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From 7b6fbcd0a6700db498ad55db046ecda92c8ee8c1 Mon Sep 17 00:00:00 2001
From: Nikolaos Papaspyrou <nikolaos@chromium.org>
Date: Sun, 29 Jan 2023 17:18:08 +0100
Subject: [PATCH] Merge: [heap] Move the Stack object from ThreadLocalTop to
Isolate
This is just for nodejs, do not backmerge to 11.0.
(cherry picked from commit 1e4b71d99fea5ea6bb4bf6420585a7819872bb0f)
> Change-Id: I026a35af3bc6999a09b21f277756d4454c086343
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4152476
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Omer Katz <omerkatz@chromium.org>
> Commit-Queue: Nikolaos Papaspyrou <nikolaos@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#85445}
Stack information is thread-specific and, until now, it was stored in a
field in ThreadLocalTop. This CL moves stack information to the isolate
and makes sure to update the stack start whenever a main thread enters
the isolate. At the same time, the Stack object is refactored and
simplified.
As a side effect, after removing the Stack object, ThreadLocalTop
satisfies the std::standard_layout trait; this fixes some issues
observed with different C++ compilers.
Bug: v8:13630
Bug: v8:13257
Change-Id: I4be1f04fe90699e1a6e456dad3e0dd623851acce
---
src/execution/isolate.cc | 36 +++++++++++++++----------------
src/execution/isolate.h | 6 ++++++
src/execution/thread-local-top.cc | 2 --
src/execution/thread-local-top.h | 6 +-----
src/heap/heap.cc | 4 +---
5 files changed, 25 insertions(+), 29 deletions(-)
diff --git a/src/execution/isolate.cc b/src/execution/isolate.cc
index 4edf364e0a..be4fd400d2 100644
--- a/v8/src/execution/isolate.cc
+++ b/v8/src/execution/isolate.cc
@@ -3074,22 +3074,23 @@ void Isolate::AddSharedWasmMemory(Handle<WasmMemoryObject> memory_object) {
void Isolate::RecordStackSwitchForScanning() {
Object current = root(RootIndex::kActiveContinuation);
DCHECK(!current.IsUndefined());
- thread_local_top()->stack_.ClearStackSegments();
- wasm::StackMemory* stack = Managed<wasm::StackMemory>::cast(
- WasmContinuationObject::cast(current).stack())
- .get()
- .get();
+ stack().ClearStackSegments();
+ wasm::StackMemory* wasm_stack =
+ Managed<wasm::StackMemory>::cast(
+ WasmContinuationObject::cast(current).stack())
+ .get()
+ .get();
current = WasmContinuationObject::cast(current).parent();
- thread_local_top()->stack_.SetStackStart(
- reinterpret_cast<void*>(stack->base()));
+ heap()->SetStackStart(reinterpret_cast<void*>(wasm_stack->base()));
// We don't need to add all inactive stacks. Only the ones in the active chain
// may contain cpp heap pointers.
while (!current.IsUndefined()) {
auto cont = WasmContinuationObject::cast(current);
- auto* stack = Managed<wasm::StackMemory>::cast(cont.stack()).get().get();
- thread_local_top()->stack_.AddStackSegment(
- reinterpret_cast<const void*>(stack->base()),
- reinterpret_cast<const void*>(stack->jmpbuf()->sp));
+ auto* wasm_stack =
+ Managed<wasm::StackMemory>::cast(cont.stack()).get().get();
+ stack().AddStackSegment(
+ reinterpret_cast<const void*>(wasm_stack->base()),
+ reinterpret_cast<const void*>(wasm_stack->jmpbuf()->sp));
current = cont.parent();
}
}
@@ -3377,20 +3378,13 @@ void Isolate::Delete(Isolate* isolate) {
Isolate* saved_isolate = isolate->TryGetCurrent();
SetIsolateThreadLocals(isolate, nullptr);
isolate->set_thread_id(ThreadId::Current());
- isolate->thread_local_top()->stack_ =
- saved_isolate ? std::move(saved_isolate->thread_local_top()->stack_)
- : ::heap::base::Stack(base::Stack::GetStackStart());
+ isolate->heap()->SetStackStart(base::Stack::GetStackStart());
bool owns_shared_isolate = isolate->owns_shared_isolate_;
Isolate* maybe_shared_isolate = isolate->shared_isolate_;
isolate->Deinit();
- // Restore the saved isolate's stack.
- if (saved_isolate)
- saved_isolate->thread_local_top()->stack_ =
- std::move(isolate->thread_local_top()->stack_);
-
#ifdef DEBUG
non_disposed_isolates_--;
#endif // DEBUG
@@ -4647,6 +4641,10 @@ bool Isolate::Init(SnapshotData* startup_snapshot_data,
void Isolate::Enter() {
Isolate* current_isolate = nullptr;
PerIsolateThreadData* current_data = CurrentPerIsolateThreadData();
+
+ // Set the stack start for the main thread that enters the isolate.
