ARM read barrier support for concurrent GC in Optimizing.
This first implementation uses slow paths to instrument heap
reference loads and GC root loads for the concurrent copying
collector, respectively calling the artReadBarrierSlow and
artReadBarrierForRootSlow runtime entry points.
Notes:
- This implementation does not instrument HInvokeVirtual
nor HInvokeInterface instructions (for class reference
loads), as the corresponding read barriers are not stricly
required with the current concurrent copying collector.
- Intrinsics which may eventually call (on slow path) are
disabled when read barriers are enabled, as the current
slow path infrastructure does not support this case.
- When read barriers are enabled, the code generated for a
HArraySet instruction always go into the array set slow
path for object arrays (delegating the operation to the
runtime), as we are lacking a mechanism to keep a
temporary register live accross a runtime call (needed for
the instrumentation of type checking code, which requires
two successive read barriers).
Bug: 12687968
Change-Id: I92e8db414d029f952c07f3d3a98069e46dfdbc2a
diff --git a/compiler/common_compiler_test.h b/compiler/common_compiler_test.h
index a121f8b..7b0e5af 100644
--- a/compiler/common_compiler_test.h
+++ b/compiler/common_compiler_test.h
@@ -128,6 +128,7 @@
#define TEST_DISABLED_FOR_READ_BARRIER_WITH_OPTIMIZING_FOR_UNSUPPORTED_INSTRUCTION_SETS() \
if (kUseReadBarrier && GetCompilerKind() == Compiler::kOptimizing) { \
switch (GetInstructionSet()) { \
+ case kThumb2: \
case kX86: \
case kX86_64: \
/* Instruction set has read barrier support. */ \
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 655bbb8..12ab68e 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -34,6 +34,9 @@
namespace art {
+template<class MirrorType>
+class GcRoot;
+
namespace arm {
static bool ExpectedPairLayout(Location location) {
@@ -286,15 +289,6 @@
CodeGeneratorARM* arm_codegen = down_cast<CodeGeneratorARM*>(codegen);
__ Bind(GetEntryLabel());
- if (instruction_->IsCheckCast()) {
- // The codegen for the instruction overwrites `temp`, so put it back in place.
- Register obj = locations->InAt(0).AsRegister<Register>();
- Register temp = locations->GetTemp(0).AsRegister<Register>();
- uint32_t class_offset = mirror::Object::ClassOffset().Int32Value();
- __ LoadFromOffset(kLoadWord, temp, obj, class_offset);
- __ MaybeUnpoisonHeapReference(temp);
- }
-
if (!is_fatal_) {
SaveLiveRegisters(codegen, locations);
}
@@ -315,6 +309,8 @@
instruction_,
instruction_->GetDexPc(),
this);
+ CheckEntrypointTypes<
+ kQuickInstanceofNonTrivial, uint32_t, const mirror::Class*, const mirror::Class*>();
arm_codegen->Move32(locations->Out(), Location::RegisterLocation(R0));
} else {
DCHECK(instruction_->IsCheckCast());
@@ -322,6 +318,7 @@
instruction_,
instruction_->GetDexPc(),
this);
+ CheckEntrypointTypes<kQuickCheckCast, void, const mirror::Class*, const mirror::Class*>();
}
if (!is_fatal_) {
@@ -408,6 +405,221 @@
DISALLOW_COPY_AND_ASSIGN(ArraySetSlowPathARM);
};
+// Slow path generating a read barrier for a heap reference.
+class ReadBarrierForHeapReferenceSlowPathARM : public SlowPathCode {
+ public:
+ ReadBarrierForHeapReferenceSlowPathARM(HInstruction* instruction,
+ Location out,
+ Location ref,
+ Location obj,
+ uint32_t offset,
+ Location index)
+ : instruction_(instruction),
+ out_(out),
+ ref_(ref),
+ obj_(obj),
+ offset_(offset),
+ index_(index) {
+ DCHECK(kEmitCompilerReadBarrier);
+ // If `obj` is equal to `out` or `ref`, it means the initial object
+ // has been overwritten by (or after) the heap object reference load
+ // to be instrumented, e.g.:
+ //
+ // __ LoadFromOffset(kLoadWord, out, out, offset);
+ // codegen_->GenerateReadBarrier(instruction, out_loc, out_loc, out_loc, offset);
+ //
+ // In that case, we have lost the information about the original
+ // object, and the emitted read barrier cannot work properly.
+ DCHECK(!obj.Equals(out)) << "obj=" << obj << " out=" << out;
+ DCHECK(!obj.Equals(ref)) << "obj=" << obj << " ref=" << ref;
+ }
+
+ void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
+ CodeGeneratorARM* arm_codegen = down_cast<CodeGeneratorARM*>(codegen);
+ LocationSummary* locations = instruction_->GetLocations();
+ Register reg_out = out_.AsRegister<Register>();
+ DCHECK(locations->CanCall());
+ DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(reg_out));
+ DCHECK(!instruction_->IsInvoke() ||
+ (instruction_->IsInvokeStaticOrDirect() &&
+ instruction_->GetLocations()->Intrinsified()));
+
+ __ Bind(GetEntryLabel());
+ SaveLiveRegisters(codegen, locations);
+
+ // We may have to change the index's value, but as `index_` is a
+ // constant member (like other "inputs" of this slow path),
+ // introduce a copy of it, `index`.
+ Location index = index_;
+ if (index_.IsValid()) {
+ // Handle `index_` for HArrayGet and intrinsic UnsafeGetObject.
+ if (instruction_->IsArrayGet()) {
+ // Compute the actual memory offset and store it in `index`.
+ Register index_reg = index_.AsRegister<Register>();
+ DCHECK(locations->GetLiveRegisters()->ContainsCoreRegister(index_reg));
+ if (codegen->IsCoreCalleeSaveRegister(index_reg)) {
+ // We are about to change the value of `index_reg` (see the
+ // calls to art::arm::Thumb2Assembler::Lsl and
+ // art::arm::Thumb2Assembler::AddConstant below), but it has
+ // not been saved by the previous call to
+ // art::SlowPathCode::SaveLiveRegisters, as it is a
+ // callee-save register --
+ // art::SlowPathCode::SaveLiveRegisters does not consider
+ // callee-save registers, as it has been designed with the
+ // assumption that callee-save registers are supposed to be
+ // handled by the called function. So, as a callee-save
+ // register, `index_reg` _would_ eventually be saved onto
+ // the stack, but it would be too late: we would have
+ // changed its value earlier. Therefore, we manually save
+ // it here into another freely available register,
+ // `free_reg`, chosen of course among the caller-save
+ // registers (as a callee-save `free_reg` register would
+ // exhibit the same problem).
+ //
+ // Note we could have requested a temporary register from
+ // the register allocator instead; but we prefer not to, as
+ // this is a slow path, and we know we can find a
+ // caller-save register that is available.
+ Register free_reg = FindAvailableCallerSaveRegister(codegen);
+ __ Mov(free_reg, index_reg);
+ index_reg = free_reg;
+ index = Location::RegisterLocation(index_reg);
+ } else {
+ // The initial register stored in `index_` has already been
+ // saved in the call to art::SlowPathCode::SaveLiveRegisters
+ // (as it is not a callee-save register), so we can freely
+ // use it.
+ }
+ // Shifting the index value contained in `index_reg` by the scale
+ // factor (2) cannot overflow in practice, as the runtime is
+ // unable to allocate object arrays with a size larger than
+ // 2^26 - 1 (that is, 2^28 - 4 bytes).
+ __ Lsl(index_reg, index_reg, TIMES_4);
+ static_assert(
+ sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
+ "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
+ __ AddConstant(index_reg, index_reg, offset_);
+ } else {
+ DCHECK(instruction_->IsInvoke());
+ DCHECK(instruction_->GetLocations()->Intrinsified());
+ DCHECK((instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObject) ||
+ (instruction_->AsInvoke()->GetIntrinsic() == Intrinsics::kUnsafeGetObjectVolatile))
+ << instruction_->AsInvoke()->GetIntrinsic();
+ DCHECK_EQ(offset_, 0U);
+ DCHECK(index_.IsRegisterPair());
+ // UnsafeGet's offset location is a register pair, the low
+ // part contains the correct offset.
+ index = index_.ToLow();
+ }
+ }
+
+ // We're moving two or three locations to locations that could
+ // overlap, so we need a parallel move resolver.
