Initial implementation of ConstantRange support

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3564 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Support/ConstantRange.h b/include/llvm/Support/ConstantRange.h
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+++ b/include/llvm/Support/ConstantRange.h
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+//===-- llvm/Support/ConstantRange.h - Represent a range --------*- C++ -*-===//
+//
+// Represent a range of possible values that may occur when the program is run
+// for an integral value.  This keeps track of a lower and upper bound for the
+// constant, which MAY wrap around the end of the numeric range.  To do this, it
+// keeps track of a [lower, upper) bound, which specifies an interval just like
+// STL iterators.  When used with boolean values, the following are important
+// ranges (other integral ranges use min/max values for special range values):
+//
+//  [F, F) = {}     = Empty set
+//  [T, F) = {T}
+//  [F, T) = {F}
+//  [T, T) = {F, T} = Full set
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_CONSTANT_RANGE_H
+#define LLVM_SUPPORT_CONSTANT_RANGE_H
+
+#include "Support/DataTypes.h"
+class ConstantIntegral;
+class Type;
+
+class ConstantRange {
+  ConstantIntegral *Lower, *Upper;
+ public:
+  /// Initialize a full (the default) or empty set for the specified type.
+  ///
+  ConstantRange(const Type *Ty, bool isFullSet = true);
+  
+  /// Initialize a range of values explicitly... this will assert out if
+  /// Lower==Upper and Lower != Min or Max for its type (or if the two constants
+  /// have different types)
+  ///
+  ConstantRange(ConstantIntegral *Lower, ConstantIntegral *Upper);
+  
+  /// Initialize a set of values that all satisfy the condition with C.
+  ///
+  ConstantRange(unsigned SetCCOpcode, ConstantIntegral *C);
+  
+  /// getLower - Return the lower value for this range...
+  ///
+  ConstantIntegral *getLower() const { return Lower; }
+
+  /// getUpper - Return the upper value for this range...
+  ///
+  ConstantIntegral *getUpper() const { return Upper; }
+
+  /// getType - Return the LLVM data type of this range.
+  ///
+  const Type *getType() const;
+  
+  /// isFullSet - Return true if this set contains all of the elements possible
+  /// for this data-type
+  ///
+  bool isFullSet() const;
+  
+  /// isEmptySet - Return true if this set contains no members.
+  ///
+  bool isEmptySet() const;
+
+  /// isWrappedSet - Return true if this set wraps around the top of the range,
+  /// for example: [100, 8)
+  ///
+  bool isWrappedSet() const;
+  
+  /// getSingleElement - If this set contains a single element, return it,
+  /// otherwise return null.
+  ///
+  ConstantIntegral *getSingleElement() const;
+  
+  /// isSingleElement - Return true if this set contains exactly one member.
+  ///
+  bool isSingleElement() const { return getSingleElement() != 0; }
+
+  /// getSetSize - Return the number of elements in this set.
+  ///
+  uint64_t getSetSize() const;
+
+  /// intersect - Return the range that results from the intersection of this
+  /// range with another range.  The resultant range is pruned as much as
+  /// possible, but there may be cases where elements are included that are in
+  /// one of the sets but not the other.  For example: [100, 8) intersect [3,
+  /// 120) yields [3, 120)
+  ///
+  ConstantRange intersectWith(const ConstantRange &CR) const;
+
+  /// union - 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
+  /// [3, 15), which includes 9, 10, and 11, which were not included in either
+  /// set before.
+  ///
+  ConstantRange unionWith(const ConstantRange &CR) const;
+};
+
+#endif