Re: [Haskell-cafe] LLVM, getElementPtr?

5 Dec 2010

      No wait, sorry.

buildReaderFun :: String -> CodeGenModule (Function (IO ()))
buildReaderFun nm = do
  puts <- newNamedFunction ExternalLinkage "puts" :: TFunction (Ptr
Word8 -> IO Word32)
  let callPuts greetz = createFunction ExternalLinkage $ do
          tmp <- getElementPtr greetz (0 :: Word32,(0 :: Word32, ()))
          call puts  tmp -- Throw away return value.
          ret ()
  withStringNul nm callPuts

Is that how it's intended?

Cheers,
-Lally

On Sun, Dec 5, 2010 at 3:35 PM, Lally Singh  wrote:
...
Thanks for your help.  Replying inline
On Sun, Dec 5, 2010 at 1:28 PM, Henning Thielemann
 wrote:
...
On Sun, 5 Dec 2010, Lally Singh wrote:
...
Hey all, I'm trying to get started generating LLVM code, but I'm
getting a rather cryptic error.
Btw. there is haskell-llvm@projects.haskell.org
...
buildReaderFun :: String -> CodeGenModule (Function (IO ()))
buildReaderFun nm = do
 puts <- newNamedFunction ExternalLinkage "puts" :: TFunction (Ptr
Word8 -> IO Word32)
 greetz <- createStringNul nm
 func <- createFunction ExternalLinkage $ do
  tmp <- getElementPtr0 greetz (0 :: Word32, ())
You have to add a type annotation to greetz like
  (greetz :: Array D42 Word8)
 which limits your string to a length of 42 bytes.
If you do not know the length, better use withStringNul.
I implemented the current behavior, because the former implementation was
unsafe.
I'm sorry, the type signature for withStringNul is over my head.
withStringNul ::
  String ->
  (forall n. (Nat n) => Global (Array n Word8) -> CodeGenModule a) ->
  CodeGenModule a
On the LLVM side, I'm looking to simply create a string constant I can
pass in, such as ConstantArray::get(..).
I *think* withStringNul will generate code to build a runtime-length
determined string?   Sorry, I'm a little thick.
...
...
  call puts  tmp -- Throw away return value.
  ret ()
 return func
My attempts at figuring out what type-level has to do with this, and
how to satisfy it have so far proven unsuccessful.
type-level provides type level integers, and thus allows for static checking
of sizes, such as the number of bits of an integer type.
Thanks -- sorry -- I'm guessing it's to make sure we're generating valid code?
Cheers,
-Lally