diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 2b63f3d..7fe3960 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -427,7 +427,9 @@
            instruction_->IsLoadClass() ||
            instruction_->IsLoadString() ||
            instruction_->IsInstanceOf() ||
-           instruction_->IsCheckCast())
+           instruction_->IsCheckCast() ||
+           ((instruction_->IsInvokeStaticOrDirect() || instruction_->IsInvokeVirtual()) &&
+            instruction_->GetLocations()->Intrinsified()))
         << "Unexpected instruction in read barrier marking slow path: "
         << instruction_->DebugName();
 
@@ -490,8 +492,12 @@
     Register reg_out = out_.AsRegister<Register>();
     DCHECK(locations->CanCall());
     DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(reg_out));
-    DCHECK(!instruction_->IsInvoke() ||
-           (instruction_->IsInvokeStaticOrDirect() &&
+    DCHECK(instruction_->IsInstanceFieldGet() ||
+           instruction_->IsStaticFieldGet() ||
+           instruction_->IsArrayGet() ||
+           instruction_->IsInstanceOf() ||
+           instruction_->IsCheckCast() ||
+           ((instruction_->IsInvokeStaticOrDirect() || instruction_->IsInvokeVirtual()) &&
             instruction_->GetLocations()->Intrinsified()))
         << "Unexpected instruction in read barrier for heap reference slow path: "
         << instruction_->DebugName();
@@ -504,7 +510,7 @@
     // introduce a copy of it, `index`.
     Location index = index_;
     if (index_.IsValid()) {
-      // Handle `index_` for HArrayGet and intrinsic UnsafeGetObject.
+      // Handle `index_` for HArrayGet and UnsafeGetObject/UnsafeGetObjectVolatile intrinsics.
       if (instruction_->IsArrayGet()) {
         // Compute the actual memory offset and store it in `index`.
         Register index_reg = index_.AsRegister<Register>();
@@ -552,7 +558,11 @@
             "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
         __ AddConstant(index_reg, index_reg, offset_);
       } else {
-        DCHECK(instruction_->IsInvoke());
+        // In the case of the UnsafeGetObject/UnsafeGetObjectVolatile
+        // intrinsics, `index_` is not shifted by a scale factor of 2
+        // (as in the case of ArrayGet), as it is actually an offset
+        // to an object field within an object.
+        DCHECK(instruction_->IsInvoke()) << instruction_->DebugName();
         DCHECK(instruction_->GetLocations()->Intrinsified());
         DCHECK((instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObject) ||
                (instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObjectVolatile))
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index dc5802a..c5d09c8 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -595,7 +595,9 @@
            instruction_->IsLoadClass() ||
            instruction_->IsLoadString() ||
            instruction_->IsInstanceOf() ||
-           instruction_->IsCheckCast())
+           instruction_->IsCheckCast() ||
+           ((instruction_->IsInvokeStaticOrDirect() || instruction_->IsInvokeVirtual()) &&
+            instruction_->GetLocations()->Intrinsified()))
         << "Unexpected instruction in read barrier marking slow path: "
         << instruction_->DebugName();
 
