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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

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  */

 #include "precompiled.hpp"

 #include "asm/assembler.hpp"

 #include "asm/assembler.inline.hpp"

 #include "asm/macroAssembler.inline.hpp"

 #include "compiler/disassembler.hpp"

 #include "gc_interface/collectedHeap.inline.hpp"

 #include "interpreter/interpreter.hpp"

 #include "memory/cardTableModRefBS.hpp"

 #include "memory/resourceArea.hpp"

 #include "prims/methodHandles.hpp"

 #include "runtime/biasedLocking.hpp"

 #include "runtime/interfaceSupport.hpp"

 #include "runtime/objectMonitor.hpp"

 #include "runtime/os.hpp"

 #include "runtime/sharedRuntime.hpp"

 #include "runtime/stubRoutines.hpp"

 #include "utilities/macros.hpp"

 #if INCLUDE_ALL_GCS

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"

 #include "gc_implementation/g1/heapRegion.hpp"

 #endif // INCLUDE_ALL_GCS

 #ifdef PRODUCT

 #define BLOCK_COMMENT(str) // nothing

 #else

 #define BLOCK_COMMENT(str) block_comment(str)

 #endif

 #ifdef ASSERT

 // On RISC, there's no benefit to verifying instruction boundaries.

 bool AbstractAssembler::pd_check_instruction_mark() { return false; }

 #endif

 void MacroAssembler::ld_largeoffset_unchecked(Register d, int si31, Register a, int emit_filler_nop) {

   assert(Assembler::is_simm(si31, 31) && si31 >= 0, "si31 out of range");

   if (Assembler::is_simm(si31, 16)) {

     ld(d, si31, a);

     if (emit_filler_nop) nop();

   } else {

     const int hi = MacroAssembler::largeoffset_si16_si16_hi(si31);

     const int lo = MacroAssembler::largeoffset_si16_si16_lo(si31);

     addis(d, a, hi);

     ld(d, lo, d);

   }

 }

 void MacroAssembler::ld_largeoffset(Register d, int si31, Register a, int emit_filler_nop) {

   assert_different_registers(d, a);

   ld_largeoffset_unchecked(d, si31, a, emit_filler_nop);

 }

 void MacroAssembler::load_sized_value(Register dst, RegisterOrConstant offs, Register base,

                                       size_t size_in_bytes, bool is_signed) {

   switch (size_in_bytes) {

   case  8:              ld(dst, offs, base);                         break;

   case  4:  is_signed ? lwa(dst, offs, base) : lwz(dst, offs, base); break;

   case  2:  is_signed ? lha(dst, offs, base) : lhz(dst, offs, base); break;

   case  1:  lbz(dst, offs, base); if (is_signed) extsb(dst, dst);    break; // lba doesn't exist :(

   default:  ShouldNotReachHere();

   }

 }

 void MacroAssembler::store_sized_value(Register dst, RegisterOrConstant offs, Register base,

                                        size_t size_in_bytes) {

   switch (size_in_bytes) {

   case  8:  std(dst, offs, base); break;

   case  4:  stw(dst, offs, base); break;

   case  2:  sth(dst, offs, base); break;

   case  1:  stb(dst, offs, base); break;

   default:  ShouldNotReachHere();

   }

 }

 void MacroAssembler::align(int modulus) {

   while (offset() % modulus != 0) nop();

 }

 // Issue instructions that calculate given TOC from global TOC.

 void MacroAssembler::calculate_address_from_global_toc(Register dst, address addr, bool hi16, bool lo16,

                                                        bool add_relocation, bool emit_dummy_addr) {

   int offset = -1;

   if (emit_dummy_addr) {

     offset = -128; // dummy address

   } else if (addr != (address)(intptr_t)-1) {

     offset = MacroAssembler::offset_to_global_toc(addr);

   }

   if (hi16) {

     addis(dst, R29, MacroAssembler::largeoffset_si16_si16_hi(offset));

   }

   if (lo16) {

     if (add_relocation) {

       // Relocate at the addi to avoid confusion with a load from the method's TOC.

       relocate(internal_word_Relocation::spec(addr));

     }

     addi(dst, dst, MacroAssembler::largeoffset_si16_si16_lo(offset));

   }

 }

 int MacroAssembler::patch_calculate_address_from_global_toc_at(address a, address bound, address addr) {

   const int offset = MacroAssembler::offset_to_global_toc(addr);

   const address inst2_addr = a;

   const int inst2 = *(int *)inst2_addr;

   // The relocation points to the second instruction, the addi,

   // and the addi reads and writes the same register dst.

   const int dst = inv_rt_field(inst2);

   assert(is_addi(inst2) && inv_ra_field(inst2) == dst, "must be addi reading and writing dst");

   // Now, find the preceding addis which writes to dst.

   int inst1 = 0;

   address inst1_addr = inst2_addr - BytesPerInstWord;

   while (inst1_addr >= bound) {

     inst1 = *(int *) inst1_addr;

     if (is_addis(inst1) && inv_rt_field(inst1) == dst) {

       // Stop, found the addis which writes dst.

       break;

     }

     inst1_addr -= BytesPerInstWord;

   }

   assert(is_addis(inst1) && inv_ra_field(inst1) == 29 /* R29 */, "source must be global TOC");

   set_imm((int *)inst1_addr, MacroAssembler::largeoffset_si16_si16_hi(offset));

   set_imm((int *)inst2_addr, MacroAssembler::largeoffset_si16_si16_lo(offset));

   return (int)((intptr_t)addr - (intptr_t)inst1_addr);

 }

 address MacroAssembler::get_address_of_calculate_address_from_global_toc_at(address a, address bound) {

   const address inst2_addr = a;

   const int inst2 = *(int *)inst2_addr;

   // The relocation points to the second instruction, the addi,

   // and the addi reads and writes the same register dst.

   const int dst = inv_rt_field(inst2);

   assert(is_addi(inst2) && inv_ra_field(inst2) == dst, "must be addi reading and writing dst");

   // Now, find the preceding addis which writes to dst.

   int inst1 = 0;

   address inst1_addr = inst2_addr - BytesPerInstWord;

   while (inst1_addr >= bound) {

     inst1 = *(int *) inst1_addr;

     if (is_addis(inst1) && inv_rt_field(inst1) == dst) {

       // stop, found the addis which writes dst

       break;

     }

     inst1_addr -= BytesPerInstWord;

   }

   assert(is_addis(inst1) && inv_ra_field(inst1) == 29 /* R29 */, "source must be global TOC");

   int offset = (get_imm(inst1_addr, 0) << 16) + get_imm(inst2_addr, 0);

   // -1 is a special case

   if (offset == -1) {

     return (address)(intptr_t)-1;

   } else {

     return global_toc() + offset;

   }

 }

 #ifdef _LP64

 // Patch compressed oops or klass constants.

 int MacroAssembler::patch_set_narrow_oop(address a, address bound, narrowOop data) {

   assert(UseCompressedOops, "Should only patch compressed oops");

   const address inst2_addr = a;

   const int inst2 = *(int *)inst2_addr;

   // The relocation points to the second instruction, the addi,

   // and the addi reads and writes the same register dst.

   const int dst = inv_rt_field(inst2);

   assert(is_addi(inst2) && inv_ra_field(inst2) == dst, "must be addi reading and writing dst");

   // Now, find the preceding addis which writes to dst.

   int inst1 = 0;

   address inst1_addr = inst2_addr - BytesPerInstWord;

   bool inst1_found = false;

   while (inst1_addr >= bound) {

     inst1 = *(int *)inst1_addr;

     if (is_lis(inst1) && inv_rs_field(inst1) == dst) { inst1_found = true; break; }

     inst1_addr -= BytesPerInstWord;

   }

   assert(inst1_found, "inst is not lis");

   int xc = (data >> 16) & 0xffff;

   int xd = (data >>  0) & 0xffff;

   set_imm((int *)inst1_addr,((short)(xc + ((xd & 0x8000) != 0 ? 1 : 0)))); // see enc_load_con_narrow1/2

   set_imm((int *)inst2_addr, (short)(xd));

   return (int)((intptr_t)inst2_addr - (intptr_t)inst1_addr);

 }

 // Get compressed oop or klass constant.

 narrowOop MacroAssembler::get_narrow_oop(address a, address bound) {

   assert(UseCompressedOops, "Should only patch compressed oops");

   const address inst2_addr = a;

   const int inst2 = *(int *)inst2_addr;

   // The relocation points to the second instruction, the addi,

   // and the addi reads and writes the same register dst.

   const int dst = inv_rt_field(inst2);

   assert(is_addi(inst2) && inv_ra_field(inst2) == dst, "must be addi reading and writing dst");

   // Now, find the preceding lis which writes to dst.

   int inst1 = 0;

   address inst1_addr = inst2_addr - BytesPerInstWord;

   bool inst1_found = false;

   while (inst1_addr >= bound) {

     inst1 = *(int *) inst1_addr;

     if (is_lis(inst1) && inv_rs_field(inst1) == dst) { inst1_found = true; break;}

     inst1_addr -= BytesPerInstWord;

   }

   assert(inst1_found, "inst is not lis");

   uint xl = ((unsigned int) (get_imm(inst2_addr,0) & 0xffff));

   uint xh = (((((xl & 0x8000) != 0 ? -1 : 0) + get_imm(inst1_addr,0)) & 0xffff) << 16);

   return (int) (xl | xh);

 }

 #endif // _LP64

 void MacroAssembler::load_const_from_method_toc(Register dst, AddressLiteral& a, Register toc) {

   int toc_offset = 0;

   // Use RelocationHolder::none for the constant pool entry, otherwise

   // we will end up with a failing NativeCall::verify(x) where x is

   // the address of the constant pool entry.

   // FIXME: We should insert relocation information for oops at the constant

   // pool entries instead of inserting it at the loads; patching of a constant

   // pool entry should be less expensive.

   Unimplemented();

   if (false) {

     address oop_address = address_constant((address)a.value(), RelocationHolder::none);

     // Relocate at the pc of the load.

     relocate(a.rspec());

     toc_offset = (int)(oop_address - code()->consts()->start());

   }

   ld_largeoffset_unchecked(dst, toc_offset, toc, true);

 }

 bool MacroAssembler::is_load_const_from_method_toc_at(address a) {

   const address inst1_addr = a;

   const int inst1 = *(int *)inst1_addr;

    // The relocation points to the ld or the addis.

    return (is_ld(inst1)) ||

           (is_addis(inst1) && inv_ra_field(inst1) != 0);

 }

 int MacroAssembler::get_offset_of_load_const_from_method_toc_at(address a) {

   assert(is_load_const_from_method_toc_at(a), "must be load_const_from_method_toc");

   const address inst1_addr = a;

   const int inst1 = *(int *)inst1_addr;

   if (is_ld(inst1)) {

     return inv_d1_field(inst1);

   } else if (is_addis(inst1)) {

     const int dst = inv_rt_field(inst1);

     // Now, find the succeeding ld which reads and writes to dst.

     address inst2_addr = inst1_addr + BytesPerInstWord;

     int inst2 = 0;

     while (true) {

       inst2 = *(int *) inst2_addr;

       if (is_ld(inst2) && inv_ra_field(inst2) == dst && inv_rt_field(inst2) == dst) {

         // Stop, found the ld which reads and writes dst.

         break;

       }

       inst2_addr += BytesPerInstWord;

     }

     return (inv_d1_field(inst1) << 16) + inv_d1_field(inst2);

   }

   ShouldNotReachHere();

   return 0;

 }

 // Get the constant from a `load_const' sequence.

 long MacroAssembler::get_const(address a) {

   assert(is_load_const_at(a), "not a load of a constant");

   const int *p = (const int*) a;

   unsigned long x = (((unsigned long) (get_imm(a,0) & 0xffff)) << 48);

   if (is_ori(*(p+1))) {

     x |= (((unsigned long) (get_imm(a,1) & 0xffff)) << 32);

     x |= (((unsigned long) (get_imm(a,3) & 0xffff)) << 16);

     x |= (((unsigned long) (get_imm(a,4) & 0xffff)));

   } else if (is_lis(*(p+1))) {

     x |= (((unsigned long) (get_imm(a,2) & 0xffff)) << 32);

     x |= (((unsigned long) (get_imm(a,1) & 0xffff)) << 16);

     x |= (((unsigned long) (get_imm(a,3) & 0xffff)));

   } else {

     ShouldNotReachHere();

     return (long) 0;

   }

   return (long) x;

 }

 // Patch the 64 bit constant of a `load_const' sequence. This is a low

 // level procedure. It neither flushes the instruction cache nor is it

 // mt safe.

 void MacroAssembler::patch_const(address a, long x) {

   assert(is_load_const_at(a), "not a load of a constant");

   int *p = (int*) a;

   if (is_ori(*(p+1))) {

     set_imm(0 + p, (x >> 48) & 0xffff);

     set_imm(1 + p, (x >> 32) & 0xffff);

     set_imm(3 + p, (x >> 16) & 0xffff);

     set_imm(4 + p, x & 0xffff);

   } else if (is_lis(*(p+1))) {

     set_imm(0 + p, (x >> 48) & 0xffff);

     set_imm(2 + p, (x >> 32) & 0xffff);

     set_imm(1 + p, (x >> 16) & 0xffff);

     set_imm(3 + p, x & 0xffff);

   } else {

     ShouldNotReachHere();

   }

 }

 AddressLiteral MacroAssembler::allocate_metadata_address(Metadata* obj) {

   assert(oop_recorder() != NULL, "this assembler needs a Recorder");

   int index = oop_recorder()->allocate_metadata_index(obj);

   RelocationHolder rspec = metadata_Relocation::spec(index);

   return AddressLiteral((address)obj, rspec);

 }

 AddressLiteral MacroAssembler::constant_metadata_address(Metadata* obj) {

   assert(oop_recorder() != NULL, "this assembler needs a Recorder");

   int index = oop_recorder()->find_index(obj);

   RelocationHolder rspec = metadata_Relocation::spec(index);

   return AddressLiteral((address)obj, rspec);

 }

 AddressLiteral MacroAssembler::allocate_oop_address(jobject obj) {

   assert(oop_recorder() != NULL, "this assembler needs an OopRecorder");

   int oop_index = oop_recorder()->allocate_oop_index(obj);

   return AddressLiteral(address(obj), oop_Relocation::spec(oop_index));

 }

 AddressLiteral MacroAssembler::constant_oop_address(jobject obj) {

   assert(oop_recorder() != NULL, "this assembler needs an OopRecorder");

   int oop_index = oop_recorder()->find_index(obj);

   return AddressLiteral(address(obj), oop_Relocation::spec(oop_index));

 }

 RegisterOrConstant MacroAssembler::delayed_value_impl(intptr_t* delayed_value_addr,

                                                       Register tmp, int offset) {

   intptr_t value = *delayed_value_addr;

   if (value != 0) {

     return RegisterOrConstant(value + offset);

   }

   // Load indirectly to solve generation ordering problem.

