Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * 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/interpreter.hpp"

 #include "interpreter/interpreterGenerator.hpp"

 #include "interpreter/interpreterRuntime.hpp"

 #include "interpreter/templateTable.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 "prims/methodHandles.hpp"

 #include "runtime/arguments.hpp"

 #include "runtime/deoptimization.hpp"

 #include "runtime/frame.inline.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 COMPILER1

 #include "c1/c1_Runtime1.hpp"

 #endif

 #ifndef CC_INTERP

 #error "CC_INTERP must be defined on PPC"

 #endif

 #define __ _masm->

 #ifdef PRODUCT

 #define BLOCK_COMMENT(str) // nothing

 #else

 #define BLOCK_COMMENT(str) __ block_comment(str)

 #endif

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

 int AbstractInterpreter::BasicType_as_index(BasicType type) {

   int i = 0;

   switch (type) {

     case T_BOOLEAN: i = 0; break;

     case T_CHAR   : i = 1; break;

     case T_BYTE   : i = 2; break;

     case T_SHORT  : i = 3; break;

     case T_INT    : i = 4; break;

     case T_LONG   : i = 5; break;

     case T_VOID   : i = 6; break;

     case T_FLOAT  : i = 7; break;

     case T_DOUBLE : i = 8; break;

     case T_OBJECT : i = 9; break;

     case T_ARRAY  : i = 9; break;

     default       : ShouldNotReachHere();

   }

   assert(0 <= i && i < AbstractInterpreter::number_of_result_handlers, "index out of bounds");

   return i;

 }

 address AbstractInterpreterGenerator::generate_slow_signature_handler() {

   // Slow_signature handler that respects the PPC C calling conventions.

   //

   // We get called by the native entry code with our output register

   // area == 8. First we call InterpreterRuntime::get_result_handler

   // to copy the pointer to the signature string temporarily to the

   // first C-argument and to return the result_handler in

   // R3_RET. Since native_entry will copy the jni-pointer to the

   // first C-argument slot later on, it is OK to occupy this slot

   // temporarilly. Then we copy the argument list on the java

   // expression stack into native varargs format on the native stack

   // and load arguments into argument registers. Integer arguments in

   // the varargs vector will be sign-extended to 8 bytes.

   //

   // On entry:

   //   R3_ARG1        - intptr_t*     Address of java argument list in memory.

   //   R15_prev_state - BytecodeInterpreter* Address of interpreter state for

   //     this method

   //   R19_method

   //

   // On exit (just before return instruction):

   //   R3_RET            - contains the address of the result_handler.

   //   R4_ARG2           - is not updated for static methods and contains "this" otherwise.

   //   R5_ARG3-R10_ARG8: - When the (i-2)th Java argument is not of type float or double,

   //                       ARGi contains this argument. Otherwise, ARGi is not updated.

   //   F1_ARG1-F13_ARG13 - contain the first 13 arguments of type float or double.

   const int LogSizeOfTwoInstructions = 3;

   // FIXME: use Argument:: GL: Argument names different numbers!

   const int max_fp_register_arguments  = 13;

   const int max_int_register_arguments = 6;  // first 2 are reserved

   const Register arg_java       = R21_tmp1;

   const Register arg_c          = R22_tmp2;

   const Register signature      = R23_tmp3;  // is string

   const Register sig_byte       = R24_tmp4;

   const Register fpcnt          = R25_tmp5;

   const Register argcnt         = R26_tmp6;

   const Register intSlot        = R27_tmp7;

   const Register target_sp      = R28_tmp8;

   const FloatRegister floatSlot = F0;

   address entry = __ emit_fd();

   __ save_LR_CR(R0);

   __ save_nonvolatile_gprs(R1_SP, _spill_nonvolatiles_neg(r14));

   // We use target_sp for storing arguments in the C frame.

   __ mr(target_sp, R1_SP);

   __ push_frame_abi112_nonvolatiles(0, R11_scratch1);

   __ mr(arg_java, R3_ARG1);

   __ call_VM_leaf(CAST_FROM_FN_PTR(address, InterpreterRuntime::get_signature), R16_thread, R19_method);

   // Signature is in R3_RET. Signature is callee saved.

