X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FSupport%2FConstantRange.cpp;h=720ef36c4640f4812c35c65faf390c925d238329;hb=c56e3f0cdde9b5e3f8222ece7b5968ae9961955e;hp=e427f820c44632988ae06fdca171018223f5d726;hpb=4459145c2ccb5d063841a5d8c76b8b8ac9adaf2f;p=oota-llvm.git

diff --git a/lib/Support/ConstantRange.cpp b/lib/Support/ConstantRange.cpp
index e427f820c44..720ef36c464 100644
--- a/lib/Support/ConstantRange.cpp
+++ b/lib/Support/ConstantRange.cpp
@@ -21,9 +21,10 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/InstrTypes.h"
 #include "llvm/Support/ConstantRange.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/Instructions.h"
 using namespace llvm;
 
 /// Initialize a full (the default) or empty set for the specified type.
@@ -37,7 +38,7 @@ ConstantRange::ConstantRange(uint32_t BitWidth, bool Full) {
 
 /// Initialize a range to hold the single specified value.
 ///
-ConstantRange::ConstantRange(const APInt & V) : Lower(V), Upper(V + 1) {}
+ConstantRange::ConstantRange(const APInt &V) : Lower(V), Upper(V + 1) {}
 
 ConstantRange::ConstantRange(const APInt &L, const APInt &U) :
   Lower(L), Upper(U) {
@@ -49,43 +50,61 @@ ConstantRange::ConstantRange(const APInt &L, const APInt &U) :
 
 ConstantRange ConstantRange::makeICmpRegion(unsigned Pred,
                                             const ConstantRange &CR) {
+  if (CR.isEmptySet())
+    return CR;
+
   uint32_t W = CR.getBitWidth();
   switch (Pred) {
-    default: assert(!"Invalid ICmp predicate to makeICmpRegion()");
-    case ICmpInst::ICMP_EQ:
+    default: llvm_unreachable("Invalid ICmp predicate to makeICmpRegion()");
+    case CmpInst::ICMP_EQ:
       return CR;
-    case ICmpInst::ICMP_NE:
+    case CmpInst::ICMP_NE:
       if (CR.isSingleElement())
         return ConstantRange(CR.getUpper(), CR.getLower());
       return ConstantRange(W);
-    case ICmpInst::ICMP_ULT:
-      return ConstantRange(APInt::getMinValue(W), CR.getUnsignedMax());
-    case ICmpInst::ICMP_SLT:
-      return ConstantRange(APInt::getSignedMinValue(W), CR.getSignedMax());
-    case ICmpInst::ICMP_ULE: {
+    case CmpInst::ICMP_ULT: {
+      APInt UMax(CR.getUnsignedMax());
+      if (UMax.isMinValue())
+        return ConstantRange(W, /* empty */ false);
+      return ConstantRange(APInt::getMinValue(W), UMax);
+    }
+    case CmpInst::ICMP_SLT: {
+      APInt SMax(CR.getSignedMax());
+      if (SMax.isMinSignedValue())
+        return ConstantRange(W, /* empty */ false);
+      return ConstantRange(APInt::getSignedMinValue(W), SMax);
+    }
+    case CmpInst::ICMP_ULE: {
       APInt UMax(CR.getUnsignedMax());
       if (UMax.isMaxValue())
         return ConstantRange(W);
       return ConstantRange(APInt::getMinValue(W), UMax + 1);
     }
-    case ICmpInst::ICMP_SLE: {
+    case CmpInst::ICMP_SLE: {
       APInt SMax(CR.getSignedMax());
-      if (SMax.isMaxSignedValue() || (SMax+1).isMaxSignedValue())
+      if (SMax.isMaxSignedValue())
         return ConstantRange(W);
       return ConstantRange(APInt::getSignedMinValue(W), SMax + 1);
     }
-    case ICmpInst::ICMP_UGT:
-      return ConstantRange(CR.getUnsignedMin() + 1, APInt::getNullValue(W));
-    case ICmpInst::ICMP_SGT:
-      return ConstantRange(CR.getSignedMin() + 1,
-                           APInt::getSignedMinValue(W));
-    case ICmpInst::ICMP_UGE: {
+    case CmpInst::ICMP_UGT: {
+      APInt UMin(CR.getUnsignedMin());
+      if (UMin.isMaxValue())
+        return ConstantRange(W, /* empty */ false);
+      return ConstantRange(UMin + 1, APInt::getNullValue(W));
+    }
+    case CmpInst::ICMP_SGT: {
+      APInt SMin(CR.getSignedMin());
+      if (SMin.isMaxSignedValue())
+        return ConstantRange(W, /* empty */ false);
+      return ConstantRange(SMin + 1, APInt::getSignedMinValue(W));
+    }
+    case CmpInst::ICMP_UGE: {
       APInt UMin(CR.getUnsignedMin());
       if (UMin.isMinValue())
         return ConstantRange(W);
       return ConstantRange(UMin, APInt::getNullValue(W));
     }
-    case ICmpInst::ICMP_SGE: {
+    case CmpInst::ICMP_SGE: {
       APInt SMin(CR.getSignedMin());
       if (SMin.isMinSignedValue())
         return ConstantRange(W);
@@ -113,19 +132,28 @@ bool ConstantRange::isWrappedSet() const {
   return Lower.ugt(Upper);
 }
 