@@ -658,8 +660,12 @@
     Primitive::Type type = Primitive::kPrimNot;
     DCHECK(locations->CanCall());
     DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(out_.reg()));
-    DCHECK(!instruction_->IsInvoke() ||
-           (instruction_->IsInvokeStaticOrDirect() &&
+    DCHECK(instruction_->IsInstanceFieldGet() ||
+           instruction_->IsStaticFieldGet() ||
+           instruction_->IsArrayGet() ||
+           instruction_->IsInstanceOf() ||
+           instruction_->IsCheckCast() ||
+           ((instruction_->IsInvokeStaticOrDirect() || instruction_->IsInvokeVirtual()) &&
             instruction_->GetLocations()->Intrinsified()))
         << "Unexpected instruction in read barrier for heap reference slow path: "
         << instruction_->DebugName();
@@ -677,7 +683,7 @@
     // introduce a copy of it, `index`.
     Location index = index_;
     if (index_.IsValid()) {
-      // Handle `index_` for HArrayGet and intrinsic UnsafeGetObject.
+      // Handle `index_` for HArrayGet and UnsafeGetObject/UnsafeGetObjectVolatile intrinsics.
       if (instruction_->IsArrayGet()) {
         // Compute the actual memory offset and store it in `index`.
         Register index_reg = RegisterFrom(index_, Primitive::kPrimInt);
@@ -725,7 +731,11 @@
             "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
         __ Add(index_reg, index_reg, Operand(offset_));
       } else {
-        DCHECK(instruction_->IsInvoke());
+        // In the case of the UnsafeGetObject/UnsafeGetObjectVolatile
+        // intrinsics, `index_` is not shifted by a scale factor of 2
+        // (as in the case of ArrayGet), as it is actually an offset
+        // to an object field within an object.
+        DCHECK(instruction_->IsInvoke()) << instruction_->DebugName();
         DCHECK(instruction_->GetLocations()->Intrinsified());
         DCHECK((instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObject) ||
                (instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObjectVolatile))
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index a21c295..54ca9a4 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -444,7 +444,9 @@
            instruction_->IsLoadClass() ||
            instruction_->IsLoadString() ||
            instruction_->IsInstanceOf() ||
-           instruction_->IsCheckCast())
+           instruction_->IsCheckCast() ||
+           ((instruction_->IsInvokeStaticOrDirect() || instruction_->IsInvokeVirtual()) &&
+            instruction_->GetLocations()->Intrinsified()))
         << "Unexpected instruction in read barrier marking slow path: "
         << instruction_->DebugName();
 
@@ -507,8 +509,12 @@
     Register reg_out = out_.AsRegister<Register>();
     DCHECK(locations->CanCall());
     DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(reg_out));
-    DCHECK(!instruction_->IsInvoke() ||
-           (instruction_->IsInvokeStaticOrDirect() &&
+    DCHECK(instruction_->IsInstanceFieldGet() ||
+           instruction_->IsStaticFieldGet() ||
+           instruction_->IsArrayGet() ||
+           instruction_->IsInstanceOf() ||
+           instruction_->IsCheckCast() ||
+           ((instruction_->IsInvokeStaticOrDirect() || instruction_->IsInvokeVirtual()) &&
             instruction_->GetLocations()->Intrinsified()))
         << "Unexpected instruction in read barrier for heap reference slow path: "
         << instruction_->DebugName();
@@ -521,7 +527,7 @@
     // introduce a copy of it, `index`.
     Location index = index_;
     if (index_.IsValid()) {
-      // Handle `index_` for HArrayGet and intrinsic UnsafeGetObject.
+      // Handle `index_` for HArrayGet and UnsafeGetObject/UnsafeGetObjectVolatile intrinsics.
       if (instruction_->IsArrayGet()) {
         // Compute the actual memory offset and store it in `index`.
         Register index_reg = index_.AsRegister<Register>();
@@ -569,7 +575,11 @@
             "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
         __ AddImmediate(index_reg, Immediate(offset_));
       } else {
-        DCHECK(instruction_->IsInvoke());
+        // In the case of the UnsafeGetObject/UnsafeGetObjectVolatile
+        // intrinsics, `index_` is not shifted by a scale factor of 2
+        // (as in the case of ArrayGet), as it is actually an offset
+        // to an object field within an object.
+        DCHECK(instruction_->IsInvoke()) << instruction_->DebugName();
         DCHECK(instruction_->GetLocations()->Intrinsified());
         DCHECK((instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObject) ||
                (instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObjectVolatile))
@@ -6853,6 +6863,9 @@
   DCHECK(kEmitCompilerReadBarrier);
   DCHECK(kUseBakerReadBarrier);
 
