Incorrect pretty output ptr*

[Ptival]

Encountered some incorrect roundtripping. Here is a fairly minimal reproducer:

define i32 @f(ptr noundef %0) #0 {
  %2 = alloca ptr, align 8
  store ptr %0, ptr %2, align 8
  ret i32 0
}

Assembling to bitcode, parsing with llvm-pretty-bc-parser and then pretty-printing with ppModule yields:

source_filename = "./mini.ll"
target triple = "unknown-unknown-unknown-unknown-"
define default i32 @f(ptr %0) {
; <label>: 1
  %2 = alloca ptr, align 8
  store ptr %0, ptr* %2, align 8
  ret i32 0
}

which contains invalid LLVM IR ptr*. I'm assuming it's a llvm-pretty issue, though it could be the bitcode parser too...

I'm going to try and submit a patch.

[RyanGlScott]

This is an llvm-pretty-bc-parser issue rather than an llvm-pretty one, as the AST itself contains the pointer-to-ptr issue you observe, even before pretty-printing it:

λ> parseBitCodeFromFile "test.bc" >>= pPrint
Right
  Module
    { modSourceName = Just "test.ll"
    , modTriple =
        TargetTriple
          { ttArch = UnknownArch
          , ttSubArch = NoSubArch
          , ttVendor = UnknownVendor
          , ttOS = UnknownOS
          , ttEnv = UnknownEnvironment
          , ttObjFmt = UnknownObjectFormat
          }
    , modDataLayout = []
    , modTypes = []
    , modNamedMd = []
    , modUnnamedMd = []
    , modComdat = fromList []
    , modGlobals = []
    , modDeclares = []
    , modDefines =
        [ Define
            { defLinkage = Nothing
            , defVisibility = Just DefaultVisibility
            , defRetType = PrimType (Integer 32)
            , defName = Symbol "f"
            , defArgs =
                [ Typed { typedType = PtrOpaque , typedValue = Ident "0" } ]
            , defVarArgs = False
            , defAttrs = []
            , defSection = Nothing
            , defGC = Nothing
            , defBody =
                [ BasicBlock
                    { bbLabel = Just (Anon 1)
                    , bbStmts =
                        [ Result (Ident "2") (Alloca PtrOpaque Nothing (Just 8)) []
                        , Effect
                            (Store
                               Typed { typedType = PtrOpaque , typedValue = ValIdent (Ident "0") }
                               Typed
                                 { typedType = PtrTo PtrOpaque , typedValue = ValIdent (Ident "2") }
                               Nothing
                               (Just 8))
                            []
                        , Effect
                            (Ret
                               Typed
                                 { typedType = PrimType (Integer 32) , typedValue = ValInteger 0 })
                            []
                        ]
                    }
                ]
            , defMetadata = fromList []
            , defComdat = Nothing
            }
        ]
    , modInlineAsm = []
    , modAliases = []
    }

(Notice the PtrTo PtrOpaque part, which llvm-pretty faithfully prints as ptr*.)

Would you mind closing this issue and opening a new one on the llvm-pretty-bc-parser repo? I have more thoughts about what is causing this (and how we might fix it), but I'd prefer to do so once we have a proper home for the discussion.

[Ptival]

Moving discussion here.