Totally forget deallocated SDNodes in SDDbgInfo. What would happen before that commit is that the SDDbgValues associated with a deallocated SDNode would be marked Invalidated, but SDDbgInfo would keep a map entry keyed by the SDNode pointer pointing to this list of invalidated SDDbgNodes. As the memory gets reused, the list might get wrongly associated with another new SDNode. As the SDDbgValues are cloned when they are transfered, this can lead to an exponential number of SDDbgValues being produced during DAGCombine like in http://llvm.org/bugs/show_bug.cgi?id=20893 Note that the previous behavior wasn't really buggy as the invalidation made sure that the SDDbgValues won't be used. This commit can be considered a memory optimization and as such is really hard to validate in a unit-test.
50 lines
2.0 KiB
Plaintext
50 lines
2.0 KiB
Plaintext
$OpenBSD: patch-lib_CodeGen_SelectionDAG_SelectionDAG_cpp,v 1.1 2014/11/15 03:26:40 brad Exp $
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r221709
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Totally forget deallocated SDNodes in SDDbgInfo.
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What would happen before that commit is that the SDDbgValues associated with
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a deallocated SDNode would be marked Invalidated, but SDDbgInfo would keep
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a map entry keyed by the SDNode pointer pointing to this list of invalidated
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SDDbgNodes. As the memory gets reused, the list might get wrongly associated
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with another new SDNode. As the SDDbgValues are cloned when they are transfered,
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this can lead to an exponential number of SDDbgValues being produced during
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DAGCombine like in http://llvm.org/bugs/show_bug.cgi?id=20893
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Note that the previous behavior wasn't really buggy as the invalidation made
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sure that the SDDbgValues won't be used. This commit can be considered a
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memory optimization and as such is really hard to validate in a unit-test.
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--- lib/CodeGen/SelectionDAG/SelectionDAG.cpp.orig Fri Nov 14 21:02:43 2014
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+++ lib/CodeGen/SelectionDAG/SelectionDAG.cpp Fri Nov 14 21:08:05 2014
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@@ -642,6 +642,15 @@ void SelectionDAG::DeleteNodeNotInCSEMaps(SDNode *N) {
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DeallocateNode(N);
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}
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+void SDDbgInfo::erase(const SDNode *Node) {
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+ DbgValMapType::iterator I = DbgValMap.find(Node);
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+ if (I == DbgValMap.end())
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+ return;
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+ for (unsigned J = 0, N = I->second.size(); J != N; ++J)
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+ I->second[J]->setIsInvalidated();
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+ DbgValMap.erase(I);
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+}
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+
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void SelectionDAG::DeallocateNode(SDNode *N) {
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if (N->OperandsNeedDelete)
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delete[] N->OperandList;
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@@ -652,10 +661,9 @@ void SelectionDAG::DeallocateNode(SDNode *N) {
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NodeAllocator.Deallocate(AllNodes.remove(N));
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- // If any of the SDDbgValue nodes refer to this SDNode, invalidate them.
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- ArrayRef<SDDbgValue*> DbgVals = DbgInfo->getSDDbgValues(N);
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- for (unsigned i = 0, e = DbgVals.size(); i != e; ++i)
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- DbgVals[i]->setIsInvalidated();
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+ // If any of the SDDbgValue nodes refer to this SDNode, invalidate
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+ // them and forget about that node.
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+ DbgInfo->erase(N);
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}
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/// RemoveNodeFromCSEMaps - Take the specified node out of the CSE map that
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