   __ mr(signature, R3_RET);

   // Reload method, it may have moved.

 #ifdef CC_INTERP

   __ ld(R19_method, state_(_method));

 #else

   __ unimplemented("slow signature handler 1");

 #endif

   // Get the result handler.

   __ call_VM_leaf(CAST_FROM_FN_PTR(address, InterpreterRuntime::get_result_handler), R16_thread, R19_method);

   // Reload method, it may have moved.

 #ifdef CC_INTERP

   __ ld(R19_method, state_(_method));

 #else

   __ unimplemented("slow signature handler 2");

 #endif

   {

     Label L;

     // test if static

     // _access_flags._flags must be at offset 0.

     // TODO PPC port: requires change in shared code.

     //assert(in_bytes(AccessFlags::flags_offset()) == 0,

     //       "MethodOopDesc._access_flags == MethodOopDesc._access_flags._flags");

     // _access_flags must be a 32 bit value.

     assert(sizeof(AccessFlags) == 4, "wrong size");

     __ lwa(R11_scratch1/*access_flags*/, method_(access_flags));

     // testbit with condition register.

     __ testbitdi(CCR0, R0, R11_scratch1/*access_flags*/, JVM_ACC_STATIC_BIT);

     __ btrue(CCR0, L);

     // For non-static functions, pass "this" in R4_ARG2 and copy it

     // to 2nd C-arg slot.

     // We need to box the Java object here, so we use arg_java

     // (address of current Java stack slot) as argument and don't

     // dereference it as in case of ints, floats, etc.

     __ mr(R4_ARG2, arg_java);

     __ addi(arg_java, arg_java, -BytesPerWord);

     __ std(R4_ARG2, _abi(carg_2), target_sp);

     __ bind(L);

   }

   // Will be incremented directly after loop_start. argcnt=0

   // corresponds to 3rd C argument.

   __ li(argcnt, -1);

   // arg_c points to 3rd C argument

   __ addi(arg_c, target_sp, _abi(carg_3));

   // no floating-point args parsed so far

   __ li(fpcnt, 0);

   Label move_intSlot_to_ARG, move_floatSlot_to_FARG;

   Label loop_start, loop_end;

   Label do_int, do_long, do_float, do_double, do_dontreachhere, do_object, do_array, do_boxed;

   // signature points to '(' at entry

 #ifdef ASSERT

   __ lbz(sig_byte, 0, signature);

   __ cmplwi(CCR0, sig_byte, '(');

   __ bne(CCR0, do_dontreachhere);

 #endif

   __ bind(loop_start);

   __ addi(argcnt, argcnt, 1);

   __ lbzu(sig_byte, 1, signature);

   __ cmplwi(CCR0, sig_byte, ')'); // end of signature

   __ beq(CCR0, loop_end);

   __ cmplwi(CCR0, sig_byte, 'B'); // byte

   __ beq(CCR0, do_int);

   __ cmplwi(CCR0, sig_byte, 'C'); // char

   __ beq(CCR0, do_int);

   __ cmplwi(CCR0, sig_byte, 'D'); // double

   __ beq(CCR0, do_double);

   __ cmplwi(CCR0, sig_byte, 'F'); // float

   __ beq(CCR0, do_float);

   __ cmplwi(CCR0, sig_byte, 'I'); // int

   __ beq(CCR0, do_int);

   __ cmplwi(CCR0, sig_byte, 'J'); // long

   __ beq(CCR0, do_long);

   __ cmplwi(CCR0, sig_byte, 'S'); // short

   __ beq(CCR0, do_int);

   __ cmplwi(CCR0, sig_byte, 'Z'); // boolean

   __ beq(CCR0, do_int);

   __ cmplwi(CCR0, sig_byte, 'L'); // object

   __ beq(CCR0, do_object);

   __ cmplwi(CCR0, sig_byte, '['); // array

   __ beq(CCR0, do_array);

   //  __ cmplwi(CCR0, sig_byte, 'V'); // void cannot appear since we do not parse the return type

