diff options
Diffstat (limited to 'lib/Analysis/ScalarEvolution.cpp')
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index ea45e9d72c..f35f11615f 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -5119,7 +5119,7 @@ SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) { // Compute the two solutions for the quadratic formula. // The divisions must be performed as signed divisions. APInt NegB(-B); - APInt TwoA( A << 1 ); + APInt TwoA(A << 1); if (TwoA.isMinValue()) { const SCEV *CNC = SE.getCouldNotCompute(); return std::make_pair(CNC, CNC); @@ -5134,7 +5134,7 @@ SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) { return std::make_pair(SE.getConstant(Solution1), SE.getConstant(Solution2)); - } // end APIntOps namespace + } // end APIntOps namespace } /// HowFarToZero - Return the number of times a backedge comparing the specified @@ -5228,8 +5228,19 @@ ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L) { // Handle unitary steps, which cannot wraparound. // 1*N = -Start; -1*N = Start (mod 2^BW), so: // N = Distance (as unsigned) - if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue()) - return Distance; + if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue()) { + ConstantRange CR = getUnsignedRange(Start); + const SCEV *MaxBECount; + if (!CountDown && CR.getUnsignedMin().isMinValue()) + // When counting up, the worst starting value is 1, not 0. + MaxBECount = CR.getUnsignedMax().isMinValue() + ? getConstant(APInt::getMinValue(CR.getBitWidth())) + : getConstant(APInt::getMaxValue(CR.getBitWidth())); + else + MaxBECount = getConstant(CountDown ? CR.getUnsignedMax() + : -CR.getUnsignedMin()); + return ExitLimit(Distance, MaxBECount); + } // If the recurrence is known not to wraparound, unsigned divide computes the // back edge count. We know that the value will either become zero (and thus |