src/oat/jni/jni_compiler.cc

/*
 * 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.
 */

#include <sys/mman.h>
#include <vector>

#include "calling_convention.h"
#include "class_linker.h"
#include "compiled_method.h"
#include "compiler.h"
#include "disassembler.h"
#include "jni_internal.h"
#include "logging.h"
#include "macros.h"
#include "oat/runtime/oat_support_entrypoints.h"
#include "oat/utils/assembler.h"
#include "oat/utils/managed_register.h"
#include "oat/utils/arm/managed_register_arm.h"
#include "oat/utils/x86/managed_register_x86.h"
#include "thread.h"
#include "UniquePtr.h"

#define __ jni_asm->

namespace art {

static void ChangeThreadState(Assembler* jni_asm, ThreadState new_state,
                              ManagedRegister scratch, ManagedRegister return_reg,
                              FrameOffset return_save_location,
                              size_t return_size) {
  /*
   * This code mirrors that of Thread::SetState where detail is given on why
   * barriers occur when they do.
   */
  if (new_state == kRunnable) {
    /*
     * Change our status to kRunnable.  The transition requires
     * that we check for pending suspension, because the runtime considers
     * us to be "asleep" in all other states, and another thread could
     * be performing a GC now.
     */
    __ StoreImmediateToThread(Thread::StateOffset(), kRunnable, scratch);
    __ MemoryBarrier(scratch);
    __ SuspendPoll(scratch, return_reg, return_save_location, return_size);
  } else {
    /*
     * Not changing to kRunnable. No additional work required.
     */
    __ MemoryBarrier(scratch);
    __ StoreImmediateToThread(Thread::StateOffset(), new_state, scratch);
  }
}

// Copy a single parameter from the managed to the JNI calling convention
static void CopyParameter(Assembler* jni_asm,
                          ManagedRuntimeCallingConvention* mr_conv,
                          JniCallingConvention* jni_conv,
                          size_t frame_size, size_t out_arg_size) {
  bool input_in_reg = mr_conv->IsCurrentParamInRegister();
  bool output_in_reg = jni_conv->IsCurrentParamInRegister();
  FrameOffset sirt_offset(0);
  bool null_allowed = false;
  bool ref_param = jni_conv->IsCurrentParamAReference();
  CHECK(!ref_param || mr_conv->IsCurrentParamAReference());
  // input may be in register, on stack or both - but not none!
  CHECK(input_in_reg || mr_conv->IsCurrentParamOnStack());
  if (output_in_reg) {  // output shouldn't straddle registers and stack
    CHECK(!jni_conv->IsCurrentParamOnStack());
  } else {
    CHECK(jni_conv->IsCurrentParamOnStack());
  }
  // References need placing in SIRT and the entry address passing
  if (ref_param) {
    null_allowed = mr_conv->IsCurrentArgPossiblyNull();
    // Compute SIRT offset. Note null is placed in the SIRT but the jobject
    // passed to the native code must be null (not a pointer into the SIRT
    // as with regular references).
    sirt_offset = jni_conv->CurrentParamSirtEntryOffset();
    // Check SIRT offset is within frame.
    CHECK_LT(sirt_offset.Uint32Value(), (frame_size + out_arg_size));
  }
  if (input_in_reg && output_in_reg) {
    ManagedRegister in_reg = mr_conv->CurrentParamRegister();
    ManagedRegister out_reg = jni_conv->CurrentParamRegister();
    if (ref_param) {
      __ CreateSirtEntry(out_reg, sirt_offset, in_reg, null_allowed);
    } else {
      if (!mr_conv->IsCurrentParamOnStack()) {
        // regular non-straddling move
        __ Move(out_reg, in_reg, mr_conv->CurrentParamSize());
      } else {
        UNIMPLEMENTED(FATAL);  // we currently don't expect to see this case
      }
    }
  } else if (!input_in_reg && !output_in_reg) {
    FrameOffset out_off = jni_conv->CurrentParamStackOffset();
    if (ref_param) {
      __ CreateSirtEntry(out_off, sirt_offset, mr_conv->InterproceduralScratchRegister(),
                         null_allowed);
    } else {
      FrameOffset in_off = mr_conv->CurrentParamStackOffset();
      size_t param_size = mr_conv->CurrentParamSize();
      CHECK_EQ(param_size, jni_conv->CurrentParamSize());
      __ Copy(out_off, in_off, mr_conv->InterproceduralScratchRegister(), param_size);
    }
  } else if (!input_in_reg && output_in_reg) {
    FrameOffset in_off = mr_conv->CurrentParamStackOffset();
    ManagedRegister out_reg = jni_conv->CurrentParamRegister();
    // Check that incoming stack arguments are above the current stack frame.
    CHECK_GT(in_off.Uint32Value(), frame_size);
    if (ref_param) {
      __ CreateSirtEntry(out_reg, sirt_offset, ManagedRegister::NoRegister(), null_allowed);
    } else {
      size_t param_size = mr_conv->CurrentParamSize();
      CHECK_EQ(param_size, jni_conv->CurrentParamSize());
      __ Load(out_reg, in_off, param_size);
    }
  } else {
    CHECK(input_in_reg && !output_in_reg);
    ManagedRegister in_reg = mr_conv->CurrentParamRegister();
    FrameOffset out_off = jni_conv->CurrentParamStackOffset();
    // Check outgoing argument is within frame
    CHECK_LT(out_off.Uint32Value(), frame_size);
    if (ref_param) {
      // TODO: recycle value in in_reg rather than reload from SIRT
      __ CreateSirtEntry(out_off, sirt_offset, mr_conv->InterproceduralScratchRegister(),
                         null_allowed);
    } else {
      size_t param_size = mr_conv->CurrentParamSize();
      CHECK_EQ(param_size, jni_conv->CurrentParamSize());
      if (!mr_conv->IsCurrentParamOnStack()) {
        // regular non-straddling store
        __ Store(out_off, in_reg, param_size);
      } else {
        // store where input straddles registers and stack
        CHECK_EQ(param_size, 8u);
        FrameOffset in_off = mr_conv->CurrentParamStackOffset();
        __ StoreSpanning(out_off, in_reg, in_off, mr_conv->InterproceduralScratchRegister());
      }
    }
  }
}

