Merge pull request #159 from aeternity/more-compiler-fixes

Fix issues with liveness analysis
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Ulf Norell 2019-09-27 08:45:37 +02:00 committed by GitHub
commit 9234690d31
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@ -741,18 +741,20 @@ ann_reads([{switch, Arg, Type, Alts, Def} | Code], Reads, Acc) ->
ann_reads([{i, Ann, I} | Code], Reads, Acc) ->
#{ writes_in := WritesIn, writes_out := WritesOut } = Ann,
#{ read := Rs, write := W, pure := Pure } = attributes(I),
Reads1 =
%% If we write it here it's not live in (unless we also read it)
Reads1 = Reads -- [W],
Reads2 =
case {W, Pure andalso not ordsets:is_element(W, Reads)} of
%% This is a little bit dangerous: if writing to a dead variable, we ignore
%% the reads. Relies on dead writes to be removed by the
%% optimisations below (r_write_to_dead_var).
{{var, _}, true} -> Reads;
_ -> ordsets:union(Reads, Rs)
{{var, _}, true} -> Reads1;
_ -> ordsets:union(Reads1, Rs)
end,
LiveIn = ordsets:intersection(Reads1, WritesIn),
LiveIn = ordsets:intersection(Reads2, WritesIn),
LiveOut = ordsets:intersection(Reads, WritesOut),
Ann1 = #{ live_in => LiveIn, live_out => LiveOut },
ann_reads(Code, Reads1, [{i, Ann1, I} | Acc]);
ann_reads(Code, Reads2, [{i, Ann1, I} | Acc]);
ann_reads([], Reads, Acc) -> {Acc, Reads}.
%% Instruction attributes: reads, writes and purity (pure means no side-effects
@ -922,6 +924,7 @@ independent({i, _, I}, {i, _, J}) ->
if WI == pc; WJ == pc -> false; %% no jumps
not (PureI or PureJ) -> false; %% at least one is pure
StackI and StackJ -> false; %% cannot both use the stack
WI == WJ -> false; %% cannot write to the same register
true ->
%% and cannot write to each other's inputs
not lists:member(WI, RJ) andalso