> You can look at the JS output file to see the extra assertions are
emitted for
> -sASSERTIONS=2. Perhaps diff against a build without that flag. You will
see
> the flag adds stack checks and other things.

I will need guidance as to what to look for. My knowledge of JavaScript is
minimal: I'm a C programmer who finds JS quite confusing.

> Check your full link command - you likely have an -O1 or -O2 or such, in
addition to the -O0.

Nope.

> If that's not it, what is your full link command?

em++ --pre-js /Path/to/kid_node_prerun.js -sMAXIMUM_MEMORY=4000MB
-sEXPORTED_FUNCTIONS=ENV,_main \
-sALLOW_MEMORY_GROWTH -sSTACK_SIZE=4096KB -sNODERAWFS -g --emit-symbol-map
-sASSERTIONS=2 \
-sSAFE_HEAP=1 /Path/to/lsp/kernel.o clu/object_plus.o lsp/lisp.o
/Path/to/lib/webasm/aga_fix.o /Path/to/system/release/kid_support.a
/Path/to/system/release/pskernel_archive.a -o /u/jgd/regimes/webasm/kid.js

I get these warnings:
em++: warning: running limited binaryen optimizations because DWARF info
requested (or indirectly required) [-Wlimited-postlink-optimizations]
warning: no output file specified, not emitting output

Thanks,

John

On Wed, Nov 26, 2025 at 6:52 PM Alon Zakai <[email protected]> wrote:

>
>
> On Wed, Nov 26, 2025 at 6:37 AM John Dallman <[email protected]>
> wrote:
>
>> I'm linking with -sASSERTIONS=2 -O0, but not getting any assertions going
>> off.
>>
>> https://emscripten.org/docs/porting/Debugging.html says, in the DWARF
>> section:
>>
>> Optimization levels above -O1 or -Og increasingly degrade LLVM debug
>> information (as with other architectures), and optimization flags at link
>> time also disable Emscripten’s runtime ASSERTIONS checks.
>>
>>
>> Does -O0 disable ASSERTIONS checks?
>>
>>
> No, it doesn't.
>
> You can look at the JS output file to see the extra assertions are emitted
> for -sASSERTIONS=2. Perhaps diff against a build without that flag. You
> will see the flag adds stack checks and other things.
>
>
>> I get this warning when linking with, or without -O0:
>>
>> em++: warning: running limited binaryen optimizations because DWARF info
>> requested (or indirectly required) [-Wlimited-postlink-optimizations]
>>
>>
>> Which makes me wonder why binaryen optimisations are being done?
>>
>>
> Check your full link command - you likely have an -O1 or -O2 or such, in
> addition to the -O0. If that's not it, what is your full link command?
>
>
>> Thanks very much,
>>
>> John Dallman
>>
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