note LLVM in fixme

src/librustc_mir/transform/const_prop.rs

@@ -1112,7 +1112,7 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
             }
             TerminatorKind::SwitchInt { ref mut discr, .. } => {
                 // FIXME: This is currently redundant with `visit_operand`, but sadly
-                // always visiting operands currently causes a perf regression, so
+                // always visiting operands currently causes a perf regression in LLVM codegen, so
                 // `visit_operand` currently only runs for propagates places for `mir_opt_level=3`.
                 self.propagate_operand(discr, location)
             }