+  static_assert(
+      sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
+      "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
   // /* HeapReference<Object> */ ref =
   //     *(obj + data_offset + index * sizeof(HeapReference<Object>))
   Address src = index.IsConstant() ?
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 135f0c4..17532ba 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -465,7 +465,9 @@
            instruction_->IsLoadClass() ||
            instruction_->IsLoadString() ||
            instruction_->IsInstanceOf() ||
-           instruction_->IsCheckCast())
+           instruction_->IsCheckCast() ||
+           ((instruction_->IsInvokeStaticOrDirect() || instruction_->IsInvokeVirtual()) &&
+            instruction_->GetLocations()->Intrinsified()))
         << "Unexpected instruction in read barrier marking slow path: "
         << instruction_->DebugName();
 
@@ -528,8 +530,12 @@
     CpuRegister reg_out = out_.AsRegister<CpuRegister>();
     DCHECK(locations->CanCall());
     DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(reg_out.AsRegister())) << out_;
-    DCHECK(!instruction_->IsInvoke() ||
-           (instruction_->IsInvokeStaticOrDirect() &&
+    DCHECK(instruction_->IsInstanceFieldGet() ||
+           instruction_->IsStaticFieldGet() ||
+           instruction_->IsArrayGet() ||
+           instruction_->IsInstanceOf() ||
+           instruction_->IsCheckCast() ||
+           ((instruction_->IsInvokeStaticOrDirect() || instruction_->IsInvokeVirtual()) &&
             instruction_->GetLocations()->Intrinsified()))
         << "Unexpected instruction in read barrier for heap reference slow path: "
         << instruction_->DebugName();
@@ -542,7 +548,7 @@
     // introduce a copy of it, `index`.
     Location index = index_;
     if (index_.IsValid()) {
-      // Handle `index_` for HArrayGet and intrinsic UnsafeGetObject.
+      // Handle `index_` for HArrayGet and UnsafeGetObject/UnsafeGetObjectVolatile intrinsics.
       if (instruction_->IsArrayGet()) {
         // Compute real offset and store it in index_.
         Register index_reg = index_.AsRegister<CpuRegister>().AsRegister();
@@ -590,7 +596,11 @@
             "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
         __ AddImmediate(CpuRegister(index_reg), Immediate(offset_));
       } else {
-        DCHECK(instruction_->IsInvoke());
+        // In the case of the UnsafeGetObject/UnsafeGetObjectVolatile
+        // intrinsics, `index_` is not shifted by a scale factor of 2
+        // (as in the case of ArrayGet), as it is actually an offset
+        // to an object field within an object.
+        DCHECK(instruction_->IsInvoke()) << instruction_->DebugName();
         DCHECK(instruction_->GetLocations()->Intrinsified());
         DCHECK((instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObject) ||
                (instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObjectVolatile))
@@ -6317,6 +6327,9 @@
   DCHECK(kEmitCompilerReadBarrier);
   DCHECK(kUseBakerReadBarrier);
 
+  static_assert(
+      sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
+      "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
   // /* HeapReference<Object> */ ref =
   //     *(obj + data_offset + index * sizeof(HeapReference<Object>))
   Address src = index.IsConstant() ?
diff --git a/compiler/optimizing/intrinsics_arm.cc b/compiler/optimizing/intrinsics_arm.cc
index f094062..1fc9061 100644
--- a/compiler/optimizing/intrinsics_arm.cc
+++ b/compiler/optimizing/intrinsics_arm.cc
@@ -47,19 +47,6 @@
   if (res == nullptr) {
     return false;
   }
-  if (kEmitCompilerReadBarrier && res->CanCall()) {
-    // Generating an intrinsic for this HInvoke may produce an
-    // IntrinsicSlowPathARM slow path.  Currently this approach
-    // does not work when using read barriers, as the emitted
-    // calling sequence will make use of another slow path
-    // (ReadBarrierForRootSlowPathARM for HInvokeStaticOrDirect,
-    // ReadBarrierSlowPathARM for HInvokeVirtual).  So we bail
-    // out in this case.
-    //
-    // TODO: Find a way to have intrinsics work with read barriers.
-    invoke->SetLocations(nullptr);
-    return false;
-  }
   return res->Intrinsified();
 }
 