+/// isSignWrappedSet - Return true if this set wraps around the INT_MIN of
+/// its bitwidth, for example: i8 [120, 140).
+///
+bool ConstantRange::isSignWrappedSet() const {
+  return contains(APInt::getSignedMaxValue(getBitWidth())) &&
+         contains(APInt::getSignedMinValue(getBitWidth()));
+}
+
 /// 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...
+  if (isEmptySet())
+    return APInt(getBitWidth()+1, 0);
+
+  if (isFullSet()) {
+    APInt Size(getBitWidth()+1, 0);
+    Size.setBit(getBitWidth());
+    return Size;
   }
 
-  // Simply subtract the bounds...
-  return Upper - Lower;
+  // This is also correct for wrapped sets.
+  return (Upper - Lower).zext(getBitWidth()+1);
 }
 
 /// getUnsignedMax - Return the largest unsigned value contained in the
@@ -134,8 +162,7 @@ APInt ConstantRange::getSetSize() const {
 APInt ConstantRange::getUnsignedMax() const {
   if (isFullSet() || isWrappedSet())
     return APInt::getMaxValue(getBitWidth());
-  else
-    return getUpper() - 1;
+  return getUpper() - 1;
 }
 
 /// getUnsignedMin - Return the smallest unsigned value contained in the
@@ -144,8 +171,7 @@ APInt ConstantRange::getUnsignedMax() const {
 APInt ConstantRange::getUnsignedMin() const {
   if (isFullSet() || (isWrappedSet() && getUpper() != 0))
     return APInt::getMinValue(getBitWidth());
-  else
-    return getLower();
+  return getLower();
 }
 
 /// getSignedMax - Return the largest signed value contained in the
@@ -156,14 +182,11 @@ APInt ConstantRange::getSignedMax() const {
   if (!isWrappedSet()) {
     if (getLower().sle(getUpper() - 1))
       return getUpper() - 1;
-    else
-      return SignedMax;
-  } else {
-    if (getLower().isNegative() == getUpper().isNegative())
-      return SignedMax;
-    else
-      return getUpper() - 1;
+    return SignedMax;
   }
+  if (getLower().isNegative() == getUpper().isNegative())
+    return SignedMax;
+  return getUpper() - 1;
 }
 
 /// getSignedMin - Return the smallest signed value contained in the
@@ -174,18 +197,13 @@ APInt ConstantRange::getSignedMin() const {
   if (!isWrappedSet()) {
     if (getLower().sle(getUpper() - 1))
       return getLower();
-    else
+    return SignedMin;
+  }
+  if ((getUpper() - 1).slt(getLower())) {
+    if (getUpper() != SignedMin)
       return SignedMin;
-  } else {
-    if ((getUpper() - 1).slt(getLower())) {
-      if (getUpper() != SignedMin)
-        return SignedMin;
-      else
-        return getLower();
-    } else {
-      return getLower();
-    }
   }
+  return getLower();
 }
 
 /// contains - Return true if the specified value is in the set.
@@ -196,19 +214,16 @@ bool ConstantRange::contains(const APInt &V) const {
 
   if (!isWrappedSet())
     return Lower.ule(V) && V.ult(Upper);
-  else
-    return Lower.ule(V) || V.ult(Upper);
+  return Lower.ule(V) || V.ult(Upper);
 }
 
