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authorBjörn Gustavsson <[email protected]>2016-08-19 14:07:38 +0200
committerBjörn Gustavsson <[email protected]>2016-08-19 15:04:33 +0200
commita66a2e84ec4c6fb7c19affe43134570caabe8569 (patch)
treea10bf3e5fbfc7acaedb8006ba39ed400cc790486
parent3060758b3c88994eee5a4be8d3f29eded81eb201 (diff)
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Reinstate optimization of binary literal matching
105c5b0071 was reverted in dd1162846e because clauses that were supposed to match would not match. (See 8b83bc0b.) Reintroduce the optimization, but make sure that we only shortcut bs_context_to_binary instructions and not bs_start_match2 instructions.
-rw-r--r--lib/compiler/src/beam_dead.erl23
1 files changed, 21 insertions, 2 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl
index 6f6d742293..3606af9d75 100644
--- a/lib/compiler/src/beam_dead.erl
+++ b/lib/compiler/src/beam_dead.erl
@@ -272,14 +272,18 @@ backward([{jump,{f,To}}=J|[{bif,Op,_,Ops,Reg}|Is]=Is0], D, Acc) ->
catch
throw:not_possible -> backward(Is0, D, [J|Acc])
end;
-backward([{test,bs_start_match2,F,_,[R,_],Ctxt}=I|Is], D,
+backward([{test,bs_start_match2,F,Live,[R,_]=Args,Ctxt}|Is], D,
[{test,bs_match_string,F,[Ctxt,Bs]},
{test,bs_test_tail2,F,[Ctxt,0]}|Acc0]=Acc) ->
+ {f,To0} = F,
case beam_utils:is_killed(Ctxt, Acc0, D) of
true ->
- Eq = {test,is_eq_exact,F,[R,{literal,Bs}]},
+ To = shortcut_bs_context_to_binary(To0, R, D),
+ Eq = {test,is_eq_exact,{f,To},[R,{literal,Bs}]},
backward(Is, D, [Eq|Acc0]);
false ->
+ To = shortcut_bs_start_match(To0, R, D),
+ I = {test,bs_start_match2,{f,To},Live,Args,Ctxt},
backward(Is, D, [I|Acc])
end;
backward([{test,bs_start_match2,{f,To0},Live,[Src|_]=Info,Dst}|Is], D, Acc) ->
@@ -551,6 +555,21 @@ shortcut_bs_start_match_1([{test,bs_start_match2,{f,To},_,[Reg|_],_}|_],
shortcut_bs_start_match_1(_, _, To, _) ->
To.
+%% shortcut_bs_context_to_binary(TargetLabel, Reg) -> TargetLabel
+%% If a bs_start_match2 instruction has been eliminated, the
+%% bs_context_to_binary instruction can be eliminated too.
+
+shortcut_bs_context_to_binary(To, Reg, D) ->
+ shortcut_bs_ctb_1(beam_utils:code_at(To, D), Reg, To, D).
+
+shortcut_bs_ctb_1([{bs_context_to_binary,Reg}|Is], Reg, To, D) ->
+ shortcut_bs_ctb_1(Is, Reg, To, D);
+shortcut_bs_ctb_1([{jump,{f,To}}|_], Reg, _, D) ->
+ Code = beam_utils:code_at(To, D),
+ shortcut_bs_ctb_1(Code, Reg, To, D);
+shortcut_bs_ctb_1(_, _, To, _) ->
+ To.
+
%% shortcut_rel_op(FailLabel, Operator, [Operand], D) -> FailLabel'
%% Try to shortcut the given test instruction. Example:
%%