Good catch Sam, yes, let's avoid the confusing warning when not optimizing:
https://github.com/emscripten-core/emscripten/pull/25889 On Sat, Nov 29, 2025 at 11:59 AM 'Sam Clegg' via emscripten-discuss < [email protected]> wrote: > I think the warning you are seeing might be a little misleading in this > case. > > The reason for the warning is the `-sSAFE_HEAP=1` flag. This flag > requires us to run a binaryen pass over the final output, and currently > whenever we run any binaryen passes, and we also have `-g`, then we issue > this warning. > > Perhaps the warning should be rephrased or downgraded in the case when > optimization is not actually requested. Alon would probably know which > is the best option here. > > Cheers, > sam > > On Thu, Nov 27, 2025 at 6:04 AM John Dallman <[email protected]> > wrote: > >> > 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 >>>> >>>> -- >>>> 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]. >>>> To view this discussion visit >>>> https://groups.google.com/d/msgid/emscripten-discuss/CAH1xqgke4V%3DvuAOACzm2uf8WgKxQhnS9x4fC3-fLV_mKonZcHQ%40mail.gmail.com >>>> <https://groups.google.com/d/msgid/emscripten-discuss/CAH1xqgke4V%3DvuAOACzm2uf8WgKxQhnS9x4fC3-fLV_mKonZcHQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >>> 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]. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/emscripten-discuss/CAEX4NpTc8RSEnCwtS%3De0Cin_sn7pZ18QTvhbO36NASMsmz1SVg%40mail.gmail.com >>> <https://groups.google.com/d/msgid/emscripten-discuss/CAEX4NpTc8RSEnCwtS%3De0Cin_sn7pZ18QTvhbO36NASMsmz1SVg%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> 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]. >> To view this discussion visit >> https://groups.google.com/d/msgid/emscripten-discuss/CAH1xqgm9t_ZU-1p__bZJdGw543RO7UZRWBXW92_KdK%2BY09xGwg%40mail.gmail.com >> <https://groups.google.com/d/msgid/emscripten-discuss/CAH1xqgm9t_ZU-1p__bZJdGw543RO7UZRWBXW92_KdK%2BY09xGwg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > 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]. > To view this discussion visit > https://groups.google.com/d/msgid/emscripten-discuss/CAL_va28s2ddFHAXm%3D-zHCDMzn224WyhCXirF8ru77Vi9dT%3DmJA%40mail.gmail.com > <https://groups.google.com/d/msgid/emscripten-discuss/CAL_va28s2ddFHAXm%3D-zHCDMzn224WyhCXirF8ru77Vi9dT%3DmJA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. 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