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 /*

  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.

  * Copyright 2012, 2013 SAP AG. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "asm/assembler.hpp"

 #include "asm/macroAssembler.inline.hpp"

 #include "interpreter/bytecodeHistogram.hpp"

 #include "interpreter/cppInterpreter.hpp"

 #include "interpreter/interpreter.hpp"

 #include "interpreter/interpreterGenerator.hpp"

 #include "interpreter/interpreterRuntime.hpp"

 #include "oops/arrayOop.hpp"

 #include "oops/methodData.hpp"

 #include "oops/method.hpp"

 #include "oops/oop.inline.hpp"

 #include "prims/jvmtiExport.hpp"

 #include "prims/jvmtiThreadState.hpp"

 #include "runtime/arguments.hpp"

 #include "runtime/deoptimization.hpp"

 #include "runtime/frame.inline.hpp"

 #include "runtime/interfaceSupport.hpp"

 #include "runtime/sharedRuntime.hpp"

 #include "runtime/stubRoutines.hpp"

 #include "runtime/synchronizer.hpp"

 #include "runtime/timer.hpp"

 #include "runtime/vframeArray.hpp"

 #include "utilities/debug.hpp"

 #ifdef SHARK

 #include "shark/shark_globals.hpp"

 #endif

 #ifdef CC_INTERP

 #define __ _masm->

 // Contains is used for identifying interpreter frames during a stack-walk.

 // A frame with a PC in InterpretMethod must be identified as a normal C frame.

 bool CppInterpreter::contains(address pc) {

   return _code->contains(pc);

 }

 #ifdef PRODUCT

 #define BLOCK_COMMENT(str) // nothing

 #else

 #define BLOCK_COMMENT(str) __ block_comment(str)

 #endif

 #define BIND(label) bind(label); BLOCK_COMMENT(#label ":")

 static address interpreter_frame_manager        = NULL;

 static address frame_manager_specialized_return = NULL;

 static address native_entry                     = NULL;

 static address interpreter_return_address       = NULL;

 static address unctrap_frame_manager_entry      = NULL;

 static address deopt_frame_manager_return_atos  = NULL;

 static address deopt_frame_manager_return_btos  = NULL;

 static address deopt_frame_manager_return_itos  = NULL;

 static address deopt_frame_manager_return_ltos  = NULL;

 static address deopt_frame_manager_return_ftos  = NULL;

 static address deopt_frame_manager_return_dtos  = NULL;

 static address deopt_frame_manager_return_vtos  = NULL;

 // A result handler converts/unboxes a native call result into

 // a java interpreter/compiler result. The current frame is an

 // interpreter frame.

 address CppInterpreterGenerator::generate_result_handler_for(BasicType type) {

   return AbstractInterpreterGenerator::generate_result_handler_for(type);

 }

 // tosca based result to c++ interpreter stack based result.

 address CppInterpreterGenerator::generate_tosca_to_stack_converter(BasicType type) {

   //

   // A result is in the native abi result register from a native

   // method call. We need to return this result to the interpreter by

   // pushing the result on the interpreter's stack.

   //

   // Registers alive:

   //   R3_ARG1(R3_RET)/F1_ARG1(F1_RET) - result to move

   //   R4_ARG2                         - address of tos

   //   LR

   //

   // Registers updated:

   //   R3_RET(R3_ARG1)   - address of new tos (== R17_tos for T_VOID)

   //

   int number_of_used_slots = 1;

   const Register tos = R4_ARG2;

   Label done;

   Label is_false;

   address entry = __ pc();

   switch (type) {

   case T_BOOLEAN:

     __ cmpwi(CCR0, R3_RET, 0);

     __ beq(CCR0, is_false);

     __ li(R3_RET, 1);

     __ stw(R3_RET, 0, tos);

     __ b(done);

     __ bind(is_false);

     __ li(R3_RET, 0);

     __ stw(R3_RET, 0, tos);

     break;

   case T_BYTE:

   case T_CHAR:

   case T_SHORT:

   case T_INT:

     __ stw(R3_RET, 0, tos);

     break;

   case T_LONG:

     number_of_used_slots = 2;

     // mark unused slot for debugging

     // long goes to topmost slot

     __ std(R3_RET, -BytesPerWord, tos);

     __ li(R3_RET, 0);

     __ std(R3_RET, 0, tos);

     break;

   case T_OBJECT:

     __ verify_oop(R3_RET);

     __ std(R3_RET, 0, tos);

     break;

   case T_FLOAT:

     __ stfs(F1_RET, 0, tos);

     break;

   case T_DOUBLE:

     number_of_used_slots = 2;

     // mark unused slot for debugging

     __ li(R3_RET, 0);

     __ std(R3_RET, 0, tos);

     // double goes to topmost slot

     __ stfd(F1_RET, -BytesPerWord, tos);

     break;

   case T_VOID:

     number_of_used_slots = 0;

     break;

   default:

     ShouldNotReachHere();

   }

   __ BIND(done);

   // new expression stack top

   __ addi(R3_RET, tos, -BytesPerWord * number_of_used_slots);

   __ blr();

   return entry;

 }

 address CppInterpreterGenerator::generate_stack_to_stack_converter(BasicType type) {

   //

   // Copy the result from the callee's stack to the caller's stack,

   // caller and callee both being interpreted.

   //

   // Registers alive

   //   R3_ARG1        - address of callee's tos + BytesPerWord

   //   R4_ARG2        - address of caller's tos [i.e. free location]

   //   LR

   //

   //   stack grows upwards, memory grows downwards.

   //

   //   [      free         ]  <-- callee's tos

   //   [  optional result  ]  <-- R3_ARG1

   //   [  optional dummy   ]

   //          ...

   //   [      free         ]  <-- caller's tos, R4_ARG2

   //          ...

   // Registers updated

   //   R3_RET(R3_ARG1) - address of caller's new tos

   //

   //   stack grows upwards, memory grows downwards.

   //

   //   [      free         ]  <-- current tos, R3_RET

   //   [  optional result  ]

   //   [  optional dummy   ]

   //          ...

   //

   const Register from = R3_ARG1;

   const Register ret  = R3_ARG1;

   const Register tos  = R4_ARG2;

   const Register tmp1 = R21_tmp1;

   const Register tmp2 = R22_tmp2;

   address entry = __ pc();

   switch (type) {

   case T_BOOLEAN:

   case T_BYTE:

   case T_CHAR:

   case T_SHORT:

   case T_INT:

   case T_FLOAT:

     __ lwz(tmp1, 0, from);

     __ stw(tmp1, 0, tos);

     // New expression stack top.

     __ addi(ret, tos, - BytesPerWord);

     break;

   case T_LONG:

   case T_DOUBLE:

     // Move both entries for debug purposes even though only one is live.

     __ ld(tmp1, BytesPerWord, from);

     __ ld(tmp2, 0, from);

     __ std(tmp1, 0, tos);

     __ std(tmp2, -BytesPerWord, tos);

     // New expression stack top.

     __ addi(ret, tos, - 2 * BytesPerWord); // two slots

     break;

   case T_OBJECT:

     __ ld(tmp1, 0, from);

     __ verify_oop(tmp1);

     __ std(tmp1, 0, tos);

     // New expression stack top.

     __ addi(ret, tos, - BytesPerWord);

     break;

   case T_VOID:

     // New expression stack top.

     __ mr(ret, tos);

     break;

   default:

     ShouldNotReachHere();

   }

   __ blr();

   return entry;

 }

 address CppInterpreterGenerator::generate_stack_to_native_abi_converter(BasicType type) {

   //

   // Load a result from the callee's stack into the caller's expecting

   // return register, callee being interpreted, caller being call stub

   // or jit code.

   //

   // Registers alive

   //   R3_ARG1   - callee expression tos + BytesPerWord

   //   LR

   //

   //   stack grows upwards, memory grows downwards.

   //

   //   [      free         ]  <-- callee's tos

   //   [  optional result  ]  <-- R3_ARG1

   //   [  optional dummy   ]

   //          ...

   //

   // Registers updated

   //   R3_RET(R3_ARG1)/F1_RET - result

   //

   const Register from = R3_ARG1;

   const Register ret = R3_ARG1;

   const FloatRegister fret = F1_ARG1;

   address entry = __ pc();

   // Implemented uniformly for both kinds of endianness. The interpreter

   // implements boolean, byte, char, and short as jint (4 bytes).

   switch (type) {

   case T_BOOLEAN:

   case T_CHAR:

     // zero extension

     __ lwz(ret, 0, from);

     break;

   case T_BYTE:

   case T_SHORT:

   case T_INT:

     // sign extension

     __ lwa(ret, 0, from);

     break;

   case T_LONG:

     __ ld(ret, 0, from);

     break;

   case T_OBJECT:

     __ ld(ret, 0, from);

     __ verify_oop(ret);

     break;

   case T_FLOAT:

     __ lfs(fret, 0, from);

     break;

   case T_DOUBLE:

     __ lfd(fret, 0, from);

     break;

   case T_VOID:

     break;

   default:

     ShouldNotReachHere();

   }

   __ blr();

   return entry;

 }

 address CppInterpreter::return_entry(TosState state, int length, Bytecodes::Code code) {

   assert(interpreter_return_address != NULL, "Not initialized");

   return interpreter_return_address;

 }

 address CppInterpreter::deopt_entry(TosState state, int length) {

   address ret = NULL;

   if (length != 0) {

     switch (state) {

       case atos: ret = deopt_frame_manager_return_atos; break;

       case btos: ret = deopt_frame_manager_return_itos; break;

       case ctos:

       case stos:

       case itos: ret = deopt_frame_manager_return_itos; break;

       case ltos: ret = deopt_frame_manager_return_ltos; break;

       case ftos: ret = deopt_frame_manager_return_ftos; break;

       case dtos: ret = deopt_frame_manager_return_dtos; break;

       case vtos: ret = deopt_frame_manager_return_vtos; break;

       default: ShouldNotReachHere();

     }

   } else {

     ret = unctrap_frame_manager_entry;  // re-execute the bytecode (e.g. uncommon trap, popframe)

   }

   assert(ret != NULL, "Not initialized");

   return ret;

 }

 //

 // Helpers for commoning out cases in the various type of method entries.

 //

 //

 // Registers alive

 //   R16_thread      - JavaThread*

 //   R1_SP           - old stack pointer

 //   R19_method      - callee's Method

 //   R17_tos         - address of caller's tos (prepushed)

 //   R15_prev_state  - address of caller's BytecodeInterpreter or 0

 //   return_pc in R21_tmp15 (only when called within generate_native_entry)

 //

 // Registers updated

 //   R14_state       - address of callee's interpreter state

 //   R1_SP           - new stack pointer

 //   CCR4_is_synced  - current method is synchronized

 //

 void CppInterpreterGenerator::generate_compute_interpreter_state(Label& stack_overflow_return) {

   //

   // Stack layout at this point:

   //

   //   F1      [TOP_IJAVA_FRAME_ABI]              <-- R1_SP

   //           alignment (optional)

   //           [F1's outgoing Java arguments]     <-- R17_tos

   //           ...

   //   F2      [PARENT_IJAVA_FRAME_ABI]

   //            ...

   //=============================================================================

   // Allocate space for locals other than the parameters, the

   // interpreter state, monitors, and the expression stack.

   const Register local_count        = R21_tmp1;

   const Register parameter_count    = R22_tmp2;

   const Register max_stack          = R23_tmp3;

   // Must not be overwritten within this method!

