (result, Address(robj, roffset)); break;
    case T_INT:     __ ldrsw   (result, Address(robj, roffset)); break;
    case T_DOUBLE:
    case T_LONG:    __ ldr     (result, Address(robj, roffset)); break;
    default:        ShouldNotReachHere();
  }

  // counter_addr is address dependent on result.
  __ eor(rcounter_addr, rcounter_addr, result);
  __ eor(rcounter_addr, rcounter_addr, result);
  __ ldrw(rscratch1, safepoint_counter_addr);
  __ cmpw(rcounter, rscratch1);
  __ br (Assembler::NE, slow);

  switch (type) {
    case T_FLOAT:   __ fmovs(v0, result); break;
    case T_DOUBLE:  __ fmovd(v0, result); break;
    default:        __ mov(r0, result);   break;
  }
  __ ret(lr);

  slowcase_entry_pclist[count++] = __ pc();
  __ bind(slow);
  address slow_case_addr;
  switch (type) {
    case T_BOOLEAN: slow_case_addr = jni_GetBooleanField_addr(); break;
    case T_BYTE:    slow_case_addr = jni_GetByteField_addr();    break;
    case T_CHAR:    slow_case_addr = jni_GetCharField_addr();    break;
    case T_SHORT:   slow_case_addr = jni_GetShortField_addr();   break;
    case T_INT:     slow_case_addr = jni_GetIntField_addr();     break;
    case T_LONG:    slow_case_addr = jni_GetLongField_addr();    break;
    case T_FLOAT:   slow_case_addr = jni_GetFloatField_addr();   break;
    case T_DOUBLE:  slow_case_addr = jni_GetDoubleField_addr();  break;
    default:        ShouldNotReachHere();
  }

  {
    __ enter();
    __ lea(rscratch1, ExternalAddress(slow_case_addr));
    __ blr(rscratch1);
    __ maybe_isb();
    __ leave();
    __ ret(lr);
  }
  __ flush ();

  return fast_entry;
}
VtableStub* VtableStubs::create_vtable_stub(int vtable_index) {
  const int aarch64_code_length = VtableStub::pd_code_size_limit(true);
  VtableStub* s = new(aarch64_code_length) VtableStub(true, vtable_index);
  ResourceMark rm;
  CodeBuffer cb(s->entry_point(), aarch64_code_length);
  MacroAssembler* masm = new MacroAssembler(&cb);

#ifndef PRODUCT
  if (CountCompiledCalls) {
    __ lea(r19, ExternalAddress((address) SharedRuntime::nof_megamorphic_calls_addr()));
    __ incrementw(Address(r19));
  }
#endif

  // get receiver (need to skip return address on top of stack)
  assert(VtableStub::receiver_location() == j_rarg0->as_VMReg(), "receiver expected in j_rarg0");

  // get receiver klass
  address npe_addr = __ pc();
  __ load_klass(r19, j_rarg0);

#ifndef PRODUCT
  if (DebugVtables) {
    Label L;
    // check offset vs vtable length
    __ ldrw(rscratch1, Address(r19, Klass::vtable_length_offset()));
    __ cmpw(rscratch1, vtable_index * vtableEntry::size());
    __ br(Assembler::GT, L);
    __ enter();
    __ mov(r2, vtable_index);
    __ call_VM(noreg,
               CAST_FROM_FN_PTR(address, bad_compiled_vtable_index), j_rarg0, r2);
    __ leave();
    __ bind(L);
  }
#endif // PRODUCT

  __ lookup_virtual_method(r19, vtable_index, rmethod);

  if (DebugVtables) {
    Label L;
    __ cbz(rmethod, L);
    __ ldr(rscratch1, Address(rmethod, Method::from_compiled_offset()));
    __ cbnz(rscratch1, L);
    __ stop("Vtable entry is NULL");
    __ bind(L);
  }
  // r0: receiver klass
  // rmethod: Method*
  // r2: receiver
  address ame_addr = __ pc();
  __ ldr(rscratch1, Address(rmethod, Method::from_compiled_offset()));
  __ br(rscratch1);

