+/// \\brief A DAG update listener to keep the matching state
+/// (i.e. RecordedNodes and MatchScope) uptodate if the target is allowed to
+/// change the DAG while matching. X86 addressing mode matcher is an example
+/// for this.
+class MatchStateUpdater : public SelectionDAG::DAGUpdateListener
+{
+ SmallVectorImpl<std::pair<SDValue, SDNode*> > &RecordedNodes;
+ SmallVectorImpl<MatchScope> &MatchScopes;
+public:
+ MatchStateUpdater(SelectionDAG &DAG,
+ SmallVectorImpl<std::pair<SDValue, SDNode*> > &RN,
+ SmallVectorImpl<MatchScope> &MS) :
+ SelectionDAG::DAGUpdateListener(DAG),
+ RecordedNodes(RN), MatchScopes(MS) { }
+
+ void NodeDeleted(SDNode *N, SDNode *E) {
+ // Some early-returns here to avoid the search if we deleted the node or
+ // if the update comes from MorphNodeTo (MorphNodeTo is the last thing we
+ // do, so it's unnecessary to update matching state at that point).
+ // Neither of these can occur currently because we only install this
+ // update listener during matching a complex patterns.
+ if (!E || E->isMachineOpcode())
+ return;
+ // Performing linear search here does not matter because we almost never
+ // run this code. You'd have to have a CSE during complex pattern
+ // matching.
+ for (auto &I : RecordedNodes)
+ if (I.first.getNode() == N)
+ I.first.setNode(E);
+
+ for (auto &I : MatchScopes)
+ for (auto &J : I.NodeStack)
+ if (J.getNode() == N)
+ J.setNode(E);
+ }
+};