+ heap()->SetStackStart(base::Stack::GetStackStart());
+
if (current_data != nullptr) {
current_isolate = current_data->isolate_;
DCHECK_NOT_NULL(current_isolate);
diff --git a/src/execution/isolate.h b/src/execution/isolate.h
index a32f999fe5..1cb6e10661 100644
--- a/v8/src/execution/isolate.h
+++ b/v8/src/execution/isolate.h
@@ -32,6 +32,7 @@
#include "src/execution/stack-guard.h"
#include "src/handles/handles.h"
#include "src/handles/traced-handles.h"
+#include "src/heap/base/stack.h"
#include "src/heap/factory.h"
#include "src/heap/heap.h"
#include "src/heap/read-only-heap.h"
@@ -2022,6 +2023,8 @@ class V8_EXPORT_PRIVATE Isolate final : private HiddenFactory {
SimulatorData* simulator_data() { return simulator_data_; }
#endif
+ ::heap::base::Stack& stack() { return stack_; }
+
#ifdef V8_ENABLE_WEBASSEMBLY
wasm::StackMemory*& wasm_stacks() { return wasm_stacks_; }
// Update the thread local's Stack object so that it is aware of the new stack
@@ -2520,6 +2523,9 @@ class V8_EXPORT_PRIVATE Isolate final : private HiddenFactory {
// The mutex only guards adding pages, the retrieval is signal safe.
base::Mutex code_pages_mutex_;
+ // Stack information for the main thread.
+ ::heap::base::Stack stack_;
+
#ifdef V8_ENABLE_WEBASSEMBLY
wasm::StackMemory* wasm_stacks_;
#endif
diff --git a/src/execution/thread-local-top.cc b/src/execution/thread-local-top.cc
index 0d7071ddda..05cc20b8e4 100644
--- a/v8/src/execution/thread-local-top.cc
+++ b/v8/src/execution/thread-local-top.cc
@@ -37,14 +37,12 @@ void ThreadLocalTop::Clear() {
current_embedder_state_ = nullptr;
failed_access_check_callback_ = nullptr;
thread_in_wasm_flag_address_ = kNullAddress;
- stack_ = ::heap::base::Stack();
}
void ThreadLocalTop::Initialize(Isolate* isolate) {
Clear();
isolate_ = isolate;
thread_id_ = ThreadId::Current();
- stack_.SetStackStart(base::Stack::GetStackStart());
#if V8_ENABLE_WEBASSEMBLY
thread_in_wasm_flag_address_ = reinterpret_cast<Address>(
trap_handler::GetThreadInWasmThreadLocalAddress());
diff --git a/src/execution/thread-local-top.h b/src/execution/thread-local-top.h
index 43fec0a7df..989c817f31 100644
--- a/v8/src/execution/thread-local-top.h
+++ b/v8/src/execution/thread-local-top.h
@@ -10,7 +10,6 @@
#include "include/v8-unwinder.h"
#include "src/common/globals.h"
#include "src/execution/thread-id.h"
-#include "src/heap/base/stack.h"
#include "src/objects/contexts.h"
#include "src/utils/utils.h"
@@ -30,7 +29,7 @@ class ThreadLocalTop {
// TODO(all): This is not particularly beautiful. We should probably
// refactor this to really consist of just Addresses and 32-bit
// integer fields.
- static constexpr uint32_t kSizeInBytes = 30 * kSystemPointerSize;
+ static constexpr uint32_t kSizeInBytes = 25 * kSystemPointerSize;
// Does early low-level initialization that does not depend on the
// isolate being present.
@@ -147,9 +146,6 @@ class ThreadLocalTop {
// Address of the thread-local "thread in wasm" flag.
Address thread_in_wasm_flag_address_;
-
- // Stack information.
- ::heap::base::Stack stack_;
};
} // namespace internal
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 51a90ddcab..b5722ab6ec 100644
--- a/v8/src/heap/heap.cc
+++ b/v8/src/heap/heap.cc
@@ -5851,9 +5851,7 @@ void Heap::SetStackStart(void* stack_start) {
stack().SetStackStart(stack_start);
}
-::heap::base::Stack& Heap::stack() {
- return isolate_->thread_local_top()->stack_;
-}
+::heap::base::Stack& Heap::stack() { return isolate_->stack(); }
void Heap::RegisterExternallyReferencedObject(Address* location) {
Object object = TracedHandles::Mark(location, TracedHandles::MarkMode::kAll);
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