From 714bebff44076061d0a719c4eda2cfd213b7ac3d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=96mer=20Sinan=20A=C4=9Facan?= <omeragacan@gmail.com>
Date: Thu, 21 Jul 2016 08:07:41 +0000
Subject: Implement unboxed sum primitive type

Summary:
This patch implements primitive unboxed sum types, as described in
https://ghc.haskell.org/trac/ghc/wiki/UnpackedSumTypes.

Main changes are:

- Add new syntax for unboxed sums types, terms and patterns. Hidden
  behind `-XUnboxedSums`.

- Add unlifted unboxed sum type constructors and data constructors,
  extend type and pattern checkers and desugarer.

- Add new RuntimeRep for unboxed sums.

- Extend unarise pass to translate unboxed sums to unboxed tuples right
  before code generation.

- Add `StgRubbishArg` to `StgArg`, and a new type `CmmArg` for better
  code generation when sum values are involved.

- Add user manual section for unboxed sums.

Some other changes:

- Generalize `UbxTupleRep` to `MultiRep` and `UbxTupAlt` to
  `MultiValAlt` to be able to use those with both sums and tuples.

- Don't use `tyConPrimRep` in `isVoidTy`: `tyConPrimRep` is really
  wrong, given an `Any` `TyCon`, there's no way to tell what its kind
  is, but `kindPrimRep` and in turn `tyConPrimRep` returns `PtrRep`.

- Fix some bugs on the way: #12375.

Not included in this patch:

- Update Haddock for new the new unboxed sum syntax.

- `TemplateHaskell` support is left as future work.

For reviewers:

- Front-end code is mostly trivial and adapted from unboxed tuple code
  for type checking, pattern checking, renaming, desugaring etc.

- Main translation routines are in `RepType` and `UnariseStg`.
  Documentation in `UnariseStg` should be enough for understanding
  what's going on.

Credits:

- Johan Tibell wrote the initial front-end and interface file
  extensions.

- Simon Peyton Jones reviewed this patch many times, wrote some code,
  and helped with debugging.

Reviewers: bgamari, alanz, goldfire, RyanGlScott, simonpj, austin,
           simonmar, hvr, erikd

Reviewed By: simonpj

Subscribers: Iceland_jack, ggreif, ezyang, RyanGlScott, goldfire,
             thomie, mpickering

Differential Revision: https://phabricator.haskell.org/D2259
---
 testsuite/tests/unboxedsums/unboxedsums9.hs | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 testsuite/tests/unboxedsums/unboxedsums9.hs

(limited to 'testsuite/tests/unboxedsums/unboxedsums9.hs')

diff --git a/testsuite/tests/unboxedsums/unboxedsums9.hs b/testsuite/tests/unboxedsums/unboxedsums9.hs
new file mode 100644
index 0000000000..79927fc58b
--- /dev/null
+++ b/testsuite/tests/unboxedsums/unboxedsums9.hs
@@ -0,0 +1,26 @@
+{-# LANGUAGE UnboxedSums, UnboxedTuples, MagicHash #-}
+
+module Main where
+
+type UbxBool = (# (# #) | (# #) #)
+
+{-# NOINLINE packBool #-}
+packBool :: UbxBool -> Bool
+packBool (# _ | #) = True
+packBool (# | _ #) = False
+
+{-# NOINLINE unpackBool #-}
+unpackBool :: Bool -> UbxBool
+unpackBool True  = (# (# #) | #)
+unpackBool False = (# | (# #) #)
+
+{-# NOINLINE showUbxBool #-}
+showUbxBool :: UbxBool -> String
+showUbxBool b = show (packBool b)
+
+main :: IO ()
+main = do
+  putStrLn (showUbxBool (unpackBool True))
+  putStrLn (showUbxBool (unpackBool False))
+  putStrLn (show (packBool (# (# #) | #)))
+  putStrLn (show (packBool (# | (# #) #)))
-- 
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