Implement Reference.getReferent() intrinsic.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing --jit
Test: aosp_blueline-userdebug boots.
Test: run-gtests.sh
Test: testrunner.py --target --optimizing --jit
Bug: 170286013
Change-Id: I4762f7c1cf3d61de2215ec8f1d14be80289c2372

9 files changed, 308 insertions, 29 deletions

diff --git a/compiler/optimizing/code_generator_arm_vixl.cc b/compiler/optimizing/code_generator_arm_vixl.cc
index 00b258685c..1dedfc580c 100644
--- a/compiler/optimizing/code_generator_arm_vixl.cc
+++ b/compiler/optimizing/code_generator_arm_vixl.cc
@@ -8893,12 +8893,12 @@ void CodeGeneratorARMVIXL::GenerateFieldLoadWithBakerReadBarrier(HInstruction* i
                                                                  Location ref,
                                                                  vixl32::Register obj,
                                                                  uint32_t offset,
-                                                                 Location temp,
+                                                                 Location maybe_temp,
                                                                  bool needs_null_check) {
   DCHECK_ALIGNED(offset, sizeof(mirror::HeapReference<mirror::Object>));
   vixl32::Register base = obj;
   if (offset >= kReferenceLoadMinFarOffset) {
-    base = RegisterFrom(temp);
+    base = RegisterFrom(maybe_temp);
     static_assert(IsPowerOfTwo(kReferenceLoadMinFarOffset), "Expecting a power of 2.");
     __ Add(base, obj, Operand(offset & ~(kReferenceLoadMinFarOffset - 1u)));
     offset &= (kReferenceLoadMinFarOffset - 1u);
diff --git a/compiler/optimizing/code_generator_arm_vixl.h b/compiler/optimizing/code_generator_arm_vixl.h
index 8f3d41cbf2..23d05ae7df 100644
--- a/compiler/optimizing/code_generator_arm_vixl.h
+++ b/compiler/optimizing/code_generator_arm_vixl.h
@@ -677,7 +677,7 @@ class CodeGeneratorARMVIXL : public CodeGenerator {
                                              Location ref,
                                              vixl::aarch32::Register obj,
                                              uint32_t offset,
-                                             Location temp,
+                                             Location maybe_temp,
                                              bool needs_null_check);
   // Fast path implementation of ReadBarrier::Barrier for a heap
   // reference array load when Baker's read barriers are used.
diff --git a/compiler/optimizing/intrinsics.cc b/compiler/optimizing/intrinsics.cc
index 1663ee91b4..10d0b8992c 100644
--- a/compiler/optimizing/intrinsics.cc
+++ b/compiler/optimizing/intrinsics.cc
@@ -146,6 +146,22 @@ static bool CheckIntegerCache(Thread* self,
   return true;
 }
 
