Sam Clegg

Using wasm globals to represent data/function addresses in object files

12

;tldr; should we use globals hold data addresses, even in non-PIC object files. The current tooling conventions for object files (and the default used by llvm) is to represent data...

Linking.md: Use multiple data and code sections

4

I'd like to propose that we move towards using multple data and code sections in the object format. This matches llvm's internal ideas about what a section is. Today if...

We have various builtin symbols names which we use in the object format and in the final output executable which should be documents in Linking.md. They should also be consistent....

Referencing symbols accross the DLL boundary

5

The current state of dynamic linking is described https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md. However this doesn't detail how imported symbols can referenced. Looking at the current implementation in emscripten it seems that all references...

Linking.md: Handling relocation against external symbols (e.g. imported data symbols)

32

In attempting to switch emscripten over to using the llvm wasm backend + lld we've hit a fairly significant road block. The problem is this: Emscripten allows for functions to...

Linking.md: How should the linker handle non-"env" imports

1

I've got a change out that adds initial support for imports from custom modules: https://reviews.llvm.org/D45796 However I think we should probably handle them a little differently going forward. Perhaps only...

Should we make relocations specific to data segments and individual functions

8

By default in the toolchain we are running with -ffunction-sections and -fdata-sections. In order to achieve this the linker must be able to selectively include or exclude a given data...

_WASI_EMULATED_MMAN is doesn't write changes back to the underlying file

2

The `munmap` is supposed to do this, but also `msync` is completely missing.

_WASI_EMULATED_MMAN: mmap does not return aligned memory

12

The memory returned from mmap is supposed to be page aligned. The file offset passed in is also required to be page aligned.

Today dlmalloc has hardcoded `MALLOC_ALIGNMENT` of 2*pointer size: https://github.com/WebAssembly/wasi-libc/blob/3c4a3f94d1ce685a672ec9a642f1ae42dae16eb1/dlmalloc/src/malloc.c#L628 Emscripten has had the same issue basically forever, but its not standards compliant and is causing issues for some codebases that...