[PATCH] D64322: [WebAssembly] Add support for llvm.clear_cache intrinsic

[Dan Gohman via Phabricator via llvm-commits]

sunfish added a comment.

The actual compiler crash here came from the fact that we don't have an entry for llvm.clear_cache in the builtin function signature table. Suppose we added a signature for it. Then, we'd get LLVM's and compiler-rt's default behavior, which would be to call `__clear_cache`, and ultimately just abort at runtime <https://github.com/llvm/llvm-project/blob/master/compiler-rt/lib/builtins/clear_cache.c#L181>.

So, what if we do `report_fatal_error("llvm.clear_cache is not supported on wasm");` from within `getClearCacheBuiltinName`? That's friendlier than aborting at runtime at least.

I think of wasm as being at the opposite end of the spectrum from x86 in this area. When you write to memory:

- x86: you can execute it immediately, given the right permissions
- arm: you can't execute it until you flush the cache
- wasm: you can't execute it ever


Repository:
  rL LLVM

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  https://reviews.llvm.org/D64322/new/

https://reviews.llvm.org/D64322