From 73cc0c766d0205bec3220ccc1cbe68d35c5759a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn-Egil=20Dahlberg?= <egil@erlang.org>
Date: Wed, 20 May 2015 21:18:44 +0200
Subject: compiler: Teach beam_bsm get_map_elements instruction
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Allows for 'creation of sub binary delayed' optimization if
map instructions are in a clause.

Reported-by: José Valim
---
 lib/compiler/src/beam_bsm.erl | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/compiler/src/beam_bsm.erl b/lib/compiler/src/beam_bsm.erl
index 2a15c1ddf3..ee3e88959d 100644
--- a/lib/compiler/src/beam_bsm.erl
+++ b/lib/compiler/src/beam_bsm.erl
@@ -242,6 +242,12 @@ btb_reaches_match_2([{bif,_,{f,F},Ss,Dst}=I|Is], Regs0, D0) ->
     Regs = btb_kill([Dst], Regs0),
     D = btb_follow_branch(F, Regs, D0),
     btb_reaches_match_1(Is, Regs, D);
+btb_reaches_match_2([{get_map_elements,{f,F},Src,{list,Ls}}=I|Is], Regs0, D0) ->
+    {Ss,Ds} = beam_utils:split_even(Ls),
+    btb_ensure_not_used([Src|Ss], I, Regs0),
+    Regs = btb_kill(Ds, Regs0),
+    D = btb_follow_branch(F, Regs, D0),
+    btb_reaches_match_1(Is, Regs, D);
 btb_reaches_match_2([{test,bs_start_match2,{f,F},Live,[Ctx,_],Ctx}=I|Is],
 		    Regs0, D0) ->
     CtxRegs = btb_context_regs(Regs0),
-- 
cgit v1.2.3


From aec9df2cde184950340888826d84663aec72b5c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn-Egil=20Dahlberg?= <egil@erlang.org>
Date: Wed, 20 May 2015 21:52:34 +0200
Subject: compiler: Add tests for beam_bsm get_map_elements

---
 lib/compiler/test/warnings_SUITE.erl | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/compiler/test/warnings_SUITE.erl b/lib/compiler/test/warnings_SUITE.erl
index f6ba75577d..5742b7e6cf 100644
--- a/lib/compiler/test/warnings_SUITE.erl
+++ b/lib/compiler/test/warnings_SUITE.erl
@@ -38,7 +38,8 @@
 -export([pattern/1,pattern2/1,pattern3/1,pattern4/1,
 	 guard/1,bad_arith/1,bool_cases/1,bad_apply/1,
          files/1,effect/1,bin_opt_info/1,bin_construction/1,
-	 comprehensions/1,maps/1,redundant_boolean_clauses/1,
+	 comprehensions/1,maps/1,maps_bin_opt_info/1,
+         redundant_boolean_clauses/1,
 	 latin1_fallback/1,underscore/1,no_warnings/1]).
 
 % Default timetrap timeout (set in init_per_testcase).
@@ -64,6 +65,7 @@ groups() ->
       [pattern,pattern2,pattern3,pattern4,guard,
        bad_arith,bool_cases,bad_apply,files,effect,
        bin_opt_info,bin_construction,comprehensions,maps,
+       maps_bin_opt_info,
        redundant_boolean_clauses,latin1_fallback,
        underscore,no_warnings]}].
 
@@ -619,6 +621,19 @@ maps(Config) when is_list(Config) ->
     run(Config, Ts),
     ok.
 
+maps_bin_opt_info(Config) when is_list(Config) ->
+    Ts = [{map_bsm,
+           <<"
+             t1(<<0:8,7:8,T/binary>>,#{val := I}=M) ->
+                 t1(T, M#{val := I+1});
+             t1(<<_:8>>,M) ->
+                 M.
+           ">>,
+           [bin_opt_info],
+           {warnings,[{2,beam_bsm,bin_opt}]}}],
+    [] = run(Config, Ts),
+    ok.
+
 redundant_boolean_clauses(Config) when is_list(Config) ->
     Ts = [{redundant_boolean_clauses,
            <<"
-- 
cgit v1.2.3