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-rw-r--r--lib/compiler/src/beam_bsm.erl68
-rw-r--r--lib/compiler/src/beam_jump.erl2
-rw-r--r--lib/compiler/src/beam_utils.erl18
-rw-r--r--lib/compiler/test/bs_match_SUITE.erl30
4 files changed, 81 insertions, 37 deletions
diff --git a/lib/compiler/src/beam_bsm.erl b/lib/compiler/src/beam_bsm.erl
index 37053e1cc4..02794a8e18 100644
--- a/lib/compiler/src/beam_bsm.erl
+++ b/lib/compiler/src/beam_bsm.erl
@@ -241,21 +241,45 @@ btb_reaches_match_2([{bif,_,{f,F},Ss,Dst}=I|Is], Regs0, D0) ->
Regs = btb_kill([Dst], Regs0),
D = btb_follow_branch(F, Regs, D0),
btb_reaches_match_1(Is, Regs, D);
-btb_reaches_match_2([{test,bs_start_match2,_,_,[Ctx,_],Ctx}|Is], Regs, D) ->
- case btb_context_regs(Regs) of
- [Ctx] ->
- D;
- CtxRegs ->
- case member(Ctx, CtxRegs) of
- false -> btb_reaches_match_2(Is, Regs, D);
- true -> btb_error(unsuitable_bs_start_match)
+btb_reaches_match_2([{test,bs_start_match2,{f,F},Live,[Ctx,_],Ctx}=I|Is],
+ Regs0, D0) ->
+ CtxRegs = btb_context_regs(Regs0),
+ case member(Ctx, CtxRegs) of
+ false ->
+ %% This bs_start_match2 instruction does not use "our"
+ %% match state. Therefore we can continue the search
+ %% for another bs_start_match2 instruction.
+ D = btb_follow_branch(F, Regs0, D0),
+ Regs = btb_kill_not_live(Live, Regs0),
+ btb_reaches_match_2(Is, Regs, D);
+ true ->
+ %% OK. This instruction will use "our" match state,
+ %% but we must make sure that all other copies of the
+ %% match state are killed in the code that follows
+ %% the instruction. (We know that the fail branch cannot
+ %% be taken in this case.)
+ OtherCtxRegs = CtxRegs -- [Ctx],
+ case btb_are_all_unused(OtherCtxRegs, Is, D0) of
+ false -> btb_error({OtherCtxRegs,not_all_unused_after,I});
+ true -> D0
end
end;
-btb_reaches_match_2([{test,bs_start_match2,_,_,[Bin,_],Ctx}|Is], Regs, D) ->
- CtxRegs = btb_context_regs(Regs),
+btb_reaches_match_2([{test,bs_start_match2,{f,F},Live,[Bin,_],Ctx}|Is],
+ Regs0, D0) ->
+ CtxRegs = btb_context_regs(Regs0),
case member(Bin, CtxRegs) orelse member(Ctx, CtxRegs) of
- false -> btb_reaches_match_2(Is, Regs, D);
- true -> btb_error(unsuitable_bs_start_match)
+ false ->
+ %% This bs_start_match2 does not reference any copy of the
+ %% match state. Therefore it can safely be passed on the
+ %% way to another (perhaps more suitable) bs_start_match2
+ %% instruction.
+ D = btb_follow_branch(F, Regs0, D0),
+ Regs = btb_kill_not_live(Live, Regs0),
+ btb_reaches_match_2(Is, Regs, D);
+ true ->
+ %% This variant of the bs_start_match2 instruction does
+ %% not accept a match state as source.
+ btb_error(unsuitable_bs_start_match)
end;
btb_reaches_match_2([{test,_,{f,F},Ss}=I|Is], Regs, D0) ->
btb_ensure_not_used(Ss, I, Regs),
@@ -287,11 +311,11 @@ btb_reaches_match_2([{bs_restore2,Src,_}=I|Is], Regs0, D) ->
btb_reaches_match_1(Is, Regs0, D);
true ->
%% Check that all other copies of the context registers
- %% are killed by the following instructions.
+ %% are unused by the following instructions.
Regs = btb_kill([Src], Regs0),
CtxRegs = btb_context_regs(Regs),
- case btb_are_all_killed(CtxRegs, Is, D) of
- false -> btb_error({CtxRegs,not_all_killed_after,I});
+ case btb_are_all_unused(CtxRegs, Is, D) of
+ false -> btb_error({CtxRegs,not_all_unused_after,I});
true -> D#btb{must_not_save=true}
end
end;
@@ -301,11 +325,11 @@ btb_reaches_match_2([{bs_context_to_binary,Src}=I|Is], Regs0, D) ->
btb_reaches_match_1(Is, Regs0, D);
true ->
%% Check that all other copies of the context registers
- %% are killed by the following instructions.
+ %% are unused by the following instructions.
Regs = btb_kill([Src], Regs0),
CtxRegs = btb_context_regs(Regs),
- case btb_are_all_killed(CtxRegs, Is, D) of
- false -> btb_error({CtxRegs,not_all_killed_after,I});
+ case btb_are_all_unused(CtxRegs, Is, D) of
+ false -> btb_error({CtxRegs,not_all_unused_after,I});
true -> D#btb{must_not_save=true}
end
end;
@@ -343,7 +367,7 @@ btb_call(Arity, Lbl, Regs0, Is, D0) ->
%% tucked away in a y register.
