From: simonmar <unknown>
Date: Thu, 1 Mar 2001 14:27:22 +0000 (+0000)
Subject: [project @ 2001-03-01 14:27:22 by simonmar]
X-Git-Tag: Approximately_9120_patches~2505
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=6934a650f1d58e5621699991f2cbea44e2f2e6e7;p=ghc-hetmet.git

[project @ 2001-03-01 14:27:22 by simonmar]
don't needlessly duplicate a binder.
---

diff --git a/ghc/compiler/stgSyn/CoreToStg.lhs b/ghc/compiler/stgSyn/CoreToStg.lhs
index a5e0e85..b59411d 100644
--- a/ghc/compiler/stgSyn/CoreToStg.lhs
+++ b/ghc/compiler/stgSyn/CoreToStg.lhs
@@ -295,9 +295,11 @@ coreToStgExpr (Case scrut bndr alts)
     lookupLiveVarsForSet alts_fvs		`thenLne` \ alts_lvs ->
     let
 	-- determine whether the default binder is dead or not
-	bndr' = bndr `setIdOccInfo` occ_info
-	occ_info | bndr `elementOfFVInfo` alts_fvs = NoOccInfo
-		 | otherwise			   = IAmDead
+	-- This helps the code generator to avoid generating an assignment
+	-- for the case binder (is extremely rare cases) ToDo: remove.
+	bndr'= if (bndr `elementOfFVInfo` alts_fvs) 
+		  then bndr
+		  else bndr `setIdOccInfo` IAmDead
 
 	 -- for a _ccall_GC_, some of the *arguments* need to live across the
 	 -- call (see findLiveArgs comments.), so we annotate them as being live