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authorBjörn Gustavsson <[email protected]>2016-05-31 22:49:42 +0200
committerBjörn Gustavsson <[email protected]>2016-06-01 10:09:20 +0200
commitaab1db16d0a732823fa9e2964c6a52b109c61742 (patch)
tree3ba6111af79e023fc1476dc815a14f9f95faa69a /lib/compiler/test
parentac927e00f82b3df962abe082393f45197de49156 (diff)
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beam_block: Eliminate crash in beam_utils
Somewhat simplified, beam_block would rewrite the target for the first instruction in this code sequence: move x(0) => y(1) gc_bif '+' 1 x(0) => y(0) move y(1) => x(1) move nil => x(0) call 2 local_function/2 The resulting code would be: move x(0) => x(1) %% Changed target. gc_bif '+' 1 x(0) => y(0) move x(1) => y(1) %% Operands swapped (see 02d6135813). move nil => x(0) call 2 local_function/2 The resulting code is not safe because the x(1) will be killed by the gc_bif instruction. 7a47b20c3a cleaned up move optimizations and would reject the optimization if the target was an X register and an allocating instruction was found. To avoid this bug, the optimization must be rejected even if the target is a Y register.
Diffstat (limited to 'lib/compiler/test')
-rw-r--r--lib/compiler/test/beam_block_SUITE.erl21
1 files changed, 19 insertions, 2 deletions
diff --git a/lib/compiler/test/beam_block_SUITE.erl b/lib/compiler/test/beam_block_SUITE.erl
index d343e26737..4bcb252833 100644
--- a/lib/compiler/test/beam_block_SUITE.erl
+++ b/lib/compiler/test/beam_block_SUITE.erl
@@ -21,7 +21,7 @@
-export([all/0,suite/0,groups/0,init_per_suite/1,end_per_suite/1,
init_per_group/2,end_per_group/2,
- get_map_elements/1,otp_7345/1]).
+ get_map_elements/1,otp_7345/1,move_opt_across_gc_bif/1]).
%% The only test for the following functions is that
%% the code compiles and is accepted by beam_validator.
@@ -36,7 +36,8 @@ all() ->
groups() ->
[{p,[parallel],
[get_map_elements,
- otp_7345
+ otp_7345,
+ move_opt_across_gc_bif
]}].
init_per_suite(Config) ->
@@ -118,6 +119,22 @@ otp_7345(ObjRef, _RdEnv, Args) ->
10},
id(LlUnitdataReq).
+
+%% Doing move optimizations across GC bifs are in general not safe.
+move_opt_across_gc_bif(_Config) ->
+ [0,true,1] = positive(speaking),
+ ok.
+
+positive(speaking) ->
+ try
+ Positive = 0,
+ [+Positive, case Positive of _ -> true end, paris([], Positive)]
+ after
+ mailing
+ end.
+
+paris([], P) -> P + 1.
+
%%%
%%% The only test of the following code is that it compiles.
%%%