+ InvokeRuntimeCallingConvention calling_convention;
+ HParallelMove parallel_move(codegen->GetGraph()->GetArena());
+ parallel_move.AddMove(ref_,
+ Location::RegisterLocation(calling_convention.GetRegisterAt(0)),
+ Primitive::kPrimNot,
+ nullptr);
+ parallel_move.AddMove(obj_,
+ Location::RegisterLocation(calling_convention.GetRegisterAt(1)),
+ Primitive::kPrimNot,
+ nullptr);
+ if (index.IsValid()) {
+ parallel_move.AddMove(index,
+ Location::RegisterLocation(calling_convention.GetRegisterAt(2)),
+ Primitive::kPrimInt,
+ nullptr);
+ codegen->GetMoveResolver()->EmitNativeCode(¶llel_move);
+ } else {
+ codegen->GetMoveResolver()->EmitNativeCode(¶llel_move);
+ __ LoadImmediate(calling_convention.GetRegisterAt(2), offset_);
+ }
+ arm_codegen->InvokeRuntime(QUICK_ENTRY_POINT(pReadBarrierSlow),
+ instruction_,
+ instruction_->GetDexPc(),
+ this);
+ CheckEntrypointTypes<
+ kQuickReadBarrierSlow, mirror::Object*, mirror::Object*, mirror::Object*, uint32_t>();
+ arm_codegen->Move32(out_, Location::RegisterLocation(R0));
+
+ RestoreLiveRegisters(codegen, locations);
+ __ b(GetExitLabel());
+ }
+
+ const char* GetDescription() const OVERRIDE { return "ReadBarrierForHeapReferenceSlowPathARM"; }
+
+ private:
+ Register FindAvailableCallerSaveRegister(CodeGenerator* codegen) {
+ size_t ref = static_cast<int>(ref_.AsRegister<Register>());
+ size_t obj = static_cast<int>(obj_.AsRegister<Register>());
+ for (size_t i = 0, e = codegen->GetNumberOfCoreRegisters(); i < e; ++i) {
+ if (i != ref && i != obj && !codegen->IsCoreCalleeSaveRegister(i)) {
+ return static_cast<Register>(i);
+ }
+ }
+ // We shall never fail to find a free caller-save register, as
+ // there are more than two core caller-save registers on ARM
+ // (meaning it is possible to find one which is different from
+ // `ref` and `obj`).
+ DCHECK_GT(codegen->GetNumberOfCoreCallerSaveRegisters(), 2u);
+ LOG(FATAL) << "Could not find a free caller-save register";
+ UNREACHABLE();
+ }
+
+ HInstruction* const instruction_;
+ const Location out_;
+ const Location ref_;
+ const Location obj_;
+ const uint32_t offset_;
+ // An additional location containing an index to an array.
+ // Only used for HArrayGet and the UnsafeGetObject &
+ // UnsafeGetObjectVolatile intrinsics.
+ const Location index_;
+
+ DISALLOW_COPY_AND_ASSIGN(ReadBarrierForHeapReferenceSlowPathARM);
+};
+
+// Slow path generating a read barrier for a GC root.
+class ReadBarrierForRootSlowPathARM : public SlowPathCode {
+ public:
+ ReadBarrierForRootSlowPathARM(HInstruction* instruction, Location out, Location root)
+ : instruction_(instruction), out_(out), root_(root) {}
+
+ void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
+ LocationSummary* locations = instruction_->GetLocations();
+ Register reg_out = out_.AsRegister<Register>();
+ DCHECK(locations->CanCall());
+ DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(reg_out));
+ DCHECK(instruction_->IsLoadClass() || instruction_->IsLoadString());
+
+ __ Bind(GetEntryLabel());
+ SaveLiveRegisters(codegen, locations);
+
+ InvokeRuntimeCallingConvention calling_convention;
+ CodeGeneratorARM* arm_codegen = down_cast<CodeGeneratorARM*>(codegen);
+ arm_codegen->Move32(Location::RegisterLocation(calling_convention.GetRegisterAt(0)), root_);
+ arm_codegen->InvokeRuntime(QUICK_ENTRY_POINT(pReadBarrierForRootSlow),
+ instruction_,
+ instruction_->GetDexPc(),
+ this);
+ CheckEntrypointTypes<kQuickReadBarrierForRootSlow, mirror::Object*, GcRoot<mirror::Object>*>();
+ arm_codegen->Move32(out_, Location::RegisterLocation(R0));
+
+ RestoreLiveRegisters(codegen, locations);
+ __ b(GetExitLabel());
+ }
+
+ const char* GetDescription() const OVERRIDE { return "ReadBarrierForRootSlowPathARM"; }
+
+ private:
+ HInstruction* const instruction_;
+ const Location out_;
+ const Location root_;
+
+ DISALLOW_COPY_AND_ASSIGN(ReadBarrierForRootSlowPathARM);
+};
+
#undef __
#define __ down_cast<ArmAssembler*>(GetAssembler())->
@@ -581,7 +793,7 @@
LOG(FATAL) << "Unreachable type " << type;
}
- return Location();
+ return Location::NoLocation();
}
void CodeGeneratorARM::SetupBlockedRegisters(bool is_baseline) const {
@@ -820,7 +1032,7 @@
LOG(FATAL) << "Unexpected parameter type " << type;
break;
}
- return Location();
+ return Location::NoLocation();
}
Location InvokeDexCallingConventionVisitorARM::GetReturnLocation(Primitive::Type type) const {
@@ -847,7 +1059,7 @@
}
case Primitive::kPrimVoid:
- return Location();
+ return Location::NoLocation();
}
UNREACHABLE();
@@ -1762,29 +1974,39 @@
void InstructionCodeGeneratorARM::VisitInvokeInterface(HInvokeInterface* invoke) {
// TODO: b/18116999, our IMTs can miss an IncompatibleClassChangeError.
- Register temp = invoke->GetLocations()->GetTemp(0).AsRegister<Register>();
+ LocationSummary* locations = invoke->GetLocations();
+ Register temp = locations->GetTemp(0).AsRegister<Register>();
+ Register hidden_reg = locations->GetTemp(1).AsRegister<Register>();
uint32_t method_offset = mirror::Class::EmbeddedImTableEntryOffset(
invoke->GetImtIndex() % mirror::Class::kImtSize, kArmPointerSize).Uint32Value();
- LocationSummary* locations = invoke->GetLocations();
Location receiver = locations->InAt(0);
uint32_t class_offset = mirror::Object::ClassOffset().Int32Value();
- // Set the hidden argument.
- __ LoadImmediate(invoke->GetLocations()->GetTemp(1).AsRegister<Register>(),
- invoke->GetDexMethodIndex());
+ // Set the hidden argument. This is safe to do this here, as R12
+ // won't be modified thereafter, before the `blx` (call) instruction.
+ DCHECK_EQ(R12, hidden_reg);
+ __ LoadImmediate(hidden_reg, invoke->GetDexMethodIndex());
- // temp = object->GetClass();
if (receiver.IsStackSlot()) {
__ LoadFromOffset(kLoadWord, temp, SP, receiver.GetStackIndex());
+ // /* HeapReference<Class> */ temp = temp->klass_
__ LoadFromOffset(kLoadWord, temp, temp, class_offset);
} else {
+ // /* HeapReference<Class> */ temp = receiver->klass_
__ LoadFromOffset(kLoadWord, temp, receiver.AsRegister<Register>(), class_offset);
}
codegen_->MaybeRecordImplicitNullCheck(invoke);
+ // Instead of simply (possibly) unpoisoning `temp` here, we should
+ // emit a read barrier for the previous class reference load.
+ // However this is not required in practice, as this is an
+ // intermediate/temporary reference and because the current
+ // concurrent copying collector keeps the from-space memory
+ // intact/accessible until the end of the marking phase (the
+ // concurrent copying collector may not in the future).
__ MaybeUnpoisonHeapReference(temp);
// temp = temp->GetImtEntryAt(method_offset);
- uint32_t entry_point = ArtMethod::EntryPointFromQuickCompiledCodeOffset(
- kArmWordSize).Int32Value();
+ uint32_t entry_point =
+ ArtMethod::EntryPointFromQuickCompiledCodeOffset(kArmWordSize).Int32Value();
__ LoadFromOffset(kLoadWord, temp, temp, method_offset);
// LR = temp->GetEntryPoint();
__ LoadFromOffset(kLoadWord, LR, temp, entry_point);
@@ -3407,6 +3629,9 @@
Register out_lo,
Register out_hi) {
if (offset != 0) {
+ // Ensure `out_lo` is different from `addr`, so that loading
+ // `offset` into `out_lo` does not clutter `addr`.
+ DCHECK_NE(out_lo, addr);
__ LoadImmediate(out_lo, offset);
__ add(IP, addr, ShifterOperand(out_lo));
addr = IP;
@@ -3594,14 +3819,26 @@
void LocationsBuilderARM::HandleFieldGet(HInstruction* instruction, const FieldInfo& field_info) {
DCHECK(instruction->IsInstanceFieldGet() || instruction->IsStaticFieldGet());
+
+ bool object_field_get_with_read_barrier =
+ kEmitCompilerReadBarrier && (field_info.GetFieldType() == Primitive::kPrimNot);
LocationSummary* locations =
- new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
+ new (GetGraph()->GetArena()) LocationSummary(instruction,
+ object_field_get_with_read_barrier ?
