Revert "Revert "ARM64 Baker's read barrier fast path implementation.""
This reverts commit 28a2ff0bd6c30549f3f6465d8316f5707b1d072f.
Bug: 12687968
Change-Id: I6e25c70f303368629cdb1084f1d7039261cbb79a
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 2cb2741..6f5ce60 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -584,6 +584,56 @@
}
}
+// Slow path marking an object during a read barrier.
+class ReadBarrierMarkSlowPathARM64 : public SlowPathCodeARM64 {
+ public:
+ ReadBarrierMarkSlowPathARM64(HInstruction* instruction, Location out, Location obj)
+ : instruction_(instruction), out_(out), obj_(obj) {
+ DCHECK(kEmitCompilerReadBarrier);
+ }
+
+ const char* GetDescription() const OVERRIDE { return "ReadBarrierMarkSlowPathARM64"; }
+
+ void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
+ LocationSummary* locations = instruction_->GetLocations();
+ Primitive::Type type = Primitive::kPrimNot;
+ DCHECK(locations->CanCall());
+ DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(out_.reg()));
+ DCHECK(instruction_->IsInstanceFieldGet() ||
+ instruction_->IsStaticFieldGet() ||
+ instruction_->IsArrayGet() ||
+ instruction_->IsLoadClass() ||
+ instruction_->IsLoadString() ||
+ instruction_->IsInstanceOf() ||
+ instruction_->IsCheckCast())
+ << "Unexpected instruction in read barrier marking slow path: "
+ << instruction_->DebugName();
+
+ __ Bind(GetEntryLabel());
+ SaveLiveRegisters(codegen, locations);
+
+ InvokeRuntimeCallingConvention calling_convention;
+ CodeGeneratorARM64* arm64_codegen = down_cast<CodeGeneratorARM64*>(codegen);
+ arm64_codegen->MoveLocation(LocationFrom(calling_convention.GetRegisterAt(0)), obj_, type);
+ arm64_codegen->InvokeRuntime(QUICK_ENTRY_POINT(pReadBarrierMark),
+ instruction_,
+ instruction_->GetDexPc(),
+ this);
+ CheckEntrypointTypes<kQuickReadBarrierMark, mirror::Object*, mirror::Object*>();
+ arm64_codegen->MoveLocation(out_, calling_convention.GetReturnLocation(type), type);
+
+ RestoreLiveRegisters(codegen, locations);
+ __ B(GetExitLabel());
+ }
+
+ private:
+ HInstruction* const instruction_;
+ const Location out_;
+ const Location obj_;
+
+ DISALLOW_COPY_AND_ASSIGN(ReadBarrierMarkSlowPathARM64);
+};
+
// Slow path generating a read barrier for a heap reference.
class ReadBarrierForHeapReferenceSlowPathARM64 : public SlowPathCodeARM64 {
public:
@@ -605,7 +655,7 @@
// to be instrumented, e.g.:
//
// __ Ldr(out, HeapOperand(out, class_offset);
- // codegen_->GenerateReadBarrier(instruction, out_loc, out_loc, out_loc, offset);
+ // codegen_->GenerateReadBarrierSlow(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.
@@ -621,7 +671,9 @@
DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(out_.reg()));
DCHECK(!instruction_->IsInvoke() ||
(instruction_->IsInvokeStaticOrDirect() &&
- instruction_->GetLocations()->Intrinsified()));
+ instruction_->GetLocations()->Intrinsified()))
+ << "Unexpected instruction in read barrier for heap reference slow path: "
+ << instruction_->DebugName();
// The read barrier instrumentation does not support the
// HArm64IntermediateAddress instruction yet.
DCHECK(!(instruction_->IsArrayGet() &&
@@ -769,14 +821,18 @@
class ReadBarrierForRootSlowPathARM64 : public SlowPathCodeARM64 {
public:
ReadBarrierForRootSlowPathARM64(HInstruction* instruction, Location out, Location root)
- : instruction_(instruction), out_(out), root_(root) {}
+ : instruction_(instruction), out_(out), root_(root) {
+ DCHECK(kEmitCompilerReadBarrier);
+ }
void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
LocationSummary* locations = instruction_->GetLocations();
Primitive::Type type = Primitive::kPrimNot;
DCHECK(locations->CanCall());
DCHECK(!locations->GetLiveRegisters()->ContainsCoreRegister(out_.reg()));
- DCHECK(instruction_->IsLoadClass() || instruction_->IsLoadString());
+ DCHECK(instruction_->IsLoadClass() || instruction_->IsLoadString())
+ << "Unexpected instruction in read barrier for GC root slow path: "
+ << instruction_->DebugName();
__ Bind(GetEntryLabel());
SaveLiveRegisters(codegen, locations);
@@ -1338,7 +1394,8 @@
void CodeGeneratorARM64::LoadAcquire(HInstruction* instruction,
CPURegister dst,
- const MemOperand& src) {
+ const MemOperand& src,
+ bool needs_null_check) {
MacroAssembler* masm = GetVIXLAssembler();
BlockPoolsScope block_pools(masm);
UseScratchRegisterScope temps(masm);
@@ -1354,20 +1411,28 @@
switch (type) {
case Primitive::kPrimBoolean:
__ Ldarb(Register(dst), base);
- MaybeRecordImplicitNullCheck(instruction);
+ if (needs_null_check) {
+ MaybeRecordImplicitNullCheck(instruction);
+ }
break;
case Primitive::kPrimByte:
__ Ldarb(Register(dst), base);
- MaybeRecordImplicitNullCheck(instruction);
+ if (needs_null_check) {
+ MaybeRecordImplicitNullCheck(instruction);
+ }
__ Sbfx(Register(dst), Register(dst), 0, Primitive::ComponentSize(type) * kBitsPerByte);
break;
case Primitive::kPrimChar:
__ Ldarh(Register(dst), base);
- MaybeRecordImplicitNullCheck(instruction);
+ if (needs_null_check) {
+ MaybeRecordImplicitNullCheck(instruction);
+ }
break;
case Primitive::kPrimShort:
__ Ldarh(Register(dst), base);
- MaybeRecordImplicitNullCheck(instruction);
+ if (needs_null_check) {
+ MaybeRecordImplicitNullCheck(instruction);
+ }
__ Sbfx(Register(dst), Register(dst), 0, Primitive::ComponentSize(type) * kBitsPerByte);
break;
case Primitive::kPrimInt:
