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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/243667">243667</a></dd>
<dt>Author</dt> <dd>ysuzuki@apple.com</dd>
<dt>Date</dt> <dd>2019-03-29 16:33:31 -0700 (Fri, 29 Mar 2019)</dd>
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<h3>Log Message</h3>
<pre>[JSC] Remove distancing for LargeAllocation
https://bugs.webkit.org/show_bug.cgi?id=196335

Reviewed by Saam Barati.

In <a href="http://trac.webkit.org/projects/webkit/changeset/230226">r230226</a>, we removed distancing feature from our GC. This patch removes remaining distancing thing in LargeAllocation.

* heap/HeapCell.h:
* heap/LargeAllocation.cpp:
(JSC::LargeAllocation::tryCreate):
* heap/MarkedBlock.h:</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreheapHeapCellh">trunk/Source/JavaScriptCore/heap/HeapCell.h</a></li>
<li><a href="#trunkSourceJavaScriptCoreheapLargeAllocationcpp">trunk/Source/JavaScriptCore/heap/LargeAllocation.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoreheapMarkedBlockh">trunk/Source/JavaScriptCore/heap/MarkedBlock.h</a></li>
</ul>

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<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (243666 => 243667)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog    2019-03-29 22:18:59 UTC (rev 243666)
+++ trunk/Source/JavaScriptCore/ChangeLog       2019-03-29 23:33:31 UTC (rev 243667)
</span><span class="lines">@@ -1,3 +1,17 @@
</span><ins>+2019-03-29  Yusuke Suzuki  <ysuzuki@apple.com>
+
+        [JSC] Remove distancing for LargeAllocation
+        https://bugs.webkit.org/show_bug.cgi?id=196335
+
+        Reviewed by Saam Barati.
+
+        In r230226, we removed distancing feature from our GC. This patch removes remaining distancing thing in LargeAllocation.
+
+        * heap/HeapCell.h:
+        * heap/LargeAllocation.cpp:
+        (JSC::LargeAllocation::tryCreate):
+        * heap/MarkedBlock.h:
+
</ins><span class="cx"> 2019-03-29  Myles C. Maxfield  <mmaxfield@apple.com>
</span><span class="cx"> 
</span><span class="cx">         Delete WebMetal implementation in favor of WebGPU
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreheapHeapCellh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/heap/HeapCell.h (243666 => 243667)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/heap/HeapCell.h      2019-03-29 22:18:59 UTC (rev 243666)
+++ trunk/Source/JavaScriptCore/heap/HeapCell.h 2019-03-29 23:33:31 UTC (rev 243667)
</span><span class="lines">@@ -37,8 +37,6 @@
</span><span class="cx"> class VM;
</span><span class="cx"> struct CellAttributes;
</span><span class="cx"> 
</span><del>-static constexpr unsigned minimumDistanceBetweenCellsFromDifferentOrigins = sizeof(void*) == 8 ? 304 : 288;
-
</del><span class="cx"> class HeapCell {
</span><span class="cx"> public:
</span><span class="cx">     enum Kind : int8_t {
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreheapLargeAllocationcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/heap/LargeAllocation.cpp (243666 => 243667)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/heap/LargeAllocation.cpp     2019-03-29 22:18:59 UTC (rev 243666)
+++ trunk/Source/JavaScriptCore/heap/LargeAllocation.cpp        2019-03-29 23:33:31 UTC (rev 243667)
</span><span class="lines">@@ -39,18 +39,12 @@
</span><span class="cx">     if (validateDFGDoesGC)
</span><span class="cx">         RELEASE_ASSERT(heap.expectDoesGC());
</span><span class="cx"> 
</span><del>-    // This includes padding at the end of the allocation to maintain the distancing constraint.
-    constexpr size_t distancing = minimumDistanceBetweenCellsFromDifferentOrigins;
-    size_t sizeBeforeDistancing = headerSize() + size;
-    size_t sizeIncludingDistancing = sizeBeforeDistancing + distancing;
</del><ins>+    size_t allocationSize = headerSize() + size;
</ins><span class="cx">     
</span><del>-    void* space = subspace->alignedMemoryAllocator()->tryAllocateAlignedMemory(alignment, sizeIncludingDistancing);
</del><ins>+    void* space = subspace->alignedMemoryAllocator()->tryAllocateAlignedMemory(alignment, allocationSize);
</ins><span class="cx">     if (!space)
</span><span class="cx">         return nullptr;
</span><span class="cx">     
</span><del>-    // Make sure that the padding does not contain useful things.
-    memset(static_cast<char*>(space) + sizeBeforeDistancing, 0, distancing);
-    
</del><span class="cx">     if (scribbleFreeCells())
</span><span class="cx">         scribble(space, size);
</span><span class="cx">     return new (NotNull, space) LargeAllocation(heap, size, subspace);
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreheapMarkedBlockh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/heap/MarkedBlock.h (243666 => 243667)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/heap/MarkedBlock.h   2019-03-29 22:18:59 UTC (rev 243666)
+++ trunk/Source/JavaScriptCore/heap/MarkedBlock.h      2019-03-29 23:33:31 UTC (rev 243667)
</span><span class="lines">@@ -304,7 +304,6 @@
</span><span class="cx">     static constexpr size_t footerSize = blockSize - payloadSize;
</span><span class="cx"> 
</span><span class="cx">     static_assert(payloadSize == ((blockSize - sizeof(MarkedBlock::Footer)) & ~(atomSize - 1)), "Payload size computed the alternate way should give the same result");
</span><del>-    static_assert(footerSize >= minimumDistanceBetweenCellsFromDifferentOrigins, "Footer is not big enough to create the necessary distance between objects from different origins");
</del><span class="cx">     
</span><span class="cx">     static MarkedBlock::Handle* tryCreate(Heap&, AlignedMemoryAllocator*);
</span><span class="cx">         
</span></span></pre>
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