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dependent-code.cc
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249 lines (219 loc) · 8.41 KB
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// Copyright 2023 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/objects/dependent-code.h"
#include "src/base/bits.h"
#include "src/deoptimizer/deoptimizer.h"
#include "src/objects/allocation-site-inl.h"
#include "src/objects/contexts.h"
#include "src/objects/dependent-code-inl.h"
#include "src/objects/map.h"
namespace v8 {
namespace internal {
Tagged<DependentCode> DependentCode::GetDependentCode(
Tagged<HeapObject> object) {
if (IsMap(object)) {
return Cast<Map>(object)->dependent_code();
} else if (IsPropertyCell(object)) {
return Cast<PropertyCell>(object)->dependent_code();
} else if (IsAllocationSite(object)) {
return Cast<AllocationSite>(object)->dependent_code();
} else if (IsContextCell(object)) {
return Cast<ContextCell>(object)->dependent_code();
} else if (IsScopeInfo(object)) {
return Cast<ScopeInfo>(object)->dependent_code();
}
UNREACHABLE();
}
void DependentCode::SetDependentCode(DirectHandle<HeapObject> object,
DirectHandle<DependentCode> dep) {
if (IsMap(*object)) {
Cast<Map>(object)->set_dependent_code(*dep);
} else if (IsPropertyCell(*object)) {
Cast<PropertyCell>(object)->set_dependent_code(*dep);
} else if (IsAllocationSite(*object)) {
Cast<AllocationSite>(object)->set_dependent_code(*dep);
} else if (IsContextCell(*object)) {
Cast<ContextCell>(object)->set_dependent_code(*dep);
} else if (IsScopeInfo(*object)) {
Cast<ScopeInfo>(object)->set_dependent_code(*dep);
} else {
UNREACHABLE();
}
}
namespace {
void PrintDependencyGroups(DependentCode::DependencyGroups groups) {
while (groups != 0) {
auto group = static_cast<DependentCode::DependencyGroup>(
1 << base::bits::CountTrailingZeros(static_cast<uint32_t>(groups)));
StdoutStream{} << DependentCode::DependencyGroupName(group);
groups &= ~group;
if (groups != 0) StdoutStream{} << ",";
}
}
} // namespace
void DependentCode::InstallDependency(Isolate* isolate, Handle<Code> code,
Handle<HeapObject> object,
DependencyGroups groups) {
if (V8_UNLIKELY(v8_flags.trace_compilation_dependencies)) {
StdoutStream{} << "Installing dependency of [" << code << "] on [" << object
<< "] in groups [";
PrintDependencyGroups(groups);
StdoutStream{} << "]\n";
}
Handle<DependentCode> old_deps(DependentCode::GetDependentCode(*object),
isolate);
DirectHandle<DependentCode> new_deps =
InsertWeakCode(isolate, old_deps, groups, code);
// Update the list head if necessary.
if (!new_deps.is_identical_to(old_deps)) {
DependentCode::SetDependentCode(object, new_deps);
}
}
DirectHandle<DependentCode> DependentCode::InsertWeakCode(
Isolate* isolate, Handle<DependentCode> entries, DependencyGroups groups,
DirectHandle<Code> code) {
if (entries->length() == entries->capacity()) {
// We'd have to grow - try to compact first.
entries->IterateAndCompact(
isolate, [](Tagged<Code>, DependencyGroups) { return false; });
}
// As the Code object lives outside of the sandbox in trusted space, we need
// to use its in-sandbox wrapper object here.
MaybeObjectDirectHandle code_slot(MakeWeak(code->wrapper()), isolate);
entries = Cast<DependentCode>(WeakArrayList::AddToEnd(
isolate, entries, code_slot, Smi::FromInt(groups)));
return entries;
}
template <typename Function>
void DependentCode::IterateAndCompact(IsolateForSandbox isolate,
const Function& fn) {
DisallowGarbageCollection no_gc;
int len = length();
if (len == 0) return;
// We compact during traversal, thus use a somewhat custom loop construct:
//
// - Loop back-to-front s.t. trailing cleared entries can simply drop off
// the back of the list.
