Changeset 190522 in webkit for trunk/Source/JavaScriptCore/dfg/DFGPlan.h

Timestamp:

Oct 2, 2015, 2:16:20 PM (10 years ago)

Author:

[email protected]

Message:

Unreviewed, rolling back in r190450
​https://bugs.webkit.org/show_bug.cgi?id=149727

The cause of the crash was a CodeBlock, after surviving a call to
deleteAllCode by virtue of being in the remembered set, trying to mark
its inlined CodeBlocks via pointers from its inlined executables.
Since deleteAllCode clears those pointers, the CodeBlock would ASSERT.
(Any other choice to retain a CodeBlock after deleteAllCode -- for
example, conservative marking -- could trigger the same bug.)

The fix is for InlineCallFrame to point directly to its inlined CodeBlock
instead of pointing indirectly via an executable. This guarantees that
CodeBlocks are GC safe regardless of whether we've called deleteAllCode.

Restored changesets:

"CodeBlock should be a GC object"
​https://bugs.webkit.org/show_bug.cgi?id=149727
​http://trac.webkit.org/changeset/190450

File:

• trunk/Source/JavaScriptCore/dfg/DFGPlan.h (modified) (3 diffs)

trunk/Source/JavaScriptCore/dfg/DFGPlan.h

@@ -56 +56 @@
 struct Plan : public ThreadSafeRefCounted<Plan> {
     Plan(
-        PassRefPtr<CodeBlock> codeBlockToCompile, CodeBlock* profiledDFGCodeBlock,
+        CodeBlock* codeBlockToCompile, CodeBlock* profiledDFGCodeBlock,
         CompilationMode, unsigned osrEntryBytecodeIndex,
         const Operands<JSValue>& mustHandleValues);
@@ -72 +72 @@
     CompilationKey key();
     
-    void clearCodeBlockMarks();
+    void rememberCodeBlocks();
     void checkLivenessAndVisitChildren(SlotVisitor&);
     bool isKnownToBeLiveDuringGC();
@@ -78 +78 @@
     
     VM& vm;
-    RefPtr<CodeBlock> codeBlock;
-    RefPtr<CodeBlock> profiledDFGCodeBlock;
+
+    // These can be raw pointers because we visit them during every GC in checkLivenessAndVisitChildren.
+    CodeBlock* codeBlock;
+    CodeBlock* profiledDFGCodeBlock;
+
     CompilationMode mode;
     const unsigned osrEntryBytecodeIndex;