@@ -920,9 +907,10 @@
   // The UnsafeCASObject intrinsic is missing a read barrier, and
   // therefore sometimes does not work as expected (b/25883050).
   // Turn it off temporarily as a quick fix, until the read barrier is
-  // implemented (see TODO in GenCAS below).
+  // implemented (see TODO in GenCAS).
   //
-  // TODO(rpl): Fix this issue and re-enable this intrinsic with read barriers.
+  // TODO(rpl): Implement read barrier support in GenCAS and re-enable
+  // this intrinsic.
   if (kEmitCompilerReadBarrier) {
     return;
   }
@@ -933,6 +921,15 @@
   GenCas(invoke->GetLocations(), Primitive::kPrimInt, codegen_);
 }
 void IntrinsicCodeGeneratorARM::VisitUnsafeCASObject(HInvoke* invoke) {
+  // The UnsafeCASObject intrinsic is missing a read barrier, and
+  // therefore sometimes does not work as expected (b/25883050).
+  // Turn it off temporarily as a quick fix, until the read barrier is
+  // implemented (see TODO in GenCAS).
+  //
+  // TODO(rpl): Implement read barrier support in GenCAS and re-enable
+  // this intrinsic.
+  DCHECK(!kEmitCompilerReadBarrier);
+
   GenCas(invoke->GetLocations(), Primitive::kPrimNot, codegen_);
 }
 
@@ -1385,6 +1382,12 @@
 }
 
 void IntrinsicLocationsBuilderARM::VisitSystemArrayCopy(HInvoke* invoke) {
+  // TODO(rpl): Implement read barriers in the SystemArrayCopy
+  // intrinsic and re-enable it (b/29516905).
+  if (kEmitCompilerReadBarrier) {
+    return;
+  }
+
   CodeGenerator::CreateSystemArrayCopyLocationSummary(invoke);
   LocationSummary* locations = invoke->GetLocations();
   if (locations == nullptr) {
@@ -1469,11 +1472,11 @@
   }
 }
 
-// TODO: Implement read barriers in the SystemArrayCopy intrinsic.
-// Note that this code path is not used (yet) because we do not
-// intrinsify methods that can go into the IntrinsicSlowPathARM
-// slow path.
 void IntrinsicCodeGeneratorARM::VisitSystemArrayCopy(HInvoke* invoke) {
+  // TODO(rpl): Implement read barriers in the SystemArrayCopy
+  // intrinsic and re-enable it (b/29516905).
+  DCHECK(!kEmitCompilerReadBarrier);
+
   ArmAssembler* assembler = GetAssembler();
   LocationSummary* locations = invoke->GetLocations();
 
diff --git a/compiler/optimizing/intrinsics_arm64.cc b/compiler/optimizing/intrinsics_arm64.cc
index 12d65be..ee10506 100644
--- a/compiler/optimizing/intrinsics_arm64.cc
+++ b/compiler/optimizing/intrinsics_arm64.cc
@@ -149,19 +149,6 @@
   if (res == nullptr) {
     return false;
   }
-  if (kEmitCompilerReadBarrier && res->CanCall()) {
-    // Generating an intrinsic for this HInvoke may produce an
-    // IntrinsicSlowPathARM64 slow path.  Currently this approach
-    // does not work when using read barriers, as the emitted
-    // calling sequence will make use of another slow path
-    // (ReadBarrierForRootSlowPathARM64 for HInvokeStaticOrDirect,
-    // ReadBarrierSlowPathARM64 for HInvokeVirtual).  So we bail
-    // out in this case.
-    //
-    // TODO: Find a way to have intrinsics work with read barriers.
-    invoke->SetLocations(nullptr);
-    return false;
-  }
   return res->Intrinsified();
 }
 
