diff options
Diffstat (limited to 'lib/compiler')
| -rw-r--r-- | lib/compiler/src/beam_utils.erl | 75 |
1 files changed, 40 insertions, 35 deletions
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl index 7031fe8bfe..814cfb8265 100644 --- a/lib/compiler/src/beam_utils.erl +++ b/lib/compiler/src/beam_utils.erl @@ -1004,47 +1004,52 @@ live_opt([{recv_mark,_}=I|Is], Regs, D, Acc) -> live_opt([], _, _, Acc) -> Acc. -live_opt_block([{set,Ds,Ss,Op0}|Is], Regs0, D, Acc) -> - Regs1 = x_live(Ss, x_dead(Ds, Regs0)), - {Op, Regs} = live_opt_block_op(Op0, Regs1, D), - I = {set, Ds, Ss, Op}, - - case Ds of - [{x,X}] -> - case (not is_live(X, Regs0)) andalso Op =:= move of - true -> - live_opt_block(Is, Regs0, D, Acc); - false -> - live_opt_block(Is, Regs, D, [I|Acc]) - end; - _ -> - live_opt_block(Is, Regs, D, [I|Acc]) +live_opt_block([{set,[{x,X}]=Ds,Ss,move}=I|Is], Regs0, D, Acc) -> + Regs = x_live(Ss, x_dead(Ds, Regs0)), + case is_live(X, Regs0) of + true -> + live_opt_block(Is, Regs, D, [I|Acc]); + false -> + %% Useless move, will never be used. + live_opt_block(Is, Regs, D, Acc) end; -live_opt_block([{'%anno',_}|Is], Regs, D, Acc) -> - live_opt_block(Is, Regs, D, Acc); -live_opt_block([], Regs, _, Acc) -> {Acc,Regs}. - -live_opt_block_op({alloc,Live0,AllocOp}, Regs0, D) -> - Regs = - case AllocOp of - {Kind, _N, Fail} when Kind =:= gc_bif; Kind =:= put_map -> - live_join_label(Fail, D, Regs0); - _ -> - Regs0 - end, +live_opt_block([{set,Ds,Ss,{alloc,Live0,AllocOp}}|Is], Regs0, D, Acc) -> + %% Calculate liveness from the point of view of the GC. + %% There will never be a GC if the instruction fails, so we should + %% ignore the failure branch. + GcRegs1 = x_dead(Ds, Regs0), + GcRegs = x_live(Ss, GcRegs1), + Live = live_regs(GcRegs), %% The life-time analysis used by the code generator is sometimes too %% conservative, so it may be possible to lower the number of live %% registers based on the exact liveness information. The main benefit is %% that more optimizations that depend on liveness information (such as the - %% beam_bool and beam_dead passes) may be applied. - Live = live_regs(Regs), - true = Live =< Live0, - {{alloc,Live,AllocOp}, live_call(Live)}; -live_opt_block_op({bif,_N,Fail} = Op, Regs, D) -> - {Op, live_join_label(Fail, D, Regs)}; -live_opt_block_op(Op, Regs, _D) -> - {Op, Regs}. + %% beam_dead pass) may be applied. + true = Live =< Live0, %Assertion. + I = {set,Ds,Ss,{alloc,Live,AllocOp}}, + + %% Calculate liveness from the point of view of the preceding instruction. + %% The liveness is the union of live registers in the GC and the live + %% registers at the failure label. + Regs1 = live_call(Live), + Regs = live_join_alloc(AllocOp, D, Regs1), + live_opt_block(Is, Regs, D, [I|Acc]); +live_opt_block([{set,Ds,Ss,{bif,_,Fail}}=I|Is], Regs0, D, Acc) -> + Regs1 = x_dead(Ds, Regs0), + Regs2 = x_live(Ss, Regs1), + Regs = live_join_label(Fail, D, Regs2), + live_opt_block(Is, Regs, D, [I|Acc]); +live_opt_block([{set,Ds,Ss,_}=I|Is], Regs0, D, Acc) -> + Regs = x_live(Ss, x_dead(Ds, Regs0)), + live_opt_block(Is, Regs, D, [I|Acc]); +live_opt_block([{'%anno',_}|Is], Regs, D, Acc) -> + live_opt_block(Is, Regs, D, Acc); +live_opt_block([], Regs, _, Acc) -> {Acc,Regs}. + +live_join_alloc({Kind,_Name,Fail}, D, Regs) when Kind =:= gc_bif; Kind =:= put_map -> + live_join_label(Fail, D, Regs); +live_join_alloc(_, _, Regs) -> Regs. live_join_labels([{f,L}|T], D, Regs0) when L =/= 0 -> Regs = gb_trees:get(L, D) bor Regs0, |