+static bool CanReferenceBootImageObjects(HInvoke* invoke, const CompilerOptions& compiler_options) {
+  // Piggyback on the method load kind to determine whether we can use PC-relative addressing
+  // for AOT. This should cover both the testing config (non-PIC boot image) and codegens that
+  // reject PC-relative load kinds and fall back to the runtime call.
+  if (compiler_options.IsAotCompiler() &&
+      !invoke->AsInvokeStaticOrDirect()->HasPcRelativeMethodLoadKind()) {
+    return false;
+  }
+  if (!compiler_options.IsBootImage() &&
+      Runtime::Current()->GetHeap()->GetBootImageSpaces().empty()) {
+    DCHECK(compiler_options.IsJitCompiler());
+    return false;  // Running without boot image, cannot use required boot image objects.
+  }
+  return true;
+}
+
 void IntrinsicVisitor::ComputeIntegerValueOfLocations(HInvoke* invoke,
                                                       CodeGenerator* codegen,
                                                       Location return_location,
@@ -153,11 +169,7 @@ void IntrinsicVisitor::ComputeIntegerValueOfLocations(HInvoke* invoke,
   // The intrinsic will call if it needs to allocate a j.l.Integer.
   LocationSummary::CallKind call_kind = LocationSummary::kCallOnMainOnly;
   const CompilerOptions& compiler_options = codegen->GetCompilerOptions();
-  // Piggyback on the method load kind to determine whether we can use PC-relative addressing
-  // for AOT. This should cover both the testing config (non-PIC boot image) and codegens that
-  // reject PC-relative load kinds and fall back to the runtime call.
-  if (compiler_options.IsAotCompiler() &&
-      !invoke->AsInvokeStaticOrDirect()->HasPcRelativeMethodLoadKind()) {
+  if (!CanReferenceBootImageObjects(invoke, compiler_options)) {
     return;
   }
   if (compiler_options.IsBootImage()) {
@@ -206,9 +218,6 @@ void IntrinsicVisitor::ComputeIntegerValueOfLocations(HInvoke* invoke,
     }
   } else {
     Runtime* runtime = Runtime::Current();
-    if (runtime->GetHeap()->GetBootImageSpaces().empty()) {
-      return;  // Running without boot image, cannot use required boot image objects.
-    }
     Thread* self = Thread::Current();
     ScopedObjectAccess soa(self);
     ObjPtr<mirror::ObjectArray<mirror::Object>> boot_image_live_objects = GetBootImageLiveObjects();
@@ -244,7 +253,7 @@ void IntrinsicVisitor::ComputeIntegerValueOfLocations(HInvoke* invoke,
     }
   }
 
-  ArenaAllocator* allocator = invoke->GetBlock()->GetGraph()->GetAllocator();
+  ArenaAllocator* allocator = codegen->GetGraph()->GetAllocator();
   LocationSummary* locations = new (allocator) LocationSummary(invoke, call_kind, kIntrinsified);
   if (call_kind == LocationSummary::kCallOnMainOnly) {
     locations->SetInAt(0, Location::RegisterOrConstant(invoke->InputAt(0)));
@@ -354,10 +363,39 @@ IntrinsicVisitor::IntegerValueOfInfo IntrinsicVisitor::ComputeIntegerValueOfInfo
   return info;
 }
 
+MemberOffset IntrinsicVisitor::GetReferenceDisableIntrinsicOffset() {
+  ScopedObjectAccess soa(Thread::Current());
+  // The "disableIntrinsic" is the first static field.
+  ArtField* field = GetClassRoot<mirror::Reference>()->GetStaticField(0);
+  DCHECK_STREQ(field->GetName(), "disableIntrinsic");
+  return field->GetOffset();
+}
+
+MemberOffset IntrinsicVisitor::GetReferenceSlowPathEnabledOffset() {
+  ScopedObjectAccess soa(Thread::Current());
+  // The "slowPathEnabled" is the second static field.
+  ArtField* field = GetClassRoot<mirror::Reference>()->GetStaticField(1);
+  DCHECK_STREQ(field->GetName(), "slowPathEnabled");
+  return field->GetOffset();
+}
+
+void IntrinsicVisitor::CreateReferenceGetReferentLocations(HInvoke* invoke,
+                                                           CodeGenerator* codegen) {
+  if (!CanReferenceBootImageObjects(invoke, codegen->GetCompilerOptions())) {
+    return;
+  }
+
+  ArenaAllocator* allocator = codegen->GetGraph()->GetAllocator();
+  LocationSummary* locations =
+      new (allocator) LocationSummary(invoke, LocationSummary::kCallOnSlowPath, kIntrinsified);
+  locations->SetInAt(0, Location::RequiresRegister());
+  locations->SetOut(Location::RequiresRegister());
+}
+
 void IntrinsicVisitor::AssertNonMovableStringClass() {
   if (kIsDebugBuild) {
     ScopedObjectAccess soa(Thread::Current());
-    ObjPtr<mirror::Class> string_class = GetClassRoot<art::mirror::String>();
+    ObjPtr<mirror::Class> string_class = GetClassRoot<mirror::String>();
     CHECK(!art::Runtime::Current()->GetHeap()->IsMovableObject(string_class));
   }
 }
diff --git a/compiler/optimizing/intrinsics.h b/compiler/optimizing/intrinsics.h
index cc26e41067..a0f9420d95 100644
--- a/compiler/optimizing/intrinsics.h
+++ b/compiler/optimizing/intrinsics.h
@@ -136,6 +136,10 @@ class IntrinsicVisitor : public ValueObject {
   static IntegerValueOfInfo ComputeIntegerValueOfInfo(
       HInvoke* invoke, const CompilerOptions& compiler_options);
 
