1 files changed, 34 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index f96fc208ae..1f3e6b11c8 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -407,6 +407,12 @@ bool JumpThreading::ProcessBranchOnDuplicateCond(BasicBlock *PredBB,
   return true;
 }
 
+struct APIntUnsignedOrdering {
+  bool operator()(const APInt &LHS, const APInt &RHS) const {
+    return LHS.ult(RHS);
+  }
+};
+
 /// ProcessSwitchOnDuplicateCond - We found a block and a predecessor of that
 /// block that switch on exactly the same condition.  This means that we almost
 /// always know the direction of the edge in the DESTBB:
@@ -474,6 +480,34 @@ bool JumpThreading::ProcessSwitchOnDuplicateCond(BasicBlock *PredBB,
       return true;
   }
   
+#if 0
+  // Figure out on which of the condition allow us to get to DESTBB.  If DESTBB
+  // is the default label, we compute the set of values COND is known not to be
+  // otherwise we compute the set of options that COND could be.
+  SmallVector<APInt, 16> KnownValues;
+  bool DestBBIsDefault = PredSI->getSuccessor(0) == DestBB;
+  
+  if (DestBBIsDefault) {
+    // DestBB the default case.  Collect the values where PredBB can't branch to
+    // DestBB.
+    for (unsigned i = 1/*skip default*/, e = PredSI->getNumCases(); i != e; ++i)
+      if (PredSI->getSuccessor(i) != DestBB)
+        KnownValues.push_back(PredSI->getCaseValue(i)->getValue());
+  } else {
+    // Not the default case.  Collect the values where PredBB can branch to
+    // DestBB.
+    for (unsigned i = 1/*skip default*/, e = PredSI->getNumCases(); i != e; ++i)
+      if (PredSI->getSuccessor(i) == DestBB)
+        KnownValues.push_back(PredSI->getCaseValue(i)->getValue());
+  }
+  
+  std::sort(KnownValues.begin(), KnownValues.end(), APIntUnsignedOrdering());
+  return false;
+  cerr << "\nFOUND THREAD BLOCKS:\n";
+  PredBB->dump();
+  DestBB->dump();
+#endif
+  
   return false;
 }