]> git.llucax.com Git - software/dgc/cdgc.git/blobdiff - rt/gc/cdgc/gc.d
Improve variable names for block attributes
[software/dgc/cdgc.git] / rt / gc / cdgc / gc.d
index 1e95f061b1895a035a83e25f9876f6ae28d5cc87..b9973b81a8079ed5bb33f4f0a7c476c153faadd8 100644 (file)
@@ -31,8 +31,6 @@ module rt.gc.cdgc.gc;
 /************** Debugging ***************************/
 
 //debug = COLLECT_PRINTF;       // turn on printf's
-//debug = MEMSTOMP;             // stomp on memory
-//debug = SENTINEL;             // add underrun/overrrun protection
 //debug = PTRCHECK;             // more pointer checking
 //debug = PTRCHECK2;            // thorough but slow pointer checking
 
@@ -45,12 +43,30 @@ version = STACKGROWSDOWN;       // growing the stack means subtracting from the
 /***************************************************/
 
 import rt.gc.cdgc.bits: GCBits;
-import rt.gc.cdgc.stats: GCStats;
+import rt.gc.cdgc.stats: GCStats, Stats;
+import rt.gc.cdgc.dynarray: DynArray;
 import alloc = rt.gc.cdgc.alloc;
+import opts = rt.gc.cdgc.opts;
 
 import cstdlib = tango.stdc.stdlib;
 import cstring = tango.stdc.string;
 
+/*
+ * This is a small optimization that proved it's usefulness. For small chunks
+ * or memory memset() seems to be slower (probably because of the call) that
+ * simply doing a simple loop to set the memory.
+ */
+void memset(void* dst, int c, size_t n)
+{
+    // This number (32) has been determined empirically
+    if (n > 32) {
+        cstring.memset(dst, c, n);
+        return;
+    }
+    auto p = cast(ubyte*)(dst);
+    while (n-- > 0)
+        *p++ = c;
+}
 
 version (GNU)
 {
@@ -61,7 +77,6 @@ version (GNU)
     static import gcc.builtins; // for __builtin_unwind_int
 }
 
-
 struct BlkInfo
 {
     void*  base;
@@ -69,15 +84,16 @@ struct BlkInfo
     uint   attr;
 }
 
+package enum BlkAttr : uint
+{
+    FINALIZE = 0b0000_0001,
+    NO_SCAN  = 0b0000_0010,
+    NO_MOVE  = 0b0000_0100,
+    ALL_BITS = 0b1111_1111
+}
+
 private
 {
-    enum BlkAttr : uint
-    {
-        FINALIZE = 0b0000_0001,
-        NO_SCAN  = 0b0000_0010,
-        NO_MOVE  = 0b0000_0100,
-        ALL_BITS = 0b1111_1111
-    }
 
     extern (C) void* rt_stackBottom();
     extern (C) void* rt_stackTop();
@@ -120,6 +136,8 @@ class GCLock { }                // just a dummy so we can get a global lock
 const uint GCVERSION = 1;       // increment every time we change interface
                                 // to GC.
 
+Stats stats;
+
 class GC
 {
     // For passing to debug code
@@ -134,23 +152,14 @@ class GC
 
     void initialize()
     {
+        opts.parse(cstdlib.getenv("D_GC_OPTS"));
         gcLock = GCLock.classinfo;
         gcx = cast(Gcx*) cstdlib.calloc(1, Gcx.sizeof);
         if (!gcx)
             onOutOfMemoryError();
         gcx.initialize();
         setStackBottom(rt_stackBottom());
-    }
-
-
-    void Dtor()
-    {
-        if (gcx)
-        {
-            gcx.Dtor();
-            cstdlib.free(gcx);
-            gcx = null;
-        }
+        stats = Stats(this);
     }
 
 
@@ -201,15 +210,15 @@ class GC
         uint go()
         {
             Pool* pool = gcx.findPool(p);
-            uint  oldb = 0;
+            uint  old_attrs = 0;
 
             if (pool)
             {
-                auto biti = cast(size_t)(p - pool.baseAddr) / 16;
+                auto bit_i = cast(size_t)(p - pool.baseAddr) / 16;
 
-                oldb = gcx.getBits(pool, biti);
+                old_attrs = gcx.getAttr(pool, bit_i);
             }
-            return oldb;
+            return old_attrs;
         }
 
         if (!thread_needLock())
@@ -236,16 +245,16 @@ class GC
         uint go()
         {
             Pool* pool = gcx.findPool(p);
-            uint  oldb = 0;
+            uint  old_attrs = 0;
 
             if (pool)
             {
-                auto biti = cast(size_t)(p - pool.baseAddr) / 16;
+                auto bit_i = cast(size_t)(p - pool.baseAddr) / 16;
 
