Change SCEVNAryExpr's operand array from a SmallVector to a plain

pointer and length, and allocate the arrays in ScalarEvolution's
BumpPtrAllocator, so that they get released when their owning
SCEV gets released. SCEVs are immutable, so they don't need to worry
about operand array resizing. This fixes a memory leak reported
in PR6637.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98755 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/ScalarEvolutionExpressions.h b/include/llvm/Analysis/ScalarEvolutionExpressions.h
index 0ab3b3f4a5e2ad40d4b061ca64638551da31264c..27539a3753fc05c1b1c6b6f5e63561ff962438ed 100644 (file)
--- a/include/llvm/Analysis/ScalarEvolutionExpressions.h
+++ b/include/llvm/Analysis/ScalarEvolutionExpressions.h
@@ -180,25 +180,27 @@ namespace llvm {
   ///
   class SCEVNAryExpr : public SCEV {
   protected:
-    SmallVector<const SCEV *, 8> Operands;
+    // Since SCEVs are immutable, ScalarEvolution allocates operand
+    // arrays with its SCEVAllocator, so this class just needs a simple
+    // pointer rather than a more elaborate vector-like data structure.
+    // This also avoids the need for a non-trivial destructor.
+    const SCEV *const *Operands;
+    size_t NumOperands;
 
     SCEVNAryExpr(const FoldingSetNodeID &ID,
-                 enum SCEVTypes T, const SmallVectorImpl<const SCEV *> &ops)
-      : SCEV(ID, T), Operands(ops.begin(), ops.end()) {}
+                 enum SCEVTypes T, const SCEV *const *O, size_t N)
+      : SCEV(ID, T), Operands(O), NumOperands(N) {}
 
   public:
-    unsigned getNumOperands() const { return (unsigned)Operands.size(); }
+    size_t getNumOperands() const { return NumOperands; }
     const SCEV *getOperand(unsigned i) const {
-      assert(i < Operands.size() && "Operand index out of range!");
+      assert(i < NumOperands && "Operand index out of range!");
       return Operands[i];
     }
 
-    const SmallVectorImpl<const SCEV *> &getOperands() const {
-      return Operands;
-    }
-    typedef SmallVectorImpl<const SCEV *>::const_iterator op_iterator;
-    op_iterator op_begin() const { return Operands.begin(); }
-    op_iterator op_end() const { return Operands.end(); }
+    typedef const SCEV *const *op_iterator;
+    op_iterator op_begin() const { return Operands; }
+    op_iterator op_end() const { return Operands + NumOperands; }
 
     virtual bool isLoopInvariant(const Loop *L) const {
       for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
@@ -262,8 +264,8 @@ namespace llvm {
   protected:
     SCEVCommutativeExpr(const FoldingSetNodeID &ID,
                         enum SCEVTypes T,
-                        const SmallVectorImpl<const SCEV *> &ops)
-      : SCEVNAryExpr(ID, T, ops) {}
+                        const SCEV *const *O, size_t N)
+      : SCEVNAryExpr(ID, T, O, N) {}
 
   public:
     virtual const char *getOperationStr() const = 0;
@@ -288,8 +290,8 @@ namespace llvm {
     friend class ScalarEvolution;
 
     SCEVAddExpr(const FoldingSetNodeID &ID,
-                const SmallVectorImpl<const SCEV *> &ops)
-      : SCEVCommutativeExpr(ID, scAddExpr, ops) {
+                const SCEV *const *O, size_t N)
+      : SCEVCommutativeExpr(ID, scAddExpr, O, N) {
     }
 
   public:
@@ -316,8 +318,8 @@ namespace llvm {
     friend class ScalarEvolution;
 
     SCEVMulExpr(const FoldingSetNodeID &ID,
-                const SmallVectorImpl<const SCEV *> &ops)
-      : SCEVCommutativeExpr(ID, scMulExpr, ops) {
+                const SCEV *const *O, size_t N)
+      : SCEVCommutativeExpr(ID, scMulExpr, O, N) {
     }
 
   public:
@@ -390,9 +392,9 @@ namespace llvm {
     const Loop *L;
 
     SCEVAddRecExpr(const FoldingSetNodeID &ID,
-                   const SmallVectorImpl<const SCEV *> &ops, const Loop *l)
-      : SCEVNAryExpr(ID, scAddRecExpr, ops), L(l) {
-      for (size_t i = 0, e = Operands.size(); i != e; ++i)
+                   const SCEV *const *O, size_t N, const Loop *l)
+      : SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) {
+      for (size_t i = 0, e = NumOperands; i != e; ++i)
         assert(Operands[i]->isLoopInvariant(l) &&
                "Operands of AddRec must be loop-invariant!");
     }
@@ -472,8 +474,8 @@ namespace llvm {
     friend class ScalarEvolution;
 
