erts: Keep track of which NIF a scheduler is executing

This may be of interest in crash dumps and allows the upcoming
allocation tagging feature to track allocations on a per-NIF basis.

Note that this is only updated when user code calls a NIF; it's not
altered when the emulator calls NIFs during code upgrades or
tracing.

1 files changed, 8 insertions, 0 deletions

diff --git a/erts/emulator/beam/bif_instrs.tab b/erts/emulator/beam/bif_instrs.tab
index 0932b8b985..0f074280db 100644
--- a/erts/emulator/beam/bif_instrs.tab
+++ b/erts/emulator/beam/bif_instrs.tab
@@ -432,9 +432,17 @@ nif_bif.call_nif() {
         live_hf_end = c_p->mbuf;
         ERTS_CHK_MBUF_SZ(c_p);
         erts_pre_nif(&env, c_p, (struct erl_module_nif*)I[2], NULL);
+
+        ASSERT((c_p->scheduler_data)->current_nif == NULL);
+        (c_p->scheduler_data)->current_nif = &env;
+
         nif_bif_result = (*fp)(&env, bif_nif_arity, reg);
         if (env.exception_thrown)
             nif_bif_result = THE_NON_VALUE;
+
+        ASSERT((c_p->scheduler_data)->current_nif == &env);
+        (c_p->scheduler_data)->current_nif = NULL;
+
         erts_post_nif(&env);
         ERTS_CHK_MBUF_SZ(c_p);