Adding bounds inference of the form count(i+1) (#602)

* Adding bounds inferrence of the form count(i+1)

* Fixing Review comments

* Fixing issue where the declaration has only types

Author: Machiry

clang/include/clang/3C/ABounds.h

@@ -28,14 +28,16 @@ class ABounds {
     InvalidKind,
     // Bounds that represent number of items.
     CountBoundKind,
+    // Count bounds but plus one, i.e., count(i+1)
+    CountPlusOneBoundKind,
     // Bounds that represent number of bytes.
     ByteBoundKind,
     // Bounds that represent range.
     RangeBoundKind,
   };
   BoundsKind getKind() const { return Kind; }
 
-private:
+protected:
   BoundsKind Kind;
 
 protected:
@@ -83,10 +85,24 @@ class CountBound : public ABounds {
 
   BoundsKey getCountVar() { return CountVar; }
 
-private:
+protected:
   BoundsKey CountVar;
 };
 
+class CountPlusOneBound : public CountBound {
+public:
+  CountPlusOneBound(BoundsKey Var) : CountBound(Var) {
+    this->Kind = CountPlusOneBoundKind;
+  }
+
+  std::string mkString(AVarBoundsInfo *ABI, clang::Decl *D = nullptr) override;
+  bool areSame(ABounds *O, AVarBoundsInfo *ABI) override;
+
+  static bool classof(const ABounds *S) {
+    return S->getKind() == CountPlusOneBoundKind;
+  }
+};
+
 class ByteBound : public ABounds {
 public:
   ByteBound(BoundsKey Var) : ABounds(ByteBoundKind), ByteVar(Var) {

clang/include/clang/3C/AVarBoundsInfo.h

@@ -138,6 +138,8 @@ class AvarBoundsInference {
   bool hasImpossibleBounds(BoundsKey BK);
   // Set the given pointer to have impossible bounds.
   void setImpossibleBounds(BoundsKey BK);
+  // Infer bounds of the given pointer key from potential bounds.
+  bool inferFromPotentialBounds(BoundsKey BK, AVarGraph &BKGraph);
 
   AVarBoundsInfo *BI;
 
@@ -147,6 +149,31 @@ class AvarBoundsInference {
   std::set<BoundsKey> BKsFailedFlowInference;
 };
 
+// Class that maintains information about potential bounds for
+// various pointer variables.
+class PotentialBoundsInfo {
+public:
+  PotentialBoundsInfo() {
+    PotentialCntBounds.clear();
+    PotentialCntPOneBounds.clear();
+  }
+  // Count Bounds, i.e., count(i).
+  bool hasPotentialCountBounds(BoundsKey PtrBK);
+  std::set<BoundsKey> &getPotentialBounds(BoundsKey PtrBK);
+  void addPotentialBounds(BoundsKey BK, const std::set<BoundsKey> &PotK);
+
+  // Count Bounds Plus one, i.e., count(i+1).
+  bool hasPotentialCountPOneBounds(BoundsKey PtrBK);
+  std::set<BoundsKey> &getPotentialBoundsPOne(BoundsKey PtrBK);
+  void addPotentialBoundsPOne(BoundsKey BK, const std::set<BoundsKey> &PotK);
+private:
+  // This is the map of pointer variable bounds key and set of bounds key
+  // which can be the count bounds.
+  std::map<BoundsKey, std::set<BoundsKey>> PotentialCntBounds;
+  // Potential count + 1 bounds.
+  std::map<BoundsKey, std::set<BoundsKey>> PotentialCntPOneBounds;
+};
+
 class AVarBoundsInfo {
 public:
   AVarBoundsInfo() : ProgVarGraph(this), CtxSensProgVarGraph(this),
@@ -171,7 +198,10 @@ class AVarBoundsInfo {
   bool replaceBounds(BoundsKey L, BoundsPriority P, ABounds *B);
   ABounds *getBounds(BoundsKey L, BoundsPriority ReqP = Invalid,
                      BoundsPriority *RetP = nullptr);
-  bool updatePotentialCountBounds(BoundsKey BK, std::set<BoundsKey> &CntBK);
+  void updatePotentialCountBounds(BoundsKey BK,
+                                  const std::set<BoundsKey> &CntBK);
+  void updatePotentialCountPOneBounds(BoundsKey BK,
+                                      const std::set<BoundsKey> &CntBK);
 