   // static address, no relocation

   int simm16_offset = load_const_optimized(tmp, delayed_value_addr, noreg, true);

   ld(tmp, simm16_offset, tmp); // must be aligned ((xa & 3) == 0)

   if (offset != 0) {

     addi(tmp, tmp, offset);

   }

   return RegisterOrConstant(tmp);

 }

 #ifndef PRODUCT

 void MacroAssembler::pd_print_patched_instruction(address branch) {

   Unimplemented(); // TODO: PPC port

 }

 #endif // ndef PRODUCT

 // Conditional far branch for destinations encodable in 24+2 bits.

 void MacroAssembler::bc_far(int boint, int biint, Label& dest, int optimize) {

   // If requested by flag optimize, relocate the bc_far as a

   // runtime_call and prepare for optimizing it when the code gets

   // relocated.

   if (optimize == bc_far_optimize_on_relocate) {

     relocate(relocInfo::runtime_call_type);

   }

   // variant 2:

   //

   //    b!cxx SKIP

   //    bxx   DEST

   //  SKIP:

   //

   const int opposite_boint = add_bhint_to_boint(opposite_bhint(inv_boint_bhint(boint)),

                                                 opposite_bcond(inv_boint_bcond(boint)));

   // We emit two branches.

   // First, a conditional branch which jumps around the far branch.

   const address not_taken_pc = pc() + 2 * BytesPerInstWord;

   const address bc_pc        = pc();

   bc(opposite_boint, biint, not_taken_pc);

   const int bc_instr = *(int*)bc_pc;

   assert(not_taken_pc == (address)inv_bd_field(bc_instr, (intptr_t)bc_pc), "postcondition");

   assert(opposite_boint == inv_bo_field(bc_instr), "postcondition");

   assert(boint == add_bhint_to_boint(opposite_bhint(inv_boint_bhint(inv_bo_field(bc_instr))),

                                      opposite_bcond(inv_boint_bcond(inv_bo_field(bc_instr)))),

          "postcondition");

   assert(biint == inv_bi_field(bc_instr), "postcondition");

   // Second, an unconditional far branch which jumps to dest.

   // Note: target(dest) remembers the current pc (see CodeSection::target)

   //       and returns the current pc if the label is not bound yet; when

   //       the label gets bound, the unconditional far branch will be patched.

   const address target_pc = target(dest);

   const address b_pc  = pc();

   b(target_pc);

   assert(not_taken_pc == pc(),                     "postcondition");

   assert(dest.is_bound() || target_pc == b_pc, "postcondition");

 }

 bool MacroAssembler::is_bc_far_at(address instruction_addr) {

   return is_bc_far_variant1_at(instruction_addr) ||

          is_bc_far_variant2_at(instruction_addr) ||

          is_bc_far_variant3_at(instruction_addr);

 }

 address MacroAssembler::get_dest_of_bc_far_at(address instruction_addr) {

   if (is_bc_far_variant1_at(instruction_addr)) {

     const address instruction_1_addr = instruction_addr;

     const int instruction_1 = *(int*)instruction_1_addr;

     return (address)inv_bd_field(instruction_1, (intptr_t)instruction_1_addr);

   } else if (is_bc_far_variant2_at(instruction_addr)) {

     const address instruction_2_addr = instruction_addr + 4;

     return bxx_destination(instruction_2_addr);

   } else if (is_bc_far_variant3_at(instruction_addr)) {

     return instruction_addr + 8;

   }

   // variant 4 ???

   ShouldNotReachHere();

   return NULL;

 }

 void MacroAssembler::set_dest_of_bc_far_at(address instruction_addr, address dest) {

   if (is_bc_far_variant3_at(instruction_addr)) {

     // variant 3, far cond branch to the next instruction, already patched to nops:

     //

     //    nop

     //    endgroup

     //  SKIP/DEST:

     //

     return;

   }

   // first, extract boint and biint from the current branch

   int boint = 0;

   int biint = 0;

   ResourceMark rm;

   const int code_size = 2 * BytesPerInstWord;

   CodeBuffer buf(instruction_addr, code_size);

   MacroAssembler masm(&buf);

   if (is_bc_far_variant2_at(instruction_addr) && dest == instruction_addr + 8) {

     // Far branch to next instruction: Optimize it by patching nops (produce variant 3).

     masm.nop();

     masm.endgroup();

   } else {

     if (is_bc_far_variant1_at(instruction_addr)) {

       // variant 1, the 1st instruction contains the destination address:

       //

       //    bcxx  DEST

       //    endgroup

       //

       const int instruction_1 = *(int*)(instruction_addr);

       boint = inv_bo_field(instruction_1);

       biint = inv_bi_field(instruction_1);

     } else if (is_bc_far_variant2_at(instruction_addr)) {

       // variant 2, the 2nd instruction contains the destination address:

       //

       //    b!cxx SKIP

       //    bxx   DEST

       //  SKIP:

       //

       const int instruction_1 = *(int*)(instruction_addr);

       boint = add_bhint_to_boint(opposite_bhint(inv_boint_bhint(inv_bo_field(instruction_1))),

           opposite_bcond(inv_boint_bcond(inv_bo_field(instruction_1))));

       biint = inv_bi_field(instruction_1);

     } else {

       // variant 4???

       ShouldNotReachHere();

     }

     // second, set the new branch destination and optimize the code

     if (dest != instruction_addr + 4 && // the bc_far is still unbound!

         masm.is_within_range_of_bcxx(dest, instruction_addr)) {

       // variant 1:

       //

       //    bcxx  DEST

       //    endgroup

       //

       masm.bc(boint, biint, dest);

       masm.endgroup();

     } else {

       // variant 2:

       //

       //    b!cxx SKIP

       //    bxx   DEST

       //  SKIP:

       //

       const int opposite_boint = add_bhint_to_boint(opposite_bhint(inv_boint_bhint(boint)),

                                                     opposite_bcond(inv_boint_bcond(boint)));

       const address not_taken_pc = masm.pc() + 2 * BytesPerInstWord;

       masm.bc(opposite_boint, biint, not_taken_pc);

       masm.b(dest);

     }

   }

   ICache::invalidate_range(instruction_addr, code_size);

 }

 // Emit a NOT mt-safe patchable 64 bit absolute call/jump.

 void MacroAssembler::bxx64_patchable(address dest, relocInfo::relocType rt, bool link) {

   // get current pc

   uint64_t start_pc = (uint64_t) pc();

   const address pc_of_bl = (address) (start_pc + (6*BytesPerInstWord)); // bl is last

   const address pc_of_b  = (address) (start_pc + (0*BytesPerInstWord)); // b is first

   // relocate here

   if (rt != relocInfo::none) {

     relocate(rt);

   }

   if ( ReoptimizeCallSequences &&

        (( link && is_within_range_of_b(dest, pc_of_bl)) ||

         (!link && is_within_range_of_b(dest, pc_of_b)))) {

     // variant 2:

     // Emit an optimized, pc-relative call/jump.

     if (link) {

       // some padding

       nop();

       nop();

       nop();

       nop();

       nop();

       nop();

       // do the call

       assert(pc() == pc_of_bl, "just checking");

       bl(dest, relocInfo::none);

     } else {

       // do the jump

       assert(pc() == pc_of_b, "just checking");

       b(dest, relocInfo::none);

       // some padding

       nop();

       nop();

       nop();

       nop();

       nop();

       nop();

     }

     // Assert that we can identify the emitted call/jump.

     assert(is_bxx64_patchable_variant2_at((address)start_pc, link),

            "can't identify emitted call");

   } else {

     // variant 1:

     mr(R0, R11);  // spill R11 -> R0.

     // Load the destination address into CTR,

     // calculate destination relative to global toc.

     calculate_address_from_global_toc(R11, dest, true, true, false);

     mtctr(R11);

     mr(R11, R0);  // spill R11 <- R0.

     nop();

     // do the call/jump

     if (link) {

       bctrl();

     } else{

       bctr();

     }

     // Assert that we can identify the emitted call/jump.

     assert(is_bxx64_patchable_variant1b_at((address)start_pc, link),

            "can't identify emitted call");

   }

   // Assert that we can identify the emitted call/jump.

   assert(is_bxx64_patchable_at((address)start_pc, link),

          "can't identify emitted call");

   assert(get_dest_of_bxx64_patchable_at((address)start_pc, link) == dest,

          "wrong encoding of dest address");

 }

 // Identify a bxx64_patchable instruction.

 bool MacroAssembler::is_bxx64_patchable_at(address instruction_addr, bool link) {

   return is_bxx64_patchable_variant1b_at(instruction_addr, link)

     //|| is_bxx64_patchable_variant1_at(instruction_addr, link)

       || is_bxx64_patchable_variant2_at(instruction_addr, link);

 }

 // Does the call64_patchable instruction use a pc-relative encoding of

 // the call destination?

 bool MacroAssembler::is_bxx64_patchable_pcrelative_at(address instruction_addr, bool link) {

   // variant 2 is pc-relative

   return is_bxx64_patchable_variant2_at(instruction_addr, link);

 }

 // Identify variant 1.

 bool MacroAssembler::is_bxx64_patchable_variant1_at(address instruction_addr, bool link) {

   unsigned int* instr = (unsigned int*) instruction_addr;

   return (link ? is_bctrl(instr[6]) : is_bctr(instr[6])) // bctr[l]

       && is_mtctr(instr[5]) // mtctr

     && is_load_const_at(instruction_addr);

 }

 // Identify variant 1b: load destination relative to global toc.

 bool MacroAssembler::is_bxx64_patchable_variant1b_at(address instruction_addr, bool link) {

   unsigned int* instr = (unsigned int*) instruction_addr;

   return (link ? is_bctrl(instr[6]) : is_bctr(instr[6])) // bctr[l]

     && is_mtctr(instr[3]) // mtctr

     && is_calculate_address_from_global_toc_at(instruction_addr + 2*BytesPerInstWord, instruction_addr);

 }

 // Identify variant 2.

 bool MacroAssembler::is_bxx64_patchable_variant2_at(address instruction_addr, bool link) {

   unsigned int* instr = (unsigned int*) instruction_addr;

   if (link) {

     return is_bl (instr[6])  // bl dest is last

       && is_nop(instr[0])  // nop

       && is_nop(instr[1])  // nop

       && is_nop(instr[2])  // nop

       && is_nop(instr[3])  // nop

       && is_nop(instr[4])  // nop

       && is_nop(instr[5]); // nop

   } else {

     return is_b  (instr[0])  // b  dest is first

       && is_nop(instr[1])  // nop

       && is_nop(instr[2])  // nop

       && is_nop(instr[3])  // nop

       && is_nop(instr[4])  // nop

       && is_nop(instr[5])  // nop

       && is_nop(instr[6]); // nop

   }

 }

 // Set dest address of a bxx64_patchable instruction.

 void MacroAssembler::set_dest_of_bxx64_patchable_at(address instruction_addr, address dest, bool link) {

   ResourceMark rm;

   int code_size = MacroAssembler::bxx64_patchable_size;

   CodeBuffer buf(instruction_addr, code_size);

   MacroAssembler masm(&buf);

   masm.bxx64_patchable(dest, relocInfo::none, link);

   ICache::invalidate_range(instruction_addr, code_size);

 }

 // Get dest address of a bxx64_patchable instruction.

 address MacroAssembler::get_dest_of_bxx64_patchable_at(address instruction_addr, bool link) {

   if (is_bxx64_patchable_variant1_at(instruction_addr, link)) {

     return (address) (unsigned long) get_const(instruction_addr);

   } else if (is_bxx64_patchable_variant2_at(instruction_addr, link)) {

     unsigned int* instr = (unsigned int*) instruction_addr;

     if (link) {

       const int instr_idx = 6; // bl is last

       int branchoffset = branch_destination(instr[instr_idx], 0);

       return instruction_addr + branchoffset + instr_idx*BytesPerInstWord;

     } else {

       const int instr_idx = 0; // b is first

       int branchoffset = branch_destination(instr[instr_idx], 0);

       return instruction_addr + branchoffset + instr_idx*BytesPerInstWord;

     }

   // Load dest relative to global toc.

