AArch64: Added arm64 quick backend as an arm clone.

Created a new directory arm64 under compiler/dex/quick which contains
a copy of the 32-bit arm backend.  In following CLs, this code will
be replaced/modified to support Aarch64.

Change-Id: I06c468db8d588e339eecf4d7d85276d5e334a17a
diff --git a/compiler/dex/quick/arm64/call_arm64.cc b/compiler/dex/quick/arm64/call_arm64.cc
new file mode 100644
index 0000000..9dfee6e
--- /dev/null
+++ b/compiler/dex/quick/arm64/call_arm64.cc
@@ -0,0 +1,477 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* This file contains codegen for the Thumb2 ISA. */
+
+#include "arm64_lir.h"
+#include "codegen_arm64.h"
+#include "dex/quick/mir_to_lir-inl.h"
+#include "entrypoints/quick/quick_entrypoints.h"
+
+namespace art {
+
+/*
+ * The sparse table in the literal pool is an array of <key,displacement>
+ * pairs.  For each set, we'll load them as a pair using ldmia.
+ * This means that the register number of the temp we use for the key
+ * must be lower than the reg for the displacement.
+ *
+ * The test loop will look something like:
+ *
+ *   adr   r_base, <table>
+ *   ldr   r_val, [rARM_SP, v_reg_off]
+ *   mov   r_idx, #table_size
+ * lp:
+ *   ldmia r_base!, {r_key, r_disp}
+ *   sub   r_idx, #1
+ *   cmp   r_val, r_key
+ *   ifeq
+ *   add   rARM_PC, r_disp   ; This is the branch from which we compute displacement
+ *   cbnz  r_idx, lp
+ */
+void Arm64Mir2Lir::GenSparseSwitch(MIR* mir, uint32_t table_offset,
+                                 RegLocation rl_src) {
+  const uint16_t* table = cu_->insns + current_dalvik_offset_ + table_offset;
+  if (cu_->verbose) {
+    DumpSparseSwitchTable(table);
+  }
+  // Add the table to the list - we'll process it later
+  SwitchTable *tab_rec =
+      static_cast<SwitchTable*>(arena_->Alloc(sizeof(SwitchTable), kArenaAllocData));
+  tab_rec->table = table;
+  tab_rec->vaddr = current_dalvik_offset_;
+  uint32_t size = table[1];
+  tab_rec->targets = static_cast<LIR**>(arena_->Alloc(size * sizeof(LIR*), kArenaAllocLIR));
+  switch_tables_.Insert(tab_rec);
+
+  // Get the switch value
+  rl_src = LoadValue(rl_src, kCoreReg);
+  RegStorage r_base = AllocTemp();
+  /* Allocate key and disp temps */
+  RegStorage r_key = AllocTemp();
+  RegStorage r_disp = AllocTemp();
+  // Make sure r_key's register number is less than r_disp's number for ldmia
+  if (r_key.GetReg() > r_disp.GetReg()) {
+    RegStorage tmp = r_disp;
+    r_disp = r_key;
+    r_key = tmp;
+  }
+  // Materialize a pointer to the switch table
+  NewLIR3(kThumb2Adr, r_base.GetReg(), 0, WrapPointer(tab_rec));
+  // Set up r_idx
+  RegStorage r_idx = AllocTemp();
+  LoadConstant(r_idx, size);
+  // Establish loop branch target
+  LIR* target = NewLIR0(kPseudoTargetLabel);
+  // Load next key/disp
+  NewLIR2(kThumb2LdmiaWB, r_base.GetReg(), (1 << r_key.GetRegNum()) | (1 << r_disp.GetRegNum()));
+  OpRegReg(kOpCmp, r_key, rl_src.reg);
+  // Go if match. NOTE: No instruction set switch here - must stay Thumb2
+  LIR* it = OpIT(kCondEq, "");
+  LIR* switch_branch = NewLIR1(kThumb2AddPCR, r_disp.GetReg());
+  OpEndIT(it);
+  tab_rec->anchor = switch_branch;
+  // Needs to use setflags encoding here
+  OpRegRegImm(kOpSub, r_idx, r_idx, 1);  // For value == 1, this should set flags.