+ LocationSummary::kCallOnSlowPath :
+ LocationSummary::kNoCall);
locations->SetInAt(0, Location::RequiresRegister());
bool volatile_for_double = field_info.IsVolatile()
&& (field_info.GetFieldType() == Primitive::kPrimDouble)
&& !codegen_->GetInstructionSetFeatures().HasAtomicLdrdAndStrd();
- bool overlap = field_info.IsVolatile() && (field_info.GetFieldType() == Primitive::kPrimLong);
+ // The output overlaps in case of volatile long: we don't want the
+ // code generated by GenerateWideAtomicLoad to overwrite the
+ // object's location. Likewise, in the case of an object field get
+ // with read barriers enabled, we do not want the load to overwrite
+ // the object's location, as we need it to emit the read barrier.
+ bool overlap = (field_info.IsVolatile() && (field_info.GetFieldType() == Primitive::kPrimLong)) ||
+ object_field_get_with_read_barrier;
if (Primitive::IsFloatingPointType(instruction->GetType())) {
locations->SetOut(Location::RequiresFpuRegister());
@@ -3667,7 +3904,8 @@
DCHECK(instruction->IsInstanceFieldGet() || instruction->IsStaticFieldGet());
LocationSummary* locations = instruction->GetLocations();
- Register base = locations->InAt(0).AsRegister<Register>();
+ Location base_loc = locations->InAt(0);
+ Register base = base_loc.AsRegister<Register>();
Location out = locations->Out();
bool is_volatile = field_info.IsVolatile();
bool atomic_ldrd_strd = codegen_->GetInstructionSetFeatures().HasAtomicLdrdAndStrd();
@@ -3747,7 +3985,7 @@
}
if (field_type == Primitive::kPrimNot) {
- __ MaybeUnpoisonHeapReference(out.AsRegister<Register>());
+ codegen_->MaybeGenerateReadBarrier(instruction, out, out, base_loc, offset);
}
}
@@ -3891,20 +4129,31 @@
}
void LocationsBuilderARM::VisitArrayGet(HArrayGet* instruction) {
+ bool object_array_get_with_read_barrier =
+ kEmitCompilerReadBarrier && (instruction->GetType() == Primitive::kPrimNot);
LocationSummary* locations =
- new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
+ new (GetGraph()->GetArena()) LocationSummary(instruction,
+ object_array_get_with_read_barrier ?
+ LocationSummary::kCallOnSlowPath :
+ LocationSummary::kNoCall);
locations->SetInAt(0, Location::RequiresRegister());
locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
if (Primitive::IsFloatingPointType(instruction->GetType())) {
locations->SetOut(Location::RequiresFpuRegister(), Location::kNoOutputOverlap);
} else {
- locations->SetOut(Location::RequiresRegister(), Location::kNoOutputOverlap);
+ // The output overlaps in the case of an object array get with
+ // read barriers enabled: we do not want the move to overwrite the
+ // array's location, as we need it to emit the read barrier.
+ locations->SetOut(
+ Location::RequiresRegister(),
+ object_array_get_with_read_barrier ? Location::kOutputOverlap : Location::kNoOutputOverlap);
}
}
void InstructionCodeGeneratorARM::VisitArrayGet(HArrayGet* instruction) {
LocationSummary* locations = instruction->GetLocations();
- Register obj = locations->InAt(0).AsRegister<Register>();
+ Location obj_loc = locations->InAt(0);
+ Register obj = obj_loc.AsRegister<Register>();
Location index = locations->InAt(1);
Primitive::Type type = instruction->GetType();
@@ -3967,8 +4216,9 @@
case Primitive::kPrimInt:
case Primitive::kPrimNot: {
- static_assert(sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
- "art::mirror::HeapReference<mirror::Object> and int32_t have different sizes.");
+ static_assert(
+ sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
+ "art::mirror::HeapReference<mirror::Object> and int32_t have different sizes.");
uint32_t data_offset = mirror::Array::DataOffset(sizeof(int32_t)).Uint32Value();
Register out = locations->Out().AsRegister<Register>();
if (index.IsConstant()) {
@@ -4031,8 +4281,17 @@
codegen_->MaybeRecordImplicitNullCheck(instruction);
if (type == Primitive::kPrimNot) {
- Register out = locations->Out().AsRegister<Register>();
- __ MaybeUnpoisonHeapReference(out);
+ static_assert(
+ sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
+ "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
+ uint32_t data_offset = mirror::Array::DataOffset(sizeof(int32_t)).Uint32Value();
+ Location out = locations->Out();
+ if (index.IsConstant()) {
+ uint32_t offset = (index.GetConstant()->AsIntConstant()->GetValue() << TIMES_4) + data_offset;
+ codegen_->MaybeGenerateReadBarrier(instruction, out, out, obj_loc, offset);
+ } else {
+ codegen_->MaybeGenerateReadBarrier(instruction, out, out, obj_loc, data_offset, index);
+ }
}
}
@@ -4041,11 +4300,16 @@
bool needs_write_barrier =
CodeGenerator::StoreNeedsWriteBarrier(value_type, instruction->GetValue());
- bool may_need_runtime_call = instruction->NeedsTypeCheck();
+ bool may_need_runtime_call_for_type_check = instruction->NeedsTypeCheck();
+ bool object_array_set_with_read_barrier =
+ kEmitCompilerReadBarrier && (value_type == Primitive::kPrimNot);
LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(
instruction,
- may_need_runtime_call ? LocationSummary::kCallOnSlowPath : LocationSummary::kNoCall);
+ (may_need_runtime_call_for_type_check || object_array_set_with_read_barrier) ?
+ LocationSummary::kCallOnSlowPath :
+ LocationSummary::kNoCall);
+
locations->SetInAt(0, Location::RequiresRegister());
locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
if (Primitive::IsFloatingPointType(value_type)) {
@@ -4053,20 +4317,20 @@
} else {
locations->SetInAt(2, Location::RequiresRegister());
}
-
if (needs_write_barrier) {
// Temporary registers for the write barrier.
locations->AddTemp(Location::RequiresRegister()); // Possibly used for ref. poisoning too.
- locations->AddTemp(Location::RequiresRegister());
+ locations->AddTemp(Location::RequiresRegister()); // Possibly used for read barrier too.
}
}
void InstructionCodeGeneratorARM::VisitArraySet(HArraySet* instruction) {
LocationSummary* locations = instruction->GetLocations();
- Register array = locations->InAt(0).AsRegister<Register>();
+ Location array_loc = locations->InAt(0);
+ Register array = array_loc.AsRegister<Register>();
Location index = locations->InAt(1);
Primitive::Type value_type = instruction->GetComponentType();
- bool may_need_runtime_call = locations->CanCall();
+ bool may_need_runtime_call_for_type_check = instruction->NeedsTypeCheck();
bool needs_write_barrier =
CodeGenerator::StoreNeedsWriteBarrier(value_type, instruction->GetValue());
@@ -4103,7 +4367,8 @@
case Primitive::kPrimNot: {
uint32_t data_offset = mirror::Array::DataOffset(sizeof(int32_t)).Uint32Value();
- Register value = locations->InAt(2).AsRegister<Register>();
+ Location value_loc = locations->InAt(2);
+ Register value = value_loc.AsRegister<Register>();
Register source = value;
if (instruction->InputAt(2)->IsNullConstant()) {
@@ -4117,6 +4382,8 @@
__ add(IP, array, ShifterOperand(index.AsRegister<Register>(), LSL, TIMES_4));
__ StoreToOffset(kStoreWord, source, IP, data_offset);
}
+ DCHECK(!needs_write_barrier);
+ DCHECK(!may_need_runtime_call_for_type_check);
break;
}
@@ -4129,7 +4396,7 @@
Label done;
SlowPathCode* slow_path = nullptr;
- if (may_need_runtime_call) {
+ if (may_need_runtime_call_for_type_check) {
slow_path = new (GetGraph()->GetArena()) ArraySetSlowPathARM(instruction);
codegen_->AddSlowPath(slow_path);
if (instruction->GetValueCanBeNull()) {
@@ -4149,23 +4416,63 @@
__ Bind(&non_zero);
}
- __ LoadFromOffset(kLoadWord, temp1, array, class_offset);
- codegen_->MaybeRecordImplicitNullCheck(instruction);
- __ MaybeUnpoisonHeapReference(temp1);
- __ LoadFromOffset(kLoadWord, temp1, temp1, component_offset);
- __ LoadFromOffset(kLoadWord, temp2, value, class_offset);
- // No need to poison/unpoison, we're comparing two poisoined references.
- __ cmp(temp1, ShifterOperand(temp2));
- if (instruction->StaticTypeOfArrayIsObjectArray()) {
- Label do_put;
- __ b(&do_put, EQ);
- __ MaybeUnpoisonHeapReference(temp1);
- __ LoadFromOffset(kLoadWord, temp1, temp1, super_offset);
- // No need to poison/unpoison, we're comparing against null.
