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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/183959">183959</a></dd>
<dt>Author</dt> <dd>ggaren@apple.com</dd>
<dt>Date</dt> <dd>2015-05-07 16:29:15 -0700 (Thu, 07 May 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>Release assert in com.apple.WebKit.WebContent under JavaScriptCore: JSC::JSONProtoFuncStringify
https://bugs.webkit.org/show_bug.cgi?id=144758
Reviewed by Andreas Kling.
This was an out-of-memory error when trying to shrink a string builder.
bmalloc was missing the optimization that allowed realloc() to shrink
without copying. So, let's add it.
* bmalloc/Allocator.cpp:
(bmalloc::Allocator::reallocate): Added Large and XLarge cases for
shrinking without copying. This isn't possible for small and medium
objects, and probably not very profitable, either.
* bmalloc/Heap.cpp:
(bmalloc::Heap::findXLarge):
(bmalloc::Heap::deallocateXLarge):
* bmalloc/Heap.h: Refactored this code to return a reference to an
XLarge range. This makes the code reusable, and also makes it easier
for realloc() to update metadata.
* bmalloc/LargeObject.h:
(bmalloc::LargeObject::split): Allow allocated objects to split because
that's what realloc() wants to do, and there's nothing intrinsically
wrong with it.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourcebmallocChangeLog">trunk/Source/bmalloc/ChangeLog</a></li>
<li><a href="#trunkSourcebmallocbmallocAllocatorcpp">trunk/Source/bmalloc/bmalloc/Allocator.cpp</a></li>
<li><a href="#trunkSourcebmallocbmallocDeallocatorcpp">trunk/Source/bmalloc/bmalloc/Deallocator.cpp</a></li>
<li><a href="#trunkSourcebmallocbmallocHeapcpp">trunk/Source/bmalloc/bmalloc/Heap.cpp</a></li>
<li><a href="#trunkSourcebmallocbmallocHeaph">trunk/Source/bmalloc/bmalloc/Heap.h</a></li>
<li><a href="#trunkSourcebmallocbmallocLargeObjecth">trunk/Source/bmalloc/bmalloc/LargeObject.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourcebmallocChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/ChangeLog (183958 => 183959)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/ChangeLog 2015-05-07 23:08:53 UTC (rev 183958)
+++ trunk/Source/bmalloc/ChangeLog 2015-05-07 23:29:15 UTC (rev 183959)
</span><span class="lines">@@ -1,3 +1,31 @@
</span><ins>+2015-05-07 Geoffrey Garen <ggaren@apple.com>
+
+ Release assert in com.apple.WebKit.WebContent under JavaScriptCore: JSC::JSONProtoFuncStringify
+ https://bugs.webkit.org/show_bug.cgi?id=144758
+
+ Reviewed by Andreas Kling.
+
+ This was an out-of-memory error when trying to shrink a string builder.
+ bmalloc was missing the optimization that allowed realloc() to shrink
+ without copying. So, let's add it.
+
+ * bmalloc/Allocator.cpp:
+ (bmalloc::Allocator::reallocate): Added Large and XLarge cases for
+ shrinking without copying. This isn't possible for small and medium
+ objects, and probably not very profitable, either.
+
+ * bmalloc/Heap.cpp:
+ (bmalloc::Heap::findXLarge):
+ (bmalloc::Heap::deallocateXLarge):
+ * bmalloc/Heap.h: Refactored this code to return a reference to an
+ XLarge range. This makes the code reusable, and also makes it easier
+ for realloc() to update metadata.
+
+ * bmalloc/LargeObject.h:
+ (bmalloc::LargeObject::split): Allow allocated objects to split because
+ that's what realloc() wants to do, and there's nothing intrinsically
+ wrong with it.
+
</ins><span class="cx"> 2015-05-07 Dan Bernstein <mitz@apple.com>
</span><span class="cx">
</span><span class="cx"> <rdar://problem/19317140> [Xcode] Remove usage of AspenFamily.xcconfig in Source/
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocAllocatorcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/Allocator.cpp (183958 => 183959)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/Allocator.cpp 2015-05-07 23:08:53 UTC (rev 183958)
+++ trunk/Source/bmalloc/bmalloc/Allocator.cpp 2015-05-07 23:29:15 UTC (rev 183959)
</span><span class="lines">@@ -112,10 +112,6 @@
</span><span class="cx"> if (!m_isBmallocEnabled)
</span><span class="cx"> return realloc(object, newSize);
</span><span class="cx">
</span><del>- void* result = allocate(newSize);
- if (!object)
- return result;
-
</del><span class="cx"> size_t oldSize = 0;
</span><span class="cx"> switch (objectType(object)) {
</span><span class="cx"> case Small: {
</span><span class="lines">@@ -129,20 +125,48 @@
</span><span class="cx"> break;
</span><span class="cx"> }
</span><span class="cx"> case Large: {
</span><del>- std::lock_guard<StaticMutex> lock(PerProcess<Heap>::mutex());
</del><ins>+ std::unique_lock<StaticMutex> lock(PerProcess<Heap>::mutex());
</ins><span class="cx"> LargeObject largeObject(object);
</span><span class="cx"> oldSize = largeObject.size();
</span><ins>+
+ if (newSize < oldSize && newSize > mediumMax) {
+ newSize = roundUpToMultipleOf<largeAlignment>(newSize);
+ if (oldSize - newSize >= largeMin) {
+ std::pair<LargeObject, LargeObject> split = largeObject.split(newSize);
+
+ lock.unlock();
+ m_deallocator.deallocate(split.second.begin());
+ lock.lock();
+ }
+ return object;
+ }
</ins><span class="cx"> break;
</span><span class="cx"> }
</span><span class="cx"> case XLarge: {
</span><del>- std::lock_guard<StaticMutex> lock(PerProcess<Heap>::mutex());
- Range range = PerProcess<Heap>::getFastCase()->findXLarge(lock, object);
