Ok, I could cobble together a surprisingly simple reproducer here: https://github.com/floooh/emsc-calloc-emmalloc-repro
-flto is indeed needed. So the 4 ingredients are: 1. malloc+memset being 'optimized' to a call to calloc via -O1 or better 2. ...where malloc is called through a function pointer 3. ...and emmalloc is used instead of the vanilla allocator 4. ...and -flto must be enabled ...if any of this is missing, it works :D Should I write an Emscripten ticket too? On Tuesday, 6 September 2022 at 18:43:52 UTC+2 Floh wrote: > Part of the mystery can be solved because clang replaces malloc+memset > pairs with a single calloc call (only when optimization is enabled): > > https://www.godbolt.org/z/8r3Ydjs6a > > ...which explains why the problem shows up in release mode, but not debug > mode. > > There still must be something else going on though, because I'm using the > malloc+memset combo all the time together with emmalloc (and I guess the > missing piece is that the malloc call is going through the function > pointer). > > I'll tinker around a bit more with compiler options (but since this is a > library, I cannot dictate what compiler options the code is built with). > > Cheers! > > On Monday, 5 September 2022 at 19:31:17 UTC+2 [email protected] wrote: > >> The other thing this could be related to is LTO. IIUC LTO itself can >> generate calls to buildin functions (such as malloc and calloc) that are >> not present in the original program. Does disabling LTO fix the problem? >> >> On Mon, Sep 5, 2022 at 10:28 AM Sam Clegg <[email protected]> wrote: >> >>> Can you trying building with `-Wl,--trace-symbol=calloc` rather than >>> `LLD_REPORT_UNDEFINED=1` (I guess there are still some issues with that >>> setting). >>> >>> Does the link time error tell you why calloc is being pulled in? (The >>> JS compiler linker errors should do this but they often just say "top level >>> C/C++"). >>> >>> On Sat, Sep 3, 2022 at 6:03 AM Floh <[email protected]> wrote: >>> >>>> I just stumbled over a very weird problem in a new sample for my sokol >>>> headers which includes a non-trivial 3rd party C library - the spine-c >>>> runtime ( >>>> https://github.com/EsotericSoftware/spine-runtimes/tree/4.1/spine-c/spine-c >>>> ) >>>> >>>> When building in release mode (but not in debug mode) the linker >>>> complains about an unresolved 'calloc' call. Adding detailed output >>>> via LLD_REPORT_UNDEFINED=1 I get tons of: >>>> >>>> wasm-ld: error: >>>> /Users/floh/projects/fips-sdks/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/lto/libemmalloc.a(emmalloc.o): >>>> >>>> undefined symbol: calloc >>>> >>>> ... how does that even make sense when emmalloc is supposed to provide >>>> an implementation of calloc... anyway... >>>> >>>> The error goes away when compiling in debug mode (some differences that >>>> come to mind to the release mode is that debug mode doesn't use -flto, and >>>> also doesn't run the closure compiler). >>>> >>>> The problem also goes away when not building with emmalloc. >>>> >>>> Now the weird thing is that the entire code this sample is built from >>>> doesn't appear to call calloc anywhere... and that other samples which >>>> actually use calloc build just fines. >>>> >>>> Has anybody seen a similar problem yet, before I jump myself into the >>>> rabbit hole? :) >>>> >>>> The problematic command line is: >>>> >>>> em++ -s DISABLE_EXCEPTION_CATCHING=1 -fno-exceptions -fno-rtti >>>> -fstrict-aliasing -Wall -Wno-multichar -Wextra -Wno-unknown-pragmas >>>> -Wno-ignored-qualifiers -Wno-long-long -Wno-overloaded-virtual >>>> -Wno-deprecated-writable-strings -Wno-unused-volatile-lvalue >>>> -Wno-inconsistent-missing-override -Wno-warn-absolute-paths >>>> -Wno-expansion-to-defined -flto -O3 -DNDEBUG -s >>>> DISABLE_EXCEPTION_CATCHING=1 --memory-init-file 0 -s >>>> INITIAL_MEMORY=33554432 -s ERROR_ON_UNDEFINED_SYMBOLS=1 -s >>>> NO_EXIT_RUNTIME=1 -s LLD_REPORT_UNDEFINED=1 -s ALLOW_MEMORY_GROWTH=1 -s >>>> USE_WEBGL2=1 -s "MALLOC='emmalloc'" -s NO_FILESYSTEM=1 -s WASM=1 >>>> --shell-file /Users/floh/projects/sokol-samples/webpage/shell.html -O3 >>>> -flto --closure 1 -s ASSERTIONS=0 >>>> sapp/CMakeFiles/spine-sapp.dir/spine-sapp.c.obj >>>> sapp/CMakeFiles/spine-sapp.dir/spine-assets.c.obj -o >>>> /Users/floh/projects/fips-deploy/sokol-samples/sapp-webgl2-wasm-vscode-release/spine-sapp.html >>>> >>>> libs/sokol/libsokol.a libs/spine-c/libspine-c.a libs/stb/libstb.a >>>> libs/util/libfileutil.a fips-cimgui_cimgui/libcimgui.a >>>> >>>> -- >>>> 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 on the web visit >>>> https://groups.google.com/d/msgid/emscripten-discuss/c47cee25-6e4b-4fbe-9f6f-0d7da7e02562n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/emscripten-discuss/c47cee25-6e4b-4fbe-9f6f-0d7da7e02562n%40googlegroups.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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