- __ CompareAndBranchIfNonZero(temp1, slow_path->GetEntryLabel());
- __ Bind(&do_put);
+ if (kEmitCompilerReadBarrier) {
+ // When read barriers are enabled, the type checking
+ // instrumentation requires two read barriers:
+ //
+ // __ Mov(temp2, temp1);
+ // // /* HeapReference<Class> */ temp1 = temp1->component_type_
+ // __ LoadFromOffset(kLoadWord, temp1, temp1, component_offset);
+ // codegen_->GenerateReadBarrier(
+ // instruction, temp1_loc, temp1_loc, temp2_loc, component_offset);
+ //
+ // // /* HeapReference<Class> */ temp2 = value->klass_
+ // __ LoadFromOffset(kLoadWord, temp2, value, class_offset);
+ // codegen_->GenerateReadBarrier(
+ // instruction, temp2_loc, temp2_loc, value_loc, class_offset, temp1_loc);
+ //
+ // __ cmp(temp1, ShifterOperand(temp2));
+ //
+ // However, the second read barrier may trash `temp`, as it
+ // is a temporary register, and as such would not be saved
+ // along with live registers before calling the runtime (nor
+ // restored afterwards). So in this case, we bail out and
+ // delegate the work to the array set slow path.
+ //
+ // TODO: Extend the register allocator to support a new
+ // "(locally) live temp" location so as to avoid always
+ // going into the slow path when read barriers are enabled.
+ __ b(slow_path->GetEntryLabel());
} else {
- __ b(slow_path->GetEntryLabel(), NE);
+ // /* HeapReference<Class> */ temp1 = array->klass_
+ __ LoadFromOffset(kLoadWord, temp1, array, class_offset);
+ codegen_->MaybeRecordImplicitNullCheck(instruction);
+ __ MaybeUnpoisonHeapReference(temp1);
+
+ // /* HeapReference<Class> */ temp1 = temp1->component_type_
+ __ LoadFromOffset(kLoadWord, temp1, temp1, component_offset);
+ // /* HeapReference<Class> */ temp2 = value->klass_
+ __ LoadFromOffset(kLoadWord, temp2, value, class_offset);
+ // If heap poisoning is enabled, no need to unpoison `temp1`
+ // nor `temp2`, as we are comparing two poisoned references.
+ __ cmp(temp1, ShifterOperand(temp2));
+
+ if (instruction->StaticTypeOfArrayIsObjectArray()) {
+ Label do_put;
+ __ b(&do_put, EQ);
+ // If heap poisoning is enabled, the `temp1` reference has
+ // not been unpoisoned yet; unpoison it now.
+ __ MaybeUnpoisonHeapReference(temp1);
+
+ // /* HeapReference<Class> */ temp1 = temp1->super_class_
+ __ LoadFromOffset(kLoadWord, temp1, temp1, super_offset);
+ // If heap poisoning is enabled, no need to unpoison
+ // `temp1`, as we are comparing against null below.
+ __ CompareAndBranchIfNonZero(temp1, slow_path->GetEntryLabel());
+ __ Bind(&do_put);
+ } else {
+ __ b(slow_path->GetEntryLabel(), NE);
+ }
}
}
@@ -4189,7 +4496,7 @@
__ StoreToOffset(kStoreWord, source, IP, data_offset);
}
- if (!may_need_runtime_call) {
+ if (!may_need_runtime_call_for_type_check) {
codegen_->MaybeRecordImplicitNullCheck(instruction);
}
@@ -4618,7 +4925,8 @@
CodeGenerator::CreateLoadClassLocationSummary(
cls,
Location::RegisterLocation(calling_convention.GetRegisterAt(0)),
- Location::RegisterLocation(R0));
+ Location::RegisterLocation(R0),
+ /* code_generator_supports_read_barrier */ true);
}
void InstructionCodeGeneratorARM::VisitLoadClass(HLoadClass* cls) {
@@ -4632,21 +4940,42 @@
return;
}
- Register out = locations->Out().AsRegister<Register>();
+ Location out_loc = locations->Out();
+ Register out = out_loc.AsRegister<Register>();
Register current_method = locations->InAt(0).AsRegister<Register>();
+
if (cls->IsReferrersClass()) {
DCHECK(!cls->CanCallRuntime());
DCHECK(!cls->MustGenerateClinitCheck());
- __ LoadFromOffset(
- kLoadWord, out, current_method, ArtMethod::DeclaringClassOffset().Int32Value());
+ uint32_t declaring_class_offset = ArtMethod::DeclaringClassOffset().Int32Value();
+ if (kEmitCompilerReadBarrier) {
+ // /* GcRoot<mirror::Class>* */ out = &(current_method->declaring_class_)
+ __ AddConstant(out, current_method, declaring_class_offset);
+ // /* mirror::Class* */ out = out->Read()
+ codegen_->GenerateReadBarrierForRoot(cls, out_loc, out_loc);
+ } else {
+ // /* GcRoot<mirror::Class> */ out = current_method->declaring_class_
+ __ LoadFromOffset(kLoadWord, out, current_method, declaring_class_offset);
+ }
} else {
DCHECK(cls->CanCallRuntime());
+ // /* GcRoot<mirror::Class>[] */ out =
+ // current_method.ptr_sized_fields_->dex_cache_resolved_types_
__ LoadFromOffset(kLoadWord,
out,
current_method,
ArtMethod::DexCacheResolvedTypesOffset(kArmPointerSize).Int32Value());
- __ LoadFromOffset(kLoadWord, out, out, CodeGenerator::GetCacheOffset(cls->GetTypeIndex()));
- // TODO: We will need a read barrier here.
+
+ size_t cache_offset = CodeGenerator::GetCacheOffset(cls->GetTypeIndex());
+ if (kEmitCompilerReadBarrier) {
+ // /* GcRoot<mirror::Class>* */ out = &out[type_index]
+ __ AddConstant(out, out, cache_offset);
+ // /* mirror::Class* */ out = out->Read()
+ codegen_->GenerateReadBarrierForRoot(cls, out_loc, out_loc);
+ } else {
+ // /* GcRoot<mirror::Class> */ out = out[type_index]
+ __ LoadFromOffset(kLoadWord, out, out, cache_offset);
+ }
SlowPathCode* slow_path = new (GetGraph()->GetArena()) LoadClassSlowPathARM(
cls, cls, cls->GetDexPc(), cls->MustGenerateClinitCheck());
@@ -4701,13 +5030,35 @@
codegen_->AddSlowPath(slow_path);
LocationSummary* locations = load->GetLocations();
- Register out = locations->Out().AsRegister<Register>();
+ Location out_loc = locations->Out();
+ Register out = out_loc.AsRegister<Register>();
Register current_method = locations->InAt(0).AsRegister<Register>();
- __ LoadFromOffset(
- kLoadWord, out, current_method, ArtMethod::DeclaringClassOffset().Int32Value());
+
+ uint32_t declaring_class_offset = ArtMethod::DeclaringClassOffset().Int32Value();
+ if (kEmitCompilerReadBarrier) {
+ // /* GcRoot<mirror::Class>* */ out = &(current_method->declaring_class_)
+ __ AddConstant(out, current_method, declaring_class_offset);
+ // /* mirror::Class* */ out = out->Read()
+ codegen_->GenerateReadBarrierForRoot(load, out_loc, out_loc);
+ } else {
+ // /* GcRoot<mirror::Class> */ out = current_method->declaring_class_
+ __ LoadFromOffset(kLoadWord, out, current_method, declaring_class_offset);
+ }
+
+ // /* GcRoot<mirror::String>[] */ out = out->dex_cache_strings_
__ LoadFromOffset(kLoadWord, out, out, mirror::Class::DexCacheStringsOffset().Int32Value());
- __ LoadFromOffset(kLoadWord, out, out, CodeGenerator::GetCacheOffset(load->GetStringIndex()));
- // TODO: We will need a read barrier here.
