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-rw-r--r--lib/compiler/src/beam_ssa_pre_codegen.erl62
-rw-r--r--lib/compiler/test/beam_ssa_SUITE.erl26
2 files changed, 84 insertions, 4 deletions
diff --git a/lib/compiler/src/beam_ssa_pre_codegen.erl b/lib/compiler/src/beam_ssa_pre_codegen.erl
index 7022b1d316..28b2e55c43 100644
--- a/lib/compiler/src/beam_ssa_pre_codegen.erl
+++ b/lib/compiler/src/beam_ssa_pre_codegen.erl
@@ -159,7 +159,9 @@ passes(Opts) ->
%% Allocate registers.
?PASS(linear_scan),
?PASS(frame_size),
- ?PASS(turn_yregs)],
+ ?PASS(turn_yregs),
+
+ ?PASS(assert_no_critical_edges)],
[P || P <- Ps, P =/= ignore].
function(#b_function{anno=Anno,args=Args,bs=Blocks0,cnt=Count0}=F0,
@@ -1472,10 +1474,11 @@ fix_receives_1([{L,Blk}|Ls], Blocks0, Count0) ->
LoopExit = find_loop_exit(Rm, Blocks0),
Defs0 = beam_ssa:def([L], Blocks0),
CommonUsed = recv_common(Defs0, LoopExit, Blocks0),
- {Blocks1,Count1} = recv_fix_common(CommonUsed, LoopExit, Rm,
- Blocks0, Count0),
+ {Blocks1,Count1} = recv_crit_edges(Rm, LoopExit, Blocks0, Count0),
+ {Blocks2,Count2} = recv_fix_common(CommonUsed, LoopExit, Rm,
+ Blocks1, Count1),
Defs = ordsets:subtract(Defs0, CommonUsed),
- {Blocks,Count} = fix_receive(Rm, Defs, Blocks1, Count1),
+ {Blocks,Count} = fix_receive(Rm, Defs, Blocks2, Count2),
fix_receives_1(Ls, Blocks, Count);
#b_blk{} ->
fix_receives_1(Ls, Blocks0, Count0)
@@ -1492,6 +1495,57 @@ recv_common(Defs, Exit, Blocks) ->
Def = ordsets:subtract(Defs, ExitDefs),
ordsets:subtract(Def, ExitUnused).
+%% recv_crit_edges([RemoveMessageLabel], LoopExit,
+%% Blocks0, Count0) -> {Blocks,Count}.
+%%
+%% Adds dummy blocks on all conditional jumps to the exit block so that
+%% recv_fix_common/5 can insert phi nodes without having to worry about
+%% critical edges.
+
+recv_crit_edges(_Rms, none, Blocks0, Count0) ->
+ {Blocks0, Count0};
+recv_crit_edges(Rms, Exit, Blocks0, Count0) ->
+ Ls = beam_ssa:rpo(Rms, Blocks0),
+ rce_insert_edges(Ls, Exit, Count0, Blocks0).
+
+rce_insert_edges([L | Ls], Exit, Count0, Blocks0) ->
+ Successors = beam_ssa:successors(map_get(L, Blocks0)),
+ case member(Exit, Successors) of
+ true when Successors =/= [Exit] ->
+ {Blocks, Count} = rce_insert_edge(L, Exit, Count0, Blocks0),
+ rce_insert_edges(Ls, Exit, Count, Blocks);
+ _ ->
+ rce_insert_edges(Ls, Exit, Count0, Blocks0)
+ end;
+rce_insert_edges([], _Exit, Count, Blocks) ->
+ {Blocks, Count}.
+
+rce_insert_edge(L, Exit, Count, Blocks0) ->
+ #b_blk{last=Last0} = FromBlk0 = map_get(L, Blocks0),
+
+ ToExit = #b_br{bool=#b_literal{val=true},succ=Exit,fail=Exit},
+
+ FromBlk = FromBlk0#b_blk{last=rce_reroute_terminator(Last0, Exit, Count)},
+ EdgeBlk = #b_blk{anno=#{},is=[],last=ToExit},
+
+ Blocks = Blocks0#{ Count => EdgeBlk, L => FromBlk },
+ {Blocks, Count + 1}.
+
+rce_reroute_terminator(#b_br{succ=Exit}=Last, Exit, New) ->
+ rce_reroute_terminator(Last#b_br{succ=New}, Exit, New);
+rce_reroute_terminator(#b_br{fail=Exit}=Last, Exit, New) ->
+ rce_reroute_terminator(Last#b_br{fail=New}, Exit, New);
+rce_reroute_terminator(#b_br{}=Last, _Exit, _New) ->
+ Last;
+rce_reroute_terminator(#b_switch{fail=Exit}=Last, Exit, New) ->
+ rce_reroute_terminator(Last#b_switch{fail=New}, Exit, New);
+rce_reroute_terminator(#b_switch{list=List0}=Last, Exit, New) ->
+ List = [if
+ Lbl =:= Exit -> {Arg, New};
+ Lbl =/= Exit -> {Arg, Lbl}
+ end || {Arg, Lbl} <- List0],
+ Last#b_switch{list=List}.
+
%% recv_fix_common([CommonVar], LoopExit, [RemoveMessageLabel],
%% Blocks0, Count0) -> {Blocks,Count}.
%% Handle variables alwys defined in a receive and used
diff --git a/lib/compiler/test/beam_ssa_SUITE.erl b/lib/compiler/test/beam_ssa_SUITE.erl
index 96cc846799..11bd5cf07d 100644
--- a/lib/compiler/test/beam_ssa_SUITE.erl
+++ b/lib/compiler/test/beam_ssa_SUITE.erl
@@ -190,6 +190,12 @@ recv(_Config) ->
self() ! {[self(),r1],{2,99,<<"data">>}},
{Parent,r1,<<1:32,2:8,99:8,"data">>} = tricky_recv_4(),
+ %% Test tricky_recv_5/0.
+ self() ! 1,
+ a = tricky_recv_5(),
+ self() ! 2,
+ b = tricky_recv_5(),
+
ok.
sync_wait_mon({Pid, Ref}, Timeout) ->
@@ -295,6 +301,26 @@ tricky_recv_4() ->
end,
id({Pid,R,Request}).
+%% beam_ssa_pre_codegen would accidentally create phi nodes on critical edges
+%% when fixing up receives; the call to id/2 can either succeed or land in the
+%% catch block, and we added a phi node to its immediate successor.
+tricky_recv_5() ->
+ try
+ receive
+ X=1 ->
+ id(42),
+ a;
+ X=2 ->
+ b
+ end,
+ case X of
+ 1 -> a;
+ 2 -> b
+ end
+ catch
+ _:_ -> c
+ end.
+
maps(_Config) ->
{'EXIT',{{badmatch,#{}},_}} = (catch maps_1(any)),
ok.