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[SDAG] Rather than using a narrow test against the one dummy node on the 

stack, filter all handle nodes from the DAG combiner worklist.

This will also handle cases where other handle nodes might be
(erroneously) added to the worklist and then cause bugs and explosions
when deleted. For example, when running the legalizer within the DAG
combiner, there are times when other handle nodes are used and can end
up here.

llvm-svn: 213505
This commit is contained in:
Chandler Carruth 2014-07-21 08:32:31 +00:00
parent 0fb2013192
commit 24ceb0ce66
1 changed files with 6 additions and 1 deletions
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7
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -127,6 +127,11 @@ namespace {
/// AddToWorkList - Add to the work list making sure its instance is at the
/// back (next to be processed.)
void AddToWorkList(SDNode *N) {
// Skip handle nodes as they can't usefully be combined and confuse the
// zero-use deletion strategy.
if (N->getOpcode() == ISD::HANDLENODE)
return;
WorkListContents.insert(N);
WorkListOrder.push_back(N);
}
@ -1108,7 +1113,7 @@ void DAGCombiner::Run(CombineLevel AtLevel) {
// If N has no uses, it is dead. Make sure to revisit all N's operands once
// N is deleted from the DAG, since they too may now be dead or may have a
// reduced number of uses, allowing other xforms.
if (N->use_empty() && N != &Dummy) {
if (N->use_empty()) {
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
AddToWorkList(N->getOperand(i).getNode());