From 4ad250c85a1abb80b6e0a30855c8982d174b369c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 19 Jan 2018 12:37:49 +0100
Subject: Optimize matching of empty binaries

Extend an existing optimization in beam_dead to avoid
creating a match context when matching an empty binary.
---
 lib/compiler/test/bs_match_SUITE.erl | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'lib/compiler/test')

diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index 4bd5e8e2e1..235956a714 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -678,6 +678,10 @@ coverage(Config) when is_list(Config) ->
     <<>> = coverage_per_key(<<4:32>>),
     <<$a,$b,$c>> = coverage_per_key(<<7:32,"abc">>),
 
+    binary = coverage_bitstring(<<>>),
+    binary = coverage_bitstring(<<7>>),
+    bitstring = coverage_bitstring(<<7:4>>),
+    other = coverage_bitstring([a]),
     ok.
 
 coverage_fold(Fun, Acc, <<H,T/binary>>) ->
@@ -768,6 +772,10 @@ coverage_per_key(<<BinSize:32,Bin/binary>> = B) ->
     true = (byte_size(B) =:= BinSize),
     Bin.
 
+coverage_bitstring(Bin) when is_binary(Bin) -> binary;
+coverage_bitstring(<<_/bitstring>>) -> bitstring;
+coverage_bitstring(_) -> other.
+
 multiple_uses(Config) when is_list(Config) ->
     {344,62879,345,<<245,159,1,89>>} = multiple_uses_1(<<1,88,245,159,1,89>>),
     true = multiple_uses_2(<<0,0,197,18>>),
-- 
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