diff options
Diffstat (limited to 'lib/compiler/src/v3_codegen.erl')
| -rw-r--r-- | lib/compiler/src/v3_codegen.erl | 50 |
1 files changed, 28 insertions, 22 deletions
diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl index a96d58a903..a8f4926e55 100644 --- a/lib/compiler/src/v3_codegen.erl +++ b/lib/compiler/src/v3_codegen.erl @@ -1495,28 +1495,34 @@ select_extract_map(Src, Vs, Fail, I, Vdb, Bef, St) -> {Code, Aft, St}. -select_extract_cons(Src, [#k_var{name=Hd}, #k_var{name=Tl}], I, Vdb, Bef, St) -> - {Es,Aft} = case {vdb_find(Hd, Vdb), vdb_find(Tl, Vdb)} of - {{_,_,Lhd}, {_,_,Ltl}} when Lhd =< I, Ltl =< I -> - %% Both head and tail are dead. No need to generate - %% any instruction. - {[], Bef}; - _ -> - %% At least one of head and tail will be used, - %% but we must always fetch both. We will call - %% clear_dead/2 to allow reuse of the register - %% in case only of them is used. - - Reg0 = put_reg(Tl, put_reg(Hd, Bef#sr.reg)), - Int0 = Bef#sr{reg=Reg0}, - Rsrc = fetch_var(Src, Int0), - Rhd = fetch_reg(Hd, Reg0), - Rtl = fetch_reg(Tl, Reg0), - Int1 = clear_dead(Int0, I, Vdb), - {[{get_list,Rsrc,Rhd,Rtl}], Int1} - end, - {Es,Aft,St}. - +select_extract_cons(Src, [#k_var{name=Hd},#k_var{name=Tl}], I, Vdb, Bef, St) -> + Rsrc = fetch_var(Src, Bef), + Int = clear_dead(Bef, I, Vdb), + {{_,_,Lhd},{_,_,Ltl}} = {vdb_find(Hd, Vdb),vdb_find(Tl, Vdb)}, + case {Lhd =< I, Ltl =< I} of + {true,true} -> + %% Both dead. + {[],Bef,St}; + {true,false} -> + %% Head dead. + Reg0 = put_reg(Tl, Bef#sr.reg), + Aft = Int#sr{reg=Reg0}, + Rtl = fetch_reg(Tl, Reg0), + {[{get_tl,Rsrc,Rtl}],Aft,St}; + {false,true} -> + %% Tail dead. + Reg0 = put_reg(Hd, Bef#sr.reg), + Aft = Int#sr{reg=Reg0}, + Rhd = fetch_reg(Hd, Reg0), + {[{get_hd,Rsrc,Rhd}],Aft,St}; + {false,false} -> + %% Both used. + Reg0 = put_reg(Tl, put_reg(Hd, Bef#sr.reg)), + Aft = Bef#sr{reg=Reg0}, + Rhd = fetch_reg(Hd, Reg0), + Rtl = fetch_reg(Tl, Reg0), + {[{get_hd,Rsrc,Rhd},{get_tl,Rsrc,Rtl}],Aft,St} + end. guard_clause_cg(#k_guard_clause{anno=#l{vdb=Vdb},guard=G,body=B}, Fail, Bef, St0) -> {Gis,Int,St1} = guard_cg(G, Fail, Vdb, Bef, St0), |