+  DCHECK(last_lir_insn_->u.m.def_mask & ENCODE_CCODE);
+  OpCondBranch(kCondNe, target);
+}
+
+
+void Arm64Mir2Lir::GenPackedSwitch(MIR* mir, uint32_t table_offset,
+                                 RegLocation rl_src) {
+  const uint16_t* table = cu_->insns + current_dalvik_offset_ + table_offset;
+  if (cu_->verbose) {
+    DumpPackedSwitchTable(table);
+  }
+  // Add the table to the list - we'll process it later
+  SwitchTable *tab_rec =
+      static_cast<SwitchTable*>(arena_->Alloc(sizeof(SwitchTable),  kArenaAllocData));
+  tab_rec->table = table;
+  tab_rec->vaddr = current_dalvik_offset_;
+  uint32_t size = table[1];
+  tab_rec->targets =
+      static_cast<LIR**>(arena_->Alloc(size * sizeof(LIR*), kArenaAllocLIR));
+  switch_tables_.Insert(tab_rec);
+
+  // Get the switch value
+  rl_src = LoadValue(rl_src, kCoreReg);
+  RegStorage table_base = AllocTemp();
+  // Materialize a pointer to the switch table
+  NewLIR3(kThumb2Adr, table_base.GetReg(), 0, WrapPointer(tab_rec));
+  int low_key = s4FromSwitchData(&table[2]);
+  RegStorage keyReg;
+  // Remove the bias, if necessary
+  if (low_key == 0) {
+    keyReg = rl_src.reg;
+  } else {
+    keyReg = AllocTemp();
+    OpRegRegImm(kOpSub, keyReg, rl_src.reg, low_key);
+  }
+  // Bounds check - if < 0 or >= size continue following switch
+  OpRegImm(kOpCmp, keyReg, size-1);
+  LIR* branch_over = OpCondBranch(kCondHi, NULL);
+
+  // Load the displacement from the switch table
+  RegStorage disp_reg = AllocTemp();
+  LoadBaseIndexed(table_base, keyReg, disp_reg, 2, k32);
+
+  // ..and go! NOTE: No instruction set switch here - must stay Thumb2
+  LIR* switch_branch = NewLIR1(kThumb2AddPCR, disp_reg.GetReg());
+  tab_rec->anchor = switch_branch;
+
+  /* branch_over target here */
+  LIR* target = NewLIR0(kPseudoTargetLabel);
+  branch_over->target = target;
+}
+
+/*
+ * Array data table format:
+ *  ushort ident = 0x0300   magic value
+ *  ushort width            width of each element in the table
+ *  uint   size             number of elements in the table
+ *  ubyte  data[size*width] table of data values (may contain a single-byte
+ *                          padding at the end)
+ *
+ * Total size is 4+(width * size + 1)/2 16-bit code units.
+ */
+void Arm64Mir2Lir::GenFillArrayData(uint32_t table_offset, RegLocation rl_src) {
+  const uint16_t* table = cu_->insns + current_dalvik_offset_ + table_offset;
+  // Add the table to the list - we'll process it later
+  FillArrayData *tab_rec =
+      static_cast<FillArrayData*>(arena_->Alloc(sizeof(FillArrayData), kArenaAllocData));
+  tab_rec->table = table;
+  tab_rec->vaddr = current_dalvik_offset_;
+  uint16_t width = tab_rec->table[1];
+  uint32_t size = tab_rec->table[2] | ((static_cast<uint32_t>(tab_rec->table[3])) << 16);
+  tab_rec->size = (size * width) + 8;
+
+  fill_array_data_.Insert(tab_rec);
+
+  // Making a call - use explicit registers
+  FlushAllRegs();   /* Everything to home location */
+  LoadValueDirectFixed(rl_src, rs_r0);
+  LoadWordDisp(rs_rARM_SELF, QUICK_ENTRYPOINT_OFFSET(4, pHandleFillArrayData).Int32Value(),
+               rs_rARM_LR);
+  // Materialize a pointer to the fill data image
+  NewLIR3(kThumb2Adr, rs_r1.GetReg(), 0, WrapPointer(tab_rec));
+  ClobberCallerSave();
+  LIR* call_inst = OpReg(kOpBlx, rs_rARM_LR);
+  MarkSafepointPC(call_inst);
+}
+
+/*
+ * Handle unlocked -> thin locked transition inline or else call out to quick entrypoint. For more
+ * details see monitor.cc.