-                oldb = gcx.getBits(pool, biti);
-                gcx.setBits(pool, biti, mask);
+                old_attrs = gcx.getAttr(pool, bit_i);
+                gcx.setAttr(pool, bit_i, mask);
             }
-            return oldb;
+            return old_attrs;
         }
 
         if (!thread_needLock())
@@ -272,16 +281,16 @@ class GC
         uint go()
         {
             Pool* pool = gcx.findPool(p);
-            uint  oldb = 0;
+            uint  old_attrs = 0;
 
             if (pool)
             {
-                auto biti = cast(size_t)(p - pool.baseAddr) / 16;
+                auto bit_i = cast(size_t)(p - pool.baseAddr) / 16;
 
-                oldb = gcx.getBits(pool, biti);
-                gcx.clrBits(pool, biti, mask);
+                old_attrs = gcx.getAttr(pool, bit_i);
+                gcx.clrAttr(pool, bit_i, mask);
             }
-            return oldb;
+            return old_attrs;
         }
 
         if (!thread_needLock())
@@ -298,7 +307,7 @@ class GC
     /**
      *
      */
-    void *malloc(size_t size, uint bits = 0)
+    void *malloc(size_t size, uint attrs = 0)
     {
         if (!size)
         {
@@ -307,11 +316,11 @@ class GC
 
         if (!thread_needLock())
         {
-            return mallocNoSync(size, bits);
+            return mallocNoSync(size, attrs);
         }
         else synchronized (gcLock)
         {
-            return mallocNoSync(size, bits);
+            return mallocNoSync(size, attrs);
         }
     }
 
@@ -319,16 +328,21 @@ class GC
     //
     //
     //
-    private void *mallocNoSync(size_t size, uint bits = 0)
+    private void *mallocNoSync(size_t size, uint attrs = 0)
     {
         assert(size != 0);
 
+        stats.malloc_started(size, attrs);
+        scope (exit)
+            stats.malloc_finished();
+
         void *p = null;
         Bins bin;
 
         assert(gcx);
 
-        size += SENTINEL_EXTRA;
+        if (opts.options.sentinel)
+            size += SENTINEL_EXTRA;
 
         // Compute size bin
         // Cache previous binsize lookup - Dave Fladebo.
@@ -378,9 +392,10 @@ class GC
 
             // Return next item from free list
             gcx.bucket[bin] = (cast(List*)p).next;
-            if( !(bits & BlkAttr.NO_SCAN) )
-                cstring.memset(p + size, 0, binsize[bin] - size);
-            debug (MEMSTOMP) cstring.memset(p, 0xF0, size);
+            if( !(attrs & BlkAttr.NO_SCAN) )
+                memset(p + size, 0, binsize[bin] - size);
+            if (opts.options.mem_stomp)
+                memset(p, 0xF0, size);
         }
         else
         {
@@ -388,16 +403,18 @@ class GC
             if (!p)
                 onOutOfMemoryError();
         }
-        size -= SENTINEL_EXTRA;
-        p = sentinel_add(p);
-        sentinel_init(p, size);
+        if (opts.options.sentinel) {
+            size -= SENTINEL_EXTRA;
+            p = sentinel_add(p);
+            sentinel_init(p, size);
+        }
 
-        if (bits)
+        if (attrs)
         {
             Pool *pool = gcx.findPool(p);
             assert(pool);
 
-            gcx.setBits(pool, cast(size_t)(p - pool.baseAddr) / 16, bits);
+            gcx.setAttr(pool, cast(size_t)(p - pool.baseAddr) / 16, attrs);
         }
         return p;
     }
@@ -406,7 +423,7 @@ class GC
     /**
      *
      */
-    void *calloc(size_t size, uint bits = 0)
+    void *calloc(size_t size, uint attrs = 0)
     {
         if (!size)
         {
@@ -415,11 +432,11 @@ class GC
 
         if (!thread_needLock())
         {
-            return callocNoSync(size, bits);
+            return callocNoSync(size, attrs);
         }
         else synchronized (gcLock)
         {
-            return callocNoSync(size, bits);
+            return callocNoSync(size, attrs);
         }
     }
 
@@ -427,12 +444,12 @@ class GC
     //
     //
     //
-    private void *callocNoSync(size_t size, uint bits = 0)
+    private void *callocNoSync(size_t size, uint attrs = 0)
     {
         assert(size != 0);
 
-        void *p = mallocNoSync(size, bits);
-        cstring.memset(p, 0, size);
+        void *p = mallocNoSync(size, attrs);
+        memset(p, 0, size);
         return p;
     }
 
@@ -440,15 +457,15 @@ class GC
     /**
      *
      */
-    void *realloc(void *p, size_t size, uint bits = 0)
+    void *realloc(void *p, size_t size, uint attrs = 0)
     {
         if (!thread_needLock())
         {
-            return reallocNoSync(p, size, bits);
+            return reallocNoSync(p, size, attrs);
         }
         else synchronized (gcLock)
         {
-            return reallocNoSync(p, size, bits);
+            return reallocNoSync(p, size, attrs);
         }
     }
 
