Move expansion of strings in binaries to v3_core

This speeds up the compilation of binary literals
with string values in them. For example, compiling
a file with a ~340kB binary would yield the following
times by the compiler:

    Compiling "foo"
     parse_module       :   0.130 s    5327.6 kB
     transform_module   :   0.000 s    5327.6 kB
     lint_module        :   0.011 s    5327.8 kB
     expand_module      :   0.508 s   71881.2 kB
     v3_core            :   0.463 s      11.5 kB

Notice the increase in memory and processing time
in expand_module and v3_core. This happened because
expand_module would expand the string in binaries
into chars. For example, the binary <<"foo">>, which
is represented as

    {bin, 1, [
      {bin_element, 1, {string, 1, "foo"}, default, default}
    ]}

would be converted to

    {bin, 1, [
      {bin_element, 1, {char, 1, $f}, default, default},
      {bin_element, 1, {char, 1, $o}, default, default},
      {bin_element, 1, {char, 1, $o}, default, default}
    ]}

However, v3_core would then traverse all of those
characters and convert it into an actual binary, as it
is a literal value.

This patch addresses this issue by moving the expansion
of string into chars to v3_core and only if a literal
value cannot not be built. This reduces the compilation
time of the file mentioned above to the values below:

    Compiling "bar"
     parse_module       :   0.134 s    5327.6 kB
     transform_module   :   0.000 s    5327.6 kB
     lint_module        :   0.005 s    5327.8 kB
     expand_module      :   0.000 s    5328.7 kB
     v3_core            :   0.013 s      11.2 kB

7 files changed, 53 insertions, 25 deletions

diff --git a/lib/compiler/src/sys_pre_expand.erl b/lib/compiler/src/sys_pre_expand.erl
index 7ab4e1845c..f996a2d2d7 100644
--- a/lib/compiler/src/sys_pre_expand.erl
+++ b/lib/compiler/src/sys_pre_expand.erl
@@ -520,9 +520,8 @@ new_fun_name(#expand{func=F,arity=A,fcount=I}=St, FName) ->
 
 %% pattern_bin([Element], State) -> {[Element],[Variable],[UsedVar],State}.
 
-pattern_bin(Es0, St) ->
-    Es1 = bin_expand_strings(Es0),
-    foldr(fun (E, Acc) -> pattern_element(E, Acc) end, {[],St}, Es1).
+pattern_bin(Es, St) ->
+    foldr(fun (E, Acc) -> pattern_element(E, Acc) end, {[],St}, Es).
 
 pattern_element({bin_element,Line,Expr0,Size0,Type0}, {Es,St0}) ->
     {Expr1,St1} = pattern(Expr0, St0),
@@ -558,9 +557,8 @@ coerce_to_float(E, _) -> E.
     
 %% expr_bin([Element], State) -> {[Element],State}.
 
-expr_bin(Es0, St) ->
-    Es1 = bin_expand_strings(Es0),
-    foldr(fun (E, Acc) -> bin_element(E, Acc) end, {[],St}, Es1).
+expr_bin(Es, St) ->
+    foldr(fun (E, Acc) -> bin_element(E, Acc) end, {[],St}, Es).
 
 bin_element({bin_element,Line,Expr,Size,Type}, {Es,St0}) ->
     {Expr1,St1} = expr(Expr, St0),
@@ -570,14 +568,6 @@ bin_element({bin_element,Line,Expr,Size,Type}, {Es,St0}) ->
     {Size2,Type1} = make_bit_type(Line, Size1, Type),
     {[{bin_element,Line,Expr1,Size2,Type1}|Es],St2}.
 