static void SetNativeParameter(Assembler* jni_asm,
                               JniCallingConvention* jni_conv,
                               ManagedRegister in_reg) {
  if (jni_conv->IsCurrentParamOnStack()) {
    FrameOffset dest = jni_conv->CurrentParamStackOffset();
    __ StoreRawPtr(dest, in_reg);
  } else {
    if (!jni_conv->CurrentParamRegister().Equals(in_reg)) {
      __ Move(jni_conv->CurrentParamRegister(), in_reg, jni_conv->CurrentParamSize());
    }
  }
}

static bool IsRegisterPair(InstructionSet instruction_set, ManagedRegister r) {
  return ((instruction_set == kArm && r.AsArm().IsRegisterPair()) ||
          (instruction_set == kX86 && r.AsX86().IsRegisterPair()));
}

// Generate the JNI bridge for the given method, general contract:
// - Arguments are in the managed runtime format, either on stack or in
//   registers, a reference to the method object is supplied as part of this
//   convention.
//
CompiledMethod* ArtJniCompileMethodInternal(Compiler& compiler,
                                            uint32_t access_flags, uint32_t method_idx,
                                            const DexFile& dex_file) {
  CHECK((access_flags & kAccNative) != 0);
  const bool is_static = (access_flags & kAccStatic) != 0;
  const bool is_synchronized = (access_flags & kAccSynchronized) != 0;
  const char* shorty = dex_file.GetMethodShorty(dex_file.GetMethodId(method_idx));
  InstructionSet instruction_set = compiler.GetInstructionSet();
  if (instruction_set == kThumb2) {
    instruction_set = kArm;
  }
  // Calling conventions used to iterate over parameters to method
  UniquePtr<JniCallingConvention> jni_conv(
      JniCallingConvention::Create(is_static, is_synchronized, shorty, instruction_set));
  UniquePtr<ManagedRuntimeCallingConvention> mr_conv(
      ManagedRuntimeCallingConvention::Create(is_static, is_synchronized, shorty, instruction_set));

  // Assembler that holds generated instructions
  UniquePtr<Assembler> jni_asm(Assembler::Create(instruction_set));
  bool should_disassemble = false;

