1 files changed, 63 insertions, 87 deletions

diff --git a/Source/JavaScriptCore/interpreter/JSStack.cpp b/Source/JavaScriptCore/interpreter/JSStack.cpp
index 6e441dfd5..8b73d3cc9 100644
--- a/Source/JavaScriptCore/interpreter/JSStack.cpp
+++ b/Source/JavaScriptCore/interpreter/JSStack.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008, 2013, 2014, 2015 Apple Inc. All rights reserved.
+ * Copyright (C) 2008, 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,7 +10,7 @@
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
- * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
+ * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
@@ -31,154 +31,130 @@
 
 #include "ConservativeRoots.h"
 #include "Interpreter.h"
-#include "JSCInlines.h"
-#include "Options.h"
-#include <wtf/Lock.h>
+#include <wtf/PageBlock.h>
 
 namespace JSC {
 
-#if !ENABLE(JIT)
 static size_t committedBytesCount = 0;
 
+static Mutex& stackStatisticsMutex()
+{
+    DEFINE_STATIC_LOCAL(Mutex, staticMutex, ());
+    return staticMutex;
+}    
+
 static size_t commitSize()
 {
-    static size_t size = std::max<size_t>(16 * 1024, pageSize());
+    static size_t size = 0;
+    if (!size)
+        size = std::max(16 * 1024, static_cast<int>(WTF::pageSize()));
     return size;
 }
 
-static StaticLock stackStatisticsMutex;
-#endif // !ENABLE(JIT)
-
-JSStack::JSStack(VM& vm)
+JSStack::JSStack(VM& vm, size_t capacity)
     : m_vm(vm)
-    , m_topCallFrame(vm.topCallFrame)
-#if !ENABLE(JIT)
     , m_end(0)
-    , m_reservedZoneSizeInRegisters(0)
-#endif
+    , m_topCallFrame(vm.topCallFrame)
 {
-#if !ENABLE(JIT)
-    size_t capacity = Options::maxPerThreadStackUsage();
     ASSERT(capacity && isPageAligned(capacity));
 
-    m_reservation = PageReservation::reserve(WTF::roundUpToMultipleOf(commitSize(), capacity), OSAllocator::JSVMStackPages);
-    setStackLimit(highAddress());
-    m_commitTop = highAddress();
-    
-    m_lastStackTop = baseOfStack();
-#endif // !ENABLE(JIT)
+    m_reservation = PageReservation::reserve(roundUpAllocationSize(capacity * sizeof(Register), commitSize()), OSAllocator::JSVMStackPages);
+    updateStackLimit(highAddress());
+    m_commitEnd = highAddress();
+
+    disableErrorStackReserve();
 
     m_topCallFrame = 0;
 }
 
-#if !ENABLE(JIT)
 JSStack::~JSStack()
 {
-    ptrdiff_t sizeToDecommit = reinterpret_cast<char*>(highAddress()) - reinterpret_cast<char*>(m_commitTop);
-    m_reservation.decommit(reinterpret_cast<void*>(m_commitTop), sizeToDecommit);
-    addToCommittedByteCount(-sizeToDecommit);
+    void* highAddress = reinterpret_cast<void*>(static_cast<char*>(m_reservation.base()) + m_reservation.size());
+    m_reservation.decommit(reinterpret_cast<void*>(m_commitEnd), reinterpret_cast<intptr_t>(highAddress) - reinterpret_cast<intptr_t>(m_commitEnd));
+    addToCommittedByteCount(-(reinterpret_cast<intptr_t>(highAddress) - reinterpret_cast<intptr_t>(m_commitEnd)));
     m_reservation.deallocate();
 }
 
-bool JSStack::growSlowCase(Register* newTopOfStack)
+bool JSStack::growSlowCase(Register* newEnd)
 {
-    Register* newTopOfStackWithReservedZone = newTopOfStack - m_reservedZoneSizeInRegisters;
-
     // If we have already committed enough memory to satisfy this request,
     // just update the end pointer and return.
-    if (newTopOfStackWithReservedZone >= m_commitTop) {
-        setStackLimit(newTopOfStack);
+    if (newEnd >= m_commitEnd) {
+        updateStackLimit(newEnd);
         return true;
     }
 
     // Compute the chunk size of additional memory to commit, and see if we
     // have it is still within our budget. If not, we'll fail to grow and
     // return false.
-    ptrdiff_t delta = reinterpret_cast<char*>(m_commitTop) - reinterpret_cast<char*>(newTopOfStackWithReservedZone);
-    delta = WTF::roundUpToMultipleOf(commitSize(), delta);
-    Register* newCommitTop = m_commitTop - (delta / sizeof(Register));
-    if (newCommitTop < reservationTop())
+    long delta = roundUpAllocationSize(reinterpret_cast<char*>(m_commitEnd) - reinterpret_cast<char*>(newEnd), commitSize());
+    if (reinterpret_cast<char*>(m_commitEnd) - delta <= reinterpret_cast<char*>(m_useableEnd))
         return false;
 
-    // Otherwise, the growth is still within our budget. Commit it and return true.
-    m_reservation.commit(newCommitTop, delta);
+    // Otherwise, the growth is still within our budget. Go ahead and commit
+    // it and return true.
+    m_reservation.commit(reinterpret_cast<char*>(m_commitEnd) - delta, delta);
     addToCommittedByteCount(delta);
-    m_commitTop = newCommitTop;
-    setStackLimit(newTopOfStack);
+    m_commitEnd = reinterpret_cast_ptr<Register*>(reinterpret_cast<char*>(m_commitEnd) - delta);
+    updateStackLimit(newEnd);
     return true;
 }
 