-bin_expand_strings(Es) ->
-    foldr(fun ({bin_element,Line,{string,_,S},Sz,Ts}, Es1) ->
-                  foldr(fun (C, Es2) ->
-                                [{bin_element,Line,{char,Line,C},Sz,Ts}|Es2]
-                        end, Es1, S);
-              (E, Es1) -> [E|Es1]
-          end, [], Es).
-
 %% new_var_name(State) -> {VarName,State}.
 
 new_var_name(St) ->
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index d71411de80..634ec68736 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -901,7 +901,7 @@ try_after(As, St0) ->
 expr_bin(Es0, Anno, St0) ->
     case constant_bin(Es0) of
 	error ->
-	    {Es,Eps,St} = expr_bin_1(Es0, St0),
+	    {Es,Eps,St} = expr_bin_1(bin_expand_strings(Es0), St0),
 	    {#ibinary{anno=#a{anno=Anno},segments=Es},Eps,St};
 	Bin ->
 	    {#c_literal{anno=Anno,val=Bin},[],St0}
@@ -923,7 +923,8 @@ constant_bin(Es) ->
 constant_bin_1(Es) ->
     verify_suitable_fields(Es),
     EmptyBindings = erl_eval:new_bindings(),
-    EvalFun = fun({integer,_,I}, B) -> {value,I,B};
+    EvalFun = fun({string,_,S}, B) -> {value,S,B};
+		 ({integer,_,I}, B) -> {value,I,B};
 		 ({char,_,C}, B) -> {value,C,B};
 		 ({float,_,F}, B) -> {value,F,B};
 		 ({atom,_,undefined}, B) -> {value,undefined,B}
@@ -944,6 +945,9 @@ verify_suitable_fields([{bin_element,_,Val,SzTerm,Opts}|Es]) ->
     end,
     {unit,Unit} = keyfind(unit, 1, Opts),
     case {SzTerm,Val} of
+	{{atom,_,undefined},{string,_,_}} ->
+	    %% UTF-8/16/32.
+	    ok;
 	{{atom,_,undefined},{char,_,_}} ->
 	    %% UTF-8/16/32.
 	    ok;
@@ -983,6 +987,14 @@ count_bits(Int) ->
 count_bits_1(0, Bits) -> Bits;
 count_bits_1(Int, Bits) -> count_bits_1(Int bsr 64, Bits+64).
 
+bin_expand_strings(Es) ->
+    foldr(fun ({bin_element,Line,{string,_,S},Sz,Ts}, Es1) ->
+		  foldr(fun (C, Es2) ->
+				[{bin_element,Line,{char,Line,C},Sz,Ts}|Es2]
+			end, Es1, S);
+	      (E, Es1) -> [E|Es1]
+	  end, [], Es).
+
 expr_bin_1(Es, St) ->
     foldr(fun (E, {Ces,Esp,St0}) ->
 		  {Ce,Ep,St1} = bitstr(E, St0),
@@ -1394,6 +1406,9 @@ bc_elem_size({bin,_,El}, St0) ->
 bc_elem_size(_, _) ->
     throw(impossible).
 
+bc_elem_size_1([{bin_element,_,{string,_,String},{integer,_,N},Flags}|Es], Bits, Vars) ->
+    {unit,U} = keyfind(unit, 1, Flags),
+    bc_elem_size_1(Es, Bits+U*N*length(String), Vars);
 bc_elem_size_1([{bin_element,_,_,{integer,_,N},Flags}|Es], Bits, Vars) ->
     {unit,U} = keyfind(unit, 1, Flags),
     bc_elem_size_1(Es, Bits+U*N, Vars);
@@ -1513,6 +1528,9 @@ bc_list_length(_, _) ->
 bc_bin_size({bin,_,Els}) ->
     bc_bin_size_1(Els, 0).
 
+bc_bin_size_1([{bin_element,_,{string,_,String},{integer,_,Sz},Flags}|Els], N) ->
+    {unit,U} = keyfind(unit, 1, Flags),
+    bc_bin_size_1(Els, N+U*Sz*length(String));
 bc_bin_size_1([{bin_element,_,_,{integer,_,Sz},Flags}|Els], N) ->
     {unit,U} = keyfind(unit, 1, Flags),
     bc_bin_size_1(Els, N+U*Sz);
@@ -1736,7 +1754,7 @@ pat_alias_map_pairs_1([]) -> [].
 
 %% pat_bin([BinElement], State) -> [BinSeg].
 