@@ -1375,7 +1440,9 @@
case Primitive::kPrimLong:
DCHECK_EQ(dst.Is64Bits(), Primitive::Is64BitType(type));
__ Ldar(Register(dst), base);
- MaybeRecordImplicitNullCheck(instruction);
+ if (needs_null_check) {
+ MaybeRecordImplicitNullCheck(instruction);
+ }
break;
case Primitive::kPrimFloat:
case Primitive::kPrimDouble: {
@@ -1384,7 +1451,9 @@
Register temp = dst.Is64Bits() ? temps.AcquireX() : temps.AcquireW();
__ Ldar(temp, base);
- MaybeRecordImplicitNullCheck(instruction);
+ if (needs_null_check) {
+ MaybeRecordImplicitNullCheck(instruction);
+ }
__ Fmov(FPRegister(dst), temp);
break;
}
@@ -1505,7 +1574,7 @@
__ Bind(slow_path->GetExitLabel());
}
-void InstructionCodeGeneratorARM64::GenerateMemoryBarrier(MemBarrierKind kind) {
+void CodeGeneratorARM64::GenerateMemoryBarrier(MemBarrierKind kind) {
BarrierType type = BarrierAll;
switch (kind) {
@@ -1641,33 +1710,62 @@
void InstructionCodeGeneratorARM64::HandleFieldGet(HInstruction* instruction,
const FieldInfo& field_info) {
DCHECK(instruction->IsInstanceFieldGet() || instruction->IsStaticFieldGet());
+ LocationSummary* locations = instruction->GetLocations();
+ Location base_loc = locations->InAt(0);
+ Location out = locations->Out();
+ uint32_t offset = field_info.GetFieldOffset().Uint32Value();
Primitive::Type field_type = field_info.GetFieldType();
BlockPoolsScope block_pools(GetVIXLAssembler());
MemOperand field = HeapOperand(InputRegisterAt(instruction, 0), field_info.GetFieldOffset());
bool use_acquire_release = codegen_->GetInstructionSetFeatures().PreferAcquireRelease();
- if (field_info.IsVolatile()) {
- if (use_acquire_release) {
- // NB: LoadAcquire will record the pc info if needed.
- codegen_->LoadAcquire(instruction, OutputCPURegister(instruction), field);
+ if (field_type == Primitive::kPrimNot && kEmitCompilerReadBarrier && kUseBakerReadBarrier) {
+ // Object FieldGet with Baker's read barrier case.
+ MacroAssembler* masm = GetVIXLAssembler();
+ UseScratchRegisterScope temps(masm);
+ // /* HeapReference<Object> */ out = *(base + offset)
+ Register base = RegisterFrom(base_loc, Primitive::kPrimNot);
+ Register temp = temps.AcquireW();
+ // Note that potential implicit null checks are handled in this
+ // CodeGeneratorARM64::GenerateFieldLoadWithBakerReadBarrier call.
+ codegen_->GenerateFieldLoadWithBakerReadBarrier(
+ instruction,
+ out,
+ base,
+ offset,
+ temp,
+ /* needs_null_check */ true,
+ field_info.IsVolatile() && use_acquire_release);
+ if (field_info.IsVolatile() && !use_acquire_release) {
+ // For IRIW sequential consistency kLoadAny is not sufficient.
+ codegen_->GenerateMemoryBarrier(MemBarrierKind::kAnyAny);
+ }
+ } else {
+ // General case.
+ if (field_info.IsVolatile()) {
+ if (use_acquire_release) {
+ // Note that a potential implicit null check is handled in this
+ // CodeGeneratorARM64::LoadAcquire call.
+ // NB: LoadAcquire will record the pc info if needed.
+ codegen_->LoadAcquire(
+ instruction, OutputCPURegister(instruction), field, /* needs_null_check */ true);
+ } else {
+ codegen_->Load(field_type, OutputCPURegister(instruction), field);
+ codegen_->MaybeRecordImplicitNullCheck(instruction);
+ // For IRIW sequential consistency kLoadAny is not sufficient.
+ codegen_->GenerateMemoryBarrier(MemBarrierKind::kAnyAny);
+ }
} else {
codegen_->Load(field_type, OutputCPURegister(instruction), field);
codegen_->MaybeRecordImplicitNullCheck(instruction);
- // For IRIW sequential consistency kLoadAny is not sufficient.
- GenerateMemoryBarrier(MemBarrierKind::kAnyAny);
}
- } else {
- codegen_->Load(field_type, OutputCPURegister(instruction), field);
- codegen_->MaybeRecordImplicitNullCheck(instruction);
- }
-
- if (field_type == Primitive::kPrimNot) {
- LocationSummary* locations = instruction->GetLocations();
- Location base = locations->InAt(0);
- Location out = locations->Out();
- uint32_t offset = field_info.GetFieldOffset().Uint32Value();
- codegen_->MaybeGenerateReadBarrier(instruction, out, out, base, offset);
+ if (field_type == Primitive::kPrimNot) {
+ // If read barriers are enabled, emit read barriers other than
+ // Baker's using a slow path (and also unpoison the loaded
+ // reference, if heap poisoning is enabled).
+ codegen_->MaybeGenerateReadBarrierSlow(instruction, out, out, base_loc, offset);
+ }
}
}
@@ -1713,10 +1811,10 @@
codegen_->StoreRelease(field_type, source, HeapOperand(obj, offset));
codegen_->MaybeRecordImplicitNullCheck(instruction);
} else {
- GenerateMemoryBarrier(MemBarrierKind::kAnyStore);
+ codegen_->GenerateMemoryBarrier(MemBarrierKind::kAnyStore);
codegen_->Store(field_type, source, HeapOperand(obj, offset));
codegen_->MaybeRecordImplicitNullCheck(instruction);
- GenerateMemoryBarrier(MemBarrierKind::kAnyAny);
+ codegen_->GenerateMemoryBarrier(MemBarrierKind::kAnyAny);
}
} else {
codegen_->Store(field_type, source, HeapOperand(obj, offset));
@@ -2021,50 +2119,62 @@
LocationSummary* locations = instruction->GetLocations();
Location index = locations->InAt(1);
uint32_t offset = mirror::Array::DataOffset(Primitive::ComponentSize(type)).Uint32Value();
- MemOperand source = HeapOperand(obj);
- CPURegister dest = OutputCPURegister(instruction);
+ Location out = locations->Out();
MacroAssembler* masm = GetVIXLAssembler();
UseScratchRegisterScope temps(masm);
// Block pools between `Load` and `MaybeRecordImplicitNullCheck`.