+ */
+void Arm64Mir2Lir::GenMonitorEnter(int opt_flags, RegLocation rl_src) {
+  FlushAllRegs();
+  // FIXME: need separate LoadValues for object references.
+  LoadValueDirectFixed(rl_src, rs_r0);  // Get obj
+  LockCallTemps();  // Prepare for explicit register usage
+  constexpr bool kArchVariantHasGoodBranchPredictor = false;  // TODO: true if cortex-A15.
+  if (kArchVariantHasGoodBranchPredictor) {
+    LIR* null_check_branch = nullptr;
+    if ((opt_flags & MIR_IGNORE_NULL_CHECK) && !(cu_->disable_opt & (1 << kNullCheckElimination))) {
+      null_check_branch = nullptr;  // No null check.
+    } else {
+      // If the null-check fails its handled by the slow-path to reduce exception related meta-data.
+      if (Runtime::Current()->ExplicitNullChecks()) {
+        null_check_branch = OpCmpImmBranch(kCondEq, rs_r0, 0, NULL);
+      }
+    }
+    Load32Disp(rs_rARM_SELF, Thread::ThinLockIdOffset<4>().Int32Value(), rs_r2);
+    NewLIR3(kThumb2Ldrex, rs_r1.GetReg(), rs_r0.GetReg(),
+        mirror::Object::MonitorOffset().Int32Value() >> 2);
+    MarkPossibleNullPointerException(opt_flags);
+    LIR* not_unlocked_branch = OpCmpImmBranch(kCondNe, rs_r1, 0, NULL);
+    NewLIR4(kThumb2Strex, rs_r1.GetReg(), rs_r2.GetReg(), rs_r0.GetReg(),
+        mirror::Object::MonitorOffset().Int32Value() >> 2);
+    LIR* lock_success_branch = OpCmpImmBranch(kCondEq, rs_r1, 0, NULL);
+
+
+    LIR* slow_path_target = NewLIR0(kPseudoTargetLabel);
+    not_unlocked_branch->target = slow_path_target;
+    if (null_check_branch != nullptr) {
+      null_check_branch->target = slow_path_target;
+    }
+    // TODO: move to a slow path.
+    // Go expensive route - artLockObjectFromCode(obj);
+    LoadWordDisp(rs_rARM_SELF, QUICK_ENTRYPOINT_OFFSET(4, pLockObject).Int32Value(), rs_rARM_LR);
+    ClobberCallerSave();
+    LIR* call_inst = OpReg(kOpBlx, rs_rARM_LR);
+    MarkSafepointPC(call_inst);
+
+    LIR* success_target = NewLIR0(kPseudoTargetLabel);
+    lock_success_branch->target = success_target;
+    GenMemBarrier(kLoadLoad);
+  } else {
+    // Explicit null-check as slow-path is entered using an IT.
+    GenNullCheck(rs_r0, opt_flags);
+    Load32Disp(rs_rARM_SELF, Thread::ThinLockIdOffset<4>().Int32Value(), rs_r2);
+    NewLIR3(kThumb2Ldrex, rs_r1.GetReg(), rs_r0.GetReg(),
+        mirror::Object::MonitorOffset().Int32Value() >> 2);
+    MarkPossibleNullPointerException(opt_flags);
+    OpRegImm(kOpCmp, rs_r1, 0);
+    LIR* it = OpIT(kCondEq, "");
+    NewLIR4(kThumb2Strex/*eq*/, rs_r1.GetReg(), rs_r2.GetReg(), rs_r0.GetReg(),
+        mirror::Object::MonitorOffset().Int32Value() >> 2);
+    OpEndIT(it);
+    OpRegImm(kOpCmp, rs_r1, 0);
+    it = OpIT(kCondNe, "T");
+    // Go expensive route - artLockObjectFromCode(self, obj);
+    LoadWordDisp/*ne*/(rs_rARM_SELF, QUICK_ENTRYPOINT_OFFSET(4, pLockObject).Int32Value(),
+                       rs_rARM_LR);
+    ClobberCallerSave();
+    LIR* call_inst = OpReg(kOpBlx/*ne*/, rs_rARM_LR);
+    OpEndIT(it);
+    MarkSafepointPC(call_inst);
+    GenMemBarrier(kLoadLoad);
+  }
+}
+
+/*
+ * Handle thin locked -> unlocked transition inline or else call out to quick entrypoint. For more
+ * details see monitor.cc. Note the code below doesn't use ldrex/strex as the code holds the lock
+ * and can only give away ownership if its suspended.