   // const Register return_pc         = R29_tmp9;

   const ConditionRegister is_synced = CCR4_is_synced;

   const ConditionRegister is_native = CCR6;

   const ConditionRegister is_static = CCR7;

   assert(is_synced != is_native, "condition code registers must be distinct");

   assert(is_synced != is_static, "condition code registers must be distinct");

   assert(is_native != is_static, "condition code registers must be distinct");

   {

   // Local registers

   const Register top_frame_size     = R24_tmp4;

   const Register access_flags       = R25_tmp5;

   const Register state_offset       = R26_tmp6;

   Register mem_stack_limit          = R27_tmp7;

   const Register page_size          = R28_tmp8;

   BLOCK_COMMENT("compute_interpreter_state {");

   // access_flags = method->access_flags();

   // TODO: PPC port: assert(4 == methodOopDesc::sz_access_flags(), "unexpected field size");

   __ lwa(access_flags, method_(access_flags));

   // parameter_count = method->constMethod->size_of_parameters();

   // TODO: PPC port: assert(2 == ConstMethod::sz_size_of_parameters(), "unexpected field size");

   __ ld(max_stack, in_bytes(Method::const_offset()), R19_method);   // Max_stack holds constMethod for a while.

   __ lhz(parameter_count, in_bytes(ConstMethod::size_of_parameters_offset()), max_stack);

   // local_count = method->constMethod()->max_locals();

   // TODO: PPC port: assert(2 == ConstMethod::sz_max_locals(), "unexpected field size");

   __ lhz(local_count, in_bytes(ConstMethod::size_of_locals_offset()), max_stack);

   // max_stack = method->constMethod()->max_stack();

   // TODO: PPC port: assert(2 == ConstMethod::sz_max_stack(), "unexpected field size");

   __ lhz(max_stack, in_bytes(ConstMethod::max_stack_offset()), max_stack);

   if (EnableInvokeDynamic) {

     // Take into account 'extra_stack_entries' needed by method handles (see method.hpp).

     __ addi(max_stack, max_stack, Method::extra_stack_entries());

   }

   // mem_stack_limit = thread->stack_limit();

   __ ld(mem_stack_limit, thread_(stack_overflow_limit));

   // Point locals at the first argument. Method's locals are the

   // parameters on top of caller's expression stack.

   // tos points past last Java argument

   __ sldi(R18_locals, parameter_count, Interpreter::logStackElementSize);

   __ add(R18_locals, R17_tos, R18_locals);

   // R18_locals - i*BytesPerWord points to i-th Java local (i starts at 0)

   // Set is_native, is_synced, is_static - will be used later.

   __ testbitdi(is_native, R0, access_flags, JVM_ACC_NATIVE_BIT);

   __ testbitdi(is_synced, R0, access_flags, JVM_ACC_SYNCHRONIZED_BIT);

   assert(is_synced->is_nonvolatile(), "is_synced must be non-volatile");

   __ testbitdi(is_static, R0, access_flags, JVM_ACC_STATIC_BIT);

   // PARENT_IJAVA_FRAME_ABI

   //

   // frame_size =

   //   round_to((local_count - parameter_count)*BytesPerWord +

   //              2*BytesPerWord +

   //              alignment +

   //              frame::interpreter_frame_cinterpreterstate_size_in_bytes()

   //              sizeof(PARENT_IJAVA_FRAME_ABI)

   //              method->is_synchronized() ? sizeof(BasicObjectLock) : 0 +

   //              max_stack*BytesPerWord,

   //            16)

   //

   // Note that this calculation is exactly mirrored by

   // AbstractInterpreter::layout_activation_impl() [ and

   // AbstractInterpreter::size_activation() ]. Which is used by

   // deoptimization so that it can allocate the proper sized

   // frame. This only happens for interpreted frames so the extra

   // notes below about max_stack below are not important. The other

   // thing to note is that for interpreter frames other than the

   // current activation the size of the stack is the size of the live

   // portion of the stack at the particular bcp and NOT the maximum

   // stack that the method might use.

   //

   // If we're calling a native method, we replace max_stack (which is

   // zero) with space for the worst-case signature handler varargs

   // vector, which is:

   //

   //   max_stack = max(Argument::n_register_parameters, parameter_count+2);

   //

   // We add two slots to the parameter_count, one for the jni

   // environment and one for a possible native mirror.  We allocate

   // space for at least the number of ABI registers, even though

   // InterpreterRuntime::slow_signature_handler won't write more than

   // parameter_count+2 words when it creates the varargs vector at the

   // top of the stack.  The generated slow signature handler will just

   // load trash into registers beyond the necessary number.  We're

   // still going to cut the stack back by the ABI register parameter

   // count so as to get SP+16 pointing at the ABI outgoing parameter

   // area, so we need to allocate at least that much even though we're

   // going to throw it away.

   //

   // Adjust max_stack for native methods:

   Label skip_native_calculate_max_stack;

   __ bfalse(is_native, skip_native_calculate_max_stack);

   // if (is_native) {

   //  max_stack = max(Argument::n_register_parameters, parameter_count+2);

   __ addi(max_stack, parameter_count, 2*Interpreter::stackElementWords);

   __ cmpwi(CCR0, max_stack, Argument::n_register_parameters);

   __ bge(CCR0, skip_native_calculate_max_stack);

   __ li(max_stack,  Argument::n_register_parameters);

   // }

   __ bind(skip_native_calculate_max_stack);

   // max_stack is now in bytes

   __ slwi(max_stack, max_stack, Interpreter::logStackElementSize);

   // Calculate number of non-parameter locals (in slots):

   Label not_java;

   __ btrue(is_native, not_java);

   // if (!is_native) {

   //   local_count = non-parameter local count

   __ sub(local_count, local_count, parameter_count);

   // } else {

   //   // nothing to do: method->max_locals() == 0 for native methods

   // }

   __ bind(not_java);

   // Calculate top_frame_size and parent_frame_resize.

   {

   const Register parent_frame_resize = R12_scratch2;

   BLOCK_COMMENT("Compute top_frame_size.");

   // top_frame_size = TOP_IJAVA_FRAME_ABI

   //                  + size of interpreter state

   __ li(top_frame_size, frame::top_ijava_frame_abi_size

                         + frame::interpreter_frame_cinterpreterstate_size_in_bytes());

   //                  + max_stack

   __ add(top_frame_size, top_frame_size, max_stack);

   //                  + stack slots for a BasicObjectLock for synchronized methods

   {

     Label not_synced;

     __ bfalse(is_synced, not_synced);

     __ addi(top_frame_size, top_frame_size, frame::interpreter_frame_monitor_size_in_bytes());

     __ bind(not_synced);

   }

   // align

   __ round_to(top_frame_size, frame::alignment_in_bytes);

   BLOCK_COMMENT("Compute parent_frame_resize.");

   // parent_frame_resize = R1_SP - R17_tos

   __ sub(parent_frame_resize, R1_SP, R17_tos);

   //__ li(parent_frame_resize, 0);

   //                       + PARENT_IJAVA_FRAME_ABI

   //                       + extra two slots for the no-parameter/no-locals

   //                         method result

   __ addi(parent_frame_resize, parent_frame_resize,

                                       frame::parent_ijava_frame_abi_size

                                     + 2*Interpreter::stackElementSize);

   //                       + (locals_count - params_count)

   __ sldi(R0, local_count, Interpreter::logStackElementSize);

   __ add(parent_frame_resize, parent_frame_resize, R0);

   // align

   __ round_to(parent_frame_resize, frame::alignment_in_bytes);

   //

   // Stack layout at this point:

   //

   // The new frame F0 hasn't yet been pushed, F1 is still the top frame.

   //

   //   F0      [TOP_IJAVA_FRAME_ABI]

   //           alignment (optional)

   //           [F0's full operand stack]

   //           [F0's monitors] (optional)

   //           [F0's BytecodeInterpreter object]

   //   F1      [PARENT_IJAVA_FRAME_ABI]

   //           alignment (optional)

   //           [F0's Java result]

   //           [F0's non-arg Java locals]

   //           [F1's outgoing Java arguments]     <-- R17_tos

   //           ...

   //   F2      [PARENT_IJAVA_FRAME_ABI]

   //            ...

   // Calculate new R14_state

   // and

   // test that the new memory stack pointer is above the limit,

   // throw a StackOverflowError otherwise.

   __ sub(R11_scratch1/*F1's SP*/,  R1_SP, parent_frame_resize);

   __ addi(R14_state, R11_scratch1/*F1's SP*/,

               -frame::interpreter_frame_cinterpreterstate_size_in_bytes());

   __ sub(R11_scratch1/*F0's SP*/,

              R11_scratch1/*F1's SP*/, top_frame_size);

   BLOCK_COMMENT("Test for stack overflow:");

   __ cmpld(CCR0/*is_stack_overflow*/, R11_scratch1, mem_stack_limit);

   __ blt(CCR0/*is_stack_overflow*/, stack_overflow_return);

   //=============================================================================

   // Frame_size doesn't overflow the stack. Allocate new frame and

   // initialize interpreter state.

   // Register state

   //

   //   R15            - local_count

   //   R16            - parameter_count

   //   R17            - max_stack

   //

   //   R18            - frame_size

   //   R19            - access_flags

   //   CCR4_is_synced - is_synced

   //

   //   GR_Lstate      - pointer to the uninitialized new BytecodeInterpreter.

   // _last_Java_pc just needs to be close enough that we can identify

   // the frame as an interpreted frame. It does not need to be the

   // exact return address from either calling

   // BytecodeInterpreter::InterpretMethod or the call to a jni native method.

   // So we can initialize it here with a value of a bundle in this

   // code fragment. We only do this initialization for java frames

   // where InterpretMethod needs a a way to get a good pc value to

   // store in the thread state. For interpreter frames used to call

   // jni native code we just zero the value in the state and move an

   // ip as needed in the native entry code.

   //

   // const Register last_Java_pc_addr     = GR24_SCRATCH;  // QQQ 27

   // const Register last_Java_pc          = GR26_SCRATCH;

   // Must reference stack before setting new SP since Windows

   // will not be able to deliver the exception on a bad SP.

   // Windows also insists that we bang each page one at a time in order

   // for the OS to map in the reserved pages. If we bang only

   // the final page, Windows stops delivering exceptions to our

   // VectoredExceptionHandler and terminates our program.

   // Linux only requires a single bang but it's rare to have

   // to bang more than 1 page so the code is enabled for both OS's.

   // BANG THE STACK

   //

   // Nothing to do for PPC, because updating the SP will automatically

   // bang the page.

   // Up to here we have calculated the delta for the new C-frame and

   // checked for a stack-overflow. Now we can savely update SP and

   // resize the C-frame.

   // R14_state has already been calculated.

   __ push_interpreter_frame(top_frame_size, parent_frame_resize,

                             R25_tmp5, R26_tmp6, R27_tmp7, R28_tmp8);

   }

   //

   // Stack layout at this point:

   //

   //   F0 has been been pushed!

   //

   //   F0      [TOP_IJAVA_FRAME_ABI]              <-- R1_SP

   //           alignment (optional)               (now it's here, if required)

   //           [F0's full operand stack]

   //           [F0's monitors] (optional)

   //           [F0's BytecodeInterpreter object]

   //   F1      [PARENT_IJAVA_FRAME_ABI]

   //           alignment (optional)               (now it's here, if required)

   //           [F0's Java result]

   //           [F0's non-arg Java locals]

   //           [F1's outgoing Java arguments]

   //           ...

   //   F2      [PARENT_IJAVA_FRAME_ABI]

   //           ...

   //

   // R14_state points to F0's BytecodeInterpreter object.

