SAFE_HEAP=1 disables proper source code mapping

[cforger]

Hello,

With this command line, I get proper source code mapping in the comments of the .js file output.

emcc -g4 -O0 --js-opts 0 -s FS_LOG=1 -s EMULATE_FUNCTION_POINTER_CASTS=1 -s ASSERTIONS=2 --separate-asm --memory-init-file 1

By adding SAFE_HEAP=1 the source code map is no longer correct

emcc -g4 -O0 --js-opts 0 -s SAFE_HEAP=1 -s FS_LOG=1 -s EMULATE_FUNCTION_POINTER_CASTS=1 -s ASSERTIONS=2 --separate-asm --memory-init-file 1

What I see with this setting is "//@line 70514" which judging by the line# is a reference to the inside of my asm.js file, not the original C source code.

Removing SAFE_HEAP=1 fixes the problem, and I get a proper source map output "//@line 284 "./Modules/sre_lib.h""

Perhaps this is by design? I didn't see mention of this behaviour in the documentation that recommends the use of SAFE_HEAP, so I assume it's a bug.

[kripken]

This does look like a bug. I suspect the issue is that SAFE_HEAP uses js optimizations to apply itself, and those can mess up those annotations.

[cforger]

Great, let me know if I_can assist in it's squashing.

[kripken]

Sure, if you have time to look into this that would be great. I don't really know the source mapping code well myself, so probably whoever looks into it will be learning some new code anyhow ;)

[cforger]

Alright, it may be a bit steep for me considering I'm ~3 days into Emscripten, but I'll see if I can divert the time to it.

[kripken]

If it's tricky, I wouldn't spend much time on it. That's a rare combination of flags. It would be nice to have it work, but I don't see a reason why 2 builds couldn't be almost as good.

[martijnthe]

Maybe related? #5246

[Stuk]

I'm seeing this issue too. My command line is:

-g4 -s ASSERTIONS=2 -s GL_ASSERTIONS=1 -s DEMANGLE_SUPPORT=1 -s SAFE_HEAP=1 -D DEBUG

I've combined these because I would like to get better errors on "segfaults" in dev, but it actually makes it harder to debug in normal cases!

[stale]

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