[MLIR][Presburger] MPInt: gcd: assert that operands are non-negative

Author: Superty

mlir/include/mlir/Analysis/Presburger/MPInt.h

@@ -195,6 +195,7 @@ class MPInt {
  friend MPInt gcdRange(ArrayRef<MPInt> range);
  friend MPInt ceilDiv(const MPInt &lhs, const MPInt &rhs);
  friend MPInt floorDiv(const MPInt &lhs, const MPInt &rhs);
+ // The operands must be non-negative for gcd.
  friend MPInt gcd(const MPInt &a, const MPInt &b);
  friend MPInt lcm(const MPInt &a, const MPInt &b);
  friend MPInt mod(const MPInt &lhs, const MPInt &rhs);
@@ -382,6 +383,7 @@ LLVM_ATTRIBUTE_ALWAYS_INLINE MPInt mod(const MPInt &lhs, const MPInt &rhs) {
 }
 
 LLVM_ATTRIBUTE_ALWAYS_INLINE MPInt gcd(const MPInt &a, const MPInt &b) {
+ assert(a >= 0 && b >= 0 && "operands must be non-negative!");
  if (LLVM_LIKELY(a.isSmall() && b.isSmall()))
  return MPInt(llvm::greatestCommonDivisor(a.getSmall(), b.getSmall()));
  return MPInt(gcd(detail::SlowMPInt(a), detail::SlowMPInt(b)));