From f0f42687c6a549ea49f9c4f3493390f1da691726 Mon Sep 17 00:00:00 2001
From: Stepan Dyatkovskiy <stpworld@narod.ru>
Date: Tue, 15 May 2012 06:50:18 +0000
Subject: [PATCH] Rejected r156804 due to buildbots failures.

llvm-svn: 156808
---
 .../SelectionDAG/SelectionDAGBuilder.cpp      | 79 +++++++++++--------
 1 file changed, 45 insertions(+), 34 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 937fe547e6a..4f45e76456f 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -51,7 +51,6 @@
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CommandLine.h"
-#include "llvm/Support/CRSBuilder.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
@@ -2039,7 +2038,7 @@ 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);
 }
 
@@ -2105,7 +2104,7 @@ 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;
@@ -2184,10 +2183,8 @@ bool SelectionDAGBuilder::handleBTSplitSwitchCase(CaseRec& CR,
     const APInt &LEnd = cast<ConstantInt>(I->High)->getValue();
     const APInt &RBegin = cast<ConstantInt>(J->Low)->getValue();
     APInt Range = ComputeRange(LEnd, RBegin);
-    // Old: assert((Range - 2ULL).isNonNegative() && "Invalid case distance");
-    // Why APInt::sge wasn't used? 
-    assert(Range.uge(APInt(Range.getBitWidth(), 2)) && "Invalid case distance");
-    
+    assert((Range - 2ULL).isNonNegative() &&
+           "Invalid case distance");
     // Use volatile double here to avoid excess precision issues on some hosts,
     // e.g. that use 80-bit X87 registers.
     volatile double LDensity =
@@ -2410,43 +2407,57 @@ 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 CRSBuilderBase<MachineBasicBlock, true> Clusterifier;
-  
-  Clusterifier TheClusterifier;
+  size_t numCmps = 0;
 
+  BranchProbabilityInfo *BPI = FuncInfo.BPI;
   // Start with "simple" cases
   for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
        i != e; ++i) {
     const BasicBlock *SuccBB = i.getCaseSuccessor();
     MachineBasicBlock *SMBB = FuncInfo.MBBMap[SuccBB];
 
-    TheClusterifier.add(i.getCaseValueEx(), SMBB);
+    uint32_t ExtraWeight = BPI ? BPI->getEdgeWeight(SI.getParent(), SuccBB) : 0;
+
+    Cases.push_back(Case(i.getCaseValue(), i.getCaseValue(),
+                         SMBB, ExtraWeight));
   }
-  
-  TheClusterifier.optimize();
-  
-  BranchProbabilityInfo *BPI = FuncInfo.BPI;
-  size_t numCmps = 0;
-  for (Clusterifier::RangeIterator i = TheClusterifier.begin(),
-       e = TheClusterifier.end(); i != e; ++i, ++numCmps) {
-    Clusterifier::Cluster &C = *i;
-    unsigned W = 0;
-    if (BPI) {
-      W = BPI->getEdgeWeight(SI.getParent(), C.second->getBasicBlock());
-      if (!W)
-        W = 16;
-      W *= C.first.Weight;
-      BPI->setEdgeWeight(SI.getParent(), C.second->getBasicBlock(), W);  
+  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;
+        J = Cases.erase(J);
+
+        if (BranchProbabilityInfo *BPI = FuncInfo.BPI) {
+          uint32_t CurWeight = currentBB->getBasicBlock() ?
+            BPI->getEdgeWeight(SI.getParent(), currentBB->getBasicBlock()) : 16;
+          uint32_t NextWeight = nextBB->getBasicBlock() ?
+            BPI->getEdgeWeight(SI.getParent(), nextBB->getBasicBlock()) : 16;
+
+          BPI->setEdgeWeight(SI.getParent(), currentBB->getBasicBlock(),
+                             CurWeight + NextWeight);
+        }
+      } else {
+        I = J++;
+      }
     }
 
-    Cases.push_back(Case(C.first.Low, C.first.High, C.second, W));
-    
-    if (C.first.Low != C.first.High)
-    // 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;