@@ -1110,9 +1097,10 @@
   // The UnsafeCASObject intrinsic is missing a read barrier, and
   // therefore sometimes does not work as expected (b/25883050).
   // Turn it off temporarily as a quick fix, until the read barrier is
-  // implemented (see TODO in GenCAS below).
+  // implemented (see TODO in GenCAS).
   //
-  // TODO(rpl): Fix this issue and re-enable this intrinsic with read barriers.
+  // TODO(rpl): Implement read barrier support in GenCAS and re-enable
+  // this intrinsic.
   if (kEmitCompilerReadBarrier) {
     return;
   }
@@ -1127,6 +1115,15 @@
   GenCas(invoke->GetLocations(), Primitive::kPrimLong, codegen_);
 }
 void IntrinsicCodeGeneratorARM64::VisitUnsafeCASObject(HInvoke* invoke) {
+  // The UnsafeCASObject intrinsic is missing a read barrier, and
+  // therefore sometimes does not work as expected (b/25883050).
+  // Turn it off temporarily as a quick fix, until the read barrier is
+  // implemented (see TODO in GenCAS).
+  //
+  // TODO(rpl): Implement read barrier support in GenCAS and re-enable
+  // this intrinsic.
+  DCHECK(!kEmitCompilerReadBarrier);
+
   GenCas(invoke->GetLocations(), Primitive::kPrimNot, codegen_);
 }
 
@@ -2070,6 +2067,12 @@
 // We want to use two temporary registers in order to reduce the register pressure in arm64.
 // So we don't use the CodeGenerator::CreateSystemArrayCopyLocationSummary.
 void IntrinsicLocationsBuilderARM64::VisitSystemArrayCopy(HInvoke* invoke) {
+  // TODO(rpl): Implement read barriers in the SystemArrayCopy
+  // intrinsic and re-enable it (b/29516905).
+  if (kEmitCompilerReadBarrier) {
+    return;
+  }
+
   // Check to see if we have known failures that will cause us to have to bail out
   // to the runtime, and just generate the runtime call directly.
   HIntConstant* src_pos = invoke->InputAt(1)->AsIntConstant();
@@ -2122,6 +2125,10 @@
 }
 
 void IntrinsicCodeGeneratorARM64::VisitSystemArrayCopy(HInvoke* invoke) {
+  // TODO(rpl): Implement read barriers in the SystemArrayCopy
+  // intrinsic and re-enable it (b/29516905).
+  DCHECK(!kEmitCompilerReadBarrier);
+
   vixl::MacroAssembler* masm = GetVIXLAssembler();
   LocationSummary* locations = invoke->GetLocations();
 
diff --git a/compiler/optimizing/intrinsics_x86.cc b/compiler/optimizing/intrinsics_x86.cc
index 31911aa..a657194 100644
--- a/compiler/optimizing/intrinsics_x86.cc
+++ b/compiler/optimizing/intrinsics_x86.cc
@@ -60,19 +60,6 @@
   if (res == nullptr) {
     return false;
   }
-  if (kEmitCompilerReadBarrier && res->CanCall()) {
-    // Generating an intrinsic for this HInvoke may produce an
-    // IntrinsicSlowPathX86 slow path.  Currently this approach
-    // does not work when using read barriers, as the emitted
-    // calling sequence will make use of another slow path
-    // (ReadBarrierForRootSlowPathX86 for HInvokeStaticOrDirect,
-    // ReadBarrierSlowPathX86 for HInvokeVirtual).  So we bail
-    // out in this case.
-    //
-    // TODO: Find a way to have intrinsics work with read barriers.
-    invoke->SetLocations(nullptr);
-    return false;
-  }
   return res->Intrinsified();
 }
 
@@ -1921,12 +1908,13 @@
     if (is_volatile) {
       // Need to use XMM to read volatile.
       locations->AddTemp(Location::RequiresFpuRegister());
-      locations->SetOut(Location::RequiresRegister());
+      locations->SetOut(Location::RequiresRegister(), Location::kNoOutputOverlap);
     } else {
       locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
     }
   } else {
-    locations->SetOut(Location::RequiresRegister());
+    locations->SetOut(Location::RequiresRegister(),
+                      can_call ? Location::kOutputOverlap : Location::kNoOutputOverlap);
   }
   if (type == Primitive::kPrimNot && kEmitCompilerReadBarrier && kUseBakerReadBarrier) {
     // We need a temporary register for the read barrier marking slow
@@ -2152,9 +2140,9 @@
   // The UnsafeCASObject intrinsic is missing a read barrier, and
   // therefore sometimes does not work as expected (b/25883050).
   // Turn it off temporarily as a quick fix, until the read barrier is
-  // implemented.
+  // implemented (see TODO in GenCAS).
   //
-  // TODO(rpl): Implement a read barrier in GenCAS below and re-enable
+  // TODO(rpl): Implement read barrier support in GenCAS and re-enable
   // this intrinsic.
   if (kEmitCompilerReadBarrier) {
     return;
@@ -2279,6 +2267,15 @@
 }
 