BlockPoolsScope block_pools(masm);
- if (index.IsConstant()) {
- offset += Int64ConstantFrom(index) << Primitive::ComponentSizeShift(type);
- source = HeapOperand(obj, offset);
+ if (type == Primitive::kPrimNot && kEmitCompilerReadBarrier && kUseBakerReadBarrier) {
+ // Object ArrayGet with Baker's read barrier case.
+ Register temp = temps.AcquireW();
+ // The read barrier instrumentation does not support the
+ // HArm64IntermediateAddress instruction yet.
+ DCHECK(!instruction->GetArray()->IsArm64IntermediateAddress());
+ // Note that a potential implicit null check is handled in the
+ // CodeGeneratorARM64::GenerateArrayLoadWithBakerReadBarrier call.
+ codegen_->GenerateArrayLoadWithBakerReadBarrier(
+ instruction, out, obj.W(), offset, index, temp, /* needs_null_check */ true);
} else {
- Register temp = temps.AcquireSameSizeAs(obj);
- if (instruction->GetArray()->IsArm64IntermediateAddress()) {
- // The read barrier instrumentation does not support the
- // HArm64IntermediateAddress instruction yet.
- DCHECK(!kEmitCompilerReadBarrier);
- // We do not need to compute the intermediate address from the array: the
- // input instruction has done it already. See the comment in
- // `InstructionSimplifierArm64::TryExtractArrayAccessAddress()`.
- if (kIsDebugBuild) {
- HArm64IntermediateAddress* tmp = instruction->GetArray()->AsArm64IntermediateAddress();
- DCHECK(tmp->GetOffset()->AsIntConstant()->GetValueAsUint64() == offset);
- }
- temp = obj;
- } else {
- __ Add(temp, obj, offset);
- }
- source = HeapOperand(temp, XRegisterFrom(index), LSL, Primitive::ComponentSizeShift(type));
- }
-
- codegen_->Load(type, dest, source);
- codegen_->MaybeRecordImplicitNullCheck(instruction);
-
- if (type == Primitive::kPrimNot) {
- static_assert(
- sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
- "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
- Location obj_loc = locations->InAt(0);
- Location out = locations->Out();
+ // General case.
+ MemOperand source = HeapOperand(obj);
if (index.IsConstant()) {
- codegen_->MaybeGenerateReadBarrier(instruction, out, out, obj_loc, offset);
+ offset += Int64ConstantFrom(index) << Primitive::ComponentSizeShift(type);
+ source = HeapOperand(obj, offset);
} else {
- codegen_->MaybeGenerateReadBarrier(instruction, out, out, obj_loc, offset, index);
+ Register temp = temps.AcquireSameSizeAs(obj);
+ if (instruction->GetArray()->IsArm64IntermediateAddress()) {
+ // The read barrier instrumentation does not support the
+ // HArm64IntermediateAddress instruction yet.
+ DCHECK(!kEmitCompilerReadBarrier);
+ // We do not need to compute the intermediate address from the array: the
+ // input instruction has done it already. See the comment in
+ // `InstructionSimplifierArm64::TryExtractArrayAccessAddress()`.
+ if (kIsDebugBuild) {
+ HArm64IntermediateAddress* tmp = instruction->GetArray()->AsArm64IntermediateAddress();
+ DCHECK_EQ(tmp->GetOffset()->AsIntConstant()->GetValueAsUint64(), offset);
+ }
+ temp = obj;
+ } else {
+ __ Add(temp, obj, offset);
+ }
+ source = HeapOperand(temp, XRegisterFrom(index), LSL, Primitive::ComponentSizeShift(type));
+ }
+
+ codegen_->Load(type, OutputCPURegister(instruction), source);
+ codegen_->MaybeRecordImplicitNullCheck(instruction);
+
+ if (type == Primitive::kPrimNot) {
+ static_assert(
+ sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
+ "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
+ Location obj_loc = locations->InAt(0);
+ if (index.IsConstant()) {
+ codegen_->MaybeGenerateReadBarrierSlow(instruction, out, out, obj_loc, offset);
+ } else {
+ codegen_->MaybeGenerateReadBarrierSlow(instruction, out, out, obj_loc, offset, index);
+ }
}
}
}
@@ -2194,12 +2304,12 @@
// __ Mov(temp2, temp);
// // /* HeapReference<Class> */ temp = temp->component_type_
// __ Ldr(temp, HeapOperand(temp, component_offset));
- // codegen_->GenerateReadBarrier(
+ // codegen_->GenerateReadBarrierSlow(
// instruction, temp_loc, temp_loc, temp2_loc, component_offset);
//
// // /* HeapReference<Class> */ temp2 = value->klass_
// __ Ldr(temp2, HeapOperand(Register(value), class_offset));
- // codegen_->GenerateReadBarrier(
+ // codegen_->GenerateReadBarrierSlow(
// instruction, temp2_loc, temp2_loc, value_loc, class_offset, temp_loc);
//
// __ Cmp(temp, temp2);
@@ -2921,6 +3031,14 @@
HandleFieldSet(instruction, instruction->GetFieldInfo(), instruction->GetValueCanBeNull());
}
+static bool TypeCheckNeedsATemporary(TypeCheckKind type_check_kind) {
+ return kEmitCompilerReadBarrier &&
+ (kUseBakerReadBarrier ||
+ type_check_kind == TypeCheckKind::kAbstractClassCheck ||
+ type_check_kind == TypeCheckKind::kClassHierarchyCheck ||
+ type_check_kind == TypeCheckKind::kArrayObjectCheck);
+}
+
void LocationsBuilderARM64::VisitInstanceOf(HInstanceOf* instruction) {
LocationSummary::CallKind call_kind = LocationSummary::kNoCall;
TypeCheckKind type_check_kind = instruction->GetTypeCheckKind();
@@ -2947,21 +3065,22 @@
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)) {
+ if (TypeCheckNeedsATemporary(type_check_kind)) {
locations->AddTemp(Location::RequiresRegister());
}
}
void InstructionCodeGeneratorARM64::VisitInstanceOf(HInstanceOf* instruction) {
+ TypeCheckKind type_check_kind = instruction->GetTypeCheckKind();
LocationSummary* locations = instruction->GetLocations();
Location obj_loc = locations->InAt(0);
Register obj = InputRegisterAt(instruction, 0);
Register cls = InputRegisterAt(instruction, 1);
Location out_loc = locations->Out();
Register out = OutputRegister(instruction);
+ Location maybe_temp_loc = TypeCheckNeedsATemporary(type_check_kind) ?