  // Offsets into data structures
  // TODO: if cross compiling these offsets are for the host not the target
  const Offset functions(OFFSETOF_MEMBER(JNIEnvExt, functions));
  const Offset monitor_enter(OFFSETOF_MEMBER(JNINativeInterface, MonitorEnter));
  const Offset monitor_exit(OFFSETOF_MEMBER(JNINativeInterface, MonitorExit));

  // 1. Build the frame saving all callee saves
  const size_t frame_size(jni_conv->FrameSize());
  const std::vector<ManagedRegister>& callee_save_regs = jni_conv->CalleeSaveRegisters();
  __ BuildFrame(frame_size, mr_conv->MethodRegister(), callee_save_regs, mr_conv->EntrySpills());

  // 2. Set up the StackIndirectReferenceTable
  mr_conv->ResetIterator(FrameOffset(frame_size));
  jni_conv->ResetIterator(FrameOffset(0));
  __ StoreImmediateToFrame(jni_conv->SirtNumRefsOffset(),
                           jni_conv->ReferenceCount(),
                           mr_conv->InterproceduralScratchRegister());
  __ CopyRawPtrFromThread(jni_conv->SirtLinkOffset(),
                          Thread::TopSirtOffset(),
                          mr_conv->InterproceduralScratchRegister());
  __ StoreStackOffsetToThread(Thread::TopSirtOffset(),
                              jni_conv->SirtOffset(),
                              mr_conv->InterproceduralScratchRegister());

  // 3. Place incoming reference arguments into SIRT
  jni_conv->Next();  // Skip JNIEnv*
  // 3.5. Create Class argument for static methods out of passed method
  if (is_static) {
    FrameOffset sirt_offset = jni_conv->CurrentParamSirtEntryOffset();
    // Check sirt offset is within frame
    CHECK_LT(sirt_offset.Uint32Value(), frame_size);
    __ LoadRef(jni_conv->InterproceduralScratchRegister(),
               mr_conv->MethodRegister(), Method::DeclaringClassOffset());
    __ VerifyObject(jni_conv->InterproceduralScratchRegister(), false);
    __ StoreRef(sirt_offset, jni_conv->InterproceduralScratchRegister());
    jni_conv->Next();  // in SIRT so move to next argument
  }
  while (mr_conv->HasNext()) {
    CHECK(jni_conv->HasNext());
    bool ref_param = jni_conv->IsCurrentParamAReference();
    CHECK(!ref_param || mr_conv->IsCurrentParamAReference());
    // References need placing in SIRT and the entry value passing
    if (ref_param) {
      // Compute SIRT entry, note null is placed in the SIRT but its boxed value
      // must be NULL
      FrameOffset sirt_offset = jni_conv->CurrentParamSirtEntryOffset();
      // Check SIRT offset is within frame and doesn't run into the saved segment state
      CHECK_LT(sirt_offset.Uint32Value(), frame_size);
      CHECK_NE(sirt_offset.Uint32Value(),
               jni_conv->SavedLocalReferenceCookieOffset().Uint32Value());
      bool input_in_reg = mr_conv->IsCurrentParamInRegister();
      bool input_on_stack = mr_conv->IsCurrentParamOnStack();
      CHECK(input_in_reg || input_on_stack);

      if (input_in_reg) {
        ManagedRegister in_reg  =  mr_conv->CurrentParamRegister();
        __ VerifyObject(in_reg, mr_conv->IsCurrentArgPossiblyNull());
        __ StoreRef(sirt_offset, in_reg);
      } else if (input_on_stack) {
        FrameOffset in_off  = mr_conv->CurrentParamStackOffset();
        __ VerifyObject(in_off, mr_conv->IsCurrentArgPossiblyNull());
        __ CopyRef(sirt_offset, in_off,
                   mr_conv->InterproceduralScratchRegister());
      }
    }
    mr_conv->Next();
    jni_conv->Next();
  }

  // 4. Transition from being in managed to native code. Save the top_of_managed_stack_
  // so that the managed stack can be crawled while in native code. Clear the corresponding
  // PC value that has no meaning for the this frame.
  __ StoreStackPointerToThread(Thread::TopOfManagedStackOffset());
  __ StoreImmediateToThread(Thread::TopOfManagedStackPcOffset(), 0,
                            mr_conv->InterproceduralScratchRegister());
  ChangeThreadState(jni_asm.get(), kNative,
                    mr_conv->InterproceduralScratchRegister(),
                    ManagedRegister::NoRegister(), FrameOffset(0), 0);