+  static MemberOffset GetReferenceDisableIntrinsicOffset();
+  static MemberOffset GetReferenceSlowPathEnabledOffset();
+  static void CreateReferenceGetReferentLocations(HInvoke* invoke, CodeGenerator* codegen);
+
  protected:
   IntrinsicVisitor() {}
 
diff --git a/compiler/optimizing/intrinsics_arm64.cc b/compiler/optimizing/intrinsics_arm64.cc
index a7d5b31820..1c8c5e11e4 100644
--- a/compiler/optimizing/intrinsics_arm64.cc
+++ b/compiler/optimizing/intrinsics_arm64.cc
@@ -2873,6 +2873,66 @@ void IntrinsicCodeGeneratorARM64::VisitIntegerValueOf(HInvoke* invoke) {
   }
 }
 
+void IntrinsicLocationsBuilderARM64::VisitReferenceGetReferent(HInvoke* invoke) {
+  IntrinsicVisitor::CreateReferenceGetReferentLocations(invoke, codegen_);
+
+  if (kEmitCompilerReadBarrier && kUseBakerReadBarrier && invoke->GetLocations() != nullptr) {
+    invoke->GetLocations()->AddTemp(Location::RequiresRegister());
+  }
+}
+
+void IntrinsicCodeGeneratorARM64::VisitReferenceGetReferent(HInvoke* invoke) {
+  MacroAssembler* masm = GetVIXLAssembler();
+  LocationSummary* locations = invoke->GetLocations();
+
+  Location obj = locations->InAt(0);
+  Location out = locations->Out();
+
+  SlowPathCodeARM64* slow_path = new (GetAllocator()) IntrinsicSlowPathARM64(invoke);
+  codegen_->AddSlowPath(slow_path);
+
+  if (kEmitCompilerReadBarrier) {
+    // Check self->GetWeakRefAccessEnabled().
+    UseScratchRegisterScope temps(masm);
+    Register temp = temps.AcquireW();
+    __ Ldr(temp,
+           MemOperand(tr, Thread::WeakRefAccessEnabledOffset<kArm64PointerSize>().Uint32Value()));
+    __ Cbz(temp, slow_path->GetEntryLabel());
+  }
+
+  {
+    // Load the java.lang.ref.Reference class.
+    UseScratchRegisterScope temps(masm);
+    Register temp = temps.AcquireW();
+    codegen_->LoadIntrinsicDeclaringClass(temp, invoke);
+
+    // Check static fields java.lang.ref.Reference.{disableIntrinsic,slowPathEnabled} together.
+    MemberOffset disable_intrinsic_offset = IntrinsicVisitor::GetReferenceDisableIntrinsicOffset();
+    DCHECK_ALIGNED(disable_intrinsic_offset.Uint32Value(), 2u);
+    DCHECK_EQ(disable_intrinsic_offset.Uint32Value() + 1u,
+              IntrinsicVisitor::GetReferenceSlowPathEnabledOffset().Uint32Value());
+    __ Ldrh(temp, HeapOperand(temp, disable_intrinsic_offset.Uint32Value()));
+    __ Cbnz(temp, slow_path->GetEntryLabel());
+  }
+
+  // Load the value from the field.
+  uint32_t referent_offset = mirror::Reference::ReferentOffset().Uint32Value();
+  if (kEmitCompilerReadBarrier && kUseBakerReadBarrier) {
+    codegen_->GenerateFieldLoadWithBakerReadBarrier(invoke,
+                                                    out,
+                                                    WRegisterFrom(obj),
+                                                    referent_offset,
+                                                    /*maybe_temp=*/ locations->GetTemp(0),
+                                                    /*needs_null_check=*/ true,
+                                                    /*use_load_acquire=*/ true);
+  } else {
+    MemOperand field = HeapOperand(WRegisterFrom(obj), referent_offset);
+    codegen_->LoadAcquire(invoke, WRegisterFrom(out), field, /*needs_null_check=*/ true);
+    codegen_->MaybeGenerateReadBarrierSlow(invoke, out, out, obj, referent_offset);
+  }
+  __ Bind(slow_path->GetExitLabel());
+}
+
 void IntrinsicLocationsBuilderARM64::VisitThreadInterrupted(HInvoke* invoke) {
   LocationSummary* locations =
       new (allocator_) LocationSummary(invoke, LocationSummary::kNoCall, kIntrinsified);
@@ -3828,8 +3888,6 @@ void IntrinsicCodeGeneratorARM64::VisitVarHandleSetVolatile(HInvoke* invoke) {
   GenerateVarHandleSet(invoke, codegen_, /*use_store_release=*/ true);
 }
 