  __ flush();

  if (PrintMiscellaneous && (WizardMode || Verbose)) {
    tty->print_cr("vtable #%d at " PTR_FORMAT "[%d] left over: %d",
                  vtable_index, p2i(s->entry_point()),
                  (int)(s->code_end() - s->entry_point()),
                  (int)(s->code_end() - __ pc()));
  }
  guarantee(__ pc() <= s->code_end(), "overflowed buffer");

  s->set_exception_points(npe_addr, ame_addr);
  return s;
}
void MethodHandles::generate_method_handle_dispatch(MacroAssembler* _masm,
                                                    vmIntrinsics::ID iid,
                                                    Register receiver_reg,
                                                    Register member_reg,
                                                    bool for_compiler_entry) {
  assert(is_signature_polymorphic(iid), "expected invoke iid");
  // temps used in this code are not used in *either* compiled or interpreted calling sequences
  Register temp1 = r10;
  Register temp2 = r11;
  Register temp3 = r14;  // r13 is live by this point: it contains the sender SP
  if (for_compiler_entry) {
    assert(receiver_reg == (iid == vmIntrinsics::_linkToStatic ? noreg : j_rarg0), "only valid assignment");
    assert_different_registers(temp1,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5, j_rarg6, j_rarg7);
    assert_different_registers(temp2,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5, j_rarg6, j_rarg7);
    assert_different_registers(temp3,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5, j_rarg6, j_rarg7);
  }

  assert_different_registers(temp1, temp2, temp3, receiver_reg);
  assert_different_registers(temp1, temp2, temp3, member_reg);

  if (iid == vmIntrinsics::_invokeBasic) {
    // indirect through MH.form.vmentry.vmtarget
    jump_to_lambda_form(_masm, receiver_reg, rmethod, temp1, for_compiler_entry);

  } else {
    // The method is a member invoker used by direct method handles.
    if (VerifyMethodHandles) {
      // make sure the trailing argument really is a MemberName (caller responsibility)
      verify_klass(_masm, member_reg, SystemDictionary::WK_KLASS_ENUM_NAME(java_lang_invoke_MemberName),
                   "MemberName required for invokeVirtual etc.");
    }

    Address member_clazz(    member_reg, NONZERO(java_lang_invoke_MemberName::clazz_offset_in_bytes()));
    Address member_vmindex(  member_reg, NONZERO(java_lang_invoke_MemberName::vmindex_offset_in_bytes()));
    Address member_vmtarget( member_reg, NONZERO(java_lang_invoke_MemberName::vmtarget_offset_in_bytes()));

    Register temp1_recv_klass = temp1;
    if (iid != vmIntrinsics::_linkToStatic) {
      __ verify_oop(receiver_reg);
      if (iid == vmIntrinsics::_linkToSpecial) {
        // Don't actually load the klass; just null-check the receiver.
        __ null_check(receiver_reg);
      } else {
        // load receiver klass itself
        __ null_check(receiver_reg, oopDesc::klass_offset_in_bytes());
        __ load_klass(temp1_recv_klass, receiver_reg);
        __ verify_klass_ptr(temp1_recv_klass);
      }
      BLOCK_COMMENT("check_receiver {");
      // The receiver for the MemberName must be in receiver_reg.
      // Check the receiver against the MemberName.clazz
      if (VerifyMethodHandles && iid == vmIntrinsics::_linkToSpecial) {
        // Did not load it above...
        __ load_klass(temp1_recv_klass, receiver_reg);
        __ verify_klass_ptr(temp1_recv_klass);
      }
      if (VerifyMethodHandles && iid != vmIntrinsics::_linkToInterface) {
        Label L_ok;
        Register temp2_defc = temp2;
        __ load_heap_oop(temp2_defc, member_clazz);
        load_klass_from_Class(_masm, temp2_defc);
        __ verify_klass_ptr(temp2_defc);
        __ check_klass_subtype(temp1_recv_klass, temp2_defc, temp3, L_ok);
        // If we get here, the type check failed!
        __ hlt(0);
        // __ STOP("receiver class disagrees with MemberName.clazz");
        __ bind(L_ok);
      }
      BLOCK_COMMENT("} check_receiver");
    }
    if (iid == vmIntrinsics::_linkToSpecial ||
        iid == vmIntrinsics::_linkToStatic) {
      DEBUG_ONLY(temp1_recv_klass = noreg);  // these guys didn't load the recv_klass
    }