   //

   }

   //=============================================================================

   // new BytecodeInterpreter-object is save, let's initialize it:

   BLOCK_COMMENT("New BytecodeInterpreter-object is save.");

   {

   // Locals

   const Register bytecode_addr = R24_tmp4;

   const Register constants     = R25_tmp5;

   const Register tos           = R26_tmp6;

   const Register stack_base    = R27_tmp7;

   const Register local_addr    = R28_tmp8;

   {

     Label L;

     __ btrue(is_native, L);

     // if (!is_native) {

       // bytecode_addr = constMethod->codes();

       __ ld(bytecode_addr, method_(const));

       __ addi(bytecode_addr, bytecode_addr, in_bytes(ConstMethod::codes_offset()));

     // }

     __ bind(L);

   }

   __ ld(constants, in_bytes(Method::const_offset()), R19_method);

   __ ld(constants, in_bytes(ConstMethod::constants_offset()), constants);

   // state->_prev_link = prev_state;

   __ std(R15_prev_state, state_(_prev_link));

   // For assertions only.

   // TODO: not needed anyway because it coincides with `_monitor_base'. remove!

   // state->_self_link = state;

   DEBUG_ONLY(__ std(R14_state, state_(_self_link));)

   // state->_thread = thread;

   __ std(R16_thread, state_(_thread));

   // state->_method = method;

   __ std(R19_method, state_(_method));

   // state->_locals = locals;

   __ std(R18_locals, state_(_locals));

   // state->_oop_temp = NULL;

   __ li(R0, 0);

   __ std(R0, state_(_oop_temp));

   // state->_last_Java_fp = *R1_SP // Use *R1_SP as fp

   __ ld(R0, _abi(callers_sp), R1_SP);

   __ std(R0, state_(_last_Java_fp));

   BLOCK_COMMENT("load Stack base:");

   {

     // Stack_base.

     // if (!method->synchronized()) {

     //   stack_base = state;

     // } else {

     //   stack_base = (uintptr_t)state - sizeof(BasicObjectLock);

     // }

     Label L;

     __ mr(stack_base, R14_state);

     __ bfalse(is_synced, L);

     __ addi(stack_base, stack_base, -frame::interpreter_frame_monitor_size_in_bytes());

     __ bind(L);

   }

   // state->_mdx = NULL;

   __ li(R0, 0);

   __ std(R0, state_(_mdx));

   {

     // if (method->is_native()) state->_bcp = NULL;

     // else state->_bcp = bytecode_addr;

     Label label1, label2;

     __ bfalse(is_native, label1);

     __ std(R0, state_(_bcp));

     __ b(label2);

     __ bind(label1);

     __ std(bytecode_addr, state_(_bcp));

     __ bind(label2);

   }

   // state->_result._to_call._callee = NULL;

   __ std(R0, state_(_result._to_call._callee));

   // state->_monitor_base = state;

   __ std(R14_state, state_(_monitor_base));

   // state->_msg = BytecodeInterpreter::method_entry;

   __ li(R0, BytecodeInterpreter::method_entry);

   __ stw(R0, state_(_msg));

   // state->_last_Java_sp = R1_SP;

   __ std(R1_SP, state_(_last_Java_sp));

   // state->_stack_base = stack_base;

   __ std(stack_base, state_(_stack_base));

   // tos = stack_base - 1 slot (prepushed);

   // state->_stack.Tos(tos);

   __ addi(tos, stack_base, - Interpreter::stackElementSize);

   __ std(tos,  state_(_stack));

   {

     BLOCK_COMMENT("get last_Java_pc:");

     // if (!is_native) state->_last_Java_pc = <some_ip_in_this_code_buffer>;

     // else state->_last_Java_pc = NULL; (just for neatness)

     Label label1, label2;

     __ btrue(is_native, label1);

     __ get_PC_trash_LR(R0);

     __ std(R0, state_(_last_Java_pc));

     __ b(label2);

     __ bind(label1);

     __ li(R0, 0);

     __ std(R0, state_(_last_Java_pc));

     __ bind(label2);

   }

   // stack_limit = tos - max_stack;

   __ sub(R0, tos, max_stack);

   // state->_stack_limit = stack_limit;

   __ std(R0, state_(_stack_limit));

   // cache = method->constants()->cache();

    __ ld(R0, ConstantPool::cache_offset_in_bytes(), constants);

   // state->_constants = method->constants()->cache();

   __ std(R0, state_(_constants));

   //=============================================================================

   // synchronized method, allocate and initialize method object lock.

   // if (!method->is_synchronized()) goto fill_locals_with_0x0s;

   Label fill_locals_with_0x0s;

   __ bfalse(is_synced, fill_locals_with_0x0s);

   //   pool_holder = method->constants()->pool_holder();

   const int mirror_offset = in_bytes(Klass::java_mirror_offset());

   {

     Label label1, label2;

     // lockee = NULL; for java methods, correct value will be inserted in BytecodeInterpretMethod.hpp

     __ li(R0,0);

     __ bfalse(is_native, label2);

     __ bfalse(is_static, label1);

     // if (method->is_static()) lockee =

     // pool_holder->klass_part()->java_mirror();

     __ ld(R11_scratch1/*pool_holder*/, ConstantPool::pool_holder_offset_in_bytes(), constants);

     __ ld(R0/*lockee*/, mirror_offset, R11_scratch1/*pool_holder*/);

     __ b(label2);

     __ bind(label1);

     // else lockee = *(oop*)locals;

     __ ld(R0/*lockee*/, 0, R18_locals);

     __ bind(label2);

     // monitor->set_obj(lockee);

     __ std(R0/*lockee*/, BasicObjectLock::obj_offset_in_bytes(), stack_base);

   }

   // See if we need to zero the locals

   __ BIND(fill_locals_with_0x0s);

   //=============================================================================

   // fill locals with 0x0s

   Label locals_zeroed;

   __ btrue(is_native, locals_zeroed);

   if (true /* zerolocals */ || ClearInterpreterLocals) {

     // local_count is already num_locals_slots - num_param_slots

     __ sldi(R0, parameter_count, Interpreter::logStackElementSize);

     __ sub(local_addr, R18_locals, R0);

     __ cmpdi(CCR0, local_count, 0);

     __ ble(CCR0, locals_zeroed);

     __ mtctr(local_count);

     //__ ld_const_addr(R0, (address) 0xcafe0000babe);

     __ li(R0, 0);

     Label zero_slot;

     __ bind(zero_slot);

     // first local is at local_addr

     __ std(R0, 0, local_addr);

     __ addi(local_addr, local_addr, -BytesPerWord);

     __ bdnz(zero_slot);

   }

    __ BIND(locals_zeroed);

   }

   BLOCK_COMMENT("} compute_interpreter_state");

 }

 // Generate code to initiate compilation on invocation counter overflow.

 void CppInterpreterGenerator::generate_counter_overflow(Label& continue_entry) {

   // Registers alive

   //   R14_state

   //   R16_thread

   //

   // Registers updated

   //   R14_state

   //   R3_ARG1 (=R3_RET)

   //   R4_ARG2

   // After entering the vm we remove the activation and retry the

   // entry point in case the compilation is complete.

   // InterpreterRuntime::frequency_counter_overflow takes one argument

   // that indicates if the counter overflow occurs at a backwards

   // branch (NULL bcp). We pass zero. The call returns the address

   // of the verified entry point for the method or NULL if the

   // compilation did not complete (either went background or bailed

   // out).

   __ li(R4_ARG2, 0);

   // Pass false to call_VM so it doesn't check for pending exceptions,

   // since at this point in the method invocation the exception

   // handler would try to exit the monitor of synchronized methods

   // which haven't been entered yet.

   //

   // Returns verified_entry_point or NULL, we don't care which.

   //

   // Do not use the variant `frequency_counter_overflow' that returns

   // a structure, because this will change the argument list by a

   // hidden parameter (gcc 4.1).

   __ call_VM(noreg,

              CAST_FROM_FN_PTR(address, InterpreterRuntime::frequency_counter_overflow),

              R4_ARG2,

              false);

   // Returns verified_entry_point or NULL, we don't care which as we ignore it

   // and run interpreted.

   // Reload method, it may have moved.

   __ ld(R19_method, state_(_method));

   // We jump now to the label "continue_after_compile".

   __ b(continue_entry);

 }

 // Increment invocation count and check for overflow.

 //

 // R19_method must contain Method* of method to profile.

 void CppInterpreterGenerator::generate_counter_incr(Label& overflow) {

   Label done;

   const Register Rcounters             = R12_scratch2;

   const Register iv_be_count           = R11_scratch1;

   const Register invocation_limit      = R12_scratch2;

   const Register invocation_limit_addr = invocation_limit;

   // Load and ev. allocate MethodCounters object.

   __ get_method_counters(R19_method, Rcounters, done);

   // Update standard invocation counters.

   __ increment_invocation_counter(Rcounters, iv_be_count, R0);

   // Compare against limit.

   BLOCK_COMMENT("Compare counter against limit:");

   assert(4 == sizeof(InvocationCounter::InterpreterInvocationLimit),

          "must be 4 bytes");

   __ load_const(invocation_limit_addr, (address)&InvocationCounter::InterpreterInvocationLimit);

   __ lwa(invocation_limit, 0, invocation_limit_addr);

   __ cmpw(CCR0, iv_be_count, invocation_limit);

   __ bge(CCR0, overflow);

   __ bind(done);

 }

 //

 // Call a JNI method.

 //

 // Interpreter stub for calling a native method. (C++ interpreter)

 // This sets up a somewhat different looking stack for calling the native method

 // than the typical interpreter frame setup.

 //

 address CppInterpreterGenerator::generate_native_entry(void) {

   if (native_entry != NULL) return native_entry;

   address entry = __ pc();

   // Read

   //   R16_thread

   //   R15_prev_state  - address of caller's BytecodeInterpreter, if this snippet

   //                     gets called by the frame manager.

   //   R19_method      - callee's Method

   //   R17_tos         - address of caller's tos

   //   R1_SP           - caller's stack pointer

   //   R21_sender_SP   - initial caller sp

   //

   // Update

   //   R14_state       - address of caller's BytecodeInterpreter

   //   R3_RET          - integer result, if any.

   //   F1_RET          - float result, if any.

   //

   //

   // Stack layout at this point:

   //

   //    0       [TOP_IJAVA_FRAME_ABI]         <-- R1_SP

   //            alignment (optional)

   //            [outgoing Java arguments]     <-- R17_tos

   //            ...

   //    PARENT  [PARENT_IJAVA_FRAME_ABI]

   //            ...

   //

   const bool inc_counter = UseCompiler || CountCompiledCalls;

   const Register signature_handler_fd   = R21_tmp1;

   const Register pending_exception      = R22_tmp2;

   const Register result_handler_addr    = R23_tmp3;

   const Register native_method_fd       = R24_tmp4;

   const Register access_flags           = R25_tmp5;

   const Register active_handles         = R26_tmp6;

   const Register sync_state             = R27_tmp7;

   const Register sync_state_addr        = sync_state;     // Address is dead after use.

   const Register suspend_flags          = R24_tmp4;

   const Register return_pc              = R28_tmp8;       // Register will be locked for some time.

   const ConditionRegister is_synced     = CCR4_is_synced; // Live-on-exit from compute_interpreter_state.

   // R1_SP still points to caller's SP at this point.

   // Save initial_caller_sp to caller's abi. The caller frame must be

   // resized before returning to get rid of the c2i arguments (if

   // any).

   // Override the saved SP with the senderSP so we can pop c2i

   // arguments (if any) off when we return

   __ std(R21_sender_SP, _top_ijava_frame_abi(initial_caller_sp), R1_SP);

   // Save LR to caller's frame. We don't use _abi(lr) here, because it is not safe.

   __ mflr(return_pc);

   __ std(return_pc, _top_ijava_frame_abi(frame_manager_lr), R1_SP);

   assert(return_pc->is_nonvolatile(), "return_pc must be a non-volatile register");

   __ verify_method_ptr(R19_method);

   //=============================================================================

   // If this snippet gets called by the frame manager (at label

   // `call_special'), then R15_prev_state is valid. If this snippet

   // is not called by the frame manager, but e.g. by the call stub or

   // by compiled code, then R15_prev_state is invalid.

