[sledge] fix only-needed

Reviewed By: jberdine

Differential Revision: D15420742

fbshipit-source-id: 7332f849d

sledge/src/llair/dune.in

@@ -16,7 +16,7 @@ Jbuild_plugin.V1.send
  (name llair_)
  (public_name llair)
  %s
- (libraries ctypes ctypes.foreign llvm llvm.irreader llvm.analysis llvm.scalar_opts llvm.target %s))
+ (libraries ctypes ctypes.foreign llvm llvm.irreader llvm.analysis llvm.scalar_opts llvm.target llvm.ipo %s))
 |}
      (flags `lib deps)
      (libraries deps)

sledge/src/llair/frontend.ml

@@ -1335,6 +1335,7 @@ let xlate_function : x -> Llvm.llvalue -> Llair.func =
 let transform : Llvm.llmodule -> unit =
  fun llmodule ->
   let pm = Llvm.PassManager.create () in
+  Llvm_ipo.add_global_dce pm ;
   Llvm_scalar_opts.add_lower_atomic pm ;
   Llvm_scalar_opts.add_scalar_repl_aggregation pm ;
   Llvm_scalar_opts.add_scalarizer pm ;