+ locations->GetTemp(0) :
+ Location::NoLocation();
uint32_t class_offset = mirror::Object::ClassOffset().Int32Value();
uint32_t super_offset = mirror::Class::SuperClassOffset().Int32Value();
uint32_t component_offset = mirror::Class::ComponentTypeOffset().Int32Value();
@@ -2977,10 +3096,9 @@
}
// /* HeapReference<Class> */ out = obj->klass_
- __ Ldr(out, HeapOperand(obj.W(), class_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, out_loc, out_loc, obj_loc, class_offset);
+ GenerateReferenceLoadTwoRegisters(instruction, out_loc, obj_loc, class_offset, maybe_temp_loc);
- switch (instruction->GetTypeCheckKind()) {
+ switch (type_check_kind) {
case TypeCheckKind::kExactCheck: {
__ Cmp(out, cls);
__ Cset(out, eq);
@@ -2995,17 +3113,8 @@
// object to avoid doing a comparison we know will fail.
vixl::Label loop, success;
__ 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 = WRegisterFrom(temp_loc);
- __ Mov(temp, out);
- }
// /* HeapReference<Class> */ out = out->super_class_
- __ Ldr(out, HeapOperand(out, super_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, out_loc, out_loc, temp_loc, super_offset);
+ GenerateReferenceLoadOneRegister(instruction, out_loc, super_offset, maybe_temp_loc);
// If `out` is null, we use it for the result, and jump to `done`.
__ Cbz(out, &done);
__ Cmp(out, cls);
@@ -3023,17 +3132,8 @@
__ Bind(&loop);
__ Cmp(out, cls);
__ B(eq, &success);
- 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 = WRegisterFrom(temp_loc);
- __ Mov(temp, out);
- }
// /* HeapReference<Class> */ out = out->super_class_
- __ Ldr(out, HeapOperand(out, super_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, out_loc, out_loc, temp_loc, super_offset);
+ GenerateReferenceLoadOneRegister(instruction, out_loc, super_offset, maybe_temp_loc);
__ Cbnz(out, &loop);
// If `out` is null, we use it for the result, and jump to `done`.
__ B(&done);
@@ -3051,17 +3151,8 @@
__ Cmp(out, cls);
__ B(eq, &exact_check);
// 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 = WRegisterFrom(temp_loc);
- __ Mov(temp, out);
- }
// /* HeapReference<Class> */ out = out->component_type_
- __ Ldr(out, HeapOperand(out, component_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, out_loc, out_loc, temp_loc, component_offset);
+ GenerateReferenceLoadOneRegister(instruction, out_loc, component_offset, maybe_temp_loc);
// If `out` is null, we use it for the result, and jump to `done`.
__ Cbz(out, &done);
__ Ldrh(out, HeapOperand(out, primitive_offset));
@@ -3100,6 +3191,13 @@
// HInstanceOf instruction (following the runtime calling
// convention), which might be cluttered by the potential first
// read barrier emission at the beginning of this method.
+ //
+ // TODO: Introduce a new runtime entry point taking the object
+ // to test (instead of its class) as argument, and let it deal
+ // with the read barrier issues. This will let us refactor this
+ // case of the `switch` code as it was previously (with a direct
+ // call to the runtime not using a type checking slow path).
+ // This should also be beneficial for the other cases above.
DCHECK(locations->OnlyCallsOnSlowPath());
slow_path = new (GetGraph()->GetArena()) TypeCheckSlowPathARM64(instruction,
/* is_fatal */ false);
@@ -3152,30 +3250,29 @@
locations->SetInAt(1, Location::RequiresRegister());
// Note that TypeCheckSlowPathARM64 uses this "temp" register too.
locations->AddTemp(Location::RequiresRegister());
- 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());
+ if (TypeCheckNeedsATemporary(type_check_kind)) {
+ locations->AddTemp(Location::RequiresRegister());
}
}
void InstructionCodeGeneratorARM64::VisitCheckCast(HCheckCast* instruction) {
+ TypeCheckKind type_check_kind = instruction->GetTypeCheckKind();
LocationSummary* locations = instruction->GetLocations();
Location obj_loc = locations->InAt(0);
Register obj = InputRegisterAt(instruction, 0);
Register cls = InputRegisterAt(instruction, 1);
Location temp_loc = locations->GetTemp(0);
+ Location maybe_temp2_loc = TypeCheckNeedsATemporary(type_check_kind) ?
+ locations->GetTemp(1) :
+ Location::NoLocation();
Register temp = WRegisterFrom(temp_loc);
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();
- TypeCheckKind type_check_kind = instruction->GetTypeCheckKind();
bool is_type_check_slow_path_fatal =
(type_check_kind == TypeCheckKind::kExactCheck ||
type_check_kind == TypeCheckKind::kAbstractClassCheck ||
@@ -3194,8 +3291,7 @@
}
// /* HeapReference<Class> */ temp = obj->klass_
- __ Ldr(temp, HeapOperand(obj, class_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ GenerateReferenceLoadTwoRegisters(instruction, temp_loc, obj_loc, class_offset, maybe_temp2_loc);
switch (type_check_kind) {
case TypeCheckKind::kExactCheck:
@@ -3212,18 +3308,8 @@
// object to avoid doing a comparison we know will fail.
vixl::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 = WRegisterFrom(temp2_loc);
- __ Mov(temp2, temp);
- }
// /* HeapReference<Class> */ temp = temp->super_class_
- __ Ldr(temp, HeapOperand(temp, super_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, temp2_loc, super_offset);
+ GenerateReferenceLoadOneRegister(instruction, temp_loc, super_offset, maybe_temp2_loc);
// If the class reference currently in `temp` is not null, jump
// to the `compare_classes` label to compare it with the checked
@@ -3235,8 +3321,8 @@
// going into the slow path, as it has been overwritten in the
// meantime.
