[PATCH] D106525: [WebAssembly] Make Emscripten EH work with Emscripten SjLj

[Heejin Ahn via Phabricator via llvm-commits]

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When Emscripten EH mixes with Emscripten SjLj, we are not currently
handling some of them correctly. There are three cases:

1. The current function calls `setjmp` and there is an `invoke` to a function that can either throw or longjmp. In this case, we have to check both for exception and longjmp. We are currently handling this case correctly: https://github.com/llvm/llvm-project/blob/0c0eb76782d5224b8d81a5afbb9a152bcf7c94c7/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp#L1058-L1090 When inserting routines for functions that can longjmp, which we do only for setjmp-calling functions, we check if the function was previously an `invoke` and handle it correctly.

2. The current function does NOT call `setjmp` and there is an `invoke` to a function that can either throw or longjmp. Because there is no `setjmp` call, we haven't been doing any check for functions that can longjmp. But in that case, for `invoke`, we only check for an exception and if it is not an exception we reset `__THREW__` to 0, which can silently swallow the longjmp: https://github.com/llvm/llvm-project/blob/0c0eb76782d5224b8d81a5afbb9a152bcf7c94c7/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp#L70-L80 This CL fixes this.

3. The current function calls `setjmp` and there is no `invoke`. Because it is not an `invoke`, we haven't been doing any check for functions that can throw, and only insert longjmp-checking routines for functions that can longjmp. But in that case, if a longjmpable function throws, we only check for a longjmp so if it is not a longjmp we reset `__THREW__` to 0, which can silently swallow the exception: https://github.com/llvm/llvm-project/blob/0c0eb76782d5224b8d81a5afbb9a152bcf7c94c7/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp#L156-L169 This CL fixes this.

To do that, this moves around some code, so we register necessary
functions for both EH and SjLj and precompute some data (the set of
functions that contains `setjmp`) before doing actual EH or SjLj
transformation.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D106525

Files:
  llvm/lib/Target/WebAssembly/WebAssembly.h
  llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
  llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll
  llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll

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