Ensure KnownBits passed to computeKnownBitsFromRangeMetadata has correct size

Signed-off-by: John Lu <[email protected]>

Author: LU-JOHN

llvm/lib/Analysis/ValueTracking.cpp

@@ -433,6 +433,8 @@ void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
     // The first CommonPrefixBits of all values in Range are equal.
     unsigned CommonPrefixBits =
         (Range.getUnsignedMax() ^ Range.getUnsignedMin()).countl_zero();
+    // BitWidth must equal the Ranges BitWidth for the correct number of high bits to be set.
+    assert(BitWidth == Lower->getBitWidth() );
     APInt Mask = APInt::getHighBitsSet(BitWidth, CommonPrefixBits);
     APInt UnsignedMax = Range.getUnsignedMax().zextOrTrunc(BitWidth);
     Known.One &= UnsignedMax & Mask;