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-rw-r--r--lib/compiler/src/v3_kernel.erl55
1 files changed, 48 insertions, 7 deletions
diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl
index b184987625..5f1c108f7c 100644
--- a/lib/compiler/src/v3_kernel.erl
+++ b/lib/compiler/src/v3_kernel.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 1999-2012. All Rights Reserved.
+%% Copyright Ericsson AB 1999-2013. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -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]