 void IntrinsicCodeGeneratorX86::VisitUnsafeCASObject(HInvoke* invoke) {
+  // The UnsafeCASObject intrinsic is missing a read barrier, and
+  // therefore sometimes does not work as expected (b/25883050).
+  // Turn it off temporarily as a quick fix, until the read barrier is
+  // implemented (see TODO in GenCAS).
+  //
+  // TODO(rpl): Implement read barrier support in GenCAS and re-enable
+  // this intrinsic.
+  DCHECK(!kEmitCompilerReadBarrier);
+
   GenCAS(Primitive::kPrimNot, invoke, codegen_);
 }
 
diff --git a/compiler/optimizing/intrinsics_x86_64.cc b/compiler/optimizing/intrinsics_x86_64.cc
index 504e746..57e4bdd 100644
--- a/compiler/optimizing/intrinsics_x86_64.cc
+++ b/compiler/optimizing/intrinsics_x86_64.cc
@@ -54,19 +54,6 @@
   if (res == nullptr) {
     return false;
   }
-  if (kEmitCompilerReadBarrier && res->CanCall()) {
-    // Generating an intrinsic for this HInvoke may produce an
-    // IntrinsicSlowPathX86_64 slow path.  Currently this approach
-    // does not work when using read barriers, as the emitted
-    // calling sequence will make use of another slow path
-    // (ReadBarrierForRootSlowPathX86_64 for HInvokeStaticOrDirect,
-    // ReadBarrierSlowPathX86_64 for HInvokeVirtual).  So we bail
-    // out in this case.
-    //
-    // TODO: Find a way to have intrinsics work with read barriers.
-    invoke->SetLocations(nullptr);
-    return false;
-  }
   return res->Intrinsified();
 }
 
@@ -1122,14 +1109,20 @@
 
 
 void IntrinsicLocationsBuilderX86_64::VisitSystemArrayCopy(HInvoke* invoke) {
+  // TODO(rpl): Implement read barriers in the SystemArrayCopy
+  // intrinsic and re-enable it (b/29516905).
+  if (kEmitCompilerReadBarrier) {
+    return;
+  }
+
   CodeGenerator::CreateSystemArrayCopyLocationSummary(invoke);
 }
 
-// TODO: Implement read barriers in the SystemArrayCopy intrinsic.
-// Note that this code path is not used (yet) because we do not
-// intrinsify methods that can go into the IntrinsicSlowPathX86_64
-// slow path.
 void IntrinsicCodeGeneratorX86_64::VisitSystemArrayCopy(HInvoke* invoke) {
+  // TODO(rpl): Implement read barriers in the SystemArrayCopy
+  // intrinsic and re-enable it (b/29516905).
+  DCHECK(!kEmitCompilerReadBarrier);
+
   X86_64Assembler* assembler = GetAssembler();
   LocationSummary* locations = invoke->GetLocations();
 
