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authorBjörn Gustavsson <[email protected]>2014-12-28 11:47:26 +0100
committerBjörn Gustavsson <[email protected]>2015-01-09 13:18:45 +0100
commitc01e015797153b56cd6b32cab94b8b6b30975f7e (patch)
tree291749e02250b4e41124bfe04224bf273c856121
parent5e495894c82575e426a3a45b08c24e1538d75129 (diff)
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Improve optimization of bs_start_match2
-rw-r--r--lib/compiler/src/beam_dead.erl30
1 files changed, 16 insertions, 14 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl
index aaad7f4095..7e582a2b43 100644
--- a/lib/compiler/src/beam_dead.erl
+++ b/lib/compiler/src/beam_dead.erl
@@ -516,22 +516,24 @@ shortcut_bs_pos_used_1(Is, Reg, D) ->
not beam_utils:is_killed(Reg, Is, D).
%% shortcut_bs_start_match(TargetLabel, Reg) -> TargetLabel
-%% A failing bs_start_match2 instruction means that the source
-%% cannot be a binary, so there is no need to jump bs_context_to_binary/1
-%% or another bs_start_match2 instruction.
+%% A failing bs_start_match2 instruction means that the source (Reg)
+%% cannot be a binary. That means that it is safe to skip
+%% bs_context_to_binary instructions operating on Reg, and
+%% bs_start_match2 instructions operating on Reg.
shortcut_bs_start_match(To, Reg, D) ->
- shortcut_bs_start_match_1(beam_utils:code_at(To, D), Reg, To).
-
-shortcut_bs_start_match_1([{bs_context_to_binary,Reg}|Is], Reg, To) ->
- shortcut_bs_start_match_2(Is, Reg, To);
-shortcut_bs_start_match_1(_, _, To) -> To.
-
-shortcut_bs_start_match_2([{jump,{f,To}}|_], _, _) ->
- To;
-shortcut_bs_start_match_2([{test,bs_start_match2,{f,To},_,[Reg|_],_}|_], Reg, _) ->
- To;
-shortcut_bs_start_match_2(_Is, _Reg, To) ->
+ shortcut_bs_start_match_1(beam_utils:code_at(To, D), Reg, To, D).
+
+shortcut_bs_start_match_1([{bs_context_to_binary,Reg}|Is], Reg, To, D) ->
+ shortcut_bs_start_match_1(Is, Reg, To, D);
+shortcut_bs_start_match_1([{jump,{f,To}}|_], Reg, _, D) ->
+ Code = beam_utils:code_at(To, D),
+ shortcut_bs_start_match_1(Code, Reg, To, D);
+shortcut_bs_start_match_1([{test,bs_start_match2,{f,To},_,[Reg|_],_}|_],
+ Reg, _, D) ->
+ Code = beam_utils:code_at(To, D),
+ shortcut_bs_start_match_1(Code, Reg, To, D);
+shortcut_bs_start_match_1(_, _, To, _) ->
To.
%% shortcut_rel_op(FailLabel, Operator, [Operand], D) -> FailLabel'