-UNIMPLEMENTED_INTRINSIC(ARM64, ReferenceGetReferent)
-
 UNIMPLEMENTED_INTRINSIC(ARM64, StringStringIndexOf);
 UNIMPLEMENTED_INTRINSIC(ARM64, StringStringIndexOfAfter);
 UNIMPLEMENTED_INTRINSIC(ARM64, StringBufferAppend);
diff --git a/compiler/optimizing/intrinsics_arm_vixl.cc b/compiler/optimizing/intrinsics_arm_vixl.cc
index 2901c472bc..f629ad3c51 100644
--- a/compiler/optimizing/intrinsics_arm_vixl.cc
+++ b/compiler/optimizing/intrinsics_arm_vixl.cc
@@ -2991,6 +2991,68 @@ void IntrinsicCodeGeneratorARMVIXL::VisitIntegerValueOf(HInvoke* invoke) {
   }
 }
 
+void IntrinsicLocationsBuilderARMVIXL::VisitReferenceGetReferent(HInvoke* invoke) {
+  IntrinsicVisitor::CreateReferenceGetReferentLocations(invoke, codegen_);
+}
+
+void IntrinsicCodeGeneratorARMVIXL::VisitReferenceGetReferent(HInvoke* invoke) {
+  ArmVIXLAssembler* assembler = GetAssembler();
+  LocationSummary* locations = invoke->GetLocations();
+
+  Location obj = locations->InAt(0);
+  Location out = locations->Out();
+
+  SlowPathCodeARMVIXL* slow_path = new (GetAllocator()) IntrinsicSlowPathARMVIXL(invoke);
+  codegen_->AddSlowPath(slow_path);
+
+  if (kEmitCompilerReadBarrier) {
+    // Check self->GetWeakRefAccessEnabled().
+    UseScratchRegisterScope temps(assembler->GetVIXLAssembler());
+    vixl32::Register temp = temps.Acquire();
+    __ Ldr(temp,
+           MemOperand(tr, Thread::WeakRefAccessEnabledOffset<kArmPointerSize>().Uint32Value()));
+    __ Cmp(temp, 0);
+    __ B(eq, slow_path->GetEntryLabel());
+  }
+
+  {
+    // Load the java.lang.ref.Reference class.
+    UseScratchRegisterScope temps(assembler->GetVIXLAssembler());
+    vixl32::Register temp = temps.Acquire();
+    codegen_->LoadIntrinsicDeclaringClass(temp, invoke);
+
+    // Check static fields java.lang.ref.Reference.{disableIntrinsic,slowPathEnabled} together.
+    MemberOffset disable_intrinsic_offset = IntrinsicVisitor::GetReferenceDisableIntrinsicOffset();
+    DCHECK_ALIGNED(disable_intrinsic_offset.Uint32Value(), 2u);
+    DCHECK_EQ(disable_intrinsic_offset.Uint32Value() + 1u,
+              IntrinsicVisitor::GetReferenceSlowPathEnabledOffset().Uint32Value());
+    __ Ldrh(temp, MemOperand(temp, disable_intrinsic_offset.Uint32Value()));
+    __ Cmp(temp, 0);
+    __ B(ne, slow_path->GetEntryLabel());
+  }
+
