From 47c73cc2fb9e89949b60751d9fb6954df88a7b80 Mon Sep 17 00:00:00 2001
From: sof <unknown>
Date: Tue, 9 Sep 1997 18:06:18 +0000
Subject: [PATCH] [project @ 1997-09-09 18:06:18 by sof] new functions:
deadOccurrence, isOneOcc, isOneFunOcc, isOneSafeFunOcc, isDeadOcc; moved:
okToInline (from CoreUnfold)
---
ghc/compiler/simplCore/BinderInfo.lhs | 60 ++++++++++++++++++++-------
1 file changed, 46 insertions(+), 14 deletions(-)
diff --git a/ghc/compiler/simplCore/BinderInfo.lhs b/ghc/compiler/simplCore/BinderInfo.lhs
index 75155a6b745d..39e436d8c31a 100644
--- a/ghc/compiler/simplCore/BinderInfo.lhs
+++ b/ghc/compiler/simplCore/BinderInfo.lhs
@@ -16,12 +16,15 @@ module BinderInfo (
addBinderInfo, orBinderInfo, andBinderInfo,
- argOccurrence, funOccurrence, dangerousArgOcc, noBinderInfo,
+ deadOccurrence, argOccurrence, funOccurrence, dangerousArgOcc, noBinderInfo,
+
markMany, markDangerousToDup, markInsideSCC,
getBinderInfoArity,
setBinderInfoArityToZero,
- inlineUnconditionally, isFun, isDupDanger -- for Simon Marlow deforestation
+ okToInline, isOneOcc, isOneFunOcc, isOneSafeFunOcc, isDeadOcc,
+
+ isFun, isDupDanger -- for Simon Marlow deforestation
) where
IMP_Ubiq(){-uitous-}
@@ -104,6 +107,23 @@ noBinderInfo = ManyOcc 0 -- A non-committal value
\begin{code}
+isOneOcc :: BinderInfo -> Bool
+isOneOcc (OneOcc _ _ _ _ _) = True
+isOneOcc other_bind = False
+
+isOneFunOcc :: BinderInfo -> Bool
+isOneFunOcc (OneOcc FunOcc _ _ _ _) = True
+isOneFunOcc other_bind = False
+
+isOneSafeFunOcc :: Bool -> BinderInfo -> Bool
+isOneSafeFunOcc ok_to_dup (OneOcc FunOcc NoDupDanger NotInsideSCC n_alts _)
+ = ok_to_dup || n_alts <= 1
+isOneSafeFunOcc ok_to_dup other_bind = False
+
+isDeadOcc :: BinderInfo -> Bool
+isDeadOcc DeadCode = True
+isDeadOcc other = False
+
isFun :: FunOrArg -> Bool
isFun FunOcc = True
isFun _ = False
@@ -113,26 +133,38 @@ isDupDanger DupDanger = True
isDupDanger _ = False
\end{code}
-@inlineUnconditionally@ decides whether a let-bound thing can
-definitely be inlined.
\begin{code}
-inlineUnconditionally :: Bool -> BinderInfo -> Bool
-
---inlineUnconditionally ok_to_dup DeadCode = True
-inlineUnconditionally ok_to_dup (OneOcc FunOcc NoDupDanger NotInsideSCC n_alt_occs _)
- = n_alt_occs <= 1 || ok_to_dup
- -- We [i.e., Patrick] don't mind the code explosion,
- -- though. We could have a flag to limit the
- -- damage, e.g., limit to M alternatives.
-
-inlineUnconditionally _ _ = False
+okToInline :: Bool -- The thing is WHNF or bottom;
+ -> Bool -- It's small enough to duplicate the code
+ -> BinderInfo
+ -> Bool -- True <=> inline it
+
+-- A non-WHNF can be inlined if it doesn't occur inside a lambda,
+-- and occurs exactly once or
+-- occurs once in each branch of a case and is small
+okToInline False small_enough (OneOcc _ NoDupDanger _ n_alts _)
+ = n_alts <= 1 || small_enough
+
+-- If the thing isn't a redex, there's no danger of duplicating work,
+-- so we can inline if it occurs once, or is small
+okToInline True small_enough occ_info
+ = small_enough || one_occ
+ where
+ one_occ = case occ_info of
+ OneOcc _ _ _ n_alts _ -> n_alts <= 1
+ other -> False
+
+okToInline whnf_or_bot small_enough any_occ = False
\end{code}
Construction
~~~~~~~~~~~~~
\begin{code}
+deadOccurrence :: BinderInfo
+deadOccurrence = DeadCode
+
argOccurrence, funOccurrence :: Int -> BinderInfo
funOccurrence = OneOcc FunOcc NoDupDanger NotInsideSCC 1
--
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