Move ConstantRange class to lib/Support from lib/Analysis and make its

interface not depend on Type or ICmpInst.

llvm-svn: 34761

1 files changed, 259 insertions, 0 deletions

diff --git a/llvm/lib/Support/ConstantRange.cpp b/llvm/lib/Support/ConstantRange.cpp
new file mode 100644
index 00000000000..ba3c4723b46
--- /dev/null
+++ b/llvm/lib/Support/ConstantRange.cpp
@@ -0,0 +1,259 @@
+//===-- ConstantRange.cpp - ConstantRange implementation ------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/ConstantRange.h"
+#include "llvm/Support/Streams.h"
+#include <ostream>
+using namespace llvm;
+
+/// Initialize a full (the default) or empty set for the specified type.
+///
+ConstantRange::ConstantRange(uint32_t BitWidth, bool Full) :
+  Lower(BitWidth, 0), Upper(BitWidth, 0) {
+  if (Full)
+    Lower = Upper = APInt::getMaxValue(BitWidth);
+  else
+    Lower = Upper = APInt::getMinValue(BitWidth);
+}
+
+/// Initialize a range to hold the single specified value.
+///
+ConstantRange::ConstantRange(const APInt & V) : Lower(V), Upper(V + 1) { }
+
+ConstantRange::ConstantRange(const APInt &L, const APInt &U) :
+  Lower(L), Upper(U) {
+  assert(L.getBitWidth() == U.getBitWidth() && 
+         "ConstantRange with unequal bit widths");
+  uint32_t BitWidth = L.getBitWidth();
+  assert((L != U || (L == APInt::getMaxValue(BitWidth) ||
+                     L == APInt::getMinValue(BitWidth))) &&
+         "Lower == Upper, but they aren't min or max value!");
+}
+
+/// isFullSet - Return true if this set contains all of the elements possible
+/// for this data-type
+bool ConstantRange::isFullSet() const {
+  return Lower == Upper && Lower == APInt::getMaxValue(getBitWidth());
+}
+
+/// isEmptySet - Return true if this set contains no members.
+///
+bool ConstantRange::isEmptySet() const {
+  return Lower == Upper && Lower == APInt::getMinValue(getBitWidth());
+}
+
+/// isWrappedSet - Return true if this set wraps around the top of the range,
+/// for example: [100, 8)
+///
+bool ConstantRange::isWrappedSet(bool isSigned) const {
+  if (isSigned)
+    return Lower.sgt(Upper);
+  return Lower.ugt(Upper);
+}
+
+/// getSetSize - Return the number of elements in this set.
+///
+APInt ConstantRange::getSetSize() const {
+  if (isEmptySet()) 
+    return APInt(getBitWidth(), 0);
+  if (getBitWidth() == 1) {
+    if (Lower != Upper)  // One of T or F in the set...
+      return APInt(2, 1);
+    return APInt(2, 2);      // Must be full set...
+  }
+
+  // Simply subtract the bounds...
+  return Upper - Lower;
+}
+
+/// contains - Return true if the specified value is in the set.
+///
+bool ConstantRange::contains(const APInt &V, bool isSigned) const {
+  if (Lower == Upper) {
+    if (isFullSet()) 
+      return true;
+    return false;
+  }
+
+  if (!isWrappedSet(isSigned))
+    if (isSigned)
+      return Lower.sle(V) && V.slt(Upper);
+    else
+      return Lower.ule(V) && V.ult(Upper);
+  if (isSigned)
+    return Lower.sle(V) || V.slt(Upper);
+  else
+    return Lower.ule(V) || V.ult(Upper);
+}
+
+/// subtract - Subtract the specified constant from the endpoints of this
+/// constant range.
+ConstantRange ConstantRange::subtract(const APInt &Val) const {
+  assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width");
+  // If the set is empty or full, don't modify the endpoints.
+  if (Lower == Upper) 
+    return *this;
+  return ConstantRange(Lower - Val, Upper - Val);
+}
+
+
+// intersect1Wrapped - This helper function is used to intersect two ranges when
+// it is known that LHS is wrapped and RHS isn't.
+//
+ConstantRange 
+ConstantRange::intersect1Wrapped(const ConstantRange &LHS,
+                                 const ConstantRange &RHS, bool isSigned) {
+  assert(LHS.isWrappedSet(isSigned) && !RHS.isWrappedSet(isSigned));
+
+  // Check to see if we overlap on the Left side of RHS...
+  //
+  bool LT = (isSigned ? RHS.Lower.slt(LHS.Upper) : RHS.Lower.ult(LHS.Upper));
+  bool GT = (isSigned ? RHS.Upper.sgt(LHS.Lower) : RHS.Upper.ugt(LHS.Lower));
+  if (LT) {
+    // We do overlap on the left side of RHS, see if we overlap on the right of
+    // RHS...
+    if (GT) {
+      // Ok, the result overlaps on both the left and right sides.  See if the
