Revert patches to add case-range support for PR1255.

The work on this project was left in an unfinished and inconsistent state.
Hopefully someone will eventually get a chance to implement this feature, but
in the meantime, it is better to put things back the way the were.  I have
left support in the bitcode reader to handle the case-range bitcode format,
so that we do not lose bitcode compatibility with the llvm 3.3 release.

This reverts the following commits: 155464, 156374, 156377, 156613, 156704,
156757, 156804 156808, 156985, 157046, 157112, 157183, 157315, 157384, 157575,
157576, 157586, 157612, 157810, 157814, 157815, 157880, 157881, 157882, 157884,
157887, 157901, 158979, 157987, 157989, 158986, 158997, 159076, 159101, 159100,
159200, 159201, 159207, 159527, 159532, 159540, 159583, 159618, 159658, 159659,
159660, 159661, 159703, 159704, 160076, 167356, 172025, 186736

llvm-svn: 190328

2 files changed, 53 insertions, 36 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 086313b7334..0971e8a926d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -49,7 +49,6 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/IntegersSubsetMapping.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetFrameLowering.h"
@@ -1618,8 +1617,7 @@ void SelectionDAGBuilder::visitSwitchCase(CaseBlock &CB,
     } else
       Cond = DAG.getSetCC(dl, MVT::i1, CondLHS, getValue(CB.CmpRHS), CB.CC);
   } else {
-    assert(CB.CC == ISD::SETCC_INVALID &&
-           "Condition is undefined for to-the-range belonging check.");
+    assert(CB.CC == ISD::SETLE && "Can handle only LE ranges now");
 
     const APInt& Low = cast<ConstantInt>(CB.CmpLHS)->getValue();
     const APInt& High  = cast<ConstantInt>(CB.CmpRHS)->getValue();
@@ -1627,9 +1625,9 @@ void SelectionDAGBuilder::visitSwitchCase(CaseBlock &CB,
     SDValue CmpOp = getValue(CB.CmpMHS);
     EVT VT = CmpOp.getValueType();
 
-    if (cast<ConstantInt>(CB.CmpLHS)->isMinValue(false)) {
+    if (cast<ConstantInt>(CB.CmpLHS)->isMinValue(true)) {
       Cond = DAG.getSetCC(dl, MVT::i1, CmpOp, DAG.getConstant(High, VT),
-                          ISD::SETULE);
+                          ISD::SETLE);
     } else {
       SDValue SUB = DAG.getNode(ISD::SUB, dl,
                                 VT, CmpOp, DAG.getConstant(Low, VT));
@@ -2145,7 +2143,7 @@ bool SelectionDAGBuilder::handleSmallSwitchRange(CaseRec& CR,
       CC = ISD::SETEQ;
       LHS = SV; RHS = I->High; MHS = NULL;
     } else {
-      CC = ISD::SETCC_INVALID;
+      CC = ISD::SETLE;
       LHS = I->Low; MHS = SV; RHS = I->High;
     }
 
@@ -2179,7 +2177,7 @@ static inline bool areJTsAllowed(const TargetLowering &TLI) {
 
 static APInt ComputeRange(const APInt &First, const APInt &Last) {
   uint32_t BitWidth = std::max(Last.getBitWidth(), First.getBitWidth()) + 1;
-  APInt LastExt = Last.zext(BitWidth), FirstExt = First.zext(BitWidth);
+  APInt LastExt = Last.sext(BitWidth), FirstExt = First.sext(BitWidth);
   return (LastExt - FirstExt + 1ULL);
 }
 
@@ -2246,7 +2244,7 @@ bool SelectionDAGBuilder::handleJTSwitchCase(CaseRec &CR,
     const APInt &Low = cast<ConstantInt>(I->Low)->getValue();
     const APInt &High = cast<ConstantInt>(I->High)->getValue();
 
-    if (Low.ule(TEI) && TEI.ule(High)) {
+    if (Low.sle(TEI) && TEI.sle(High)) {
       DestBBs.push_back(I->BB);
       if (TEI==High)
         ++I;
@@ -2420,7 +2418,7 @@ bool SelectionDAGBuilder::handleBTSplitSwitchCase(CaseRec& CR,
   // Create a CaseBlock record representing a conditional branch to
   // the LHS node if the value being switched on SV is less than C.
   // Otherwise, branch to LHS.
-  CaseBlock CB(ISD::SETULT, SV, C, NULL, TrueBB, FalseBB, CR.CaseBB);
+  CaseBlock CB(ISD::SETLT, SV, C, NULL, TrueBB, FalseBB, CR.CaseBB);
 