@@ -456,7 +473,7 @@ class GC
     //
     //
     //
-    private void *reallocNoSync(void *p, size_t size, uint bits = 0)
+    private void *reallocNoSync(void *p, size_t size, uint attrs = 0)
     {
         if (!size)
         {
@@ -468,14 +485,14 @@ class GC
         }
         else if (!p)
         {
-            p = mallocNoSync(size, bits);
+            p = mallocNoSync(size, attrs);
         }
         else
         {
             void *p2;
             size_t psize;
 
-            version (SENTINEL)
+            if (opts.options.sentinel)
             {
                 sentinel_Invariant(p);
                 psize = *sentinel_size(p);
@@ -487,20 +504,20 @@ class GC
 
                         if (pool)
                         {
-                            auto biti = cast(size_t)(p - pool.baseAddr) / 16;
+                            auto bit_i = cast(size_t)(p - pool.baseAddr) / 16;
 
-                            if (bits)
+                            if (attrs)
                             {
-                                gcx.clrBits(pool, biti, BlkAttr.ALL_BITS);
-                                gcx.setBits(pool, biti, bits);
+                                gcx.clrAttr(pool, bit_i, BlkAttr.ALL_BITS);
+                                gcx.setAttr(pool, bit_i, attrs);
                             }
                             else
                             {
-                                bits = gcx.getBits(pool, biti);
+                                attrs = gcx.getAttr(pool, bit_i);
                             }
                         }
                     }
-                    p2 = mallocNoSync(size, bits);
+                    p2 = mallocNoSync(size, attrs);
                     if (psize < size)
                         size = psize;
                     cstring.memcpy(p2, p, size);
@@ -525,8 +542,8 @@ class GC
                         // Shrink in place
                         synchronized (gcLock)
                         {
-                            debug (MEMSTOMP)
-                                cstring.memset(p + size, 0xF2, psize - size);
+                            if (opts.options.mem_stomp)
+                                memset(p + size, 0xF2, psize - size);
                             pool.freePages(pagenum + newsz, psz - newsz);
                         }
                         return p;
@@ -540,10 +557,9 @@ class GC
                             {
                                 if (i == pagenum + newsz)
                                 {
-                                    debug (MEMSTOMP)
-                                        cstring.memset(p + psize, 0xF0,
-                                                size - psize);
-                                    cstring.memset(pool.pagetable + pagenum +
+                                    if (opts.options.mem_stomp)
+                                        memset(p + psize, 0xF0, size - psize);
+                                    memset(pool.pagetable + pagenum +
                                             psz, B_PAGEPLUS, newsz - psz);
                                     return p;
                                 }
@@ -567,20 +583,20 @@ class GC
 
                         if (pool)
                         {
-                            auto biti = cast(size_t)(p - pool.baseAddr) / 16;
+                            auto bit_i = cast(size_t)(p - pool.baseAddr) / 16;
 
-                            if (bits)
+                            if (attrs)
                             {
-                                gcx.clrBits(pool, biti, BlkAttr.ALL_BITS);
-                                gcx.setBits(pool, biti, bits);
+                                gcx.clrAttr(pool, bit_i, BlkAttr.ALL_BITS);
+                                gcx.setAttr(pool, bit_i, attrs);
                             }
                             else
                             {
-                                bits = gcx.getBits(pool, biti);
+                                attrs = gcx.getAttr(pool, bit_i);
                             }
                         }
                     }
-                    p2 = mallocNoSync(size, bits);
+                    p2 = mallocNoSync(size, attrs);
                     if (psize < size)
                         size = psize;
                     cstring.memcpy(p2, p, size);
@@ -624,7 +640,7 @@ class GC
     }
     body
     {
-        version (SENTINEL)
+        if (opts.options.sentinel)
         {
             return 0;
         }
@@ -654,9 +670,9 @@ class GC
         }
         if (sz < minsz)
             return 0;
-        debug (MEMSTOMP)
-            cstring.memset(p + psize, 0xF0, (psz + sz) * PAGESIZE - psize);
-        cstring.memset(pool.pagetable + pagenum + psz, B_PAGEPLUS, sz);
+        if (opts.options.mem_stomp)
+            memset(p + psize, 0xF0, (psz + sz) * PAGESIZE - psize);
+        memset(pool.pagetable + pagenum + psz, B_PAGEPLUS, sz);
         gcx.p_cache = null;
         gcx.size_cache = 0;
         return (psz + sz) * PAGESIZE;
@@ -727,17 +743,19 @@ class GC
         Pool*  pool;
         size_t pagenum;
         Bins   bin;
-        size_t biti;
+        size_t bit_i;
 