   //  __ beq(CCR0, do_void);

   __ bind(do_dontreachhere);

   __ unimplemented("ShouldNotReachHere in slow_signature_handler", 120);

   __ bind(do_array);

   {

     Label start_skip, end_skip;

     __ bind(start_skip);

     __ lbzu(sig_byte, 1, signature);

     __ cmplwi(CCR0, sig_byte, '[');

     __ beq(CCR0, start_skip); // skip further brackets

     __ cmplwi(CCR0, sig_byte, '9');

     __ bgt(CCR0, end_skip);   // no optional size

     __ cmplwi(CCR0, sig_byte, '0');

     __ bge(CCR0, start_skip); // skip optional size

     __ bind(end_skip);

     __ cmplwi(CCR0, sig_byte, 'L');

     __ beq(CCR0, do_object);  // for arrays of objects, the name of the object must be skipped

     __ b(do_boxed);          // otherwise, go directly to do_boxed

   }

   __ bind(do_object);

   {

     Label L;

     __ bind(L);

     __ lbzu(sig_byte, 1, signature);

     __ cmplwi(CCR0, sig_byte, ';');

     __ bne(CCR0, L);

    }

   // Need to box the Java object here, so we use arg_java (address of

   // current Java stack slot) as argument and don't dereference it as

   // in case of ints, floats, etc.

   Label do_null;

   __ bind(do_boxed);

   __ ld(R0,0, arg_java);

   __ cmpdi(CCR0, R0, 0);

   __ li(intSlot,0);

   __ beq(CCR0, do_null);

   __ mr(intSlot, arg_java);

   __ bind(do_null);

   __ std(intSlot, 0, arg_c);

   __ addi(arg_java, arg_java, -BytesPerWord);

   __ addi(arg_c, arg_c, BytesPerWord);

   __ cmplwi(CCR0, argcnt, max_int_register_arguments);

   __ blt(CCR0, move_intSlot_to_ARG);

   __ b(loop_start);

   __ bind(do_int);

   __ lwa(intSlot, 0, arg_java);

   __ std(intSlot, 0, arg_c);

   __ addi(arg_java, arg_java, -BytesPerWord);

   __ addi(arg_c, arg_c, BytesPerWord);

   __ cmplwi(CCR0, argcnt, max_int_register_arguments);

   __ blt(CCR0, move_intSlot_to_ARG);

   __ b(loop_start);

   __ bind(do_long);

   __ ld(intSlot, -BytesPerWord, arg_java);

   __ std(intSlot, 0, arg_c);

   __ addi(arg_java, arg_java, - 2 * BytesPerWord);

   __ addi(arg_c, arg_c, BytesPerWord);

   __ cmplwi(CCR0, argcnt, max_int_register_arguments);

   __ blt(CCR0, move_intSlot_to_ARG);

   __ b(loop_start);

   __ bind(do_float);

   __ lfs(floatSlot, 0, arg_java);

 #if defined(LINUX)

   __ stfs(floatSlot, 4, arg_c);

 #elif defined(AIX)

   __ stfs(floatSlot, 0, arg_c);

 #else

 #error "unknown OS"

 #endif

   __ addi(arg_java, arg_java, -BytesPerWord);

   __ addi(arg_c, arg_c, BytesPerWord);

   __ cmplwi(CCR0, fpcnt, max_fp_register_arguments);

   __ blt(CCR0, move_floatSlot_to_FARG);

   __ b(loop_start);

   __ bind(do_double);

   __ lfd(floatSlot, - BytesPerWord, arg_java);

   __ stfd(floatSlot, 0, arg_c);

   __ addi(arg_java, arg_java, - 2 * BytesPerWord);

   __ addi(arg_c, arg_c, BytesPerWord);

   __ cmplwi(CCR0, fpcnt, max_fp_register_arguments);

   __ blt(CCR0, move_floatSlot_to_FARG);

   __ b(loop_start);

   __ bind(loop_end);

   __ pop_frame();

   __ restore_nonvolatile_gprs(R1_SP, _spill_nonvolatiles_neg(r14));

   __ restore_LR_CR(R0);

   __ blr();

   Label move_int_arg, move_float_arg;