    // Live registers at this point:
    //  member_reg - MemberName that was the trailing argument
    //  temp1_recv_klass - klass of stacked receiver, if needed
    //  r13 - interpreter linkage (if interpreted)  ??? FIXME
    //  r1 ... r0 - compiler arguments (if compiled)

    Label L_incompatible_class_change_error;
    switch (iid) {
    case vmIntrinsics::_linkToSpecial:
      if (VerifyMethodHandles) {
        verify_ref_kind(_masm, JVM_REF_invokeSpecial, member_reg, temp3);
      }
      __ ldr(rmethod, member_vmtarget);
      break;

    case vmIntrinsics::_linkToStatic:
      if (VerifyMethodHandles) {
        verify_ref_kind(_masm, JVM_REF_invokeStatic, member_reg, temp3);
      }
      __ ldr(rmethod, member_vmtarget);
      break;

    case vmIntrinsics::_linkToVirtual:
    {
      // same as TemplateTable::invokevirtual,
      // minus the CP setup and profiling:

      if (VerifyMethodHandles) {
        verify_ref_kind(_masm, JVM_REF_invokeVirtual, member_reg, temp3);
      }

      // pick out the vtable index from the MemberName, and then we can discard it:
      Register temp2_index = temp2;
      __ ldr(temp2_index, member_vmindex);

      if (VerifyMethodHandles) {
        Label L_index_ok;
        __ cmpw(temp2_index, 0U);
        __ br(Assembler::GE, L_index_ok);
        __ hlt(0);
        __ BIND(L_index_ok);
      }

      // Note:  The verifier invariants allow us to ignore MemberName.clazz and vmtarget
      // at this point.  And VerifyMethodHandles has already checked clazz, if needed.

      // get target Method* & entry point
      __ lookup_virtual_method(temp1_recv_klass, temp2_index, rmethod);
      break;
    }

    case vmIntrinsics::_linkToInterface:
    {
      // same as TemplateTable::invokeinterface
      // (minus the CP setup and profiling, with different argument motion)
      if (VerifyMethodHandles) {
        verify_ref_kind(_masm, JVM_REF_invokeInterface, member_reg, temp3);
      }

      Register temp3_intf = temp3;
      __ load_heap_oop(temp3_intf, member_clazz);
      load_klass_from_Class(_masm, temp3_intf);
      __ verify_klass_ptr(temp3_intf);

      Register rindex = rmethod;
      __ ldr(rindex, member_vmindex);
      if (VerifyMethodHandles) {
        Label L;
        __ cmpw(rindex, 0U);
        __ br(Assembler::GE, L);
        __ hlt(0);
        __ bind(L);
      }

      // given intf, index, and recv klass, dispatch to the implementation method
      __ lookup_interface_method(temp1_recv_klass, temp3_intf,
                                 // note: next two args must be the same:
                                 rindex, rmethod,
                                 temp2,
                                 L_incompatible_class_change_error);
      break;
    }

    default:
      fatal("unexpected intrinsic %d: %s", iid, vmIntrinsics::name_at(iid));
      break;
    }

    // live at this point:  rmethod, r13 (if interpreted)