 /// contains - Return true if the argument is a subset of this range.
-/// Two equal set contain each other. The empty set is considered to be
-/// contained by all other sets.
+/// Two equal sets contain each other. The empty set contained by all other
+/// sets.
 ///
 bool ConstantRange::contains(const ConstantRange &Other) const {
-  if (isFullSet()) return true;
-  if (Other.isFullSet()) return false;
-  if (Other.isEmptySet()) return true;
-  if (isEmptySet()) return false;
+  if (isFullSet() || Other.isEmptySet()) return true;
+  if (isEmptySet() || Other.isFullSet()) return false;
 
   if (!isWrappedSet()) {
     if (Other.isWrappedSet())
@@ -234,44 +249,10 @@ ConstantRange ConstantRange::subtract(const APInt &Val) const {
   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) {
-  assert(LHS.isWrappedSet() && !RHS.isWrappedSet());
-
-  // Check to see if we overlap on the Left side of RHS...
-  //
-  if (RHS.Lower.ult(LHS.Upper)) {
-    // We do overlap on the left side of RHS, see if we overlap on the right of
-    // RHS...
-    if (RHS.Upper.ugt(LHS.Lower)) {
-      // 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 (RHS.Upper.ugt(LHS.Lower)) {
-      // Simple overlap...
-      return ConstantRange(LHS.Lower, RHS.Upper);
-    } else {
-      // No overlap...
-      return ConstantRange(LHS.getBitWidth(), false);
-    }
-  }
+/// \brief Subtract the specified range from this range (aka relative complement
+/// of the sets).
+ConstantRange ConstantRange::difference(const ConstantRange &CR) const {
+  return intersectWith(CR.inverse());
 }
 
 /// intersectWith - Return the range that results from the intersection of this
@@ -299,15 +280,14 @@ ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
         return ConstantRange(CR.Lower, Upper);
 
       return CR;
-    } else {
-      if (Upper.ult(CR.Upper))
-        return *this;
+    }
+    if (Upper.ult(CR.Upper))
+      return *this;
 
-      if (Lower.ult(CR.Upper))
-        return ConstantRange(Lower, CR.Upper);
+    if (Lower.ult(CR.Upper))
+      return ConstantRange(Lower, CR.Upper);
 
-      return ConstantRange(getBitWidth(), false);
-    }
+    return ConstantRange(getBitWidth(), false);
   }
 
   if (isWrappedSet() && !CR.isWrappedSet()) {
@@ -315,14 +295,14 @@ ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
       if (CR.Upper.ult(Upper))
         return CR;
 
-      if (CR.Upper.ult(Lower))
+      if (CR.Upper.ule(Lower))
         return ConstantRange(CR.Lower, Upper);
 
       if (getSetSize().ult(CR.getSetSize()))
         return *this;
-      else
-        return CR;
-    } else if (CR.Lower.ult(Lower)) {
+      return CR;
+    }
+    if (CR.Lower.ult(Lower)) {
       if (CR.Upper.ule(Lower))
         return ConstantRange(getBitWidth(), false);
 
@@ -335,15 +315,15 @@ ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
     if (CR.Lower.ult(Upper)) {
       if (getSetSize().ult(CR.getSetSize()))
         return *this;
-      else
-        return CR;
+      return CR;
     }
 
     if (CR.Lower.ult(Lower))
       return ConstantRange(Lower, CR.Upper);
 
     return CR;
-  } else if (CR.Upper.ult(Lower)) {
+  }
+  if (CR.Upper.ule(Lower)) {
     if (CR.Lower.ult(Lower))
       return *this;
 
@@ -351,8 +331,7 @@ ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
   }
   if (getSetSize().ult(CR.getSetSize()))
     return *this;
-  else
-    return CR;
+  return CR;
 }
 
 
@@ -377,8 +356,7 @@ ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
       APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
       if (d1.ult(d2))
         return ConstantRange(Lower, CR.Upper);
-      else
-        return ConstantRange(CR.Lower, Upper);
+      return ConstantRange(CR.Lower, Upper);
     }
 
     APInt L = Lower, U = Upper;
@@ -411,8 +389,7 @@ ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
       APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
       if (d1.ult(d2))
         return ConstantRange(Lower, CR.Upper);
-      else
-        return ConstantRange(CR.Lower, Upper);
+      return ConstantRange(CR.Lower, Upper);
     }
 
     // ----U     L----- : this
@@ -422,13 +399,11 @@ ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
 
     // ------U    L---- : this
     //    L-----U       : CR
-    if (CR.Lower.ult(Upper) && CR.Upper.ult(Lower))
-      return ConstantRange(Lower, CR.Upper);
+    assert(CR.Lower.ult(Upper) && CR.Upper.ult(Lower) &&
+           "ConstantRange::unionWith missed a case with one range wrapped");
+    return ConstantRange(Lower, CR.Upper);
   }
 
