diff options
Diffstat (limited to 'lib/Analysis/ScalarEvolution.cpp')
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index b973203a89b66..9539fd7c75596 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -162,6 +162,11 @@ static cl::opt<unsigned> cl::desc("Maximum depth of recursive SExt/ZExt"), cl::init(8)); +static cl::opt<unsigned> + MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden, + cl::desc("Max coefficients in AddRec during evolving"), + cl::init(16)); + //===----------------------------------------------------------------------===// // SCEV class definitions //===----------------------------------------------------------------------===// @@ -2878,6 +2883,12 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop) continue; + // Limit max number of arguments to avoid creation of unreasonably big + // SCEVAddRecs with very complex operands. + if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 > + MaxAddRecSize) + continue; + bool Overflow = false; Type *Ty = AddRec->getType(); bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64; @@ -7582,6 +7593,25 @@ const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) { const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI); if (const SCEVConstant *BTCC = dyn_cast<SCEVConstant>(BackedgeTakenCount)) { + + // This trivial case can show up in some degenerate cases where + // the incoming IR has not yet been fully simplified. + if (BTCC->getValue()->isZero()) { + Value *InitValue = nullptr; + bool MultipleInitValues = false; + for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) { + if (!LI->contains(PN->getIncomingBlock(i))) { + if (!InitValue) + InitValue = PN->getIncomingValue(i); + else if (InitValue != PN->getIncomingValue(i)) { + MultipleInitValues = true; + break; + } + } + if (!MultipleInitValues && InitValue) + return getSCEV(InitValue); + } + } // Okay, we know how many times the containing loop executes. If // this is a constant evolving PHI node, get the final value at // the specified iteration number. |