RegList = btb_context_regs(Regs),
YRegs = [R || {y,_}=R <- RegList],
- case btb_are_all_killed(YRegs, Is, D) of
+ case btb_are_all_unused(YRegs, Is, D) of
true -> D;
false -> btb_error({multiple_uses,RegList})
end;
@@ -426,11 +450,11 @@ btb_reaches_match_block([], Regs) ->
Regs.
%% btb_are_all_killed([Register], [Instruction], D) -> true|false
-%% Test whether all of the register are killed in the instruction stream.
+%% Test whether all of the register are unused in the instruction stream.
-btb_are_all_killed(RegList, Is, #btb{index=Li}) ->
+btb_are_all_unused(RegList, Is, #btb{index=Li}) ->
all(fun(R) ->
- beam_utils:is_killed(R, Is, Li)
+ beam_utils:is_not_used(R, Is, Li)
end, RegList).
%% btp_regs_from_list([Register]) -> RegisterSet.
diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl
index b05d01b2a1..636c299e47 100644
--- a/lib/compiler/src/beam_jump.erl
+++ b/lib/compiler/src/beam_jump.erl
@@ -220,6 +220,8 @@ extract_seq([{line,_}=Line|Is], Acc) ->
extract_seq(Is, [Line|Acc]);
extract_seq([{block,_}=Bl|Is], Acc) ->
extract_seq_1(Is, [Bl|Acc]);
+extract_seq([{bs_context_to_binary,_}=I|Is], Acc) ->
+ extract_seq_1(Is, [I|Acc]);
extract_seq([{label,_}|_]=Is, Acc) ->
extract_seq_1(Is, Acc);
extract_seq(_, _) -> no.
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 8b661e6901..8af0447f63 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -263,19 +263,11 @@ check_liveness(R, [{test,_,{f,Fail},As}|Is], St0) ->
{_,_}=Other -> Other
end
end;
-check_liveness(R, [{test,_,{f,Fail},Live,Ss,_}|Is], St0) ->
- case R of
- {x,X} ->
- case X < Live orelse member(R, Ss) of
- true -> {used,St0};
- false -> check_liveness_at(R, Fail, St0)
- end;
- {y,_} ->
- case check_liveness_at(R, Fail, St0) of
- {killed,St} -> check_liveness(R, Is, St);
- {_,_}=Other -> Other
- end
- end;
+check_liveness(R, [{test,Op,Fail,Live,Ss,Dst}|Is], St) ->
+ %% Check this instruction as a block to get a less conservative
+ %% result if the caller is is_not_used/3.
+ Block = [{set,[Dst],Ss,{alloc,Live,{bif,Op,Fail}}}],
+ check_liveness(R, [{block,Block}|Is], St);
check_liveness(R, [{select,_,R,_,_}|_], St) ->
{used,St};
check_liveness(R, [{select,_,_,Fail,Branches}|_], St) ->
diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index e8f5c55c1a..d63d2235d7 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -33,7 +33,7 @@
matching_meets_construction/1,simon/1,matching_and_andalso/1,
otp_7188/1,otp_7233/1,otp_7240/1,otp_7498/1,
match_string/1,zero_width/1,bad_size/1,haystack/1,
- cover_beam_bool/1,matched_out_size/1]).
+ cover_beam_bool/1,matched_out_size/1,follow_fail_branch/1]).
-export([coverage_id/1,coverage_external_ignore/2]).
@@ -57,7 +57,7 @@ groups() ->
matching_meets_construction,simon,
matching_and_andalso,otp_7188,otp_7233,otp_7240,
otp_7498,match_string,zero_width,bad_size,haystack,
- cover_beam_bool,matched_out_size]}].
+ cover_beam_bool,matched_out_size,follow_fail_branch]}].
init_per_suite(Config) ->
@@ -1108,6 +1108,32 @@ mos_bin(<<L,Bin:L/binary,"abcdefghij">>) ->
L = byte_size(Bin),
Bin.
+follow_fail_branch(_) ->
+ 42 = ffb_1(<<0,1>>, <<0>>),
+ 8 = ffb_1(<<0,1>>, [a]),
+ 42 = ffb_2(<<0,1>>, <<0>>, 17),
+ 8 = ffb_2(<<0,1>>, [a], 0),
+ ok.
+
+ffb_1(<<_,T/bitstring>>, List) ->
+ case List of
+ <<_>> ->
+ 42;
+ [_|_] ->
+ %% The fail branch of the bs_start_match2 instruction
+ %% pointing to here would be ignored, making the compiler
+ %% incorrectly assume that the delayed sub-binary
+ %% optimization was safe.
+ bit_size(T)
+ end.
+
+ffb_2(<<_,T/bitstring>>, List, A) ->
+ case List of
+ <<_>> when A =:= 17 -> 42;
+ [_|_] -> bit_size(T)
+ end.
+
+
check(F, R) ->
R = F().
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-09 12:13:58 +0000