do not set the attributes quite as often

compiler/rustc_codegen_llvm/src/abi.rs

@@ -663,7 +663,12 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
         }
 
         // If the call site has an associated instance, compute extra attributes based on that.
-        if let Some(instance) = instance {
+        // However, only do that for calls to imported functions: all the others have these
+        // attributes applied already to the declaration, so we can save some work by not also
+        // applying them here (and this really shows in perf).
+        if let Some(instance) = instance
+            && bx.tcx.is_foreign_item(instance.def_id())
+        {
             llfn_attrs_from_instance(bx.cx, instance, None, |place, attrs| {
                 attributes::apply_to_callsite(callsite, place, attrs)
             });

tests/codegen/cffi/ffi-out-of-bounds-loads.rs

@@ -1,6 +1,6 @@
 //@ revisions: linux apple
 //@ min-llvm-version: 19
-//@ compile-flags: -Copt-level=0 -Cno-prepopulate-passes -Zlint-llvm-ir -Cllvm-args=-lint-abort-on-error
+//@ compile-flags: -Copt-level=0 -Cno-prepopulate-passes -Zlint-llvm-ir
 
 //@[linux] compile-flags: --target x86_64-unknown-linux-gnu
 //@[linux] needs-llvm-components: x86