diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index f0bc9360b16..179aa8867d6 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -2442,6 +2442,10 @@ const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) { /// const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS) { + // Fast path: X - X --> 0. + if (LHS == RHS) + return getConstant(LHS->getType(), 0); + // X - Y --> X + -Y return getAddExpr(LHS, getNegativeSCEV(RHS)); }