   {

     // Set R15_prev_state to 0 if we don't return to the frame

     // manager; we will return to the call_stub or to compiled code

     // instead. If R15_prev_state is 0 there will be only one

     // interpreter frame (we will set this up later) in this C frame!

     // So we must take care about retrieving prev_state_(_prev_link)

     // and restoring R1_SP when popping that interpreter.

     Label prev_state_is_valid;

     __ load_const(R11_scratch1/*frame_manager_returnpc_addr*/, (address)&frame_manager_specialized_return);

     __ ld(R12_scratch2/*frame_manager_returnpc*/, 0, R11_scratch1/*frame_manager_returnpc_addr*/);

     __ cmpd(CCR0, return_pc, R12_scratch2/*frame_manager_returnpc*/);

     __ beq(CCR0, prev_state_is_valid);

     __ li(R15_prev_state, 0);

     __ BIND(prev_state_is_valid);

   }

   //=============================================================================

   // Allocate new frame and initialize interpreter state.

   Label exception_return;

   Label exception_return_sync_check;

   Label stack_overflow_return;

   // Generate new interpreter state and jump to stack_overflow_return in case of

   // a stack overflow.

   generate_compute_interpreter_state(stack_overflow_return);

   //=============================================================================

   // Increment invocation counter. On overflow, entry to JNI method

   // will be compiled.

   Label invocation_counter_overflow;

   if (inc_counter) {

     generate_counter_incr(invocation_counter_overflow);

   }

   Label continue_after_compile;

   __ BIND(continue_after_compile);

   // access_flags = method->access_flags();

   // Load access flags.

   assert(access_flags->is_nonvolatile(),

          "access_flags must be in a non-volatile register");

   // Type check.

   // TODO: PPC port: assert(4 == methodOopDesc::sz_access_flags(), "unexpected field size");

   __ lwz(access_flags, method_(access_flags));

   // We don't want to reload R19_method and access_flags after calls

   // to some helper functions.

   assert(R19_method->is_nonvolatile(), "R19_method must be a non-volatile register");

   // Check for synchronized methods. Must happen AFTER invocation counter

   // check, so method is not locked if counter overflows.

   {

     Label method_is_not_synced;

     // Is_synced is still alive.

     assert(is_synced->is_nonvolatile(), "is_synced must be non-volatile");

     __ bfalse(is_synced, method_is_not_synced);

     lock_method();

     // Reload method, it may have moved.

     __ ld(R19_method, state_(_method));

     __ BIND(method_is_not_synced);

   }

   // jvmti/jvmpi support

   __ notify_method_entry();

   // Reload method, it may have moved.

   __ ld(R19_method, state_(_method));

   //=============================================================================

   // Get and call the signature handler

   __ ld(signature_handler_fd, method_(signature_handler));

   Label call_signature_handler;

   __ cmpdi(CCR0, signature_handler_fd, 0);

   __ bne(CCR0, call_signature_handler);

   // Method has never been called. Either generate a specialized

   // handler or point to the slow one.

   //

   // Pass parameter 'false' to avoid exception check in call_VM.

   __ call_VM(noreg, CAST_FROM_FN_PTR(address, InterpreterRuntime::prepare_native_call), R19_method, false);

   // Check for an exception while looking up the target method. If we

   // incurred one, bail.

   __ ld(pending_exception, thread_(pending_exception));

   __ cmpdi(CCR0, pending_exception, 0);

   __ bne(CCR0, exception_return_sync_check); // has pending exception

   // reload method

   __ ld(R19_method, state_(_method));

   // Reload signature handler, it may have been created/assigned in the meanwhile

   __ ld(signature_handler_fd, method_(signature_handler));

   __ BIND(call_signature_handler);

   // Before we call the signature handler we push a new frame to

   // protect the interpreter frame volatile registers when we return

   // from jni but before we can get back to Java.

   // First set the frame anchor while the SP/FP registers are

   // convenient and the slow signature handler can use this same frame

   // anchor.

   // We have a TOP_IJAVA_FRAME here, which belongs to us.

   __ set_top_ijava_frame_at_SP_as_last_Java_frame(R1_SP, R12_scratch2/*tmp*/);

   // Now the interpreter frame (and its call chain) have been

   // invalidated and flushed. We are now protected against eager

   // being enabled in native code. Even if it goes eager the

   // registers will be reloaded as clean and we will invalidate after

   // the call so no spurious flush should be possible.

   // Call signature handler and pass locals address.

   //

   // Our signature handlers copy required arguments to the C stack

   // (outgoing C args), R3_ARG1 to R10_ARG8, and F1_ARG1 to

   // F13_ARG13.

   __ mr(R3_ARG1, R18_locals);

   __ ld(signature_handler_fd, 0, signature_handler_fd);

   __ call_stub(signature_handler_fd);

   // reload method

   __ ld(R19_method, state_(_method));

   // Remove the register parameter varargs slots we allocated in

   // compute_interpreter_state. SP+16 ends up pointing to the ABI

   // outgoing argument area.

   //

   // Not needed on PPC64.

   //__ add(SP, SP, Argument::n_register_parameters*BytesPerWord);

   assert(result_handler_addr->is_nonvolatile(), "result_handler_addr must be in a non-volatile register");

   // Save across call to native method.

   __ mr(result_handler_addr, R3_RET);

   // Set up fixed parameters and call the native method.

   // If the method is static, get mirror into R4_ARG2.

   {

     Label method_is_not_static;

     // access_flags is non-volatile and still, no need to restore it

     // restore access flags

     __ testbitdi(CCR0, R0, access_flags, JVM_ACC_STATIC_BIT);

     __ bfalse(CCR0, method_is_not_static);

     // constants = method->constants();

     __ ld(R11_scratch1, in_bytes(Method::const_offset()), R19_method);

     __ ld(R11_scratch1/*constants*/, in_bytes(ConstMethod::constants_offset()), R11_scratch1);

     // pool_holder = method->constants()->pool_holder();

     __ ld(R11_scratch1/*pool_holder*/, ConstantPool::pool_holder_offset_in_bytes(),

           R11_scratch1/*constants*/);

     const int mirror_offset = in_bytes(Klass::java_mirror_offset());

     // mirror = pool_holder->klass_part()->java_mirror();

     __ ld(R0/*mirror*/, mirror_offset, R11_scratch1/*pool_holder*/);

     // state->_native_mirror = mirror;

     __ std(R0/*mirror*/, state_(_oop_temp));

     // R4_ARG2 = &state->_oop_temp;

     __ addir(R4_ARG2, state_(_oop_temp));

     __ BIND(method_is_not_static);

   }

   // At this point, arguments have been copied off the stack into

   // their JNI positions. Oops are boxed in-place on the stack, with

   // handles copied to arguments. The result handler address is in a

   // register.

   // pass JNIEnv address as first parameter

   __ addir(R3_ARG1, thread_(jni_environment));

   // Load the native_method entry before we change the thread state.

   __ ld(native_method_fd, method_(native_function));

   //=============================================================================

   // Transition from _thread_in_Java to _thread_in_native. As soon as

   // we make this change the safepoint code needs to be certain that

   // the last Java frame we established is good. The pc in that frame

   // just needs to be near here not an actual return address.

   // We use release_store_fence to update values like the thread state, where

   // we don't want the current thread to continue until all our prior memory

   // accesses (including the new thread state) are visible to other threads.

   __ li(R0, _thread_in_native);

   __ release();

   // TODO: PPC port: assert(4 == JavaThread::sz_thread_state(), "unexpected field size");

   __ stw(R0, thread_(thread_state));

   if (UseMembar) {

     __ fence();

   }

   //=============================================================================

   // Call the native method. Argument registers must not have been

   // overwritten since "__ call_stub(signature_handler);" (except for

   // ARG1 and ARG2 for static methods)

   __ call_c(native_method_fd);

   __ std(R3_RET, state_(_native_lresult));

   __ stfd(F1_RET, state_(_native_fresult));

   // The frame_manager_lr field, which we use for setting the last

   // java frame, gets overwritten by the signature handler. Restore

   // it now.

   __ get_PC_trash_LR(R11_scratch1);

   __ std(R11_scratch1, _top_ijava_frame_abi(frame_manager_lr), R1_SP);

   // Because of GC R19_method may no longer be valid.

   // Block, if necessary, before resuming in _thread_in_Java state.

   // In order for GC to work, don't clear the last_Java_sp until after

   // blocking.

   //=============================================================================

   // Switch thread to "native transition" state before reading the

   // synchronization state.  This additional state is necessary

   // because reading and testing the synchronization state is not

   // atomic w.r.t. GC, as this scenario demonstrates: Java thread A,

   // in _thread_in_native state, loads _not_synchronized and is

   // preempted.  VM thread changes sync state to synchronizing and

   // suspends threads for GC. Thread A is resumed to finish this

   // native method, but doesn't block here since it didn't see any

   // synchronization in progress, and escapes.

   // We use release_store_fence to update values like the thread state, where

   // we don't want the current thread to continue until all our prior memory

   // accesses (including the new thread state) are visible to other threads.

   __ li(R0/*thread_state*/, _thread_in_native_trans);

   __ release();

   __ stw(R0/*thread_state*/, thread_(thread_state));

   if (UseMembar) {

     __ fence();

   }

   // Write serialization page so that the VM thread can do a pseudo remote

   // membar. We use the current thread pointer to calculate a thread

   // specific offset to write to within the page. This minimizes bus

   // traffic due to cache line collision.

   else {

     __ serialize_memory(R16_thread, R11_scratch1, R12_scratch2);

   }

   // Now before we return to java we must look for a current safepoint

   // (a new safepoint can not start since we entered native_trans).

   // We must check here because a current safepoint could be modifying

   // the callers registers right this moment.

   // Acquire isn't strictly necessary here because of the fence, but

   // sync_state is declared to be volatile, so we do it anyway.

   __ load_const(sync_state_addr, SafepointSynchronize::address_of_state());

   // TODO: PPC port: assert(4 == SafepointSynchronize::sz_state(), "unexpected field size");

   __ lwz(sync_state, 0, sync_state_addr);

   // TODO: PPC port: assert(4 == Thread::sz_suspend_flags(), "unexpected field size");

   __ lwz(suspend_flags, thread_(suspend_flags));

   __ acquire();

   Label sync_check_done;

   Label do_safepoint;

   // No synchronization in progress nor yet synchronized

   __ cmpwi(CCR0, sync_state, SafepointSynchronize::_not_synchronized);

   // not suspended

   __ cmpwi(CCR1, suspend_flags, 0);

   __ bne(CCR0, do_safepoint);

   __ beq(CCR1, sync_check_done);

   __ bind(do_safepoint);

   // Block.  We do the call directly and leave the current

   // last_Java_frame setup undisturbed.  We must save any possible

   // native result acrosss the call. No oop is present

   __ mr(R3_ARG1, R16_thread);

   __ call_c(CAST_FROM_FN_PTR(FunctionDescriptor*, JavaThread::check_special_condition_for_native_trans),

             relocInfo::none);

   __ bind(sync_check_done);

   //=============================================================================

   // <<<<<< Back in Interpreter Frame >>>>>

   // We are in thread_in_native_trans here and back in the normal

   // interpreter frame. We don't have to do anything special about

   // safepoints and we can switch to Java mode anytime we are ready.

   // Note: frame::interpreter_frame_result has a dependency on how the

   // method result is saved across the call to post_method_exit. For

   // native methods it assumes that the non-FPU/non-void result is

   // saved in _native_lresult and a FPU result in _native_fresult. If

   // this changes then the interpreter_frame_result implementation

   // will need to be updated too.