@@ -1992,7 +1985,8 @@
   locations->SetInAt(0, Location::NoLocation());        // Unused receiver.
   locations->SetInAt(1, Location::RequiresRegister());
   locations->SetInAt(2, Location::RequiresRegister());
-  locations->SetOut(Location::RequiresRegister());
+  locations->SetOut(Location::RequiresRegister(),
+                    can_call ? Location::kOutputOverlap : Location::kNoOutputOverlap);
   if (type == Primitive::kPrimNot && kEmitCompilerReadBarrier && kUseBakerReadBarrier) {
     // We need a temporary register for the read barrier marking slow
     // path in InstructionCodeGeneratorX86_64::GenerateReferenceLoadWithBakerReadBarrier.
@@ -2179,9 +2173,9 @@
   // The UnsafeCASObject intrinsic is missing a read barrier, and
   // therefore sometimes does not work as expected (b/25883050).
   // Turn it off temporarily as a quick fix, until the read barrier is
-  // implemented.
+  // implemented (see TODO in GenCAS).
   //
-  // TODO(rpl): Implement a read barrier in GenCAS below and re-enable
+  // TODO(rpl): Implement read barrier support in GenCAS and re-enable
   // this intrinsic.
   if (kEmitCompilerReadBarrier) {
     return;
@@ -2297,6 +2291,15 @@
 }
 
 void IntrinsicCodeGeneratorX86_64::VisitUnsafeCASObject(HInvoke* invoke) {
+  // The UnsafeCASObject intrinsic is missing a read barrier, and
+  // therefore sometimes does not work as expected (b/25883050).
+  // Turn it off temporarily as a quick fix, until the read barrier is
+  // implemented (see TODO in GenCAS).
+  //
+  // TODO(rpl): Implement read barrier support in GenCAS and re-enable
+  // this intrinsic.
+  DCHECK(!kEmitCompilerReadBarrier);
+
   GenCAS(Primitive::kPrimNot, invoke, codegen_);
 }
 
diff --git a/compiler/optimizing/locations.h b/compiler/optimizing/locations.h
index 63bbc2c..3f27c91 100644
--- a/compiler/optimizing/locations.h
+++ b/compiler/optimizing/locations.h
@@ -38,7 +38,13 @@
 class Location : public ValueObject {
  public:
   enum OutputOverlap {
+    // The liveness of the output overlaps the liveness of one or
+    // several input(s); the register allocator cannot reuse an
+    // input's location for the output's location.
     kOutputOverlap,
+    // The liveness of the output does not overlap the liveness of any
+    // input; the register allocator is allowed to reuse an input's
+    // location for the output's location.
     kNoOutputOverlap
   };
 
@@ -494,6 +500,10 @@
     return inputs_.size();
   }
 
+  // Set the output location.  Argument `overlaps` tells whether the
+  // output overlaps any of the inputs (if so, it cannot share the
+  // same register as one of the inputs); it is set to
+  // `Location::kOutputOverlap` by default for safety.
   void SetOut(Location location, Location::OutputOverlap overlaps = Location::kOutputOverlap) {
     DCHECK(output_.IsInvalid());
     output_overlaps_ = overlaps;
diff --git a/test/004-UnsafeTest/src/Main.java b/test/004-UnsafeTest/src/Main.java
index b2f905e..9d4618a 100644
--- a/test/004-UnsafeTest/src/Main.java
+++ b/test/004-UnsafeTest/src/Main.java
@@ -39,16 +39,24 @@
     }
   }
 
-  private static Unsafe getUnsafe() throws Exception {
+  private static Unsafe getUnsafe() throws NoSuchFieldException, IllegalAccessException {
     Class<?> unsafeClass = Unsafe.class;
     Field f = unsafeClass.getDeclaredField("theUnsafe");
     f.setAccessible(true);
     return (Unsafe) f.get(null);
   }
 
-  public static void main(String[] args) throws Exception {
+  public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException {
     System.loadLibrary(args[0]);
     Unsafe unsafe = getUnsafe();
+
+    testArrayBaseOffset(unsafe);
+    testArrayIndexScale(unsafe);
+    testGetAndPutAndCAS(unsafe);
+    testGetAndPutVolatile(unsafe);
+  }
+
+  private static void testArrayBaseOffset(Unsafe unsafe) {
     check(unsafe.arrayBaseOffset(boolean[].class), vmArrayBaseOffset(boolean[].class),
         "Unsafe.arrayBaseOffset(boolean[])");
     check(unsafe.arrayBaseOffset(byte[].class), vmArrayBaseOffset(byte[].class),
@@ -65,7 +73,9 @@
         "Unsafe.arrayBaseOffset(long[])");
     check(unsafe.arrayBaseOffset(Object[].class), vmArrayBaseOffset(Object[].class),
         "Unsafe.arrayBaseOffset(Object[])");
+  }
 
