Wrong type when using alloca?

[fduxiao]

As noted in llvm document, the return value of alloca should be a pointer. However, in the process of generating the IR of a Function, it is used with type double:

forM args $ \a -> do
    var <- alloca double
    store var (local (AST.Name a))
    assign a var

That's because the alloca is defined with the instr function:

alloca :: Type -> Codegen Operand
alloca ty = instr $ Alloca ty Nothing 0 []

where instr is defined to be a double reference:

local ::  Name -> Operand
local = LocalReference double

instr :: Instruction -> Codegen (Operand)
instr ins = do
  n <- fresh
  let ref = (UnName n)
  blk <- current
  let i = stack blk
  modifyBlock (blk { stack = (ref := ins) : i } )
  return $ local ref

I found this error when I tried to print the generated IR with llvm-hs-pretty. Even a simple function definition def f(a) a; will trigger this problem with the following generated IR:

GlobalDefinition $ functionDefaults {
    name          = makeName "foo"
    , parameters  = ([Parameter double (makeName "a") []], False)
    , returnType  = double
    , basicBlocks = [
        BasicBlock (makeName "entry") [
            UnName 1 := Alloca double Nothing 0 []
            , UnName 2 := Store False (local $ UnName 1) (local $ makeName "a") Nothing 0 []
            , UnName 3 := Load False (local $ UnName 1) Nothing 0 []
        ] (ret . local $ UnName 3)
    ]
}

I am not sure whether this is some incompatibility with newer version LLVM or this is a fault made by myself, but as suggested by @sdiehl in the repo of llvm-hs-pretty, this should be wrong.