   if (CR.CaseBB == SwitchBB)
     visitSwitchCase(CB, SwitchBB);
@@ -2493,7 +2491,7 @@ bool SelectionDAGBuilder::handleBitTestsSwitchCase(CaseRec& CR,
   // Optimize the case where all the case values fit in a
   // word without having to subtract minValue. In this case,
   // we can optimize away the subtraction.
-  if (maxValue.ult(IntPtrBits)) {
+  if (minValue.isNonNegative() && maxValue.slt(IntPtrBits)) {
     cmpRange = maxValue;
   } else {
     lowBound = minValue;
@@ -2568,12 +2566,7 @@ bool SelectionDAGBuilder::handleBitTestsSwitchCase(CaseRec& CR,
 /// Clusterify - Transform simple list of Cases into list of CaseRange's
 size_t SelectionDAGBuilder::Clusterify(CaseVector& Cases,
                                        const SwitchInst& SI) {
-
-  /// Use a shorter form of declaration, and also
-  /// show the we want to use CRSBuilder as Clusterifier.
-  typedef IntegersSubsetMapping<MachineBasicBlock> Clusterifier;
-
-  Clusterifier TheClusterifier;
+  size_t numCmps = 0;
 
   BranchProbabilityInfo *BPI = FuncInfo.BPI;
   // Start with "simple" cases
@@ -2582,27 +2575,40 @@ size_t SelectionDAGBuilder::Clusterify(CaseVector& Cases,
     const BasicBlock *SuccBB = i.getCaseSuccessor();
     MachineBasicBlock *SMBB = FuncInfo.MBBMap[SuccBB];
 
-    TheClusterifier.add(i.getCaseValueEx(), SMBB,
-        BPI ? BPI->getEdgeWeight(SI.getParent(), i.getSuccessorIndex()) : 0);
-  }
-
-  TheClusterifier.optimize();
+    uint32_t ExtraWeight =
+      BPI ? BPI->getEdgeWeight(SI.getParent(), i.getSuccessorIndex()) : 0;
+
+    Cases.push_back(Case(i.getCaseValue(), i.getCaseValue(),
+                         SMBB, ExtraWeight));
+  }
+  std::sort(Cases.begin(), Cases.end(), CaseCmp());
+
+  // Merge case into clusters
+  if (Cases.size() >= 2)
+    // Must recompute end() each iteration because it may be
+    // invalidated by erase if we hold on to it
+    for (CaseItr I = Cases.begin(), J = llvm::next(Cases.begin());
+         J != Cases.end(); ) {
+      const APInt& nextValue = cast<ConstantInt>(J->Low)->getValue();
+      const APInt& currentValue = cast<ConstantInt>(I->High)->getValue();
+      MachineBasicBlock* nextBB = J->BB;
+      MachineBasicBlock* 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;
+        I->ExtraWeight += J->ExtraWeight;
+        J = Cases.erase(J);
+      } else {
+        I = J++;
+      }
+    }
 
-  size_t numCmps = 0;
-  for (Clusterifier::RangeIterator i = TheClusterifier.begin(),
-       e = TheClusterifier.end(); i != e; ++i, ++numCmps) {
-    Clusterifier::Cluster &C = *i;
-    // Update edge weight for the cluster.
-    unsigned W = C.first.Weight;
-
-    // FIXME: Currently work with ConstantInt based numbers.
-    // Changing it to APInt based is a pretty heavy for this commit.
-    Cases.push_back(Case(C.first.getLow().toConstantInt(),
-                         C.first.getHigh().toConstantInt(), C.second, W));
-
-    if (C.first.getLow() != C.first.getHigh())
-    // A range counts double, since it requires two compares.
-    ++numCmps;
+  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;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index e995424527d..6463ecaca5a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -182,6 +182,17 @@ private:
 
   typedef std::vector<CaseRec> CaseRecVector;
 
+  /// The comparison function for sorting the switch case values in the vector.
+  /// WARNING: Case ranges should be disjoint!
+  struct CaseCmp {
+    bool operator()(const Case &C1, const Case &C2) {
+      assert(isa<ConstantInt>(C1.Low) && isa<ConstantInt>(C2.High));
+      const ConstantInt* CI1 = cast<const ConstantInt>(C1.Low);
+      const ConstantInt* CI2 = cast<const ConstantInt>(C2.High);
+      return CI1->getValue().slt(CI2->getValue());
+    }
+  };
+
   struct CaseBitsCmp {
     bool operator()(const CaseBits &C1, const CaseBits &C2) {
       return C1.Bits > C2.Bits;