From 8f47436d4941e7871569e47bf8c2f5a6180bdbd5 Mon Sep 17 00:00:00 2001
From: "simonpj@microsoft.com" <unknown>
Date: Thu, 20 Dec 2007 17:34:32 +0000
Subject: [PATCH] Remove obselete code for update-in-place (which we no longer
 do)

---
 compiler/main/StaticFlags.hs      |    2 --
 compiler/simplCore/SimplUtils.lhs |   31 ++++---------------------------
 2 files changed, 4 insertions(+), 29 deletions(-)

diff --git a/compiler/main/StaticFlags.hs b/compiler/main/StaticFlags.hs
index 31b9414..a244544 100644
--- a/compiler/main/StaticFlags.hs
+++ b/compiler/main/StaticFlags.hs
@@ -59,7 +59,6 @@ module StaticFlags (
 	opt_UF_UseThreshold,
 	opt_UF_FunAppDiscount,
 	opt_UF_KeenessFactor,
-	opt_UF_UpdateInPlace,
 	opt_UF_DearOp,
 
 	-- Related to linking
@@ -328,7 +327,6 @@ opt_UF_CreationThreshold	= lookup_def_int "-funfolding-creation-threshold"  (45:
 opt_UF_UseThreshold		= lookup_def_int "-funfolding-use-threshold"	   (8::Int)	-- Discounts can be big
 opt_UF_FunAppDiscount		= lookup_def_int "-funfolding-fun-discount"	   (6::Int)	-- It's great to inline a fn
 opt_UF_KeenessFactor		= lookup_def_float "-funfolding-keeness-factor"	   (1.5::Float)
-opt_UF_UpdateInPlace		= lookUp  FSLIT("-funfolding-update-in-place")
 
 opt_UF_DearOp   = ( 4 :: Int)
 			
diff --git a/compiler/simplCore/SimplUtils.lhs b/compiler/simplCore/SimplUtils.lhs
index cff659d..6ce29a2 100644
--- a/compiler/simplCore/SimplUtils.lhs
+++ b/compiler/simplCore/SimplUtils.lhs
@@ -95,10 +95,8 @@ data SimplCont
 	Bool		-- True <=> There is something interesting about
 			--          the context, and hence the inliner
 			--	    should be a bit keener (see interestingCallContext)
-			-- Two cases:
-			-- (a) This is the RHS of a thunk whose type suggests
-			--     that update-in-place would be possible
-			-- (b) This is an argument of a function that has RULES
+			-- Specifically:
+			--     This is an argument of a function that has RULES
 			--     Inlining the call might allow the rule to fire
 
   | CoerceIt 		-- C `cast` co
@@ -156,10 +154,10 @@ mkBoringStop :: OutType -> SimplCont
 mkBoringStop ty = Stop ty AnArg False
 
 mkLazyArgStop :: OutType -> Bool -> SimplCont
-mkLazyArgStop ty has_rules = Stop ty AnArg (canUpdateInPlace ty || has_rules)
+mkLazyArgStop ty has_rules = Stop ty AnArg has_rules
 
 mkRhsStop :: OutType -> SimplCont
-mkRhsStop ty = Stop ty AnRhs (canUpdateInPlace ty)
+mkRhsStop ty = Stop ty AnRhs False
 
 -------------------
 contIsRhsOrArg (Stop {})       	 = True
@@ -400,27 +398,6 @@ interestingArgContext fn call_cont
     go (StrictBind {})	      = False	-- ??
     go (CoerceIt _ c)	      = go c
     go (Stop _ _ interesting) = interesting
-
--------------------
-canUpdateInPlace :: Type -> Bool
--- Consider   let x = <wurble> in ...
--- If <wurble> returns an explicit constructor, we might be able
--- to do update in place.  So we treat even a thunk RHS context
--- as interesting if update in place is possible.  We approximate
--- this by seeing if the type has a single constructor with a
--- small arity.  But arity zero isn't good -- we share the single copy
--- for that case, so no point in sharing.
-
-canUpdateInPlace ty 
-  | not opt_UF_UpdateInPlace = False
-  | otherwise
-  = case splitTyConApp_maybe ty of 
-	Nothing		-> False 
-	Just (tycon, _) -> case tyConDataCons_maybe tycon of
-				Just [dc]  -> arity == 1 || arity == 2
-				           where
-					      arity = dataConRepArity dc
-				other -> False
 \end{code}
 
 
-- 
1.7.10.4