Erlang HiPE

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HiPE(High Performance Erlang) 霸爷有一个一语中的的描述"erlang的hipe相当于jit, 根据语言评测有hipe支持在纯erlang的运算上会快2-3倍，这个性能的提升对于计算密集型的应用还是比较可观的。"

编译启用HIPE选项可以这样:c(Module,[native,{hipe,HipeOptions}|MoreOptions). 或者在Emakefile添加对应的配置节;

关于hipe选项的可用参数,我们可以通过hipe:help_options()查看,下面是在我机器上的执行结果:

Erlang R14B03 (erts-5.8.4) [source] [64-bit] [smp:2:2] [rq:2] [async-threads:0] [hipe] [kernel-poll:false]Eshell V5.8.4  (abort with ^G)1> hipe:help_options().HiPE Compiler Options Boolean-valued options generally have corresponding aliases `no_...', and can also be specified as `{Option, true}' or `{Option, false}. General boolean options:   [debug,load,pp_asm,pp_beam,pp_icode,pp_native,pp_rtl,time,timeout,verbose]. Non-boolean options:   o#, where 0 =< # =< 3:     Select optimization level (the default is 2). Further options can be found below; use `hipe:help_option(Name)' for details. Aliases:   pp_all = [pp_beam,pp_icode,pp_rtl,pp_native],   pp_sparc = pp_native,   pp_x86 = pp_native,   pp_amd64 = pp_native,   pp_ppc = pp_native,   o0,   o1 = [inline_fp,pmatch,peephole],   o2 = [icode_range,icode_ssa_const_prop,icode_ssa_copy_prop,icode_type,         icode_inline_bifs,rtl_lcm,rtl_ssa,rtl_ssa_const_prop,spillmin_color,         use_indexing,remove_comments,concurrent_comp,binary_opt] ++ o1,   o3 = [{regalloc,coalescing},icode_range] ++ o2.ok

Note: another option is to compile your Erlang module to native code. Native code compiling is not available for every platform and OS, but on those that support it, it can make your programs go faster (about 20% faster, based on anecdotal evidence). To compile to native code, you need to use the hipe module and call it the following way: hipe:c(Module,OptionsList). You could also use c(Module,[{hipe,o3}]).when in the shell to achieve similar results. Note that the .beam file generated will no longer be portable across platforms like regular ones.

All you wanted to know

上面这幅图来自: All you wanted to know about the HiPE compiler [PDF]

启用了HiPE的Erlang/OTP编译流程大体如下:

宏替换代码解析语法糖等助记符展开(比如record)
Erlang Code ==> Core Erlang Code
在Core Erlang层面会完成各种优化比如常数合并,内联函数展开.所谓常数合并,是指在编译时,就将源程序中常数表达式之值先行算出,而不必生成用于计算该常数表达式的代码.例如,可将表达式a+2*3翻译成a+6.这种常数合并在语法制导翻译时就可以完成. [Link] 内联函数之前有一篇相关的[Erlang 0029] Erlang Inline编译
Core Erlang Code ==> BEAM virtual machine code
每个方法的BEAM代码首先被翻译成为ICode,ICode是具有高级功能语义的类汇编语言.
优化之后ICode翻译成RTL("register-transfer language" 一种底层类RISC的汇编语言).
大多数Erlang运算在本次转换过程会转换成为机器运算指令.优化完成之后RTL代码翻译成实际的机器码.许多临时变量会映射到硬件寄存器和运行时堆栈.
最后,代码加载到运行时环境.

Erlang/OTP运行时并存两种代码BEAM-code和native-code 这两种代码的互相调用由运行时负责适配,对用户这是透明的.

Core Erlang 1.0.3 language speciﬁcation [Link] 之前已经多次通过查看Core Erlang代码的方式去分析问题，还是颇有用的。

转自：http://www.cnblogs.com/me-sa/archive/2012/10/09/erlang_hipe.html

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