From c3b60f86c622ba6978564aa059d4d881b9549936 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Thu, 9 Aug 2012 10:38:07 +0200 Subject: beam_utils: Extend live_opt/1 to recalculate live registers in allocs The code generator uses conservative liveness information. Therefore the number of live registers in allocation instructions (such as test_heap/2) may be too high. Use the actual liveness information to lower the number of live register if it's too high. The main reason we want to do this is to enable more optimizations that depend on liveness analysis, such as the beam_bool and beam_dead passes. --- lib/compiler/src/beam_utils.erl | 55 ++++++++++++++++++++++---------- lib/compiler/test/bs_construct_SUITE.erl | 24 ++++++++++++++ 2 files changed, 63 insertions(+), 16 deletions(-) diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl index 0bc9d4cafe..b9c0cd7304 100644 --- a/lib/compiler/src/beam_utils.erl +++ b/lib/compiler/src/beam_utils.erl @@ -668,18 +668,30 @@ live_opt([{bs_add,Fail,[Src1,Src2,_],Dst}=I|Is], Regs0, D, Acc) -> Regs1 = x_live([Src1,Src2], x_dead([Dst], Regs0)), Regs = live_join_label(Fail, D, Regs1), live_opt(Is, Regs, D, [I|Acc]); -live_opt([{bs_init2,Fail,_,_,Live,_,_}=I|Is], _, D, Acc) -> - Regs1 = live_call(Live), - Regs = live_join_label(Fail, D, Regs1), +live_opt([{bs_init2,Fail,Sz,Extra,Live0,Fl,Dst}|Is], Regs0, D, Acc) -> + Regs1 = x_dead([Dst], Regs0), + Live = live_regs(Regs1), + true = Live =< Live0, %Assertion. + Regs2 = live_call(Live), + Regs = live_join_label(Fail, D, Regs2), + I = {bs_init2,Fail,Sz,Extra,Live,Fl,Dst}, live_opt(Is, Regs, D, [I|Acc]); -live_opt([{bs_init_bits,Fail,Src1,_,Live,_,Src2}=I|Is], _, D, Acc) -> - Regs1 = live_call(Live), - Regs2 = x_live([Src1,Src2], Regs1), +live_opt([{bs_init_bits,Fail,Sz,Extra,Live0,Fl,Dst}|Is], Regs0, D, Acc) -> + Regs1 = x_dead([Dst], Regs0), + Live = live_regs(Regs1), + true = Live =< Live0, %Assertion. + Regs2 = live_call(Live), Regs = live_join_label(Fail, D, Regs2), + I = {bs_init_bits,Fail,Sz,Extra,Live,Fl,Dst}, live_opt(Is, Regs, D, [I|Acc]); -live_opt([{bs_append,Fail,Src1,_,Live,_,Src2,_,Dst}=I|Is], _Regs0, D, Acc) -> - Regs1 = x_dead([Dst], x_live([Src1,Src2], live_call(Live))), - Regs = live_join_label(Fail, D, Regs1), +live_opt([{bs_append,Fail,Bits,Extra,Live0,Unit,Src,Fl,Dst}|Is], + Regs0, D, Acc) -> + Regs1 = x_live([Src], x_dead([Dst], Regs0)), + Live = live_regs(Regs1), + true = Live =< Live0, %Assertion. + Regs2 = live_call(Live), + Regs = live_join_label(Fail, D, Regs2), + I = {bs_append,Fail,Bits,Extra,Live,Unit,Src,Fl,Dst}, live_opt(Is, Regs, D, [I|Acc]); live_opt([{bs_private_append,Fail,Src1,_,Src2,_,Dst}=I|Is], Regs0, D, Acc) -> Regs1 = x_live([Src1,Src2], x_dead([Dst], Regs0)), @@ -837,13 +849,24 @@ live_opt([{allocate_heap,_,_,Live}=I|Is], _, D, Acc) -> live_opt([], _, _, Acc) -> Acc. -live_opt_block([{set,[],[],{alloc,Live,_}}=I|Is], _, D, Acc) -> - live_opt_block(Is, live_call(Live), D, [I|Acc]); -live_opt_block([{set,Ds,Ss,Op}=I|Is], Regs0, D, Acc) -> - Regs = case Op of - {alloc,Live,_} -> live_call(Live); - _ -> x_live(Ss, x_dead(Ds, Regs0)) - end, +live_opt_block([{set,Ds,Ss,Op}=I0|Is], Regs0, D, Acc) -> + Regs1 = x_live(Ss, x_dead(Ds, Regs0)), + {I,Regs} = case Op of + {alloc,Live0,Alloc} -> + %% 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(Regs1), + true = Live =< Live0, %Assertion. + I1 = {set,Ds,Ss,{alloc,Live,Alloc}}, + {I1,live_call(Live)}; + _ -> + {I0,Regs1} + end, case Ds of [{x,X}] -> case (not is_live(X, Regs0)) andalso Op =:= move of diff --git a/lib/compiler/test/bs_construct_SUITE.erl b/lib/compiler/test/bs_construct_SUITE.erl index 9ab76449c7..a393aaeffd 100644 --- a/lib/compiler/test/bs_construct_SUITE.erl +++ b/lib/compiler/test/bs_construct_SUITE.erl @@ -360,6 +360,11 @@ in_catch(Config) when is_list(Config) -> ?line <<255>> = small(255, <<1,2,3,4,5,6,7,8,9>>), ?line <<1,2>> = small(<<7,8,9,10>>, 258), ?line <<>> = small(<<1,2,3,4,5>>, <<7,8,9,10>>), + + <<15,240,0,42>> = small2(255, 42), + <<7:20>> = small2(<<1,2,3>>, 7), + <<300:12>> = small2(300, <<1,2,3>>), + <<>> = small2(<<1>>, <<2>>), ok. small(A, B) -> @@ -381,6 +386,25 @@ small(A, B) -> end, <>. +small2(A, B) -> + case begin + case catch <> of + {'EXIT',_} -> <<>>; + ResA0 -> ResA0 + end + end of + ResA -> ok + end, + case begin + case catch <> of + {'EXIT',_} -> <<>>; + ResB0 -> ResB0 + end + end of + ResB -> ok + end, + <>. + nasty_literals(Config) when is_list(Config) -> case erlang:system_info(endian) of big -> -- cgit v1.2.3