emsdk/upstream/emscripten/system/lib/README.md

Source code for C/C++ system libraries
======================================

This directory contains the source code for libc, libc++ and other C/C++ system
libraries.  Where possible these are clones of upstream projects (e.g. musl).
For more details about each library see the individual readme files in the
subdirectories.

Static constructor ordering
---------------------------

These are several static constructors in the emscripten system libraries and they
are in a specific order.  When adding/remove/updating these please update this
document.

These current set of static constructors in system libraries and their priorities
(lowest run first) are:

- 1: `emscripten_stack_init` (stack_limits.S)
- 47: `initialize_emmalloc_heap` (emmalloc.c)
- 48: `__emscripten_init_main_thread` (pthread/library_pthread.c)
- 49: `init_file_data` (generated by file_packager.py)
- 50: asan init (??)
- 100: `WasmFS wasmFS` (wasmfs/wasmfs.cpp)

Priorities 0 - 100 are reserved for system libraries and user-level
constructors should all run at 101 and above (for example libc++ initializes
its standard I/O streams at priority 101).