Martin Kustermann
31dd6683f8
Since the kernel reading helpers have been extended to not only work with a kernel blob in C heap, but also work based on a [TypedData] buffer in the VM heap, access to the [TypedData] buffer is on the hot path now. This hot path is slowing things down considerably, in particular due to NoSafepoingScope's. This CL removes a critical NoSafepoingScope when accessing the [TypedData] in read-only mode. It also allows passing in the [Thread] directly, to avoid TLS lookups. Issue https://github.com/dart-lang/sdk/issues/32603 Change-Id: I91955bea5cd4eddbbd21c5d3bc6813504c2cece9 Reviewed-on: https://dart-review.googlesource.com/47222 Commit-Queue: Martin Kustermann <kustermann@google.com> Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
104 lines
3.2 KiB
C++
104 lines
3.2 KiB
C++
// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#ifndef RUNTIME_VM_ALLOCATION_H_
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#define RUNTIME_VM_ALLOCATION_H_
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#include "platform/allocation.h"
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#include "platform/assert.h"
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#include "vm/base_isolate.h"
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#include "vm/globals.h"
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namespace dart {
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// Forward declarations.
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class Isolate;
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class Thread;
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// Stack resources subclass from this base class. The VM will ensure that the
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// destructors of these objects are called before the stack is unwound past the
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// objects location on the stack. Use stack resource objects if objects
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// need to be destroyed even in the case of exceptions when a Longjump is done
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// to a stack frame above the frame where these objects were allocated.
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class StackResource {
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public:
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explicit StackResource(Thread* thread) : thread_(NULL), previous_(NULL) {
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Init(thread);
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}
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virtual ~StackResource();
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// Convenient access to the isolate of the thread of this resource.
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Isolate* isolate() const;
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// The thread that owns this resource.
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Thread* thread() const { return thread_; }
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// Destroy stack resources of thread until top exit frame.
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static void Unwind(Thread* thread) { UnwindAbove(thread, NULL); }
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// Destroy stack resources of thread above new_top, exclusive.
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static void UnwindAbove(Thread* thread, StackResource* new_top);
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private:
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void Init(Thread* thread);
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Thread* thread_;
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StackResource* previous_;
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DISALLOW_ALLOCATION();
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DISALLOW_IMPLICIT_CONSTRUCTORS(StackResource);
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};
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// Zone allocated objects cannot be individually deallocated, but have
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// to rely on the destructor of Zone which is called when the Zone
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// goes out of scope to reclaim memory.
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class ZoneAllocated {
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public:
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ZoneAllocated() {}
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// Implicitly allocate the object in the current zone.
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void* operator new(uword size);
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// Allocate the object in the given zone, which must be the current zone.
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void* operator new(uword size, Zone* zone);
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// Ideally, the delete operator should be protected instead of
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// public, but unfortunately the compiler sometimes synthesizes
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// (unused) destructors for classes derived from ZoneObject, which
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// require the operator to be visible. MSVC requires the delete
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// operator to be public.
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// Disallow explicit deallocation of nodes. Nodes can only be
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// deallocated by invoking DeleteAll() on the zone they live in.
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void operator delete(void* pointer) { UNREACHABLE(); }
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private:
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DISALLOW_COPY_AND_ASSIGN(ZoneAllocated);
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};
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// Within a NoSafepointScope, the thread must not reach any safepoint. Used
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// around code that manipulates raw object pointers directly without handles.
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#if defined(DEBUG)
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class NoSafepointScope : public StackResource {
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public:
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explicit NoSafepointScope(Thread* thread = nullptr);
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~NoSafepointScope();
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private:
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DISALLOW_COPY_AND_ASSIGN(NoSafepointScope);
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};
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#else // defined(DEBUG)
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class NoSafepointScope : public ValueObject {
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public:
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explicit NoSafepointScope(Thread* thread = nullptr) {}
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private:
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DISALLOW_COPY_AND_ASSIGN(NoSafepointScope);
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};
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#endif // defined(DEBUG)
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} // namespace dart
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#endif // RUNTIME_VM_ALLOCATION_H_
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