// - Any cleared slots are filled from the back of the list.
int i = len - kSlotsPerEntry;
while (i >= 0) {
Tagged<MaybeObject> obj = Get(i + kCodeSlotOffset);
if (obj.IsCleared()) {
len = FillEntryFromBack(i, len);
i -= kSlotsPerEntry;
continue;
}
if (fn(Cast<CodeWrapper>(obj.GetHeapObjectAssumeWeak())->code(isolate),
static_cast<DependencyGroups>(
Get(i + kGroupsSlotOffset).ToSmi().value()))) {
len = FillEntryFromBack(i, len);
}
i -= kSlotsPerEntry;
}
set_length(len);
}
bool DependentCode::MarkCodeForDeoptimization(
Isolate* isolate, DependentCode::DependencyGroups deopt_groups) {
DisallowGarbageCollection no_gc;
bool marked_something = false;
IterateAndCompact(isolate, [&](Tagged<Code> code, DependencyGroups groups) {
if ((groups & deopt_groups) == 0) return false;
if (!code->marked_for_deoptimization()) {
// Pick a single group out of the applicable deopt groups, to use as the
// deopt reason. Only one group is reported to avoid string concatenation.
DependencyGroup first_group = static_cast<DependencyGroup>(
1 << base::bits::CountTrailingZeros32(groups & deopt_groups));
code->SetMarkedForDeoptimization(
isolate,
DependentCode::DependencyGroupToLazyDeoptReason(first_group));
marked_something = true;
}
return true;
});
return marked_something;
}
int DependentCode::FillEntryFromBack(int index, int length) {
DCHECK_EQ(index % 2, 0);
DCHECK_EQ(length % 2, 0);
for (int i = length - kSlotsPerEntry; i > index; i -= kSlotsPerEntry) {
Tagged<MaybeObject> obj = Get(i + kCodeSlotOffset);
if (obj.IsCleared()) continue;
Set(index + kCodeSlotOffset, obj);
Set(index + kGroupsSlotOffset, Get(i + kGroupsSlotOffset),
SKIP_WRITE_BARRIER);
return i;
}
return index; // No non-cleared entry found.
}
void DependentCode::DeoptimizeDependencyGroups(
Isolate* isolate, DependentCode::DependencyGroups groups) {
DisallowGarbageCollection no_gc_scope;
bool marked_something = MarkCodeForDeoptimization(isolate, groups);
if (marked_something) {
DCHECK(AllowCodeDependencyChange::IsAllowed());
Deoptimizer::DeoptimizeMarkedCode(isolate);
}
}
// static
Tagged<DependentCode> DependentCode::empty_dependent_code(
const ReadOnlyRoots& roots) {
return Cast<DependentCode>(roots.empty_weak_array_list());
}
const char* DependentCode::DependencyGroupName(DependencyGroup group) {
switch (group) {
case kTransitionGroup:
return "transition";
case kPrototypeCheckGroup:
return "prototype-check";
case kPropertyCellChangedGroup:
return "property-cell-changed";
case kFieldConstGroup:
return "field-const";
case kFieldTypeGroup:
return "field-type";
case kFieldRepresentationGroup:
return "field-representation";
case kInitialMapChangedGroup:
return "initial-map-changed";
case kAllocationSiteTenuringChangedGroup:
return "allocation-site-tenuring-changed";
case kAllocationSiteTransitionChangedGroup:
return "allocation-site-transition-changed";
case kContextCellChangedGroup:
return "script-context-slot-property-changed";
case kEmptyContextExtensionGroup:
return "empty-context-extension";
}
UNREACHABLE();
}
LazyDeoptimizeReason DependentCode::DependencyGroupToLazyDeoptReason(
DependencyGroup group) {
switch (group) {
case kTransitionGroup:
return LazyDeoptimizeReason::kMapDeprecated;
case kPrototypeCheckGroup:
return LazyDeoptimizeReason::kPrototypeChange;
case kPropertyCellChangedGroup:
return LazyDeoptimizeReason::kPropertyCellChange;
case kFieldConstGroup:
return LazyDeoptimizeReason::kFieldTypeConstChange;
case kFieldTypeGroup:
return LazyDeoptimizeReason::kFieldTypeChange;
case kFieldRepresentationGroup:
return LazyDeoptimizeReason::kFieldRepresentationChange;
case kInitialMapChangedGroup:
return LazyDeoptimizeReason::kInitialMapChange;
case kAllocationSiteTenuringChangedGroup:
return LazyDeoptimizeReason::kAllocationSiteTenuringChange;
case kAllocationSiteTransitionChangedGroup:
return LazyDeoptimizeReason::kAllocationSiteTransitionChange;
case kContextCellChangedGroup:
return LazyDeoptimizeReason::kContextCellChange;
case kEmptyContextExtensionGroup:
return LazyDeoptimizeReason::kEmptyContextExtensionChange;
}
UNREACHABLE();
}
} // namespace internal
} // namespace v8