diff --git a/flang/lib/Optimizer/Builder/PPCIntrinsicCall.cpp b/flang/lib/Optimizer/Builder/PPCIntrinsicCall.cpp
--- a/flang/lib/Optimizer/Builder/PPCIntrinsicCall.cpp
+++ b/flang/lib/Optimizer/Builder/PPCIntrinsicCall.cpp
@@ -614,7 +614,7 @@
       break;
     }
     default:
-      assert(false && "Invalid vector operation for generator");
+      llvm_unreachable("Invalid vector operation for generator");
     }
   } else if (vecTyInfo.isFloat()) {
     mlir::Value vargs[2];
@@ -631,12 +631,12 @@
       vargs[1] = argBases[0];
       break;
     default:
-      assert(false && "Invalid vector operation for generator");
+      llvm_unreachable("Invalid vector operation for generator");
     }
     auto callOp{builder.create<fir::CallOp>(loc, funcOp, vargs)};
     res = callOp.getResult(0);
   } else
-    assert(false && "invalid vector type");
+    llvm_unreachable("invalid vector type");
 
   return res;
 }