   __ bind(move_int_arg); // each case must consist of 2 instructions (otherwise adapt LogSizeOfTwoInstructions)

   __ mr(R5_ARG3, intSlot);  __ b(loop_start);

   __ mr(R6_ARG4, intSlot);  __ b(loop_start);

   __ mr(R7_ARG5, intSlot);  __ b(loop_start);

   __ mr(R8_ARG6, intSlot);  __ b(loop_start);

   __ mr(R9_ARG7, intSlot);  __ b(loop_start);

   __ mr(R10_ARG8, intSlot); __ b(loop_start);

   __ bind(move_float_arg); // each case must consist of 2 instructions (otherwise adapt LogSizeOfTwoInstructions)

   __ fmr(F1_ARG1, floatSlot);   __ b(loop_start);

   __ fmr(F2_ARG2, floatSlot);   __ b(loop_start);

   __ fmr(F3_ARG3, floatSlot);   __ b(loop_start);

   __ fmr(F4_ARG4, floatSlot);   __ b(loop_start);

   __ fmr(F5_ARG5, floatSlot);   __ b(loop_start);

   __ fmr(F6_ARG6, floatSlot);   __ b(loop_start);

   __ fmr(F7_ARG7, floatSlot);   __ b(loop_start);

   __ fmr(F8_ARG8, floatSlot);   __ b(loop_start);

   __ fmr(F9_ARG9, floatSlot);   __ b(loop_start);

   __ fmr(F10_ARG10, floatSlot); __ b(loop_start);

   __ fmr(F11_ARG11, floatSlot); __ b(loop_start);

   __ fmr(F12_ARG12, floatSlot); __ b(loop_start);

   __ fmr(F13_ARG13, floatSlot); __ b(loop_start);

   __ bind(move_intSlot_to_ARG);

   __ sldi(R0, argcnt, LogSizeOfTwoInstructions);

   __ load_const(R11_scratch1, move_int_arg); // Label must be bound here.

   __ add(R11_scratch1, R0, R11_scratch1);

   __ mtctr(R11_scratch1/*branch_target*/);

   __ bctr();

   __ bind(move_floatSlot_to_FARG);

   __ sldi(R0, fpcnt, LogSizeOfTwoInstructions);

   __ addi(fpcnt, fpcnt, 1);

   __ load_const(R11_scratch1, move_float_arg); // Label must be bound here.

   __ add(R11_scratch1, R0, R11_scratch1);

   __ mtctr(R11_scratch1/*branch_target*/);

   __ bctr();

   return entry;

 }

 address AbstractInterpreterGenerator::generate_result_handler_for(BasicType type) {

   //

   // Registers alive

   //   R3_RET

   //   LR

   //

   // Registers updated

   //   R3_RET

   //

   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);

     __ b(done);

     __ bind(is_false);

     __ li(R3_RET, 0);

     break;

   case T_BYTE:

      // sign extend 8 bits

      __ extsb(R3_RET, R3_RET);

      break;

   case T_CHAR:

      // zero extend 16 bits

      __ clrldi(R3_RET, R3_RET, 48);

      break;

   case T_SHORT:

      // sign extend 16 bits

      __ extsh(R3_RET, R3_RET);

      break;

   case T_INT:

      // sign extend 32 bits

      __ extsw(R3_RET, R3_RET);

      break;

   case T_LONG:

      break;

   case T_OBJECT:

     // unbox result if not null

     __ cmpdi(CCR0, R3_RET, 0);

     __ beq(CCR0, done);

     __ ld(R3_RET, 0, R3_RET);

     __ verify_oop(R3_RET);

     break;

   case T_FLOAT:

      break;

   case T_DOUBLE:

      break;

   case T_VOID:

      break;

   default: ShouldNotReachHere();

   }

   __ BIND(done);

   __ blr();

   return entry;

 }

 // Abstract method entry.

