venti: work around gcc 4.3 bug (reported by Lucho Ionkov)
diff --git a/src/cmd/venti/srv/icache.c b/src/cmd/venti/srv/icache.c
index bf61612..7a528b6 100644
--- a/src/cmd/venti/srv/icache.c
+++ b/src/cmd/venti/srv/icache.c
@@ -15,7 +15,19 @@
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;