  // 5. Move frame down to allow space for out going args. Do for as short a
  //    time as possible to aid profiling..
  const size_t out_arg_size = jni_conv->OutArgSize();
  __ IncreaseFrameSize(out_arg_size);

  // 6. Acquire lock for synchronized methods.
  if (is_synchronized) {
    // Compute arguments in registers to preserve
    mr_conv->ResetIterator(FrameOffset(frame_size + out_arg_size));
    std::vector<ManagedRegister> live_argument_regs;
    std::vector<size_t> live_argument_regs_size;
    while (mr_conv->HasNext()) {
      if (mr_conv->IsCurrentParamInRegister()) {
        live_argument_regs.push_back(mr_conv->CurrentParamRegister());
        live_argument_regs_size.push_back(mr_conv->CurrentParamSize());
      }
      mr_conv->Next();
    }

    // Copy arguments to preserve to callee save registers
    CHECK_LE(live_argument_regs.size(), callee_save_regs.size());
    for (size_t in = 0, out = 0; in < live_argument_regs.size(); ++in) {
      size_t size = live_argument_regs_size.at(in);
      if (IsRegisterPair(instruction_set, live_argument_regs.at(in))) {
        CHECK_EQ(instruction_set, kArm);
        arm::ArmManagedRegister pair(live_argument_regs.at(in).AsArm());
        arm::Register lo(pair.AsRegisterPairLow());
        arm::Register hi(pair.AsRegisterPairHigh());
        __ Move(callee_save_regs.at(out++), arm::ArmManagedRegister::FromCoreRegister(lo), size / 2);
        __ Move(callee_save_regs.at(out++), arm::ArmManagedRegister::FromCoreRegister(hi), size / 2);
      } else {
        __ Move(callee_save_regs.at(out++), live_argument_regs.at(in), size);
      }
    }

    // Get SIRT entry for 1st argument (jclass or this) to be 1st argument to
    // monitor enter
    mr_conv->ResetIterator(FrameOffset(frame_size + out_arg_size));
    jni_conv->ResetIterator(FrameOffset(out_arg_size));
    jni_conv->Next();  // Skip JNIEnv*
    if (is_static) {
      FrameOffset sirt_offset = jni_conv->CurrentParamSirtEntryOffset();
      if (jni_conv->IsCurrentParamOnStack()) {
        FrameOffset out_off = jni_conv->CurrentParamStackOffset();
        __ CreateSirtEntry(out_off, sirt_offset,
                           mr_conv->InterproceduralScratchRegister(),
                           false);
      } else {
        ManagedRegister out_reg = jni_conv->CurrentParamRegister();
        __ CreateSirtEntry(out_reg, sirt_offset,
                           ManagedRegister::NoRegister(), false);
      }
    } else {
      CopyParameter(jni_asm.get(), mr_conv.get(), jni_conv.get(), frame_size,
                    out_arg_size);
    }

    // Generate JNIEnv* in place and leave a copy in jni_fns_register
    jni_conv->ResetIterator(FrameOffset(out_arg_size));
    ManagedRegister jni_fns_register =
        jni_conv->InterproceduralScratchRegister();
    __ LoadRawPtrFromThread(jni_fns_register, Thread::JniEnvOffset());
    SetNativeParameter(jni_asm.get(), jni_conv.get(), jni_fns_register);

    // Call JNIEnv->MonitorEnter(object)
    __ LoadRawPtr(jni_fns_register, jni_fns_register, functions);
    __ Call(jni_fns_register, monitor_enter,
                  jni_conv->InterproceduralScratchRegister());

    // Check for exceptions
    __ ExceptionPoll(jni_conv->InterproceduralScratchRegister());