   } else if (is_bxx64_patchable_variant1b_at(instruction_addr, link)) {

     return get_address_of_calculate_address_from_global_toc_at(instruction_addr + 2*BytesPerInstWord,

                                                                instruction_addr);

   } else {

     ShouldNotReachHere();

     return NULL;

   }

 }

 // Uses ordering which corresponds to ABI:

 //    _savegpr0_14:  std  r14,-144(r1)

 //    _savegpr0_15:  std  r15,-136(r1)

 //    _savegpr0_16:  std  r16,-128(r1)

 void MacroAssembler::save_nonvolatile_gprs(Register dst, int offset) {

   std(R14, offset, dst);   offset += 8;

   std(R15, offset, dst);   offset += 8;

   std(R16, offset, dst);   offset += 8;

   std(R17, offset, dst);   offset += 8;

   std(R18, offset, dst);   offset += 8;

   std(R19, offset, dst);   offset += 8;

   std(R20, offset, dst);   offset += 8;

   std(R21, offset, dst);   offset += 8;

   std(R22, offset, dst);   offset += 8;

   std(R23, offset, dst);   offset += 8;

   std(R24, offset, dst);   offset += 8;

   std(R25, offset, dst);   offset += 8;

   std(R26, offset, dst);   offset += 8;

   std(R27, offset, dst);   offset += 8;

   std(R28, offset, dst);   offset += 8;

   std(R29, offset, dst);   offset += 8;

   std(R30, offset, dst);   offset += 8;

   std(R31, offset, dst);   offset += 8;

   stfd(F14, offset, dst);   offset += 8;

   stfd(F15, offset, dst);   offset += 8;

   stfd(F16, offset, dst);   offset += 8;

   stfd(F17, offset, dst);   offset += 8;

   stfd(F18, offset, dst);   offset += 8;

   stfd(F19, offset, dst);   offset += 8;

   stfd(F20, offset, dst);   offset += 8;

   stfd(F21, offset, dst);   offset += 8;

   stfd(F22, offset, dst);   offset += 8;

   stfd(F23, offset, dst);   offset += 8;

   stfd(F24, offset, dst);   offset += 8;

   stfd(F25, offset, dst);   offset += 8;

   stfd(F26, offset, dst);   offset += 8;

   stfd(F27, offset, dst);   offset += 8;

   stfd(F28, offset, dst);   offset += 8;

   stfd(F29, offset, dst);   offset += 8;

   stfd(F30, offset, dst);   offset += 8;

   stfd(F31, offset, dst);

 }

 // Uses ordering which corresponds to ABI:

 //    _restgpr0_14:  ld   r14,-144(r1)

 //    _restgpr0_15:  ld   r15,-136(r1)

 //    _restgpr0_16:  ld   r16,-128(r1)

 void MacroAssembler::restore_nonvolatile_gprs(Register src, int offset) {

   ld(R14, offset, src);   offset += 8;

   ld(R15, offset, src);   offset += 8;

   ld(R16, offset, src);   offset += 8;

   ld(R17, offset, src);   offset += 8;

   ld(R18, offset, src);   offset += 8;

   ld(R19, offset, src);   offset += 8;

   ld(R20, offset, src);   offset += 8;

   ld(R21, offset, src);   offset += 8;

   ld(R22, offset, src);   offset += 8;

   ld(R23, offset, src);   offset += 8;

   ld(R24, offset, src);   offset += 8;

   ld(R25, offset, src);   offset += 8;

   ld(R26, offset, src);   offset += 8;

   ld(R27, offset, src);   offset += 8;

   ld(R28, offset, src);   offset += 8;

   ld(R29, offset, src);   offset += 8;

   ld(R30, offset, src);   offset += 8;

   ld(R31, offset, src);   offset += 8;

   // FP registers

   lfd(F14, offset, src);   offset += 8;

   lfd(F15, offset, src);   offset += 8;

   lfd(F16, offset, src);   offset += 8;

   lfd(F17, offset, src);   offset += 8;

   lfd(F18, offset, src);   offset += 8;

   lfd(F19, offset, src);   offset += 8;

   lfd(F20, offset, src);   offset += 8;

   lfd(F21, offset, src);   offset += 8;

   lfd(F22, offset, src);   offset += 8;

   lfd(F23, offset, src);   offset += 8;

   lfd(F24, offset, src);   offset += 8;

   lfd(F25, offset, src);   offset += 8;

   lfd(F26, offset, src);   offset += 8;

   lfd(F27, offset, src);   offset += 8;

   lfd(F28, offset, src);   offset += 8;

   lfd(F29, offset, src);   offset += 8;

   lfd(F30, offset, src);   offset += 8;

   lfd(F31, offset, src);

 }

 // For verify_oops.

 void MacroAssembler::save_volatile_gprs(Register dst, int offset) {

   std(R3,  offset, dst);   offset += 8;

   std(R4,  offset, dst);   offset += 8;

   std(R5,  offset, dst);   offset += 8;

   std(R6,  offset, dst);   offset += 8;

   std(R7,  offset, dst);   offset += 8;

   std(R8,  offset, dst);   offset += 8;

   std(R9,  offset, dst);   offset += 8;

   std(R10, offset, dst);   offset += 8;

   std(R11, offset, dst);   offset += 8;

   std(R12, offset, dst);

 }

 // For verify_oops.

 void MacroAssembler::restore_volatile_gprs(Register src, int offset) {

   ld(R3,  offset, src);   offset += 8;

   ld(R4,  offset, src);   offset += 8;

   ld(R5,  offset, src);   offset += 8;

   ld(R6,  offset, src);   offset += 8;

   ld(R7,  offset, src);   offset += 8;

   ld(R8,  offset, src);   offset += 8;

   ld(R9,  offset, src);   offset += 8;

   ld(R10, offset, src);   offset += 8;

   ld(R11, offset, src);   offset += 8;

   ld(R12, offset, src);

 }

 void MacroAssembler::save_LR_CR(Register tmp) {

   mfcr(tmp);

   std(tmp, _abi(cr), R1_SP);

   mflr(tmp);

   std(tmp, _abi(lr), R1_SP);

   // Tmp must contain lr on exit! (see return_addr and prolog in ppc64.ad)

 }

 void MacroAssembler::restore_LR_CR(Register tmp) {

   assert(tmp != R1_SP, "must be distinct");

   ld(tmp, _abi(lr), R1_SP);

   mtlr(tmp);

   ld(tmp, _abi(cr), R1_SP);

   mtcr(tmp);

 }

 address MacroAssembler::get_PC_trash_LR(Register result) {

   Label L;

   bl(L);

   bind(L);

   address lr_pc = pc();

   mflr(result);

   return lr_pc;

 }

 void MacroAssembler::resize_frame(Register offset, Register tmp) {

 #ifdef ASSERT

   assert_different_registers(offset, tmp, R1_SP);

   andi_(tmp, offset, frame::alignment_in_bytes-1);

   asm_assert_eq("resize_frame: unaligned", 0x204);

 #endif

   // tmp <- *(SP)

   ld(tmp, _abi(callers_sp), R1_SP);

   // addr <- SP + offset;

   // *(addr) <- tmp;

   // SP <- addr

   stdux(tmp, R1_SP, offset);

 }

 void MacroAssembler::resize_frame(int offset, Register tmp) {

   assert(is_simm(offset, 16), "too big an offset");

   assert_different_registers(tmp, R1_SP);

   assert((offset & (frame::alignment_in_bytes-1))==0, "resize_frame: unaligned");

   // tmp <- *(SP)

   ld(tmp, _abi(callers_sp), R1_SP);

   // addr <- SP + offset;

   // *(addr) <- tmp;

   // SP <- addr

   stdu(tmp, offset, R1_SP);

 }

 void MacroAssembler::resize_frame_absolute(Register addr, Register tmp1, Register tmp2) {

   // (addr == tmp1) || (addr == tmp2) is allowed here!

   assert(tmp1 != tmp2, "must be distinct");

   // compute offset w.r.t. current stack pointer

   // tmp_1 <- addr - SP (!)

   subf(tmp1, R1_SP, addr);

   // atomically update SP keeping back link.

   resize_frame(tmp1/* offset */, tmp2/* tmp */);

 }

 void MacroAssembler::push_frame(Register bytes, Register tmp) {

 #ifdef ASSERT

   assert(bytes != R0, "r0 not allowed here");

   andi_(R0, bytes, frame::alignment_in_bytes-1);

   asm_assert_eq("push_frame(Reg, Reg): unaligned", 0x203);

 #endif

   neg(tmp, bytes);

   stdux(R1_SP, R1_SP, tmp);

 }

 // Push a frame of size `bytes'.

 void MacroAssembler::push_frame(unsigned int bytes, Register tmp) {

   long offset = align_addr(bytes, frame::alignment_in_bytes);

   if (is_simm(-offset, 16)) {

     stdu(R1_SP, -offset, R1_SP);

   } else {

     load_const(tmp, -offset);

     stdux(R1_SP, R1_SP, tmp);

   }

 }

 // Push a frame of size `bytes' plus abi112 on top.

 void MacroAssembler::push_frame_abi112(unsigned int bytes, Register tmp) {

   push_frame(bytes + frame::abi_112_size, tmp);

 }

 // Setup up a new C frame with a spill area for non-volatile GPRs and

 // additional space for local variables.

 void MacroAssembler::push_frame_abi112_nonvolatiles(unsigned int bytes,

                                                     Register tmp) {

   push_frame(bytes + frame::abi_112_size + frame::spill_nonvolatiles_size, tmp);

 }

 // Pop current C frame.

 void MacroAssembler::pop_frame() {

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

 }

 // Generic version of a call to C function via a function descriptor

 // with variable support for C calling conventions (TOC, ENV, etc.).

 // Updates and returns _last_calls_return_pc.

 address MacroAssembler::branch_to(Register function_descriptor, bool and_link, bool save_toc_before_call,

                                   bool restore_toc_after_call, bool load_toc_of_callee, bool load_env_of_callee) {

   // we emit standard ptrgl glue code here

   assert((function_descriptor != R0), "function_descriptor cannot be R0");

   // retrieve necessary entries from the function descriptor

   ld(R0, in_bytes(FunctionDescriptor::entry_offset()), function_descriptor);

   mtctr(R0);

   if (load_toc_of_callee) {

     ld(R2_TOC, in_bytes(FunctionDescriptor::toc_offset()), function_descriptor);

   }

   if (load_env_of_callee) {

     ld(R11, in_bytes(FunctionDescriptor::env_offset()), function_descriptor);

   } else if (load_toc_of_callee) {

     li(R11, 0);

   }

   // do a call or a branch

   if (and_link) {

     bctrl();

   } else {

     bctr();

   }

   _last_calls_return_pc = pc();

   return _last_calls_return_pc;

 }

 // Call a C function via a function descriptor and use full C calling

 // conventions.

 // We don't use the TOC in generated code, so there is no need to save

 // and restore its value.

 address MacroAssembler::call_c(Register fd) {

   return branch_to(fd, /*and_link=*/true,

                        /*save toc=*/false,

                        /*restore toc=*/false,

                        /*load toc=*/true,

                        /*load env=*/true);

 }

 address MacroAssembler::call_c(const FunctionDescriptor* fd, relocInfo::relocType rt) {

   if (rt != relocInfo::none) {

     // this call needs to be relocatable

     if (!ReoptimizeCallSequences

         || (rt != relocInfo::runtime_call_type && rt != relocInfo::none)

         || fd == NULL   // support code-size estimation

         || !fd->is_friend_function()

         || fd->entry() == NULL) {

       // it's not a friend function as defined by class FunctionDescriptor,

       // so do a full call-c here.

       load_const(R11, (address)fd, R0);

       bool has_env = (fd != NULL && fd->env() != NULL);

       return branch_to(R11, /*and_link=*/true,

                                 /*save toc=*/false,

                                 /*restore toc=*/false,

                                 /*load toc=*/true,

                                 /*load env=*/has_env);

     } else {

       // It's a friend function. Load the entry point and don't care about

       // toc and env. Use an optimizable call instruction, but ensure the

       // same code-size as in the case of a non-friend function.

       nop();

       nop();

       nop();

       bl64_patchable(fd->entry(), rt);

       _last_calls_return_pc = pc();

       return _last_calls_return_pc;

     }

   } else {

     // This call does not need to be relocatable, do more aggressive

     // optimizations.

     if (!ReoptimizeCallSequences

       || !fd->is_friend_function()) {

       // It's not a friend function as defined by class FunctionDescriptor,

       // so do a full call-c here.

       load_const(R11, (address)fd, R0);

       return branch_to(R11, /*and_link=*/true,

                                 /*save toc=*/false,

                                 /*restore toc=*/false,

                                 /*load toc=*/true,

                                 /*load env=*/true);

     } else {

       // it's a friend function, load the entry point and don't care about

       // toc and env.

       address dest = fd->entry();

       if (is_within_range_of_b(dest, pc())) {

         bl(dest);

       } else {

         bl64_patchable(dest, rt);

       }

       _last_calls_return_pc = pc();

       return _last_calls_return_pc;

     }

   }

 }

 // Call a C function.  All constants needed reside in TOC.

 //

 // Read the address to call from the TOC.

 // Read env from TOC, if fd specifies an env.

