From dce4cbabd1bbfa3a8acc05ae0b2c3a9df17f93d2 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@swtch.com>
Date: Thu, 31 Jul 2008 15:41:54 -0400
Subject: venti: work around gcc 4.3 bug (reported by Lucho Ionkov)

---
 src/cmd/venti/srv/icache.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/cmd/venti/srv/icache.c b/src/cmd/venti/srv/icache.c
index bf61612c..7a528b68 100644
--- a/src/cmd/venti/srv/icache.c
+++ b/src/cmd/venti/srv/icache.c
@@ -15,7 +15,19 @@ struct ICache
 	IHash	*hash;
 	IEntry	*entries;
 	int		nentries;
-	IEntry	free;
+
+	/*
+	* gcc 4.3 inlines the pushfirst loop in initicache,
+	* but the inliner incorrectly deduces that
+	* icache.free.next has a constant value
+	* throughout the loop.  (In fact, pushfirst
+	* assigns to it as ie->prev->next.)
+	* Marking it volatile should avoid this bug.
+	* The speed of linked list operations is dwarfed
+	* by the disk i/o anyway.
+	*/
+	volatile IEntry free;
+
 	IEntry	clean;
 	IEntry	dirty;
 	u32int	maxdirty;
-- 
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