When XDEBUG is enabled, check for SelectionDAG cycles at some key
points. This will help us find future problems like the one
described in PR6019.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94019 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index ad0e862..67b6d5c 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5172,6 +5172,7 @@
// count of outstanding operands.
for (allnodes_iterator I = allnodes_begin(),E = allnodes_end(); I != E; ) {
SDNode *N = I++;
+ checkForCycles(N);
unsigned Degree = N->getNumOperands();
if (Degree == 0) {
// A node with no uses, add it to the result array immediately.
@@ -5191,6 +5192,7 @@
// such that by the time the end is reached all nodes will be sorted.
for (allnodes_iterator I = allnodes_begin(),E = allnodes_end(); I != E; ++I) {
SDNode *N = I;
+ checkForCycles(N);
// N is in sorted position, so all its uses have one less operand
// that needs to be sorted.
for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
@@ -5216,7 +5218,7 @@
SDNode *S = ++J;
dbgs() << "Offending node:\n";
S->dumprFull();
- assert(I != SortedPos && "Overran sorted position");
+ assert(0 && "Overran sorted position");
}
}
@@ -6279,3 +6281,35 @@
return false;
return true;
}
+
+static void checkForCyclesHelper(const SDNode *N,
+ std::set<const SDNode *> &visited) {
+ if (visited.find(N) != visited.end()) {
+ dbgs() << "Offending node:\n";
+ N->dumprFull();
+ assert(0 && "Detected cycle in SelectionDAG");
+ }
+
+ std::set<const SDNode*>::iterator i;
+ bool inserted;
+
+ tie(i, inserted) = visited.insert(N);
+ assert(inserted && "Missed cycle");
+
+ for(unsigned i = 0; i < N->getNumOperands(); ++i) {
+ checkForCyclesHelper(N->getOperand(i).getNode(), visited);
+ }
+ visited.erase(i);
+}
+
+void llvm::checkForCycles(const llvm::SDNode *N) {
+#ifdef XDEBUG
+ assert(N && "Checking nonexistant SDNode");
+ std::set<const SDNode *> visited;
+ checkForCyclesHelper(N, visited);
+#endif
+}
+
+void llvm::checkForCycles(const llvm::SelectionDAG *DAG) {
+ checkForCycles(DAG->getRoot().getNode());
+}