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authorBjörn Gustavsson <[email protected]>2017-08-10 11:46:48 +0200
committerBjörn Gustavsson <[email protected]>2017-08-11 13:44:47 +0200
commit8c0569d2b5c26545cb7abd9063a1abda7ebd13e9 (patch)
treef642c3dbed4f45c217d7312888cfba08b4fd254e /erts/emulator
parent81a6adab693a75f89bc87911ac23a21308673d2d (diff)
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Make '0 bsl BigNumber' consistently succeed
'0 bsl 134217728' would fail with a system limit exception on a 32-bit BEAM machine, but not on a 64-bit BEAM machine. Smaller values on the right would always work. Make erlang:bsl(0, BigNumber) always return 0 to make for consistency. (The previous commit accidentally did that change for '0 bsl BigNumber'.)
Diffstat (limited to 'erts/emulator')
-rw-r--r--erts/emulator/beam/erl_arith.c6
-rw-r--r--erts/emulator/test/big_SUITE.erl7
2 files changed, 12 insertions, 1 deletions
diff --git a/erts/emulator/beam/erl_arith.c b/erts/emulator/beam/erl_arith.c
index 861532f241..f2a3e411ec 100644
--- a/erts/emulator/beam/erl_arith.c
+++ b/erts/emulator/beam/erl_arith.c
@@ -276,8 +276,12 @@ shift(Process* p, Eterm arg1, Eterm arg2, int right)
goto do_bsl;
} else if (is_small(arg1) || is_big(arg1)) {
/*
- * N bsl PositiveBigNum is too large to represent.
+ * N bsl PositiveBigNum is too large to represent,
+ * unless N is 0.
*/
+ if (arg1 == make_small(0)) {
+ BIF_RET(arg1);
+ }
BIF_ERROR(p, SYSTEM_LIMIT);
}
/* Fall through if the left argument is not an integer. */
diff --git a/erts/emulator/test/big_SUITE.erl b/erts/emulator/test/big_SUITE.erl
index c308760211..5939d024ae 100644
--- a/erts/emulator/test/big_SUITE.erl
+++ b/erts/emulator/test/big_SUITE.erl
@@ -339,6 +339,13 @@ system_limit(Config) when is_list(Config) ->
{'EXIT',{system_limit,_}} = (catch apply(erlang, id('bsl'), [Maxbig,2])),
{'EXIT',{system_limit,_}} = (catch id(1) bsl (1 bsl 45)),
{'EXIT',{system_limit,_}} = (catch id(1) bsl (1 bsl 69)),
+
+ %% There should be no system_limit exception when shifting a zero.
+ 0 = id(0) bsl (1 bsl 128),
+ 0 = id(0) bsr -(1 bsl 128),
+ Erlang = id(erlang),
+ 0 = Erlang:'bsl'(id(0), 1 bsl 128),
+ 0 = Erlang:'bsr'(id(0), -(1 bsl 128)),
ok.
maxbig() ->