   // On PPC64, we have stored the result directly after the native call.

   //=============================================================================

   // back in Java

   // We use release_store_fence to update values like the thread state, where

   // we don't want the current thread to continue until all our prior memory

   // accesses (including the new thread state) are visible to other threads.

   __ li(R0/*thread_state*/, _thread_in_Java);

   __ release();

   __ stw(R0/*thread_state*/, thread_(thread_state));

   if (UseMembar) {

     __ fence();

   }

   __ reset_last_Java_frame();

   // Reload GR27_method, call killed it. We can't look at

   // state->_method until we're back in java state because in java

   // state gc can't happen until we get to a safepoint.

   //

   // We've set thread_state to _thread_in_Java already, so restoring

   // R19_method from R14_state works; R19_method is invalid, because

   // GC may have happened.

   __ ld(R19_method, state_(_method)); // reload method, may have moved

   // jvmdi/jvmpi support. Whether we've got an exception pending or

   // not, and whether unlocking throws an exception or not, we notify

   // on native method exit. If we do have an exception, we'll end up

   // in the caller's context to handle it, so if we don't do the

   // notify here, we'll drop it on the floor.

   __ notify_method_exit(true/*native method*/,

                         ilgl /*illegal state (not used for native methods)*/);

   //=============================================================================

   // Handle exceptions

   // See if we must unlock.

   //

   {

     Label method_is_not_synced;

     // is_synced is still alive

     assert(is_synced->is_nonvolatile(), "is_synced must be non-volatile");

     __ bfalse(is_synced, method_is_not_synced);

     unlock_method();

     __ bind(method_is_not_synced);

   }

   // Reset active handles after returning from native.

   // thread->active_handles()->clear();

   __ ld(active_handles, thread_(active_handles));

   // JNIHandleBlock::_top is an int.

   // TODO:  PPC port: assert(4 == JNIHandleBlock::top_size_in_bytes(), "unexpected field size");

   __ li(R0, 0);

   __ stw(R0, JNIHandleBlock::top_offset_in_bytes(), active_handles);

   Label no_pending_exception_from_native_method;

   __ ld(R0/*pending_exception*/, thread_(pending_exception));

   __ cmpdi(CCR0, R0/*pending_exception*/, 0);

   __ beq(CCR0, no_pending_exception_from_native_method);

   //-----------------------------------------------------------------------------

   // An exception is pending. We call into the runtime only if the

   // caller was not interpreted. If it was interpreted the

   // interpreter will do the correct thing. If it isn't interpreted

   // (call stub/compiled code) we will change our return and continue.

   __ BIND(exception_return);

   Label return_to_initial_caller_with_pending_exception;

   __ cmpdi(CCR0, R15_prev_state, 0);

   __ beq(CCR0, return_to_initial_caller_with_pending_exception);

   // We are returning to an interpreter activation, just pop the state,

   // pop our frame, leave the exception pending, and return.

   __ pop_interpreter_state(/*prev_state_may_be_0=*/false);

   __ pop_interpreter_frame(R11_scratch1, R12_scratch2, R21_tmp1 /* set to return pc */, R22_tmp2);

   __ mtlr(R21_tmp1);

   __ blr();

   __ BIND(exception_return_sync_check);

   assert(is_synced->is_nonvolatile(), "is_synced must be non-volatile");

   __ bfalse(is_synced, exception_return);

   unlock_method();

   __ b(exception_return);

   __ BIND(return_to_initial_caller_with_pending_exception);

   // We are returning to a c2i-adapter / call-stub, get the address of the

   // exception handler, pop the frame and return to the handler.

   // First, pop to caller's frame.

   __ pop_interpreter_frame(R11_scratch1, R12_scratch2, R21_tmp1  /* set to return pc */, R22_tmp2);

   __ push_frame_abi112(0, R11_scratch1);

   // Get the address of the exception handler.

   __ call_VM_leaf(CAST_FROM_FN_PTR(address, SharedRuntime::exception_handler_for_return_address),

                   R16_thread,

                   R21_tmp1 /* return pc */);

   __ pop_frame();

   // Load the PC of the the exception handler into LR.

   __ mtlr(R3_RET);

   // Load exception into R3_ARG1 and clear pending exception in thread.

   __ ld(R3_ARG1/*exception*/, thread_(pending_exception));

   __ li(R4_ARG2, 0);

   __ std(R4_ARG2, thread_(pending_exception));

   // Load the original return pc into R4_ARG2.

   __ mr(R4_ARG2/*issuing_pc*/, R21_tmp1);

   // Resize frame to get rid of a potential extension.

   __ resize_frame_to_initial_caller(R11_scratch1, R12_scratch2);

   // Return to exception handler.

   __ blr();

   //-----------------------------------------------------------------------------

   // No exception pending.

   __ BIND(no_pending_exception_from_native_method);

   // Move native method result back into proper registers and return.

   // Invoke result handler (may unbox/promote).

   __ ld(R3_RET, state_(_native_lresult));

   __ lfd(F1_RET, state_(_native_fresult));

   __ call_stub(result_handler_addr);

   // We have created a new BytecodeInterpreter object, now we must destroy it.

   //

   // Restore previous R14_state and caller's SP.  R15_prev_state may

   // be 0 here, because our caller may be the call_stub or compiled

   // code.

   __ pop_interpreter_state(/*prev_state_may_be_0=*/true);

   __ pop_interpreter_frame(R11_scratch1, R12_scratch2, R21_tmp1 /* set to return pc */, R22_tmp2);

   // Resize frame to get rid of a potential extension.

   __ resize_frame_to_initial_caller(R11_scratch1, R12_scratch2);

   // Must use the return pc which was loaded from the caller's frame

   // as the VM uses return-pc-patching for deoptimization.

   __ mtlr(R21_tmp1);

   __ blr();

   //=============================================================================

   // We encountered an exception while computing the interpreter

   // state, so R14_state isn't valid. Act as if we just returned from

   // the callee method with a pending exception.

   __ BIND(stack_overflow_return);

   //

   // Register state:

   //   R14_state         invalid; trashed by compute_interpreter_state

   //   R15_prev_state    valid, but may be 0

   //

   //   R1_SP             valid, points to caller's SP; wasn't yet updated by

   //                     compute_interpreter_state

   //

   // Create exception oop and make it pending.

   // Throw the exception via RuntimeStub "throw_StackOverflowError_entry".

   //

   // Previously, we called C-Code directly. As a consequence, a

   // possible GC tried to process the argument oops of the top frame

   // (see RegisterMap::clear, which sets the corresponding flag to

   // true). This lead to crashes because:

   //   1. The top register map did not contain locations for the argument registers

   //   2. The arguments are dead anyway, could be already overwritten in the worst case

   // Solution: Call via special runtime stub that pushes it's own

   // frame. This runtime stub has the flag "CodeBlob::caller_must_gc_arguments()"

   // set to "false", what prevents the dead arguments getting GC'd.

   //

   // 2 cases exist:

   // 1. We were called by the c2i adapter / call stub

   // 2. We were called by the frame manager

   //

   // Both cases are handled by this code:

   // 1. - initial_caller_sp was saved in both cases on entry, so it's safe to load it back even if it was not changed.

   //    - control flow will be:

   //      throw_stackoverflow_stub->VM->throw_stackoverflow_stub->forward_excep->excp_blob of caller method

   // 2. - control flow will be:

   //      throw_stackoverflow_stub->VM->throw_stackoverflow_stub->forward_excep->rethrow_excp_entry of frame manager->resume_method

   //      Since we restored the caller SP above, the rethrow_excp_entry can restore the original interpreter state

   //      registers using the stack and resume the calling method with a pending excp.

   // Pop any c2i extension from the stack, restore LR just to be sure

   __ ld(R0, _top_ijava_frame_abi(frame_manager_lr), R1_SP);

   __ mtlr(R0);

   // Resize frame to get rid of a potential extension.

   __ resize_frame_to_initial_caller(R11_scratch1, R12_scratch2);

   // Load target address of the runtime stub.

   __ load_const(R12_scratch2, (StubRoutines::throw_StackOverflowError_entry()));

   __ mtctr(R12_scratch2);

   __ bctr();

   //=============================================================================

   // Counter overflow.

   if (inc_counter) {

     // Handle invocation counter overflow

     __ bind(invocation_counter_overflow);

     generate_counter_overflow(continue_after_compile);

   }

   native_entry = entry;

   return entry;

 }

 bool AbstractInterpreter::can_be_compiled(methodHandle m) {

   // No special entry points that preclude compilation.

   return true;

 }

 // Unlock the current method.

 //

 void CppInterpreterGenerator::unlock_method(void) {

   // Find preallocated monitor and unlock method. Method monitor is

   // the first one.

   // Registers alive

   //   R14_state

   //

   // Registers updated

   //   volatiles

   //

   const Register monitor = R4_ARG2;

   // Pass address of initial monitor we allocated.

   //

   // First monitor.

   __ addi(monitor, R14_state, -frame::interpreter_frame_monitor_size_in_bytes());

   // Unlock method

   __ unlock_object(monitor);

 }

 // Lock the current method.

 //

 void CppInterpreterGenerator::lock_method(void) {

   // Find preallocated monitor and lock method. Method monitor is the

   // first one.

   //

   // Registers alive

   //   R14_state

   //

   // Registers updated

   //   volatiles

   //

   const Register monitor = R4_ARG2;

   const Register object  = R5_ARG3;

   // Pass address of initial monitor we allocated.

   __ addi(monitor, R14_state, -frame::interpreter_frame_monitor_size_in_bytes());

   // Pass object address.

   __ ld(object, BasicObjectLock::obj_offset_in_bytes(), monitor);

   // Lock method.

   __ lock_object(monitor, object);

 }

 // Generate code for handling resuming a deopted method.

 void CppInterpreterGenerator::generate_deopt_handling(Register result_index) {

   //=============================================================================

   // Returning from a compiled method into a deopted method. The

   // bytecode at the bcp has completed. The result of the bytecode is

   // in the native abi (the tosca for the template based

   // interpreter). Any stack space that was used by the bytecode that

   // has completed has been removed (e.g. parameters for an invoke) so

   // all that we have to do is place any pending result on the

   // expression stack and resume execution on the next bytecode.

   Label return_from_deopt_common;

   // R3_RET and F1_RET are live here! Load the array index of the

   // required result stub address and continue at return_from_deopt_common.

   // Deopt needs to jump to here to enter the interpreter (return a result).

   deopt_frame_manager_return_atos = __ pc();

   __ li(result_index, AbstractInterpreter::BasicType_as_index(T_OBJECT));

   __ b(return_from_deopt_common);

   deopt_frame_manager_return_btos = __ pc();

   __ li(result_index, AbstractInterpreter::BasicType_as_index(T_BOOLEAN));

   __ b(return_from_deopt_common);

   deopt_frame_manager_return_itos = __ pc();

   __ li(result_index, AbstractInterpreter::BasicType_as_index(T_INT));

   __ b(return_from_deopt_common);

   deopt_frame_manager_return_ltos = __ pc();

   __ li(result_index, AbstractInterpreter::BasicType_as_index(T_LONG));

   __ b(return_from_deopt_common);

   deopt_frame_manager_return_ftos = __ pc();

   __ li(result_index, AbstractInterpreter::BasicType_as_index(T_FLOAT));

   __ b(return_from_deopt_common);

   deopt_frame_manager_return_dtos = __ pc();

   __ li(result_index, AbstractInterpreter::BasicType_as_index(T_DOUBLE));

   __ b(return_from_deopt_common);

   deopt_frame_manager_return_vtos = __ pc();

   __ li(result_index, AbstractInterpreter::BasicType_as_index(T_VOID));

   // Last one, fall-through to return_from_deopt_common.