    // After figuring out which concrete method to call, jump into it.
    // Note that this works in the interpreter with no data motion.
    // But the compiled version will require that r2_recv be shifted out.
    __ verify_method_ptr(rmethod);
    jump_from_method_handle(_masm, rmethod, temp1, for_compiler_entry);
    if (iid == vmIntrinsics::_linkToInterface) {
      __ bind(L_incompatible_class_change_error);
      __ far_jump(RuntimeAddress(StubRoutines::throw_IncompatibleClassChangeError_entry()));
    }
  }
}
Beispiel #5
0
void NativeGenerator::generate_native_string_entries() {

  comment_section("Native entry points for string functions");
  {

    //--------------------java.lang.String.indexof0---------------------------
    rom_linkable_entry("native_string_indexof0_entry");

    wtk_profile_quick_call(/* param_size*/ 2);

    comment("Pop the return address");
    popl(edi);
    comment("Push zero for fromIndex");
    pushl(Constant(0));
    comment("Push back the return address");
    pushl(edi);

    jmp(Constant("native_string_indexof_entry"));
    rom_linkable_entry_end(); // native_string_indexof0_entry

    //--------------------java.lang.String.indexof---------------------------

    rom_linkable_entry("native_string_indexof_entry");
    Label cont, loop, test, failure, success;

    wtk_profile_quick_call(/* param_size*/ 3);

    comment("Pop the return address");
    popl(edi);

    comment("Pop the argument: fromIndex");
    pop_int(eax, eax);

    comment("Pop the argument: ch");
    pop_int(ebx, ebx);

    comment("Pop the receiver");
    pop_obj(ecx, ecx);

    cmpl(ebx, Constant(0xFFFF));
    jcc(greater, Constant(failure));

    cmpl(eax, Constant(0));
    jcc(greater_equal, Constant(cont));
    movl(eax, Constant(0));

    bind(cont);
    movl(esi, Address(ecx, Constant(String::count_offset())));

    comment("if (fromIndex >= count) { return -1; }");
    cmpl(eax, esi);
    jcc(greater_equal, Constant(failure));

    movl(edx, Address(ecx, Constant(String::offset_offset())));
    addl(eax, edx); // i = offset + fromIndex
    addl(edx, esi); // int max = offset + count;
    movl(esi, Address(ecx, Constant(String::value_offset())));    // v = value.
    jmp(Constant(test));

    bind(loop);
    cmpw(Address(esi, eax, times_2, Constant(Array::base_offset())),  ebx);
    jcc(equal, Constant(success));
    incl(eax);

    bind(test);
    cmpl(eax, edx);
    jcc(less, Constant(loop));

    comment("Return -1 by pushing the value and jumping to the return address");
    bind(failure);
    push_int(-1);
    jmp(edi);

    comment("Return i - offset by pushing the value and jumping to the return address");
    bind(success);
    movl(esi, Address(ecx, Constant(String::offset_offset())));   // i = offset + fromIndex
    subl(eax, esi);
    push_int(eax);
    jmp(edi);

    rom_linkable_entry_end(); // native_string_indexof_entry
  }

  //----------------------java.lang.String.charAt---------------------------

  {
    rom_linkable_entry("native_string_charAt_entry");
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }
    rom_linkable_entry_end();
  }

  //----------------------java.lang.String(java.lang.StringBuffer)-------------

  {
    rom_linkable_entry("native_string_init_entry");
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }
    rom_linkable_entry_end();
  }

  //----------------------java.lang.String.equals(java.lang.Object)------------

  {
    rom_linkable_entry("native_string_equals_entry");
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }
    rom_linkable_entry_end();
  }

  //----------------------java.lang.String.indexOf(java.lang.String)-----------

  {
    rom_linkable_entry("native_string_indexof0_string_entry");
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }
    rom_linkable_entry_end();
  }

  //----------------------java.lang.String.indexOf(java.lang.String)-----------

  {
    rom_linkable_entry("native_string_indexof_string_entry");
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }
    rom_linkable_entry_end();
  }

  //----------------------java.lang.String.compareTo---------------------------

  { // java.lang.String.compareTo
    // Method int compareTo(java.lang.String)

    rom_linkable_entry("native_string_compareTo_entry");

    wtk_profile_quick_call(/* param_size*/ 2);

    comment("preserve method");
    pushl(ebx);

    // 8 is return address plus pushed method
    int  str1_offset =  JavaFrame::arg_offset_from_sp(0) + 8,
         str0_offset =  JavaFrame::arg_offset_from_sp(1) + 8;

    comment("load arguments to registers");
    movl(ecx, Address(esp, Constant(str1_offset)));
    movl(eax, Address(esp, Constant(str0_offset)));