+  // Load the value from the field.
+  uint32_t referent_offset = mirror::Reference::ReferentOffset().Uint32Value();
+  if (kEmitCompilerReadBarrier && kUseBakerReadBarrier) {
+    codegen_->GenerateFieldLoadWithBakerReadBarrier(invoke,
+                                                    out,
+                                                    RegisterFrom(obj),
+                                                    referent_offset,
+                                                    /*maybe_temp=*/ Location::NoLocation(),
+                                                    /*needs_null_check=*/ true);
+    codegen_->GenerateMemoryBarrier(MemBarrierKind::kLoadAny);  // `referent` is volatile.
+  } else {
+    {
+      vixl::EmissionCheckScope guard(codegen_->GetVIXLAssembler(), kMaxMacroInstructionSizeInBytes);
+      __ Ldr(RegisterFrom(out), MemOperand(RegisterFrom(obj), referent_offset));
+      codegen_->MaybeRecordImplicitNullCheck(invoke);
+    }
+    codegen_->GenerateMemoryBarrier(MemBarrierKind::kLoadAny);  // `referent` is volatile.
+    codegen_->MaybeGenerateReadBarrierSlow(invoke, out, out, obj, referent_offset);
+  }
+  __ Bind(slow_path->GetExitLabel());
+}
+
 void IntrinsicLocationsBuilderARMVIXL::VisitThreadInterrupted(HInvoke* invoke) {
   LocationSummary* locations =
       new (allocator_) LocationSummary(invoke, LocationSummary::kNoCall, kIntrinsified);
@@ -3049,7 +3111,6 @@ void IntrinsicCodeGeneratorARMVIXL::VisitIntegerDivideUnsigned(HInvoke* invoke)
 UNIMPLEMENTED_INTRINSIC(ARMVIXL, MathRoundDouble)   // Could be done by changing rounding mode, maybe?
 UNIMPLEMENTED_INTRINSIC(ARMVIXL, UnsafeCASLong)     // High register pressure.
 UNIMPLEMENTED_INTRINSIC(ARMVIXL, SystemArrayCopyChar)
-UNIMPLEMENTED_INTRINSIC(ARMVIXL, ReferenceGetReferent)
 UNIMPLEMENTED_INTRINSIC(ARMVIXL, LongDivideUnsigned)
 UNIMPLEMENTED_INTRINSIC(ARMVIXL, CRC32Update)
 UNIMPLEMENTED_INTRINSIC(ARMVIXL, CRC32UpdateBytes)
diff --git a/compiler/optimizing/intrinsics_x86.cc b/compiler/optimizing/intrinsics_x86.cc
index 4095259f38..cd41e1a13b 100644
--- a/compiler/optimizing/intrinsics_x86.cc
+++ b/compiler/optimizing/intrinsics_x86.cc
@@ -3014,6 +3014,21 @@ void IntrinsicCodeGeneratorX86::VisitSystemArrayCopy(HInvoke* invoke) {
   __ Bind(intrinsic_slow_path->GetExitLabel());
 }
 