+
+ size_t cache_offset = CodeGenerator::GetCacheOffset(load->GetStringIndex());
+ if (kEmitCompilerReadBarrier) {
+ // /* GcRoot<mirror::String>* */ out = &out[string_index]
+ __ AddConstant(out, out, cache_offset);
+ // /* mirror::String* */ out = out->Read()
+ codegen_->GenerateReadBarrierForRoot(load, out_loc, out_loc);
+ } else {
+ // /* GcRoot<mirror::String> */ out = out[string_index]
+ __ LoadFromOffset(kLoadWord, out, out, cache_offset);
+ }
+
__ CompareAndBranchIfZero(out, slow_path->GetEntryLabel());
__ Bind(slow_path->GetExitLabel());
}
@@ -4750,41 +5101,45 @@
void LocationsBuilderARM::VisitInstanceOf(HInstanceOf* instruction) {
LocationSummary::CallKind call_kind = LocationSummary::kNoCall;
- switch (instruction->GetTypeCheckKind()) {
+ TypeCheckKind type_check_kind = instruction->GetTypeCheckKind();
+ switch (type_check_kind) {
case TypeCheckKind::kExactCheck:
case TypeCheckKind::kAbstractClassCheck:
case TypeCheckKind::kClassHierarchyCheck:
case TypeCheckKind::kArrayObjectCheck:
- call_kind = LocationSummary::kNoCall;
- break;
- case TypeCheckKind::kUnresolvedCheck:
- case TypeCheckKind::kInterfaceCheck:
- call_kind = LocationSummary::kCall;
+ call_kind =
+ kEmitCompilerReadBarrier ? LocationSummary::kCallOnSlowPath : LocationSummary::kNoCall;
break;
case TypeCheckKind::kArrayCheck:
+ case TypeCheckKind::kUnresolvedCheck:
+ case TypeCheckKind::kInterfaceCheck:
call_kind = LocationSummary::kCallOnSlowPath;
break;
}
+
LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
- if (call_kind != LocationSummary::kCall) {
- locations->SetInAt(0, Location::RequiresRegister());
- locations->SetInAt(1, Location::RequiresRegister());
- // The out register is used as a temporary, so it overlaps with the inputs.
- // Note that TypeCheckSlowPathARM uses this register too.
- locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
- } else {
- InvokeRuntimeCallingConvention calling_convention;
- locations->SetInAt(1, Location::RegisterLocation(calling_convention.GetRegisterAt(0)));
- locations->SetInAt(0, Location::RegisterLocation(calling_convention.GetRegisterAt(1)));
- locations->SetOut(Location::RegisterLocation(R0));
+ locations->SetInAt(0, Location::RequiresRegister());
+ locations->SetInAt(1, Location::RequiresRegister());
+ // The "out" register is used as a temporary, so it overlaps with the inputs.
+ // Note that TypeCheckSlowPathARM uses this register too.
+ locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
+ // When read barriers are enabled, we need a temporary register for
+ // some cases.
+ if (kEmitCompilerReadBarrier &&
+ (type_check_kind == TypeCheckKind::kAbstractClassCheck ||
+ type_check_kind == TypeCheckKind::kClassHierarchyCheck ||
+ type_check_kind == TypeCheckKind::kArrayObjectCheck)) {
+ locations->AddTemp(Location::RequiresRegister());
}
}
void InstructionCodeGeneratorARM::VisitInstanceOf(HInstanceOf* instruction) {
LocationSummary* locations = instruction->GetLocations();
- Register obj = locations->InAt(0).AsRegister<Register>();
+ Location obj_loc = locations->InAt(0);
+ Register obj = obj_loc.AsRegister<Register>();
Register cls = locations->InAt(1).AsRegister<Register>();
- Register out = locations->Out().AsRegister<Register>();
+ Location out_loc = locations->Out();
+ Register out = out_loc.AsRegister<Register>();
uint32_t class_offset = mirror::Object::ClassOffset().Int32Value();
uint32_t super_offset = mirror::Class::SuperClassOffset().Int32Value();
uint32_t component_offset = mirror::Class::ComponentTypeOffset().Int32Value();
@@ -4798,15 +5153,9 @@
__ CompareAndBranchIfZero(obj, &zero);
}
- // In case of an interface/unresolved check, we put the object class into the object register.
- // This is safe, as the register is caller-save, and the object must be in another
- // register if it survives the runtime call.
- Register target = (instruction->GetTypeCheckKind() == TypeCheckKind::kInterfaceCheck) ||
- (instruction->GetTypeCheckKind() == TypeCheckKind::kUnresolvedCheck)
- ? obj
- : out;
- __ LoadFromOffset(kLoadWord, target, obj, class_offset);
- __ MaybeUnpoisonHeapReference(target);
+ // /* HeapReference<Class> */ out = obj->klass_
+ __ LoadFromOffset(kLoadWord, out, obj, class_offset);
+ codegen_->MaybeGenerateReadBarrier(instruction, out_loc, out_loc, obj_loc, class_offset);
switch (instruction->GetTypeCheckKind()) {
case TypeCheckKind::kExactCheck: {
@@ -4817,13 +5166,23 @@
__ b(&done);
break;
}
+
case TypeCheckKind::kAbstractClassCheck: {
// If the class is abstract, we eagerly fetch the super class of the
// object to avoid doing a comparison we know will fail.
Label loop;
__ Bind(&loop);
+ Location temp_loc = kEmitCompilerReadBarrier ? locations->GetTemp(0) : Location::NoLocation();
+ if (kEmitCompilerReadBarrier) {
+ // Save the value of `out` into `temp` before overwriting it
+ // in the following move operation, as we will need it for the
+ // read barrier below.
+ Register temp = temp_loc.AsRegister<Register>();
+ __ Mov(temp, out);
+ }
+ // /* HeapReference<Class> */ out = out->super_class_
__ LoadFromOffset(kLoadWord, out, out, super_offset);
- __ MaybeUnpoisonHeapReference(out);
+ codegen_->MaybeGenerateReadBarrier(instruction, out_loc, out_loc, temp_loc, super_offset);
// If `out` is null, we use it for the result, and jump to `done`.
__ CompareAndBranchIfZero(out, &done);
__ cmp(out, ShifterOperand(cls));
@@ -4834,14 +5193,24 @@
}
break;
}
+
case TypeCheckKind::kClassHierarchyCheck: {
// Walk over the class hierarchy to find a match.
Label loop, success;
__ Bind(&loop);
__ cmp(out, ShifterOperand(cls));
__ b(&success, EQ);
+ Location temp_loc = kEmitCompilerReadBarrier ? locations->GetTemp(0) : Location::NoLocation();
+ if (kEmitCompilerReadBarrier) {
+ // Save the value of `out` into `temp` before overwriting it
+ // in the following move operation, as we will need it for the
+ // read barrier below.
+ Register temp = temp_loc.AsRegister<Register>();
+ __ Mov(temp, out);
+ }
+ // /* HeapReference<Class> */ out = out->super_class_
__ LoadFromOffset(kLoadWord, out, out, super_offset);
- __ MaybeUnpoisonHeapReference(out);
+ codegen_->MaybeGenerateReadBarrier(instruction, out_loc, out_loc, temp_loc, super_offset);
__ CompareAndBranchIfNonZero(out, &loop);
// If `out` is null, we use it for the result, and jump to `done`.
__ b(&done);
@@ -4852,14 +5221,24 @@
}
break;
}
+
case TypeCheckKind::kArrayObjectCheck: {
// Do an exact check.
Label exact_check;
__ cmp(out, ShifterOperand(cls));
__ b(&exact_check, EQ);
- // Otherwise, we need to check that the object's class is a non primitive array.
+ // Otherwise, we need to check that the object's class is a non-primitive array.
+ Location temp_loc = kEmitCompilerReadBarrier ? locations->GetTemp(0) : Location::NoLocation();
+ if (kEmitCompilerReadBarrier) {
+ // Save the value of `out` into `temp` before overwriting it
+ // in the following move operation, as we will need it for the
+ // read barrier below.
+ Register temp = temp_loc.AsRegister<Register>();
+ __ Mov(temp, out);
+ }
+ // /* HeapReference<Class> */ out = out->component_type_
__ LoadFromOffset(kLoadWord, out, out, component_offset);
- __ MaybeUnpoisonHeapReference(out);
+ codegen_->MaybeGenerateReadBarrier(instruction, out_loc, out_loc, temp_loc, component_offset);
// If `out` is null, we use it for the result, and jump to `done`.
__ CompareAndBranchIfZero(out, &done);
__ LoadFromOffset(kLoadUnsignedHalfword, out, out, primitive_offset);
@@ -4870,11 +5249,12 @@
__ b(&done);
break;
}
+
case TypeCheckKind::kArrayCheck: {
__ cmp(out, ShifterOperand(cls));
DCHECK(locations->OnlyCallsOnSlowPath());
- slow_path = new (GetGraph()->GetArena()) TypeCheckSlowPathARM(
- instruction, /* is_fatal */ false);
+ slow_path = new (GetGraph()->GetArena()) TypeCheckSlowPathARM(instruction,
+ /* is_fatal */ false);
codegen_->AddSlowPath(slow_path);
__ b(slow_path->GetEntryLabel(), NE);
__ LoadImmediate(out, 1);
@@ -4883,13 +5263,25 @@
}
break;
}
+
case TypeCheckKind::kUnresolvedCheck:
- case TypeCheckKind::kInterfaceCheck:
- default: {
- codegen_->InvokeRuntime(QUICK_ENTRY_POINT(pInstanceofNonTrivial),
- instruction,
- instruction->GetDexPc(),
- nullptr);
+ case TypeCheckKind::kInterfaceCheck: {
+ // Note that we indeed only call on slow path, but we always go
+ // into the slow path for the unresolved & interface check
+ // cases.
