[PATCH] D42867: [WebAssembly] Add _edata, _end and other link-sythentic symbols

[Sam Clegg via Phabricator via llvm-commits]

sbc100 added a comment.

In https://reviews.llvm.org/D42867#996838, @sunfish wrote:

> Is there a use for `_edata`? I'm curious how applications would use it differently from `_end`.
>
> Is there a way for applications to determine where the data starts? Traditionally that might be something like `_etext`, but of course that doesn't apply to wasm. Could they get it from `__bss_start` and/or `__heap_base`? What's the relationship between those symbols?


Maybe nobody will need `_edata`.   I added it mostly for completeness.   The current `DataSize` we have in the linker meta section will be replaced by `_end`, and that is needed by emscripten.

There is no way to determine where the data starts, no.   We could put `_etext` there, but it seems a little strange to have `_etext`.

I think __bss_start will normally be the same as _edata on wasm (modulo alignment of the first bss symbol I guess?.     I just realized I forgot to add __bss_start here.

__heap_base follows data + bss + stack.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D42867