"SyntaxError: invalid increment operand" on Firefox

[SBRK]

With emsdk version 1.13 and 1.16, on Firefox 28.0 on Windows, we are getting the following error :
SyntaxError: invalid increment operand

It used to work with an older version of Emscripten.

[SBRK]

Not sure if it will be of any help but here is the line on which we get the error :
http://pastebin.com/6xF2rwqa

[juj]

This gets printed to web console at app startup time? Can you extract the issue into a small test case?

[juj]

Try building with -g2 to get a more readable version of the output that is not minified.

[SBRK]

Yes it does get printed on the console at startup. I'll try to use g2 to get a more precise location of the problem

[SBRK]

Ok there you go :
invoke_viidi(2, i24 | 0, i25 | 0, ++0, 0);

I'll also try to find the corresponding function in our c++ code

[SBRK]

I've got the corresponding function, but the js function does 2000 lines, so it's not exactly ideal to pinpoint the problem :/

[JMLX42]

The corresponding C++ code is here: https://github.com/aerys/minko/blob/master/framework/src/minko/file/EffectParser.cpp#L290

[SBRK]

Another piece of information : there's only one ++0 in all of the generated js file, and replacing it by 1 makes it work on Firefox

[kripken]

Can you either give me a simple command to build that file by itself, or a link to the bitcode file? Either would allow me to reproduce the problem locally.

[JMLX42]

Hello,

here is a link to the bitcode file that should hold the function:

https://dl.dropboxusercontent.com/u/39247193/libminko-framework.a

It's the library for the Minko core framework. You can build it yourself using the following documentation:

http://doc.v3.minko.io/wiki/Compiling_the_SDK_for_HTML5

Regards,

[kripken]

Compiling that bitcode file with -O2 does not produce the bug. Do I need specific flags to build with?

[JMLX42]

thanks for your help!

flags for em++:

-O2 -MMD -MP

flags for emcc:

-O2 --closure 1 -s CLOSURE_ANNOTATIONS=1 -s ERROR_ON_UNDEFINED_SYMBOLS=1 -s DISABLE_EXCEPTION_CACHING=0 -s TOTAL_MEMORY=268435456

[kripken]

I still can't reproduce,

$emcc libminko-framework.a -O2 --closure 1 -s CLOSURE_ANNOTATIONS=1 -s ERROR_ON_UNDEFINED_SYMBOLS=1 -s DISABLE_EXCEPTION_CACHING=0 -s TOTAL_MEMORY=268435456
$node a.out.js
$

Does that fail on your machine?

[warrenseine]

It does work, but this is not a good test :

• the .js output doesn't contain the ++0 (but it definitely does when linked as a final binary)
• node uses v8, and the issue only happens with Firefox

We'll try to isolate the problem.

[JMLX42]

Hello,

the error now happens in Chrome 35 too (did not happen with Chrome 34) with a different message:

"Uncaught ReferenceError: Invalid left-hand side expression in prefix operation"

You can see it live here: http://showcase.minko.io/assimp/index.html

This is now a major problem since our apps won't work in any up-to-date browser.
Any idea how to fix this?

Regards,

[juj]

In previous comment you mentioned that the repro kripken tried did not work. Do you have a full commandline that could be tried that is a good repro?

[JMLX42]

kripken's test only generates the bytecode but it seams the invalid "++0" is added during the compilation of the final JS code.

Here is our command line:

emcc minko-example-cube.bc -o bin/html5/release/minko-example-cube.js -O2 --closure 1 -s CLOSURE_ANNOTATIONS=1 -s ERROR_ON_UNDEFINED_SYMBOLS=1 -s DISABLE_EXCEPTION_CATCHING=0 -s OUTLINING_LIMIT=20000 --memory-init-file 1 --shell-file template.html --preload-file asset

The main problem is that the code base is pretty large and disabling some libraries will make the "++0" disapear without any reason (the problematic code originates from libminko-framework.a which is always the same...).

Here is how we compile everything in HTML5 using Emscripten + Premake:

http://doc.v3.minko.io/wiki/Compiling_the_SDK_for_HTML5

Thanks for your help!

[JMLX42]

For people with the same problem, we currently use a workaround with a Python script called on the generated JS file:

import tempfile, shutil, os, sys

file = sys.argv[1]
temp_file = tempfile.mktemp()
shutil.copyfile(file, temp_file)

with open(file, "wt") as fout:
    with open(temp_file, "rt") as fin:
        for line in fin:
            fout.write(line.replace('++0', '1'))

We use Premake's post-build commands to call "python fix.py invalid-file.js".

Regards,

[kripken]

Can you provide that .bc file in the emcc command 2 comments back? Then I can try it locally.

[JMLX42]

Sure! Here you go:

https://dl.dropboxusercontent.com/u/39247193/minko-example-cube.bc

Thanks again for your help!

[kripken]

Thanks! Ok, I reduced this to a testcase which shows it is an odd bug resulting from a combination of undefined float in an invoke context, so we end up casting twice, +(+0), which turns into ++0 and breaks us. Fixed on incoming.

[JMLX42]

Thanks!