From 0971feb23d553bb51b04eb78fbf76c4bc19b4b93 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Tue, 14 Apr 2015 13:01:00 +0200 Subject: v3_codegen: Reduce cost for fixing up bs_match_string instructions Commit b76588fb5a introduced an optimization of the compile time of huge functions with many bs_match_string instructions. The optimization is done in two passes. The first pass coalesces adjacent bs_match_string instructions. To avoid copying bitstrings multiple times, the bitstrings in the instructions are combined in to a (deep) list. The second pass goes through all instructions in the function and combines the list of bitstrings to a single bitstring in all bs_match_string instructions. The second pass (fix_bs_match_string) is run on all instructions in each function, even if there are no bs_match_instructions in the function. While fix_bs_match_string is not a bottleneck (it is a linear pass), its execution time is noticeable when profiling some modules. Move the execution of the second pass to the select_binary() function so that it will only be executed for instructions that do binary matching. Also take the opportunity to optimize away uses of bs_restore2 that occour directly after a bs_save2. That optimimization is currently done in beam_block, but it can be done essentially for free in the same pass that fixes up bs_match_string instructions. --- lib/compiler/src/v3_codegen.erl | 42 +++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) (limited to 'lib/compiler/src/v3_codegen.erl') diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl index eb7926d3ab..15a54a5886 100644 --- a/lib/compiler/src/v3_codegen.erl +++ b/lib/compiler/src/v3_codegen.erl @@ -121,24 +121,15 @@ cg_fun(Les, Hvs, Vdb, AtomMod, NameArity, Anno, St0) -> put_reg(V, Reg) end, [], Hvs), stk=[]}, 0, Vdb), - {B0,_Aft,St} = cg_list(Les, 0, Vdb, Bef, + {B,_Aft,St} = cg_list(Les, 0, Vdb, Bef, St3#cg{bfail=0, ultimate_failure=UltimateMatchFail, is_top_block=true}), - B = fix_bs_match_strings(B0), {Name,Arity} = NameArity, Asm = [{label,Fi},line(Anno),{func_info,AtomMod,{atom,Name},Arity}, {label,Fl}|B++[{label,UltimateMatchFail},if_end]], {Asm,Fl,St}. -fix_bs_match_strings([{test,bs_match_string,F,[Ctx,BinList]}|Is]) - when is_list(BinList) -> - I = {test,bs_match_string,F,[Ctx,list_to_bitstring(BinList)]}, - [I|fix_bs_match_strings(Is)]; -fix_bs_match_strings([I|Is]) -> - [I|fix_bs_match_strings(Is)]; -fix_bs_match_strings([]) -> []. - %% cg(Lkexpr, Vdb, StackReg, State) -> {[Ainstr],StackReg,State}. %% Generate code for a kexpr. %% Split function into two steps for clarity, not efficiency. @@ -717,22 +708,37 @@ select_nil(#l{ke={val_clause,nil,B}}, V, Tf, Vf, Bef, St0) -> select_binary(#l{ke={val_clause,{binary,{var,V}},B},i=I,vdb=Vdb}, V, Tf, Vf, Bef, St0) -> Int0 = clear_dead(Bef#sr{reg=Bef#sr.reg}, I, Vdb), - {Bis,Aft,St1} = match_cg(B, Vf, Int0, St0), + {Bis0,Aft,St1} = match_cg(B, Vf, Int0, St0), CtxReg = fetch_var(V, Int0), Live = max_reg(Bef#sr.reg), - {[{test,bs_start_match2,{f,Tf},Live,[CtxReg,V],CtxReg}, - {bs_save2,CtxReg,{V,V}}|Bis], - Aft,St1}; + Bis1 = [{test,bs_start_match2,{f,Tf},Live,[CtxReg,V],CtxReg}, + {bs_save2,CtxReg,{V,V}}|Bis0], + Bis = finish_select_binary(Bis1), + {Bis,Aft,St1}; select_binary(#l{ke={val_clause,{binary,{var,Ivar}},B},i=I,vdb=Vdb}, V, Tf, Vf, Bef, St0) -> Regs = put_reg(Ivar, Bef#sr.reg), Int0 = clear_dead(Bef#sr{reg=Regs}, I, Vdb), - {Bis,Aft,St1} = match_cg(B, Vf, Int0, St0), + {Bis0,Aft,St1} = match_cg(B, Vf, Int0, St0), CtxReg = fetch_var(Ivar, Int0), Live = max_reg(Bef#sr.reg), - {[{test,bs_start_match2,{f,Tf},Live,[fetch_var(V, Bef),Ivar],CtxReg}, - {bs_save2,CtxReg,{Ivar,Ivar}}|Bis], - Aft,St1}. + Bis1 = [{test,bs_start_match2,{f,Tf},Live,[fetch_var(V, Bef),Ivar],CtxReg}, + {bs_save2,CtxReg,{Ivar,Ivar}}|Bis0], + Bis = finish_select_binary(Bis1), + {Bis,Aft,St1}. + +finish_select_binary([{bs_save2,R,Point}=I,{bs_restore2,R,Point}|Is]) -> + [I|finish_select_binary(Is)]; +finish_select_binary([{bs_save2,R,Point}=I,{test,is_eq_exact,_,_}=Test, + {bs_restore2,R,Point}|Is]) -> + [I,Test|finish_select_binary(Is)]; +finish_select_binary([{test,bs_match_string,F,[Ctx,BinList]}|Is]) + when is_list(BinList) -> + I = {test,bs_match_string,F,[Ctx,list_to_bitstring(BinList)]}, + [I|finish_select_binary(Is)]; +finish_select_binary([I|Is]) -> + [I|finish_select_binary(Is)]; +finish_select_binary([]) -> []. %% New instructions for selection of binary segments. -- cgit v1.2.3