[ValueTracking] Add APInt::setSignBit and use it to replace ORing with getSignBit...

llvm-svn: 298180

diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index 8e6c7bc..8d8c898 100644 (file)
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -1175,6 +1175,11 @@ public:
   /// Set the given bit to 1 whose position is given as "bitPosition".
   void setBit(unsigned bitPosition);
 
+  /// Set the sign bit to 1.
+  void setSignBit() {
+    setBit(BitWidth - 1);
+  }
+
   /// Set the bits from loBit (inclusive) to hiBit (exclusive) to 1.
   void setBits(unsigned loBit, unsigned hiBit) {
     assert(hiBit <= BitWidth && "hiBit out of range");

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index a3d4198..38d9c29 100644 (file)
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -321,11 +321,11 @@ static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1,
       // Adding two non-negative numbers, or subtracting a negative number from
       // a non-negative one, can't wrap into negative.
       if (LHSKnownZero.isNegative() && KnownZero2.isNegative())
-        KnownZero |= APInt::getSignBit(BitWidth);
+        KnownZero.setSignBit();
       // Adding two negative numbers, or subtracting a non-negative number from
       // a negative one, can't wrap into non-negative.
       else if (LHSKnownOne.isNegative() && KnownOne2.isNegative())
-        KnownOne |= APInt::getSignBit(BitWidth);
+        KnownOne.setSignBit();
     }
   }
 }
@@ -732,7 +732,7 @@ static void computeKnownBitsFromAssume(const Value *V, APInt &KnownZero,
 
       if (RHSKnownZero.isNegative()) {
         // We know that the sign bit is zero.
-        KnownZero |= APInt::getSignBit(BitWidth);
+        KnownZero.setSignBit();
       }
     // assume(v >_s c) where c is at least -1.
     } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
@@ -743,7 +743,7 @@ static void computeKnownBitsFromAssume(const Value *V, APInt &KnownZero,
 
       if (RHSKnownOne.isAllOnesValue() || RHSKnownZero.isNegative()) {
         // We know that the sign bit is zero.
-        KnownZero |= APInt::getSignBit(BitWidth);
+        KnownZero.setSignBit();
       }
     // assume(v <=_s c) where c is negative
     } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
@@ -754,7 +754,7 @@ static void computeKnownBitsFromAssume(const Value *V, APInt &KnownZero,
 
       if (RHSKnownOne.isNegative()) {
         // We know that the sign bit is one.
-        KnownOne |= APInt::getSignBit(BitWidth);
+        KnownOne.setSignBit();
       }
     // assume(v <_s c) where c is non-positive
     } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
@@ -765,7 +765,7 @@ static void computeKnownBitsFromAssume(const Value *V, APInt &KnownZero,
 
       if (RHSKnownZero.isAllOnesValue() || RHSKnownOne.isNegative()) {
         // We know that the sign bit is one.
-        KnownOne |= APInt::getSignBit(BitWidth);
+        KnownOne.setSignBit();
       }
     // assume(v <=_u c)
     } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&