// /* HeapReference<Class> */ temp = obj->klass_
- __ Ldr(temp, HeapOperand(obj, class_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ GenerateReferenceLoadTwoRegisters(
+ instruction, temp_loc, obj_loc, class_offset, maybe_temp2_loc);
__ B(type_check_slow_path->GetEntryLabel());
__ Bind(&compare_classes);
@@ -3252,18 +3338,8 @@
__ Cmp(temp, cls);
__ B(eq, &done);
- 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 = WRegisterFrom(temp2_loc);
- __ Mov(temp2, temp);
- }
// /* HeapReference<Class> */ temp = temp->super_class_
- __ Ldr(temp, HeapOperand(temp, super_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, temp2_loc, super_offset);
+ GenerateReferenceLoadOneRegister(instruction, temp_loc, super_offset, maybe_temp2_loc);
// If the class reference currently in `temp` is not null, jump
// back at the beginning of the loop.
@@ -3274,8 +3350,8 @@
// going into the slow path, as it has been overwritten in the
// meantime.
// /* HeapReference<Class> */ temp = obj->klass_
- __ Ldr(temp, HeapOperand(obj, class_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ GenerateReferenceLoadTwoRegisters(
+ instruction, temp_loc, obj_loc, class_offset, maybe_temp2_loc);
__ B(type_check_slow_path->GetEntryLabel());
break;
}
@@ -3287,19 +3363,8 @@
__ B(eq, &done);
// 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 = WRegisterFrom(temp2_loc);
- __ Mov(temp2, temp);
- }
// /* HeapReference<Class> */ temp = temp->component_type_
- __ Ldr(temp, HeapOperand(temp, component_offset));
- codegen_->MaybeGenerateReadBarrier(
- instruction, temp_loc, temp_loc, temp2_loc, component_offset);
+ GenerateReferenceLoadOneRegister(instruction, temp_loc, component_offset, maybe_temp2_loc);
// If the component type is not null (i.e. the object is indeed
// an array), jump to label `check_non_primitive_component_type`
@@ -3312,8 +3377,8 @@
// going into the slow path, as it has been overwritten in the
// meantime.
// /* HeapReference<Class> */ temp = obj->klass_
- __ Ldr(temp, HeapOperand(obj, class_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ GenerateReferenceLoadTwoRegisters(
+ instruction, temp_loc, obj_loc, class_offset, maybe_temp2_loc);
__ B(type_check_slow_path->GetEntryLabel());
__ Bind(&check_non_primitive_component_type);
@@ -3322,8 +3387,8 @@
__ Cbz(temp, &done);
// Same comment as above regarding `temp` and the slow path.
// /* HeapReference<Class> */ temp = obj->klass_
- __ Ldr(temp, HeapOperand(obj, class_offset));
- codegen_->MaybeGenerateReadBarrier(instruction, temp_loc, temp_loc, obj_loc, class_offset);
+ GenerateReferenceLoadTwoRegisters(
+ instruction, temp_loc, obj_loc, class_offset, maybe_temp2_loc);
__ B(type_check_slow_path->GetEntryLabel());
break;
}
@@ -3340,6 +3405,13 @@
// instruction (following the runtime calling convention), which
// might be cluttered by the potential first read barrier
// emission at the beginning of this method.
+ //
+ // TODO: Introduce a new runtime entry point taking the object
+ // to test (instead of its class) as argument, and let it deal
+ // with the read barrier issues. This will let us refactor this
+ // case of the `switch` code as it was previously (with a direct
+ // call to the runtime not using a type checking slow path).
+ // This should also be beneficial for the other cases above.
__ B(type_check_slow_path->GetEntryLabel());
break;
}
@@ -3465,7 +3537,7 @@
HInvokeStaticOrDirect::DispatchInfo CodeGeneratorARM64::GetSupportedInvokeStaticOrDirectDispatch(
const HInvokeStaticOrDirect::DispatchInfo& desired_dispatch_info,
MethodReference target_method ATTRIBUTE_UNUSED) {
- // On arm64 we support all dispatch types.
+ // On ARM64 we support all dispatch types.
