Changeset 161174 in webkit

Timestamp:

Dec 30, 2013 11:22:21 PM (10 years ago)

Author:

mark.lam@apple.com

Message:

CStack: Introduce tracking of the top VMEntryScope.
​https://bugs.webkit.org/show_bug.cgi?id=126334.

Not yet reviewed.

When we start measuring the stack usage of each VMEntryScope, we'll need
to know which VMEntryScope is the top (most recent) one, not just the
first one.

Also, for correctness, in JSStack::updateStackLimit(), when we set a new
jsStackLimit, we should set it on the top VMEntryScope, and not on the
first (oldest) one. This is because the 2 scopes may be on 2 different
thread stacks, and the most present stack limits only apply to the most
recent scope. That said, presently, VMEntryScope::updateStackLimits()
does not rely on any scope specific data yet. So, calling updateStackLimits()
on the oldest VMEntryScope hasn't manifested any issues yet. Regardless,
this is now fixed.

• interpreter/JSStack.cpp:

(JSC::JSStack::updateStackLimit):

• runtime/VM.cpp:

(JSC::VM::VM):

• runtime/VM.h:
• runtime/VMEntryScope.cpp:

(JSC::VMEntryScope::VMEntryScope):
(JSC::VMEntryScope::~VMEntryScope):

• runtime/VMEntryScope.h:

Location:

branches/jsCStack/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• interpreter/JSStack.cpp (modified) (1 diff)
• runtime/VM.cpp (modified) (1 diff)
• runtime/VM.h (modified) (1 diff)
• runtime/VMEntryScope.cpp (modified) (3 diffs)
• runtime/VMEntryScope.h (modified) (1 diff)

branches/jsCStack/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2013-12-30  Mark Lam  <mark.lam@apple.com>
+
+        CStack: Introduce tracking of the top VMEntryScope.
+        https://bugs.webkit.org/show_bug.cgi?id=126334.
+
+        Not yet reviewed.
+
+        When we start measuring the stack usage of each VMEntryScope, we'll need
+        to know which VMEntryScope is the top (most recent) one, not just the
+        first one.
+
+        Also, for correctness, in JSStack::updateStackLimit(), when we set a new
+        jsStackLimit, we should set it on the top VMEntryScope, and not on the
+        first (oldest) one. This is because the 2 scopes may be on 2 different
+        thread stacks, and the most present stack limits only apply to the most
+        recent scope. That said, presently, VMEntryScope::updateStackLimits()
+        does not rely on any scope specific data yet. So, calling updateStackLimits()
+        on the oldest VMEntryScope hasn't manifested any issues yet. Regardless,
+        this is now fixed.
+
+        * interpreter/JSStack.cpp:
+        (JSC::JSStack::updateStackLimit):
+        * runtime/VM.cpp:
+        (JSC::VM::VM):
+        * runtime/VM.h:
+        * runtime/VMEntryScope.cpp:
+        (JSC::VMEntryScope::VMEntryScope):
+        (JSC::VMEntryScope::~VMEntryScope):
+        * runtime/VMEntryScope.h:
+
 2013-12-30  Mark Lam  <mark.lam@apple.com>
 

branches/jsCStack/Source/JavaScriptCore/interpreter/JSStack.cpp

@@ -205 +205 @@
         disableErrorStackReserve();
 #endif
-    if (m_vm.firstEntryScope)
-        m_vm.firstEntryScope->updateStackLimits();
+    if (m_vm.topEntryScope)
+        m_vm.topEntryScope->updateStackLimits();
 }
 

branches/jsCStack/Source/JavaScriptCore/runtime/VM.cpp

@@ -200 +200 @@
     , sizeOfLastScratchBuffer(0)
     , firstEntryScope(0)
+    , topEntryScope(0)
     , m_enabledProfiler(0)
     , m_regExpCache(new RegExpCache(this))

branches/jsCStack/Source/JavaScriptCore/runtime/VM.h

@@ -428 +428 @@
 
         VMEntryScope* firstEntryScope;
+        VMEntryScope* topEntryScope;
 
         HashSet<JSObject*> stringRecursionCheckVisitedObjects;

branches/jsCStack/Source/JavaScriptCore/runtime/VMEntryScope.cpp

@@ -37 +37 @@
     , m_globalObject(globalObject)
     , m_prevFirstEntryScope(vm.firstEntryScope)
+    , m_prevTopEntryScope(vm.topEntryScope)
     , m_prevStackLimit(vm.stackLimit())
 #if !ENABLE(LLINT_C_LOOP)
@@ -54 +55 @@
         vm.resetDateCache();
     }
-    // Clear the exception stack between entries
+    vm.topEntryScope = this;
+
+    // Clear the captured exception stack between entries
     vm.clearExceptionStack();
 
@@ -64 +67 @@
 {
     m_vm.firstEntryScope = m_prevFirstEntryScope;
+    m_vm.topEntryScope = m_prevTopEntryScope;
     m_vm.setStackLimit(m_prevStackLimit);
 #if !ENABLE(LLINT_C_LOOP)

branches/jsCStack/Source/JavaScriptCore/runtime/VMEntryScope.h

@@ -58 +58 @@
     // The following pointers may point to a different thread's stack.
     VMEntryScope* m_prevFirstEntryScope;
+    VMEntryScope* m_prevTopEntryScope;
     void* m_prevStackLimit;
 #if !ENABLE(LLINT_C_LOOP)