Only enable no-plt when full relro is enabled

Author: GabrielMajeri

src/librustc_codegen_llvm/attributes.rs

@@ -20,7 +20,7 @@ use rustc::ty::layout::HasTyCtxt;
 use rustc::ty::query::Providers;
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_target::spec::PanicStrategy;
+use rustc_target::spec::{PanicStrategy, RelroLevel};
 
 use attributes;
 use llvm::{self, Attribute};
@@ -173,7 +173,12 @@ pub fn from_fn_attrs(
 
     set_frame_pointer_elimination(cx, llfn);
     set_probestack(cx, llfn);
-    Attribute::NonLazyBind.apply_llfn(Function, llfn);
+
+    // Only enable this optimization if full relro is also enabled.
+    // In this case, lazy binding was already unavailable, so nothing is lost.
+    if let RelroLevel::Full = cx.sess().target.target.options.relro_level {
+        Attribute::NonLazyBind.apply_llfn(Function, llfn);
+    }
 
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
         Attribute::Cold.apply_llfn(Function, llfn);