         // Find which page it is in
         pool = gcx.findPool(p);
         if (!pool)                              // if not one of ours
             return;                             // ignore
-        sentinel_Invariant(p);
-        p = sentinel_sub(p);
+        if (opts.options.sentinel) {
+            sentinel_Invariant(p);
+            p = sentinel_sub(p);
+        }
         pagenum = cast(size_t)(p - pool.baseAddr) / PAGESIZE;
-        biti = cast(size_t)(p - pool.baseAddr) / 16;
-        gcx.clrBits(pool, biti, BlkAttr.ALL_BITS);
+        bit_i = cast(size_t)(p - pool.baseAddr) / 16;
+        gcx.clrAttr(pool, bit_i, BlkAttr.ALL_BITS);
 
         bin = cast(Bins)pool.pagetable[pagenum];
         if (bin == B_PAGE)              // if large alloc
@@ -747,7 +765,8 @@ class GC
             size_t n = pagenum;
             while (++n < pool.npages && pool.pagetable[n] == B_PAGEPLUS)
                 npages++;
-            debug (MEMSTOMP) cstring.memset(p, 0xF2, npages * PAGESIZE);
+            if (opts.options.mem_stomp)
+                memset(p, 0xF2, npages * PAGESIZE);
             pool.freePages(pagenum, npages);
         }
         else
@@ -755,7 +774,8 @@ class GC
             // Add to free list
             List *list = cast(List*)p;
 
-            debug (MEMSTOMP) cstring.memset(p, 0xF2, binsize[bin]);
+            if (opts.options.mem_stomp)
+                memset(p, 0xF2, binsize[bin]);
 
             list.next = gcx.bucket[bin];
             gcx.bucket[bin] = list;
@@ -828,7 +848,7 @@ class GC
     {
         assert (p);
 
-        version (SENTINEL)
+        if (opts.options.sentinel)
         {
             p = sentinel_sub(p);
             size_t size = gcx.findSize(p);
@@ -930,7 +950,8 @@ class GC
     {
         assert(p);
 
-        sentinel_Invariant(p);
+        if (opts.options.sentinel)
+            sentinel_Invariant(p);
         debug (PTRCHECK)
         {
             Pool*  pool;
@@ -938,7 +959,8 @@ class GC
             Bins   bin;
             size_t size;
 
-            p = sentinel_sub(p);
+            if (opts.options.sentinel)
+                p = sentinel_sub(p);
             pool = gcx.findPool(p);
             assert(pool);
             pagenum = cast(size_t)(p - pool.baseAddr) / PAGESIZE;
@@ -1000,11 +1022,13 @@ class GC
 
         if (!thread_needLock())
         {
-            gcx.addRoot(p);
+            if (roots.append(p) is null)
+                onOutOfMemoryError();
         }
         else synchronized (gcLock)
         {
-            gcx.addRoot(p);
+            if (roots.append(p) is null)
+                onOutOfMemoryError();
         }
     }
 
@@ -1019,14 +1043,16 @@ class GC
             return;
         }
 
+        bool r;
         if (!thread_needLock())
         {
-            gcx.removeRoot(p);
+            r = roots.remove(p);
         }
         else synchronized (gcLock)
         {
-            gcx.removeRoot(p);
+            r = roots.remove(p);
         }
+        assert (r);
     }
 
 
@@ -1042,11 +1068,13 @@ class GC
 
         if (!thread_needLock())
         {
-            gcx.addRange(p, p + sz);
+            if (ranges.append(Range(p, p+sz)) is null)
+                onOutOfMemoryError();
         }
         else synchronized (gcLock)
         {
-            gcx.addRange(p, p + sz);
+            if (ranges.append(Range(p, p+sz)) is null)
+                onOutOfMemoryError();
         }
     }
 
@@ -1061,14 +1089,16 @@ class GC
             return;
         }
 
+        bool r;
         if (!thread_needLock())
         {
-            gcx.removeRange(p);
+            r = ranges.remove(Range(p, null));
         }
         else synchronized (gcLock)
         {
-            gcx.removeRange(p);
+            r = ranges.remove(Range(p, null));
         }
+        assert (r);
     }
 
 
@@ -1161,11 +1191,11 @@ class GC
         size_t n;
         size_t bsize = 0;
 
-        cstring.memset(&stats, 0, GCStats.sizeof);
+        memset(&stats, 0, GCStats.sizeof);
 
-        for (n = 0; n < gcx.npools; n++)
+        for (n = 0; n < pools.length; n++)
         {
-            Pool *pool = gcx.pooltable[n];
+            Pool* pool = pools[n];
             psize += pool.npages * PAGESIZE;
             for (size_t j = 0; j < pool.npages; j++)
             {
@@ -1318,6 +1348,13 @@ struct Range
 {
     void *pbot;
     void *ptop;
+    int opCmp(in Range other)
+    {
+        if (pbot < other.pbot)
+            return -1;
+        else
+        return cast(int)(pbot > other.pbot);
+    }
 }
 