   // Deopt return common. An index is present that lets us move any

   // possible result being return to the interpreter's stack.

   //

   __ BIND(return_from_deopt_common);

 }

 // Generate the code to handle a more_monitors message from the c++ interpreter.

 void CppInterpreterGenerator::generate_more_monitors() {

   //

   // Registers alive

   //   R16_thread      - JavaThread*

   //   R15_prev_state  - previous BytecodeInterpreter or 0

   //   R14_state       - BytecodeInterpreter* address of receiver's interpreter state

   //   R1_SP           - old stack pointer

   //

   // Registers updated

   //   R1_SP          - new stack pointer

   //

   // Very-local scratch registers.

   const Register old_tos         = R21_tmp1;

   const Register new_tos         = R22_tmp2;

   const Register stack_base      = R23_tmp3;

   const Register stack_limit     = R24_tmp4;

   const Register slot            = R25_tmp5;

   const Register n_slots         = R25_tmp5;

   // Interpreter state fields.

   const Register msg             = R24_tmp4;

   // Load up relevant interpreter state.

   __ ld(stack_base, state_(_stack_base));                // Old stack_base

   __ ld(old_tos, state_(_stack));                        // Old tos

   __ ld(stack_limit, state_(_stack_limit));              // Old stack_limit

   // extracted monitor_size

   int monitor_size = frame::interpreter_frame_monitor_size_in_bytes();

   assert(Assembler::is_aligned((unsigned int)monitor_size,

                                (unsigned int)frame::alignment_in_bytes),

          "size of a monitor must respect alignment of SP");

   // Save and restore top LR

   __ ld(R12_scratch2, _top_ijava_frame_abi(frame_manager_lr), R1_SP);

   __ resize_frame(-monitor_size, R11_scratch1);// Allocate space for new monitor

   __ std(R12_scratch2, _top_ijava_frame_abi(frame_manager_lr), R1_SP);

     // Initial_caller_sp is used as unextended_sp for non initial callers.

   __ std(R1_SP, _top_ijava_frame_abi(initial_caller_sp), R1_SP);

   __ addi(stack_base, stack_base, -monitor_size);        // New stack_base

   __ addi(new_tos, old_tos, -monitor_size);              // New tos

   __ addi(stack_limit, stack_limit, -monitor_size);      // New stack_limit

   __ std(R1_SP, state_(_last_Java_sp));                  // Update frame_bottom

   __ std(stack_base, state_(_stack_base));               // Update stack_base

   __ std(new_tos, state_(_stack));                       // Update tos

   __ std(stack_limit, state_(_stack_limit));             // Update stack_limit

   __ li(msg, BytecodeInterpreter::got_monitors);         // Tell interpreter we allocated the lock

   __ stw(msg, state_(_msg));

   // Shuffle expression stack down. Recall that stack_base points

   // just above the new expression stack bottom. Old_tos and new_tos

   // are used to scan thru the old and new expression stacks.

   Label copy_slot, copy_slot_finished;

   __ sub(n_slots, stack_base, new_tos);

   __ srdi_(n_slots, n_slots, LogBytesPerWord);           // compute number of slots to copy

   assert(LogBytesPerWord == 3, "conflicts assembler instructions");

   __ beq(CCR0, copy_slot_finished);                       // nothing to copy

   __ mtctr(n_slots);

   // loop

   __ bind(copy_slot);

   __ ldu(slot, BytesPerWord, old_tos);                   // slot = *++old_tos;

   __ stdu(slot, BytesPerWord, new_tos);                  // *++new_tos = slot;

   __ bdnz(copy_slot);

   __ bind(copy_slot_finished);

   // Restart interpreter

   __ li(R0, 0);

   __ std(R0, BasicObjectLock::obj_offset_in_bytes(), stack_base);  // Mark lock as unused

 }

 address CppInterpreterGenerator::generate_normal_entry(void) {

   if (interpreter_frame_manager != NULL) return interpreter_frame_manager;

   address entry = __ pc();

   address return_from_native_pc = (address) NULL;

   // Initial entry to frame manager (from call_stub or c2i_adapter)

   //

   // Registers alive

   //   R16_thread               - JavaThread*

   //   R19_method               - callee's Method (method to be invoked)

   //   R17_tos                  - address of sender tos (prepushed)

   //   R1_SP                    - SP prepared by call stub such that caller's outgoing args are near top

   //   LR                       - return address to caller (call_stub or c2i_adapter)

   //   R21_sender_SP            - initial caller sp

   //

   // Registers updated

   //   R15_prev_state           - 0

   //

   // Stack layout at this point:

   //

   //   0       [TOP_IJAVA_FRAME_ABI]         <-- R1_SP

   //           alignment (optional)

   //           [outgoing Java arguments]     <-- R17_tos

   //           ...

   //   PARENT  [PARENT_IJAVA_FRAME_ABI]

   //           ...

   //

   // Save initial_caller_sp to caller's abi.

   // The caller frame must be resized before returning to get rid of

   // the c2i part on top of the calling compiled frame (if any).

   // R21_tmp1 must match sender_sp in gen_c2i_adapter.

   // Now override the saved SP with the senderSP so we can pop c2i

   // arguments (if any) off when we return.

   __ std(R21_sender_SP, _top_ijava_frame_abi(initial_caller_sp), R1_SP);

   // Save LR to caller's frame. We don't use _abi(lr) here,

   // because it is not safe.

   __ mflr(R0);

   __ std(R0, _top_ijava_frame_abi(frame_manager_lr), R1_SP);

   // If we come here, it is the first invocation of the frame manager.

   // So there is no previous interpreter state.

   __ li(R15_prev_state, 0);

   // Fall through to where "recursive" invocations go.

   //=============================================================================

   // Dispatch an instance of the interpreter. Recursive activations

   // come here.

   Label re_dispatch;

   __ BIND(re_dispatch);

   //

   // Registers alive

   //    R16_thread        - JavaThread*

   //    R19_method        - callee's Method

   //    R17_tos           - address of caller's tos (prepushed)

   //    R15_prev_state    - address of caller's BytecodeInterpreter or 0

   //    R1_SP             - caller's SP trimmed such that caller's outgoing args are near top.

   //

   // Stack layout at this point:

   //

   //   0       [TOP_IJAVA_FRAME_ABI]

   //           alignment (optional)

   //           [outgoing Java arguments]

   //           ...

   //   PARENT  [PARENT_IJAVA_FRAME_ABI]

   //           ...

   // fall through to interpreted execution

   //=============================================================================

   // Allocate a new Java frame and initialize the new interpreter state.

   Label stack_overflow_return;

   // Create a suitable new Java frame plus a new BytecodeInterpreter instance

   // in the current (frame manager's) C frame.

   generate_compute_interpreter_state(stack_overflow_return);

   // fall through

   //=============================================================================

   // Interpreter dispatch.

   Label call_interpreter;

   __ BIND(call_interpreter);

   //

   // Registers alive

   //   R16_thread       - JavaThread*

   //   R15_prev_state   - previous BytecodeInterpreter or 0

   //   R14_state        - address of receiver's BytecodeInterpreter

   //   R1_SP            - receiver's stack pointer

   //

   // Thread fields.

   const Register pending_exception = R21_tmp1;

   // Interpreter state fields.

   const Register msg               = R24_tmp4;

   // MethodOop fields.

   const Register parameter_count   = R25_tmp5;

   const Register result_index      = R26_tmp6;

   const Register dummy             = R28_tmp8;

   // Address of various interpreter stubs.

   // R29_tmp9 is reserved.

   const Register stub_addr         = R27_tmp7;

   // Uncommon trap needs to jump to here to enter the interpreter

   // (re-execute current bytecode).

   unctrap_frame_manager_entry  = __ pc();

   // If we are profiling, store our fp (BSP) in the thread so we can

   // find it during a tick.

   if (Arguments::has_profile()) {

     // On PPC64 we store the pointer to the current BytecodeInterpreter,

     // instead of the bsp of ia64. This should suffice to be able to

     // find all interesting information.

     __ std(R14_state, thread_(last_interpreter_fp));

   }

   // R16_thread, R14_state and R15_prev_state are nonvolatile

   // registers. There is no need to save these. If we needed to save

   // some state in the current Java frame, this could be a place to do

   // so.

   // Call Java bytecode dispatcher passing "BytecodeInterpreter* istate".

   __ call_VM_leaf(CAST_FROM_FN_PTR(address,

                                    JvmtiExport::can_post_interpreter_events()

                                    ? BytecodeInterpreter::runWithChecks

                                    : BytecodeInterpreter::run),

                   R14_state);

   interpreter_return_address  = __ last_calls_return_pc();

   // R16_thread, R14_state and R15_prev_state have their values preserved.

   // If we are profiling, clear the fp in the thread to tell

   // the profiler that we are no longer in the interpreter.

   if (Arguments::has_profile()) {

     __ li(R11_scratch1, 0);

     __ std(R11_scratch1, thread_(last_interpreter_fp));

   }

   // Load message from bytecode dispatcher.

   // TODO: PPC port: guarantee(4 == BytecodeInterpreter::sz_msg(), "unexpected field size");

   __ lwz(msg, state_(_msg));

   Label more_monitors;

   Label return_from_native;

   Label return_from_native_common;

   Label return_from_native_no_exception;

   Label return_from_interpreted_method;

   Label return_from_recursive_activation;

   Label unwind_recursive_activation;

   Label resume_interpreter;

   Label return_to_initial_caller;

   Label unwind_initial_activation;

   Label unwind_initial_activation_pending_exception;

   Label call_method;

   Label call_special;

   Label retry_method;

   Label retry_method_osr;

   Label popping_frame;

   Label throwing_exception;

   // Branch according to the received message

   __ cmpwi(CCR1, msg, BytecodeInterpreter::call_method);

   __ cmpwi(CCR2, msg, BytecodeInterpreter::return_from_method);

   __ beq(CCR1, call_method);

   __ beq(CCR2, return_from_interpreted_method);

   __ cmpwi(CCR3, msg, BytecodeInterpreter::more_monitors);

   __ cmpwi(CCR4, msg, BytecodeInterpreter::throwing_exception);

   __ beq(CCR3, more_monitors);

   __ beq(CCR4, throwing_exception);

   __ cmpwi(CCR5, msg, BytecodeInterpreter::popping_frame);

   __ cmpwi(CCR6, msg, BytecodeInterpreter::do_osr);

   __ beq(CCR5, popping_frame);

   __ beq(CCR6, retry_method_osr);

   __ stop("bad message from interpreter");

   //=============================================================================

   // Add a monitor just below the existing one(s). State->_stack_base

   // points to the lowest existing one, so we insert the new one just

   // below it and shuffle the expression stack down. Ref. the above

   // stack layout picture, we must update _stack_base, _stack, _stack_limit

   // and _last_Java_sp in the interpreter state.

   __ BIND(more_monitors);

   generate_more_monitors();

   __ b(call_interpreter);

   generate_deopt_handling(result_index);

   // Restoring the R14_state is already done by the deopt_blob.

   // Current tos includes no parameter slots.

   __ ld(R17_tos, state_(_stack));

   __ li(msg, BytecodeInterpreter::deopt_resume);

   __ b(return_from_native_common);

   // We are sent here when we are unwinding from a native method or

   // adapter with an exception pending. We need to notify the interpreter

   // that there is an exception to process.

   // We arrive here also if the frame manager called an (interpreted) target

   // which returns with a StackOverflow exception.

   // The control flow is in this case is:

   // frame_manager->throw_excp_stub->forward_excp->rethrow_excp_entry

   AbstractInterpreter::_rethrow_exception_entry = __ pc();

   // Restore R14_state.

