+ APInt MaxValue = APInt::getMaxValue(DstTySize).zext(getBitWidth());
+ APInt MaxBitValue(getBitWidth(), 0);
+ MaxBitValue.setBit(DstTySize);
+
+ APInt LowerDiv(Lower), UpperDiv(Upper);
+ ConstantRange Union(DstTySize, /*isFullSet=*/false);
+
+ // Analyze wrapped sets in their two parts: [0, Upper) \/ [Lower, MaxValue]
+ // We use the non-wrapped set code to analyze the [Lower, MaxValue) part, and
+ // then we do the union with [MaxValue, Upper)
+ if (isWrappedSet()) {
+ // if Upper is greater than Max Value, it covers the whole truncated range.
+ if (Upper.uge(MaxValue))
+ return ConstantRange(DstTySize, /*isFullSet=*/true);
+
+ Union = ConstantRange(APInt::getMaxValue(DstTySize),Upper.trunc(DstTySize));
+ UpperDiv = APInt::getMaxValue(getBitWidth());
+
+ // Union covers the MaxValue case, so return if the remaining range is just
+ // MaxValue.
+ if (LowerDiv == UpperDiv)
+ return Union;
+ }
+
+ // Chop off the most significant bits that are past the destination bitwidth.
+ if (LowerDiv.uge(MaxValue)) {
+ APInt Div(getBitWidth(), 0);
+ APInt::udivrem(LowerDiv, MaxBitValue, Div, LowerDiv);
+ UpperDiv = UpperDiv - MaxBitValue * Div;
+ }
+
+ if (UpperDiv.ule(MaxValue))
+ return ConstantRange(LowerDiv.trunc(DstTySize),
+ UpperDiv.trunc(DstTySize)).unionWith(Union);
+
+ // The truncated value wrapps around. Check if we can do better than fullset.
+ APInt UpperModulo = UpperDiv - MaxBitValue;
+ if (UpperModulo.ult(LowerDiv))
+ return ConstantRange(LowerDiv.trunc(DstTySize),
+ UpperModulo.trunc(DstTySize)).unionWith(Union);
+
+ return ConstantRange(DstTySize, /*isFullSet=*/true);