[ConstantRange] Handle wrapping range in binaryNot()

We don't need any special handling for wrapping ranges (or empty
ranges for that matter). The sub() call will already compute a
correct and precise range.

We only need to adjust the test expectation: We're now computing
an optimal result, rather than an unsigned envelope.

Author: nikic

llvm/lib/IR/ConstantRange.cpp

@@ -1256,12 +1256,6 @@ ConstantRange ConstantRange::srem(const ConstantRange &RHS) const {
 }
 
 ConstantRange ConstantRange::binaryNot() const {
-  if (isEmptySet())
-    return getEmpty();
-
-  if (isWrappedSet())
-    return getFull();
-
   return ConstantRange(APInt::getAllOnesValue(getBitWidth())).sub(*this);
 }
 

llvm/unittests/IR/ConstantRangeTest.cpp

@@ -2388,26 +2388,24 @@ TEST_F(ConstantRangeTest, binaryXor) {
 }
 
 TEST_F(ConstantRangeTest, binaryNot) {
-  // TODO: Improve binaryNot() implementation to remove the need for
-  // PreferSmallestUnsigned.
   TestUnaryOpExhaustive(
       [](const ConstantRange &CR) { return CR.binaryNot(); },
       [](const APInt &N) { return ~N; },
-      PreferSmallestUnsigned);
+      PreferSmallest);
   TestUnaryOpExhaustive(
       [](const ConstantRange &CR) {
         return CR.binaryXor(
             ConstantRange(APInt::getAllOnesValue(CR.getBitWidth())));
       },
       [](const APInt &N) { return ~N; },
-      PreferSmallestUnsigned);
+      PreferSmallest);
   TestUnaryOpExhaustive(
       [](const ConstantRange &CR) {
         return ConstantRange(APInt::getAllOnesValue(CR.getBitWidth()))
             .binaryXor(CR);
       },
       [](const APInt &N) { return ~N; },
-      PreferSmallestUnsigned);
+      PreferSmallest);
 }
 
 }  // anonymous namespace