[Gc] Re: Performance of bdwgc7.2 had degraded compared to6.8 - I think I found a solution/reason

[Manuel.Serrano at inria.fr]

Hi Carsten,

I have tried the following in reclaim.c but I have not noticed any
performance difference between BGL_MEMCPY1, BGL_MEMCPY2, and
default. What have you tried exactly?

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--- gc/bdwgc-7_2alpha5-20110107/reclaim.c       2010-03-05 15:26:16.000000000 +0100
+++ /tmp/reclaim.c      2011-03-05 19:32:05.000000000 +0100
@@ -142,9 +142,25 @@
                       }
 #                   else
                       p++; /* Skip link field */
+#define BGL_MEMCPY1
+#if defined( BGL_MEMCPY1 )
+                     switch ( (q-p) % 4 ) {
+                        while (p < q ) {
+                           case 0: *p++ = 0;
+                           case 1: *p++ = 0;
+                           case 2: *p++ = 0;
+                           case 3: *p++ = 0;
+                        }
+                     }
+#else
+#  if defined( BGL_MEMCPY2 )
+                     memcpy( p, 0, (q-p)*sizeof(p) );
+#  else                      
                       while (p < q) {
                         *p++ = 0;
                       }
+#  endif                     
+#endif               
 #                   endif
             }
             bit_no += MARK_BIT_OFFSET(sz);
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-- 
Manuel
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