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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
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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221709 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Frederic Riss 2014-11-11 21:21:08 +00:00
parent 63dea2c952
commit 6eb7964b7d
2 changed files with 16 additions and 4 deletions
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4
include/llvm/CodeGen/SelectionDAG.h
View File

@ -128,6 +128,10 @@ public:
DbgValMap[Node].push_back(V);
}
/// \brief Invalidate all DbgValues attached to the node and remove
/// it from the Node-to-DbgValues map.
void erase(const SDNode *Node);
void clear() {
DbgValMap.clear();
DbgValues.clear();

16
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -687,6 +687,15 @@ void SelectionDAG::DeleteNodeNotInCSEMaps(SDNode *N) {
DeallocateNode(N);
}
void SDDbgInfo::erase(const SDNode *Node) {
DbgValMapType::iterator I = DbgValMap.find(Node);
if (I == DbgValMap.end())
return;
for (auto &Val: I->second)
Val->setIsInvalidated();
DbgValMap.erase(I);
}
void SelectionDAG::DeallocateNode(SDNode *N) {
if (N->OperandsNeedDelete)
delete[] N->OperandList;
@ -697,10 +706,9 @@ void SelectionDAG::DeallocateNode(SDNode *N) {
NodeAllocator.Deallocate(AllNodes.remove(N));
// If any of the SDDbgValue nodes refer to this SDNode, invalidate them.
ArrayRef<SDDbgValue*> DbgVals = DbgInfo->getSDDbgValues(N);
for (unsigned i = 0, e = DbgVals.size(); i != e; ++i)
DbgVals[i]->setIsInvalidated();
// If any of the SDDbgValue nodes refer to this SDNode, invalidate
// them and forget about that node.
DbgInfo->erase(N);
}
#ifndef NDEBUG