-  assert(isWrappedSet() && CR.isWrappedSet() &&
-         "ConstantRange::unionWith missed wrapped union unwrapped case");
-
   // ------U    L----  and  ------U    L---- : this
   // -U  L-----------  and  ------------U  L : CR
   if (CR.Lower.ule(Upper) || Lower.ule(CR.Upper))
@@ -448,15 +423,19 @@ ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
 /// correspond to the possible range of values as if the source range had been
 /// zero extended.
 ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
+  if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
+
   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));
+  if (isFullSet() || isWrappedSet()) {
+    // Change into [0, 1 << src bit width)
+    APInt LowerExt(DstTySize, 0);
+    if (!Upper) // special case: [X, 0) -- not really wrapping around
+      LowerExt = Lower.zext(DstTySize);
+    return ConstantRange(LowerExt, APInt(DstTySize, 1).shl(SrcTySize));
+  }
 
-  APInt L = Lower; L.zext(DstTySize);
-  APInt U = Upper; U.zext(DstTySize);
-  return ConstantRange(L, U);
+  return ConstantRange(Lower.zext(DstTySize), Upper.zext(DstTySize));
 }
 
 /// signExtend - Return a new range in the specified integer type, which must
@@ -464,16 +443,16 @@ ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
 /// correspond to the possible range of values as if the source range had been
 /// sign extended.
 ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
+  if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
+
   unsigned SrcTySize = getBitWidth();
   assert(SrcTySize < DstTySize && "Not a value extension");
-  if (isFullSet()) {
+  if (isFullSet() || isSignWrappedSet()) {
     return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
                          APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
   }
 
-  APInt L = Lower; L.sext(DstTySize);
-  APInt U = Upper; U.sext(DstTySize);
-  return ConstantRange(L, U);
+  return ConstantRange(Lower.sext(DstTySize), Upper.sext(DstTySize));
 }
 
 /// truncate - Return a new range in the specified integer type, which must be
@@ -481,15 +460,54 @@ ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
 /// 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::getLowBitsSet(SrcTySize, DstTySize));
-  if (isFullSet() || getSetSize().ugt(Size))
-    return ConstantRange(DstTySize);
+  assert(getBitWidth() > DstTySize && "Not a value truncation");
+  if (isEmptySet())
+    return ConstantRange(DstTySize, /*isFullSet=*/false);
+  if (isFullSet())
+    return ConstantRange(DstTySize, /*isFullSet=*/true);
+
+  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;
+  }
 
-  APInt L = Lower; L.trunc(DstTySize);
-  APInt U = Upper; U.trunc(DstTySize);
-  return ConstantRange(L, U);
+  // 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);
 }
 
 /// zextOrTrunc - make this range have the bit width given by \p DstTySize. The
@@ -498,10 +516,9 @@ ConstantRange ConstantRange::zextOrTrunc(uint32_t DstTySize) const {
   unsigned SrcTySize = getBitWidth();
   if (SrcTySize > DstTySize)
     return truncate(DstTySize);
-  else if (SrcTySize < DstTySize)
+  if (SrcTySize < DstTySize)
     return zeroExtend(DstTySize);
-  else
-    return *this;
+  return *this;
 }
 
 /// sextOrTrunc - make this range have the bit width given by \p DstTySize. The
@@ -510,10 +527,9 @@ ConstantRange ConstantRange::sextOrTrunc(uint32_t DstTySize) const {
   unsigned SrcTySize = getBitWidth();
   if (SrcTySize > DstTySize)
     return truncate(DstTySize);
-  else if (SrcTySize < DstTySize)
+  if (SrcTySize < DstTySize)
     return signExtend(DstTySize);
-  else
-    return *this;
+  return *this;
 }
 
 ConstantRange
@@ -538,12 +554,36 @@ ConstantRange::add(const ConstantRange &Other) const {
 }
 
