Modified: tags/Safari-601.1.8/Source/_javascript_Core/ChangeLog (175683 => 175684)
--- tags/Safari-601.1.8/Source/_javascript_Core/ChangeLog 2014-11-06 06:33:50 UTC (rev 175683)
+++ tags/Safari-601.1.8/Source/_javascript_Core/ChangeLog 2014-11-06 06:53:25 UTC (rev 175684)
@@ -1,3 +1,37 @@
+2014-11-05 Babak Shafiei <[email protected]>
+
+ Merge rr175653.
+
+ 2014-11-05 Mark Lam <[email protected]>
+
+ PutById inline caches should have a store barrier when it triggers a structure transition.
+ <https://webkit.org/b/138441>
+
+ Reviewed by Geoffrey Garen.
+
+ After r174025, we no longer insert DFG store barriers when the payload of a
+ PutById operation is not a cell. However, this can lead to a crash when we have
+ PutById inline cache code transitioning the structure and re-allocating the
+ butterfly of an old gen object. The lack of a store barrier in that inline
+ cache results in the old gen object not being noticed during an eden GC scan.
+ As a result, its newly allocated butterfly will not be kept alive, which leads
+ to a stale butterfly pointer and, eventually, a crash.
+
+ It is also possible that the new structure can be collected by the eden GC if
+ (at GC time):
+ 1. It is in the eden gen.
+ 2. The inline cache that installed it has been evicted.
+ 3. There are no live eden gen objects referring to it.
+
+ The chances of this should be more rare than the butterfly re-allocation, but
+ it is still possible. Hence, the fix is to always add a store barrier if the
+ inline caches performs a structure transition.
+
+ * jit/Repatch.cpp:
+ (JSC::emitPutTransitionStub):
+ - Added store barrier code based on SpeculativeJIT::storeToWriteBarrierBuffer()'s
+ implementation.
+
2014-11-04 Mark Lam <[email protected]>
Rename checkMarkByte() to jumpIfIsRememberedOrInEden().
Modified: tags/Safari-601.1.8/Source/_javascript_Core/jit/Repatch.cpp (175683 => 175684)
--- tags/Safari-601.1.8/Source/_javascript_Core/jit/Repatch.cpp 2014-11-06 06:33:50 UTC (rev 175683)
+++ tags/Safari-601.1.8/Source/_javascript_Core/jit/Repatch.cpp 2014-11-06 06:53:25 UTC (rev 175684)
@@ -1113,6 +1113,39 @@
}
#endif
+ ScratchBuffer* scratchBuffer = nullptr;
+
+#if ENABLE(GGC)
+ MacroAssembler::Call callFlushWriteBarrierBuffer;
+ MacroAssembler::Jump ownerIsRememberedOrInEden = stubJit.jumpIfIsRememberedOrInEden(baseGPR);
+ {
+ WriteBarrierBuffer* writeBarrierBuffer = &stubJit.vm()->heap.writeBarrierBuffer();
+ stubJit.move(MacroAssembler::TrustedImmPtr(writeBarrierBuffer), scratchGPR1);
+ stubJit.load32(MacroAssembler::Address(scratchGPR1, WriteBarrierBuffer::currentIndexOffset()), scratchGPR2);
+ MacroAssembler::Jump needToFlush =
+ stubJit.branch32(MacroAssembler::AboveOrEqual, scratchGPR2, MacroAssembler::Address(scratchGPR1, WriteBarrierBuffer::capacityOffset()));
+
+ stubJit.add32(MacroAssembler::TrustedImm32(1), scratchGPR2);
+ stubJit.store32(scratchGPR2, MacroAssembler::Address(scratchGPR1, WriteBarrierBuffer::currentIndexOffset()));
+
+ stubJit.loadPtr(MacroAssembler::Address(scratchGPR1, WriteBarrierBuffer::bufferOffset()), scratchGPR1);
+ // We use an offset of -sizeof(void*) because we already added 1 to scratchGPR2.
+ stubJit.storePtr(baseGPR, MacroAssembler::BaseIndex(scratchGPR1, scratchGPR2, MacroAssembler::ScalePtr, static_cast<int32_t>(-sizeof(void*))));
+
+ MacroAssembler::Jump doneWithBarrier = stubJit.jump();
+ needToFlush.link(&stubJit);
+
+ scratchBuffer = vm->scratchBufferForSize(allocator.desiredScratchBufferSizeForCall());
+ allocator.preserveUsedRegistersToScratchBufferForCall(stubJit, scratchBuffer, scratchGPR2);
+ stubJit.setupArgumentsWithExecState(baseGPR);
+ callFlushWriteBarrierBuffer = stubJit.call();
+ allocator.restoreUsedRegistersFromScratchBufferForCall(stubJit, scratchBuffer, scratchGPR2);
+
+ doneWithBarrier.link(&stubJit);
+ }
+ ownerIsRememberedOrInEden.link(&stubJit);
+#endif
+
MacroAssembler::Jump success;
MacroAssembler::Jump failure;
@@ -1133,7 +1166,8 @@
slowPath.link(&stubJit);
allocator.restoreReusedRegistersByPopping(stubJit);
- ScratchBuffer* scratchBuffer = vm->scratchBufferForSize(allocator.desiredScratchBufferSizeForCall());
+ if (!scratchBuffer)
+ scratchBuffer = vm->scratchBufferForSize(allocator.desiredScratchBufferSizeForCall());
allocator.preserveUsedRegistersToScratchBufferForCall(stubJit, scratchBuffer, scratchGPR1);
#if USE(JSVALUE64)
stubJit.setupArgumentsWithExecState(baseGPR, MacroAssembler::TrustedImmPtr(structure), MacroAssembler::TrustedImm32(slot.cachedOffset()), valueGPR);
@@ -1151,6 +1185,9 @@
patchBuffer.link(failure, failureLabel);
else
patchBuffer.link(failureCases, failureLabel);
+#if ENABLE(GGC)
+ patchBuffer.link(callFlushWriteBarrierBuffer, operationFlushWriteBarrierBuffer);
+#endif
if (structure->outOfLineCapacity() != oldStructure->outOfLineCapacity()) {
patchBuffer.link(operationCall, operationReallocateStorageAndFinishPut);
patchBuffer.link(successInSlowPath, stubInfo.callReturnLocation.labelAtOffset(stubInfo.patch.deltaCallToDone));