   // Try and get BoundsKey, into R, for the given declaration. If the
   // declaration does not have a BoundsKey then return false.
@@ -316,9 +346,8 @@ class AVarBoundsInfo {
   AVarGraph RevCtxSensProgVarGraph;
   // Stats on techniques used to find length for various variables.
   AVarBoundsStats BoundsInferStats;
-  // This is the map of pointer variable bounds key and set of bounds key
-  // which can be the count bounds.
-  std::map<BoundsKey, std::set<BoundsKey>> PotentialCntBounds;
+  // Information about potential bounds.
+  PotentialBoundsInfo PotBoundsInfo;
   // Context-sensitive bounds key handler
   CtxSensitiveBoundsKeyHandler CSBKeyHandler;
 
@@ -351,7 +380,8 @@ class AVarBoundsInfo {
   // Perform worklist based inference on the requested array variables using
   // the provided graph and potential length variables.
   bool performWorkListInference(const std::set<BoundsKey> &ArrNeededBounds,
-                                AVarGraph &BKGraph, AvarBoundsInference &BI);
+                                AVarGraph &BKGraph, AvarBoundsInference &BI,
+                                bool FromPB);
 
   void insertParamKey(ParamDeclType ParamDecl, BoundsKey NK);
 };

clang/lib/3C/ABounds.cpp

@@ -72,6 +72,10 @@ std::string ABounds::getBoundsKeyStr(BoundsKey BK,
     if (FD->getNumParams() > PIdx) {
       auto *NewPVD = FD->getParamDecl(PIdx);
       BKStr = NewPVD->getNameAsString();
+      // If the parameter in the new declaration does not have a name?
+      // then use the old name.
+      if (BKStr.empty())
+        BKStr = PV->mkString();
     }
   }
   return BKStr;
@@ -93,16 +97,24 @@ BoundsKey CountBound::getBKey() { return this->CountVar; }
 
 ABounds *CountBound::makeCopy(BoundsKey NK) { return new CountBound(NK); }
 
+std::string CountPlusOneBound::mkString(AVarBoundsInfo *ABI, clang::Decl *D) {
+  std::string CVar = ABounds::getBoundsKeyStr(CountVar, ABI, D);
+  return "count(" + CVar + " + 1)";
+}
+
+bool CountPlusOneBound::areSame(ABounds *O, AVarBoundsInfo *ABI) {
+  if (CountPlusOneBound *OT = dyn_cast_or_null<CountPlusOneBound>(O))
+    return ABI->areSameProgramVar(this->CountVar, OT->CountVar);
+  return false;
+}
+
 std::string ByteBound::mkString(AVarBoundsInfo *ABI, clang::Decl *D) {
   return "byte_count(" + ABounds::getBoundsKeyStr(ByteVar, ABI, D) + ")";
 }
 
 bool ByteBound::areSame(ABounds *O, AVarBoundsInfo *ABI) {
-  if (O != nullptr) {
-    if (ByteBound *BB = dyn_cast<ByteBound>(O)) {
-      return ABI->areSameProgramVar(this->ByteVar, BB->ByteVar);
-    }
-  }
+  if (ByteBound *BB = dyn_cast_or_null<ByteBound>(O))
+    return ABI->areSameProgramVar(this->ByteVar, BB->ByteVar);
   return false;
 }
 
@@ -118,11 +130,8 @@ std::string RangeBound::mkString(AVarBoundsInfo *ABI, clang::Decl *D) {
 }
 
 bool RangeBound::areSame(ABounds *O, AVarBoundsInfo *ABI) {
-  if (O != nullptr) {
-    if (RangeBound *RB = dyn_cast<RangeBound>(O)) {
-      return ABI->areSameProgramVar(this->LB, RB->LB) &&
-             ABI->areSameProgramVar(this->UB, RB->UB);
-    }
-  }
+  if (RangeBound *RB = dyn_cast_or_null<RangeBound>(O))
+    return ABI->areSameProgramVar(this->LB, RB->LB) &&
+           ABI->areSameProgramVar(this->UB, RB->UB);
   return false;
 }