surprising result with hipe compilation

[Ulf Wiger (AL/EAB)]

I experimented a bit with a recursive-descent parser, and thought
I'd check whether compiling to native code could speed things up:


First, clocking the parse operation without hipe compilation:

41> timer:tc(contract_parser1,read_and_parse,["file_plugin.con"]).
{5860,
 {ok,[{name,"file_server"},
      {vsn,"ubf1.0"},
      {types,[{info,{constant,info},[]},
              {description,{constant,description},[]},
              {services,{constant,services},[]},
              {contract,{constant,contract},[]},
              {file,{prim,string},[]},
              {ls,{constant,ls},[]},
              {files,{tuple,[{constant,files},{list,{prim,file}}]},[]},
              {getFile,{tuple,[{constant,get},{prim,file}]},[]},
              {noSuchFile,{constant,noSuchFile},[]}]},
      {transition,{start,[{input,{prim,ls},[{output,{prim,files},start}]},
                          {input,{prim,getFile},
                                 [{output,{prim,binary},start},
                                  {output,{prim,noSuchFile},stop}]}]}},
      {anystate,[{{prim,info},{prim,string}},
                 {{prim,description},{prim,string}},
                 {{prim,contract},{prim,term}}]}]}}

This was ~2ms slower than the yecc-generated parse module.
(To be expected. It's supposed to be slower.)


Now, compiling the parse module with hipe:

42> c(contract,[native]).
{module,contract}
...
45> timer:tc(contract_parser1,read_and_parse,["file_plugin.con"]).
{16958,
 {ok,[{name,"file_server"},
      {vsn,"ubf1.0"},
      {types,[{info,{constant,info},[]},
              {description,{constant,description},[]},
              {services,{constant,services},[]},
              {contract,{constant,contract},[]},
              {file,{prim,string},[]},
              {ls,{constant,ls},[]},
              {files,{tuple,[{constant,files},{list,{prim,file}}]},[]},
              {getFile,{tuple,[{constant,get},{prim,file}]},[]},
              {noSuchFile,{constant,noSuchFile},[]}]},
      {transition,{start,[{input,{prim,ls},[{output,{prim,files},start}]},
                          {input,{prim,getFile},
                                 [{output,{prim,binary},start},
                                  {output,{prim,noSuchFile},stop}]}]}},
      {anystate,[{{prim,info},{prim,string}},
                 {{prim,description},{prim,string}},
                 {{prim,contract},{prim,term}}]}]}}



Oops! Slight slow-down. Perhaps all those transitions between threaded
and native...? Hipe-compile the module calling the parser:


52> c(contract_parser1,[native]).
{ok,contract_parser1}
53> timer:tc(contract_parser1,read_and_parse,["file_plugin.con"]).
{75,
 {'EXIT',{undef,[{contract_parser1,read_and_parse,["file_plugin.con"]},
                 {timer,tc,3},
                 {erl_eval,expr,3},
                 {erl_eval,exprs,4},
                 {shell,eval_loop,2}]}}}


Oops again! This looks like a bug, or am I missing something?

The source is available upon request.

/Uffe