[SelectionDAG] Force cycle detection in AssignTopologicalOrder before aborting
DAG cycle detection is only enabled with ENABLE_EXPENSIVE_CHECKS. However we
can run it just before we would crash in order to provide more informative
diagnostics.
Now in addition to the "Overran sorted position" message we also get the Node
printed if a cycle was detected.
Tested by building several configs: Debug+Assert, Debug+Assert+Check (this is
ENABLE_EXPENSIVE_CHECKS), Release+Assert and Release. Also tried that the
AssignTopologicalOrder assert produces the expected results.
llvm-svn: 209977
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 0f1d975..b701add 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -6002,6 +6002,8 @@
SDNode *S = ++I;
dbgs() << "Overran sorted position:\n";
S->dumprFull(this); dbgs() << "\n";
+ dbgs() << "Checking if this is due to cycles\n";
+ checkForCycles(this, true);
#endif
llvm_unreachable(nullptr);
}
@@ -6587,7 +6589,7 @@
return true;
}
-#ifdef XDEBUG
+#ifndef NDEBUG
static void checkForCyclesHelper(const SDNode *N,
SmallPtrSet<const SDNode*, 32> &Visited,
SmallPtrSet<const SDNode*, 32> &Checked,
@@ -6614,15 +6616,22 @@
#endif
void llvm::checkForCycles(const llvm::SDNode *N,
- const llvm::SelectionDAG *DAG) {
+ const llvm::SelectionDAG *DAG,
+ bool force) {
+#ifndef NDEBUG
+ bool check = force;
#ifdef XDEBUG
- assert(N && "Checking nonexistent SDNode");
- SmallPtrSet<const SDNode*, 32> visited;
- SmallPtrSet<const SDNode*, 32> checked;
- checkForCyclesHelper(N, visited, checked, DAG);
-#endif
+ check = true;
+#endif // XDEBUG
+ if (check) {
+ assert(N && "Checking nonexistent SDNode");
+ SmallPtrSet<const SDNode*, 32> visited;
+ SmallPtrSet<const SDNode*, 32> checked;
+ checkForCyclesHelper(N, visited, checked, DAG);
+ }
+#endif // !NDEBUG
}
-void llvm::checkForCycles(const llvm::SelectionDAG *DAG) {
- checkForCycles(DAG->getRoot().getNode(), DAG);
+void llvm::checkForCycles(const llvm::SelectionDAG *DAG, bool force) {
+ checkForCycles(DAG->getRoot().getNode(), DAG, force);
}