Simplify UninitializedValues.cpp by removing logic to handle the previous (imprecise) representation
of '&&' and '||' in the CFG.  This is no longer needed, and greatly simplifies the code.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160494 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/UninitializedValues.cpp b/lib/Analysis/UninitializedValues.cpp
index acf695a..858be45 100644
--- a/lib/Analysis/UninitializedValues.cpp
+++ b/lib/Analysis/UninitializedValues.cpp
@@ -98,38 +98,32 @@
 namespace {
 
 typedef llvm::PackedVector<Value, 2> ValueVector;
-typedef std::pair<ValueVector *, ValueVector *> BVPair;
 
 class CFGBlockValues {
   const CFG &cfg;
-  BVPair *vals;
+  std::vector<ValueVector*> vals;
   ValueVector scratch;
   DeclToIndex declToIndex;
-  
-  ValueVector &lazyCreate(ValueVector *&bv);
 public:
   CFGBlockValues(const CFG &cfg);
   ~CFGBlockValues();
-  
+
   unsigned getNumEntries() const { return declToIndex.size(); }
   
   void computeSetOfDeclarations(const DeclContext &dc);  
-  ValueVector &getValueVector(const CFGBlock *block,
-                              const CFGBlock *dstBlock);
-
-  BVPair &getValueVectors(const CFGBlock *block, bool shouldLazyCreate);
+  ValueVector &getValueVector(const CFGBlock *block) {
+    return *vals[block->getBlockID()];
+  }
 
   void setAllScratchValues(Value V);
   void mergeIntoScratch(ValueVector const &source, bool isFirst);
   bool updateValueVectorWithScratch(const CFGBlock *block);
-  bool updateValueVectors(const CFGBlock *block, const BVPair &newVals);
   
   bool hasNoDeclarations() const {
     return declToIndex.size() == 0;
   }
 
   void resetScratch();
-  ValueVector &getScratch() { return scratch; }
   
   ValueVector::reference operator[](const VarDecl *vd);
 
@@ -137,91 +131,29 @@
                  const VarDecl *vd) {
     const llvm::Optional<unsigned> &idx = declToIndex.getValueIndex(vd);
     assert(idx.hasValue());
-    return getValueVector(block, dstBlock)[idx.getValue()];
+    return getValueVector(block)[idx.getValue()];
   }
 };  
 } // end anonymous namespace
 
-CFGBlockValues::CFGBlockValues(const CFG &c) : cfg(c), vals(0) {
-  unsigned n = cfg.getNumBlockIDs();
-  if (!n)
-    return;
-  vals = new std::pair<ValueVector*, ValueVector*>[n];
-  memset((void*)vals, 0, sizeof(*vals) * n);
-}
+CFGBlockValues::CFGBlockValues(const CFG &c) : cfg(c), vals(0) {}
 
 CFGBlockValues::~CFGBlockValues() {
-  unsigned n = cfg.getNumBlockIDs();
-  if (n == 0)
-    return;
-  for (unsigned i = 0; i < n; ++i) {
-    delete vals[i].first;
-    delete vals[i].second;
-  }
-  delete [] vals;
+  for (std::vector<ValueVector*>::iterator I = vals.begin(), E = vals.end();
+       I != E; ++I)
+    delete *I;
 }
 
 void CFGBlockValues::computeSetOfDeclarations(const DeclContext &dc) {
   declToIndex.computeMap(dc);
-  scratch.resize(declToIndex.size());
-}
-
-ValueVector &CFGBlockValues::lazyCreate(ValueVector *&bv) {
-  if (!bv)
-    bv = new ValueVector(declToIndex.size());
-  return *bv;
-}
-
-/// This function pattern matches for a '&&' or '||' that appears at
-/// the beginning of a CFGBlock that also (1) has a terminator and 
-/// (2) has no other elements.  If such an expression is found, it is returned.
-static const BinaryOperator *getLogicalOperatorInChain(const CFGBlock *block) {
-  if (block->empty())
-    return 0;
-
-  CFGElement front = block->front();
-  const CFGStmt *cstmt = front.getAs<CFGStmt>();
-  if (!cstmt)
-    return 0;
-
-  const BinaryOperator *b = dyn_cast_or_null<BinaryOperator>(cstmt->getStmt());
-  
-  if (!b || !b->isLogicalOp())
-    return 0;
-  
-  if (block->pred_size() == 2) {
-    if (block->getTerminatorCondition() == b) {
-      if (block->succ_size() == 2)
-      return b;
-    }
-    else if (block->size() == 1)
-      return b;
-  }
-
-  return 0;
-}
-
-ValueVector &CFGBlockValues::getValueVector(const CFGBlock *block,
-                                            const CFGBlock *dstBlock) {
-  unsigned idx = block->getBlockID();
-  if (dstBlock && getLogicalOperatorInChain(block)) {
-    if (*block->succ_begin() == dstBlock)
-      return lazyCreate(vals[idx].first);
-    assert(*(block->succ_begin()+1) == dstBlock);
-    return lazyCreate(vals[idx].second);
-  }
-
-  assert(vals[idx].second == 0);
-  return lazyCreate(vals[idx].first);
-}
-
-BVPair &CFGBlockValues::getValueVectors(const clang::CFGBlock *block,
-                                        bool shouldLazyCreate) {
-  unsigned idx = block->getBlockID();
-  lazyCreate(vals[idx].first);
-  if (shouldLazyCreate)
-    lazyCreate(vals[idx].second);
-  return vals[idx];
+  unsigned decls = declToIndex.size();
+  scratch.resize(decls);
+  unsigned n = cfg.getNumBlockIDs();
+  if (!n)
+    return;
+  vals.resize(n);
+  for (unsigned i = 0; i < n; ++i)
+    vals[i] = new ValueVector(decls);
 }
 