 //

 address InterpreterGenerator::generate_abstract_entry(void) {

   address entry = __ pc();

   //

   // Registers alive

   //   R16_thread     - JavaThread*

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

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

   //   LR             - return address to caller

   //

   // Stack layout at this point:

   //

   //   0       [TOP_IJAVA_FRAME_ABI]         <-- R1_SP

   //           alignment (optional)

   //           [outgoing Java arguments]

   //           ...

   //   PARENT  [PARENT_IJAVA_FRAME_ABI]

   //            ...

   //

   // Can't use call_VM here because we have not set up a new

   // interpreter state. Make the call to the vm and make it look like

   // our caller set up the JavaFrameAnchor.

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

   // Push a new C frame and save LR.

   __ save_LR_CR(R0);

   __ push_frame_abi112_nonvolatiles(0, R11_scratch1);

   // This is not a leaf but we have a JavaFrameAnchor now and we will

   // check (create) exceptions afterward so this is ok.

   __ call_VM_leaf(CAST_FROM_FN_PTR(address, InterpreterRuntime::throw_AbstractMethodError));

   // Pop the C frame and restore LR.

   __ pop_frame();

   __ restore_LR_CR(R0);

   // Reset JavaFrameAnchor from call_VM_leaf above.

   __ reset_last_Java_frame();

   // Return to frame manager, it will handle the pending exception.

   __ blr();

   return entry;

 }

 // Call an accessor method (assuming it is resolved, otherwise drop into

 // vanilla (slow path) entry.

 address InterpreterGenerator::generate_accessor_entry(void) {

   if(!UseFastAccessorMethods && (!FLAG_IS_ERGO(UseFastAccessorMethods)))

     return NULL;

   Label Ldone, Lslow_path;

   const Register Rthis = R3_ARG1,

          Rconst_method = R4_ARG2,

          Rcodes        = Rconst_method,

          Rcpool_cache  = R5_ARG3,

          Rscratch      = R11_scratch1,

          Rjvmti_mode   = Rscratch,

          Roffset       = R12_scratch2,

          Rflags        = R6_ARG4;

   address entry = __ pc();

   // Check for safepoint:

   // Ditch this, real man don't need safepoint checks.

   // Also check for JVMTI mode

   // Check for null obj, take slow path if so.

 #ifdef CC_INTERP

   __ ld(Rthis, Interpreter::stackElementSize, R17_tos);

 #else

   Unimplemented()

 #endif

   __ lwz(Rjvmti_mode, thread_(interp_only_mode));

   __ cmpdi(CCR1, Rthis, 0);

   __ cmpwi(CCR0, Rjvmti_mode, 0);

   __ crorc(/*CCR0 eq*/2, /*CCR1 eq*/4+2, /*CCR0 eq*/2);

   __ beq(CCR0, Lslow_path); // this==null or jvmti_mode!=0

   // Do 2 things in parallel:

   // 1. Load the index out of the first instruction word, which looks like this:

   //    <0x2a><0xb4><index (2 byte, native endianess)>.

   // 2. Load constant pool cache base.

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

   __ ld(Rcpool_cache, in_bytes(ConstMethod::constants_offset()), Rconst_method);

   __ lhz(Rcodes, in_bytes(ConstMethod::codes_offset()) + 2, Rconst_method); // Lower half of 32 bit field.

   __ ld(Rcpool_cache, ConstantPool::cache_offset_in_bytes(), Rcpool_cache);

   // Get the const pool entry by means of <index>.

   const int codes_shift = exact_log2(in_words(ConstantPoolCacheEntry::size()) * BytesPerWord);

   __ slwi(Rscratch, Rcodes, codes_shift); // (codes&0xFFFF)<<codes_shift

   __ add(Rcpool_cache, Rscratch, Rcpool_cache);

   // Check if cpool cache entry is resolved.

   // We are resolved if the indices offset contains the current bytecode.