return desired_dispatch_info;
}
@@ -3742,32 +3814,17 @@
if (cls->IsReferrersClass()) {
DCHECK(!cls->CanCallRuntime());
DCHECK(!cls->MustGenerateClinitCheck());
- uint32_t declaring_class_offset = ArtMethod::DeclaringClassOffset().Int32Value();
- if (kEmitCompilerReadBarrier) {
- // /* GcRoot<mirror::Class>* */ out = &(current_method->declaring_class_)
- __ Add(out.X(), current_method.X(), declaring_class_offset);
- // /* mirror::Class* */ out = out->Read()
- codegen_->GenerateReadBarrierForRoot(cls, out_loc, out_loc);
- } else {
- // /* GcRoot<mirror::Class> */ out = current_method->declaring_class_
- __ Ldr(out, MemOperand(current_method, declaring_class_offset));
- }
+ // /* GcRoot<mirror::Class> */ out = current_method->declaring_class_
+ GenerateGcRootFieldLoad(
+ cls, out_loc, current_method, ArtMethod::DeclaringClassOffset().Int32Value());
} else {
MemberOffset resolved_types_offset = ArtMethod::DexCacheResolvedTypesOffset(kArm64PointerSize);
// /* GcRoot<mirror::Class>[] */ out =
// current_method.ptr_sized_fields_->dex_cache_resolved_types_
__ Ldr(out.X(), MemOperand(current_method, resolved_types_offset.Int32Value()));
-
- size_t cache_offset = CodeGenerator::GetCacheOffset(cls->GetTypeIndex());
- if (kEmitCompilerReadBarrier) {
- // /* GcRoot<mirror::Class>* */ out = &out[type_index]
- __ Add(out.X(), out.X(), cache_offset);
- // /* mirror::Class* */ out = out->Read()
- codegen_->GenerateReadBarrierForRoot(cls, out_loc, out_loc);
- } else {
- // /* GcRoot<mirror::Class> */ out = out[type_index]
- __ Ldr(out, MemOperand(out.X(), cache_offset));
- }
+ // /* GcRoot<mirror::Class> */ out = out[type_index]
+ GenerateGcRootFieldLoad(
+ cls, out_loc, out.X(), CodeGenerator::GetCacheOffset(cls->GetTypeIndex()));
if (!cls->IsInDexCache() || cls->MustGenerateClinitCheck()) {
DCHECK(cls->CanCallRuntime());
@@ -3830,30 +3887,14 @@
Register out = OutputRegister(load);
Register current_method = InputRegisterAt(load, 0);
- uint32_t declaring_class_offset = ArtMethod::DeclaringClassOffset().Int32Value();
- if (kEmitCompilerReadBarrier) {
- // /* GcRoot<mirror::Class>* */ out = &(current_method->declaring_class_)
- __ Add(out.X(), current_method.X(), declaring_class_offset);
- // /* mirror::Class* */ out = out->Read()
- codegen_->GenerateReadBarrierForRoot(load, out_loc, out_loc);
- } else {
- // /* GcRoot<mirror::Class> */ out = current_method->declaring_class_
- __ Ldr(out, MemOperand(current_method, declaring_class_offset));
- }
-
+ // /* GcRoot<mirror::Class> */ out = current_method->declaring_class_
+ GenerateGcRootFieldLoad(
+ load, out_loc, current_method, ArtMethod::DeclaringClassOffset().Int32Value());
// /* GcRoot<mirror::String>[] */ out = out->dex_cache_strings_
__ Ldr(out.X(), HeapOperand(out, mirror::Class::DexCacheStringsOffset().Uint32Value()));
-
- size_t cache_offset = CodeGenerator::GetCacheOffset(load->GetStringIndex());
- if (kEmitCompilerReadBarrier) {
- // /* GcRoot<mirror::String>* */ out = &out[string_index]
- __ Add(out.X(), out.X(), cache_offset);
- // /* mirror::String* */ out = out->Read()
- codegen_->GenerateReadBarrierForRoot(load, out_loc, out_loc);
- } else {
- // /* GcRoot<mirror::String> */ out = out[string_index]
- __ Ldr(out, MemOperand(out.X(), cache_offset));
- }
+ // /* GcRoot<mirror::String> */ out = out[string_index]
+ GenerateGcRootFieldLoad(
+ load, out_loc, out.X(), CodeGenerator::GetCacheOffset(load->GetStringIndex()));
if (!load->IsInDexCache()) {
SlowPathCodeARM64* slow_path = new (GetGraph()->GetArena()) LoadStringSlowPathARM64(load);
@@ -4222,7 +4263,7 @@
}
void InstructionCodeGeneratorARM64::VisitMemoryBarrier(HMemoryBarrier* memory_barrier) {
- GenerateMemoryBarrier(memory_barrier->GetBarrierKind());
+ codegen_->GenerateMemoryBarrier(memory_barrier->GetBarrierKind());
}
void LocationsBuilderARM64::VisitReturn(HReturn* instruction) {
@@ -4607,14 +4648,288 @@
}
}
-void CodeGeneratorARM64::GenerateReadBarrier(HInstruction* instruction,
- Location out,
- Location ref,
- Location obj,
- uint32_t offset,
- Location index) {
+void InstructionCodeGeneratorARM64::GenerateReferenceLoadOneRegister(HInstruction* instruction,
+ Location out,
+ uint32_t offset,
+ Location maybe_temp) {
+ Primitive::Type type = Primitive::kPrimNot;
+ Register out_reg = RegisterFrom(out, type);
+ if (kEmitCompilerReadBarrier) {
+ Register temp_reg = RegisterFrom(maybe_temp, type);
+ if (kUseBakerReadBarrier) {
+ // Load with fast path based Baker's read barrier.
+ // /* HeapReference<Object> */ out = *(out + offset)
+ codegen_->GenerateFieldLoadWithBakerReadBarrier(instruction,
+ out,
+ out_reg,
+ offset,
+ temp_reg,
+ /* needs_null_check */ false,
+ /* use_load_acquire */ false);
+ } else {
+ // Load with slow path based read barrier.
+ // Save the value of `out` into `maybe_temp` before overwriting it
+ // in the following move operation, as we will need it for the
+ // read barrier below.
+ __ Mov(temp_reg, out_reg);
+ // /* HeapReference<Object> */ out = *(out + offset)
+ __ Ldr(out_reg, HeapOperand(out_reg, offset));
+ codegen_->GenerateReadBarrierSlow(instruction, out, out, maybe_temp, offset);
+ }
+ } else {
+ // Plain load with no read barrier.
+ // /* HeapReference<Object> */ out = *(out + offset)
+ __ Ldr(out_reg, HeapOperand(out_reg, offset));
+ GetAssembler()->MaybeUnpoisonHeapReference(out_reg);
+ }
+}
+
+void InstructionCodeGeneratorARM64::GenerateReferenceLoadTwoRegisters(HInstruction* instruction,
+ Location out,
+ Location obj,
+ uint32_t offset,
+ Location maybe_temp) {
+ Primitive::Type type = Primitive::kPrimNot;
+ Register out_reg = RegisterFrom(out, type);
+ Register obj_reg = RegisterFrom(obj, type);
+ if (kEmitCompilerReadBarrier) {
+ if (kUseBakerReadBarrier) {
+ // Load with fast path based Baker's read barrier.
+ Register temp_reg = RegisterFrom(maybe_temp, type);
+ // /* HeapReference<Object> */ out = *(obj + offset)
+ codegen_->GenerateFieldLoadWithBakerReadBarrier(instruction,
+ out,
+ obj_reg,
+ offset,
+ temp_reg,
+ /* needs_null_check */ false,
+ /* use_load_acquire */ false);
+ } else {
+ // Load with slow path based read barrier.
