Changeset 189888 in webkit for trunk/Source/JavaScriptCore/heap/Heap.cpp

Timestamp:

Sep 16, 2015, 5:16:35 PM (10 years ago)

Author:

[email protected]

Message:

Remove obsolete code for deleting CodeBlocks
​https://bugs.webkit.org/show_bug.cgi?id=149231

Reviewed by Mark Lam.

• heap/Heap.cpp:

(JSC::Heap::deleteAllCodeBlocks): ASSERT that we're called in a valid
state, and do the compiler waiting ourselves instead of having our
caller do it. This is more appropriate to our new limited use.

(JSC::Heap::collectImpl):
(JSC::Heap::deleteOldCode): Deleted. Don't call deleteAllCodeBlocks
periodically because it's not such a good idea to delete everything
at once, and CodeBlocks now have a more precise individual policy for
when to delete. Also, this function used to fail all or nearly all of
the time because its invariants that we were not executing or compiling
could not be met.

• heap/Heap.h:

• jsc.cpp:

(GlobalObject::finishCreation):
(functionDeleteAllCompiledCode): Deleted.

• tests/stress/deleteAllCompiledCode.js: Removed. Removed this testing

code because it did not do what it thought it did. All of this code
was guaranteed to no-op since it would run JavaScript to call a function
that would return early because JavaScript was running.

• runtime/VM.cpp:

(JSC::VM::deleteAllCode): This code is simpler now becaue
heap.deleteAllCodeBlocks does some work for us.

• runtime/VMEntryScope.cpp:

(JSC::VMEntryScope::VMEntryScope): Don't delete code on VM entry. This
policy was old, and it dated back to a time when we

(a) couldn't run in the interpreter if compilation failed;

(b) didn't reduce the rate of compilation in response to executable
memory pressure;

(c) didn't throw away individual CodeBlocks automatically.

File:

• trunk/Source/JavaScriptCore/heap/Heap.cpp (modified) (5 diffs)

trunk/Source/JavaScriptCore/heap/Heap.cpp

@@ -347 +347 @@
     , m_lastFullGCLength(0.01)
     , m_lastEdenGCLength(0.01)
-    , m_lastCodeDiscardTime(WTF::monotonicallyIncreasingTime())
     , m_fullActivityCallback(GCActivityCallback::createFullTimer(this))
 #if ENABLE(GGC)
@@ -893 +892 @@
 void Heap::deleteAllCodeBlocks()
 {
-    // If JavaScript is running, it's not safe to delete JavaScript code, since
+    // If JavaScript is running, it's not safe to delete all JavaScript code, since
     // we'll end up returning to deleted code.
-    if (m_vm->entryScope)
-        return;
-    
-    // If we have things on any worklist, then don't delete code. This is kind of
-    // a weird heuristic. It's definitely not safe to throw away code that is on
-    // the worklist. But this change was made in a hurry so we just avoid throwing
-    // away any code if there is any code on any worklist. I suspect that this
-    // might not actually be too dumb: if there is code on worklists then that
-    // means that we are running some hot JS code right now. Maybe causing
-    // recompilations isn't a good idea.
+    RELEASE_ASSERT(!m_vm->entryScope);
+
 #if ENABLE(DFG_JIT)
-    for (unsigned i = DFG::numberOfWorklists(); i--;) {
-        if (DFG::Worklist* worklist = DFG::worklistForIndexOrNull(i)) {
-            if (worklist->isActiveForVM(*vm()))
-                return;
-        }
-    }
-#endif // ENABLE(DFG_JIT)
+    DFG::completeAllPlansForVM(*m_vm);
+#endif
 
     for (ExecutableBase* current : m_executables) {
@@ -983 +969 @@
     sweepAllLogicallyEmptyWeakBlocks();
 }
-
-static double minute = 60.0;
 
 NEVER_INLINE void Heap::collect(HeapOperation collectionType)
@@ -1036 +1020 @@
     }
 
-    deleteOldCode(gcStartTime);
     flushOldStructureIDTables();
     stopAllocation();
@@ -1124 +1107 @@
     if (m_edenActivityCallback)
         m_edenActivityCallback->willCollect();
-}
-
-void Heap::deleteOldCode(double gcStartTime)
-{
-    if (m_operationInProgress == EdenCollection)
-        return;
-
-    GCPHASE(DeleteOldCode);
-    if (gcStartTime - m_lastCodeDiscardTime > minute) {
-        m_vm->regExpCache()->deleteAllCode();
-        deleteAllCodeBlocks();
-        m_lastCodeDiscardTime = WTF::monotonicallyIncreasingTime();
-    }
 }