From b3b0c44ca3f1b87c719f782f09dd0331dbb1a351 Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Mon, 8 Jul 2013 18:04:14 +0200
Subject: Make information about use of jump table available via system_info
 BIF

erlang:system_info(beam_jump_table)
---
 erts/emulator/beam/beam_emu.c     | 9 +++++++++
 erts/emulator/beam/erl_bif_info.c | 3 +++
 erts/emulator/beam/global.h       | 2 ++
 3 files changed, 14 insertions(+)

(limited to 'erts/emulator')

diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index 5781009f58..da36c4437e 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -6256,3 +6256,12 @@ erts_current_reductions(Process *current, Process *p)
     }
 }
 
+int
+erts_beam_jump_table(void)
+{
+#if defined(NO_JUMP_TABLE)
+    return 0;
+#else
+    return 1;
+#endif
+}
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index b1dc62b4fd..e4fbd21c0e 100755
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -2583,6 +2583,9 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
     else if (ERTS_IS_ATOM_STR("emu_args", BIF_ARG_1)) {
 	BIF_RET(erts_get_emu_args(BIF_P));
     }
+    else if (ERTS_IS_ATOM_STR("beam_jump_table", BIF_ARG_1)) {
+	BIF_RET(erts_beam_jump_table() ? am_true : am_false);
+    }
     else if (ERTS_IS_ATOM_STR("dynamic_trace", BIF_ARG_1)) {
 #if defined(USE_DTRACE)
 	DECL_AM(dtrace);
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 25aedc91c6..e5807b5ce6 100755
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -1042,6 +1042,8 @@ extern erts_driver_t vanilla_driver;
 extern erts_driver_t spawn_driver;
 extern erts_driver_t fd_driver;
 
+int erts_beam_jump_table(void);
+
 /* Should maybe be placed in erl_message.h, but then we get an include mess. */
 ERTS_GLB_INLINE Eterm *
 erts_alloc_message_heap_state(Uint size,
-- 
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