+ // /* HeapReference<Object> */ out = *(obj + offset)
+ __ Ldr(out_reg, HeapOperand(obj_reg, offset));
+ codegen_->GenerateReadBarrierSlow(instruction, out, out, obj, offset);
+ }
+ } else {
+ // Plain load with no read barrier.
+ // /* HeapReference<Object> */ out = *(obj + offset)
+ __ Ldr(out_reg, HeapOperand(obj_reg, offset));
+ GetAssembler()->MaybeUnpoisonHeapReference(out_reg);
+ }
+}
+
+void InstructionCodeGeneratorARM64::GenerateGcRootFieldLoad(HInstruction* instruction,
+ Location root,
+ vixl::Register obj,
+ uint32_t offset) {
+ Register root_reg = RegisterFrom(root, Primitive::kPrimNot);
+ if (kEmitCompilerReadBarrier) {
+ if (kUseBakerReadBarrier) {
+ // Fast path implementation of art::ReadBarrier::BarrierForRoot when
+ // Baker's read barrier are used:
+ //
+ // root = obj.field;
+ // if (Thread::Current()->GetIsGcMarking()) {
+ // root = ReadBarrier::Mark(root)
+ // }
+
+ // /* GcRoot<mirror::Object> */ root = *(obj + offset)
+ __ Ldr(root_reg, MemOperand(obj, offset));
+ static_assert(
+ sizeof(mirror::CompressedReference<mirror::Object>) == sizeof(GcRoot<mirror::Object>),
+ "art::mirror::CompressedReference<mirror::Object> and art::GcRoot<mirror::Object> "
+ "have different sizes.");
+ static_assert(sizeof(mirror::CompressedReference<mirror::Object>) == sizeof(int32_t),
+ "art::mirror::CompressedReference<mirror::Object> and int32_t "
+ "have different sizes.");
+
+ // Slow path used to mark the GC root `root`.
+ SlowPathCodeARM64* slow_path =
+ new (GetGraph()->GetArena()) ReadBarrierMarkSlowPathARM64(instruction, root, root);
+ codegen_->AddSlowPath(slow_path);
+
+ MacroAssembler* masm = GetVIXLAssembler();
+ UseScratchRegisterScope temps(masm);
+ Register temp = temps.AcquireW();
+ // temp = Thread::Current()->GetIsGcMarking()
+ __ Ldr(temp, MemOperand(tr, Thread::IsGcMarkingOffset<kArm64WordSize>().Int32Value()));
+ __ Cbnz(temp, slow_path->GetEntryLabel());
+ __ Bind(slow_path->GetExitLabel());
+ } else {
+ // GC root loaded through a slow path for read barriers other
+ // than Baker's.
+ // /* GcRoot<mirror::Object>* */ root = obj + offset
+ __ Add(root_reg.X(), obj.X(), offset);
+ // /* mirror::Object* */ root = root->Read()
+ codegen_->GenerateReadBarrierForRootSlow(instruction, root, root);
+ }
+ } else {
+ // Plain GC root load with no read barrier.
+ // /* GcRoot<mirror::Object> */ root = *(obj + offset)
+ __ Ldr(root_reg, MemOperand(obj, offset));
+ // Note that GC roots are not affected by heap poisoning, thus we
+ // do not have to unpoison `root_reg` here.
+ }
+}
+
+void CodeGeneratorARM64::GenerateFieldLoadWithBakerReadBarrier(HInstruction* instruction,
+ Location ref,
+ vixl::Register obj,
+ uint32_t offset,
+ Register temp,
+ bool needs_null_check,
+ bool use_load_acquire) {
+ DCHECK(kEmitCompilerReadBarrier);
+ DCHECK(kUseBakerReadBarrier);
+
+ // /* HeapReference<Object> */ ref = *(obj + offset)
+ Location no_index = Location::NoLocation();
+ GenerateReferenceLoadWithBakerReadBarrier(
+ instruction, ref, obj, offset, no_index, temp, needs_null_check, use_load_acquire);
+}
+
+void CodeGeneratorARM64::GenerateArrayLoadWithBakerReadBarrier(HInstruction* instruction,
+ Location ref,
+ vixl::Register obj,
+ uint32_t data_offset,
+ Location index,
+ Register temp,
+ bool needs_null_check) {
+ DCHECK(kEmitCompilerReadBarrier);
+ DCHECK(kUseBakerReadBarrier);
+
+ // Array cells are never volatile variables, therefore array loads
+ // never use Load-Acquire instructions on ARM64.
+ const bool use_load_acquire = false;
+
+ // /* HeapReference<Object> */ ref =
+ // *(obj + data_offset + index * sizeof(HeapReference<Object>))
+ GenerateReferenceLoadWithBakerReadBarrier(
+ instruction, ref, obj, data_offset, index, temp, needs_null_check, use_load_acquire);
+}
+
+void CodeGeneratorARM64::GenerateReferenceLoadWithBakerReadBarrier(HInstruction* instruction,
+ Location ref,
+ vixl::Register obj,
+ uint32_t offset,
+ Location index,
+ Register temp,
+ bool needs_null_check,
+ bool use_load_acquire) {
+ DCHECK(kEmitCompilerReadBarrier);
+ DCHECK(kUseBakerReadBarrier);
+ // If `index` is a valid location, then we are emitting an array
+ // load, so we shouldn't be using a Load Acquire instruction.
+ // In other words: `index.IsValid()` => `!use_load_acquire`.
+ DCHECK(!index.IsValid() || !use_load_acquire);
+
+ MacroAssembler* masm = GetVIXLAssembler();
+ UseScratchRegisterScope temps(masm);
+
+ // In slow path based read barriers, the read barrier call is
+ // inserted after the original load. However, in fast path based
+ // Baker's read barriers, we need to perform the load of
+ // mirror::Object::monitor_ *before* the original reference load.
+ // This load-load ordering is required by the read barrier.
+ // The fast path/slow path (for Baker's algorithm) should look like:
+ //
+ // uint32_t rb_state = Lockword(obj->monitor_).ReadBarrierState();
+ // lfence; // Load fence or artificial data dependency to prevent load-load reordering
+ // HeapReference<Object> ref = *src; // Original reference load.