 // Read new TOC from TOC.

 address MacroAssembler::call_c_using_toc(const FunctionDescriptor* fd,

                                          relocInfo::relocType rt, Register toc) {

   if (!ReoptimizeCallSequences

     || (rt != relocInfo::runtime_call_type && rt != relocInfo::none)

     || !fd->is_friend_function()) {

     // It's not a friend function as defined by class FunctionDescriptor,

     // so do a full call-c here.

     assert(fd->entry() != NULL, "function must be linked");

     AddressLiteral fd_entry(fd->entry());

     load_const_from_method_toc(R11, fd_entry, toc);

     mtctr(R11);

     if (fd->env() == NULL) {

       li(R11, 0);

       nop();

     } else {

       AddressLiteral fd_env(fd->env());

       load_const_from_method_toc(R11, fd_env, toc);

     }

     AddressLiteral fd_toc(fd->toc());

     load_toc_from_toc(R2_TOC, fd_toc, toc);

     // R2_TOC is killed.

     bctrl();

     _last_calls_return_pc = pc();

   } else {

     // It's a friend function, load the entry point and don't care about

     // toc and env. Use an optimizable call instruction, but ensure the

     // same code-size as in the case of a non-friend function.

     nop();

     bl64_patchable(fd->entry(), rt);

     _last_calls_return_pc = pc();

   }

   return _last_calls_return_pc;

 }

 void MacroAssembler::call_VM_base(Register oop_result,

                                   Register last_java_sp,

                                   address  entry_point,

                                   bool     check_exceptions) {

   BLOCK_COMMENT("call_VM {");

   // Determine last_java_sp register.

   if (!last_java_sp->is_valid()) {

     last_java_sp = R1_SP;

   }

   set_top_ijava_frame_at_SP_as_last_Java_frame(last_java_sp, R11_scratch1);

   // ARG1 must hold thread address.

   mr(R3_ARG1, R16_thread);

   address return_pc = call_c((FunctionDescriptor*)entry_point, relocInfo::none);

   reset_last_Java_frame();

   // Check for pending exceptions.

   if (check_exceptions) {

     // We don't check for exceptions here.

     ShouldNotReachHere();

   }

   // Get oop result if there is one and reset the value in the thread.

   if (oop_result->is_valid()) {

     get_vm_result(oop_result);

   }

   _last_calls_return_pc = return_pc;

   BLOCK_COMMENT("} call_VM");

 }

 void MacroAssembler::call_VM_leaf_base(address entry_point) {

   BLOCK_COMMENT("call_VM_leaf {");

   call_c(CAST_FROM_FN_PTR(FunctionDescriptor*, entry_point), relocInfo::none);

   BLOCK_COMMENT("} call_VM_leaf");

 }

 void MacroAssembler::call_VM(Register oop_result, address entry_point, bool check_exceptions) {

   call_VM_base(oop_result, noreg, entry_point, check_exceptions);

 }

 void MacroAssembler::call_VM(Register oop_result, address entry_point, Register arg_1,

                              bool check_exceptions) {

   // R3_ARG1 is reserved for the thread.

   mr_if_needed(R4_ARG2, arg_1);

   call_VM(oop_result, entry_point, check_exceptions);

 }

 void MacroAssembler::call_VM(Register oop_result, address entry_point, Register arg_1, Register arg_2,

                              bool check_exceptions) {

   // R3_ARG1 is reserved for the thread

   mr_if_needed(R4_ARG2, arg_1);

   assert(arg_2 != R4_ARG2, "smashed argument");

   mr_if_needed(R5_ARG3, arg_2);

   call_VM(oop_result, entry_point, check_exceptions);

 }

 void MacroAssembler::call_VM_leaf(address entry_point) {

   call_VM_leaf_base(entry_point);

 }

 void MacroAssembler::call_VM_leaf(address entry_point, Register arg_1) {

   mr_if_needed(R3_ARG1, arg_1);

   call_VM_leaf(entry_point);

 }

 void MacroAssembler::call_VM_leaf(address entry_point, Register arg_1, Register arg_2) {

   mr_if_needed(R3_ARG1, arg_1);

   assert(arg_2 != R3_ARG1, "smashed argument");

   mr_if_needed(R4_ARG2, arg_2);

   call_VM_leaf(entry_point);

 }

 void MacroAssembler::call_VM_leaf(address entry_point, Register arg_1, Register arg_2, Register arg_3) {

   mr_if_needed(R3_ARG1, arg_1);

   assert(arg_2 != R3_ARG1, "smashed argument");

   mr_if_needed(R4_ARG2, arg_2);

   assert(arg_3 != R3_ARG1 && arg_3 != R4_ARG2, "smashed argument");

   mr_if_needed(R5_ARG3, arg_3);

   call_VM_leaf(entry_point);

 }

 // Check whether instruction is a read access to the polling page

 // which was emitted by load_from_polling_page(..).

 bool MacroAssembler::is_load_from_polling_page(int instruction, void* ucontext,

                                                address* polling_address_ptr) {

   if (!is_ld(instruction))

     return false; // It's not a ld. Fail.

   int rt = inv_rt_field(instruction);

   int ra = inv_ra_field(instruction);

   int ds = inv_ds_field(instruction);

   if (!(ds == 0 && ra != 0 && rt == 0)) {

     return false; // It's not a ld(r0, X, ra). Fail.

   }

   if (!ucontext) {

     // Set polling address.

     if (polling_address_ptr != NULL) {

       *polling_address_ptr = NULL;

     }

     return true; // No ucontext given. Can't check value of ra. Assume true.

   }

 #ifdef LINUX

   // Ucontext given. Check that register ra contains the address of

   // the safepoing polling page.

   ucontext_t* uc = (ucontext_t*) ucontext;

   // Set polling address.

   address addr = (address)uc->uc_mcontext.regs->gpr[ra] + (ssize_t)ds;

   if (polling_address_ptr != NULL) {

     *polling_address_ptr = addr;

   }

   return os::is_poll_address(addr);

 #else

   // Not on Linux, ucontext must be NULL.

   ShouldNotReachHere();

   return false;

 #endif

 }

 bool MacroAssembler::is_memory_serialization(int instruction, JavaThread* thread, void* ucontext) {

 #ifdef LINUX

   ucontext_t* uc = (ucontext_t*) ucontext;

   if (is_stwx(instruction) || is_stwux(instruction)) {

     int ra = inv_ra_field(instruction);

     int rb = inv_rb_field(instruction);

     // look up content of ra and rb in ucontext

     address ra_val=(address)uc->uc_mcontext.regs->gpr[ra];

     long rb_val=(long)uc->uc_mcontext.regs->gpr[rb];

     return os::is_memory_serialize_page(thread, ra_val+rb_val);

   } else if (is_stw(instruction) || is_stwu(instruction)) {

     int ra = inv_ra_field(instruction);

     int d1 = inv_d1_field(instruction);

     // look up content of ra in ucontext

     address ra_val=(address)uc->uc_mcontext.regs->gpr[ra];

     return os::is_memory_serialize_page(thread, ra_val+d1);

   } else {

     return false;

   }

 #else

   // workaround not needed on !LINUX :-)

   ShouldNotCallThis();

   return false;

 #endif

 }

 void MacroAssembler::bang_stack_with_offset(int offset) {

   // When increasing the stack, the old stack pointer will be written

   // to the new top of stack according to the PPC64 abi.

   // Therefore, stack banging is not necessary when increasing

   // the stack by <= os::vm_page_size() bytes.

   // When increasing the stack by a larger amount, this method is

   // called repeatedly to bang the intermediate pages.

   // Stack grows down, caller passes positive offset.

   assert(offset > 0, "must bang with positive offset");

   long stdoffset = -offset;

   if (is_simm(stdoffset, 16)) {

     // Signed 16 bit offset, a simple std is ok.

     if (UseLoadInstructionsForStackBangingPPC64) {

       ld(R0, (int)(signed short)stdoffset, R1_SP);

     } else {

       std(R0,(int)(signed short)stdoffset, R1_SP);

     }

   } else if (is_simm(stdoffset, 31)) {

     const int hi = MacroAssembler::largeoffset_si16_si16_hi(stdoffset);

     const int lo = MacroAssembler::largeoffset_si16_si16_lo(stdoffset);

     Register tmp = R11;

     addis(tmp, R1_SP, hi);

     if (UseLoadInstructionsForStackBangingPPC64) {

       ld(R0,  lo, tmp);

     } else {

       std(R0, lo, tmp);

     }

   } else {

     ShouldNotReachHere();

   }

 }

 // If instruction is a stack bang of the form

 //    std    R0,    x(Ry),       (see bang_stack_with_offset())

 //    stdu   R1_SP, x(R1_SP),    (see push_frame(), resize_frame())

 // or stdux  R1_SP, Rx, R1_SP    (see push_frame(), resize_frame())

 // return the banged address. Otherwise, return 0.

 address MacroAssembler::get_stack_bang_address(int instruction, void *ucontext) {

 #ifdef LINUX

   ucontext_t* uc = (ucontext_t*) ucontext;

   int rs = inv_rs_field(instruction);

   int ra = inv_ra_field(instruction);

   if (   (is_ld(instruction)   && rs == 0 &&  UseLoadInstructionsForStackBangingPPC64)

       || (is_std(instruction)  && rs == 0 && !UseLoadInstructionsForStackBangingPPC64)

       || (is_stdu(instruction) && rs == 1)) {

     int ds = inv_ds_field(instruction);

     // return banged address

     return ds+(address)uc->uc_mcontext.regs->gpr[ra];

   } else if (is_stdux(instruction) && rs == 1) {

     int rb = inv_rb_field(instruction);

     address sp = (address)uc->uc_mcontext.regs->gpr[1];

     long rb_val = (long)uc->uc_mcontext.regs->gpr[rb];

     return ra != 1 || rb_val >= 0 ? NULL         // not a stack bang

                                   : sp + rb_val; // banged address

   }

   return NULL; // not a stack bang

 #else

   // workaround not needed on !LINUX :-)

   ShouldNotCallThis();

   return NULL;

 #endif

 }

 // CmpxchgX sets condition register to cmpX(current, compare).

 void MacroAssembler::cmpxchgw(ConditionRegister flag, Register dest_current_value,

                               Register compare_value, Register exchange_value,

                               Register addr_base, int semantics, bool cmpxchgx_hint,

                               Register int_flag_success, bool contention_hint) {

   Label retry;

   Label failed;

   Label done;

   // Save one branch if result is returned via register and

   // result register is different from the other ones.

   bool use_result_reg    = (int_flag_success != noreg);

   bool preset_result_reg = (int_flag_success != dest_current_value && int_flag_success != compare_value &&

                             int_flag_success != exchange_value && int_flag_success != addr_base);

   // release/fence semantics

   if (semantics & MemBarRel) {

     release();

   }

   if (use_result_reg && preset_result_reg) {

     li(int_flag_success, 0); // preset (assume cas failed)

   }

   // Add simple guard in order to reduce risk of starving under high contention (recommended by IBM).

   if (contention_hint) { // Don't try to reserve if cmp fails.

     lwz(dest_current_value, 0, addr_base);

     cmpw(flag, dest_current_value, compare_value);

     bne(flag, failed);

   }

   // atomic emulation loop

   bind(retry);

   lwarx(dest_current_value, addr_base, cmpxchgx_hint);

   cmpw(flag, dest_current_value, compare_value);

   if (UseStaticBranchPredictionInCompareAndSwapPPC64) {

     bne_predict_not_taken(flag, failed);

   } else {

     bne(                  flag, failed);

   }

   // branch to done  => (flag == ne), (dest_current_value != compare_value)

   // fall through    => (flag == eq), (dest_current_value == compare_value)

   stwcx_(exchange_value, addr_base);

   if (UseStaticBranchPredictionInCompareAndSwapPPC64) {

     bne_predict_not_taken(CCR0, retry); // StXcx_ sets CCR0.

   } else {

     bne(                  CCR0, retry); // StXcx_ sets CCR0.

   }

   // fall through    => (flag == eq), (dest_current_value == compare_value), (swapped)

   // Result in register (must do this at the end because int_flag_success can be the

   // same register as one above).

   if (use_result_reg) {

     li(int_flag_success, 1);

   }

   if (semantics & MemBarFenceAfter) {

     fence();

   } else if (semantics & MemBarAcq) {

     isync();

   }

   if (use_result_reg && !preset_result_reg) {

     b(done);

   }

   bind(failed);

   if (use_result_reg && !preset_result_reg) {

     li(int_flag_success, 0);

   }

   bind(done);

   // (flag == ne) => (dest_current_value != compare_value), (!swapped)

   // (flag == eq) => (dest_current_value == compare_value), ( swapped)

 }

 // Preforms atomic compare exchange:

 //   if (compare_value == *addr_base)

 //     *addr_base = exchange_value

 //     int_flag_success = 1;

 //   else

 //     int_flag_success = 0;

 //

 // ConditionRegister flag       = cmp(compare_value, *addr_base)

 // Register dest_current_value  = *addr_base

 // Register compare_value       Used to compare with value in memory

 // Register exchange_value      Written to memory if compare_value == *addr_base

 // Register addr_base           The memory location to compareXChange

 // Register int_flag_success    Set to 1 if exchange_value was written to *addr_base

 //

 // To avoid the costly compare exchange the value is tested beforehand.

 // Several special cases exist to avoid that unnecessary information is generated.

