diff options
| -rw-r--r-- | lib/compiler/src/beam_bsm.erl | 31 | ||||
| -rw-r--r-- | lib/compiler/test/bs_match_SUITE.erl | 23 |
2 files changed, 44 insertions, 10 deletions
diff --git a/lib/compiler/src/beam_bsm.erl b/lib/compiler/src/beam_bsm.erl index 286307a4be..ae1b34ba49 100644 --- a/lib/compiler/src/beam_bsm.erl +++ b/lib/compiler/src/beam_bsm.erl @@ -205,8 +205,15 @@ btb_reaches_match_1(Is, Regs, D) -> btb_reaches_match_2([{block,Bl}|Is], Regs0, D) -> Regs = btb_reaches_match_block(Bl, Regs0), btb_reaches_match_1(Is, Regs, D); -btb_reaches_match_2([{call,Arity,{f,Lbl}}|Is], Regs, D) -> - btb_call(Arity, Lbl, Regs, Is, D); +btb_reaches_match_2([{call,Arity,{f,Lbl}}|Is], Regs0, D) -> + case is_tail_call(Is) of + true -> + Regs1 = btb_kill_not_live(Arity, Regs0), + Regs = btb_kill_yregs(Regs1), + btb_tail_call(Lbl, Regs, D); + false -> + btb_call(Arity, Lbl, Regs0, Is, D) + end; btb_reaches_match_2([{apply,Arity}|Is], Regs, D) -> btb_call(Arity+2, apply, Regs, Is, D); btb_reaches_match_2([{call_fun,Live}=I|Is], Regs, D) -> @@ -360,6 +367,10 @@ btb_reaches_match_2([{line,_}|Is], Regs, D) -> btb_reaches_match_2([I|_], Regs, _) -> btb_error({btb_context_regs(Regs),I,not_handled}). +is_tail_call([{deallocate,_}|_]) -> true; +is_tail_call([return|_]) -> true; +is_tail_call(_) -> false. + btb_call(Arity, Lbl, Regs0, Is, D0) -> Regs = btb_kill_not_live(Arity, Regs0), case btb_are_x_registers_empty(Regs) of @@ -369,15 +380,15 @@ btb_call(Arity, Lbl, Regs0, Is, D0) -> D = btb_tail_call(Lbl, Regs, D0), %% No problem so far (the called function can handle a - %% match context). Now we must make sure that the rest - %% of this function following the call does not attempt - %% to use the match context in case there is a copy - %% tucked away in a y register. + %% match context). Now we must make sure that we don't + %% have any copies of the match context tucked away in an + %% y register. RegList = btb_context_regs(Regs), - YRegs = [R || {y,_}=R <- RegList], - case btb_are_all_unused(YRegs, Is, D) of - true -> D; - false -> btb_error({multiple_uses,RegList}) + case [R || {y,_}=R <- RegList] of + [] -> + D; + [_|_] -> + btb_error({multiple_uses,RegList}) end; true -> %% No match context in any x register. It could have been diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl index f8af070c44..6742571b86 100644 --- a/lib/compiler/test/bs_match_SUITE.erl +++ b/lib/compiler/test/bs_match_SUITE.erl @@ -769,6 +769,11 @@ 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>>), <<42,43>> = multiple_uses_3(<<0,0,42,43>>, fun id/1), + + ok = first_after(<<>>, 42), + <<1>> = first_after(<<1,2,3>>, 0), + <<2>> = first_after(<<1,2,3>>, 1), + ok. multiple_uses_1(<<X:16,Tail/binary>>) -> @@ -790,6 +795,24 @@ multiple_uses_match(<<Y:16,Z:16>>) -> multiple_uses_cmp(<<Y:16>>, <<Y:16>>) -> true; multiple_uses_cmp(<<_:16>>, <<_:16>>) -> false. +first_after(Data, Offset) -> + case byte_size(Data) > Offset of + false -> + {First, Rest} = {ok, ok}, + ok; + true -> + <<_:Offset/binary, Rest/binary>> = Data, + %% 'Rest' saved in y(0) before the call. + {First, _} = match_first(Data, Rest), + %% When beam_bsm sees the code, the following line + %% which uses y(0) has been optimized away. + {First, Rest} = {First, Rest}, + First + end. + +match_first(_, <<First:1/binary, Rest/binary>>) -> + {First, Rest}. + zero_label(Config) when is_list(Config) -> <<"nosemouth">> = read_pols(<<"FACE","nose","mouth">>), <<"CE">> = read_pols(<<"noFACE">>), |