   ByteSize cp_base_offset = ConstantPoolCache::base_offset();

   // Big Endian:

   __ lbz(Rscratch, in_bytes(cp_base_offset) + in_bytes(ConstantPoolCacheEntry::indices_offset()) + 7 - 2, Rcpool_cache);

   __ cmpwi(CCR0, Rscratch, Bytecodes::_getfield);

   __ bne(CCR0, Lslow_path);

   __ isync(); // Order succeeding loads wrt. load of _indices field from cpool_cache.

   // Finally, start loading the value: Get cp cache entry into regs.

   __ ld(Rflags, in_bytes(cp_base_offset) + in_bytes(ConstantPoolCacheEntry::flags_offset()), Rcpool_cache);

   __ ld(Roffset, in_bytes(cp_base_offset) + in_bytes(ConstantPoolCacheEntry::f2_offset()), Rcpool_cache);

   // Get field type.

   // (Rflags>>ConstantPoolCacheEntry::tos_state_shift)&((1<<ConstantPoolCacheEntry::tos_state_bits)-1)

   __ rldicl(Rflags, Rflags, 64-ConstantPoolCacheEntry::tos_state_shift, 64-ConstantPoolCacheEntry::tos_state_bits);

 #ifdef ASSERT

     __ ld(R9_ARG7, 0, R1_SP);

     __ ld(R10_ARG8, 0, R21_sender_SP);

     __ cmpd(CCR0, R9_ARG7, R10_ARG8);

     __ asm_assert_eq("backlink", 0x543);

 #endif // ASSERT

   __ mr(R1_SP, R21_sender_SP); // Cut the stack back to where the caller started.

   // Load the return value according to field type.

   Label Litos, Lltos, Lbtos, Lctos, Lstos;

   __ cmpdi(CCR1, Rflags, itos);

   __ cmpdi(CCR0, Rflags, ltos);

   __ beq(CCR1, Litos);

   __ beq(CCR0, Lltos);

   __ cmpdi(CCR1, Rflags, btos);

   __ cmpdi(CCR0, Rflags, ctos);

   __ beq(CCR1, Lbtos);

   __ beq(CCR0, Lctos);

   __ cmpdi(CCR1, Rflags, stos);

   __ beq(CCR1, Lstos);

 #ifdef ASSERT

   __ cmpdi(CCR0, Rflags, atos);

   __ asm_assert_eq("what type is this?", 0x432);

 #endif

   // fallthru: __ bind(Latos);

   __ load_heap_oop(R3_RET, (RegisterOrConstant)Roffset, Rthis);

   __ blr();

   __ bind(Litos);

   __ lwax(R3_RET, Rthis, Roffset);

   __ blr();

   __ bind(Lltos);

   __ ldx(R3_RET, Rthis, Roffset);

   __ blr();

   __ bind(Lbtos);

   __ lbzx(R3_RET, Rthis, Roffset);

   __ extsb(R3_RET, R3_RET);

   __ blr();

   __ bind(Lctos);

   __ lhzx(R3_RET, Rthis, Roffset);

   __ blr();

   __ bind(Lstos);

   __ lhax(R3_RET, Rthis, Roffset);

   __ blr();

   __ bind(Lslow_path);

   assert(Interpreter::entry_for_kind(Interpreter::zerolocals), "Normal entry must have been generated by now");

   __ load_const_optimized(Rscratch, Interpreter::entry_for_kind(Interpreter::zerolocals), R0);

   __ mtctr(Rscratch);

   __ bctr();

   __ flush();

   return entry;

 }

 // Interpreter intrinsic for WeakReference.get().

 // 1. Don't push a full blown frame and go on dispatching, but fetch the value

 //    into R8 and return quickly

 // 2. If G1 is active we *must* execute this intrinsic for corrrectness:

 //    It contains a GC barrier which puts the reference into the satb buffer

 //    to indicate that someone holds a strong reference to the object the

 //    weak ref points to!

 address InterpreterGenerator::generate_Reference_get_entry(void) {

   // Code: _aload_0, _getfield, _areturn

   // parameter size = 1

   //

   // The code that gets generated by this routine is split into 2 parts:

   //    1. the "intrinsified" code for G1 (or any SATB based GC),

   //    2. the slow path - which is an expansion of the regular method entry.