+static void RequestBaseMethodAddressInRegister(HInvoke* invoke) {
+  LocationSummary* locations = invoke->GetLocations();
+  if (locations != nullptr) {
+    HInvokeStaticOrDirect* invoke_static_or_direct = invoke->AsInvokeStaticOrDirect();
+    // Note: The base method address is not present yet when this is called from the
+    // PCRelativeHandlerVisitor via IsCallFreeIntrinsic() to determine whether to insert it.
+    if (invoke_static_or_direct->HasSpecialInput()) {
+      DCHECK(invoke_static_or_direct->InputAt(invoke_static_or_direct->GetSpecialInputIndex())
+                 ->IsX86ComputeBaseMethodAddress());
+      locations->SetInAt(invoke_static_or_direct->GetSpecialInputIndex(),
+                         Location::RequiresRegister());
+    }
+  }
+}
+
 void IntrinsicLocationsBuilderX86::VisitIntegerValueOf(HInvoke* invoke) {
   DCHECK(invoke->IsInvokeStaticOrDirect());
   InvokeRuntimeCallingConvention calling_convention;
@@ -3022,17 +3037,7 @@ void IntrinsicLocationsBuilderX86::VisitIntegerValueOf(HInvoke* invoke) {
       codegen_,
       Location::RegisterLocation(EAX),
       Location::RegisterLocation(calling_convention.GetRegisterAt(0)));
-
-  LocationSummary* locations = invoke->GetLocations();
-  if (locations != nullptr) {
-    HInvokeStaticOrDirect* invoke_static_or_direct = invoke->AsInvokeStaticOrDirect();
-    if (invoke_static_or_direct->HasSpecialInput() &&
-        invoke->InputAt(invoke_static_or_direct->GetSpecialInputIndex())
-            ->IsX86ComputeBaseMethodAddress()) {
-      locations->SetInAt(invoke_static_or_direct->GetSpecialInputIndex(),
-                         Location::RequiresRegister());
-    }
-  }
+  RequestBaseMethodAddressInRegister(invoke);
 }
 
 void IntrinsicCodeGeneratorX86::VisitIntegerValueOf(HInvoke* invoke) {
@@ -3107,6 +3112,61 @@ void IntrinsicCodeGeneratorX86::VisitIntegerValueOf(HInvoke* invoke) {
   }
 }
 