 
@@ -1325,6 +1362,13 @@ const uint binsize[B_MAX] = [ 16,32,64,128,256,512,1024,2048,4096 ];
 const uint notbinsize[B_MAX] = [ ~(16u-1),~(32u-1),~(64u-1),~(128u-1),~(256u-1),
                                 ~(512u-1),~(1024u-1),~(2048u-1),~(4096u-1) ];
 
+DynArray!(void*) roots;
+
+DynArray!(Range) ranges;
+
+DynArray!(Pool) pools;
+
+
 /* ============================ Gcx =============================== */
 
 
@@ -1334,14 +1378,6 @@ struct Gcx
     void *p_cache;
     size_t size_cache;
 
-    size_t nroots;
-    size_t rootdim;
-    void **roots;
-
-    size_t nranges;
-    size_t rangedim;
-    Range *ranges;
-
     uint noStack;       // !=0 means don't scan stack
     uint log;           // turn on logging
     uint anychanges;
@@ -1352,9 +1388,6 @@ struct Gcx
     byte *minAddr;      // min(baseAddr)
     byte *maxAddr;      // max(topAddr)
 
-    size_t npools;
-    Pool **pooltable;
-
     List *bucket[B_MAX];        // free list for each size
 
 
@@ -1368,30 +1401,6 @@ struct Gcx
     }
 
 
-    void Dtor()
-    {
-        inited = 0;
-
-        for (size_t i = 0; i < npools; i++)
-        {
-            Pool *pool = pooltable[i];
-            pool.Dtor();
-            cstdlib.free(pool);
-        }
-
-        // Even when free() 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 (pooltable)
-            cstdlib.free(pooltable);
-        if (roots)
-            cstdlib.free(roots);
-        if (ranges)
-            cstdlib.free(ranges);
-    }
-
-
     void Invariant() { }
 
 
@@ -1402,41 +1411,32 @@ struct Gcx
         //printf("Gcx.invariant(): this = %p\n", this);
             size_t i;
 
-            for (i = 0; i < npools; i++)
+            for (i = 0; i < pools.length; i++)
             {
-                Pool *pool = pooltable[i];
+                Pool* pool = pools[i];
                 pool.Invariant();
                 if (i == 0)
                 {
                     assert(minAddr == pool.baseAddr);
                 }
-                if (i + 1 < npools)
+                if (i + 1 < pools.length)
                 {
-                    assert(pool.opCmp(pooltable[i + 1]) < 0);
+                    assert(*pool < pools[i + 1]);
                 }
-                else if (i + 1 == npools)
+                else if (i + 1 == pools.length)
                 {
                     assert(maxAddr == pool.topAddr);
                 }
             }
 
-            if (roots)
-            {
-                assert(rootdim != 0);
-                assert(nroots <= rootdim);
-            }
+            roots.Invariant();
+            ranges.Invariant();
 
-            if (ranges)
+            for (i = 0; i < ranges.length; i++)
             {
-                assert(rangedim != 0);
-                assert(nranges <= rangedim);
-
-                for (i = 0; i < nranges; i++)
-                {
-                    assert(ranges[i].pbot);
-                    assert(ranges[i].ptop);
-                    assert(ranges[i].pbot <= ranges[i].ptop);
-                }
+                assert(ranges[i].pbot);
+                assert(ranges[i].ptop);
+                assert(ranges[i].pbot <= ranges[i].ptop);
             }
 
