Incorrect STACKTOP in asm side modules

[rianhunter]

When emitting an ASM side module, emscripten sets STACKTOP in the shell:

emscripten/src/shell_sharedlib.js

Line 15 in 20602ef

var STACKTOP = getMemory(TOTAL_STACK);

But this STACKTOP variable is overridden when emitting the asm variables in emscripten.py:

emscripten/emscripten.py

Line 489 in 4ce1300

stack += apply_memory(' var STACKTOP = {{{ STACK_BASE }}};\n')

This causes the side module to corrupt memory because its STACKTOP is not the dynamically allocated STACKTOP obtained from the side module shell, and is a lower STACKTOP taken from considering only the globals in the side module.

My fix would be to change the condition in emscripten.py:

emscripten/emscripten.py

Line 487 in 4ce1300

if not (shared.Settings.WASM and shared.Settings.SIDE_MODULE):

But I'm not sure if that is the correct change.

[kripken]

I think for side modules in general, not just asm.js ones, we can't know their stack location at compile time. So yes, I think the fix is to change that condition to not happen for any side module.

[rianhunter]

I came up with a set of changes that seem to be consistent with the surrounding code. The distinction wasn't side modules but "relocatable" modules. Unfortunately two tests are failing, so I'm still investigating that but if you can, let me know if I'm on the right track.