+ */
+void Arm64Mir2Lir::GenMonitorExit(int opt_flags, RegLocation rl_src) {
+  FlushAllRegs();
+  LoadValueDirectFixed(rl_src, rs_r0);  // Get obj
+  LockCallTemps();  // Prepare for explicit register usage
+  LIR* null_check_branch = nullptr;
+  Load32Disp(rs_rARM_SELF, Thread::ThinLockIdOffset<4>().Int32Value(), rs_r2);
+  constexpr bool kArchVariantHasGoodBranchPredictor = false;  // TODO: true if cortex-A15.
+  if (kArchVariantHasGoodBranchPredictor) {
+    if ((opt_flags & MIR_IGNORE_NULL_CHECK) && !(cu_->disable_opt & (1 << kNullCheckElimination))) {
+      null_check_branch = nullptr;  // No null check.
+    } else {
+      // If the null-check fails its handled by the slow-path to reduce exception related meta-data.
+      if (Runtime::Current()->ExplicitNullChecks()) {
+        null_check_branch = OpCmpImmBranch(kCondEq, rs_r0, 0, NULL);
+      }
+    }
+    Load32Disp(rs_r0, mirror::Object::MonitorOffset().Int32Value(), rs_r1);
+    MarkPossibleNullPointerException(opt_flags);
+    LoadConstantNoClobber(rs_r3, 0);
+    LIR* slow_unlock_branch = OpCmpBranch(kCondNe, rs_r1, rs_r2, NULL);
+    Store32Disp(rs_r0, mirror::Object::MonitorOffset().Int32Value(), rs_r3);
+    LIR* unlock_success_branch = OpUnconditionalBranch(NULL);
+
+    LIR* slow_path_target = NewLIR0(kPseudoTargetLabel);
+    slow_unlock_branch->target = slow_path_target;
+    if (null_check_branch != nullptr) {
+      null_check_branch->target = slow_path_target;
+    }
+    // TODO: move to a slow path.
+    // Go expensive route - artUnlockObjectFromCode(obj);
+    LoadWordDisp(rs_rARM_SELF, QUICK_ENTRYPOINT_OFFSET(4, pUnlockObject).Int32Value(), rs_rARM_LR);
+    ClobberCallerSave();
+    LIR* call_inst = OpReg(kOpBlx, rs_rARM_LR);
+    MarkSafepointPC(call_inst);
+
+    LIR* success_target = NewLIR0(kPseudoTargetLabel);
+    unlock_success_branch->target = success_target;
+    GenMemBarrier(kStoreLoad);
+  } else {
+    // Explicit null-check as slow-path is entered using an IT.
+    GenNullCheck(rs_r0, opt_flags);
+    Load32Disp(rs_r0, mirror::Object::MonitorOffset().Int32Value(), rs_r1);  // Get lock
+    MarkPossibleNullPointerException(opt_flags);
+    Load32Disp(rs_rARM_SELF, Thread::ThinLockIdOffset<4>().Int32Value(), rs_r2);
+    LoadConstantNoClobber(rs_r3, 0);
+    // Is lock unheld on lock or held by us (==thread_id) on unlock?
+    OpRegReg(kOpCmp, rs_r1, rs_r2);
+    LIR* it = OpIT(kCondEq, "EE");
+    Store32Disp/*eq*/(rs_r0, mirror::Object::MonitorOffset().Int32Value(), rs_r3);
+    // Go expensive route - UnlockObjectFromCode(obj);
+    LoadWordDisp/*ne*/(rs_rARM_SELF, QUICK_ENTRYPOINT_OFFSET(4, pUnlockObject).Int32Value(),
+                       rs_rARM_LR);
+    ClobberCallerSave();
+    LIR* call_inst = OpReg(kOpBlx/*ne*/, rs_rARM_LR);
+    OpEndIT(it);
+    MarkSafepointPC(call_inst);
+    GenMemBarrier(kStoreLoad);
+  }
+}
+
+void Arm64Mir2Lir::GenMoveException(RegLocation rl_dest) {
+  int ex_offset = Thread::ExceptionOffset<4>().Int32Value();
+  RegLocation rl_result = EvalLoc(rl_dest, kCoreReg, true);
+  RegStorage reset_reg = AllocTemp();
+  Load32Disp(rs_rARM_SELF, ex_offset, rl_result.reg);
+  LoadConstant(reset_reg, 0);
+  Store32Disp(rs_rARM_SELF, ex_offset, reset_reg);
+  FreeTemp(reset_reg);
+  StoreValue(rl_dest, rl_result);
+}
+
+/*
+ * Mark garbage collection card. Skip if the value we're storing is null.