+void IntrinsicLocationsBuilderX86::VisitReferenceGetReferent(HInvoke* invoke) {
+  IntrinsicVisitor::CreateReferenceGetReferentLocations(invoke, codegen_);
+  RequestBaseMethodAddressInRegister(invoke);
+}
+
+void IntrinsicCodeGeneratorX86::VisitReferenceGetReferent(HInvoke* invoke) {
+  X86Assembler* assembler = GetAssembler();
+  LocationSummary* locations = invoke->GetLocations();
+
+  Location obj = locations->InAt(0);
+  Location out = locations->Out();
+
+  SlowPathCode* slow_path = new (GetAllocator()) IntrinsicSlowPathX86(invoke);
+  codegen_->AddSlowPath(slow_path);
+
+  if (kEmitCompilerReadBarrier) {
+    // Check self->GetWeakRefAccessEnabled().
+    ThreadOffset32 offset = Thread::WeakRefAccessEnabledOffset<kX86PointerSize>();
+    __ fs()->cmpl(Address::Absolute(offset), Immediate(0));
+    __ j(kEqual, slow_path->GetEntryLabel());
+  }
+
+  // Load the java.lang.ref.Reference class, use the output register as a temporary.
+  codegen_->LoadIntrinsicDeclaringClass(out.AsRegister<Register>(),
+                                        invoke->AsInvokeStaticOrDirect());
+
+  // Check static fields java.lang.ref.Reference.{disableIntrinsic,slowPathEnabled} together.
+  MemberOffset disable_intrinsic_offset = IntrinsicVisitor::GetReferenceDisableIntrinsicOffset();
+  DCHECK_ALIGNED(disable_intrinsic_offset.Uint32Value(), 2u);
+  DCHECK_EQ(disable_intrinsic_offset.Uint32Value() + 1u,
+            IntrinsicVisitor::GetReferenceSlowPathEnabledOffset().Uint32Value());
+  __ cmpw(Address(out.AsRegister<Register>(), disable_intrinsic_offset.Uint32Value()),
+          Immediate(0));
+  __ j(kNotEqual, slow_path->GetEntryLabel());
+
+  // Load the value from the field.
+  uint32_t referent_offset = mirror::Reference::ReferentOffset().Uint32Value();
+  if (kEmitCompilerReadBarrier && kUseBakerReadBarrier) {
+    codegen_->GenerateFieldLoadWithBakerReadBarrier(invoke,
+                                                    out,
+                                                    obj.AsRegister<Register>(),
+                                                    referent_offset,
+                                                    /*needs_null_check=*/ true);
+    // Note that the fence is a no-op, thanks to the x86 memory model.
+    codegen_->GenerateMemoryBarrier(MemBarrierKind::kLoadAny);  // `referent` is volatile.
+  } else {
+    __ movl(out.AsRegister<Register>(), Address(obj.AsRegister<Register>(), referent_offset));
+    codegen_->MaybeRecordImplicitNullCheck(invoke);
+    // Note that the fence is a no-op, thanks to the x86 memory model.
+    codegen_->GenerateMemoryBarrier(MemBarrierKind::kLoadAny);  // `referent` is volatile.
+    codegen_->MaybeGenerateReadBarrierSlow(invoke, out, out, obj, referent_offset);
+  }
+  __ Bind(slow_path->GetExitLabel());
+}
+
 void IntrinsicLocationsBuilderX86::VisitThreadInterrupted(HInvoke* invoke) {
   LocationSummary* locations =
       new (allocator_) LocationSummary(invoke, LocationSummary::kNoCall, kIntrinsified);
@@ -4499,7 +4559,6 @@ void IntrinsicCodeGeneratorX86::VisitVarHandleGetAndBitwiseAndRelease(HInvoke* i
 }
 
 UNIMPLEMENTED_INTRINSIC(X86, MathRoundDouble)
-UNIMPLEMENTED_INTRINSIC(X86, ReferenceGetReferent)
 UNIMPLEMENTED_INTRINSIC(X86, FloatIsInfinite)
 UNIMPLEMENTED_INTRINSIC(X86, DoubleIsInfinite)
 UNIMPLEMENTED_INTRINSIC(X86, IntegerHighestOneBit)
diff --git a/compiler/optimizing/intrinsics_x86_64.cc b/compiler/optimizing/intrinsics_x86_64.cc
index 985f09590c..c22fdd9092 100644
--- a/compiler/optimizing/intrinsics_x86_64.cc
+++ b/compiler/optimizing/intrinsics_x86_64.cc
@@ -2659,6 +2659,59 @@ void IntrinsicCodeGeneratorX86_64::VisitIntegerValueOf(HInvoke* invoke) {
   }
 }
 
