File 2260-Add-a-howto-for-counting-instructions.patch of Package erlang
From 271598649d108957682e61de61d0c91c2392c6a3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 1 Mar 2019 14:04:18 +0100
Subject: [PATCH] Add a howto for counting instructions
---
erts/emulator/internal_doc/CountingInstructions.md | 53 ++++++++++++++++++++++
1 file changed, 53 insertions(+)
create mode 100644 erts/emulator/internal_doc/CountingInstructions.md
diff --git a/erts/emulator/internal_doc/CountingInstructions.md b/erts/emulator/internal_doc/CountingInstructions.md
new file mode 100644
index 0000000000..d4b1213d00
--- /dev/null
+++ b/erts/emulator/internal_doc/CountingInstructions.md
@@ -0,0 +1,53 @@
+Counting Instructions
+=====================
+
+Here is an example that shows how to count how many times each
+instruction is executed:
+
+ $ (cd erts/emulator && make icount)
+ MAKE icount
+ make[1]: Entering directory `/home/uabbgus/otp/erts/emulator'
+ .
+ .
+ .
+ make[1]: Leaving directory `/home/uabbgus/otp/erts/emulator'
+ $ cat t.erl
+ -module(t).
+ -compile([export_all,nowarn_export_all]).
+
+ count() ->
+ erts_debug:ic(fun benchmark/0).
+
+ benchmark() ->
+ %% Run dialyzer.
+ Root = code:root_dir(),
+ Wc1 = filename:join(Root, "lib/{kernel,stdlib}/ebin/*.beam"),
+ Wc2 = filename:join(Root, "erts/preloaded/ebin/*.beam"),
+ Files = filelib:wildcard(Wc1) ++ filelib:wildcard(Wc2),
+ Opts = [{analysis_type,plt_build},{files,Files},{get_warnings,true}],
+ dialyzer:run(Opts).
+ $ $ERL_TOP/bin/cerl -icount
+ Erlang/OTP 22 [RELEASE CANDIDATE 1] [erts-10.2.4] [source-ac0d451] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe] [instruction-counting]
+
+ Eshell V10.2.4 (abort with ^G)
+ 1> c(t).
+ {ok,t}
+ 2> t:count().
+ 0 badarg_j
+ 0 badmatch_x
+ 0 bs_add_jsstx
+ 0 bs_context_to_binary_x
+ .
+ .
+ .
+ 536461394 move_call_last_yfQ
+ 552405176 allocate_tt
+ 619920327 i_is_eq_exact_immed_frc
+ 636419163 is_nonempty_list_allocate_frtt
+ 641859278 i_get_tuple_element_xPx
+ 678196718 move_return_c
+ 786289914 is_tagged_tuple_frAa
+ 865826424 i_call_f
+ Total: 20728870321
+ []
+ 3>
--
2.16.4