+ //
+ // We cannot directly call the InstanceofNonTrivial runtime
+ // entry point without resorting to a type checking slow path
+ // here (i.e. by calling InvokeRuntime directly), as it would
+ // require to assign fixed registers for the inputs of this
+ // HInstanceOf instruction (following the runtime calling
+ // convention), which might be cluttered by the potential first
+ // read barrier emission at the beginning of this method.
+ DCHECK(locations->OnlyCallsOnSlowPath());
+ slow_path = new (GetGraph()->GetArena()) TypeCheckSlowPathARM(instruction,
+ /* is_fatal */ false);
+ codegen_->AddSlowPath(slow_path);
+ __ b(slow_path->GetEntryLabel());
if (zero.IsLinked()) {
__ b(&done);
}
@@ -4915,57 +5307,61 @@
LocationSummary::CallKind call_kind = LocationSummary::kNoCall;
bool throws_into_catch = instruction->CanThrowIntoCatchBlock();
- switch (instruction->GetTypeCheckKind()) {
+ TypeCheckKind type_check_kind = instruction->GetTypeCheckKind();
+ switch (type_check_kind) {
case TypeCheckKind::kExactCheck:
case TypeCheckKind::kAbstractClassCheck:
case TypeCheckKind::kClassHierarchyCheck:
case TypeCheckKind::kArrayObjectCheck:
- call_kind = throws_into_catch
- ? LocationSummary::kCallOnSlowPath
- : LocationSummary::kNoCall;
- break;
- case TypeCheckKind::kUnresolvedCheck:
- case TypeCheckKind::kInterfaceCheck:
- call_kind = LocationSummary::kCall;
+ call_kind = (throws_into_catch || kEmitCompilerReadBarrier) ?
+ LocationSummary::kCallOnSlowPath :
+ LocationSummary::kNoCall; // In fact, call on a fatal (non-returning) slow path.
break;
case TypeCheckKind::kArrayCheck:
+ case TypeCheckKind::kUnresolvedCheck:
+ case TypeCheckKind::kInterfaceCheck:
call_kind = LocationSummary::kCallOnSlowPath;
break;
}
- LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(
- instruction, call_kind);
- if (call_kind != LocationSummary::kCall) {
- locations->SetInAt(0, Location::RequiresRegister());
- locations->SetInAt(1, Location::RequiresRegister());
- // Note that TypeCheckSlowPathARM uses this register too.
+ LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
+ locations->SetInAt(0, Location::RequiresRegister());
+ locations->SetInAt(1, Location::RequiresRegister());
+ // Note that TypeCheckSlowPathARM uses this "temp" register too.
+ locations->AddTemp(Location::RequiresRegister());
+ // When read barriers are enabled, we need an additional temporary
+ // register for some cases.
+ if (kEmitCompilerReadBarrier &&
+ (type_check_kind == TypeCheckKind::kAbstractClassCheck ||
+ type_check_kind == TypeCheckKind::kClassHierarchyCheck ||
+ type_check_kind == TypeCheckKind::kArrayObjectCheck)) {
locations->AddTemp(Location::RequiresRegister());
- } else {
- InvokeRuntimeCallingConvention calling_convention;
- locations->SetInAt(1, Location::RegisterLocation(calling_convention.GetRegisterAt(0)));
- locations->SetInAt(0, Location::RegisterLocation(calling_convention.GetRegisterAt(1)));
}
}
void InstructionCodeGeneratorARM::VisitCheckCast(HCheckCast* instruction) {
LocationSummary* locations = instruction->GetLocations();
- Register obj = locations->InAt(0).AsRegister<Register>();
+ Location obj_loc = locations->InAt(0);
+ Register obj = obj_loc.AsRegister<Register>();
Register cls = locations->InAt(1).AsRegister<Register>();
- Register temp = locations->WillCall()
- ? Register(kNoRegister)
- : locations->GetTemp(0).AsRegister<Register>();
-
+ Location temp_loc = locations->GetTemp(0);
+ Register temp = temp_loc.AsRegister<Register>();
uint32_t class_offset = mirror::Object::ClassOffset().Int32Value();
uint32_t super_offset = mirror::Class::SuperClassOffset().Int32Value();
uint32_t component_offset = mirror::Class::ComponentTypeOffset().Int32Value();
uint32_t primitive_offset = mirror::Class::PrimitiveTypeOffset().Int32Value();
- SlowPathCode* slow_path = nullptr;
- if (!locations->WillCall()) {
- slow_path = new (GetGraph()->GetArena()) TypeCheckSlowPathARM(
- instruction, !locations->CanCall());
- codegen_->AddSlowPath(slow_path);
- }
+ TypeCheckKind type_check_kind = instruction->GetTypeCheckKind();
+ bool is_type_check_slow_path_fatal =
+ (type_check_kind == TypeCheckKind::kExactCheck ||
+ type_check_kind == TypeCheckKind::kAbstractClassCheck ||
+ type_check_kind == TypeCheckKind::kClassHierarchyCheck ||
+ type_check_kind == TypeCheckKind::kArrayObjectCheck) &&
+ !instruction->CanThrowIntoCatchBlock();
+ SlowPathCode* type_check_slow_path =
+ new (GetGraph()->GetArena()) TypeCheckSlowPathARM(instruction,
+ is_type_check_slow_path_fatal);
+ codegen_->AddSlowPath(type_check_slow_path);
Label done;
// Avoid null check if we know obj is not null.
@@ -4973,76 +5369,159 @@
__ CompareAndBranchIfZero(obj, &done);
}
- if (locations->WillCall()) {
- __ LoadFromOffset(kLoadWord, obj, obj, class_offset);
- __ MaybeUnpoisonHeapReference(obj);
- } else {
- __ LoadFromOffset(kLoadWord, temp, obj, class_offset);
- __ MaybeUnpoisonHeapReference(temp);
- }
+ // /* HeapReference<Class> */ temp = obj->klass_
+ __ LoadFromOffset(kLoadWord, temp, obj, class_offset);
+ codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
- switch (instruction->GetTypeCheckKind()) {
+ switch (type_check_kind) {
case TypeCheckKind::kExactCheck:
case TypeCheckKind::kArrayCheck: {
__ cmp(temp, ShifterOperand(cls));
// Jump to slow path for throwing the exception or doing a
// more involved array check.
- __ b(slow_path->GetEntryLabel(), NE);
+ __ b(type_check_slow_path->GetEntryLabel(), NE);
break;
}
+
case TypeCheckKind::kAbstractClassCheck: {
// If the class is abstract, we eagerly fetch the super class of the
// object to avoid doing a comparison we know will fail.
- Label loop;
+ Label loop, compare_classes;
__ Bind(&loop);
+ Location temp2_loc =
+ kEmitCompilerReadBarrier ? locations->GetTemp(1) : Location::NoLocation();
+ if (kEmitCompilerReadBarrier) {
+ // Save the value of `temp` into `temp2` before overwriting it
+ // in the following move operation, as we will need it for the
+ // read barrier below.
+ Register temp2 = temp2_loc.AsRegister<Register>();
+ __ Mov(temp2, temp);
+ }
+ // /* HeapReference<Class> */ temp = temp->super_class_
__ LoadFromOffset(kLoadWord, temp, temp, super_offset);
- __ MaybeUnpoisonHeapReference(temp);
- // Jump to the slow path to throw the exception.
- __ CompareAndBranchIfZero(temp, slow_path->GetEntryLabel());
+ codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, temp2_loc, super_offset);
+
+ // If the class reference currently in `temp` is not null, jump
+ // to the `compare_classes` label to compare it with the checked
+ // class.
+ __ CompareAndBranchIfNonZero(temp, &compare_classes);
+ // Otherwise, jump to the slow path to throw the exception.
+ //
+ // But before, move back the object's class into `temp` before
+ // going into the slow path, as it has been overwritten in the
+ // meantime.
+ // /* HeapReference<Class> */ temp = obj->klass_
+ __ LoadFromOffset(kLoadWord, temp, obj, class_offset);
+ codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ __ b(type_check_slow_path->GetEntryLabel());
+
+ __ Bind(&compare_classes);
__ cmp(temp, ShifterOperand(cls));
__ b(&loop, NE);
break;
}
+
case TypeCheckKind::kClassHierarchyCheck: {
// Walk over the class hierarchy to find a match.
Label loop;
__ Bind(&loop);
__ cmp(temp, ShifterOperand(cls));
__ b(&done, EQ);
+
+ Location temp2_loc =
+ kEmitCompilerReadBarrier ? locations->GetTemp(1) : Location::NoLocation();
+ if (kEmitCompilerReadBarrier) {
+ // Save the value of `temp` into `temp2` before overwriting it
+ // in the following move operation, as we will need it for the
+ // read barrier below.
+ Register temp2 = temp2_loc.AsRegister<Register>();
+ __ Mov(temp2, temp);
+ }
+ // /* HeapReference<Class> */ temp = temp->super_class_
__ LoadFromOffset(kLoadWord, temp, temp, super_offset);
- __ MaybeUnpoisonHeapReference(temp);
+ codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, temp2_loc, super_offset);
+
+ // If the class reference currently in `temp` is not null, jump
+ // back at the beginning of the loop.
