[APInt] Use SignExtend64 instead of reinventing it. NFC

llvm-svn: 300747

diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index b508c77..cdcb178 100644 (file)
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -1433,8 +1433,7 @@ public:
   /// int64_t. Otherwise an assertion will result.
   int64_t getSExtValue() const {
     if (isSingleWord())
-      return int64_t(VAL << (APINT_BITS_PER_WORD - BitWidth)) >>
-             (APINT_BITS_PER_WORD - BitWidth);
+      return SignExtend64(VAL, BitWidth);
     assert(getMinSignedBits() <= 64 && "Too many bits for int64_t");
     return int64_t(pVal[0]);
   }