From 4d55ca70f87151bbf941b0aed24e0cc64361e42a Mon Sep 17 00:00:00 2001
From: simonpj <unknown>
Date: Tue, 24 Aug 1999 09:37:11 +0000
Subject: [PATCH] [project @ 1999-08-24 09:37:11 by simonpj] IdInfo.copyIdInfo
was wrong. It didn't copy a NOINLINE pragma when the occurrenc analyser
"shorted out" a binding; as a result the following program didn't respect the
NOINLINE pragma:
plus :: Int -> Int -> Int
{-# NOINLINE plus #-}
plus = (+)
f x = plus x (plus x x)
---
ghc/compiler/basicTypes/IdInfo.lhs | 41 ++++++++++++++----------------
1 file changed, 19 insertions(+), 22 deletions(-)
diff --git a/ghc/compiler/basicTypes/IdInfo.lhs b/ghc/compiler/basicTypes/IdInfo.lhs
index 48597a5aebee..ac1ef78bac4c 100644
--- a/ghc/compiler/basicTypes/IdInfo.lhs
+++ b/ghc/compiler/basicTypes/IdInfo.lhs
@@ -175,7 +175,7 @@ zapSpecPragInfo info = case flavourInfo info of
copyIdInfo :: IdInfo -- From
-> IdInfo -- To
- -> IdInfo -- To updated with stuff from From; except flavour unchanged
+ -> IdInfo -- To, updated with stuff from From; except flavour unchanged
-- copyIdInfo is used when shorting out a top-level binding
-- f_local = BIG
-- f = f_local
@@ -186,30 +186,20 @@ copyIdInfo :: IdInfo -- From
-- The fact that things can go wrong here is a bad sign, but I can't see
-- how to make it 'patently right', so copyIdInfo is derived (pretty much) by trial and error
--
--- Here 'from' is f_local, 'to' is f.
+-- Here 'from' is f_local, 'to' is f, and the result is attached to f
copyIdInfo from to = from { flavourInfo = flavourInfo to,
- specInfo = specInfo to
+ specInfo = specInfo to,
+ inlinePragInfo = inlinePragInfo to
}
- -- It's important to propagate the inline pragmas from bndr
- -- to exportd_id. Ditto strictness etc. This "bites" when we use an INLNE pragma:
- -- {-# INLINE f #-}
- -- f x = (x,x)
+ -- It's important to preserve the inline pragma on 'f'; e.g. consider
+ -- {-# NOINLINE f #-}
+ -- f = local
--
- -- This becomes (where the "*" means INLINE prag)
+ -- similarly, transformation rules may be attached to f
+ -- and we want to preserve them.
--
- -- M.f = /\a -> let mf* = \x -> (x,x) in mf
- --
- -- Now the mf floats out and we end up with the trivial binding
- --
- -- mf* = /\a -> \x -> (x,x)
- -- M.f = mf
- --
- -- Now, when we short out the M.f = mf binding we must preserve the inline
- -- pragma on the mf binding.
- --
- -- On the other hand, transformation rules may be attached to the
- -- 'to' Id, and we want to preserve them.
+ -- On the other hand, we want the strictness info from f_local.
\end{code}
@@ -284,8 +274,15 @@ besides the code-generator need arity info!)
\begin{code}
data ArityInfo
= UnknownArity -- No idea
- | ArityExactly Int -- Arity is exactly this
- | ArityAtLeast Int -- Arity is this or greater
+
+ | ArityExactly Int -- Arity is exactly this. We use this when importing a
+ -- function; it's already been compiled and we know its
+ -- arity for sure.
+
+ | ArityAtLeast Int -- Arity is this or greater. We attach this arity to
+ -- functions in the module being compiled. Their arity
+ -- might increase later in the compilation process, if
+ -- an extra lambda floats up to the binding site.
seqArity :: ArityInfo -> ()
seqArity a = arityLowerBound a `seq` ()
--
GitLab