 //

 void MacroAssembler::cmpxchgd(ConditionRegister flag,

                               Register dest_current_value, Register compare_value, Register exchange_value,

                               Register addr_base, int semantics, bool cmpxchgx_hint,

                               Register int_flag_success, Label* failed_ext, bool contention_hint) {

   Label retry;

   Label failed_int;

   Label& failed = (failed_ext != NULL) ? *failed_ext : failed_int;

   Label done;

   // Save one branch if result is returned via register and result register is different from the other ones.

   bool use_result_reg    = (int_flag_success!=noreg);

   bool preset_result_reg = (int_flag_success!=dest_current_value && int_flag_success!=compare_value &&

                             int_flag_success!=exchange_value && int_flag_success!=addr_base);

   assert(int_flag_success == noreg || failed_ext == NULL, "cannot have both");

   // release/fence semantics

   if (semantics & MemBarRel) {

     release();

   }

   if (use_result_reg && preset_result_reg) {

     li(int_flag_success, 0); // preset (assume cas failed)

   }

   // Add simple guard in order to reduce risk of starving under high contention (recommended by IBM).

   if (contention_hint) { // Don't try to reserve if cmp fails.

     ld(dest_current_value, 0, addr_base);

     cmpd(flag, dest_current_value, compare_value);

     bne(flag, failed);

   }

   // atomic emulation loop

   bind(retry);

   ldarx(dest_current_value, addr_base, cmpxchgx_hint);

   cmpd(flag, dest_current_value, compare_value);

   if (UseStaticBranchPredictionInCompareAndSwapPPC64) {

     bne_predict_not_taken(flag, failed);

   } else {

     bne(                  flag, failed);

   }

   stdcx_(exchange_value, addr_base);

   if (UseStaticBranchPredictionInCompareAndSwapPPC64) {

     bne_predict_not_taken(CCR0, retry); // stXcx_ sets CCR0

   } else {

     bne(                  CCR0, retry); // stXcx_ sets CCR0

   }

   // result in register (must do this at the end because int_flag_success can be the same register as one above)

   if (use_result_reg) {

     li(int_flag_success, 1);

   }

   // POWER6 doesn't need isync in CAS.

   // Always emit isync to be on the safe side.

   if (semantics & MemBarFenceAfter) {

     fence();

   } else if (semantics & MemBarAcq) {

     isync();

   }

   if (use_result_reg && !preset_result_reg) {

     b(done);

   }

   bind(failed_int);

   if (use_result_reg && !preset_result_reg) {

     li(int_flag_success, 0);

   }

   bind(done);

   // (flag == ne) => (dest_current_value != compare_value), (!swapped)

   // (flag == eq) => (dest_current_value == compare_value), ( swapped)

 }

 // Look up the method for a megamorphic invokeinterface call.

 // The target method is determined by <intf_klass, itable_index>.

 // The receiver klass is in recv_klass.

 // On success, the result will be in method_result, and execution falls through.

 // On failure, execution transfers to the given label.

 void MacroAssembler::lookup_interface_method(Register recv_klass,

                                              Register intf_klass,

                                              RegisterOrConstant itable_index,

                                              Register method_result,

                                              Register scan_temp,

                                              Register sethi_temp,

                                              Label& L_no_such_interface) {

   assert_different_registers(recv_klass, intf_klass, method_result, scan_temp);

   assert(itable_index.is_constant() || itable_index.as_register() == method_result,

          "caller must use same register for non-constant itable index as for method");

   // Compute start of first itableOffsetEntry (which is at the end of the vtable).

   int vtable_base = InstanceKlass::vtable_start_offset() * wordSize;

   int itentry_off = itableMethodEntry::method_offset_in_bytes();

   int logMEsize   = exact_log2(itableMethodEntry::size() * wordSize);

   int scan_step   = itableOffsetEntry::size() * wordSize;

   int log_vte_size= exact_log2(vtableEntry::size() * wordSize);

   lwz(scan_temp, InstanceKlass::vtable_length_offset() * wordSize, recv_klass);

   // %%% We should store the aligned, prescaled offset in the klassoop.

   // Then the next several instructions would fold away.

   sldi(scan_temp, scan_temp, log_vte_size);

   addi(scan_temp, scan_temp, vtable_base);

   add(scan_temp, recv_klass, scan_temp);

   // Adjust recv_klass by scaled itable_index, so we can free itable_index.

   if (itable_index.is_register()) {

     Register itable_offset = itable_index.as_register();

     sldi(itable_offset, itable_offset, logMEsize);

     if (itentry_off) addi(itable_offset, itable_offset, itentry_off);

     add(recv_klass, itable_offset, recv_klass);

   } else {

     long itable_offset = (long)itable_index.as_constant();

     load_const_optimized(sethi_temp, (itable_offset<<logMEsize)+itentry_off); // static address, no relocation

     add(recv_klass, sethi_temp, recv_klass);

   }

   // for (scan = klass->itable(); scan->interface() != NULL; scan += scan_step) {

   //   if (scan->interface() == intf) {

   //     result = (klass + scan->offset() + itable_index);

   //   }

   // }

   Label search, found_method;

   for (int peel = 1; peel >= 0; peel--) {

     // %%%% Could load both offset and interface in one ldx, if they were

     // in the opposite order. This would save a load.

     ld(method_result, itableOffsetEntry::interface_offset_in_bytes(), scan_temp);

     // Check that this entry is non-null. A null entry means that

     // the receiver class doesn't implement the interface, and wasn't the

     // same as when the caller was compiled.

     cmpd(CCR0, method_result, intf_klass);

     if (peel) {

       beq(CCR0, found_method);

     } else {

       bne(CCR0, search);

       // (invert the test to fall through to found_method...)

     }

     if (!peel) break;

     bind(search);

     cmpdi(CCR0, method_result, 0);

     beq(CCR0, L_no_such_interface);

     addi(scan_temp, scan_temp, scan_step);

   }

   bind(found_method);

   // Got a hit.

   int ito_offset = itableOffsetEntry::offset_offset_in_bytes();

   lwz(scan_temp, ito_offset, scan_temp);

   ldx(method_result, scan_temp, recv_klass);

 }

 // virtual method calling

 void MacroAssembler::lookup_virtual_method(Register recv_klass,

                                            RegisterOrConstant vtable_index,

                                            Register method_result) {

   assert_different_registers(recv_klass, method_result, vtable_index.register_or_noreg());

   const int base = InstanceKlass::vtable_start_offset() * wordSize;

   assert(vtableEntry::size() * wordSize == wordSize, "adjust the scaling in the code below");

   if (vtable_index.is_register()) {

     sldi(vtable_index.as_register(), vtable_index.as_register(), LogBytesPerWord);

     add(recv_klass, vtable_index.as_register(), recv_klass);

   } else {

     addi(recv_klass, recv_klass, vtable_index.as_constant() << LogBytesPerWord);

   }

   ld(R19_method, base + vtableEntry::method_offset_in_bytes(), recv_klass);

 }

 /////////////////////////////////////////// subtype checking ////////////////////////////////////////////

 void MacroAssembler::check_klass_subtype_fast_path(Register sub_klass,

                                                    Register super_klass,

                                                    Register temp1_reg,

                                                    Register temp2_reg,

                                                    Label& L_success,

                                                    Label& L_failure) {

   const Register check_cache_offset = temp1_reg;

   const Register cached_super       = temp2_reg;

   assert_different_registers(sub_klass, super_klass, check_cache_offset, cached_super);

   int sco_offset = in_bytes(Klass::super_check_offset_offset());

   int sc_offset  = in_bytes(Klass::secondary_super_cache_offset());

   // If the pointers are equal, we are done (e.g., String[] elements).

   // This self-check enables sharing of secondary supertype arrays among

   // non-primary types such as array-of-interface. Otherwise, each such

   // type would need its own customized SSA.

   // We move this check to the front of the fast path because many

   // type checks are in fact trivially successful in this manner,

   // so we get a nicely predicted branch right at the start of the check.

   cmpd(CCR0, sub_klass, super_klass);

   beq(CCR0, L_success);

   // Check the supertype display:

   lwz(check_cache_offset, sco_offset, super_klass);

   // The loaded value is the offset from KlassOopDesc.

   ldx(cached_super, check_cache_offset, sub_klass);

   cmpd(CCR0, cached_super, super_klass);

   beq(CCR0, L_success);

   // This check has worked decisively for primary supers.

   // Secondary supers are sought in the super_cache ('super_cache_addr').

   // (Secondary supers are interfaces and very deeply nested subtypes.)

   // This works in the same check above because of a tricky aliasing

   // between the super_cache and the primary super display elements.

   // (The 'super_check_addr' can address either, as the case requires.)

   // Note that the cache is updated below if it does not help us find

   // what we need immediately.

   // So if it was a primary super, we can just fail immediately.

   // Otherwise, it's the slow path for us (no success at this point).

   cmpwi(CCR0, check_cache_offset, sc_offset);

   bne(CCR0, L_failure);

   // bind(slow_path); // fallthru

 }

 void MacroAssembler::check_klass_subtype_slow_path(Register sub_klass,

                                                    Register super_klass,

                                                    Register temp1_reg,

                                                    Register temp2_reg,

                                                    Label* L_success,

                                                    Register result_reg) {

   const Register array_ptr = temp1_reg; // current value from cache array

   const Register temp      = temp2_reg;

   assert_different_registers(sub_klass, super_klass, array_ptr, temp);

   int source_offset = in_bytes(Klass::secondary_supers_offset());

   int target_offset = in_bytes(Klass::secondary_super_cache_offset());

   int length_offset = Array<Klass*>::length_offset_in_bytes();

   int base_offset   = Array<Klass*>::base_offset_in_bytes();

   Label hit, loop, failure, fallthru;

   ld(array_ptr, source_offset, sub_klass);

   //assert(4 == arrayOopDesc::length_length_in_bytes(), "precondition violated.");

   lwz(temp, length_offset, array_ptr);

   cmpwi(CCR0, temp, 0);

   beq(CCR0, result_reg!=noreg ? failure : fallthru); // length 0

   mtctr(temp); // load ctr

   bind(loop);

   // Oops in table are NO MORE compressed.

   ld(temp, base_offset, array_ptr);

   cmpd(CCR0, temp, super_klass);

   beq(CCR0, hit);

   addi(array_ptr, array_ptr, BytesPerWord);

   bdnz(loop);

   bind(failure);

   if (result_reg!=noreg) li(result_reg, 1); // load non-zero result (indicates a miss)

   b(fallthru);

   bind(hit);

   std(super_klass, target_offset, sub_klass); // save result to cache

   if (result_reg != noreg) li(result_reg, 0); // load zero result (indicates a hit)

   if (L_success != NULL) b(*L_success);

   bind(fallthru);

 }

 // Try fast path, then go to slow one if not successful

 void MacroAssembler::check_klass_subtype(Register sub_klass,

                          Register super_klass,

                          Register temp1_reg,

                          Register temp2_reg,

                          Label& L_success) {

   Label L_failure;

   check_klass_subtype_fast_path(sub_klass, super_klass, temp1_reg, temp2_reg, L_success, L_failure);

   check_klass_subtype_slow_path(sub_klass, super_klass, temp1_reg, temp2_reg, &L_success);

   bind(L_failure); // Fallthru if not successful.

 }

 void MacroAssembler::check_method_handle_type(Register mtype_reg, Register mh_reg,

                                               Register temp_reg,

                                               Label& wrong_method_type) {

   assert_different_registers(mtype_reg, mh_reg, temp_reg);

   // Compare method type against that of the receiver.

   load_heap_oop_not_null(temp_reg, delayed_value(java_lang_invoke_MethodHandle::type_offset_in_bytes, temp_reg), mh_reg);

   cmpd(CCR0, temp_reg, mtype_reg);

   bne(CCR0, wrong_method_type);

 }

 RegisterOrConstant MacroAssembler::argument_offset(RegisterOrConstant arg_slot,

                                                    Register temp_reg,

                                                    int extra_slot_offset) {

   // cf. TemplateTable::prepare_invoke(), if (load_receiver).

   int stackElementSize = Interpreter::stackElementSize;

   int offset = extra_slot_offset * stackElementSize;

   if (arg_slot.is_constant()) {

     offset += arg_slot.as_constant() * stackElementSize;

     return offset;

   } else {

     assert(temp_reg != noreg, "must specify");

     sldi(temp_reg, arg_slot.as_register(), exact_log2(stackElementSize));

     if (offset != 0)

       addi(temp_reg, temp_reg, offset);

     return temp_reg;

   }

 }

 void MacroAssembler::biased_locking_enter(ConditionRegister cr_reg, Register obj_reg,

                                           Register mark_reg, Register temp_reg,

                                           Register temp2_reg, Label& done, Label* slow_case) {

   assert(UseBiasedLocking, "why call this otherwise?");

 #ifdef ASSERT

   assert_different_registers(obj_reg, mark_reg, temp_reg, temp2_reg);

 #endif

   Label cas_label;

   // Branch to done if fast path fails and no slow_case provided.

