[all-commits] [llvm/llvm-project] d1cd2c: [WebAssembly] Unify type checking in AsmTypeCheck ...

[Heejin Ahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d1cd2c3a26106a8d0e39db3749449261c53cc4e5
      https://github.com/llvm/llvm-project/commit/d1cd2c3a26106a8d0e39db3749449261c53cc4e5
  Author: Heejin Ahn <aheejin at gmail.com>
  Date:   2024-09-26 (Thu, 26 Sep 2024)

  Changed paths:
    M llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
    M llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp
    M llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.h
    M llvm/test/MC/WebAssembly/type-checker-errors.s
    M llvm/test/MC/WebAssembly/type-checker-return.s

  Log Message:
  -----------
  [WebAssembly] Unify type checking in AsmTypeCheck (#110094)

This unifies the way we check types in various places in AsmTypeCheck.
The objectives of this PR are:

- We now use `checkTypes` for all type checking and `checkAndPopTypes`
for type checking + popping. All other functions are helper functions to
call these two functions.

- We now support comparisons of types between vectors. This lets us
printing error messages in more readable way. When an instruction takes
[i32, i64] but the stack top is [f32, f64], now instead of
  ```console
  error: type mismatch, expected i64 but got f64
  error: type mismatch, expected i32 but got f32
  ```
  we can print this
  ```console
  error: type mismatch, expected [i32, i64] but got [f32, f64]
  ```
which is also the format Wabt checker prints. This also helps printing
more meaningful messages when there are superfluous values on the stack
at the end of the function, such as:
  ```console
  error: type mismatch, expected [] but got [i32, exnref]
  ```
Actually, many instructions are not utilizing this batch printing now,
which still causes multiple error messages to be printed for a single
instruction. This will be improved in a follow-up.

- The value stack now supports `Any` and `Ref`. There are instructions
that requires the type to be anything. Also instructions like
`ref.is_null` requires the type to be any reference types. Type
comparison function will handle this types accordingly, meaning
`match(I32, Any)` or `match(externref, Ref)` will succeed.

The changes in `type-checker-errors.s` are mostly the message format
changes. One downside of the new message format is that it doesn't have
instruction names in it. I plan to improve that in a potential
follow-up.

This also made some modifications in the instructions in
`type-checker-errors.s`. Currently, except for a few functions I've
recently added at the end, each function tests for a single error,
because the type checker used to bail out after the first error until
#109705. But many functions included multiple errors anyway, which I
don't think was the intention of the original writer. So I added some
instructions to remove the other errors which are not being tested. (In
some cases I added more error checking lines instead, when I felt that
could be relevant.)

Thanks to the new `ExactMatch` option in `checkTypes` function family,
we now can distinguish the cases when to check against only the top of
the value stack and when to check against the whole stack (e.g. to check
whether we have any superfluous values remaining at the end of the
function). `return` or `return_call(_indirect)` can set `ExactMatch` to
`false` because they don't care about the superfluous values. This makes
`type-checker-return.s` succeed and I was able to remove the `FIXME`.

This is the basis of the PR that fixes block parameter/return type
handling in the checker, but does not yet include the actual
block-related functionality, which will be submitted separately after
this PR.



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