From 1908ff46dae3aaf4aa454b841982f2204ad19621 Mon Sep 17 00:00:00 2001
From: David Greene <greened@obbligato.org>
Date: Wed, 20 Jan 2010 00:59:23 +0000
Subject: [PATCH] Add some asserts to check SelectionDAG problems earlier.

llvm-svn: 93960
---
 lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 49b08bba790..ad0e862c6b9 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5179,6 +5179,7 @@ unsigned SelectionDAG::AssignTopologicalOrder() {
       allnodes_iterator Q = N;
       if (Q != SortedPos)
         SortedPos = AllNodes.insert(SortedPos, AllNodes.remove(Q));
+      assert(SortedPos != AllNodes.end() && "Overran node list");
       ++SortedPos;
     } else {
       // Temporarily use the Node Id as scratch space for the degree count.
@@ -5190,22 +5191,33 @@ 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;
+    // 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();
          UI != UE; ++UI) {
       SDNode *P = *UI;
       unsigned Degree = P->getNodeId();
+      assert(Degree != 0 && "Invalid node degree");
       --Degree;
       if (Degree == 0) {
         // All of P's operands are sorted, so P may sorted now.
         P->setNodeId(DAGSize++);
         if (P != SortedPos)
           SortedPos = AllNodes.insert(SortedPos, AllNodes.remove(P));
+        assert(SortedPos != AllNodes.end() && "Overran node list");
         ++SortedPos;
       } else {
         // Update P's outstanding operand count.
         P->setNodeId(Degree);
       }
     }
+    if (I == SortedPos) {
+      allnodes_iterator J = I;
+      SDNode *S = ++J;
+      dbgs() << "Offending node:\n";
+      S->dumprFull();
+      assert(I != SortedPos && "Overran sorted position");
+    }
   }
 
   assert(SortedPos == AllNodes.end() &&