1 files changed, 40 insertions, 22 deletions

diff --git a/lib/Transforms/Utils/LowerSwitch.cpp b/lib/Transforms/Utils/LowerSwitch.cpp
index 955b853..2d2a8a5 100644
--- a/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/lib/Transforms/Utils/LowerSwitch.cpp
@@ -66,6 +66,18 @@ namespace {
                              BasicBlock* OrigBlock, BasicBlock* Default);
     unsigned Clusterify(CaseVector& Cases, SwitchInst *SI);
   };
+
+  /// The comparison function for sorting the switch case values in the vector.
+  /// WARNING: Case ranges should be disjoint!
+  struct CaseCmp {
+    bool operator () (const LowerSwitch::CaseRange& C1,
+                      const LowerSwitch::CaseRange& C2) {
+
+      const ConstantInt* CI1 = cast<const ConstantInt>(C1.Low);
+      const ConstantInt* CI2 = cast<const ConstantInt>(C2.High);
+      return CI1->getValue().slt(CI2->getValue());
+    }
+  };
 }
 
 char LowerSwitch::ID = 0;
@@ -147,7 +159,7 @@ BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End,
   Function::iterator FI = OrigBlock;
   F->getBasicBlockList().insert(++FI, NewNode);
 
-  ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_ULT,
+  ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_SLT,
                                 Val, Pivot.Low, "Pivot");
   NewNode->getInstList().push_back(Comp);
   BranchInst::Create(LBranch, RBranch, Comp, NewNode);
@@ -222,34 +234,40 @@ BasicBlock* LowerSwitch::newLeafBlock(CaseRange& Leaf, Value* Val,
 
 // Clusterify - Transform simple list of Cases into list of CaseRange's
 unsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) {
-
-  IntegersSubsetToBB TheClusterifier;
+  unsigned numCmps = 0;
 
   // Start with "simple" cases
-  for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
-       i != e; ++i) {
-    BasicBlock *SuccBB = i.getCaseSuccessor();
-    IntegersSubset CaseRanges = i.getCaseValueEx();
-    TheClusterifier.add(CaseRanges, SuccBB);
-  }
-  
-  TheClusterifier.optimize();
+  for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i)
+    Cases.push_back(CaseRange(i.getCaseValue(), i.getCaseValue(),
+                              i.getCaseSuccessor()));
   
-  size_t numCmps = 0;
-  for (IntegersSubsetToBB::RangeIterator i = TheClusterifier.begin(),
-       e = TheClusterifier.end(); i != e; ++i, ++numCmps) {
-    IntegersSubsetToBB::Cluster &C = *i;
-    
-    // FIXME: Currently work with ConstantInt based numbers.
-    // Changing it to APInt based is a pretty heavy for this commit.
-    Cases.push_back(CaseRange(C.first.getLow().toConstantInt(),
-                              C.first.getHigh().toConstantInt(), C.second));
-    if (C.first.isSingleNumber())
+  std::sort(Cases.begin(), Cases.end(), CaseCmp());
+
+  // Merge case into clusters
+  if (Cases.size()>=2)
+    for (CaseItr I=Cases.begin(), J=llvm::next(Cases.begin()); J!=Cases.end(); ) {
+      int64_t nextValue = cast<ConstantInt>(J->Low)->getSExtValue();
+      int64_t currentValue = cast<ConstantInt>(I->High)->getSExtValue();
+      BasicBlock* nextBB = J->BB;
+      BasicBlock* currentBB = I->BB;
+
+      // If the two neighboring cases go to the same destination, merge them
+      // into a single case.
+      if ((nextValue-currentValue==1) && (currentBB == nextBB)) {
+        I->High = J->High;
+        J = Cases.erase(J);
+      } else {
+        I = J++;
+      }
+    }
+
+  for (CaseItr I=Cases.begin(), E=Cases.end(); I!=E; ++I, ++numCmps) {
+    if (I->Low != I->High)
       // A range counts double, since it requires two compares.
       ++numCmps;
   }
 
-  return numCmps;  
+  return numCmps;
 }
 
 // processSwitchInst - Replace the specified switch instruction with a sequence