- RELEASE_BASSERT(range);
</del><ins>+ BASSERT(objectType(nullptr) == XLarge);
+ if (!object)
+ break;
+
+ std::unique_lock<StaticMutex> lock(PerProcess<Heap>::mutex());
+ Range& range = PerProcess<Heap>::getFastCase()->findXLarge(lock, object);
</ins><span class="cx"> oldSize = range.size();
</span><ins>+
+ if (newSize < oldSize && newSize > largeMax) {
+ newSize = roundUpToMultipleOf<xLargeAlignment>(newSize);
+ if (oldSize - newSize >= xLargeAlignment) {
+ lock.unlock();
+ vmDeallocate(static_cast<char*>(object) + oldSize, oldSize - newSize);
+ lock.lock();
+
+ range = Range(object, newSize);
+ }
+ return object;
+ }
</ins><span class="cx"> break;
</span><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ void* result = allocate(newSize);
</ins><span class="cx"> size_t copySize = std::min(oldSize, newSize);
</span><span class="cx"> memcpy(result, object, copySize);
</span><span class="cx"> m_deallocator.deallocate(object);
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocDeallocatorcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/Deallocator.cpp (183958 => 183959)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/Deallocator.cpp 2015-05-07 23:08:53 UTC (rev 183958)
+++ trunk/Source/bmalloc/bmalloc/Deallocator.cpp 2015-05-07 23:29:15 UTC (rev 183959)
</span><span class="lines">@@ -99,6 +99,7 @@
</span><span class="cx"> return;
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ BASSERT(objectType(nullptr) == XLarge);
</ins><span class="cx"> if (!object)
</span><span class="cx"> return;
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocHeapcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/Heap.cpp (183958 => 183959)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/Heap.cpp 2015-05-07 23:08:53 UTC (rev 183958)
+++ trunk/Source/bmalloc/bmalloc/Heap.cpp 2015-05-07 23:29:15 UTC (rev 183959)
</span><span class="lines">@@ -306,7 +306,7 @@
</span><span class="cx"> return result;
</span><span class="cx"> }
</span><span class="cx">
</span><del>-Range Heap::findXLarge(std::lock_guard<StaticMutex>&, void* object)
</del><ins>+Range& Heap::findXLarge(std::unique_lock<StaticMutex>&, void* object)
</ins><span class="cx"> {
</span><span class="cx"> for (auto& range : m_xLargeObjects) {
</span><span class="cx"> if (range.begin() != object)
</span><span class="lines">@@ -314,23 +314,17 @@
</span><span class="cx"> return range;
</span><span class="cx"> }
</span><span class="cx">
</span><del>- return Range();
</del><ins>+ RELEASE_BASSERT(false);
+ return *static_cast<Range*>(nullptr); // Silence compiler error.
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void Heap::deallocateXLarge(std::unique_lock<StaticMutex>& lock, void* object)
</span><span class="cx"> {
</span><del>- for (auto& range : m_xLargeObjects) {
- if (range.begin() != object)
- continue;
</del><ins>+ Range toDeallocate = m_xLargeObjects.pop(&findXLarge(lock, object));
</ins><span class="cx">
</span><del>- Range toDeallocate = m_xLargeObjects.pop(&range);
-
- lock.unlock();
- vmDeallocate(toDeallocate.begin(), toDeallocate.size());
- lock.lock();
-
- break;
- }
</del><ins>+ lock.unlock();
+ vmDeallocate(toDeallocate.begin(), toDeallocate.size());
+ lock.lock();
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void* Heap::allocateLarge(std::lock_guard<StaticMutex>&, LargeObject& largeObject, size_t size)
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocHeaph"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/Heap.h (183958 => 183959)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/Heap.h 2015-05-07 23:08:53 UTC (rev 183958)
+++ trunk/Source/bmalloc/bmalloc/Heap.h 2015-05-07 23:29:15 UTC (rev 183959)
</span><span class="lines">@@ -66,7 +66,7 @@
</span><span class="cx"> void* allocateXLarge(std::lock_guard<StaticMutex>&, size_t);
</span><span class="cx"> void* allocateXLarge(std::lock_guard<StaticMutex>&, size_t alignment, size_t);
</span><span class="cx"> void* tryAllocateXLarge(std::lock_guard<StaticMutex>&, size_t alignment, size_t);
</span><del>- Range findXLarge(std::lock_guard<StaticMutex>&, void*);
</del><ins>+ Range& findXLarge(std::unique_lock<StaticMutex>&, void*);
</ins><span class="cx"> void deallocateXLarge(std::unique_lock<StaticMutex>&, void*);
</span><span class="cx">
</span><span class="cx"> void scavenge(std::unique_lock<StaticMutex>&, std::chrono::milliseconds sleepDuration);
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocLargeObjecth"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/LargeObject.h (183958 => 183959)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/LargeObject.h 2015-05-07 23:08:53 UTC (rev 183958)
+++ trunk/Source/bmalloc/bmalloc/LargeObject.h 2015-05-07 23:29:15 UTC (rev 183959)
</span><span class="lines">@@ -206,8 +206,6 @@
</span><span class="cx">
</span><span class="cx"> inline std::pair<LargeObject, LargeObject> LargeObject::split(size_t size) const
</span><span class="cx"> {
</span><del>- BASSERT(isFree());
-
</del><span class="cx"> Range split(begin(), size);
</span><span class="cx"> Range leftover = Range(split.end(), this->size() - size);
</span><span class="cx"> BASSERT(leftover.size() >= largeMin);
</span></span></pre>
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