-pat_bin(Ps, St) -> [pat_segment(P, St) || P <- Ps].
+pat_bin(Ps, St) -> [pat_segment(P, St) || P <- bin_expand_strings(Ps)].
 
 pat_segment({bin_element,L,Val,Size,[Type,{unit,Unit}|Flags]}, St) ->
     Anno = lineno_anno(L, St),
diff --git a/lib/compiler/test/bs_bincomp_SUITE.erl b/lib/compiler/test/bs_bincomp_SUITE.erl
index 4743821337..dd1d245f88 100644
--- a/lib/compiler/test/bs_bincomp_SUITE.erl
+++ b/lib/compiler/test/bs_bincomp_SUITE.erl
@@ -56,6 +56,7 @@ end_per_group(_GroupName, Config) ->
 byte_aligned(Config) when is_list(Config) ->
     cs_init(),
     <<"abcdefg">> = cs(<< <<(X+32)>> || <<X>> <= <<"ABCDEFG">> >>),
+    <<"AxyzBxyzCxyz">> = cs(<< <<X, "xyz">> || <<X>> <= <<"ABC">> >>),
     <<1:32/little,2:32/little,3:32/little,4:32/little>> =
 	cs(<< <<X:32/little>> || <<X:32>> <= <<1:32,2:32,3:32,4:32>> >>),
     cs(<<1:32/little,2:32/little,3:32/little,4:32/little>> =
diff --git a/lib/compiler/test/bs_utf_SUITE.erl b/lib/compiler/test/bs_utf_SUITE.erl
index c894041f72..ef3fc54b37 100644
--- a/lib/compiler/test/bs_utf_SUITE.erl
+++ b/lib/compiler/test/bs_utf_SUITE.erl
@@ -235,6 +235,7 @@ utf32_to_unicode(<<>>) -> [].
 literals(Config) when is_list(Config) ->
     abc_utf8 = match_literal(<<"abc"/utf8>>),
     abc_utf8 = match_literal(<<$a,$b,$c>>),
+    abc_utf8 = match_literal(<<$a/utf8,$b/utf8,$c/utf8>>),
 
     abc_utf16be = match_literal(<<"abc"/utf16>>),
     abc_utf16be = match_literal(<<$a:16,$b:16,$c:16>>),
diff --git a/lib/debugger/src/dbg_iload.erl b/lib/debugger/src/dbg_iload.erl
index 369b456524..f83684b605 100644
--- a/lib/debugger/src/dbg_iload.erl
+++ b/lib/debugger/src/dbg_iload.erl
@@ -216,7 +216,7 @@ pattern({op,_,'-',{float,Anno,I}}) ->
 pattern({op,_,'+',{float,Anno,I}}) ->
     {value,ln(Anno),I};
 pattern({bin,Anno,Grp}) ->
-    Grp1 = pattern_list(Grp),
+    Grp1 = pattern_list(bin_expand_strings(Grp)),
     {bin,ln(Anno),Grp1};
 pattern({bin_element,Anno,Expr,Size,Type}) ->
     Expr1 = pattern(Expr),
@@ -297,7 +297,7 @@ gexpr({map,Anno,E0,Fs0}) ->
     Fs1 = map_fields(Fs0, fun gexpr/1),
     {map,ln(Anno),E1,Fs1};
 gexpr({bin,Anno,Flds0}) ->
-    Flds = gexpr_list(Flds0),
+    Flds = gexpr_list(bin_expand_strings(Flds0)),
     {bin,ln(Anno),Flds};
 gexpr({bin_element,Anno,Expr0,Size0,Type}) ->
     Expr = gexpr(Expr0),
@@ -506,7 +506,7 @@ expr({op,Anno,Op,L0,R0}, _Lc) ->
     R1 = expr(R0, false),		  %They see the same variables
     {op,ln(Anno),Op,[L1,R1]};
 expr({bin,Anno,Grp}, _Lc) ->
-    Grp1 = expr_list(Grp),
+    Grp1 = expr_list(bin_expand_strings(Grp)),
     {bin,ln(Anno),Grp1};
 expr({bin_element,Anno,Expr,Size,Type}, _Lc) ->
     Expr1 = expr(Expr, false),
@@ -519,6 +519,19 @@ consify([A|As]) ->
     {cons,0,A,consify(As)};
 consify([]) -> {value,0,[]}.
 
