[PATCH] D40559: Run Wasm entrypoint on load

[Nicholas Wilson via Phabricator via llvm-commits]

ncw added a comment.

In https://reviews.llvm.org/D40559#938273, @ruiu wrote:

> I believe you want to report an error when a user passes both --relocatable and --entry.


That's already done by the existing code in `LinkerDriver::link`.

I've added a new test, and updated the existing ones, and I think all the cases are covered now.



================
Comment at: wasm/Driver.cpp:328
+    if (!Config->Entry.empty())
+      addSyntheticUndefinedFunction(Config->Entry);
 
----------------
sbc100 wrote:
> Don't we always want some kind of entry point for non-relocatable binaries.  Without it it will be hard to gc unused functions.   (I suppose we could use the '-u' flag to pin the function we want kept instead?)
I think it makes sense to allow having no entry point. In this case, the only exports will be the (non-hidden) functions defined in the `.o` files, plus the (non-hidden) functions defined in objects that were loaded from any `.a` files.

It would be nice for "completeness" to add a `-u` commandline argument, to allow pulling in symbols from `.a` files that come from translation units we're not otherwise touching.

I'm expecting that 99% of people with a Wasm module will be wanting to export an API consisting of several functions, so the `--entry` argument was never really going to be enough to be useful in the general case for selecting which functions should be exported.

I'll add `-u` support to wasm-lld while I'm at it!



================
Comment at: wasm/Driver.cpp:352
+    if (!Sym)
+      fatal("entry point not found: " + Config->Entry);
     if (!Sym->isFunction())
----------------
sbc100 wrote:
> We probably don't need these two checks here and in Writer.cpp.
Done, I've kept the second checks as an assertion though. (And also added a check for whether Sym is actually defined, fixing a crash.)


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D40559