   Label *slow_case_int = (slow_case != NULL) ? slow_case : &done;

   // Biased locking

   // See whether the lock is currently biased toward our thread and

   // whether the epoch is still valid

   // Note that the runtime guarantees sufficient alignment of JavaThread

   // pointers to allow age to be placed into low bits

   assert(markOopDesc::age_shift == markOopDesc::lock_bits + markOopDesc::biased_lock_bits,

          "biased locking makes assumptions about bit layout");

   if (PrintBiasedLockingStatistics) {

     load_const(temp_reg, (address) BiasedLocking::total_entry_count_addr(), temp2_reg);

     lwz(temp2_reg, 0, temp_reg);

     addi(temp2_reg, temp2_reg, 1);

     stw(temp2_reg, 0, temp_reg);

   }

   andi(temp_reg, mark_reg, markOopDesc::biased_lock_mask_in_place);

   cmpwi(cr_reg, temp_reg, markOopDesc::biased_lock_pattern);

   bne(cr_reg, cas_label);

   load_klass_with_trap_null_check(temp_reg, obj_reg);

   load_const_optimized(temp2_reg, ~((int) markOopDesc::age_mask_in_place));

   ld(temp_reg, in_bytes(Klass::prototype_header_offset()), temp_reg);

   orr(temp_reg, R16_thread, temp_reg);

   xorr(temp_reg, mark_reg, temp_reg);

   andr(temp_reg, temp_reg, temp2_reg);

   cmpdi(cr_reg, temp_reg, 0);

   if (PrintBiasedLockingStatistics) {

     Label l;

     bne(cr_reg, l);

     load_const(mark_reg, (address) BiasedLocking::biased_lock_entry_count_addr());

     lwz(temp2_reg, 0, mark_reg);

     addi(temp2_reg, temp2_reg, 1);

     stw(temp2_reg, 0, mark_reg);

     // restore mark_reg

     ld(mark_reg, oopDesc::mark_offset_in_bytes(), obj_reg);

     bind(l);

   }

   beq(cr_reg, done);

   Label try_revoke_bias;

   Label try_rebias;

   // At this point we know that the header has the bias pattern and

   // that we are not the bias owner in the current epoch. We need to

   // figure out more details about the state of the header in order to

   // know what operations can be legally performed on the object's

   // header.

   // If the low three bits in the xor result aren't clear, that means

   // the prototype header is no longer biased and we have to revoke

   // the bias on this object.

   andi(temp2_reg, temp_reg, markOopDesc::biased_lock_mask_in_place);

   cmpwi(cr_reg, temp2_reg, 0);

   bne(cr_reg, try_revoke_bias);

   // Biasing is still enabled for this data type. See whether the

   // epoch of the current bias is still valid, meaning that the epoch

   // bits of the mark word are equal to the epoch bits of the

   // prototype header. (Note that the prototype header's epoch bits

   // only change at a safepoint.) If not, attempt to rebias the object

   // toward the current thread. Note that we must be absolutely sure

   // that the current epoch is invalid in order to do this because

   // otherwise the manipulations it performs on the mark word are

   // illegal.

   int shift_amount = 64 - markOopDesc::epoch_shift;

   // rotate epoch bits to right (little) end and set other bits to 0

   // [ big part | epoch | little part ] -> [ 0..0 | epoch ]

   rldicl_(temp2_reg, temp_reg, shift_amount, 64 - markOopDesc::epoch_bits);

   // branch if epoch bits are != 0, i.e. they differ, because the epoch has been incremented

   bne(CCR0, try_rebias);

   // The epoch of the current bias is still valid but we know nothing

   // about the owner; it might be set or it might be clear. Try to

   // acquire the bias of the object using an atomic operation. If this

   // fails we will go in to the runtime to revoke the object's bias.

   // Note that we first construct the presumed unbiased header so we

   // don't accidentally blow away another thread's valid bias.

   andi(mark_reg, mark_reg, (markOopDesc::biased_lock_mask_in_place |

                                 markOopDesc::age_mask_in_place |

                                 markOopDesc::epoch_mask_in_place));

   orr(temp_reg, R16_thread, mark_reg);

   assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");

   // CmpxchgX sets cr_reg to cmpX(temp2_reg, mark_reg).

   fence(); // TODO: replace by MacroAssembler::MemBarRel | MacroAssembler::MemBarAcq ?

   cmpxchgd(/*flag=*/cr_reg, /*current_value=*/temp2_reg,

            /*compare_value=*/mark_reg, /*exchange_value=*/temp_reg,

            /*where=*/obj_reg,

            MacroAssembler::MemBarAcq,

            MacroAssembler::cmpxchgx_hint_acquire_lock(),

            noreg, slow_case_int); // bail out if failed

   // If the biasing toward our thread failed, this means that

   // another thread succeeded in biasing it toward itself and we

   // need to revoke that bias. The revocation will occur in the

   // interpreter runtime in the slow case.

   if (PrintBiasedLockingStatistics) {

     load_const(temp_reg, (address) BiasedLocking::anonymously_biased_lock_entry_count_addr(), temp2_reg);

     lwz(temp2_reg, 0, temp_reg);

     addi(temp2_reg, temp2_reg, 1);

     stw(temp2_reg, 0, temp_reg);

   }

   b(done);

   bind(try_rebias);

   // At this point we know the epoch has expired, meaning that the

   // current "bias owner", if any, is actually invalid. Under these

   // circumstances _only_, we are allowed to use the current header's

   // value as the comparison value when doing the cas to acquire the

   // bias in the current epoch. In other words, we allow transfer of

   // the bias from one thread to another directly in this situation.

   andi(temp_reg, mark_reg, markOopDesc::age_mask_in_place);

   orr(temp_reg, R16_thread, temp_reg);

   load_klass_with_trap_null_check(temp2_reg, obj_reg);

   ld(temp2_reg, in_bytes(Klass::prototype_header_offset()), temp2_reg);

   orr(temp_reg, temp_reg, temp2_reg);

   assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");

   // CmpxchgX sets cr_reg to cmpX(temp2_reg, mark_reg).

   fence(); // TODO: replace by MacroAssembler::MemBarRel | MacroAssembler::MemBarAcq ?

   cmpxchgd(/*flag=*/cr_reg, /*current_value=*/temp2_reg,

                  /*compare_value=*/mark_reg, /*exchange_value=*/temp_reg,

                  /*where=*/obj_reg,

                  MacroAssembler::MemBarAcq,

                  MacroAssembler::cmpxchgx_hint_acquire_lock(),

                  noreg, slow_case_int); // bail out if failed

   // If the biasing toward our thread failed, this means that

   // another thread succeeded in biasing it toward itself and we

   // need to revoke that bias. The revocation will occur in the

   // interpreter runtime in the slow case.

   if (PrintBiasedLockingStatistics) {

     load_const(temp_reg, (address) BiasedLocking::rebiased_lock_entry_count_addr(), temp2_reg);

     lwz(temp2_reg, 0, temp_reg);

     addi(temp2_reg, temp2_reg, 1);

     stw(temp2_reg, 0, temp_reg);

   }

   b(done);

   bind(try_revoke_bias);

   // The prototype mark in the klass doesn't have the bias bit set any

   // more, indicating that objects of this data type are not supposed

   // to be biased any more. We are going to try to reset the mark of

   // this object to the prototype value and fall through to the

   // CAS-based locking scheme. Note that if our CAS fails, it means

   // that another thread raced us for the privilege of revoking the

   // bias of this particular object, so it's okay to continue in the

   // normal locking code.

   load_klass_with_trap_null_check(temp_reg, obj_reg);

   ld(temp_reg, in_bytes(Klass::prototype_header_offset()), temp_reg);

   andi(temp2_reg, mark_reg, markOopDesc::age_mask_in_place);

   orr(temp_reg, temp_reg, temp2_reg);

   assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");

   // CmpxchgX sets cr_reg to cmpX(temp2_reg, mark_reg).

   fence(); // TODO: replace by MacroAssembler::MemBarRel | MacroAssembler::MemBarAcq ?

   cmpxchgd(/*flag=*/cr_reg, /*current_value=*/temp2_reg,

                  /*compare_value=*/mark_reg, /*exchange_value=*/temp_reg,

                  /*where=*/obj_reg,

                  MacroAssembler::MemBarAcq,

                  MacroAssembler::cmpxchgx_hint_acquire_lock());

   // reload markOop in mark_reg before continuing with lightweight locking

   ld(mark_reg, oopDesc::mark_offset_in_bytes(), obj_reg);

   // Fall through to the normal CAS-based lock, because no matter what

   // the result of the above CAS, some thread must have succeeded in

   // removing the bias bit from the object's header.

   if (PrintBiasedLockingStatistics) {

     Label l;

     bne(cr_reg, l);

     load_const(temp_reg, (address) BiasedLocking::revoked_lock_entry_count_addr(), temp2_reg);

     lwz(temp2_reg, 0, temp_reg);

     addi(temp2_reg, temp2_reg, 1);

     stw(temp2_reg, 0, temp_reg);

     bind(l);

   }

   bind(cas_label);

 }

 void MacroAssembler::biased_locking_exit (ConditionRegister cr_reg, Register mark_addr, Register temp_reg, Label& done) {

   // Check for biased locking unlock case, which is a no-op

   // Note: we do not have to check the thread ID for two reasons.

   // First, the interpreter checks for IllegalMonitorStateException at

   // a higher level. Second, if the bias was revoked while we held the

   // lock, the object could not be rebiased toward another thread, so

   // the bias bit would be clear.

   ld(temp_reg, 0, mark_addr);

   andi(temp_reg, temp_reg, markOopDesc::biased_lock_mask_in_place);

   cmpwi(cr_reg, temp_reg, markOopDesc::biased_lock_pattern);

   beq(cr_reg, done);

 }

 // "The box" is the space on the stack where we copy the object mark.

 void MacroAssembler::compiler_fast_lock_object(ConditionRegister flag, Register oop, Register box,

                                                Register temp, Register displaced_header, Register current_header) {

   assert_different_registers(oop, box, temp, displaced_header, current_header);

   assert(flag != CCR0, "bad condition register");

   Label cont;

   Label object_has_monitor;

   Label cas_failed;

   // Load markOop from object into displaced_header.

   ld(displaced_header, oopDesc::mark_offset_in_bytes(), oop);

   // Always do locking in runtime.

   if (EmitSync & 0x01) {

     cmpdi(flag, oop, 0); // Oop can't be 0 here => always false.

     return;

   }

   if (UseBiasedLocking) {

     biased_locking_enter(flag, oop, displaced_header, temp, current_header, cont);

   }

   // Handle existing monitor.

   if ((EmitSync & 0x02) == 0) {

     // The object has an existing monitor iff (mark & monitor_value) != 0.

     andi_(temp, displaced_header, markOopDesc::monitor_value);

     bne(CCR0, object_has_monitor);

   }

   // Set displaced_header to be (markOop of object | UNLOCK_VALUE).

   ori(displaced_header, displaced_header, markOopDesc::unlocked_value);

   // Load Compare Value application register.

   // Initialize the box. (Must happen before we update the object mark!)

   std(displaced_header, BasicLock::displaced_header_offset_in_bytes(), box);

   // Must fence, otherwise, preceding store(s) may float below cmpxchg.

   // Compare object markOop with mark and if equal exchange scratch1 with object markOop.

   // CmpxchgX sets cr_reg to cmpX(current, displaced).

   cmpxchgd(/*flag=*/flag,

            /*current_value=*/current_header,

            /*compare_value=*/displaced_header,

            /*exchange_value=*/box,

            /*where=*/oop,

            MacroAssembler::MemBarRel | MacroAssembler::MemBarAcq,

            MacroAssembler::cmpxchgx_hint_acquire_lock(),

            noreg,

            &cas_failed);

   assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");

   // If the compare-and-exchange succeeded, then we found an unlocked

   // object and we have now locked it.

   b(cont);

   bind(cas_failed);

   // We did not see an unlocked object so try the fast recursive case.

   // Check if the owner is self by comparing the value in the markOop of object

   // (current_header) with the stack pointer.

   sub(current_header, current_header, R1_SP);

   load_const_optimized(temp, (address) (~(os::vm_page_size()-1) |

                                         markOopDesc::lock_mask_in_place));

   and_(R0/*==0?*/, current_header, temp);

   // If condition is true we are cont and hence we can store 0 as the

   // displaced header in the box, which indicates that it is a recursive lock.

   mcrf(flag,CCR0);

   std(R0/*==0, perhaps*/, BasicLock::displaced_header_offset_in_bytes(), box);

   // Handle existing monitor.

   if ((EmitSync & 0x02) == 0) {

     b(cont);

     bind(object_has_monitor);

     // The object's monitor m is unlocked iff m->owner == NULL,

     // otherwise m->owner may contain a thread or a stack address.

     //

     // Try to CAS m->owner from NULL to current thread.

     addi(temp, displaced_header, ObjectMonitor::owner_offset_in_bytes()-markOopDesc::monitor_value);

     li(displaced_header, 0);

     // CmpxchgX sets flag to cmpX(current, displaced).

     cmpxchgd(/*flag=*/flag,

              /*current_value=*/current_header,

              /*compare_value=*/displaced_header,

              /*exchange_value=*/R16_thread,

              /*where=*/temp,

              MacroAssembler::MemBarRel | MacroAssembler::MemBarAcq,

              MacroAssembler::cmpxchgx_hint_acquire_lock());

     // Store a non-null value into the box.

     std(box, BasicLock::displaced_header_offset_in_bytes(), box);

 #   ifdef ASSERT

     bne(flag, cont);

     // We have acquired the monitor, check some invariants.

     addi(/*monitor=*/temp, temp, -ObjectMonitor::owner_offset_in_bytes());

     // Invariant 1: _recursions should be 0.

     //assert(ObjectMonitor::recursions_size_in_bytes() == 8, "unexpected size");

     asm_assert_mem8_is_zero(ObjectMonitor::recursions_offset_in_bytes(), temp,

                             "monitor->_recursions should be 0", -1);

     // Invariant 2: OwnerIsThread shouldn't be 0.