+void IntrinsicLocationsBuilderX86_64::VisitReferenceGetReferent(HInvoke* invoke) {
+  IntrinsicVisitor::CreateReferenceGetReferentLocations(invoke, codegen_);
+}
+
+void IntrinsicCodeGeneratorX86_64::VisitReferenceGetReferent(HInvoke* invoke) {
+  X86_64Assembler* assembler = GetAssembler();
+  LocationSummary* locations = invoke->GetLocations();
+
+  Location obj = locations->InAt(0);
+  Location out = locations->Out();
+
+  SlowPathCode* slow_path = new (GetAllocator()) IntrinsicSlowPathX86_64(invoke);
+  codegen_->AddSlowPath(slow_path);
+
+  if (kEmitCompilerReadBarrier) {
+    // Check self->GetWeakRefAccessEnabled().
+    ThreadOffset64 offset = Thread::WeakRefAccessEnabledOffset<kX86_64PointerSize>();
+    __ gs()->cmpl(Address::Absolute(offset, /* no_rip= */ true), Immediate(0));
+    __ j(kEqual, slow_path->GetEntryLabel());
+  }
+
+  // Load the java.lang.ref.Reference class, use the output register as a temporary.
+  codegen_->LoadIntrinsicDeclaringClass(out.AsRegister<CpuRegister>(), invoke);
+
+  // Check static fields java.lang.ref.Reference.{disableIntrinsic,slowPathEnabled} together.
+  MemberOffset disable_intrinsic_offset = IntrinsicVisitor::GetReferenceDisableIntrinsicOffset();
+  DCHECK_ALIGNED(disable_intrinsic_offset.Uint32Value(), 2u);
+  DCHECK_EQ(disable_intrinsic_offset.Uint32Value() + 1u,
+            IntrinsicVisitor::GetReferenceSlowPathEnabledOffset().Uint32Value());
+  __ cmpw(Address(out.AsRegister<CpuRegister>(), disable_intrinsic_offset.Uint32Value()),
+          Immediate(0));
+  __ j(kNotEqual, slow_path->GetEntryLabel());
+
+  // Load the value from the field.
+  uint32_t referent_offset = mirror::Reference::ReferentOffset().Uint32Value();
+  if (kEmitCompilerReadBarrier && kUseBakerReadBarrier) {
+    codegen_->GenerateFieldLoadWithBakerReadBarrier(invoke,
+                                                    out,
+                                                    obj.AsRegister<CpuRegister>(),
+                                                    referent_offset,
+                                                    /*needs_null_check=*/ true);
+    // Note that the fence is a no-op, thanks to the x86-64 memory model.
+    codegen_->GenerateMemoryBarrier(MemBarrierKind::kLoadAny);  // `referent` is volatile.
+  } else {
+    __ movl(out.AsRegister<CpuRegister>(), Address(obj.AsRegister<CpuRegister>(), referent_offset));
+    codegen_->MaybeRecordImplicitNullCheck(invoke);
+    // Note that the fence is a no-op, thanks to the x86-64 memory model.
+    codegen_->GenerateMemoryBarrier(MemBarrierKind::kLoadAny);  // `referent` is volatile.
+    codegen_->MaybeGenerateReadBarrierSlow(invoke, out, out, obj, referent_offset);
+  }
+  __ Bind(slow_path->GetExitLabel());
+}
+
 void IntrinsicLocationsBuilderX86_64::VisitThreadInterrupted(HInvoke* invoke) {
   LocationSummary* locations =
       new (allocator_) LocationSummary(invoke, LocationSummary::kNoCall, kIntrinsified);
@@ -2723,7 +2776,6 @@ void IntrinsicCodeGeneratorX86_64::VisitIntegerDivideUnsigned(HInvoke* invoke) {
 }
 
 
-UNIMPLEMENTED_INTRINSIC(X86_64, ReferenceGetReferent)
 UNIMPLEMENTED_INTRINSIC(X86_64, FloatIsInfinite)
 UNIMPLEMENTED_INTRINSIC(X86_64, DoubleIsInfinite)
 UNIMPLEMENTED_INTRINSIC(X86_64, CRC32Update)
diff --git a/runtime/thread.h b/runtime/thread.h
index 8cd16c3be7..b23f6470eb 100644
--- a/runtime/thread.h
+++ b/runtime/thread.h
@@ -689,6 +689,13 @@ class Thread {
   }
 
   template<PointerSize pointer_size>
+  static constexpr ThreadOffset<pointer_size> WeakRefAccessEnabledOffset() {
+    return ThreadOffset<pointer_size>(
+        OFFSETOF_MEMBER(Thread, tls32_) +
+        OFFSETOF_MEMBER(tls_32bit_sized_values, weak_ref_access_enabled));
+  }
+
+  template<PointerSize pointer_size>
   static constexpr ThreadOffset<pointer_size> ThreadFlagsOffset() {
     return ThreadOffset<pointer_size>(
         OFFSETOF_MEMBER(Thread, tls32_) +