    // eax: str0: this String
    // ebx: str1: String to compare against

    Label bailout;

    comment("Null check");
    testl(ecx, ecx);
    jcc(zero, Constant(bailout));

    comment("get str0.value[]");
    movl(esi, Address(eax, Constant(String::value_offset())));
    comment("get str0.offset");
    movl(ebx, Address(eax, Constant(String::offset_offset())));
    comment("compute start of character data");
    leal(esi, Address(esi, ebx, times_2, Constant(Array::base_offset())));
    comment("get str0.count");
    movl(eax, Address(eax, Constant(String::count_offset())));

    comment("get str1.value[]");
    movl(edi, Address(ecx, Constant(String::value_offset())));
    comment("get str1.offset");
    movl(ebx, Address(ecx, Constant(String::offset_offset())));
    comment("compute start of character data");
    leal(edi, Address(edi, ebx, times_2, Constant(Array::base_offset())));
    comment("get str1.count");
    movl(ebx, Address(ecx, Constant(String::count_offset())));

    // esi = str0 start of character data
    // edi = str1 start of character data
    // eax = str0 length
    // ebx = str1 length

    Label str1_longest;
    subl(eax, ebx);
    jcc(greater_equal, Constant(str1_longest));
    // str1 is longer than str0
    addl(ebx, eax);
    bind(str1_longest);

    // esi = str0 start of character data
    // edi = str1 start of character data
    // eax = str0.count - str1.count
    // ebx = min(str0.count, str1.count)

    // save str0.count - str1.count, we might need it later
    pushl(eax);

    xorl(ecx, ecx);

    Label loop, check_lengths, done;
    bind(loop);
    cmpl(ecx, ebx);
    jcc(above_equal, Constant(check_lengths));
    movzxw(eax, Address(esi, ecx, times_2));
    movzxw(edx, Address(edi, ecx, times_2));
    subl(eax, edx);
    jcc(not_equal, Constant(done));
    incl(ecx);
    jmp(Constant(loop));

    bind(check_lengths);
    movl(eax, Address(esp));

    bind(done);
    popl(ebx); // remove saved length difference

    // Push result on stack and return to caller
    popl(ebx);     // remove method
    popl(edi);     // pop return address
    addl(esp, Constant(2 * BytesPerStackElement)); // remove arguments
    push_int(eax); // push result
    jmp(edi);      // return

    comment("Bail out to the general compareTo implementation");
    bind(bailout);
    comment("pop method");
    popl(ebx);
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }

    rom_linkable_entry_end(); // native_string_compareTo_entry
  }

  //----------------------java.lang.String.endsWith----------------

  {
    // java.lang.String.endsWith
    // Method boolean endsWith(java.lang.String)

    rom_linkable_entry("native_string_endsWith_entry");

    wtk_profile_quick_call(/* param_size*/ 2);

    Label bailout;

    // 4 is return address
    int suffix_offset =  JavaFrame::arg_offset_from_sp(0) + 4,
        this_offset =  JavaFrame::arg_offset_from_sp(1) + 4;

    comment("load arguments to registers");
    movl(eax, Address(esp, Constant(suffix_offset)));
    cmpl(eax, Constant(0));
    jcc(equal, Constant(bailout));

    movl(ecx, Address(esp, Constant(this_offset)));

    comment("Pop the return address");
    popl(edi);

    movl(edx, Address(ecx, Constant(String::count_offset())));
    subl(edx, Address(eax, Constant(String::count_offset())));

    comment("Push (this.count - suffix.count) for toffset");
    pushl(edx);

    comment("Push back the return address");
    pushl(edi);

    jmp(Constant("native_string_startsWith_entry"));

    comment("Bail out to the general startsWith implementation");
    bind(bailout);
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }

    rom_linkable_entry_end(); // native_string_endsWith_entry
  }

  //----------------------java.lang.String.startsWith----------------
  {
    // java.lang.String.startsWith
    // Method boolean startsWith(java.lang.String)
    rom_linkable_entry("native_string_startsWith0_entry");

    wtk_profile_quick_call(/* param_size*/ 2);
    Label bailout;