    // Restore live arguments
    for (size_t in = 0, out = 0; out < live_argument_regs.size(); ++out) {
      size_t size = live_argument_regs_size.at(out);
      if (IsRegisterPair(instruction_set, live_argument_regs.at(out))) {
        CHECK_EQ(instruction_set, kArm);
        arm::ArmManagedRegister pair(live_argument_regs.at(out).AsArm());
        arm::Register lo(pair.AsRegisterPairLow());
        arm::Register hi(pair.AsRegisterPairHigh());
        __ Move(arm::ArmManagedRegister::FromCoreRegister(lo), callee_save_regs.at(in++), size / 2);
        __ Move(arm::ArmManagedRegister::FromCoreRegister(hi), callee_save_regs.at(in++), size / 2);
      } else {
        __ Move(live_argument_regs.at(out), callee_save_regs.at(in++), size);
      }
    }
  }

  // 7. Iterate over arguments placing values from managed calling convention in
  //    to the convention required for a native call (shuffling). For references
  //    place an index/pointer to the reference after checking whether it is
  //    NULL (which must be encoded as NULL).
  //    Note: we do this prior to materializing the JNIEnv* and static's jclass to
  //    give as many free registers for the shuffle as possible
  mr_conv->ResetIterator(FrameOffset(frame_size+out_arg_size));
  uint32_t args_count = 0;
  while (mr_conv->HasNext()) {
    args_count++;
    mr_conv->Next();
  }

  // Do a backward pass over arguments, so that the generated code will be "mov
  // R2, R3; mov R1, R2" instead of "mov R1, R2; mov R2, R3."
  // TODO: A reverse iterator to improve readability.
  for (uint32_t i = 0; i < args_count; ++i) {
    mr_conv->ResetIterator(FrameOffset(frame_size + out_arg_size));
    jni_conv->ResetIterator(FrameOffset(out_arg_size));
    jni_conv->Next();  // Skip JNIEnv*
    if (is_static) {
      jni_conv->Next();  // Skip Class for now
    }
    for (uint32_t j = 0; j < args_count - i - 1; ++j) {
      mr_conv->Next();
      jni_conv->Next();
    }
    CopyParameter(jni_asm.get(), mr_conv.get(), jni_conv.get(), frame_size, out_arg_size);
  }

  if (is_static) {
    // Create argument for Class
    mr_conv->ResetIterator(FrameOffset(frame_size+out_arg_size));
    jni_conv->ResetIterator(FrameOffset(out_arg_size));
    jni_conv->Next();  // Skip JNIEnv*
    FrameOffset sirt_offset = jni_conv->CurrentParamSirtEntryOffset();
    if (jni_conv->IsCurrentParamOnStack()) {
      FrameOffset out_off = jni_conv->CurrentParamStackOffset();
      __ CreateSirtEntry(out_off, sirt_offset,
                         mr_conv->InterproceduralScratchRegister(),
                         false);
    } else {
      ManagedRegister out_reg = jni_conv->CurrentParamRegister();
      __ CreateSirtEntry(out_reg, sirt_offset,
                         ManagedRegister::NoRegister(), false);
    }
  }
  // 8. Create 1st argument, the JNI environment ptr and save the top of the local reference table
  jni_conv->ResetIterator(FrameOffset(out_arg_size));
  // Register that will hold local indirect reference table
  if (jni_conv->IsCurrentParamInRegister()) {
    ManagedRegister jni_env = jni_conv->CurrentParamRegister();
    DCHECK(!jni_env.Equals(jni_conv->InterproceduralScratchRegister()));
    __ LoadRawPtrFromThread(jni_env, Thread::JniEnvOffset());
    // Frame[saved_local_ref_cookie_offset] = env->local_ref_cookie
    __ Copy(jni_conv->SavedLocalReferenceCookieOffset(),
            jni_env, JNIEnvExt::LocalRefCookieOffset(),
            jni_conv->InterproceduralScratchRegister(), 4);
    // env->local_ref_cookie = env->locals.segment_state
    __ Copy(jni_env, JNIEnvExt::LocalRefCookieOffset(),
            jni_env, JNIEnvExt::SegmentStateOffset(),
            jni_conv->InterproceduralScratchRegister(), 4);
  } else {
    FrameOffset jni_env = jni_conv->CurrentParamStackOffset();
    __ CopyRawPtrFromThread(jni_env, Thread::JniEnvOffset(),
                            jni_conv->InterproceduralScratchRegister());
    // Frame[saved_local_ref_cookie_offset] = env->local_ref_cookie
    __ Copy(jni_conv->SavedLocalReferenceCookieOffset(),
            jni_env, JNIEnvExt::LocalRefCookieOffset(),
            jni_conv->InterproceduralScratchRegister(), 4);
    // env->local_ref_cookie = env->locals.segment_state
    __ Copy(jni_env, JNIEnvExt::LocalRefCookieOffset(),
            jni_env, JNIEnvExt::SegmentStateOffset(),
            jni_conv->InterproceduralScratchRegister(), 4);
  }