+ */
+void Arm64Mir2Lir::MarkGCCard(RegStorage val_reg, RegStorage tgt_addr_reg) {
+  RegStorage reg_card_base = AllocTemp();
+  RegStorage reg_card_no = AllocTemp();
+  LIR* branch_over = OpCmpImmBranch(kCondEq, val_reg, 0, NULL);
+  LoadWordDisp(rs_rARM_SELF, Thread::CardTableOffset<4>().Int32Value(), reg_card_base);
+  OpRegRegImm(kOpLsr, reg_card_no, tgt_addr_reg, gc::accounting::CardTable::kCardShift);
+  StoreBaseIndexed(reg_card_base, reg_card_no, reg_card_base, 0, kUnsignedByte);
+  LIR* target = NewLIR0(kPseudoTargetLabel);
+  branch_over->target = target;
+  FreeTemp(reg_card_base);
+  FreeTemp(reg_card_no);
+}
+
+void Arm64Mir2Lir::GenEntrySequence(RegLocation* ArgLocs, RegLocation rl_method) {
+  int spill_count = num_core_spills_ + num_fp_spills_;
+  /*
+   * On entry, r0, r1, r2 & r3 are live.  Let the register allocation
+   * mechanism know so it doesn't try to use any of them when
+   * expanding the frame or flushing.  This leaves the utility
+   * code with a single temp: r12.  This should be enough.
+   */
+  LockTemp(rs_r0);
+  LockTemp(rs_r1);
+  LockTemp(rs_r2);
+  LockTemp(rs_r3);
+
+  /*
+   * We can safely skip the stack overflow check if we're
+   * a leaf *and* our frame size < fudge factor.
+   */
+  bool skip_overflow_check = (mir_graph_->MethodIsLeaf() &&
+                            (static_cast<size_t>(frame_size_) <
+                            Thread::kStackOverflowReservedBytes));
+  NewLIR0(kPseudoMethodEntry);
+  if (!skip_overflow_check) {
+    if (Runtime::Current()->ExplicitStackOverflowChecks()) {
+      /* Load stack limit */
+      Load32Disp(rs_rARM_SELF, Thread::StackEndOffset<4>().Int32Value(), rs_r12);
+    }
+  }
+  /* Spill core callee saves */
+  NewLIR1(kThumb2Push, core_spill_mask_);
+  /* Need to spill any FP regs? */
+  if (num_fp_spills_) {
+    /*
+     * NOTE: fp spills are a little different from core spills in that
+     * they are pushed as a contiguous block.  When promoting from
+     * the fp set, we must allocate all singles from s16..highest-promoted
+     */
+    NewLIR1(kThumb2VPushCS, num_fp_spills_);
+  }
+
+  const int spill_size = spill_count * 4;
+  const int frame_size_without_spills = frame_size_ - spill_size;
+  if (!skip_overflow_check) {
+    if (Runtime::Current()->ExplicitStackOverflowChecks()) {
+      class StackOverflowSlowPath : public LIRSlowPath {
+       public:
+        StackOverflowSlowPath(Mir2Lir* m2l, LIR* branch, bool restore_lr, size_t sp_displace)
+            : LIRSlowPath(m2l, m2l->GetCurrentDexPc(), branch, nullptr), restore_lr_(restore_lr),
+              sp_displace_(sp_displace) {
+        }
+        void Compile() OVERRIDE {
+          m2l_->ResetRegPool();
+          m2l_->ResetDefTracking();
+          GenerateTargetLabel(kPseudoThrowTarget);
+          if (restore_lr_) {
+            m2l_->LoadWordDisp(rs_rARM_SP, sp_displace_ - 4, rs_rARM_LR);
+          }
+          m2l_->OpRegImm(kOpAdd, rs_rARM_SP, sp_displace_);
+          m2l_->ClobberCallerSave();
+          ThreadOffset<4> func_offset = QUICK_ENTRYPOINT_OFFSET(4, pThrowStackOverflow);
+          // Load the entrypoint directly into the pc instead of doing a load + branch. Assumes
+          // codegen and target are in thumb2 mode.
