From 633b02c1f8ef85d46e206af169f8500472ed5269 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 4 Dec 2017 06:02:59 +0100 Subject: beam_dead: Improve creation of select_val from is_eq_exact When converting a comparison BIF (such as '=:=') to a test instruction, run the other optimizations on the result. When trying to combine is_eq_exact tests, handle the case that is_eq_exact is followed by a jump instead of a label to handle a test that has been newly converted from a BIF. Taken together, those changes will coalesce more is_eq_exact instructions into select_val instructions. --- lib/compiler/src/beam_dead.erl | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) (limited to 'lib/compiler/src') diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index d379fdc4eb..1b152a2d6f 100644 --- a/lib/compiler/src/beam_dead.erl +++ b/lib/compiler/src/beam_dead.erl @@ -272,7 +272,8 @@ backward([{jump,{f,To0}},{move,Src,Reg}=Move|Is], D, Acc) -> end; backward([{jump,{f,To}}=J|[{bif,Op,{f,BifFail},Ops,Reg}|Is]=Is0], D, Acc) -> try replace_comp_op(To, Reg, Op, Ops, D) of - I -> backward(Is, D, I++Acc) + {Test,Jump} -> + backward([Jump,Test|Is], D, Acc) catch throw:not_possible -> case To =:= BifFail of @@ -446,7 +447,7 @@ prune_redundant([], _) -> []. replace_comp_op(To, Reg, Op, Ops, D) -> False = comp_op_find_shortcut(To, Reg, {atom,false}, D), True = comp_op_find_shortcut(To, Reg, {atom,true}, D), - [bif_to_test(Op, Ops, False),{jump,{f,True}}]. + {bif_to_test(Op, Ops, False),{jump,{f,True}}}. comp_op_find_shortcut(To0, Reg, Val, D) -> case shortcut_select_label(To0, Reg, Val, D) of @@ -483,15 +484,22 @@ not_possible() -> throw(not_possible). %% F1: is_eq_exact F2 Reg Lit2 F1: is_eq_exact F2 Reg Lit2 %% L2: .... L2: %% -combine_eqs(To, [Reg,{Type,_}=Lit1]=Ops, D, [{label,L1}|_]) - when Type =:= atom; Type =:= integer -> +combine_eqs(To, [Reg,{Type,_}=Lit1]=Ops, D, Acc) + when Type =:= atom; Type =:= integer -> + Next = case Acc of + [{label,Lbl}|_] -> Lbl; + [{jump,{f,Lbl}}|_] -> Lbl + end, case beam_utils:code_at(To, D) of [{test,is_eq_exact,{f,F2},[Reg,{Type,_}=Lit2]}, {label,L2}|_] when Lit1 =/= Lit2 -> - {select,select_val,Reg,{f,F2},[Lit1,{f,L1},Lit2,{f,L2}]}; + {select,select_val,Reg,{f,F2},[Lit1,{f,Next},Lit2,{f,L2}]}; + [{test,is_eq_exact,{f,F2},[Reg,{Type,_}=Lit2]}, + {jump,{f,L2}}|_] when Lit1 =/= Lit2 -> + {select,select_val,Reg,{f,F2},[Lit1,{f,Next},Lit2,{f,L2}]}; [{select,select_val,Reg,{f,F2},[{Type,_}|_]=List0}|_] -> List = remove_from_list(Lit1, List0), - {select,select_val,Reg,{f,F2},[Lit1,{f,L1}|List]}; + {select,select_val,Reg,{f,F2},[Lit1,{f,Next}|List]}; _Is -> {test,is_eq_exact,{f,To},Ops} end; -- cgit v1.2.3