1 files changed, 24 insertions, 10 deletions

diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index f940955a745..f1826c02979 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -272,6 +272,22 @@ APInt ConstantRange::getSetSize() const {
   return (Upper - Lower).zext(getBitWidth()+1);
 }
 
+/// isSizeStrictlySmallerThanOf - Compare set size of this range with the range
+/// CR.
+/// This function is faster than comparing results of getSetSize for the two
+/// ranges, because we don't need to extend bitwidth of APInts we're operating
+/// with.
+///
+bool
+ConstantRange::isSizeStrictlySmallerThanOf(const ConstantRange &Other) const {
+  assert(getBitWidth() == Other.getBitWidth());
+  if (isFullSet())
+    return false;
+  if (Other.isFullSet())
+    return true;
+  return (Upper - Lower).ult(Other.Upper - Other.Lower);
+}
+
 /// getUnsignedMax - Return the largest unsigned value contained in the
 /// ConstantRange.
 ///
@@ -414,7 +430,7 @@ ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
       if (CR.Upper.ule(Lower))
         return ConstantRange(CR.Lower, Upper);
 
-      if (getSetSize().ult(CR.getSetSize()))
+      if (isSizeStrictlySmallerThanOf(CR))
         return *this;
       return CR;
     }
@@ -429,7 +445,7 @@ ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
 
   if (CR.Upper.ult(Upper)) {
     if (CR.Lower.ult(Upper)) {
-      if (getSetSize().ult(CR.getSetSize()))
+      if (isSizeStrictlySmallerThanOf(CR))
         return *this;
       return CR;
     }
@@ -445,7 +461,7 @@ ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
 
     return ConstantRange(CR.Lower, Upper);
   }
-  if (getSetSize().ult(CR.getSetSize()))
+  if (isSizeStrictlySmallerThanOf(CR))
     return *this;
   return CR;
 }
@@ -739,17 +755,16 @@ ConstantRange::add(const ConstantRange &Other) const {
   if (isFullSet() || Other.isFullSet())
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
-  APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
   APInt NewLower = getLower() + Other.getLower();
   APInt NewUpper = getUpper() + Other.getUpper() - 1;
   if (NewLower == NewUpper)
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
   ConstantRange X = ConstantRange(NewLower, NewUpper);
-  if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
+  if (X.isSizeStrictlySmallerThanOf(*this) ||
+      X.isSizeStrictlySmallerThanOf(Other))
     // We've wrapped, therefore, full set.
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
-
   return X;
 }
 
@@ -773,17 +788,16 @@ ConstantRange::sub(const ConstantRange &Other) const {
   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))
+  if (X.isSizeStrictlySmallerThanOf(*this) ||
+      X.isSizeStrictlySmallerThanOf(Other))
     // We've wrapped, therefore, full set.
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
-
   return X;
 }
 
@@ -837,7 +851,7 @@ ConstantRange::multiply(const ConstantRange &Other) const {
   ConstantRange Result_sext(std::min(L, Compare), std::max(L, Compare) + 1);
   ConstantRange SR = Result_sext.truncate(getBitWidth());
 
-  return UR.getSetSize().ult(SR.getSetSize()) ? UR : SR;
+  return UR.isSizeStrictlySmallerThanOf(SR) ? UR : SR;
 }
 
 ConstantRange