diff options
Diffstat (limited to 'lib/compiler/src/v3_kernel.erl')
| -rw-r--r-- | lib/compiler/src/v3_kernel.erl | 53 |
1 files changed, 47 insertions, 6 deletions
diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl index b184987625..8ef71e1346 100644 --- a/lib/compiler/src/v3_kernel.erl +++ b/lib/compiler/src/v3_kernel.erl @@ -81,7 +81,7 @@ -export([module/2,format_error/1]). -import(lists, [map/2,foldl/3,foldr/3,mapfoldl/3,splitwith/2,member/2, - keymember/3,keyfind/3]). + keymember/3,keyfind/3,partition/2]). -import(ordsets, [add_element/2,del_element/2,union/2,union/1,subtract/2]). -import(cerl, [c_tuple/1]). @@ -1081,9 +1081,44 @@ select_bin_con(Cs0) -> end, Cs0), select_bin_con_1(Cs1). + select_bin_con_1(Cs) -> try - select_bin_int(Cs) + %% The usual way to match literals is to first extract the + %% value to a register, and then compare the register to the + %% literal value. Extracting the value is good if we need + %% compare it more than once. + %% + %% But we would like to combine the extracting and the + %% comparing into a single instruction if we know that + %% a binary segment must contain specific integer value + %% or the matching will fail, like in this example: + %% + %% <<42:8,...>> -> + %% <<42:8,...>> -> + %% . + %% . + %% . + %% <<42:8,...>> -> + %% <<>> -> + %% + %% The first segment must either contain the integer 42 + %% or the binary must end for the match to succeed. + %% + %% The way we do is to replace the generic #k_bin_seg{} + %% record with a #k_bin_int{} record if all clauses will + %% select the same literal integer (except for one or more + %% clauses that will end the binary). + + {BinSegs0,BinEnd} = + partition(fun (C) -> + clause_con(C) =:= k_bin_seg + end, Cs), + BinSegs = select_bin_int(BinSegs0), + case BinEnd of + [] -> BinSegs; + [_|_] -> BinSegs ++ [{k_bin_end,BinEnd}] + end catch throw:not_possible -> select_bin_con_2(Cs) @@ -1097,7 +1132,7 @@ select_bin_con_2([]) -> []. %% select_bin_int([Clause]) -> {k_bin_int,[Clause]} %% If the first pattern in each clause selects the same integer, -%% rewrite all clauses to use #k_bin_int{} (which will later to +%% rewrite all clauses to use #k_bin_int{} (which will later be %% translated to a bs_match_string/4 instruction). %% %% If it is not possible to do this rewrite, a 'not_possible' @@ -1346,7 +1381,7 @@ clause_arg(#iclause{pats=[Arg|_]}) -> Arg. clause_con(C) -> arg_con(clause_arg(C)). -clause_val(C) -> arg_val(clause_arg(C)). +clause_val(C) -> arg_val(clause_arg(C), C). is_var_clause(C) -> clause_con(C) =:= k_var. @@ -1377,7 +1412,7 @@ arg_con(Arg) -> #k_var{} -> k_var end. -arg_val(Arg) -> +arg_val(Arg, C) -> case arg_arg(Arg) of #k_literal{val=Lit} -> Lit; #k_int{val=I} -> I; @@ -1385,7 +1420,13 @@ arg_val(Arg) -> #k_atom{val=A} -> A; #k_tuple{es=Es} -> length(Es); #k_bin_seg{size=S,unit=U,type=T,flags=Fs} -> - {set_kanno(S, []),U,T,Fs} + case S of + #k_var{name=V} -> + #iclause{isub=Isub} = C, + {#k_var{name=get_vsub(V, Isub)},U,T,Fs}; + _ -> + {set_kanno(S, []),U,T,Fs} + end end. %% ubody_used_vars(Expr, State) -> [UsedVar] |