asm.js throwing an exception when hitting an emcripten-generated 'true'/'false'

[Joe Bibbo]

After successfully building and verifying the functionality of a large C++ library, I was noticing that the code was running slower than expected. The browser was putting up a warning about
the emscripten-generated asm.js "Invalid asm.js: Undefined global variable"  I tracked it down to the asm.js code, and any place that the toolchain

had decided to use use a 'true' or 'false' constant. The browser would complain ( chrome, firefox ).

                  .
                  .
                  .
                        c[(F + 48 | 0) + 8 >> 2] = 674;

                               Kk(0, 0, 184863, F + 48 | 0);

                               Eb()

                           }

                           if (true ? (c[m + 8 >> 2] & 32 | 0) == 0 : 0)

                               if ((d[m + 4 >> 0] | 0) < 2)

                                   a = 36;

                               else

                                   a = 37;

                           else

                               a = 36;

                    .
                   

Building on mac,

emcc (Emscripten gcc/clang-like replacement) 1.38.5 (commit a4474e59db658cea570c78254fa71119cf688db5)

Any ideas on what I must do to avoid this type of generated code?

Thanks in advance for any help or advice.

Regards,
Joe

[Alon Zakai]

What options did you compile with? And did you run anything on the JS afterwards?

That code sample looks a little like what closure compiler or another JS minifier might do. In emscripten, building with --closure 2 might lead to similar stuff - but we would disable asm.js validation in that case. If you run a minifier yourself on the output, without disabling that, then an error like this could occur.

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[Joe Bibbo]

Alon,

Brilliant! You are right. I was looking at the output after Webpack got a hold of it.

The output(.js) out of the emscripten tool chain produces clean asmjs code. It is a problem with my packaging tools.

Now, I just a need to figure out how to get Webpack to ignore the embedded asmjs code when merging it. But obviously not an emscripten issue.

Thanks for spotting my problem.

Regards,
Joe

[Alon Zakai]

Cool, glad that was it.

Btw, the --separate-asm option might help here, it emits the asm.js in another file. Another option, if speed is not that important, is to disable asm.js validation (-s ASM_JS=0).