  // 9. Plant call to native code associated with method
  if (!jni_conv->IsMethodRegisterClobberedPreCall()) {
    // Method register shouldn't have been crushed by setting up outgoing
    // arguments
    __ Call(mr_conv->MethodRegister(), Method::NativeMethodOffset(),
            mr_conv->InterproceduralScratchRegister());
  } else {
    __ Call(jni_conv->MethodStackOffset(), Method::NativeMethodOffset(),
            mr_conv->InterproceduralScratchRegister());
  }

  // 10. Release lock for synchronized methods.
  if (is_synchronized) {
    mr_conv->ResetIterator(FrameOffset(frame_size+out_arg_size));
    jni_conv->ResetIterator(FrameOffset(out_arg_size));
    jni_conv->Next();  // Skip JNIEnv*
    // Save return value
    FrameOffset return_save_location = jni_conv->ReturnValueSaveLocation();
    if (jni_conv->SizeOfReturnValue() != 0) {
      FrameOffset return_save_location = jni_conv->ReturnValueSaveLocation();
      CHECK_LT(return_save_location.Uint32Value(), frame_size+out_arg_size);
      __ Store(return_save_location, jni_conv->ReturnRegister(),
               jni_conv->SizeOfReturnValue());
    }
    // Get SIRT entry for 1st argument
    if (is_static) {
      FrameOffset sirt_offset = jni_conv->CurrentParamSirtEntryOffset();
      if (jni_conv->IsCurrentParamOnStack()) {
        FrameOffset out_off = jni_conv->CurrentParamStackOffset();
        __ CreateSirtEntry(out_off, sirt_offset,
                           mr_conv->InterproceduralScratchRegister(),
                           false);
      } else {
        ManagedRegister out_reg = jni_conv->CurrentParamRegister();
        __ CreateSirtEntry(out_reg, sirt_offset,
                           ManagedRegister::NoRegister(), false);
      }
    } else {
      CopyParameter(jni_asm.get(), mr_conv.get(), jni_conv.get(), frame_size,
                    out_arg_size);
    }
    // Generate JNIEnv* in place and leave a copy in jni_env_register
    jni_conv->ResetIterator(FrameOffset(out_arg_size));
    ManagedRegister jni_env_register =
        jni_conv->InterproceduralScratchRegister();
    __ LoadRawPtrFromThread(jni_env_register, Thread::JniEnvOffset());
    SetNativeParameter(jni_asm.get(), jni_conv.get(), jni_env_register);
    // Call JNIEnv->MonitorExit(object)
    __ LoadRawPtr(jni_env_register, jni_env_register, functions);
    __ Call(jni_env_register, monitor_exit,
            jni_conv->InterproceduralScratchRegister());
    // Reload return value
    if (jni_conv->SizeOfReturnValue() != 0) {
      __ Load(jni_conv->ReturnRegister(), return_save_location,
              jni_conv->SizeOfReturnValue());
    }
  }

  // 11. Release outgoing argument area
  __ DecreaseFrameSize(out_arg_size);
  mr_conv->ResetIterator(FrameOffset(frame_size));
  jni_conv->ResetIterator(FrameOffset(0));

  // 12. Transition from being in native to managed code, possibly entering a
  //     safepoint
  // Don't clobber result
  CHECK(!jni_conv->InterproceduralScratchRegister().Equals(jni_conv->ReturnRegister()));
  // Location to preserve result on slow path, ensuring its within the frame
  FrameOffset return_save_location = jni_conv->ReturnValueSaveLocation();
  CHECK(return_save_location.Uint32Value() < frame_size ||
        jni_conv->SizeOfReturnValue() == 0);
  ChangeThreadState(jni_asm.get(), kRunnable,
                    jni_conv->InterproceduralScratchRegister(),
                    jni_conv->ReturnRegister(), return_save_location,
                    jni_conv->SizeOfReturnValue());