             for (i = 0; i < B_PAGE; i++)
@@ -1449,120 +1449,23 @@ struct Gcx
     }
 
 
-    /**
-     *
-     */
-    void addRoot(void *p)
-    {
-        if (nroots == rootdim)
-        {
-            size_t newdim = rootdim * 2 + 16;
-            void** newroots;
-
-            newroots = cast(void**) cstdlib.malloc(newdim * newroots[0].sizeof);
-            if (!newroots)
-                onOutOfMemoryError();
-            if (roots)
-            {
-                cstring.memcpy(newroots, roots, nroots * newroots[0].sizeof);
-                cstdlib.free(roots);
-            }
-            roots = newroots;
-            rootdim = newdim;
-        }
-        roots[nroots] = p;
-        nroots++;
-    }
-
-
-    /**
-     *
-     */
-    void removeRoot(void *p)
-    {
-        for (size_t i = nroots; i--;)
-        {
-            if (roots[i] == p)
-            {
-                nroots--;
-                cstring.memmove(roots + i, roots + i + 1,
-                        (nroots - i) * roots[0].sizeof);
-                return;
-            }
-        }
-        assert(0);
-    }
-
-
-    /**
-     *
-     */
-    void addRange(void *pbot, void *ptop)
-    {
-        if (nranges == rangedim)
-        {
-            size_t newdim = rangedim * 2 + 16;
-            Range *newranges;
-
-            newranges = cast(Range*) cstdlib.malloc(newdim * Range.sizeof);
-            if (!newranges)
-                onOutOfMemoryError();
-            if (ranges)
-            {
-                cstring.memcpy(newranges, ranges, nranges * Range.sizeof);
-                cstdlib.free(ranges);
-            }
-            ranges = newranges;
-            rangedim = newdim;
-        }
-        ranges[nranges].pbot = pbot;
-        ranges[nranges].ptop = ptop;
-        nranges++;
-    }
-
-
-    /**
-     *
-     */
-    void removeRange(void *pbot)
-    {
-        for (size_t i = nranges; i--;)
-        {
-            if (ranges[i].pbot == pbot)
-            {
-                nranges--;
-                cstring.memmove(ranges + i, ranges + i + 1,
-                        (nranges - i) * ranges[0].sizeof);
-                return;
-            }
-        }
-
-        // This is a fatal error, but ignore it.
-        // The problem is that we can get a Close() call on a thread
-        // other than the one the range was allocated on.
-        //assert(zero);
-    }
-
-
     /**
      * Find Pool that pointer is in.
      * Return null if not in a Pool.
-     * Assume pooltable[] is sorted.
+     * Assume pools is sorted.
      */
     Pool *findPool(void *p)
     {
         if (p >= minAddr && p < maxAddr)
         {
-            if (npools == 1)
+            if (pools.length == 1)
             {
-                return pooltable[0];
+                return pools[0];
             }
 
-            for (size_t i = 0; i < npools; i++)
+            for (size_t i = 0; i < pools.length; i++)
             {
-                Pool *pool;
-
-                pool = pooltable[i];
+                Pool* pool = pools[i];
                 if (p < pool.topAddr)
                 {
                     if (pool.baseAddr <= p)
@@ -1707,10 +1610,10 @@ struct Gcx
             }
 
             ////////////////////////////////////////////////////////////////////
-            // getBits
+            // getAttr
             ////////////////////////////////////////////////////////////////////
 
-            info.attr = getBits(pool, cast(size_t)(offset / 16));
+            info.attr = getAttr(pool, cast(size_t)(offset / 16));
         }
         return info;
     }
@@ -1764,7 +1667,7 @@ struct Gcx
 
     /**
      * Allocate a new pool of at least size bytes.
-     * Sort it into pooltable[].
+     * Sort it into pools.
      * Mark all memory in the pool as B_FREE.
      * Return the actual number of bytes reserved or 0 on error.
      */
@@ -1788,27 +1691,22 @@ struct Gcx
         size_t pn;
         Pool*  pool;
 
-        for (n = 0; n < npools; n++)
+        for (n = 0; n < pools.length; n++)
         {
-            pool = pooltable[n];
+            pool = pools[n];
             for (pn = 0; pn < pool.npages; pn++)
             {
                 if (cast(Bins)pool.pagetable[pn] != B_FREE)
                     break;
             }
             if (pn < pool.npages)
-            {
-                n++;
                 continue;
-            }
             pool.Dtor();
-            cstdlib.free(pool);
-            cstring.memmove(pooltable + n,
-                            pooltable + n + 1,
-                            (--npools - n) * (Pool*).sizeof);
-            minAddr = pooltable[0].baseAddr;
-            maxAddr = pooltable[npools - 1].topAddr;
+            pools.remove_at(n);
+            n--;
         }
+        minAddr = pools[0].baseAddr;
+        maxAddr = pools[pools.length - 1].topAddr;
     }
 
 
@@ -1833,9 +1731,9 @@ struct Gcx
             // This code could use some refinement when repeatedly
             // allocating very large arrays.
 
-            for (n = 0; n < npools; n++)
+            for (n = 0; n < pools.length; n++)
             {
-                pool = pooltable[n];
+                pool = pools[n];
                 pn = pool.allocPages(npages);
                 if (pn != OPFAIL)
                     goto L1;
@@ -1852,7 +1750,7 @@ struct Gcx
                 }
                 // Try collecting
                 freedpages = fullcollectshell();
-                if (freedpages >= npools * ((POOLSIZE / PAGESIZE) / 4))
+                if (freedpages >= pools.length * ((POOLSIZE / PAGESIZE) / 4))
                 {
                     state = 1;
                     continue;
@@ -1889,10 +1787,11 @@ struct Gcx
       L1:
         pool.pagetable[pn] = B_PAGE;
         if (npages > 1)
-            cstring.memset(&pool.pagetable[pn + 1], B_PAGEPLUS, npages - 1);
+            memset(&pool.pagetable[pn + 1], B_PAGEPLUS, npages - 1);
         p = pool.baseAddr + pn * PAGESIZE;
-        cstring.memset(cast(char *)p + size, 0, npages * PAGESIZE - size);
-        debug (MEMSTOMP) cstring.memset(p, 0xF1, size);
+        memset(cast(char *)p + size, 0, npages * PAGESIZE - size);
+        if (opts.options.mem_stomp)
+            memset(p, 0xF1, size);
         return p;
 
