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// Copyright 2022 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/wasm/stacks.h"
namespace v8::internal::wasm {
// static
StackMemory* StackMemory::GetCurrentStackView(Isolate* isolate) {
byte* limit = reinterpret_cast<byte*>(isolate->stack_guard()->real_jslimit());
return new StackMemory(isolate, limit);
}
StackMemory::~StackMemory() {
if (v8_flags.trace_wasm_stack_switching) {
PrintF("Delete stack #%d\n", id_);
}
PageAllocator* allocator = GetPlatformPageAllocator();
if (owned_) allocator->DecommitPages(limit_, size_);
// We don't need to handle removing the last stack from the list (next_ ==
// this). This only happens on isolate tear down, otherwise there is always
// at least one reachable stack (the active stack).
isolate_->wasm_stacks() = next_;
prev_->next_ = next_;
next_->prev_ = prev_;
}
void StackMemory::Add(StackMemory* stack) {
stack->next_ = this->next_;
stack->prev_ = this;
this->next_->prev_ = stack;
this->next_ = stack;
}
StackMemory::StackMemory(Isolate* isolate) : isolate_(isolate), owned_(true) {
static std::atomic<int> next_id(1);
id_ = next_id.fetch_add(1);
PageAllocator* allocator = GetPlatformPageAllocator();
int kJsStackSizeKB = v8_flags.wasm_stack_switching_stack_size;
size_ = (kJsStackSizeKB + kJSLimitOffsetKB) * KB;
size_ = RoundUp(size_, allocator->AllocatePageSize());
limit_ = static_cast<byte*>(
allocator->AllocatePages(nullptr, size_, allocator->AllocatePageSize(),
PageAllocator::kReadWrite));
if (v8_flags.trace_wasm_stack_switching) {
PrintF("Allocate stack #%d (limit: %p, base: %p)\n", id_, limit_,
limit_ + size_);
}
}
// Overload to represent a view of the libc stack.
StackMemory::StackMemory(Isolate* isolate, byte* limit)
: isolate_(isolate),
limit_(limit),
size_(v8_flags.stack_size * KB),
owned_(false) {
id_ = 0;
}
} // namespace v8::internal::wasm
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