__ CompareAndBranchIfNonZero(temp, &loop);
- // Jump to the slow path to throw the exception.
- __ b(slow_path->GetEntryLabel());
+ // Otherwise, jump to the slow path to throw the exception.
+ //
+ // But before, move back the object's class into `temp` before
+ // going into the slow path, as it has been overwritten in the
+ // meantime.
+ // /* HeapReference<Class> */ temp = obj->klass_
+ __ LoadFromOffset(kLoadWord, temp, obj, class_offset);
+ codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ __ b(type_check_slow_path->GetEntryLabel());
break;
}
+
case TypeCheckKind::kArrayObjectCheck: {
// Do an exact check.
+ Label check_non_primitive_component_type;
__ cmp(temp, ShifterOperand(cls));
__ b(&done, EQ);
- // Otherwise, we need to check that the object's class is a non primitive array.
+
+ // Otherwise, we need to check that the object's class is a non-primitive array.
+ Location temp2_loc =
+ kEmitCompilerReadBarrier ? locations->GetTemp(1) : Location::NoLocation();
+ if (kEmitCompilerReadBarrier) {
+ // Save the value of `temp` into `temp2` before overwriting it
+ // in the following move operation, as we will need it for the
+ // read barrier below.
+ Register temp2 = temp2_loc.AsRegister<Register>();
+ __ Mov(temp2, temp);
+ }
+ // /* HeapReference<Class> */ temp = temp->component_type_
__ LoadFromOffset(kLoadWord, temp, temp, component_offset);
- __ MaybeUnpoisonHeapReference(temp);
- __ CompareAndBranchIfZero(temp, slow_path->GetEntryLabel());
+ codegen_->MaybeGenerateReadBarrier(
+ instruction, temp_loc, temp_loc, temp2_loc, component_offset);
+
+ // If the component type is not null (i.e. the object is indeed
+ // an array), jump to label `check_non_primitive_component_type`
+ // to further check that this component type is not a primitive
+ // type.
+ __ CompareAndBranchIfNonZero(temp, &check_non_primitive_component_type);
+ // Otherwise, jump to the slow path to throw the exception.
+ //
+ // But before, move back the object's class into `temp` before
+ // going into the slow path, as it has been overwritten in the
+ // meantime.
+ // /* HeapReference<Class> */ temp = obj->klass_
+ __ LoadFromOffset(kLoadWord, temp, obj, class_offset);
+ codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ __ b(type_check_slow_path->GetEntryLabel());
+
+ __ Bind(&check_non_primitive_component_type);
__ LoadFromOffset(kLoadUnsignedHalfword, temp, temp, primitive_offset);
- static_assert(Primitive::kPrimNot == 0, "Expected 0 for kPrimNot");
- __ CompareAndBranchIfNonZero(temp, slow_path->GetEntryLabel());
+ static_assert(Primitive::kPrimNot == 0, "Expected 0 for art::Primitive::kPrimNot");
+ __ CompareAndBranchIfZero(temp, &done);
+ // Same comment as above regarding `temp` and the slow path.
+ // /* HeapReference<Class> */ temp = obj->klass_
+ __ LoadFromOffset(kLoadWord, temp, obj, class_offset);
+ codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ __ b(type_check_slow_path->GetEntryLabel());
break;
}
+
case TypeCheckKind::kUnresolvedCheck:
case TypeCheckKind::kInterfaceCheck:
- default:
- codegen_->InvokeRuntime(QUICK_ENTRY_POINT(pCheckCast),
- instruction,
- instruction->GetDexPc(),
- nullptr);
+ // We always go into the type check slow path for the unresolved &
+ // interface check cases.
+ //
+ // We cannot directly call the CheckCast runtime entry point
+ // without resorting to a type checking slow path here (i.e. by
+ // calling InvokeRuntime directly), as it would require to
+ // assign fixed registers for the inputs of this HInstanceOf
+ // instruction (following the runtime calling convention), which
+ // might be cluttered by the potential first read barrier
+ // emission at the beginning of this method.
+ __ b(type_check_slow_path->GetEntryLabel());
break;
}
__ Bind(&done);
- if (slow_path != nullptr) {
- __ Bind(slow_path->GetExitLabel());
- }
+ __ Bind(type_check_slow_path->GetExitLabel());
}
void LocationsBuilderARM::VisitMonitorOperation(HMonitorOperation* instruction) {
@@ -5216,6 +5695,82 @@
}
}
+void CodeGeneratorARM::GenerateReadBarrier(HInstruction* instruction,
+ Location out,
+ Location ref,
+ Location obj,
+ uint32_t offset,
+ Location index) {
+ DCHECK(kEmitCompilerReadBarrier);
+
+ // If heap poisoning is enabled, the unpoisoning of the loaded
+ // reference will be carried out by the runtime within the slow
+ // path.
+ //
+ // Note that `ref` currently does not get unpoisoned (when heap
+ // poisoning is enabled), which is alright as the `ref` argument is
+ // not used by the artReadBarrierSlow entry point.
+ //
+ // TODO: Unpoison `ref` when it is used by artReadBarrierSlow.
+ SlowPathCode* slow_path = new (GetGraph()->GetArena())
+ ReadBarrierForHeapReferenceSlowPathARM(instruction, out, ref, obj, offset, index);
+ AddSlowPath(slow_path);
+
+ // TODO: When read barrier has a fast path, add it here.
+ /* Currently the read barrier call is inserted after the original load.
+ * However, if we have a fast path, we need to perform the load of obj.LockWord *before* the
+ * original load. This load-load ordering is required by the read barrier.
+ * The fast path/slow path (for Baker's algorithm) should look like:
+ *
+ * bool isGray = obj.LockWord & kReadBarrierMask;
+ * lfence; // load fence or artificial data dependence to prevent load-load reordering
+ * ref = obj.field; // this is the original load
+ * if (isGray) {
+ * ref = Mark(ref); // ideally the slow path just does Mark(ref)
+ * }
+ */
+
+ __ b(slow_path->GetEntryLabel());
+ __ Bind(slow_path->GetExitLabel());
+}
+
+void CodeGeneratorARM::MaybeGenerateReadBarrier(HInstruction* instruction,
+ Location out,
+ Location ref,
+ Location obj,
+ uint32_t offset,
+ Location index) {
+ if (kEmitCompilerReadBarrier) {
+ // If heap poisoning is enabled, unpoisoning will be taken care of
+ // by the runtime within the slow path.
+ GenerateReadBarrier(instruction, out, ref, obj, offset, index);
+ } else if (kPoisonHeapReferences) {
+ __ UnpoisonHeapReference(out.AsRegister<Register>());
+ }
+}
+
+void CodeGeneratorARM::GenerateReadBarrierForRoot(HInstruction* instruction,
+ Location out,
+ Location root) {
+ DCHECK(kEmitCompilerReadBarrier);
+
+ // Note that GC roots are not affected by heap poisoning, so we do
+ // not need to do anything special for this here.
+ SlowPathCode* slow_path =
+ new (GetGraph()->GetArena()) ReadBarrierForRootSlowPathARM(instruction, out, root);
+ AddSlowPath(slow_path);
+
+ // TODO: Implement a fast path for ReadBarrierForRoot, performing
+ // the following operation (for Baker's algorithm):
+ //
+ // if (thread.tls32_.is_gc_marking) {
+ // root = Mark(root);
+ // }
+
+ __ b(slow_path->GetEntryLabel());
+ __ Bind(slow_path->GetExitLabel());
+}
+
HInvokeStaticOrDirect::DispatchInfo CodeGeneratorARM::GetSupportedInvokeStaticOrDirectDispatch(
const HInvokeStaticOrDirect::DispatchInfo& desired_dispatch_info,
MethodReference target_method) {
@@ -5299,10 +5854,11 @@
method_reg = reg;
__ LoadFromOffset(kLoadWord, reg, SP, kCurrentMethodStackOffset);
}
- // temp = current_method->dex_cache_resolved_methods_;
- __ LoadFromOffset(
- kLoadWord, reg, method_reg, ArtMethod::DexCacheResolvedMethodsOffset(
- kArmPointerSize).Int32Value());
+ // /* ArtMethod*[] */ temp = temp.ptr_sized_fields_->dex_cache_resolved_methods_;
+ __ LoadFromOffset(kLoadWord,
+ reg,
+ method_reg,
+ ArtMethod::DexCacheResolvedMethodsOffset(kArmPointerSize).Int32Value());
// temp = temp[index_in_cache]
uint32_t index_in_cache = invoke->GetTargetMethod().dex_method_index;
__ LoadFromOffset(kLoadWord, reg, reg, CodeGenerator::GetCachePointerOffset(index_in_cache));
@@ -5346,10 +5902,17 @@
LocationSummary* locations = invoke->GetLocations();
Location receiver = locations->InAt(0);
uint32_t class_offset = mirror::Object::ClassOffset().Int32Value();
- // temp = object->GetClass();
DCHECK(receiver.IsRegister());
+ // /* HeapReference<Class> */ temp = receiver->klass_
__ LoadFromOffset(kLoadWord, temp, receiver.AsRegister<Register>(), class_offset);
MaybeRecordImplicitNullCheck(invoke);
+ // Instead of simply (possibly) unpoisoning `temp` here, we should
+ // emit a read barrier for the previous class reference load.