     SCEVSMaxExpr(const FoldingSetNodeID &ID,
-                 const SmallVectorImpl<const SCEV *> &ops)
-      : SCEVCommutativeExpr(ID, scSMaxExpr, ops) {
+                 const SCEV *const *O, size_t N)
+      : SCEVCommutativeExpr(ID, scSMaxExpr, O, N) {
       // Max never overflows.
       setHasNoUnsignedWrap(true);
       setHasNoSignedWrap(true);
@@ -497,8 +499,8 @@ namespace llvm {
     friend class ScalarEvolution;
 
     SCEVUMaxExpr(const FoldingSetNodeID &ID,
-                 const SmallVectorImpl<const SCEV *> &ops)
-      : SCEVCommutativeExpr(ID, scUMaxExpr, ops) {
+                 const SCEV *const *O, size_t N)
+      : SCEVCommutativeExpr(ID, scUMaxExpr, O, N) {
       // Max never overflows.
       setHasNoUnsignedWrap(true);
       setHasNoSignedWrap(true);

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 15f072dbeb7e87b0d3b2882a7db0c1846c815ea2..12042c2ee6467a4da1736cdc9fe77d1100abbabd 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -248,10 +248,10 @@ void SCEVSignExtendExpr::print(raw_ostream &OS) const {
 }
 
 void SCEVCommutativeExpr::print(raw_ostream &OS) const {
-  assert(Operands.size() > 1 && "This plus expr shouldn't exist!");
+  assert(NumOperands > 1 && "This plus expr shouldn't exist!");
   const char *OpStr = getOperationStr();
   OS << "(" << *Operands[0];
-  for (unsigned i = 1, e = Operands.size(); i != e; ++i)
+  for (unsigned i = 1, e = NumOperands; i != e; ++i)
     OS << OpStr << *Operands[i];
   OS << ")";
 }
@@ -329,7 +329,7 @@ SCEVAddRecExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
 
 void SCEVAddRecExpr::print(raw_ostream &OS) const {
   OS << "{" << *Operands[0];
-  for (unsigned i = 1, e = Operands.size(); i != e; ++i)
+  for (unsigned i = 1, e = NumOperands; i != e; ++i)
     OS << ",+," << *Operands[i];
   OS << "}<";
   WriteAsOperand(OS, L->getHeader(), /*PrintType=*/false);
@@ -1202,23 +1202,23 @@ static bool
 CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
                              SmallVector<const SCEV *, 8> &NewOps,
                              APInt &AccumulatedConstant,
-                             const SmallVectorImpl<const SCEV *> &Ops,
+                             const SCEV *const *Ops, size_t NumOperands,
                              const APInt &Scale,
                              ScalarEvolution &SE) {
   bool Interesting = false;
 
   // Iterate over the add operands.
-  for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
+  for (unsigned i = 0, e = NumOperands; i != e; ++i) {
     const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
     if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
       APInt NewScale =
         Scale * cast<SCEVConstant>(Mul->getOperand(0))->getValue()->getValue();
       if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
         // A multiplication of a constant with another add; recurse.
+        const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
         Interesting |=
           CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
-                                       cast<SCEVAddExpr>(Mul->getOperand(1))
-                                         ->getOperands(),
+                                       Add->op_begin(), Add->getNumOperands(),
                                        NewScale, SE);
       } else {
         // A multiplication of a constant with some other value. Update
@@ -1427,7 +1427,8 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
     SmallVector<const SCEV *, 8> NewOps;
     APInt AccumulatedConstant(BitWidth, 0);
     if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
-                                     Ops, APInt(BitWidth, 1), *this)) {
+                                     Ops.data(), Ops.size(),
+                                     APInt(BitWidth, 1), *this)) {
       // Some interesting folding opportunity is present, so its worthwhile to
       // re-generate the operands list. Group the operands by constant scale,
       // to avoid multiplying by the same constant scale multiple times.
@@ -1612,7 +1613,9 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
     static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
   if (!S) {
     S = SCEVAllocator.Allocate<SCEVAddExpr>();
-    new (S) SCEVAddExpr(ID, Ops);
+    const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
+    std::uninitialized_copy(Ops.begin(), Ops.end(), O);
+    new (S) SCEVAddExpr(ID, O, Ops.size());
     UniqueSCEVs.InsertNode(S, IP);
   }
   if (HasNUW) S->setHasNoUnsignedWrap(true);
@@ -1820,7 +1823,9 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
     static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
   if (!S) {
     S = SCEVAllocator.Allocate<SCEVMulExpr>();
-    new (S) SCEVMulExpr(ID, Ops);
+    const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
+    std::uninitialized_copy(Ops.begin(), Ops.end(), O);
+    new (S) SCEVMulExpr(ID, O, Ops.size());
     UniqueSCEVs.InsertNode(S, IP);
   }
   if (HasNUW) S->setHasNoUnsignedWrap(true);
@@ -1880,9 +1885,7 @@ const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
           const SCEV *Op = M->getOperand(i);
           const SCEV *Div = getUDivExpr(Op, RHSC);
           if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
-            const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
-            Operands = SmallVector<const SCEV *, 4>(MOperands.begin(),
-                                                  MOperands.end());
+            Operands = SmallVector<const SCEV *, 4>(M->op_begin(), M->op_end());
             Operands[i] = Div;
             return getMulExpr(Operands);
           }
@@ -2031,7 +2034,9 @@ ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
     static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
   if (!S) {
     S = SCEVAllocator.Allocate<SCEVAddRecExpr>();
-    new (S) SCEVAddRecExpr(ID, Operands, L);
+    const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Operands.size());
+    std::uninitialized_copy(Operands.begin(), Operands.end(), O);
+    new (S) SCEVAddRecExpr(ID, O, Operands.size(), L);
     UniqueSCEVs.InsertNode(S, IP);
   }
   if (HasNUW) S->setHasNoUnsignedWrap(true);
@@ -2131,7 +2136,9 @@ ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
   void *IP = 0;
   if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
   SCEV *S = SCEVAllocator.Allocate<SCEVSMaxExpr>();
-  new (S) SCEVSMaxExpr(ID, Ops);
+  const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
+  std::uninitialized_copy(Ops.begin(), Ops.end(), O);
+  new (S) SCEVSMaxExpr(ID, O, Ops.size());
   UniqueSCEVs.InsertNode(S, IP);
   return S;
 }
@@ -2228,7 +2235,9 @@ ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
   void *IP = 0;
   if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
   SCEV *S = SCEVAllocator.Allocate<SCEVUMaxExpr>();
-  new (S) SCEVUMaxExpr(ID, Ops);
+  const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
+  std::uninitialized_copy(Ops.begin(), Ops.end(), O);
+  new (S) SCEVUMaxExpr(ID, O, Ops.size());
   UniqueSCEVs.InsertNode(S, IP);
   return S;
 }