-void JSStack::gatherConservativeRoots(ConservativeRoots& conservativeRoots, JITStubRoutineSet& jitStubRoutines, CodeBlockSet& codeBlocks)
+void JSStack::gatherConservativeRoots(ConservativeRoots& conservativeRoots)
 {
-    conservativeRoots.add(topOfStack() + 1, highAddress(), jitStubRoutines, codeBlocks);
+    conservativeRoots.add(getBaseOfStack(), getTopOfStack());
 }
 
-void JSStack::sanitizeStack()
+void JSStack::gatherConservativeRoots(ConservativeRoots& conservativeRoots, JITStubRoutineSet& jitStubRoutines, CodeBlockSet& codeBlocks)
 {
-#if !ASAN_ENABLED
-    ASSERT(topOfStack() <= baseOfStack());
-    
-    if (m_lastStackTop < topOfStack()) {
-        char* begin = reinterpret_cast<char*>(m_lastStackTop + 1);
-        char* end = reinterpret_cast<char*>(topOfStack() + 1);
-        memset(begin, 0, end - begin);
-    }
-    
-    m_lastStackTop = topOfStack();
-#endif
+    conservativeRoots.add(getBaseOfStack(), getTopOfStack(), jitStubRoutines, codeBlocks);
 }
 
 void JSStack::releaseExcessCapacity()
 {
-    Register* highAddressWithReservedZone = highAddress() - m_reservedZoneSizeInRegisters;
-    ptrdiff_t delta = reinterpret_cast<char*>(highAddressWithReservedZone) - reinterpret_cast<char*>(m_commitTop);
-    m_reservation.decommit(m_commitTop, delta);
+    ptrdiff_t delta = reinterpret_cast<uintptr_t>(highAddress()) - reinterpret_cast<uintptr_t>(m_commitEnd);
+    m_reservation.decommit(m_commitEnd, delta);
     addToCommittedByteCount(-delta);
-    m_commitTop = highAddressWithReservedZone;
+    m_commitEnd = highAddress();
 }
 
-void JSStack::addToCommittedByteCount(long byteCount)
+void JSStack::initializeThreading()
 {
-    LockHolder locker(stackStatisticsMutex);
-    ASSERT(static_cast<long>(committedBytesCount) + byteCount > -1);
-    committedBytesCount += byteCount;
+    stackStatisticsMutex();
 }
 
-void JSStack::setReservedZoneSize(size_t reservedZoneSize)
+size_t JSStack::committedByteCount()
 {
-    m_reservedZoneSizeInRegisters = reservedZoneSize / sizeof(Register);
-    if (m_commitTop >= (m_end + 1) - m_reservedZoneSizeInRegisters)
-        growSlowCase(m_end + 1);
+    MutexLocker locker(stackStatisticsMutex());
+    return committedBytesCount;
 }
-#endif // !ENABLE(JIT)
 
-#if ENABLE(JIT)
-Register* JSStack::lowAddress() const
+void JSStack::addToCommittedByteCount(long byteCount)
 {
-    ASSERT(wtfThreadData().stack().isGrowingDownward());
-    return reinterpret_cast<Register*>(m_vm.stackLimit());
+    MutexLocker locker(stackStatisticsMutex());
+    ASSERT(static_cast<long>(committedBytesCount) + byteCount > -1);
+    committedBytesCount += byteCount;
 }
 
-Register* JSStack::highAddress() const
+void JSStack::enableErrorStackReserve()
 {
-    ASSERT(wtfThreadData().stack().isGrowingDownward());
-    return reinterpret_cast<Register*>(wtfThreadData().stack().origin());
+    m_useableEnd = reservationEnd();
 }
-#endif // ENABLE(JIT)
 
-size_t JSStack::committedByteCount()
+void JSStack::disableErrorStackReserve()
 {
-#if !ENABLE(JIT)
-    LockHolder locker(stackStatisticsMutex);
-    return committedBytesCount;
-#else
-    // When using the C stack, we don't know how many stack pages are actually
-    // committed. So, we use the current stack usage as an estimate.
-    ASSERT(wtfThreadData().stack().isGrowingDownward());
-    int8_t* current = reinterpret_cast<int8_t*>(&current);
-    int8_t* high = reinterpret_cast<int8_t*>(wtfThreadData().stack().origin());
-    return high - current;
-#endif
+    char* useableEnd = reinterpret_cast<char*>(reservationEnd()) + commitSize();
+    m_useableEnd = reinterpret_cast_ptr<Register*>(useableEnd);
+
+    // By the time we get here, we are guaranteed to be destructing the last
+    // Interpreter::ErrorHandlingMode that enabled this reserve in the first
+    // place. That means the stack space beyond m_useableEnd before we
+    // enabled the reserve was not previously in use. Hence, it is safe to
+    // shrink back to that m_useableEnd.
+    if (m_end < m_useableEnd) {
+        ASSERT(m_topCallFrame->frameExtent() >= m_useableEnd);
+        shrink(m_useableEnd);
+    }
 }
 
 } // namespace JSC