 #if DEBUG_LOGGING
@@ -249,7 +181,7 @@
 }
 
 bool CFGBlockValues::updateValueVectorWithScratch(const CFGBlock *block) {
-  ValueVector &dst = getValueVector(block, 0);
+  ValueVector &dst = getValueVector(block);
   bool changed = (dst != scratch);
   if (changed)
     dst = scratch;
@@ -259,20 +191,6 @@
   return changed;
 }
 
-bool CFGBlockValues::updateValueVectors(const CFGBlock *block,
-                                      const BVPair &newVals) {
-  BVPair &vals = getValueVectors(block, true);
-  bool changed = *newVals.first != *vals.first ||
-                 *newVals.second != *vals.second;
-  *vals.first = *newVals.first;
-  *vals.second = *newVals.second;
-#if DEBUG_LOGGING
-  printVector(block, *vals.first, 1);
-  printVector(block, *vals.second, 2);
-#endif
-  return changed;
-}
-
 void CFGBlockValues::resetScratch() {
   scratch.reset();
 }
@@ -768,42 +686,15 @@
                        const ClassifyRefs &classification,
                        llvm::BitVector &wasAnalyzed,
                        UninitVariablesHandler *handler = 0) {
-  
   wasAnalyzed[block->getBlockID()] = true;
-  
-  if (const BinaryOperator *b = getLogicalOperatorInChain(block)) {
-    CFGBlock::const_pred_iterator itr = block->pred_begin();
-    BVPair vA = vals.getValueVectors(*itr, false);
-    ++itr;
-    BVPair vB = vals.getValueVectors(*itr, false);
-
-    BVPair valsAB;
-    
-    if (b->getOpcode() == BO_LAnd) {
-      // Merge the 'F' bits from the first and second.
-      vals.mergeIntoScratch(*(vA.second ? vA.second : vA.first), true);
-      vals.mergeIntoScratch(*(vB.second ? vB.second : vB.first), false);
-      valsAB.first = vA.first;
-      valsAB.second = &vals.getScratch();
-    } else {
-      // Merge the 'T' bits from the first and second.
-      assert(b->getOpcode() == BO_LOr);
-      vals.mergeIntoScratch(*vA.first, true);
-      vals.mergeIntoScratch(*vB.first, false);
-      valsAB.first = &vals.getScratch();
-      valsAB.second = vA.second ? vA.second : vA.first;
-    }
-    return vals.updateValueVectors(block, valsAB);
-  }
-
-  // Default behavior: merge in values of predecessor blocks.
   vals.resetScratch();
+  // Merge in values of predecessor blocks.
   bool isFirst = true;
   for (CFGBlock::const_pred_iterator I = block->pred_begin(),
        E = block->pred_end(); I != E; ++I) {
     const CFGBlock *pred = *I;
     if (wasAnalyzed[pred->getBlockID()]) {
-      vals.mergeIntoScratch(vals.getValueVector(pred, block), isFirst);
+      vals.mergeIntoScratch(vals.getValueVector(pred), isFirst);
       isFirst = false;
     }
   }
@@ -828,9 +719,6 @@
   vals.computeSetOfDeclarations(dc);
   if (vals.hasNoDeclarations())
     return;
-#if DEBUG_LOGGING
-  cfg.dump(dc.getParentASTContext().getLangOpts(), true);
-#endif
 
   stats.NumVariablesAnalyzed = vals.getNumEntries();
 
@@ -840,15 +728,10 @@
 
   // Mark all variables uninitialized at the entry.
   const CFGBlock &entry = cfg.getEntry();
-  for (CFGBlock::const_succ_iterator i = entry.succ_begin(), 
-        e = entry.succ_end(); i != e; ++i) {
-    if (const CFGBlock *succ = *i) {
-      ValueVector &vec = vals.getValueVector(&entry, succ);
-      const unsigned n = vals.getNumEntries();
-      for (unsigned j = 0; j < n ; ++j) {
-        vec[j] = Uninitialized;
-      }
-    }
+  ValueVector &vec = vals.getValueVector(&entry);
+  const unsigned n = vals.getNumEntries();
+  for (unsigned j = 0; j < n ; ++j) {
+    vec[j] = Uninitialized;
   }
 
   // Proceed with the workist.