+ // However this is not required in practice, as this is an
+ // intermediate/temporary reference and because the current
+ // concurrent copying collector keeps the from-space memory
+ // intact/accessible until the end of the marking phase (the
+ // concurrent copying collector may not in the future).
__ MaybeUnpoisonHeapReference(temp);
// temp = temp->GetMethodAt(method_offset);
uint32_t entry_point = ArtMethod::EntryPointFromQuickCompiledCodeOffset(
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 32bfe0f..89de4f8 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -373,6 +373,51 @@
void EmitLinkerPatches(ArenaVector<LinkerPatch>* linker_patches) OVERRIDE;
+ // Generate a read barrier for a heap reference within `instruction`.
+ //
+ // A read barrier for an object reference read from the heap is
+ // implemented as a call to the artReadBarrierSlow runtime entry
+ // point, which is passed the values in locations `ref`, `obj`, and
+ // `offset`:
+ //
+ // mirror::Object* artReadBarrierSlow(mirror::Object* ref,
+ // mirror::Object* obj,
+ // uint32_t offset);
+ //
+ // The `out` location contains the value returned by
+ // artReadBarrierSlow.
+ //
+ // When `index` is provided (i.e. for array accesses), the offset
+ // value passed to artReadBarrierSlow is adjusted to take `index`
+ // into account.
+ void GenerateReadBarrier(HInstruction* instruction,
+ Location out,
+ Location ref,
+ Location obj,
+ uint32_t offset,
+ Location index = Location::NoLocation());
+
+ // If read barriers are enabled, generate a read barrier for a heap reference.
+ // If heap poisoning is enabled, also unpoison the reference in `out`.
+ void MaybeGenerateReadBarrier(HInstruction* instruction,
+ Location out,
+ Location ref,
+ Location obj,
+ uint32_t offset,
+ Location index = Location::NoLocation());
+
+ // Generate a read barrier for a GC root within `instruction`.
+ //
+ // A read barrier for an object reference GC root is implemented as
+ // a call to the artReadBarrierForRootSlow runtime entry point,
+ // which is passed the value in location `root`:
+ //
+ // mirror::Object* artReadBarrierForRootSlow(GcRoot<mirror::Object>* root);
+ //
+ // The `out` location contains the value returned by
+ // artReadBarrierForRootSlow.
+ void GenerateReadBarrierForRoot(HInstruction* instruction, Location out, Location root);
+
private:
using MethodToLiteralMap = ArenaSafeMap<MethodReference, Literal*, MethodReferenceComparator>;
diff --git a/compiler/optimizing/intrinsics_arm.cc b/compiler/optimizing/intrinsics_arm.cc
index 0a5acc3..d2017da 100644
--- a/compiler/optimizing/intrinsics_arm.cc
+++ b/compiler/optimizing/intrinsics_arm.cc
@@ -44,7 +44,23 @@
bool IntrinsicLocationsBuilderARM::TryDispatch(HInvoke* invoke) {
Dispatch(invoke);
LocationSummary* res = invoke->GetLocations();
- return res != nullptr && res->Intrinsified();
+ 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();
}
#define __ assembler->
@@ -662,20 +678,23 @@
(type == Primitive::kPrimLong) ||
(type == Primitive::kPrimNot));
ArmAssembler* assembler = codegen->GetAssembler();
- Register base = locations->InAt(1).AsRegister<Register>(); // Object pointer.
- Register offset = locations->InAt(2).AsRegisterPairLow<Register>(); // Long offset, lo part only.
+ Location base_loc = locations->InAt(1);
+ Register base = base_loc.AsRegister<Register>(); // Object pointer.
+ Location offset_loc = locations->InAt(2);
+ Register offset = offset_loc.AsRegisterPairLow<Register>(); // Long offset, lo part only.
+ Location trg_loc = locations->Out();
if (type == Primitive::kPrimLong) {
- Register trg_lo = locations->Out().AsRegisterPairLow<Register>();
+ Register trg_lo = trg_loc.AsRegisterPairLow<Register>();
__ add(IP, base, ShifterOperand(offset));
if (is_volatile && !codegen->GetInstructionSetFeatures().HasAtomicLdrdAndStrd()) {
- Register trg_hi = locations->Out().AsRegisterPairHigh<Register>();
+ Register trg_hi = trg_loc.AsRegisterPairHigh<Register>();
__ ldrexd(trg_lo, trg_hi, IP);
} else {
__ ldrd(trg_lo, Address(IP));
}
} else {
- Register trg = locations->Out().AsRegister<Register>();
+ Register trg = trg_loc.AsRegister<Register>();
__ ldr(trg, Address(base, offset));
}
@@ -684,14 +703,18 @@
}
if (type == Primitive::kPrimNot) {
- Register trg = locations->Out().AsRegister<Register>();
- __ MaybeUnpoisonHeapReference(trg);
+ codegen->MaybeGenerateReadBarrier(invoke, trg_loc, trg_loc, base_loc, 0U, offset_loc);
}
}
static void CreateIntIntIntToIntLocations(ArenaAllocator* arena, HInvoke* invoke) {
+ bool can_call = kEmitCompilerReadBarrier &&
+ (invoke->GetIntrinsic() == Intrinsics::kUnsafeGetObject ||
+ invoke->GetIntrinsic() == Intrinsics::kUnsafeGetObjectVolatile);
LocationSummary* locations = new (arena) LocationSummary(invoke,
- LocationSummary::kNoCall,
+ can_call ?
+ LocationSummary::kCallOnSlowPath :
+ LocationSummary::kNoCall,
kIntrinsified);
locations->SetInAt(0, Location::NoLocation()); // Unused receiver.
locations->SetInAt(1, Location::RequiresRegister());
@@ -936,6 +959,7 @@
__ Bind(&loop_head);
__ ldrex(tmp_lo, tmp_ptr);
+ // TODO: Do we need a read barrier here when `type == Primitive::kPrimNot`?
__ subs(tmp_lo, tmp_lo, ShifterOperand(expected_lo));
@@ -964,7 +988,11 @@
// The UnsafeCASObject intrinsic does not always work when heap
// poisoning is enabled (it breaks run-test 004-UnsafeTest); turn it
// off temporarily as a quick fix.
+ //
// TODO(rpl): Fix it and turn it back on.
+ //
+ // TODO(rpl): Also, we should investigate whether we need a read
+ // barrier in the generated code.
if (kPoisonHeapReferences) {
return;
}
@@ -1400,6 +1428,10 @@
}
}
+// 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) {
ArmAssembler* assembler = GetAssembler();
LocationSummary* locations = invoke->GetLocations();
diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index 27ee472..2204921 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -383,10 +383,11 @@
|| instruction_set == kX86_64;
}
-// Read barrier are supported only on x86 and x86-64 at the moment.
+// Read barrier are supported only on ARM, x86 and x86-64 at the moment.
// TODO: Add support for other architectures and remove this function
static bool InstructionSetSupportsReadBarrier(InstructionSet instruction_set) {
- return instruction_set == kX86
+ return instruction_set == kThumb2
+ || instruction_set == kX86
|| instruction_set == kX86_64;
}
@@ -668,8 +669,8 @@
CompilerDriver* compiler_driver = GetCompilerDriver();
InstructionSet instruction_set = compiler_driver->GetInstructionSet();
- // Always use the thumb2 assembler: some runtime functionality (like implicit stack
- // overflow checks) assume thumb2.
+ // Always use the Thumb-2 assembler: some runtime functionality
+ // (like implicit stack overflow checks) assume Thumb-2.
if (instruction_set == kArm) {
instruction_set = kThumb2;
}
diff --git a/test/run-test b/test/run-test
index 10ec310..d0da34e 100755
--- a/test/run-test
+++ b/test/run-test
@@ -669,9 +669,9 @@
# -------------------------------
# Return whether the Optimizing compiler has read barrier support for ARCH.
function arch_supports_read_barrier() {
- # Optimizing has read barrier support for x86 and x86-64 at the
+ # Optimizing has read barrier support for ARM, x86 and x86-64 at the
# moment.
- [ "x$1" = xx86 ] || [ "x$1" = xx86_64 ]
+ [ "x$1" = xarm ] || [ "x$1" = xx86 ] || [ "x$1" = xx86_64 ]
}
# Tests named '<number>-checker-*' will also have their CFGs verified with