diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 9982f1d71f6..94999ad66b3 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -414,20 +414,28 @@ static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS, if (LHS == RHS) return SE.getConstant(LHS->getType(), 1); - // Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do some - // folding. - if (RHS->isAllOnesValue()) - return SE.getMulExpr(LHS, RHS); + // Handle a few RHS special cases. + const SCEVConstant *RC = dyn_cast(RHS); + if (RC) { + const APInt &RA = RC->getValue()->getValue(); + // Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do + // some folding. + if (RA.isAllOnesValue()) + return SE.getMulExpr(LHS, RC); + // Handle x /s 1 as x. + if (RA == 1) + return LHS; + } // Check for a division of a constant by a constant. if (const SCEVConstant *C = dyn_cast(LHS)) { - const SCEVConstant *RC = dyn_cast(RHS); if (!RC) return 0; - if (C->getValue()->getValue().srem(RC->getValue()->getValue()) != 0) + const APInt &LA = C->getValue()->getValue(); + const APInt &RA = RC->getValue()->getValue(); + if (LA.srem(RA) != 0) return 0; - return SE.getConstant(C->getValue()->getValue() - .sdiv(RC->getValue()->getValue())); + return SE.getConstant(LA.sdiv(RA)); } // Distribute the sdiv over addrec operands, if the addrec doesn't overflow.