aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--lib/compiler/src/beam_jump.erl58
1 files changed, 28 insertions, 30 deletions
diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl
index db67d24514..79cdc8e179 100644
--- a/lib/compiler/src/beam_jump.erl
+++ b/lib/compiler/src/beam_jump.erl
@@ -260,38 +260,36 @@ find_fixpoint(OptFun, Is0) ->
Is -> find_fixpoint(OptFun, Is)
end.
-opt([{test,Test0,{f,Lnum}=Lbl,Ops}=I|Is0], Acc, St) ->
- case Is0 of
- [{jump,{f,Lnum}}|Is] ->
- %% We have
- %% Test Label Ops
- %% jump Label
- %% The test instruction is definitely not needed.
- %% The jump instruction is not needed if there is
- %% a definition of Label following the jump instruction.
- case is_label_defined(Is, Lnum) of
- false ->
- %% The jump instruction is still needed.
- opt(Is0, [I|Acc], label_used(Lbl, St));
- true ->
- %% Neither the test nor the jump are needed.
- opt(Is, Acc, St)
- end;
- [{jump,To}|Is] ->
- case is_label_defined(Is, Lnum) of
- false ->
+opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc, St) ->
+ %% We have
+ %% Test Label Ops
+ %% jump Label
+ %% The test instruction is not needed if the test is pure
+ %% (it modifies neither registers nor bit syntax state).
+ case beam_utils:is_pure_test(I) of
+ false ->
+ %% Test is not pure; we must keep it.
+ opt(Is, [I|Acc], label_used(Lbl, St));
+ true ->
+ %% The test is pure and its failure label is the same
+ %% as in the jump that follows -- thus it is not needed.
+ opt(Is, Acc, St)
+ end;
+opt([{test,Test0,{f,L}=Lbl,Ops}=I|[{jump,To}|Is]=Is0], Acc, St) ->
+ case is_label_defined(Is, L) of
+ false ->
+ opt(Is0, [I|Acc], label_used(Lbl, St));
+ true ->
+ case invert_test(Test0) of
+ not_possible ->
opt(Is0, [I|Acc], label_used(Lbl, St));
- true ->
- case invert_test(Test0) of
- not_possible ->
- opt(Is0, [I|Acc], label_used(Lbl, St));
- Test ->
- opt([{test,Test,To,Ops}|Is], Acc, St)
- end
- end;
- _Other ->
- opt(Is0, [I|Acc], label_used(Lbl, St))
+ Test ->
+ %% Invert the test and remove the jump.
+ opt([{test,Test,To,Ops}|Is], Acc, St)
+ end
end;
+opt([{test,_,{f,_}=Lbl,_}=I|Is], Acc, St) ->
+ opt(Is, [I|Acc], label_used(Lbl, St));
opt([{test,_,{f,_}=Lbl,_,_,_}=I|Is], Acc, St) ->
opt(Is, [I|Acc], label_used(Lbl, St));
opt([{select_val,_R,Fail,{list,Vls}}=I|Is], Acc, St) ->