Commit 84a01a60 authored by Tanya Lattner's avatar Tanya Lattner
Browse files

Merge from mainline. 

Disallow the construction of SCEVs with could-not-compute operands. Catch CNCs
returned by BinomialCoefficient and don't try to operate with them. This
replaces the previous fix for PR2857.

llvm-svn: 57958
parent 2e505e9a

llvm/lib/Analysis/ScalarEvolution.cpp

+6 −72
Original line number Diff line number Diff line
@@ -644,11 +644,12 @@ SCEVHandle SCEVAddRecExpr::evaluateAtIteration(SCEVHandle It, 
    // The computation is correct in the face of overflow provided that the

    // multiplication is performed _after_ the evaluation of the binomial

    // coefficient.

    SCEVHandle Val =

      SE.getMulExpr(getOperand(i),

                    BinomialCoefficient(It, i, SE,

                                        cast<IntegerType>(getType())));

    Result = SE.getAddExpr(Result, Val);

    SCEVHandle Coeff = BinomialCoefficient(It, i, SE,

                                           cast<IntegerType>(getType()));

    if (isa<SCEVCouldNotCompute>(Coeff))

      return Coeff;



    Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));

  }

  return Result;

}
@@ -676,9 +677,6 @@ SCEVHandle ScalarEvolution::getTruncateExpr(const SCEVHandle &Op, const Type *Ty 
      return getAddRecExpr(Operands, AddRec->getLoop());

  }



  if (isa<SCEVCouldNotCompute>(Op))

    return new SCEVCouldNotCompute();



  SCEVTruncateExpr *&Result = (*SCEVTruncates)[std::make_pair(Op, Ty)];

  if (Result == 0) Result = new SCEVTruncateExpr(Op, Ty);

  return Result;
@@ -694,9 +692,6 @@ SCEVHandle ScalarEvolution::getZeroExtendExpr(const SCEVHandle &Op, const Type * 
  // operands (often constants).  This would allow analysis of something like

  // this:  for (unsigned char X = 0; X < 100; ++X) { int Y = X; }



  if (isa<SCEVCouldNotCompute>(Op))

    return new SCEVCouldNotCompute();



  SCEVZeroExtendExpr *&Result = (*SCEVZeroExtends)[std::make_pair(Op, Ty)];

  if (Result == 0) Result = new SCEVZeroExtendExpr(Op, Ty);

  return Result;
@@ -712,9 +707,6 @@ SCEVHandle ScalarEvolution::getSignExtendExpr(const SCEVHandle &Op, const Type * 
  // operands (often constants).  This would allow analysis of something like

  // this:  for (signed char X = 0; X < 100; ++X) { int Y = X; }



  if (isa<SCEVCouldNotCompute>(Op))

    return new SCEVCouldNotCompute();



  SCEVSignExtendExpr *&Result = (*SCEVSignExtends)[std::make_pair(Op, Ty)];

  if (Result == 0) Result = new SCEVSignExtendExpr(Op, Ty);

  return Result;
@@ -743,10 +735,6 @@ SCEVHandle ScalarEvolution::getAddExpr(std::vector<SCEVHandle> &Ops) { 
  // Sort by complexity, this groups all similar expression types together.

  GroupByComplexity(Ops);



  // Could not compute plus anything equals could not compute.

  if (isa<SCEVCouldNotCompute>(Ops.back()))

    return new SCEVCouldNotCompute();



  // If there are any constants, fold them together.

  unsigned Idx = 0;

  if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
@@ -972,21 +960,6 @@ SCEVHandle ScalarEvolution::getMulExpr(std::vector<SCEVHandle> &Ops) { 
  // Sort by complexity, this groups all similar expression types together.

  GroupByComplexity(Ops);



  if (isa<SCEVCouldNotCompute>(Ops.back())) {

    // CNC * 0 = 0

    for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {

      if (Ops[i]->getSCEVType() != scConstant)

        break;



      SCEVConstant *SC = cast<SCEVConstant>(Ops[i]);

      if (SC->getValue()->isMinValue(false))

        return SC;

    }



    // Otherwise, we can't compute it.

    return new SCEVCouldNotCompute();

  }



  // If there are any constants, fold them together.

  unsigned Idx = 0;

  if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
@@ -1152,9 +1125,6 @@ SCEVHandle ScalarEvolution::getUDivExpr(const SCEVHandle &LHS, const SCEVHandle 


  // FIXME: implement folding of (X*4)/4 when we know X*4 doesn't overflow.



  if (isa<SCEVCouldNotCompute>(LHS) || isa<SCEVCouldNotCompute>(RHS))

    return new SCEVCouldNotCompute();



  SCEVUDivExpr *&Result = (*SCEVUDivs)[std::make_pair(LHS, RHS)];

  if (Result == 0) Result = new SCEVUDivExpr(LHS, RHS);

  return Result;
@@ -1202,12 +1172,6 @@ SCEVHandle ScalarEvolution::getAddRecExpr(std::vector<SCEVHandle> &Operands, 
    }

  }



  // Refuse to build an AddRec out of SCEVCouldNotCompute.

  for (unsigned i = 0, e = Operands.size(); i != e; ++i) {

    if (isa<SCEVCouldNotCompute>(Operands[i]))

      return new SCEVCouldNotCompute();

  }



  SCEVAddRecExpr *&Result =

    (*SCEVAddRecExprs)[std::make_pair(L, std::vector<SCEV*>(Operands.begin(),

                                                            Operands.end()))];
@@ -1230,21 +1194,6 @@ SCEVHandle ScalarEvolution::getSMaxExpr(std::vector<SCEVHandle> Ops) { 
  // Sort by complexity, this groups all similar expression types together.

  GroupByComplexity(Ops);



  if (isa<SCEVCouldNotCompute>(Ops.back())) {

    // CNC smax +inf = +inf.

    for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {

      if (Ops[i]->getSCEVType() != scConstant)

        break;



      SCEVConstant *SC = cast<SCEVConstant>(Ops[i]);

      if (SC->getValue()->isMaxValue(true))

        return SC;

    }



    // Otherwise, we can't compute it.

    return new SCEVCouldNotCompute();

  }



  // If there are any constants, fold them together.

  unsigned Idx = 0;

  if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
@@ -1325,21 +1274,6 @@ SCEVHandle ScalarEvolution::getUMaxExpr(std::vector<SCEVHandle> Ops) { 
  // Sort by complexity, this groups all similar expression types together.

  GroupByComplexity(Ops);



  if (isa<SCEVCouldNotCompute>(Ops[0])) {

    // CNC umax inf = inf.

    for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {

      if (Ops[i]->getSCEVType() != scConstant)

        break;



      SCEVConstant *SC = cast<SCEVConstant>(Ops[i]);

      if (SC->getValue()->isMaxValue(false))

        return SC;

    }



    // Otherwise, we can't compute it.

    return new SCEVCouldNotCompute();

  }



  // If there are any constants, fold them together.

  unsigned Idx = 0;

  if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {