[PATCH] D114543: Extend the `uwtable` attribute with unwind table kind

[Momchil Velikov via Phabricator via llvm-commits]

chill added a comment.

In D114543#3319347 <https://reviews.llvm.org/D114543#3319347>, @durin42 wrote:

> As far as I can tell this patch broke the Rust compiler, but from the commit message it sounds like it shouldn't have?
>
> https://buildkite.com/llvm-project/rust-llvm-integrate-prototype/builds/8358#e85ad6f3-9992-4ea1-9cd3-d8db9f45f33e fails with
>
>   Attribute 'uwtable' should have an Argument
>   i8* (i64, i64)* @__rust_alloc
>   in function __rust_alloc
>   LLVM ERROR: Broken function found, compilation aborted!
>
> Any thoughts?

Yeah, that's puzzling. The attribute has an optional argument (or else we had to update ~3080 occurrences  of "uwtable" in tests), so reading it is
a bit tricky:  https://github.com/llvm/llvm-project/blob/19b4e9d76ecc9a5343c093bc54d965734b996518/llvm/lib/Bitcode/Reader/BitcodeReader.cpp#L1631
That message is output here https://github.com/llvm/llvm-project/blob/19b4e9d76ecc9a5343c093bc54d965734b996518/llvm/lib/IR/Verifier.cpp#L1710
and I can trigger this line with

  $ cat x.ll
  define void @f() uwtable {
  	ret void
  }
  $ ./bin/opt -S --passes=verify x.ll
  ; ModuleID = 'x.ll'
  source_filename = "x.ll"
  
  ; Function Attrs: uwtable
  define void @f() #0 {
    ret void
  }
  
  attributes #0 = { uwtable }
  $ ./bin/opt  x.ll -o x.bc
  $ ./bin/opt --verify  x.bc -S
  ; ModuleID = 'x.bc'
  source_filename = "x.ll"
  
  ; Function Attrs: uwtable
  define void @f() #0 {
    ret void
  }
  
  attributes #0 = { uwtable }
  $ 

Could there be a mismatch between two `llvm-project` versions, somehow?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D114543/new/

https://reviews.llvm.org/D114543