 ConstantRange
-ConstantRange::multiply(const ConstantRange &Other) const {
+ConstantRange::sub(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())
     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
   if (isFullSet() || Other.isFullSet())
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
+  APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
+  APInt NewLower = getLower() - Other.getUpper() + 1;
+  APInt NewUpper = getUpper() - Other.getLower();
+  if (NewLower == NewUpper)
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+
+  ConstantRange X = ConstantRange(NewLower, NewUpper);
+  if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
+    // We've wrapped, therefore, full set.
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+
+  return X;
+}
+
+ConstantRange
+ConstantRange::multiply(const ConstantRange &Other) const {
+  // TODO: If either operand is a single element and the multiply is known to
+  // be non-wrapping, round the result min and max value to the appropriate
+  // multiple of that element. If wrapping is possible, at least adjust the
+  // range according to the greatest power-of-two factor of the single element.
+
+  if (isEmptySet() || Other.isEmptySet())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
+
   APInt this_min = getUnsignedMin().zext(getBitWidth() * 2);
   APInt this_max = getUnsignedMax().zext(getBitWidth() * 2);
   APInt Other_min = Other.getUnsignedMin().zext(getBitWidth() * 2);
@@ -610,52 +650,82 @@ ConstantRange::udiv(const ConstantRange &RHS) const {
 }
 
 ConstantRange
-ConstantRange::shl(const ConstantRange &Amount) const {
-  if (isEmptySet())
-    return *this;
+ConstantRange::binaryAnd(const ConstantRange &Other) const {
+  if (isEmptySet() || Other.isEmptySet())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 
-  APInt min = getUnsignedMin() << Amount.getUnsignedMin();
-  APInt max = getUnsignedMax() << Amount.getUnsignedMax();
+  // TODO: replace this with something less conservative
+
+  APInt umin = APIntOps::umin(Other.getUnsignedMax(), getUnsignedMax());
+  if (umin.isAllOnesValue())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+  return ConstantRange(APInt::getNullValue(getBitWidth()), umin + 1);
+}
+
+ConstantRange
+ConstantRange::binaryOr(const ConstantRange &Other) const {
+  if (isEmptySet() || Other.isEmptySet())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
+
+  // TODO: replace this with something less conservative
+
+  APInt umax = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
+  if (umax.isMinValue())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+  return ConstantRange(umax, APInt::getNullValue(getBitWidth()));
+}
+
+ConstantRange
+ConstantRange::shl(const ConstantRange &Other) const {
+  if (isEmptySet() || Other.isEmptySet())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
+
+  APInt min = getUnsignedMin().shl(Other.getUnsignedMin());
+  APInt max = getUnsignedMax().shl(Other.getUnsignedMax());
 
   // there's no overflow!
   APInt Zeros(getBitWidth(), getUnsignedMax().countLeadingZeros());
-  if (Zeros.uge(Amount.getUnsignedMax()))
-    return ConstantRange(min, max);
+  if (Zeros.ugt(Other.getUnsignedMax()))
+    return ConstantRange(min, max + 1);
 
   // FIXME: implement the other tricky cases
-  return ConstantRange(getBitWidth());
+  return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 }
 
 ConstantRange
-ConstantRange::ashr(const ConstantRange &Amount) const {
-  if (isEmptySet())
-    return *this;
+ConstantRange::lshr(const ConstantRange &Other) const {
+  if (isEmptySet() || Other.isEmptySet())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
+  
+  APInt max = getUnsignedMax().lshr(Other.getUnsignedMin());
+  APInt min = getUnsignedMin().lshr(Other.getUnsignedMax());
+  if (min == max + 1)
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
-  APInt min = getUnsignedMax().ashr(Amount.getUnsignedMin());
-  APInt max = getUnsignedMin().ashr(Amount.getUnsignedMax());
-  return ConstantRange(min, max);
+  return ConstantRange(min, max + 1);
 }
 
-ConstantRange
-ConstantRange::lshr(const ConstantRange &Amount) const {
+ConstantRange ConstantRange::inverse() const {
+  if (isFullSet())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/false);
   if (isEmptySet())
-    return *this;
-  
-  APInt min = getUnsignedMax().lshr(Amount.getUnsignedMin());
-  APInt max = getUnsignedMin().lshr(Amount.getUnsignedMax());
-  return ConstantRange(min, max);
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+  return ConstantRange(Upper, Lower);
 }
 
 /// print - Print out the bounds to a stream...
 ///
 void ConstantRange::print(raw_ostream &OS) const {
-  OS << "[" << Lower << "," << Upper << ")";
+  if (isFullSet())
+    OS << "full-set";
+  else if (isEmptySet())
+    OS << "empty-set";
+  else
+    OS << "[" << Lower << "," << Upper << ")";
 }
 
 /// dump - Allow printing from a debugger easily...
 ///
 void ConstantRange::dump() const {
-  print(errs());
+  print(dbgs());
 }
-
-