     //assert(ObjectMonitor::OwnerIsThread_size_in_bytes() == 4, "unexpected size");

     //asm_assert_mem4_isnot_zero(ObjectMonitor::OwnerIsThread_offset_in_bytes(), temp,

     //                           "monitor->OwnerIsThread shouldn't be 0", -1);

 #   endif

   }

   bind(cont);

   // flag == EQ indicates success

   // flag == NE indicates failure

 }

 void MacroAssembler::compiler_fast_unlock_object(ConditionRegister flag, Register oop, Register box,

                                                  Register temp, Register displaced_header, Register current_header) {

   assert_different_registers(oop, box, temp, displaced_header, current_header);

   assert(flag != CCR0, "bad condition register");

   Label cont;

   Label object_has_monitor;

   // Always do locking in runtime.

   if (EmitSync & 0x01) {

     cmpdi(flag, oop, 0); // Oop can't be 0 here => always false.

     return;

   }

   if (UseBiasedLocking) {

     biased_locking_exit(flag, oop, current_header, cont);

   }

   // Find the lock address and load the displaced header from the stack.

   ld(displaced_header, BasicLock::displaced_header_offset_in_bytes(), box);

   // If the displaced header is 0, we have a recursive unlock.

   cmpdi(flag, displaced_header, 0);

   beq(flag, cont);

   // Handle existing monitor.

   if ((EmitSync & 0x02) == 0) {

     // The object has an existing monitor iff (mark & monitor_value) != 0.

     ld(current_header, oopDesc::mark_offset_in_bytes(), oop);

     andi(temp, current_header, markOopDesc::monitor_value);

     cmpdi(flag, temp, 0);

     bne(flag, object_has_monitor);

   }

   // Check if it is still a light weight lock, this is is true if we see

   // the stack address of the basicLock in the markOop of the object.

   // Cmpxchg sets flag to cmpd(current_header, box).

   cmpxchgd(/*flag=*/flag,

            /*current_value=*/current_header,

            /*compare_value=*/box,

            /*exchange_value=*/displaced_header,

            /*where=*/oop,

            MacroAssembler::MemBarRel,

            MacroAssembler::cmpxchgx_hint_release_lock(),

            noreg,

            &cont);

   assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");

   // Handle existing monitor.

   if ((EmitSync & 0x02) == 0) {

     b(cont);

     bind(object_has_monitor);

     addi(current_header, current_header, -markOopDesc::monitor_value); // monitor

     ld(temp,             ObjectMonitor::owner_offset_in_bytes(), current_header);

     ld(displaced_header, ObjectMonitor::recursions_offset_in_bytes(), current_header);

     xorr(temp, R16_thread, temp);      // Will be 0 if we are the owner.

     orr(temp, temp, displaced_header); // Will be 0 if there are 0 recursions.

     cmpdi(flag, temp, 0);

     bne(flag, cont);

     ld(temp,             ObjectMonitor::EntryList_offset_in_bytes(), current_header);

     ld(displaced_header, ObjectMonitor::cxq_offset_in_bytes(), current_header);

     orr(temp, temp, displaced_header); // Will be 0 if both are 0.

     cmpdi(flag, temp, 0);

     bne(flag, cont);

     release();

     std(temp, ObjectMonitor::owner_offset_in_bytes(), current_header);

   }

   bind(cont);

   // flag == EQ indicates success

   // flag == NE indicates failure

 }

 // Write serialization page so 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.

 void MacroAssembler::serialize_memory(Register thread, Register tmp1, Register tmp2) {

   srdi(tmp2, thread, os::get_serialize_page_shift_count());

   int mask = os::vm_page_size() - sizeof(int);

   if (Assembler::is_simm(mask, 16)) {

     andi(tmp2, tmp2, mask);

   } else {

     lis(tmp1, (int)((signed short) (mask >> 16)));

     ori(tmp1, tmp1, mask & 0x0000ffff);

     andr(tmp2, tmp2, tmp1);

   }

   load_const(tmp1, (long) os::get_memory_serialize_page());

   release();

   stwx(R0, tmp1, tmp2);

 }

 // GC barrier helper macros

 // Write the card table byte if needed.

 void MacroAssembler::card_write_barrier_post(Register Rstore_addr, Register Rnew_val, Register Rtmp) {

   CardTableModRefBS* bs = (CardTableModRefBS*) Universe::heap()->barrier_set();

   assert(bs->kind() == BarrierSet::CardTableModRef ||

          bs->kind() == BarrierSet::CardTableExtension, "wrong barrier");

 #ifdef ASSERT

   cmpdi(CCR0, Rnew_val, 0);

   asm_assert_ne("null oop not allowed", 0x321);

 #endif

   card_table_write(bs->byte_map_base, Rtmp, Rstore_addr);

 }

 // Write the card table byte.

 void MacroAssembler::card_table_write(jbyte* byte_map_base, Register Rtmp, Register Robj) {

   assert_different_registers(Robj, Rtmp, R0);

   load_const_optimized(Rtmp, (address)byte_map_base, R0);

   srdi(Robj, Robj, CardTableModRefBS::card_shift);

   li(R0, 0); // dirty

   if (UseConcMarkSweepGC) release();

   stbx(R0, Rtmp, Robj);

 }

 #ifndef SERIALGC

 // General G1 pre-barrier generator.

 // Goal: record the previous value if it is not null.

 void MacroAssembler::g1_write_barrier_pre(Register Robj, RegisterOrConstant offset, Register Rpre_val,

                                           Register Rtmp1, Register Rtmp2, bool needs_frame) {

   Label runtime, filtered;

   // Is marking active?

   if (in_bytes(PtrQueue::byte_width_of_active()) == 4) {

     lwz(Rtmp1, in_bytes(JavaThread::satb_mark_queue_offset() + PtrQueue::byte_offset_of_active()), R16_thread);

   } else {

     guarantee(in_bytes(PtrQueue::byte_width_of_active()) == 1, "Assumption");

     lbz(Rtmp1, in_bytes(JavaThread::satb_mark_queue_offset() + PtrQueue::byte_offset_of_active()), R16_thread);

   }

   cmpdi(CCR0, Rtmp1, 0);

   beq(CCR0, filtered);

   // Do we need to load the previous value?

   if (Robj != noreg) {

     // Load the previous value...

     if (UseCompressedOops) {

       lwz(Rpre_val, offset, Robj);

     } else {

       ld(Rpre_val, offset, Robj);

     }

     // Previous value has been loaded into Rpre_val.

   }

   assert(Rpre_val != noreg, "must have a real register");

   // Is the previous value null?

   cmpdi(CCR0, Rpre_val, 0);

   beq(CCR0, filtered);

   if (Robj != noreg && UseCompressedOops) {

     decode_heap_oop_not_null(Rpre_val);

   }

   // OK, it's not filtered, so we'll need to call enqueue. In the normal

   // case, pre_val will be a scratch G-reg, but there are some cases in

   // which it's an O-reg. In the first case, do a normal call. In the

   // latter, do a save here and call the frameless version.

   // Can we store original value in the thread's buffer?

   // Is index == 0?

   // (The index field is typed as size_t.)

   const Register Rbuffer = Rtmp1, Rindex = Rtmp2;

   ld(Rindex, in_bytes(JavaThread::satb_mark_queue_offset() + PtrQueue::byte_offset_of_index()), R16_thread);

   cmpdi(CCR0, Rindex, 0);

   beq(CCR0, runtime); // If index == 0, goto runtime.

   ld(Rbuffer, in_bytes(JavaThread::satb_mark_queue_offset() + PtrQueue::byte_offset_of_buf()), R16_thread);

   addi(Rindex, Rindex, -wordSize); // Decrement index.

   std(Rindex, in_bytes(JavaThread::satb_mark_queue_offset() + PtrQueue::byte_offset_of_index()), R16_thread);

   // Record the previous value.

   stdx(Rpre_val, Rbuffer, Rindex);

   b(filtered);

   bind(runtime);

   // VM call need frame to access(write) O register.

   if (needs_frame) {

     save_LR_CR(Rtmp1);

     push_frame_abi112(0, Rtmp2);

   }

   if (Rpre_val->is_volatile() && Robj == noreg) mr(R31, Rpre_val); // Save pre_val across C call if it was preloaded.

   call_VM_leaf(CAST_FROM_FN_PTR(address, SharedRuntime::g1_wb_pre), Rpre_val, R16_thread);

   if (Rpre_val->is_volatile() && Robj == noreg) mr(Rpre_val, R31); // restore

   if (needs_frame) {

     pop_frame();

     restore_LR_CR(Rtmp1);

   }

   bind(filtered);

 }

 // General G1 post-barrier generator

 // Store cross-region card.

 void MacroAssembler::g1_write_barrier_post(Register Rstore_addr, Register Rnew_val, Register Rtmp1, Register Rtmp2, Register Rtmp3, Label *filtered_ext) {

   Label runtime, filtered_int;

   Label& filtered = (filtered_ext != NULL) ? *filtered_ext : filtered_int;

   assert_different_registers(Rstore_addr, Rnew_val, Rtmp1, Rtmp2);

   G1SATBCardTableModRefBS* bs = (G1SATBCardTableModRefBS*) Universe::heap()->barrier_set();

   assert(bs->kind() == BarrierSet::G1SATBCT ||

          bs->kind() == BarrierSet::G1SATBCTLogging, "wrong barrier");

   // Does store cross heap regions?

   if (G1RSBarrierRegionFilter) {

     xorr(Rtmp1, Rstore_addr, Rnew_val);

     srdi_(Rtmp1, Rtmp1, HeapRegion::LogOfHRGrainBytes);

     beq(CCR0, filtered);

   }

   // Crosses regions, storing NULL?

 #ifdef ASSERT

   cmpdi(CCR0, Rnew_val, 0);

   asm_assert_ne("null oop not allowed (G1)", 0x322); // Checked by caller on PPC64, so following branch is obsolete:

   //beq(CCR0, filtered);

 #endif

   // Storing region crossing non-NULL, is card already dirty?

   assert(sizeof(*bs->byte_map_base) == sizeof(jbyte), "adjust this code");

   const Register Rcard_addr = Rtmp1;

   Register Rbase = Rtmp2;

   load_const_optimized(Rbase, (address)bs->byte_map_base, /*temp*/ Rtmp3);

   srdi(Rcard_addr, Rstore_addr, CardTableModRefBS::card_shift);

   // Get the address of the card.

   lbzx(/*card value*/ Rtmp3, Rbase, Rcard_addr);

   assert(CardTableModRefBS::dirty_card_val() == 0, "otherwise check this code");

   cmpwi(CCR0, Rtmp3 /* card value */, 0);

   beq(CCR0, filtered);

   // Storing a region crossing, non-NULL oop, card is clean.

   // Dirty card and log.

   li(Rtmp3, 0); // dirty

   //release(); // G1: oops are allowed to get visible after dirty marking.

   stbx(Rtmp3, Rbase, Rcard_addr);

   add(Rcard_addr, Rbase, Rcard_addr); // This is the address which needs to get enqueued.

   Rbase = noreg; // end of lifetime

   const Register Rqueue_index = Rtmp2,

                  Rqueue_buf   = Rtmp3;

   ld(Rqueue_index, in_bytes(JavaThread::dirty_card_queue_offset() + PtrQueue::byte_offset_of_index()), R16_thread);

   cmpdi(CCR0, Rqueue_index, 0);

   beq(CCR0, runtime); // index == 0 then jump to runtime

   ld(Rqueue_buf, in_bytes(JavaThread::dirty_card_queue_offset() + PtrQueue::byte_offset_of_buf()), R16_thread);

   addi(Rqueue_index, Rqueue_index, -wordSize); // decrement index

   std(Rqueue_index, in_bytes(JavaThread::dirty_card_queue_offset() + PtrQueue::byte_offset_of_index()), R16_thread);

   stdx(Rcard_addr, Rqueue_buf, Rqueue_index); // store card

   b(filtered);

   bind(runtime);

   // Save the live input values.

   call_VM_leaf(CAST_FROM_FN_PTR(address, SharedRuntime::g1_wb_post), Rcard_addr, R16_thread);

   bind(filtered_int);

 }

 #endif // SERIALGC

 // Values for last_Java_pc, and last_Java_sp must comply to the rules

 // in frame_ppc64.hpp.

 void MacroAssembler::set_last_Java_frame(Register last_Java_sp, Register last_Java_pc) {

   // Always set last_Java_pc and flags first because once last_Java_sp

   // is visible has_last_Java_frame is true and users will look at the

   // rest of the fields. (Note: flags should always be zero before we

   // get here so doesn't need to be set.)

   // Verify that last_Java_pc was zeroed on return to Java

   asm_assert_mem8_is_zero(in_bytes(JavaThread::last_Java_pc_offset()), R16_thread,

                           "last_Java_pc not zeroed before leaving Java", 0x200);

   // When returning from calling out from Java mode the frame anchor's

   // last_Java_pc will always be set to NULL. It is set here so that

   // if we are doing a call to native (not VM) that we capture the

   // known pc and don't have to rely on the native call having a

   // standard frame linkage where we can find the pc.

   if (last_Java_pc != noreg)

     std(last_Java_pc, in_bytes(JavaThread::last_Java_pc_offset()), R16_thread);

   // set last_Java_sp last

   std(last_Java_sp, in_bytes(JavaThread::last_Java_sp_offset()), R16_thread);

 }

 void MacroAssembler::reset_last_Java_frame(void) {

   asm_assert_mem8_isnot_zero(in_bytes(JavaThread::last_Java_sp_offset()),

                              R16_thread, "SP was not set, still zero", 0x202);

   BLOCK_COMMENT("reset_last_Java_frame {");

   li(R0, 0);

   // _last_Java_sp = 0

   std(R0, in_bytes(JavaThread::last_Java_sp_offset()), R16_thread);

   // _last_Java_pc = 0

   std(R0, in_bytes(JavaThread::last_Java_pc_offset()), R16_thread);

   BLOCK_COMMENT("} reset_last_Java_frame");

 }

 void MacroAssembler::set_top_ijava_frame_at_SP_as_last_Java_frame(Register sp, Register tmp1) {

   assert_different_registers(sp, tmp1);

   // sp points to a TOP_IJAVA_FRAME, retrieve frame's PC via

   // TOP_IJAVA_FRAME_ABI.