       Lnomemory:
@@ -1902,16 +1801,11 @@ struct Gcx
 
     /**
      * Allocate a new pool with at least npages in it.
-     * Sort it into pooltable[].
+     * Sort it into pools.
      * Return null if failed.
      */
     Pool *newPool(size_t npages)
     {
-        Pool*  pool;
-        Pool** newpooltable;
-        size_t newnpools;
-        size_t i;
-
         // Minimum of POOLSIZE
         if (npages < POOLSIZE/PAGESIZE)
             npages = POOLSIZE/PAGESIZE;
@@ -1924,9 +1818,9 @@ struct Gcx
         }
 
         // Allocate successively larger pools up to 8 megs
-        if (npools)
+        if (pools.length)
         {
-            size_t n = npools;
+            size_t n = pools.length;
             if (n > 8)
                 n = 8;                  // cap pool size at 8 megs
             n *= (POOLSIZE / PAGESIZE);
@@ -1934,41 +1828,21 @@ struct Gcx
                 npages = n;
         }
 
-        pool = cast(Pool *) cstdlib.calloc(1, Pool.sizeof);
-        if (pool)
+        Pool p;
+        p.initialize(npages);
+        if (!p.baseAddr)
         {
-            pool.initialize(npages);
-            if (!pool.baseAddr)
-                goto Lerr;
-
-            newnpools = npools + 1;
-            newpooltable = cast(Pool **) cstdlib.realloc(pooltable,
-                    newnpools * (Pool *).sizeof);
-            if (!newpooltable)
-                goto Lerr;
-
-            // Sort pool into newpooltable[]
-            for (i = 0; i < npools; i++)
-            {
-                if (pool.opCmp(newpooltable[i]) < 0)
-                     break;
-            }
-            cstring.memmove(newpooltable + i + 1, newpooltable + i,
-                    (npools - i) * (Pool *).sizeof);
-            newpooltable[i] = pool;
-
-            pooltable = newpooltable;
-            npools = newnpools;
+            p.Dtor();
+            return null;
+        }
 
-            minAddr = pooltable[0].baseAddr;
-            maxAddr = pooltable[npools - 1].topAddr;
+        Pool* pool = pools.insert_sorted(p);
+        if (pool)
+        {
+            minAddr = pools[0].baseAddr;
+            maxAddr = pools[pools.length - 1].topAddr;
         }
         return pool;
-
-      Lerr:
-        pool.Dtor();
-        cstdlib.free(pool);
-        return null;
     }
 
 
@@ -1985,9 +1859,9 @@ struct Gcx
         byte*  p;
         byte*  ptop;
 
-        for (n = 0; n < npools; n++)
+        for (n = 0; n < pools.length; n++)
         {
-            pool = pooltable[n];
+            pool = pools[n];
             pn = pool.allocPages(1);
             if (pn != OPFAIL)
                 goto L1;
@@ -2037,13 +1911,13 @@ struct Gcx
                 if (pool)
                 {
                     size_t offset = cast(size_t)(p - pool.baseAddr);
-                    size_t biti;
+                    size_t bit_i;
                     size_t pn = offset / PAGESIZE;
                     Bins   bin = cast(Bins)pool.pagetable[pn];
 
                     // Adjust bit to be at start of allocated memory block
                     if (bin <= B_PAGE)
-                        biti = (offset & notbinsize[bin]) >> 4;
+                        bit_i = (offset & notbinsize[bin]) >> 4;
                     else if (bin == B_PAGEPLUS)
                     {
                         do
@@ -2051,7 +1925,7 @@ struct Gcx
                             --pn;
                         }
                         while (cast(Bins)pool.pagetable[pn] == B_PAGEPLUS);
-                        biti = pn * (PAGESIZE / 16);
+                        bit_i = pn * (PAGESIZE / 16);
                     }
                     else
                     {
@@ -2062,12 +1936,12 @@ struct Gcx
                     if (bin >= B_PAGE) // Cache B_PAGE and B_PAGEPLUS lookups
                         pcache = cast(size_t)p & ~(PAGESIZE-1);
 
-                    if (!pool.mark.test(biti))
+                    if (!pool.mark.test(bit_i))
                     {
-                        pool.mark.set(biti);
-                        if (!pool.noscan.test(biti))
+                        pool.mark.set(bit_i);
+                        if (!pool.noscan.test(bit_i))
                         {
-                            pool.scan.set(biti);
+                            pool.scan.set(bit_i);
                             changes = 1;
                         }
                     }
@@ -2077,12 +1951,15 @@ struct Gcx
         anychanges |= changes;
     }
 