+%% The debugger converts both strings "abc" and lists [67, 68, 69]
+%% into {value, Line, [67, 68, 69]}, making it impossible to later
+%% distingish one or the other inside binaries when evaluating. To
+%% avoid <<[67, 68, 69]>> from evaluating, we convert strings into
+%% chars to avoid the ambiguity.
+bin_expand_strings(Es) ->
+    lists:foldr(fun ({bin_element,Line,{string,_,S},Sz,Ts}, Es1) ->
+		  lists:foldr(fun (C, Es2) ->
+				[{bin_element,Line,{char,Line,C},Sz,Ts}|Es2]
+			end, Es1, S);
+	      (E, Es1) -> [E|Es1]
+	  end, [], Es).
+
 %% -type expr_list([Expression]) -> [Expression].
 %%  These expressions are processed "in parallel" for purposes of variable
 %%  definition etc.
diff --git a/lib/debugger/test/bs_bincomp_SUITE.erl b/lib/debugger/test/bs_bincomp_SUITE.erl
index 39e2240f2d..064e9567b3 100644
--- a/lib/debugger/test/bs_bincomp_SUITE.erl
+++ b/lib/debugger/test/bs_bincomp_SUITE.erl
@@ -66,6 +66,7 @@ end_per_group(_GroupName, Config) ->
 
 byte_aligned(Config) when is_list(Config) ->
     <<"abcdefg">> = << <<(X+32)>> || <<X>> <= <<"ABCDEFG">> >>,
+    <<"AxyzBxyzCxyz">> = << <<X, "xyz">> || <<X>> <= <<"ABC">> >>,
     <<1:32/little,2:32/little,3:32/little,4:32/little>> =
 	<< <<X:32/little>> || <<X:32>> <= <<1:32,2:32,3:32,4:32>> >>,
     <<1:32/little,2:32/little,3:32/little,4:32/little>> =
diff --git a/lib/stdlib/src/eval_bits.erl b/lib/stdlib/src/eval_bits.erl
index 80667023fb..631faa3be5 100644
--- a/lib/stdlib/src/eval_bits.erl
+++ b/lib/stdlib/src/eval_bits.erl
@@ -67,16 +67,20 @@ expr_grp([Field | FS], Bs0, Lf, Acc) ->
 expr_grp([], Bs0, _Lf, Acc) ->
     {value,Acc,Bs0}.
 
+eval_field({bin_element, _, {string, _, S}, {integer,_,8}, [integer,{unit,1},unsigned,big]}, Bs0, _Fun) ->
+    Latin1 = [C band 16#FF || C <- S],
+    {list_to_binary(Latin1),Bs0};
 eval_field({bin_element, _, {string, _, S}, default, default}, Bs0, _Fun) ->
     Latin1 = [C band 16#FF || C <- S],
     {list_to_binary(Latin1),Bs0};
-eval_field({bin_element, Line, {string, _, S}, Size0, Options0}, Bs, _Fun) ->
-    {_Size,[Type,_Unit,_Sign,Endian]} = 
+eval_field({bin_element, Line, {string, _, S}, Size0, Options0}, Bs0, Fun) ->
+    {Size1,[Type,{unit,Unit},Sign,Endian]} =
         make_bit_type(Line, Size0, Options0),
-    Res = << <<(eval_exp_field1(C, no_size, no_unit,
-				Type, Endian, no_sign))/binary>> ||
+    {value,Size,Bs1} = Fun(Size1, Bs0),
+    Res = << <<(eval_exp_field1(C, Size, Unit,
+				Type, Endian, Sign))/binary>> ||
 	      C <- S >>,
-    {Res,Bs};
+    {Res,Bs1};
 eval_field({bin_element,Line,E,Size0,Options0}, Bs0, Fun) ->
     {value,V,Bs1} = Fun(E, Bs0),
     {Size1,[Type,{unit,Unit},Sign,Endian]} =