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When XDEBUG is enabled, check for SelectionDAG cycles at some key

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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
This commit is contained in:
David Greene
2010-01-20 20:13:31 +00:00
parent 1bc76d48d4
commit cf495bc2e5
4 changed files with 54 additions and 2 deletions
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36
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -5172,6 +5172,7 @@ unsigned SelectionDAG::AssignTopologicalOrder() {
// 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 @@ unsigned SelectionDAG::AssignTopologicalOrder() {
// 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 @@ unsigned SelectionDAG::AssignTopologicalOrder() {
SDNode *S = ++J;
dbgs() << "Offending node:\n";
S->dumprFull();
assert(I != SortedPos && "Overran sorted position");
assert(0 && "Overran sorted position");
}
}
@ -6279,3 +6281,35 @@ bool ShuffleVectorSDNode::isSplatMask(const int *Mask, EVT VT) {
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());
}