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index 3c2cbfbe78ebac1bc3e9e3666e4b2ac99b185a81..5b3a39802aa9261ea51fc15c5af02945ea92f46e 100644 (file)
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -232,9 +232,7 @@ static bool FactorOutConstant(const SCEV *&S,
       const SCEVConstant *FC = cast<SCEVConstant>(Factor);
       if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
         if (!C->getValue()->getValue().srem(FC->getValue()->getValue())) {
-          const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
-          SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
-                                                 MOperands.end());
+          SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
           NewMulOps[0] =
             SE.getConstant(C->getValue()->getValue().sdiv(
                                                    FC->getValue()->getValue()));
@@ -249,9 +247,7 @@ static bool FactorOutConstant(const SCEV *&S,
         const SCEV *Remainder = SE.getIntegerSCEV(0, SOp->getType());
         if (FactorOutConstant(SOp, Remainder, Factor, SE, TD) &&
             Remainder->isZero()) {
-          const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands();
-          SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(),
-                                                 MOperands.end());
+          SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
           NewMulOps[i] = SOp;
           S = SE.getMulExpr(NewMulOps);
           return true;
@@ -297,13 +293,11 @@ static void SimplifyAddOperands(SmallVectorImpl<const SCEV *> &Ops,
                     SE.getAddExpr(NoAddRecs);
   // If it returned an add, use the operands. Otherwise it simplified
   // the sum into a single value, so just use that.
+  Ops.clear();
   if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum))
-    Ops = Add->getOperands();
-  else {
-    Ops.clear();
-    if (!Sum->isZero())
-      Ops.push_back(Sum);
-  }
+    Ops.insert(Ops.end(), Add->op_begin(), Add->op_begin());
+  else if (!Sum->isZero())
+    Ops.push_back(Sum);
   // Then append the addrecs.
   Ops.insert(Ops.end(), AddRecs.begin(), AddRecs.end());
 }
@@ -1060,10 +1054,9 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
   if (CanonicalIV &&
       SE.getTypeSizeInBits(CanonicalIV->getType()) >
       SE.getTypeSizeInBits(Ty)) {
-    const SmallVectorImpl<const SCEV *> &Ops = S->getOperands();
-    SmallVector<const SCEV *, 4> NewOps(Ops.size());
-    for (unsigned i = 0, e = Ops.size(); i != e; ++i)
-      NewOps[i] = SE.getAnyExtendExpr(Ops[i], CanonicalIV->getType());
+    SmallVector<const SCEV *, 4> NewOps(S->getNumOperands());
+    for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i)
+      NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
     Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop()));
     BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
     BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
@@ -1078,8 +1071,7 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
 
   // {X,+,F} --> X + {0,+,F}
   if (!S->getStart()->isZero()) {
-    const SmallVectorImpl<const SCEV *> &SOperands = S->getOperands();
-    SmallVector<const SCEV *, 4> NewOps(SOperands.begin(), SOperands.end());
+    SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end());
     NewOps[0] = SE.getIntegerSCEV(0, Ty);
     const SCEV *Rest = SE.getAddRecExpr(NewOps, L);