Thanks. NO_FILESYSTEM is a big help; it reduces the output by about 34k. NO_BROWSER doesn't seem to work, at least with the other options I'm using. When I call the Module function generated by MODULARIZE, it throws an error: "Uncaught ReferenceError: Browser is not defined". So it's removing Browser, but not something else that depends on it. This may not be a good option for C/C++ functions that are to be called from other JavaScript.
I'm still not clear on what --closure 2 requires. Do I need to create a JavaScript externs file and somehow pass that to the Closure compiler? I would have thought that the EXPORTED_FUNCTIONS setting in Emscripten would take care of that. Or maybe there needs to be some other JS file specified with --pre-js or --post-js? On Wednesday, June 24, 2015 at 8:06:57 PM UTC-4, Alon Zakai wrote: > > For --closure 2, the main issue is closure advanced requires special > handing of externs, see > https://developers.google.com/closure/compiler/docs/api-tutorial3 > > See the NO_FILESYSTEM and NO_BROWSER options for reducing code size > further. > > We could add an option to only include code that is explicitly in > EXPORTED_FUNCTIONS, even runtime support. That would take some work though. > But it would be great if it were contributed. > > > > On Wed, Jun 24, 2015 at 11:27 AM, Alan deLespinasse <[email protected] > <javascript:>> wrote: > >> I'm trying to compile a fairly straightforward C library into JavaScript >> so I can use it in Web applications. I've got it working, but I think it's >> larger than it should be. >> >> The library is basically math functions. I just want to call them and get >> their results. They don't do I/O or anything. >> >> As an example, I'll use the int_sqrt function example from the >> documentation >> <http://kripken.github.io/emscripten-site/docs/porting/connecting_cpp_and_javascript/Interacting-with-code.html#calling-compiled-c-functions-from-javascript-using-ccall-cwrap> >> : >> >> >> int int_sqrt(int x) { >> return sqrt(x); >> } >> >> >> Compiling this with -O3 results in an a.out.js file of 143k bytes. I had >> thought that -O3 would automatically run the Closure Compiler to do some >> minification (vaguely implied by the statement that --closure 0 is the >> "default >> in -O2 and below >> <http://kripken.github.io/emscripten-site/docs/tools_reference/emcc.html#emcc-closure>"), >> >> but this doesn't seem to be the case. >> >> After a bit more research, I settled on this command line: >> >> emcc -O3 hello_function.cpp --closure 1 -s >> EXPORTED_FUNCTIONS="['_int_sqrt']" -s MODULARIZE=1 >> >> This gets it down to 80k, a huge improvement, but still rather large for >> such a tiny input. I tried --closure 2, but (a) that only gets it down to >> 77k, and (b) then the code no longer works. I get "Uncaught TypeError: Kc >> is not a function" in the console when I try to call it from JavaScript. >> >> I've seen vague suggestions in various docs that --closure 2 would >> "require modifications to the source". I think there may have been >> something about requiring Closure type annotations. But that doesn't make >> sense to me, since the source code I'm dealing with is C. >> >> So what's actually needed for --closure 2? >> >> Also, looking at the generated code, there seems to be a lot of >> unnecessary stuff, even with --closure 2. For example, I see standard >> library stuff like malloc, free, memset, memcpy, etc. It's true that I >> might want to call those functions from my JavaScript code (in fact, for >> the actual library I'm trying to use, I do need at least malloc and free), >> but I thought I would need to declare such things in the EXPORTED_FUNCTIONS >> variable. >> >> Basically what I'm asking is, is it possible to get the compiled code >> much smaller? >> >> If the answer is "that would require more optimization in Emscripten, >> which we haven't had time to implement yet", then I'm curious what it would >> take. I might consider contributing. (I'm pretty experienced with >> JavaScript, though new to Emscripten.) >> >> -- >> You received this message because you are subscribed to the Google Groups >> "emscripten-discuss" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
