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Add alternate ConstantRange intersection algorithm.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39851 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2007-07-14 02:51:34 +00:00
parent 7722ceb7de
commit 377b1190cb
2 changed files with 87 additions and 0 deletions
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6
include/llvm/Support/ConstantRange.h
View File

@ -143,6 +143,12 @@ class ConstantRange {
///
ConstantRange intersectWith(const ConstantRange &CR) const;
/// maximalIntersectWith - Return the range that results from the intersection
/// of this range with another range. The resultant range is guaranteed to
/// include all elements contained in both input ranges, and is also
/// guaranteed to be the smallest possible set that does so.
ConstantRange maximalIntersectWith(const ConstantRange &CR) const;
/// unionWith - Return the range that results from the union of this range
/// with another range. The resultant range is guaranteed to include the
/// elements of both sets, but may contain more. For example, [3, 9) union

81
lib/Support/ConstantRange.cpp
View File

@ -246,6 +246,87 @@ ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
return *this;
}
/// maximalIntersectWith - Return the range that results from the intersection
/// of this range with another range. The resultant range is guaranteed to
/// include all elements contained in both input ranges, and is also guaranteed
/// to be the smallest possible set that does so.
ConstantRange ConstantRange::maximalIntersectWith(const ConstantRange &CR) const {
assert(getBitWidth() == CR.getBitWidth() &&
"ConstantRange types don't agree!");
// Handle common cases.
if ( isEmptySet() || CR.isFullSet()) return *this;
if (CR.isEmptySet() || isFullSet()) return CR;
if (!isWrappedSet() && CR.isWrappedSet())
return CR.maximalIntersectWith(*this);
if (!isWrappedSet() && !CR.isWrappedSet()) {
if (Lower.ult(CR.Lower)) {
if (Upper.ule(CR.Lower))
return ConstantRange(getBitWidth(), false);
if (Upper.ult(CR.Upper))
return ConstantRange(CR.Lower, Upper);
return CR;
} else {
if (Upper.ult(CR.Upper))
return *this;
if (Lower.ult(CR.Upper))
return ConstantRange(Lower, CR.Upper);
return ConstantRange(getBitWidth(), false);
}
}
if (isWrappedSet() && !CR.isWrappedSet()) {
if (CR.Lower.ult(Upper)) {
if (CR.Upper.ult(Upper))
return CR;
if (CR.Upper.ult(Lower))
return ConstantRange(CR.Lower, Upper);
if (getSetSize().ult(CR.getSetSize()))
return *this;
else
return CR;
} else if (CR.Lower.ult(Lower)) {
if (CR.Upper.ule(Lower))
return ConstantRange(getBitWidth(), false);
return ConstantRange(Lower, CR.Upper);
}
return CR;
}
if (CR.Upper.ult(Upper)) {
if (CR.Lower.ult(Upper)) {
if (getSetSize().ult(CR.getSetSize()))
return *this;
else
return CR;
}
if (CR.Lower.ult(Lower))
return ConstantRange(Lower, CR.Upper);
return CR;
} else if (CR.Upper.ult(Lower)) {
if (CR.Lower.ult(Lower))
return *this;
return ConstantRange(CR.Lower, Upper);
}
if (getSetSize().ult(CR.getSetSize()))
return *this;
else
return CR;
}
/// unionWith - Return the range that results from the union of this range with
/// another range. The resultant range is guaranteed to include the elements of
/// both sets, but may contain more. For example, [3, 9) union [12,15) is