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-rw-r--r--lib/compiler/src/beam_ssa_opt.erl112
1 files changed, 66 insertions, 46 deletions
diff --git a/lib/compiler/src/beam_ssa_opt.erl b/lib/compiler/src/beam_ssa_opt.erl
index 986be14e8a..f77eeecc94 100644
--- a/lib/compiler/src/beam_ssa_opt.erl
+++ b/lib/compiler/src/beam_ssa_opt.erl
@@ -901,6 +901,7 @@ cse_suitable(#b_set{}) -> false.
-record(fs,
{s=undefined :: 'undefined' | 'cleared',
regs=#{} :: #{beam_ssa:b_var():=beam_ssa:b_var()},
+ vars=cerl_sets:new() :: cerl_sets:set(),
fail=none :: 'none' | beam_ssa:label(),
non_guards :: gb_sets:set(beam_ssa:label()),
bs :: beam_ssa:block_map()
@@ -913,22 +914,39 @@ ssa_opt_float({#st{ssa=Linear0,cnt=Count0}=St, FuncDb}) ->
{Linear,Count} = float_opt(Linear0, Count0, Fs),
{St#st{ssa=Linear,cnt=Count}, FuncDb}.
-float_blk_is_in_guard(#b_blk{last=#b_br{fail=F}}, #fs{non_guards=NonGuards}) ->
- not gb_sets:is_member(F, NonGuards);
-float_blk_is_in_guard(#b_blk{}, #fs{}) ->
+%% The fconv instruction doesn't support jumping to a fail label, so we have to
+%% skip this optimization if the fail block is a guard.
+%%
+%% We also skip the optimization in blocks that always fail, as it's both
+%% difficult and pointless to rewrite them to use float ops.
+float_can_optimize_blk(#b_blk{last=#b_br{bool=#b_var{},fail=F}},
+ #fs{non_guards=NonGuards}) ->
+ gb_sets:is_member(F, NonGuards);
+float_can_optimize_blk(#b_blk{}, #fs{}) ->
false.
+float_opt([{L,#b_blk{is=[#b_set{op=exception_trampoline,args=[Var]}]}=Blk0} |
+ Bs0], Count0, Fs) ->
+ %% If we've replaced a BIF with float operations, we'll have a lot of extra
+ %% blocks that jump to the same failure block, which may have a trampoline
+ %% that refers to the original operation.
+ %%
+ %% Since the point of the trampoline is to keep the BIF from being removed
+ %% by liveness optimization, we can discard it as the liveness pass leaves
+ %% floats alone.
+ Blk = case cerl_sets:is_element(Var, Fs#fs.vars) of
+ true -> Blk0#b_blk{is=[]};
+ false -> Blk0
+ end,
+ {Bs, Count} = float_opt(Bs0, Count0, Fs),
+ {[{L,Blk}|Bs],Count};
float_opt([{L,Blk}|Bs0], Count0, Fs) ->
- case float_blk_is_in_guard(Blk, Fs) of
+ case float_can_optimize_blk(Blk, Fs) of
true ->
- %% This block is inside a guard. Don't do
- %% any floating point optimizations.
- {Bs,Count} = float_opt(Bs0, Count0, Fs),
- {[{L,Blk}|Bs],Count};
+ float_opt_1(L, Blk, Bs0, Count0, Fs);
false ->
- %% This block is not inside a guard.
- %% We can do the optimization.
- float_opt_1(L, Blk, Bs0, Count0, Fs)
+ {Bs,Count} = float_opt(Bs0, Count0, Fs),
+ {[{L,Blk}|Bs],Count}
end;
float_opt([], Count, _Fs) ->
{[],Count}.
@@ -1007,12 +1025,12 @@ float_maybe_flush(Blk0, #fs{s=cleared,fail=Fail,bs=Blocks}=Fs0, Count0) ->
#b_blk{last=#b_br{bool=#b_var{},succ=Succ}=Br} = Blk0,
%% If the success block starts with a floating point operation, we can
- %% defer flushing to that block as long as it isn't a guard.
+ %% defer flushing to that block as long as it's suitable for optimization.
#b_blk{is=Is} = SuccBlk = map_get(Succ, Blocks),
- SuccIsGuard = float_blk_is_in_guard(SuccBlk, Fs0),
+ CanOptimizeSucc = float_can_optimize_blk(SuccBlk, Fs0),
case Is of
- [#b_set{anno=#{float_op:=_}}|_] when not SuccIsGuard ->
+ [#b_set{anno=#{float_op:=_}}|_] when CanOptimizeSucc ->
%% No flush needed.
{[],Blk0,Fs0,Count0};
_ ->
@@ -1068,21 +1086,22 @@ float_opt_is([], Fs, _Count, _Acc) ->
none.
float_make_op(#b_set{op={bif,Op},dst=Dst,args=As0}=I0,
- Ts, #fs{s=S,regs=Rs0}=Fs, Count0) ->
+ Ts, #fs{s=S,regs=Rs0,vars=Vs0}=Fs, Count0) ->
{As1,Rs1,Count1} = float_load(As0, Ts, Rs0, Count0, []),
{As,Is0} = unzip(As1),
{Fr,Count2} = new_reg('@fr', Count1),
FrDst = #b_var{name=Fr},
I = I0#b_set{op={float,Op},dst=FrDst,args=As},
+ Vs = cerl_sets:add_element(Dst, Vs0),
Rs = Rs1#{Dst=>FrDst},
Is = append(Is0) ++ [I],
case S of
undefined ->
{Ignore,Count} = new_reg('@ssa_ignore', Count2),
C = #b_set{op={float,clearerror},dst=#b_var{name=Ignore}},
- {[C|Is],Fs#fs{s=cleared,regs=Rs},Count};
+ {[C|Is],Fs#fs{s=cleared,regs=Rs,vars=Vs},Count};
cleared ->
- {Is,Fs#fs{regs=Rs},Count2}
+ {Is,Fs#fs{regs=Rs,vars=Vs},Count2}
end.