+          // NOTE: native pointer.
+          m2l_->LoadWordDisp(rs_rARM_SELF, func_offset.Int32Value(), rs_rARM_PC);
+        }
+
+       private:
+        const bool restore_lr_;
+        const size_t sp_displace_;
+      };
+      if (static_cast<size_t>(frame_size_) > Thread::kStackOverflowReservedUsableBytes) {
+        OpRegRegImm(kOpSub, rs_rARM_LR, rs_rARM_SP, frame_size_without_spills);
+        LIR* branch = OpCmpBranch(kCondUlt, rs_rARM_LR, rs_r12, nullptr);
+        // Need to restore LR since we used it as a temp.
+        AddSlowPath(new(arena_)StackOverflowSlowPath(this, branch, true, spill_size));
+        OpRegCopy(rs_rARM_SP, rs_rARM_LR);     // Establish stack
+      } else {
+        // If the frame is small enough we are guaranteed to have enough space that remains to
+        // handle signals on the user stack.
+        OpRegRegImm(kOpSub, rs_rARM_SP, rs_rARM_SP, frame_size_without_spills);
+        LIR* branch = OpCmpBranch(kCondUlt, rs_rARM_SP, rs_r12, nullptr);
+        AddSlowPath(new(arena_)StackOverflowSlowPath(this, branch, false, frame_size_));
+      }
+    } else {
+      // Implicit stack overflow check.
+      // Generate a load from [sp, #-overflowsize].  If this is in the stack
+      // redzone we will get a segmentation fault.
+      //
+      // Caveat coder: if someone changes the kStackOverflowReservedBytes value
+      // we need to make sure that it's loadable in an immediate field of
+      // a sub instruction.  Otherwise we will get a temp allocation and the
+      // code size will increase.
+      OpRegRegImm(kOpSub, rs_r12, rs_rARM_SP, Thread::kStackOverflowReservedBytes);
+      Load32Disp(rs_r12, 0, rs_r12);
+      MarkPossibleStackOverflowException();
+      OpRegImm(kOpSub, rs_rARM_SP, frame_size_without_spills);
+    }
+  } else {
+    OpRegImm(kOpSub, rs_rARM_SP, frame_size_without_spills);
+  }
+
+  FlushIns(ArgLocs, rl_method);
+
+  FreeTemp(rs_r0);
+  FreeTemp(rs_r1);
+  FreeTemp(rs_r2);
+  FreeTemp(rs_r3);
+}
+
+void Arm64Mir2Lir::GenExitSequence() {
+  int spill_count = num_core_spills_ + num_fp_spills_;
+  /*
+   * In the exit path, r0/r1 are live - make sure they aren't
+   * allocated by the register utilities as temps.
+   */
+  LockTemp(rs_r0);
+  LockTemp(rs_r1);
+
+  NewLIR0(kPseudoMethodExit);
+  OpRegImm(kOpAdd, rs_rARM_SP, frame_size_ - (spill_count * 4));
+  /* Need to restore any FP callee saves? */
+  if (num_fp_spills_) {
+    NewLIR1(kThumb2VPopCS, num_fp_spills_);
+  }
+  if (core_spill_mask_ & (1 << rs_rARM_LR.GetRegNum())) {
+    /* Unspill rARM_LR to rARM_PC */
+    core_spill_mask_ &= ~(1 << rs_rARM_LR.GetRegNum());
+    core_spill_mask_ |= (1 << rs_rARM_PC.GetRegNum());
+  }
+  NewLIR1(kThumb2Pop, core_spill_mask_);
+  if (!(core_spill_mask_ & (1 << rs_rARM_PC.GetRegNum()))) {
+    /* We didn't pop to rARM_PC, so must do a bv rARM_LR */
+    NewLIR1(kThumbBx, rs_rARM_LR.GetReg());
+  }
+}
+
+void Arm64Mir2Lir::GenSpecialExitSequence() {
+  NewLIR1(kThumbBx, rs_rARM_LR.GetReg());
+}
+
+}  // namespace art