   //

   // Notes:

   // * In the G1 code we do not check whether we need to block for

   //   a safepoint. If G1 is enabled then we must execute the specialized

   //   code for Reference.get (except when the Reference object is null)

   //   so that we can log the value in the referent field with an SATB

   //   update buffer.

   //   If the code for the getfield template is modified so that the

   //   G1 pre-barrier code is executed when the current method is

   //   Reference.get() then going through the normal method entry

   //   will be fine.

   // * The G1 code can, however, check the receiver object (the instance

   //   of java.lang.Reference) and jump to the slow path if null. If the

   //   Reference object is null then we obviously cannot fetch the referent

   //   and so we don't need to call the G1 pre-barrier. Thus we can use the

   //   regular method entry code to generate the NPE.

   //

   // This code is based on generate_accessor_enty.

   address entry = __ pc();

   const int referent_offset = java_lang_ref_Reference::referent_offset;

   guarantee(referent_offset > 0, "referent offset not initialized");

   if (UseG1GC) {

      Label slow_path;

     // Debugging not possible, so can't use __ skip_if_jvmti_mode(slow_path, GR31_SCRATCH);

     // In the G1 code we don't check if we need to reach a safepoint. We

     // continue and the thread will safepoint at the next bytecode dispatch.

     // If the receiver is null then it is OK to jump to the slow path.

 #ifdef CC_INTERP

      __ ld(R3_RET, Interpreter::stackElementSize, R17_tos); // get receiver

 #else

      Unimplemented();

 #endif

     // Check if receiver == NULL and go the slow path.

     __ cmpdi(CCR0, R3_RET, 0);

     __ beq(CCR0, slow_path);

     // Load the value of the referent field.

     __ load_heap_oop_not_null(R3_RET, referent_offset, R3_RET);

     // Generate the G1 pre-barrier code to log the value of

     // the referent field in an SATB buffer. Note with

     // these parameters the pre-barrier does not generate

     // the load of the previous value.

     // Restore caller sp for c2i case.

 #ifdef ASSERT

       __ ld(R9_ARG7, 0, R1_SP);

       __ ld(R10_ARG8, 0, R21_sender_SP);

       __ cmpd(CCR0, R9_ARG7, R10_ARG8);

       __ asm_assert_eq("backlink", 0x544);

 #endif // ASSERT

     __ mr(R1_SP, R21_sender_SP); // Cut the stack back to where the caller started.

     __ g1_write_barrier_pre(noreg,         // obj

                             noreg,         // offset

                             R3_RET,        // pre_val

                             R11_scratch1,  // tmp

                             R12_scratch2,  // tmp

                             true);         // needs_frame

     __ blr();

     // Generate regular method entry.

     __ bind(slow_path);

     assert(Interpreter::entry_for_kind(Interpreter::zerolocals), "Normal entry must have been generated by now");

     __ load_const_optimized(R11_scratch1, Interpreter::entry_for_kind(Interpreter::zerolocals), R0);

     __ mtctr(R11_scratch1);

     __ bctr();

     __ flush();

     return entry;

   } else {

     return generate_accessor_entry();

   }

 }

 void Deoptimization::unwind_callee_save_values(frame* f, vframeArray* vframe_array) {

   // This code is sort of the equivalent of C2IAdapter::setup_stack_frame back in

   // the days we had adapter frames. When we deoptimize a situation where a

   // compiled caller calls a compiled caller will have registers it expects

   // to survive the call to the callee. If we deoptimize the callee the only

   // way we can restore these registers is to have the oldest interpreter

   // frame that we create restore these values. That is what this routine

   // will accomplish.

   // At the moment we have modified c2 to not have any callee save registers

   // so this problem does not exist and this routine is just a place holder.

   assert(f->is_interpreted_frame(), "must be interpreted");

 }