erlang的内联编译

今天再erlang inline 编译中读到erlang的函数也可以内联编译。
但是内联功能从来不会默认打开的。如果想使用的话，必须显示的在代码里使用-compile()属性。
当再代码里加上-compile(inline).时，编译器会根据自己的规则来决定哪个函数被定义成内联函数，其中有一个因素就是-compile({inline_size, Size}).，默认的size是24，这个size作为一个权重来参与决定某个函数是否被编译成内联的函数。
我们也可以使用
-compile({inline, [test/0, start/1]}).
或者
-compile({inline, [{test, 0}, {start, 1}]}).
来显示的指定哪个函数被编译成内联的函数。
我们还可以使用
-compile(inline_list_funcs).
来显示将下列的函数内联到该模块

引用

         * lists:all/2
         * lists:any/2
         * lists:foreach/2
         * lists:map/2
         * lists:flatmap/2
         * lists:filter/2
         * lists:foldl/3
         * lists:foldr/3
         * lists:mapfoldl/3
         * lists:mapfoldr/3

另外我们也可以同时指定这些选项来编译模块，例如：
-compile([inline, {inline_size, 100}, inline_list_funcs, {inline, [show/0]}]).

下面我们使用一个例子来看一下是否使用内联编译的区别：
[list]

不是用内联编译

erlang文件

-module(test).

-export([test/0, show/0]).

test() -> 
	show(), 
	show(), 
	show(), 
	show().

show() ->
	io:format("this is ~p~n", ["test"]).

生成的汇编代码

{module, test}.  %% version = 0

{exports, [{module_info,0},{module_info,1},{show,0},{test,0}]}.

{attributes, []}.

{labels, 9}.


{function, test, 0, 2}.
  {label,1}.
    {line,[{location,"test.erl",5}]}.
    {func_info,{atom,test},{atom,test},0}.
  {label,2}.
    {allocate,0,0}.
    {line,[{location,"test.erl",6}]}.
    {call,0,{f,4}}.
    {line,[{location,"test.erl",7}]}.
    {call,0,{f,4}}.
    {line,[{location,"test.erl",8}]}.
    {call,0,{f,4}}.
    {call_last,0,{f,4},0}.


{function, show, 0, 4}.
  {label,3}.
    {line,[{location,"test.erl",11}]}.
    {func_info,{atom,test},{atom,show},0}.
  {label,4}.
    {move,{literal,["test"]},{x,1}}.
    {move,{literal,"this is ~p~n"},{x,0}}.
    {line,[{location,"test.erl",12}]}.
    {call_ext_only,2,{extfunc,io,format,2}}.


{function, module_info, 0, 6}.
  {label,5}.
    {line,[]}.
    {func_info,{atom,test},{atom,module_info},0}.
  {label,6}.
    {move,{atom,test},{x,0}}.
    {line,[]}.
    {call_ext_only,1,{extfunc,erlang,get_module_info,1}}.


{function, module_info, 1, 8}.
  {label,7}.
    {line,[]}.
    {func_info,{atom,test},{atom,module_info},1}.
  {label,8}.
    {move,{x,0},{x,1}}.
    {move,{atom,test},{x,0}}.
    {line,[]}.
    {call_ext_only,2,{extfunc,erlang,get_module_info,2}}.

使用内联编译

erlang代码

-module(test).

-export([test/0, show/0]).

-compile([inline, {inline_size, 100}, inline_list_funcs, {inline, [show/0]}]).

test() -> 
	show(), 
	show(), 
	show(), 
	show().

show() ->
	io:format("this is ~p~n", ["test"]).

生成的汇编代码

{module, test}.  %% version = 0

{exports, [{module_info,0},{module_info,1},{show,0},{test,0}]}.

{attributes, []}.

{labels, 9}.


{function, test, 0, 2}.
  {label,1}.
    {line,[{location,"test.erl",9}]}.
    {func_info,{atom,test},{atom,test},0}.
  {label,2}.
    {allocate,0,0}.
    {move,{literal,["test"]},{x,1}}.
    {move,{literal,"this is ~p~n"},{x,0}}.
    {line,[{location,"test.erl",16}]}.
    {call_ext,2,{extfunc,io,format,2}}.
    {move,{literal,["test"]},{x,1}}.
    {move,{literal,"this is ~p~n"},{x,0}}.
    {line,[{location,"test.erl",16}]}.
    {call_ext,2,{extfunc,io,format,2}}.
    {move,{literal,["test"]},{x,1}}.
    {move,{literal,"this is ~p~n"},{x,0}}.
    {line,[{location,"test.erl",16}]}.
    {call_ext,2,{extfunc,io,format,2}}.
    {move,{literal,["test"]},{x,1}}.
    {move,{literal,"this is ~p~n"},{x,0}}.
    {line,[{location,"test.erl",16}]}.
    {call_ext_last,2,{extfunc,io,format,2},0}.


{function, show, 0, 4}.
  {label,3}.
    {line,[{location,"test.erl",15}]}.
    {func_info,{atom,test},{atom,show},0}.
  {label,4}.
    {move,{literal,["test"]},{x,1}}.
    {move,{literal,"this is ~p~n"},{x,0}}.
    {line,[{location,"test.erl",16}]}.
    {call_ext_only,2,{extfunc,io,format,2}}.


{function, module_info, 0, 6}.
  {label,5}.
    {line,[]}.
    {func_info,{atom,test},{atom,module_info},0}.
  {label,6}.
    {move,{atom,test},{x,0}}.
    {line,[]}.
    {call_ext_only,1,{extfunc,erlang,get_module_info,1}}.


{function, module_info, 1, 8}.
  {label,7}.
    {line,[]}.
    {func_info,{atom,test},{atom,module_info},1}.
  {label,8}.
    {move,{x,0},{x,1}}.
    {move,{atom,test},{x,0}}.
    {line,[]}.
    {call_ext_only,2,{extfunc,erlang,get_module_info,2}}.

[/list]
其中生成汇编代码的命令是：
erlc -S test