Allow mapping shared memory to allocate bitsets

[software/dgc/cdgc.git] / rt / gc / cdgc / bits.d

diff --git a/rt/gc/cdgc/bits.d b/rt/gc/cdgc/bits.d
index 275beb622db188445808a8870392d1fff1b32ecd..9a8d1b48a7bdec9ad7fe50ee525defec2090bf2f 100644 (file)
--- a/rt/gc/cdgc/bits.d
+++ b/rt/gc/cdgc/bits.d
@@ -26,7 +26,9 @@
 
 module rt.gc.cdgc.bits;
 
-import rt.gc.cdgc.libc;
+import rt.gc.cdgc.alloc: os_mem_map, os_mem_unmap, Vis;
+
+import cstring = tango.stdc.string;
 
 private extern (C) void onOutOfMemoryError();
 
@@ -59,11 +61,21 @@ struct GCBits
     size_t nwords = 0;    // allocated words in data[] excluding sentinals
     size_t nbits = 0;     // number of bits in data[] excluding sentinals
 
-    void Dtor()
+    /// Get the number of bytes needed to store nbits bits
+    size_t data_size()
+    {
+        return (nwords + 2) * uint.sizeof; // +2 for sentinels
+    }
+
+    void Dtor(Vis vis = Vis.PRIV)
     {
+        // Even when os_mem_unmap() can be called with a null pointer, the
+        // extra call might be significant. On hard GC benchmarks making the
+        // test for null here (i.e. not making the call) can reduce the GC time
+        // by almost ~5%.
         if (data)
         {
-            free(data);
+            os_mem_unmap(data, data_size, vis);
             data = null;
         }
     }
@@ -76,11 +88,11 @@ struct GCBits
         }
     }
 
-    void alloc(size_t nbits)
+    void alloc(size_t nbits, Vis vis = Vis.PRIV)
     {
         this.nbits = nbits;
-        nwords = (nbits + (BITS_PER_WORD - 1)) >> BITS_SHIFT;
-        data = cast(uint*)calloc(nwords + 2, uint.sizeof);
+        this.nwords = (nbits + (BITS_PER_WORD - 1)) >> BITS_SHIFT;
+        this.data = cast(uint*) os_mem_map(data_size, vis);
         if (!data)
             onOutOfMemoryError();
     }
@@ -137,14 +149,13 @@ struct GCBits
             }
         }
         else
-        {   uint result;
-
+        {
             //result = (cast(bit *)(data + 1))[i];
             //(cast(bit *)(data + 1))[i] = 0;
 
             uint* p = &data[1 + (i >> BITS_SHIFT)];
             uint  mask = (1 << (i & BITS_MASK));
-            result = *p & mask;
+            uint result = *p & mask;
             *p &= ~mask;
             return result;
         }
@@ -157,7 +168,7 @@ struct GCBits
             for (;d1!=dEnd;++d1)
                 *d1=0u;
         } else {
-            memset(data + 1, 0, nwords * uint.sizeof);
+            cstring.memset(data + 1, 0, nwords * uint.sizeof);
         }
     }
 
@@ -173,7 +184,7 @@ struct GCBits
             for (;d1!=dEnd;++d1,++d2)
                 *d1=*d2;
         } else {
-            memcpy(data + 1, f.data + 1, nwords * uint.sizeof);
+            cstring.memcpy(data + 1, f.data + 1, nwords * uint.sizeof);
         }
     }
 
@@ -217,3 +228,6 @@ unittest
 
     b.Dtor();
 }
+
+
+// vim: set et sw=4 sts=4 :