+ // bool is_gray = (rb_state == ReadBarrier::gray_ptr_);
+ // if (is_gray) {
+ // ref = ReadBarrier::Mark(ref); // Performed by runtime entrypoint slow path.
+ // }
+ //
+ // Note: the original implementation in ReadBarrier::Barrier is
+ // slightly more complex as it performs additional checks that we do
+ // not do here for performance reasons.
+
+ Primitive::Type type = Primitive::kPrimNot;
+ Register ref_reg = RegisterFrom(ref, type);
+ DCHECK(obj.IsW());
+ uint32_t monitor_offset = mirror::Object::MonitorOffset().Int32Value();
+
+ // /* int32_t */ monitor = obj->monitor_
+ __ Ldr(temp, HeapOperand(obj, monitor_offset));
+ if (needs_null_check) {
+ MaybeRecordImplicitNullCheck(instruction);
+ }
+ // /* LockWord */ lock_word = LockWord(monitor)
+ static_assert(sizeof(LockWord) == sizeof(int32_t),
+ "art::LockWord and int32_t have different sizes.");
+ // /* uint32_t */ rb_state = lock_word.ReadBarrierState()
+ __ Lsr(temp, temp, LockWord::kReadBarrierStateShift);
+ __ And(temp, temp, Operand(LockWord::kReadBarrierStateMask));
+ static_assert(
+ LockWord::kReadBarrierStateMask == ReadBarrier::rb_ptr_mask_,
+ "art::LockWord::kReadBarrierStateMask is not equal to art::ReadBarrier::rb_ptr_mask_.");
+
+ // Introduce a dependency on the high bits of rb_state, which shall
+ // be all zeroes, to prevent load-load reordering, and without using
+ // a memory barrier (which would be more expensive).
+ // temp2 = rb_state & ~LockWord::kReadBarrierStateMask = 0
+ Register temp2 = temps.AcquireW();
+ __ Bic(temp2, temp, Operand(LockWord::kReadBarrierStateMask));
+ // obj is unchanged by this operation, but its value now depends on
+ // temp2, which depends on temp.
+ __ Add(obj, obj, Operand(temp2));
+ temps.Release(temp2);
+
+ // The actual reference load.
+ if (index.IsValid()) {
+ static_assert(
+ sizeof(mirror::HeapReference<mirror::Object>) == sizeof(int32_t),
+ "art::mirror::HeapReference<art::mirror::Object> and int32_t have different sizes.");
+ temp2 = temps.AcquireW();
+ // /* HeapReference<Object> */ ref =
+ // *(obj + offset + index * sizeof(HeapReference<Object>))
+ MemOperand source = HeapOperand(obj);
+ if (index.IsConstant()) {
+ uint32_t computed_offset =
+ offset + (Int64ConstantFrom(index) << Primitive::ComponentSizeShift(type));
+ source = HeapOperand(obj, computed_offset);
+ } else {
+ __ Add(temp2, obj, offset);
+ source = HeapOperand(temp2, XRegisterFrom(index), LSL, Primitive::ComponentSizeShift(type));
+ }
+ Load(type, ref_reg, source);
+ temps.Release(temp2);
+ } else {
+ // /* HeapReference<Object> */ ref = *(obj + offset)
+ MemOperand field = HeapOperand(obj, offset);
+ if (use_load_acquire) {
+ LoadAcquire(instruction, ref_reg, field, /* needs_null_check */ false);
+ } else {
+ Load(type, ref_reg, field);
+ }
+ }
+
+ // Object* ref = ref_addr->AsMirrorPtr()
+ GetAssembler()->MaybeUnpoisonHeapReference(ref_reg);
+
+ // Slow path used to mark the object `ref` when it is gray.
+ SlowPathCodeARM64* slow_path =
+ new (GetGraph()->GetArena()) ReadBarrierMarkSlowPathARM64(instruction, ref, ref);
+ AddSlowPath(slow_path);
+
+ // if (rb_state == ReadBarrier::gray_ptr_)
+ // ref = ReadBarrier::Mark(ref);
+ __ Cmp(temp, ReadBarrier::gray_ptr_);
+ __ B(eq, slow_path->GetEntryLabel());
+ __ Bind(slow_path->GetExitLabel());
+}
+
+void CodeGeneratorARM64::GenerateReadBarrierSlow(HInstruction* instruction,
+ Location out,
+ Location ref,
+ Location obj,
+ uint32_t offset,
+ Location index) {
DCHECK(kEmitCompilerReadBarrier);
+ // Insert a slow path based read barrier *after* the reference load.
+ //
// If heap poisoning is enabled, the unpoisoning of the loaded
// reference will be carried out by the runtime within the slow
// path.
@@ -4628,57 +4943,41 @@
ReadBarrierForHeapReferenceSlowPathARM64(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 CodeGeneratorARM64::MaybeGenerateReadBarrier(HInstruction* instruction,
- Location out,
- Location ref,
- Location obj,
- uint32_t offset,
- Location index) {
+void CodeGeneratorARM64::MaybeGenerateReadBarrierSlow(HInstruction* instruction,
+ Location out,
+ Location ref,
+ Location obj,
+ uint32_t offset,
+ Location index) {
if (kEmitCompilerReadBarrier) {
+ // Baker's read barriers shall be handled by the fast path
+ // (CodeGeneratorARM64::GenerateReferenceLoadWithBakerReadBarrier).
+ DCHECK(!kUseBakerReadBarrier);
// 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);
+ GenerateReadBarrierSlow(instruction, out, ref, obj, offset, index);
} else if (kPoisonHeapReferences) {
GetAssembler()->UnpoisonHeapReference(WRegisterFrom(out));
}
}
-void CodeGeneratorARM64::GenerateReadBarrierForRoot(HInstruction* instruction,
- Location out,
- Location root) {
+void CodeGeneratorARM64::GenerateReadBarrierForRootSlow(HInstruction* instruction,
+ Location out,
+ Location root) {
DCHECK(kEmitCompilerReadBarrier);
+ // Insert a slow path based read barrier *after* the GC root load.
+ //
// Note that GC roots are not affected by heap poisoning, so we do
// not need to do anything special for this here.
SlowPathCodeARM64* slow_path =
new (GetGraph()->GetArena()) ReadBarrierForRootSlowPathARM64(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());
}