+  private static void testArrayIndexScale(Unsafe unsafe) {
     check(unsafe.arrayIndexScale(boolean[].class), vmArrayIndexScale(boolean[].class),
         "Unsafe.arrayIndexScale(boolean[])");
     check(unsafe.arrayIndexScale(byte[].class), vmArrayIndexScale(byte[].class),
@@ -82,7 +92,9 @@
         "Unsafe.arrayIndexScale(long[])");
     check(unsafe.arrayIndexScale(Object[].class), vmArrayIndexScale(Object[].class),
         "Unsafe.arrayIndexScale(Object[])");
+  }
 
+  private static void testGetAndPutAndCAS(Unsafe unsafe) throws NoSuchFieldException {
     TestClass t = new TestClass();
 
     int intValue = 12345678;
@@ -185,12 +197,58 @@
     }
   }
 
+  private static void testGetAndPutVolatile(Unsafe unsafe) throws NoSuchFieldException {
+    TestVolatileClass tv = new TestVolatileClass();
+
+    int intValue = 12345678;
+    Field volatileIntField = TestVolatileClass.class.getDeclaredField("volatileIntVar");
+    long volatileIntOffset = unsafe.objectFieldOffset(volatileIntField);
+    check(unsafe.getIntVolatile(tv, volatileIntOffset),
+          0,
+          "Unsafe.getIntVolatile(Object, long) - initial");
+    unsafe.putIntVolatile(tv, volatileIntOffset, intValue);
+    check(tv.volatileIntVar, intValue, "Unsafe.putIntVolatile(Object, long, int)");
+    check(unsafe.getIntVolatile(tv, volatileIntOffset),
+          intValue,
+          "Unsafe.getIntVolatile(Object, long)");
+
+    long longValue = 1234567887654321L;
+    Field volatileLongField = TestVolatileClass.class.getDeclaredField("volatileLongVar");
+    long volatileLongOffset = unsafe.objectFieldOffset(volatileLongField);
+    check(unsafe.getLongVolatile(tv, volatileLongOffset),
+          0,
+          "Unsafe.getLongVolatile(Object, long) - initial");
+    unsafe.putLongVolatile(tv, volatileLongOffset, longValue);
+    check(tv.volatileLongVar, longValue, "Unsafe.putLongVolatile(Object, long, long)");
+    check(unsafe.getLongVolatile(tv, volatileLongOffset),
+          longValue,
+          "Unsafe.getLongVolatile(Object, long)");
+
+    Object objectValue = new Object();
+    Field volatileObjectField = TestVolatileClass.class.getDeclaredField("volatileObjectVar");
+    long volatileObjectOffset = unsafe.objectFieldOffset(volatileObjectField);
+    check(unsafe.getObjectVolatile(tv, volatileObjectOffset),
+          null,
+          "Unsafe.getObjectVolatile(Object, long) - initial");
+    unsafe.putObjectVolatile(tv, volatileObjectOffset, objectValue);
+    check(tv.volatileObjectVar, objectValue, "Unsafe.putObjectVolatile(Object, long, Object)");
+    check(unsafe.getObjectVolatile(tv, volatileObjectOffset),
+          objectValue,
+          "Unsafe.getObjectVolatile(Object, long)");
+  }
+
   private static class TestClass {
     public int intVar = 0;
     public long longVar = 0;
     public Object objectVar = null;
   }
 
+  private static class TestVolatileClass {
+    public volatile int volatileIntVar = 0;
+    public volatile long volatileLongVar = 0;
+    public volatile Object volatileObjectVar = null;
+  }
+
   private static native int vmArrayBaseOffset(Class clazz);
   private static native int vmArrayIndexScale(Class clazz);
 }