+      // resultant interval will be smaller if we wrap or not...
+      //
+      if (LHS.getSetSize().ult(RHS.getSetSize()))
+        return LHS;
+      else
+        return RHS;
+
+    } else {
+      // No overlap on the right, just on the left.
+      return ConstantRange(RHS.Lower, LHS.Upper);
+    }
+  } else {
+    // We don't overlap on the left side of RHS, see if we overlap on the right
+    // of RHS...
+    if (GT) {
+      // Simple overlap...
+      return ConstantRange(LHS.Lower, RHS.Upper);
+    } else {
+      // No overlap...
+      return ConstantRange(LHS.getBitWidth(), false);
+    }
+  }
+}
+
+/// intersectWith - Return the range that results from the intersection of this
+/// range with another range.
+///
+ConstantRange ConstantRange::intersectWith(const ConstantRange &CR,
+                                           bool isSigned) const {
+  assert(getBitWidth() == CR.getBitWidth() && 
+         "ConstantRange types don't agree!");
+  // Handle common special cases
+  if (isEmptySet() || CR.isFullSet())  
+    return *this;
+  if (isFullSet()  || CR.isEmptySet()) 
+    return CR;
+
+  if (!isWrappedSet(isSigned)) {
+    if (!CR.isWrappedSet(isSigned)) {
+      using namespace APIntOps;
+      APInt L = isSigned ? smax(Lower, CR.Lower) : umax(Lower, CR.Lower);
+      APInt U = isSigned ? smin(Upper, CR.Upper) : umin(Upper, CR.Upper);
+
+      if (isSigned ? L.slt(U) : L.ult(U)) // If range isn't empty...
+        return ConstantRange(L, U);
+      else
+        return ConstantRange(getBitWidth(), false);// Otherwise, empty set
+    } else
+      return intersect1Wrapped(CR, *this, isSigned);
+  } else {   // We know "this" is wrapped...
+    if (!CR.isWrappedSet(isSigned))
+      return intersect1Wrapped(*this, CR, isSigned);
+    else {
+      // Both ranges are wrapped...
+      using namespace APIntOps;
+      APInt L = isSigned ? smax(Lower, CR.Lower) : umax(Lower, CR.Lower);
+      APInt U = isSigned ? smin(Upper, CR.Upper) : umin(Upper, CR.Upper);
+      return ConstantRange(L, U);
+    }
+  }
+  return *this;
+}
+
+/// 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 [3,
+/// 15), which includes 9, 10, and 11, which were not included in either set
+/// before.
+///
+ConstantRange ConstantRange::unionWith(const ConstantRange &CR,
+                                       bool isSigned) const {
+  assert(getBitWidth() == CR.getBitWidth() && 
+         "ConstantRange types don't agree!");
+
+  assert(0 && "Range union not implemented yet!");
+
+  return *this;
+}
+
+/// zeroExtend - Return a new range in the specified integer type, which must
+/// be strictly larger than the current type.  The returned range will
+/// correspond to the possible range of values as if the source range had been
+/// zero extended.
+ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
+  unsigned SrcTySize = getBitWidth();
+  assert(SrcTySize < DstTySize && "Not a value extension");
+  if (isFullSet())
+    // Change a source full set into [0, 1 << 8*numbytes)
+    return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize));
+
+  APInt L = Lower; L.zext(DstTySize);
+  APInt U = Upper; U.zext(DstTySize);
+  return ConstantRange(L, U);
+}
+
+/// truncate - Return a new range in the specified integer type, which must be
+/// strictly smaller than the current type.  The returned range will
+/// correspond to the possible range of values as if the source range had been
+/// truncated to the specified type.
+ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
+  unsigned SrcTySize = getBitWidth();
+  assert(SrcTySize > DstTySize && "Not a value truncation");
+  APInt Size = APInt::getMaxValue(DstTySize).zext(SrcTySize);
+  if (isFullSet() || getSetSize().ugt(Size))
+    return ConstantRange(DstTySize);
+
+  APInt L = Lower; L.trunc(DstTySize);
+  APInt U = Upper; U.trunc(DstTySize);
+  return ConstantRange(L, U);
+}
+
+/// print - Print out the bounds to a stream...
+///
+void ConstantRange::print(std::ostream &OS) const {
+  OS << "[" << Lower.toStringSigned(10) << "," 
+            << Upper.toStringSigned(10) << " )";
+}
+
+/// dump - Allow printing from a debugger easily...
+///
+void ConstantRange::dump() const {
+  print(cerr);
+}