float_load([A|As], [T|Ts], Rs0, Count0, Acc) ->
@@ -1211,34 +1230,31 @@ live_opt_is([#b_set{op=phi,dst=Dst}=I|Is], Live, Acc) ->
false ->
live_opt_is(Is, Live, Acc)
end;
-live_opt_is([#b_set{op=succeeded,dst=SuccDst=SuccDstVar,
- args=[Dst]}=SuccI,
- #b_set{dst=Dst}=I|Is], Live0, Acc) ->
- case gb_sets:is_member(Dst, Live0) of
- true ->
- Live1 = gb_sets:add(Dst, Live0),
- Live = gb_sets:delete_any(SuccDst, Live1),
- live_opt_is([I|Is], Live, [SuccI|Acc]);
- false ->
- case live_opt_unused(I) of
- {replace,NewI0} ->
- NewI = NewI0#b_set{dst=SuccDstVar},
- live_opt_is([NewI|Is], Live0, Acc);
- keep ->
- case gb_sets:is_member(SuccDst, Live0) of
- true ->
- Live1 = gb_sets:add(Dst, Live0),
- Live = gb_sets:delete(SuccDst, Live1),
- live_opt_is([I|Is], Live, [SuccI|Acc]);
- false ->
- live_opt_is([I|Is], Live0, Acc)
- end
- end
+live_opt_is([#b_set{op=succeeded,dst=SuccDst,args=[MapDst]}=SuccI,
+ #b_set{op=get_map_element,dst=MapDst}=MapI | Is],
+ Live0, Acc) ->
+ case {gb_sets:is_member(SuccDst, Live0),
+ gb_sets:is_member(MapDst, Live0)} of
+ {true, true} ->
+ Live = gb_sets:delete(SuccDst, Live0),
+ live_opt_is([MapI | Is], Live, [SuccI | Acc]);
+ {true, false} ->
+ %% 'get_map_element' is unused; replace 'succeeded' with
+ %% 'has_map_field'
+ NewI = MapI#b_set{op=has_map_field,dst=SuccDst},
+ live_opt_is([NewI | Is], Live0, Acc);
+ {false, true} ->
+ %% 'succeeded' is unused (we know it will succeed); discard it and
+ %% keep 'get_map_element'
+ live_opt_is([MapI | Is], Live0, Acc);
+ {false, false} ->
+ live_opt_is(Is, Live0, Acc)
end;
live_opt_is([#b_set{dst=Dst}=I|Is], Live0, Acc) ->
case gb_sets:is_member(Dst, Live0) of
true ->
- Live1 = gb_sets:union(Live0, gb_sets:from_ordset(beam_ssa:used(I))),
+ LiveUsed = gb_sets:from_ordset(beam_ssa:used(I)),
+ Live1 = gb_sets:union(Live0, LiveUsed),
Live = gb_sets:delete(Dst, Live1),
live_opt_is(Is, Live, [I|Acc]);
false ->
@@ -1246,17 +1262,14 @@ live_opt_is([#b_set{dst=Dst}=I|Is], Live0, Acc) ->
true ->
live_opt_is(Is, Live0, Acc);
false ->
- Live = gb_sets:union(Live0, gb_sets:from_ordset(beam_ssa:used(I))),
+ LiveUsed = gb_sets:from_ordset(beam_ssa:used(I)),
+ Live = gb_sets:union(Live0, LiveUsed),
live_opt_is(Is, Live, [I|Acc])
end
end;
live_opt_is([], Live, Acc) ->
{Acc,Live}.
-live_opt_unused(#b_set{op=get_map_element}=Set) ->
- {replace,Set#b_set{op=has_map_field}};
-live_opt_unused(_) -> keep.
-
%%%
%%% Optimize binary matching.
%%%
@@ -1942,6 +1955,10 @@ verify_merge_is(_) ->
is_merge_allowed(_, #b_blk{}, #b_blk{is=[#b_set{op=peek_message}|_]}) ->
false;
+is_merge_allowed(_, #b_blk{}, #b_blk{is=[#b_set{op=exception_trampoline}|_]}) ->
+ false;
+is_merge_allowed(_, #b_blk{is=[#b_set{op=exception_trampoline}|_]}, #b_blk{}) ->
+ false;
is_merge_allowed(L, #b_blk{last=#b_br{}}=Blk, #b_blk{}) ->
%% The predecessor block must have exactly one successor (L) for
%% the merge to be safe.
@@ -2040,6 +2057,7 @@ unsuitable_1([{L,#b_blk{is=[#b_set{op=Op}|_]}}|Bs]) ->
Unsuitable = case Op of
bs_extract -> true;
bs_put -> true;
+ exception_trampoline -> true;
{float,_} -> true;
landingpad -> true;
peek_message -> true;
@@ -2248,6 +2266,8 @@ non_guards(Linear) ->
non_guards_1([{L,#b_blk{is=Is}}|Bs]) ->
case Is of
+ [#b_set{op=exception_trampoline}|_] ->
+ [L | non_guards_1(Bs)];
[#b_set{op=landingpad}|_] ->
[L | non_guards_1(Bs)];
_ ->
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-13 16:48:57 +0000