   __ ld(R14_state, 0, R1_SP);

   __ addi(R14_state, R14_state,

               -frame::interpreter_frame_cinterpreterstate_size_in_bytes());

   // Store exception oop into thread object.

   __ std(R3_RET, thread_(pending_exception));

   __ li(msg, BytecodeInterpreter::method_resume /*rethrow_exception*/);

   //

   // NOTE: the interpreter frame as setup be deopt does NOT include

   // any parameter slots (good thing since we have no callee here

   // and couldn't remove them) so we don't have to do any calculations

   // here to figure it out.

   //

   __ ld(R17_tos, state_(_stack));

   __ b(return_from_native_common);

   //=============================================================================

   // Returning from a native method.  Result is in the native abi

   // location so we must move it to the java expression stack.

   __ BIND(return_from_native);

   guarantee(return_from_native_pc == (address) NULL, "precondition");

   return_from_native_pc = __ pc();

   // Restore R14_state.

   __ ld(R14_state, 0, R1_SP);

   __ addi(R14_state, R14_state,

               -frame::interpreter_frame_cinterpreterstate_size_in_bytes());

   //

   // Registers alive

   //   R16_thread

   //   R14_state    - address of caller's BytecodeInterpreter.

   //   R3_RET       - integer result, if any.

   //   F1_RET       - float result, if any.

   //

   // Registers updated

   //   R19_method   - callee's Method

   //   R17_tos      - caller's tos, with outgoing args popped

   //   result_index - index of result handler.

   //   msg          - message for resuming interpreter.

   //

   // Very-local scratch registers.

   const ConditionRegister have_pending_exception = CCR0;

   // Load callee Method, gc may have moved it.

   __ ld(R19_method, state_(_result._to_call._callee));

   // Load address of caller's tos. includes parameter slots.

   __ ld(R17_tos, state_(_stack));

   // Pop callee's parameters.

   __ ld(parameter_count, in_bytes(Method::const_offset()), R19_method);

   __ lhz(parameter_count, in_bytes(ConstMethod::size_of_parameters_offset()), parameter_count);

   __ sldi(parameter_count, parameter_count, Interpreter::logStackElementSize);

   __ add(R17_tos, R17_tos, parameter_count);

   // Result stub address array index

   // TODO: PPC port: assert(4 == methodOopDesc::sz_result_index(), "unexpected field size");

   __ lwa(result_index, method_(result_index));

   __ li(msg, BytecodeInterpreter::method_resume);

   //

   // Registers alive

   //   R16_thread

   //   R14_state    - address of caller's BytecodeInterpreter.

   //   R17_tos      - address of caller's tos with outgoing args already popped

   //   R3_RET       - integer return value, if any.

   //   F1_RET       - float return value, if any.

   //   result_index - index of result handler.

   //   msg          - message for resuming interpreter.

   //

   // Registers updated

   //   R3_RET       - new address of caller's tos, including result, if any

   //

   __ BIND(return_from_native_common);

   // Check for pending exception

   __ ld(pending_exception, thread_(pending_exception));

   __ cmpdi(CCR0, pending_exception, 0);

   __ beq(CCR0, return_from_native_no_exception);

   // If there's a pending exception, we really have no result, so

   // R3_RET is dead. Resume_interpreter assumes the new tos is in

   // R3_RET.

   __ mr(R3_RET, R17_tos);

   // `resume_interpreter' expects R15_prev_state to be alive.

   __ ld(R15_prev_state, state_(_prev_link));

   __ b(resume_interpreter);

   __ BIND(return_from_native_no_exception);

   // No pending exception, copy method result from native ABI register

   // to tos.

   // Address of stub descriptor address array.

   __ load_const(stub_addr, CppInterpreter::tosca_result_to_stack());

   // Pass address of tos to stub.

   __ mr(R4_ARG2, R17_tos);

   // Address of stub descriptor address.

   __ sldi(result_index, result_index, LogBytesPerWord);

   __ add(stub_addr, stub_addr, result_index);

   // Stub descriptor address.

   __ ld(stub_addr, 0, stub_addr);

   // TODO: don't do this via a call, do it in place!

   //

   // call stub via descriptor

   // in R3_ARG1/F1_ARG1: result value (R3_RET or F1_RET)

   __ call_stub(stub_addr);

   // new tos = result of call in R3_RET

   // `resume_interpreter' expects R15_prev_state to be alive.

   __ ld(R15_prev_state, state_(_prev_link));

   __ b(resume_interpreter);

   //=============================================================================

   // We encountered an exception while computing the interpreter

   // state, so R14_state isn't valid. Act as if we just returned from

   // the callee method with a pending exception.

   __ BIND(stack_overflow_return);

   //

   // Registers alive

   //   R16_thread        - JavaThread*

   //   R1_SP             - old stack pointer

   //   R19_method        - callee's Method

   //   R17_tos           - address of caller's tos (prepushed)

   //   R15_prev_state    - address of caller's BytecodeInterpreter or 0

   //   R18_locals        - address of callee's locals array

   //

   // Registers updated

   //   R3_RET           - address of resuming tos, if recursive unwind

   Label Lskip_unextend_SP;

   {

   const ConditionRegister is_initial_call = CCR0;

   const Register tos_save = R21_tmp1;

   const Register tmp = R22_tmp2;

   assert(tos_save->is_nonvolatile(), "need a nonvolatile");

   // Is the exception thrown in the initial Java frame of this frame

   // manager frame?

   __ cmpdi(is_initial_call, R15_prev_state, 0);

   __ bne(is_initial_call, Lskip_unextend_SP);

   // Pop any c2i extension from the stack. This is necessary in the

   // non-recursive case (that is we were called by the c2i adapter,

   // meaning we have to prev state). In this case we entered the frame

   // manager through a special entry which pushes the orignal

   // unextended SP to the stack. Here we load it back.

   __ ld(R0, _top_ijava_frame_abi(frame_manager_lr), R1_SP);

   __ mtlr(R0);

   // Resize frame to get rid of a potential extension.

   __ resize_frame_to_initial_caller(R11_scratch1, R12_scratch2);

   // Fall through

   __ bind(Lskip_unextend_SP);

   // Throw the exception via RuntimeStub "throw_StackOverflowError_entry".

   //

   // Previously, we called C-Code directly. As a consequence, a

   // possible GC tried to process the argument oops of the top frame

   // (see RegisterMap::clear, which sets the corresponding flag to

   // true). This lead to crashes because:

   // 1. The top register map did not contain locations for the argument registers

   // 2. The arguments are dead anyway, could be already overwritten in the worst case

   // Solution: Call via special runtime stub that pushes it's own frame. This runtime stub has the flag

   // "CodeBlob::caller_must_gc_arguments()" set to "false", what prevents the dead arguments getting GC'd.

   //

   // 2 cases exist:

   // 1. We were called by the c2i adapter / call stub

   // 2. We were called by the frame manager

   //

   // Both cases are handled by this code:

   // 1. - initial_caller_sp was saved on stack => Load it back and we're ok

   //    - control flow will be:

   //      throw_stackoverflow_stub->VM->throw_stackoverflow_stub->forward_excep->excp_blob of calling method

   // 2. - control flow will be:

   //      throw_stackoverflow_stub->VM->throw_stackoverflow_stub->forward_excep->

   //        ->rethrow_excp_entry of frame manager->resume_method

   //      Since we restored the caller SP above, the rethrow_excp_entry can restore the original interpreter state

   //      registers using the stack and resume the calling method with a pending excp.

   __ load_const(R3_ARG1, (StubRoutines::throw_StackOverflowError_entry()));

   __ mtctr(R3_ARG1);

   __ bctr();

   }

   //=============================================================================

   // We have popped a frame from an interpreted call. We are assured

   // of returning to an interpreted call by the popframe abi. We have

   // no return value all we have to do is pop the current frame and

   // then make sure that the top of stack (of the caller) gets set to

   // where it was when we entered the callee (i.e. the args are still

   // in place).  Or we are returning to the interpreter. In the first

   // case we must extract result (if any) from the java expression

   // stack and store it in the location the native abi would expect

   // for a call returning this type. In the second case we must simply

   // do a stack to stack move as we unwind.

   __ BIND(popping_frame);

   // Registers alive

   //   R14_state

   //   R15_prev_state

   //   R17_tos

   //

   // Registers updated

   //   R19_method

   //   R3_RET

   //   msg

   {

     Label L;

     // Reload callee method, gc may have moved it.

     __ ld(R19_method, state_(_method));

     // We may be returning to a deoptimized frame in which case the

     // usual assumption of a recursive return is not true.

     // not equal = is recursive call

     __ cmpdi(CCR0, R15_prev_state, 0);

     __ bne(CCR0, L);

     // Pop_frame capability.

     // The pop_frame api says that the underlying frame is a Java frame, in this case

     // (prev_state==null) it must be a compiled frame:

     //

     // Stack at this point: I, C2I + C, ...

     //

     // The outgoing arguments of the call have just been copied (popframe_preserve_args).

     // By the pop_frame api, we must end up in an interpreted frame. So the compiled frame

     // will be deoptimized. Deoptimization will restore the outgoing arguments from

     // popframe_preserve_args, adjust the tos such that it includes the popframe_preserve_args,

     // and adjust the bci such that the call will be executed again.

     // We have no results, just pop the interpreter frame, resize the compiled frame to get rid

     // of the c2i extension and return to the deopt_handler.

     __ b(unwind_initial_activation);

     // is recursive call

     __ bind(L);

     // Resume_interpreter expects the original tos in R3_RET.

     __ ld(R3_RET, prev_state_(_stack));

     // We're done.

     __ li(msg, BytecodeInterpreter::popping_frame);

     __ b(unwind_recursive_activation);

   }

   //=============================================================================

   // We have finished an interpreted call. We are either returning to

   // native (call_stub/c2) or we are returning to the interpreter.

   // When returning to native, we must extract the result (if any)

   // from the java expression stack and store it in the location the

   // native abi expects. When returning to the interpreter we must

   // simply do a stack to stack move as we unwind.

   __ BIND(return_from_interpreted_method);

   //

   // Registers alive

   //   R16_thread     - JavaThread*

   //   R15_prev_state - address of caller's BytecodeInterpreter or 0

   //   R14_state      - address of callee's interpreter state

   //   R1_SP          - callee's stack pointer

   //

   // Registers updated

   //   R19_method     - callee's method

   //   R3_RET         - address of result (new caller's tos),

   //

   // if returning to interpreted

   //   msg  - message for interpreter,

   // if returning to interpreted

   //

   // Check if this is the initial invocation of the frame manager.

   // If so, R15_prev_state will be null.

   __ cmpdi(CCR0, R15_prev_state, 0);

   // Reload callee method, gc may have moved it.

   __ ld(R19_method, state_(_method));

   // Load the method's result type.

   __ lwz(result_index, method_(result_index));

   // Go to return_to_initial_caller if R15_prev_state is null.

   __ beq(CCR0, return_to_initial_caller);

   // Copy callee's result to caller's expression stack via inline stack-to-stack

   // converters.

   {

     Register new_tos   = R3_RET;

     Register from_temp = R4_ARG2;

     Register from      = R5_ARG3;

     Register tos       = R6_ARG4;

     Register tmp1      = R7_ARG5;

     Register tmp2      = R8_ARG6;

     ConditionRegister result_type_is_void   = CCR1;

     ConditionRegister result_type_is_long   = CCR2;

     ConditionRegister result_type_is_double = CCR3;

     Label stack_to_stack_void;

     Label stack_to_stack_double_slot; // T_LONG, T_DOUBLE

     Label stack_to_stack_single_slot; // T_BOOLEAN, T_BYTE, T_CHAR, T_SHORT, T_INT, T_FLOAT, T_OBJECT

     Label stack_to_stack_done;

     // Pass callee's address of tos + BytesPerWord

     __ ld(from_temp, state_(_stack));

     // result type: void

     __ cmpwi(result_type_is_void, result_index, AbstractInterpreter::BasicType_as_index(T_VOID));

     // Pass caller's tos == callee's locals address

     __ ld(tos, state_(_locals));

     // result type: long

     __ cmpwi(result_type_is_long, result_index, AbstractInterpreter::BasicType_as_index(T_LONG));

     __ addi(from, from_temp, Interpreter::stackElementSize);

     // !! don't branch above this line !!

