diff options
| -rw-r--r-- | lib/compiler/src/beam_block.erl | 17 | ||||
| -rw-r--r-- | lib/compiler/test/beam_block_SUITE.erl | 21 |
2 files changed, 30 insertions, 8 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl index a8cfdffdf3..85d332c56e 100644 --- a/lib/compiler/src/beam_block.erl +++ b/lib/compiler/src/beam_block.erl @@ -262,12 +262,17 @@ opt_move_1(R, [{set,[D],[R],move}|Is0], Acc) -> {yes,Is} -> opt_move_rev(D, Acc, Is); no -> not_possible end; -opt_move_1({x,_}, [{set,_,_,{alloc,_,_}}|_], _) -> - %% The optimization is not possible. If the X register is not - %% killed by allocation, the optimization would not be safe. - %% If the X register is killed, it means that there cannot - %% follow a 'move' instruction with this X register as the - %% source. +opt_move_1(_R, [{set,_,_,{alloc,_,_}}|_], _) -> + %% The optimization is either not possible or not safe. + %% + %% If R is an X register killed by allocation, the optimization is + %% not safe. On the other hand, if the X register is killed, there + %% will not follow a 'move' instruction with this X register as + %% the source. + %% + %% If R is a Y register, the optimization is still not safe + %% because the new target register is an X register that cannot + %% safely pass the alloc instruction. not_possible; opt_move_1(R, [{set,_,_,_}=I|Is], Acc) -> %% If the source register is either killed or used by this 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. %%% |