   // FIXME: assert that we really have a TOP_IJAVA_FRAME here!

 #ifdef CC_INTERP

   ld(tmp1/*pc*/, _top_ijava_frame_abi(frame_manager_lr), sp);

 #else

   Unimplemented();

 #endif

   set_last_Java_frame(/*sp=*/sp, /*pc=*/tmp1);

 }

 void MacroAssembler::get_vm_result(Register oop_result) {

   // Read:

   //   R16_thread

   //   R16_thread->in_bytes(JavaThread::vm_result_offset())

   //

   // Updated:

   //   oop_result

   //   R16_thread->in_bytes(JavaThread::vm_result_offset())

   ld(oop_result, in_bytes(JavaThread::vm_result_offset()), R16_thread);

   li(R0, 0);

   std(R0, in_bytes(JavaThread::vm_result_offset()), R16_thread);

   verify_oop(oop_result);

 }

 void MacroAssembler::get_vm_result_2(Register metadata_result) {

   // Read:

   //   R16_thread

   //   R16_thread->in_bytes(JavaThread::vm_result_2_offset())

   //

   // Updated:

   //   metadata_result

   //   R16_thread->in_bytes(JavaThread::vm_result_2_offset())

   ld(metadata_result, in_bytes(JavaThread::vm_result_2_offset()), R16_thread);

   li(R0, 0);

   std(R0, in_bytes(JavaThread::vm_result_2_offset()), R16_thread);

 }

 void MacroAssembler::encode_klass_not_null(Register dst, Register src) {

   if (src == noreg) src = dst;

   if (Universe::narrow_klass_base() != 0) {

     load_const(R0, Universe::narrow_klass_base());

     sub(dst, src, R0);

   }

   if (Universe::narrow_klass_shift() != 0 ||

       Universe::narrow_klass_base() == 0 && src != dst) {  // Move required.

     srdi(dst, src, Universe::narrow_klass_shift());

   }

 }

 void MacroAssembler::store_klass(Register dst_oop, Register klass, Register ck) {

   if (UseCompressedClassPointers) {

     encode_klass_not_null(ck, klass);

     stw(ck, oopDesc::klass_offset_in_bytes(), dst_oop);

   } else {

     std(klass, oopDesc::klass_offset_in_bytes(), dst_oop);

   }

 }

 int MacroAssembler::instr_size_for_decode_klass_not_null() {

   if (!UseCompressedClassPointers) return 0;

   int num_instrs = 1;  // shift or move

   if (Universe::narrow_klass_base() != 0) num_instrs = 7;  // shift + load const + add

   return num_instrs * BytesPerInstWord;

 }

 void MacroAssembler::decode_klass_not_null(Register dst, Register src) {

   if (src == noreg) src = dst;

   Register shifted_src = src;

   if (Universe::narrow_klass_shift() != 0 ||

       Universe::narrow_klass_base() == 0 && src != dst) {  // Move required.

     shifted_src = dst;

     sldi(shifted_src, src, Universe::narrow_klass_shift());

   }

   if (Universe::narrow_klass_base() != 0) {

     load_const(R0, Universe::narrow_klass_base());

     add(dst, shifted_src, R0);

   }

 }

 void MacroAssembler::load_klass(Register dst, Register src) {

   if (UseCompressedClassPointers) {

     lwz(dst, oopDesc::klass_offset_in_bytes(), src);

     // Attention: no null check here!

     decode_klass_not_null(dst, dst);

   } else {

     ld(dst, oopDesc::klass_offset_in_bytes(), src);

   }

 }

 void MacroAssembler::load_klass_with_trap_null_check(Register dst, Register src) {

   if (false  NOT_LINUX(|| true) /*!os::zero_page_read_protected()*/) {

     if (TrapBasedNullChecks) {

       trap_null_check(src);

     }

   }

   load_klass(dst, src);

 }

 void MacroAssembler::reinit_heapbase(Register d, Register tmp) {

   if (Universe::heap() != NULL) {

     if (Universe::narrow_oop_base() == NULL) {

       Assembler::xorr(R30, R30, R30);

     } else {

       load_const(R30, Universe::narrow_ptrs_base(), tmp);

     }

   } else {

     load_const(R30, Universe::narrow_ptrs_base_addr(), tmp);

     ld(R30, 0, R30);

   }

 }

 /////////////////////////////////////////// String intrinsics ////////////////////////////////////////////

 // Search for a single jchar in an jchar[].

 //

 // Assumes that result differs from all other registers.

 //

 // Haystack, needle are the addresses of jchar-arrays.

 // NeedleChar is needle[0] if it is known at compile time.

 // Haycnt is the length of the haystack. We assume haycnt >=1.

 //

 // Preserves haystack, haycnt, kills all other registers.

 //

 // If needle == R0, we search for the constant needleChar.

 void MacroAssembler::string_indexof_1(Register result, Register haystack, Register haycnt,

                                       Register needle, jchar needleChar,

                                       Register tmp1, Register tmp2) {

   assert_different_registers(result, haystack, haycnt, needle, tmp1, tmp2);

   Label L_InnerLoop, L_FinalCheck, L_Found1, L_Found2, L_Found3, L_NotFound, L_End;

   Register needle0 = needle, // Contains needle[0].

            addr = tmp1,

            ch1 = tmp2,

            ch2 = R0;

 //2 (variable) or 3 (const):

    if (needle != R0) lhz(needle0, 0, needle); // Preload needle character, needle has len==1.

    dcbtct(haystack, 0x00);                        // Indicate R/O access to haystack.

    srwi_(tmp2, haycnt, 1);   // Shift right by exact_log2(UNROLL_FACTOR).

    mr(addr, haystack);

    beq(CCR0, L_FinalCheck);

    mtctr(tmp2);              // Move to count register.

 //8:

   bind(L_InnerLoop);             // Main work horse (2x unrolled search loop).

    lhz(ch1, 0, addr);        // Load characters from haystack.

    lhz(ch2, 2, addr);

    (needle != R0) ? cmpw(CCR0, ch1, needle0) : cmplwi(CCR0, ch1, needleChar);

    (needle != R0) ? cmpw(CCR1, ch2, needle0) : cmplwi(CCR1, ch2, needleChar);

    beq(CCR0, L_Found1);   // Did we find the needle?

    beq(CCR1, L_Found2);

    addi(addr, addr, 4);

    bdnz(L_InnerLoop);

 //16:

   bind(L_FinalCheck);

    andi_(R0, haycnt, 1);

    beq(CCR0, L_NotFound);

    lhz(ch1, 0, addr);        // One position left at which we have to compare.

    (needle != R0) ? cmpw(CCR1, ch1, needle0) : cmplwi(CCR1, ch1, needleChar);

    beq(CCR1, L_Found3);

 //21:

   bind(L_NotFound);

    li(result, -1);           // Not found.

    b(L_End);

   bind(L_Found2);

    addi(addr, addr, 2);

 //24:

   bind(L_Found1);

   bind(L_Found3);                  // Return index ...

    subf(addr, haystack, addr); // relative to haystack,

    srdi(result, addr, 1);      // in characters.

   bind(L_End);

 }

 // Implementation of IndexOf for jchar arrays.

 //

 // The length of haystack and needle are not constant, i.e. passed in a register.

 //

 // Preserves registers haystack, needle.

 // Kills registers haycnt, needlecnt.

 // Assumes that result differs from all other registers.

 // Haystack, needle are the addresses of jchar-arrays.

 // Haycnt, needlecnt are the lengths of them, respectively.

 //

 // Needlecntval must be zero or 15-bit unsigned immediate and > 1.

 void MacroAssembler::string_indexof(Register result, Register haystack, Register haycnt,

                                     Register needle, ciTypeArray* needle_values, Register needlecnt, int needlecntval,

                                     Register tmp1, Register tmp2, Register tmp3, Register tmp4) {

   // Ensure 0<needlecnt<=haycnt in ideal graph as prerequisite!

   Label L_TooShort, L_Found, L_NotFound, L_End;

   Register last_addr = haycnt, // Kill haycnt at the beginning.

            addr      = tmp1,

            n_start   = tmp2,

            ch1       = tmp3,

            ch2       = R0;

   // **************************************************************************************************

   // Prepare for main loop: optimized for needle count >=2, bail out otherwise.

   // **************************************************************************************************

 //1 (variable) or 3 (const):

    dcbtct(needle, 0x00);    // Indicate R/O access to str1.

    dcbtct(haystack, 0x00);  // Indicate R/O access to str2.

   // Compute last haystack addr to use if no match gets found.

   if (needlecntval == 0) { // variable needlecnt

 //3:

    subf(ch1, needlecnt, haycnt);      // Last character index to compare is haycnt-needlecnt.

    addi(addr, haystack, -2);          // Accesses use pre-increment.

    cmpwi(CCR6, needlecnt, 2);

    blt(CCR6, L_TooShort);          // Variable needlecnt: handle short needle separately.

    slwi(ch1, ch1, 1);                 // Scale to number of bytes.

    lwz(n_start, 0, needle);           // Load first 2 characters of needle.

    add(last_addr, haystack, ch1);     // Point to last address to compare (haystack+2*(haycnt-needlecnt)).

    addi(needlecnt, needlecnt, -2);    // Rest of needle.

   } else { // constant needlecnt

   guarantee(needlecntval != 1, "IndexOf with single-character needle must be handled separately");

   assert((needlecntval & 0x7fff) == needlecntval, "wrong immediate");

 //5:

    addi(ch1, haycnt, -needlecntval);  // Last character index to compare is haycnt-needlecnt.

    lwz(n_start, 0, needle);           // Load first 2 characters of needle.

    addi(addr, haystack, -2);          // Accesses use pre-increment.

    slwi(ch1, ch1, 1);                 // Scale to number of bytes.

    add(last_addr, haystack, ch1);     // Point to last address to compare (haystack+2*(haycnt-needlecnt)).

    li(needlecnt, needlecntval-2);     // Rest of needle.

   }

   // Main Loop (now we have at least 3 characters).

 //11:

   Label L_OuterLoop, L_InnerLoop, L_FinalCheck, L_Comp1, L_Comp2, L_Comp3;

   bind(L_OuterLoop); // Search for 1st 2 characters.

   Register addr_diff = tmp4;

    subf(addr_diff, addr, last_addr); // Difference between already checked address and last address to check.

    addi(addr, addr, 2);              // This is the new address we want to use for comparing.

    srdi_(ch2, addr_diff, 2);

    beq(CCR0, L_FinalCheck);       // 2 characters left?

    mtctr(ch2);                       // addr_diff/4

 //16:

   bind(L_InnerLoop);                // Main work horse (2x unrolled search loop)

    lwz(ch1, 0, addr);           // Load 2 characters of haystack (ignore alignment).

    lwz(ch2, 2, addr);

    cmpw(CCR0, ch1, n_start); // Compare 2 characters (1 would be sufficient but try to reduce branches to CompLoop).

    cmpw(CCR1, ch2, n_start);

    beq(CCR0, L_Comp1);       // Did we find the needle start?

    beq(CCR1, L_Comp2);

    addi(addr, addr, 4);

    bdnz(L_InnerLoop);

 //24:

   bind(L_FinalCheck);

    rldicl_(addr_diff, addr_diff, 64-1, 63); // Remaining characters not covered by InnerLoop: (addr_diff>>1)&1.

    beq(CCR0, L_NotFound);

    lwz(ch1, 0, addr);                       // One position left at which we have to compare.

    cmpw(CCR1, ch1, n_start);

    beq(CCR1, L_Comp3);

 //29:

   bind(L_NotFound);

    li(result, -1); // not found

    b(L_End);

    // **************************************************************************************************

    // Special Case: unfortunately, the variable needle case can be called with needlecnt<2

    // **************************************************************************************************

 //31:

  if ((needlecntval>>1) !=1 ) { // Const needlecnt is 2 or 3? Reduce code size.

   int nopcnt = 5;

   if (needlecntval !=0 ) ++nopcnt; // Balance alignment (other case: see below).

   if (needlecntval == 0) {         // We have to handle these cases separately.

   Label L_OneCharLoop;

   bind(L_TooShort);

    mtctr(haycnt);

    lhz(n_start, 0, needle);    // First character of needle

   bind(L_OneCharLoop);

    lhzu(ch1, 2, addr);

    cmpw(CCR1, ch1, n_start);

    beq(CCR1, L_Found);      // Did we find the one character needle?

    bdnz(L_OneCharLoop);

    li(result, -1);             // Not found.

    b(L_End);

   } // 8 instructions, so no impact on alignment.

   for (int x = 0; x < nopcnt; ++x) nop();

  }

   // **************************************************************************************************

   // Regular Case Part II: compare rest of needle (first 2 characters have been compared already)

   // **************************************************************************************************

   // Compare the rest

 //36 if needlecntval==0, else 37:

   bind(L_Comp2);

    addi(addr, addr, 2); // First comparison has failed, 2nd one hit.

   bind(L_Comp1);            // Addr points to possible needle start.

   bind(L_Comp3);            // Could have created a copy and use a different return address but saving code size here.

   if (needlecntval != 2) {  // Const needlecnt==2?

    if (needlecntval != 3) {

     if (needlecntval == 0) beq(CCR6, L_Found); // Variable needlecnt==2?