    // 4 is return address
    int prefix_offset = JavaFrame::arg_offset_from_sp(0) + 4;

    comment("Check if prefix is null");
    cmpl(Address(esp, Constant(prefix_offset)), Constant(0));
    jcc(equal, Constant(bailout));

    comment("Pop the return address");
    popl(edi);
    comment("Push zero for toffset");
    pushl(Constant(0));
    comment("Push back the return address");
    pushl(edi);

    jmp(Constant("native_string_startsWith_entry"));

    comment("Bail out to the general startsWith implementation");
    bind(bailout);
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }

    rom_linkable_entry_end(); // native_string_startsWith0_entry
  }

  {
    // ----------- java.lang.String.startsWith ------------------------------
    // Method boolean startsWith(java.lang.String,int)

    rom_linkable_entry("native_string_startsWith_entry");

    wtk_profile_quick_call(/* param_size*/ 3);

    Label bailout, return_false;

    // 4 is return address
    int  prefix_offset =  JavaFrame::arg_offset_from_sp(1) + 4;

    comment("Check if prefix is null");
    cmpl(Address(esp, Constant(prefix_offset)), Constant(0));
    jcc(equal, Constant(bailout));

    comment("Pop the return address");
    popl(edi);

    comment("Pop the argument: toffset");
    pop_int(edx, edx);

    comment("Pop the argument: prefix");
    pop_obj(eax, eax);

    comment("Pop the receiver");
    pop_obj(ecx, ecx);

    comment("Preserve the return address");
    pushl(edi);

    // ecx: this String
    // eax: prefix

    cmpl(edx, Constant(0));
    jcc(less, Constant(return_false));

    comment("if (toffset > this.count - prefix.count) return false;");
    movl(ebx, Address(ecx, Constant(String::count_offset())));
    subl(ebx, Address(eax, Constant(String::count_offset())));
    cmpl(edx, ebx);
    jcc(greater, Constant(return_false));

    comment("get this.value[]");
    movl(esi, Address(ecx, Constant(String::value_offset())));
    comment("get this.offset");
    movl(ebx, Address(ecx, Constant(String::offset_offset())));
    comment("add toffset");
    addl(ebx, edx);
    comment("compute start of character data");
    leal(esi, Address(esi, ebx, times_2, Constant(Array::base_offset())));

    comment("get prefix.value[]");
    movl(edi, Address(eax, Constant(String::value_offset())));
    comment("get prefix.offset");
    movl(ebx, Address(eax, Constant(String::offset_offset())));
    comment("compute start of character data");
    leal(edi, Address(edi, ebx, times_2, Constant(Array::base_offset())));

    comment("get prefix.count");
    movl(ecx, Address(eax, Constant(String::count_offset())));
    comment("get the number of bytes to compare");
    shll(ecx, Constant(1));

    comment("memcmp(edi, esi, ecx);");
    pushl(ecx);
    pushl(esi);
    pushl(edi);

    if (GenerateInlineAsm) {
      // VC++ treats memcmp() as an intrinsic function and would cause
      // reference to memcmp in Interpreter_i386.c to fail to compile.
      call(Constant("memcmp_from_interpreter"));
    } else {
      call(Constant("memcmp"));
    }
    addl(esp, Constant(12));
    cmpl(eax, Constant(0));
    jcc(not_equal, Constant(return_false));

    // Push 1 on stack and return to caller
    popl(edi);     // pop return address
    push_int(1);   // push result
    jmp(edi);      // return

    bind(return_false);
    // Push 0 on stack and return to caller
    popl(edi);     // pop return address
    push_int(0);   // push result
    jmp(edi);      // return

    comment("Bail out to the general startsWith implementation");
    bind(bailout);
    if (AddExternCUnderscore) {
      emit_instruction("jmp _interpreter_method_entry");
    } else {
      emit_instruction("jmp  interpreter_method_entry");
    }

    rom_linkable_entry_end(); // native_string_startsWith_entry
  }
}