From: Simon Marlow <marlowsd@gmail.com>
Date: Wed, 5 Nov 2008 15:03:59 +0000 (+0000)
Subject: retreat the top/bottom fields of the spark pool in pruneSparkPool()
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=840eb5b9b8894281e414d78cdbe037bc7b458e74;p=ghc-hetmet.git

retreat the top/bottom fields of the spark pool in pruneSparkPool()
---

diff --git a/rts/Sparks.c b/rts/Sparks.c
index 8f52a61..38a3090 100644
--- a/rts/Sparks.c
+++ b/rts/Sparks.c
@@ -387,6 +387,13 @@ pruneSparkQueue (evac_fn evac, void *user, Capability *cap)
     
     pool = cap->sparks;
     
+    // Take this opportunity to reset top/bottom modulo the size of
+    // the array, to avoid overflow.  This is only possible because no
+    // stealing is happening during GC.
+    pool->bottom  -= pool->top & ~pool->moduloSize;
+    pool->top     &= pool->moduloSize;
+    pool->topBound = pool->top;
+
     debugTrace(DEBUG_sched,
                "markSparkQueue: current spark queue len=%d; (hd=%ld; tl=%ld)",
                sparkPoolSize(pool), pool->bottom, pool->top);