     // handle void

     __ beq(result_type_is_void,   stack_to_stack_void);

     // result type: double

     __ cmpwi(result_type_is_double, result_index, AbstractInterpreter::BasicType_as_index(T_DOUBLE));

     // handle long or double

     __ beq(result_type_is_long, stack_to_stack_double_slot);

     __ beq(result_type_is_double, stack_to_stack_double_slot);

     // fall through to single slot types (incl. object)

     {

       __ BIND(stack_to_stack_single_slot);

       // T_BOOLEAN, T_BYTE, T_CHAR, T_SHORT, T_INT, T_FLOAT, T_OBJECT

       __ ld(tmp1, 0, from);

       __ std(tmp1, 0, tos);

       // New expression stack top

       __ addi(new_tos, tos, - BytesPerWord);

       __ b(stack_to_stack_done);

     }

     {

       __ BIND(stack_to_stack_double_slot);

       // T_LONG, T_DOUBLE

       // Move both entries for debug purposes even though only one is live

       __ ld(tmp1, BytesPerWord, from);

       __ ld(tmp2, 0, from);

       __ std(tmp1, 0, tos);

       __ std(tmp2, -BytesPerWord, tos);

       // new expression stack top

       __ addi(new_tos, tos, - 2 * BytesPerWord); // two slots

       __ b(stack_to_stack_done);

     }

     {

       __ BIND(stack_to_stack_void);

       // T_VOID

       // new expression stack top

       __ mr(new_tos, tos);

       // fall through to stack_to_stack_done

     }

     __ BIND(stack_to_stack_done);

   }

   // new tos = R3_RET

   // Get the message for the interpreter

   __ li(msg, BytecodeInterpreter::method_resume);

   // And fall thru

   //=============================================================================

   // Restore caller's interpreter state and pass pointer to caller's

   // new tos to caller.

   __ BIND(unwind_recursive_activation);

   //

   // Registers alive

   //   R15_prev_state   - address of caller's BytecodeInterpreter

   //   R3_RET           - address of caller's tos

   //   msg              - message for caller's BytecodeInterpreter

   //   R1_SP            - callee's stack pointer

   //

   // Registers updated

   //   R14_state        - address of caller's BytecodeInterpreter

   //   R15_prev_state   - address of its parent or 0

   //

   // Pop callee's interpreter and set R14_state to caller's interpreter.

   __ pop_interpreter_state(/*prev_state_may_be_0=*/false);

   // And fall thru

   //=============================================================================

   // Resume the (calling) interpreter after a call.

   __ BIND(resume_interpreter);

   //

   // Registers alive

   //   R14_state        - address of resuming BytecodeInterpreter

   //   R15_prev_state   - address of its parent or 0

   //   R3_RET           - address of resuming tos

   //   msg              - message for resuming interpreter

   //   R1_SP            - callee's stack pointer

   //

   // Registers updated

   //   R1_SP            - caller's stack pointer

   //

   // Restore C stack pointer of caller (resuming interpreter),

   // R14_state already points to the resuming BytecodeInterpreter.

   __ pop_interpreter_frame_to_state(R14_state, R21_tmp1, R11_scratch1, R12_scratch2);

   // Store new address of tos (holding return value) in interpreter state.

   __ std(R3_RET, state_(_stack));

   // Store message for interpreter.

   __ stw(msg, state_(_msg));

   __ b(call_interpreter);

   //=============================================================================

   // Interpreter returning to native code (call_stub/c1/c2) from

   // initial activation. Convert stack result and unwind activation.

   __ BIND(return_to_initial_caller);

   //

   // Registers alive

   //   R19_method       - callee's Method

   //   R14_state        - address of callee's interpreter state

   //   R16_thread       - JavaThread

   //   R1_SP            - callee's stack pointer

   //

   // Registers updated

   //   R3_RET/F1_RET - result in expected output register

   //

   // If we have an exception pending we have no result and we

   // must figure out where to really return to.

   //

   __ ld(pending_exception, thread_(pending_exception));

   __ cmpdi(CCR0, pending_exception, 0);

   __ bne(CCR0, unwind_initial_activation_pending_exception);

   __ lwa(result_index, method_(result_index));

   // Address of stub descriptor address array.

   __ load_const(stub_addr, CppInterpreter::stack_result_to_native());

   // Pass address of callee's tos + BytesPerWord.

   // Will then point directly to result.

   __ ld(R3_ARG1, state_(_stack));

   __ addi(R3_ARG1, R3_ARG1, Interpreter::stackElementSize);

   // Address of stub descriptor address

   __ sldi(result_index, result_index, LogBytesPerWord);

   __ add(stub_addr, stub_addr, result_index);

   // Stub descriptor address

   __ ld(stub_addr, 0, stub_addr);

   // TODO: don't do this via a call, do it in place!

   //

   // call stub via descriptor

   __ call_stub(stub_addr);

   __ BIND(unwind_initial_activation);

   // Unwind from initial activation. No exception is pending.

   //

   // Stack layout at this point:

   //

   //    0       [TOP_IJAVA_FRAME_ABI]         <-- R1_SP

   //            ...

   //    CALLER  [PARENT_IJAVA_FRAME_ABI]

   //            ...

   //    CALLER  [unextended ABI]

   //            ...

   //

   //  The CALLER frame has a C2I adapter or is an entry-frame.

   //

   // An interpreter frame exists, we may pop the TOP_IJAVA_FRAME and

   // turn the caller's PARENT_IJAVA_FRAME back into a TOP_IJAVA_FRAME.

   // But, we simply restore the return pc from the caller's frame and

   // use the caller's initial_caller_sp as the new SP which pops the

   // interpreter frame and "resizes" the caller's frame to its "unextended"

   // size.

   // get rid of top frame

   __ pop_frame();

   // Load return PC from parent frame.

   __ ld(R21_tmp1, _parent_ijava_frame_abi(lr), R1_SP);

   // Resize frame to get rid of a potential extension.

   __ resize_frame_to_initial_caller(R11_scratch1, R12_scratch2);

   // update LR

   __ mtlr(R21_tmp1);

   // return

   __ blr();

   //=============================================================================

   // Unwind from initial activation. An exception is pending

   __ BIND(unwind_initial_activation_pending_exception);

   //

   // Stack layout at this point:

   //

   //   0       [TOP_IJAVA_FRAME_ABI]         <-- R1_SP

   //           ...

   //   CALLER  [PARENT_IJAVA_FRAME_ABI]

   //           ...

   //   CALLER  [unextended ABI]

   //           ...

   //

   // The CALLER frame has a C2I adapter or is an entry-frame.

   //

   // An interpreter frame exists, we may pop the TOP_IJAVA_FRAME and

   // turn the caller's PARENT_IJAVA_FRAME back into a TOP_IJAVA_FRAME.

   // But, we just pop the current TOP_IJAVA_FRAME and fall through

   __ pop_frame();

   __ ld(R3_ARG1, _top_ijava_frame_abi(lr), R1_SP);

   //

   // Stack layout at this point:

   //

   //   CALLER  [PARENT_IJAVA_FRAME_ABI]      <-- R1_SP

   //           ...

   //   CALLER  [unextended ABI]

   //           ...

   //

   // The CALLER frame has a C2I adapter or is an entry-frame.

   //

   // Registers alive

   //   R16_thread

   //   R3_ARG1 - return address to caller

   //

   // Registers updated

   //   R3_ARG1 - address of pending exception

   //   R4_ARG2 - issuing pc = return address to caller

   //   LR      - address of exception handler stub

   //

   // Resize frame to get rid of a potential extension.

   __ resize_frame_to_initial_caller(R11_scratch1, R12_scratch2);

   __ mr(R14, R3_ARG1);   // R14 := ARG1

   __ mr(R4_ARG2, R3_ARG1);  // ARG2 := ARG1

   // Find the address of the "catch_exception" stub.

   __ push_frame_abi112(0, R11_scratch1);

   __ call_VM_leaf(CAST_FROM_FN_PTR(address, SharedRuntime::exception_handler_for_return_address),

                   R16_thread,

                   R4_ARG2);

   __ pop_frame();

   // Load continuation address into LR.

   __ mtlr(R3_RET);

   // Load address of pending exception and clear it in thread object.

   __ ld(R3_ARG1/*R3_RET*/, thread_(pending_exception));

   __ li(R4_ARG2, 0);

   __ std(R4_ARG2, thread_(pending_exception));

   // re-load issuing pc

   __ mr(R4_ARG2, R14);

   // Branch to found exception handler.

   __ blr();

   //=============================================================================

   // Call a new method. Compute new args and trim the expression stack

   // to only what we are currently using and then recurse.

   __ BIND(call_method);

   //

   //  Registers alive

   //    R16_thread

   //    R14_state      - address of caller's BytecodeInterpreter

   //    R1_SP          - caller's stack pointer

   //

   //  Registers updated

   //    R15_prev_state - address of caller's BytecodeInterpreter

   //    R17_tos        - address of caller's tos

   //    R19_method     - callee's Method

   //    R1_SP          - trimmed back

   //

   // Very-local scratch registers.

   const Register offset = R21_tmp1;

   const Register tmp    = R22_tmp2;

   const Register self_entry  = R23_tmp3;

   const Register stub_entry  = R24_tmp4;

   const ConditionRegister cr = CCR0;

   // Load the address of the frame manager.

   __ load_const(self_entry, &interpreter_frame_manager);

   __ ld(self_entry, 0, self_entry);

   // Load BytecodeInterpreter._result._to_call._callee (callee's Method).

   __ ld(R19_method, state_(_result._to_call._callee));

   // Load BytecodeInterpreter._stack (outgoing tos).

   __ ld(R17_tos, state_(_stack));

   // Save address of caller's BytecodeInterpreter.

   __ mr(R15_prev_state, R14_state);

   // Load the callee's entry point.

   // Load BytecodeInterpreter._result._to_call._callee_entry_point.

   __ ld(stub_entry, state_(_result._to_call._callee_entry_point));

   // Check whether stub_entry is equal to self_entry.

   __ cmpd(cr, self_entry, stub_entry);

   // if (self_entry == stub_entry)

   //   do a re-dispatch

   __ beq(cr, re_dispatch);

   // else

   //   call the specialized entry (adapter for jni or compiled code)

   __ BIND(call_special);

   //

   // Call the entry generated by `InterpreterGenerator::generate_native_entry'.

   //

   // Registers alive

   //   R16_thread

   //   R15_prev_state    - address of caller's BytecodeInterpreter

   //   R19_method        - callee's Method

   //   R17_tos           - address of caller's tos

   //   R1_SP             - caller's stack pointer

   //

   // Mark return from specialized entry for generate_native_entry.

   guarantee(return_from_native_pc != (address) NULL, "precondition");

   frame_manager_specialized_return = return_from_native_pc;

   // Set sender_SP in case we call interpreter native wrapper which

   // will expect it. Compiled code should not care.

   __ mr(R21_sender_SP, R1_SP);

   // Do a tail call here, and let the link register point to

   // frame_manager_specialized_return which is return_from_native_pc.

   __ load_const(tmp, frame_manager_specialized_return);

   __ call_stub_and_return_to(stub_entry,  tmp /* return_pc=tmp */);