  // 13. Place result in correct register possibly loading from indirect
  //     reference table
  if (jni_conv->IsReturnAReference()) {
    __ IncreaseFrameSize(out_arg_size);
    jni_conv->ResetIterator(FrameOffset(out_arg_size));

    jni_conv->Next();  // Skip Thread* argument
    // Pass result as arg2
    SetNativeParameter(jni_asm.get(), jni_conv.get(),
                       jni_conv->ReturnRegister());

    // Pass Thread*
    jni_conv->ResetIterator(FrameOffset(out_arg_size));
    if (jni_conv->IsCurrentParamInRegister()) {
      __ GetCurrentThread(jni_conv->CurrentParamRegister());
      __ Call(jni_conv->CurrentParamRegister(),
              Offset(ENTRYPOINT_OFFSET(pDecodeJObjectInThread)),
              jni_conv->InterproceduralScratchRegister());
    } else {
      __ GetCurrentThread(jni_conv->CurrentParamStackOffset(),
                          jni_conv->InterproceduralScratchRegister());
      __ Call(ThreadOffset(ENTRYPOINT_OFFSET(pDecodeJObjectInThread)),
              jni_conv->InterproceduralScratchRegister());
    }

    __ DecreaseFrameSize(out_arg_size);
    jni_conv->ResetIterator(FrameOffset(0));
  }
  DCHECK_EQ(mr_conv->SizeOfReturnValue(), jni_conv->SizeOfReturnValue());
  __ Move(mr_conv->ReturnRegister(), jni_conv->ReturnRegister(), mr_conv->SizeOfReturnValue());

  // 14. Restore segment state and remove SIRT from thread
  {
    ManagedRegister jni_env = jni_conv->InterproceduralScratchRegister();
    __ LoadRawPtrFromThread(jni_env, Thread::JniEnvOffset());
    // env->locals.segment_state = env->local_ref_cookie
    __ Copy(jni_env, JNIEnvExt::SegmentStateOffset(),
            jni_env, JNIEnvExt::LocalRefCookieOffset(),
            jni_conv->ReturnScratchRegister(), 4);
    // env->local_ref_cookie = Frame[saved_local_ref_cookie_offset]
    __ Copy(jni_env, JNIEnvExt::LocalRefCookieOffset(),
            jni_conv->SavedLocalReferenceCookieOffset(),
            jni_conv->ReturnScratchRegister(), 4);
  }
  __ CopyRawPtrToThread(Thread::TopSirtOffset(), jni_conv->SirtLinkOffset(),
                        jni_conv->InterproceduralScratchRegister());

  // 15. Check for pending exception and forward if there
  __ ExceptionPoll(jni_conv->InterproceduralScratchRegister());

  // 16. Remove activation
  if (is_synchronized) {
    __ RemoveFrame(frame_size, callee_save_regs);
  } else {
    // no need to restore callee save registers because we didn't
    // clobber them while locking the monitor.
    __ RemoveFrame(frame_size, std::vector<ManagedRegister>());
  }

  // 17. Finalize code generation
  __ EmitSlowPaths();
  size_t cs = __ CodeSize();
  std::vector<uint8_t> managed_code(cs);
  MemoryRegion code(&managed_code[0], managed_code.size());
  __ FinalizeInstructions(code);
  if (should_disassemble) {
    UniquePtr<Disassembler> disassembler(Disassembler::Create(instruction_set));
    disassembler->Dump(LOG(INFO), &managed_code[0], &managed_code[managed_code.size()]);
  }
  return new CompiledMethod(instruction_set,
                            managed_code,
                            frame_size,
                            jni_conv->CoreSpillMask(),
                            jni_conv->FpSpillMask());
}

}  // namespace art

extern "C" art::CompiledMethod* ArtJniCompileMethod(art::Compiler& compiler,
                                                    uint32_t access_flags, uint32_t method_idx,
                                                    const art::DexFile& dex_file) {
  return ArtJniCompileMethodInternal(compiler, access_flags, method_idx, dex_file);
}