1 files changed, 4 insertions, 1 deletions
diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index 84eb0937765..a4f82a742dd 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -682,7 +682,10 @@ void MCAsmStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
       // We truncate our partial emission to fit within the bounds of the
       // emission domain.  This produces nicer output and silences potential
       // truncation warnings when round tripping through another assembler.
-      ValueToEmit &= ~0ULL >> (64 - EmissionSize * 8);
+      uint64_t Shift = 64 - EmissionSize * 8;
+      assert(Shift < std::numeric_limits<unsigned long long>::digits &&
+             "undefined behavior");
+      ValueToEmit &= ~0ULL >> Shift;
       EmitIntValue(ValueToEmit, EmissionSize);
       Emitted += EmissionSize;
     }