-
     /**
      * Return number of full pages free'd.
      */
     size_t fullcollectshell()
     {
+        stats.collection_started();
+        scope (exit)
+            stats.collection_finished();
+
         // The purpose of the 'shell' is to ensure all the registers
         // get put on the stack so they'll be scanned
         void *sp;
@@ -2176,14 +2053,15 @@ struct Gcx
         debug(COLLECT_PRINTF) printf("Gcx.fullcollect()\n");
 
         thread_suspendAll();
+        stats.world_stopped();
 
         p_cache = null;
         size_cache = 0;
 
         anychanges = 0;
-        for (n = 0; n < npools; n++)
+        for (n = 0; n < pools.length; n++)
         {
-            pool = pooltable[n];
+            pool = pools[n];
             pool.mark.zero();
             pool.scan.zero();
             pool.freebits.zero();
@@ -2200,9 +2078,9 @@ struct Gcx
             }
         }
 
-        for (n = 0; n < npools; n++)
+        for (n = 0; n < pools.length; n++)
         {
-            pool = pooltable[n];
+            pool = pools[n];
             pool.mark.copy(&pool.freebits);
         }
 
@@ -2214,14 +2092,14 @@ struct Gcx
             thread_scanAll( &mark, stackTop );
         }
 
-        // Scan roots[]
+        // Scan roots
         debug(COLLECT_PRINTF) printf("scan roots[]\n");
-        mark(roots, roots + nroots);
+        mark(roots.ptr, roots.ptr + roots.length);
 
-        // Scan ranges[]
+        // Scan ranges
         debug(COLLECT_PRINTF) printf("scan ranges[]\n");
         //log++;
-        for (n = 0; n < nranges; n++)
+        for (n = 0; n < ranges.length; n++)
         {
             debug(COLLECT_PRINTF) printf("\t%x .. %x\n", ranges[n].pbot, ranges[n].ptop);
             mark(ranges[n].pbot, ranges[n].ptop);
@@ -2232,13 +2110,13 @@ struct Gcx
         while (anychanges)
         {
             anychanges = 0;
-            for (n = 0; n < npools; n++)
+            for (n = 0; n < pools.length; n++)
             {
                 uint *bbase;
                 uint *b;
                 uint *btop;
 
-                pool = pooltable[n];
+                pool = pools[n];
 
                 bbase = pool.scan.base();
                 btop = bbase + pool.scan.nwords;
@@ -2283,7 +2161,8 @@ struct Gcx
                                     pn--;
                             }
                             u = 1;
-                            while (pn + u < pool.npages && pool.pagetable[pn + u] == B_PAGEPLUS)
+                            while (pn + u < pool.npages &&
+                                    pool.pagetable[pn + u] == B_PAGEPLUS)
                                 u++;
                             mark(o, o + u * PAGESIZE);
                         }
@@ -2293,14 +2172,15 @@ struct Gcx
         }
 
         thread_resumeAll();
+        stats.world_started();
 
         // Free up everything not marked
         debug(COLLECT_PRINTF) printf("\tfree'ing\n");
         size_t freedpages = 0;
         size_t freed = 0;
-        for (n = 0; n < npools; n++)
+        for (n = 0; n < pools.length; n++)
         {
-            pool = pooltable[n];
+            pool = pools[n];
             uint*  bbase = pool.mark.base();
             size_t pn;
             for (pn = 0; pn < pool.npages; pn++, bbase += PAGESIZE / (32 * 16))
@@ -2312,44 +2192,56 @@ struct Gcx
                     auto size = binsize[bin];
                     byte* p = pool.baseAddr + pn * PAGESIZE;
                     byte* ptop = p + PAGESIZE;
-                    size_t biti = pn * (PAGESIZE/16);
-                    size_t bitstride = size / 16;
+                    size_t bit_i = pn * (PAGESIZE/16);
+                    size_t bit_stride = size / 16;
 
     version(none) // BUG: doesn't work because freebits() must also be cleared
     {
                     // If free'd entire page
-                    if (bbase[0] == 0 && bbase[1] == 0 && bbase[2] == 0 && bbase[3] == 0 &&
-                        bbase[4] == 0 && bbase[5] == 0 && bbase[6] == 0 && bbase[7] == 0)
+                    if (bbase[0] == 0 && bbase[1] == 0 && bbase[2] == 0 &&
+                            bbase[3] == 0 && bbase[4] == 0 && bbase[5] == 0 &&
+                            bbase[6] == 0 && bbase[7] == 0)
                     {
-                        for (; p < ptop; p += size, biti += bitstride)
+                        for (; p < ptop; p += size, bit_i += bit_stride)
                         {
-                            if (pool.finals.nbits && pool.finals.testClear(biti))
-                                rt_finalize(cast(List *)sentinel_add(p), false/*noStack > 0*/);
-                            gcx.clrBits(pool, biti, BlkAttr.ALL_BITS);
+                            if (pool.finals.nbits && pool.finals.testClear(bit_i)) {
+                                if (opts.options.sentinel)
+                                    rt_finalize(cast(List *)sentinel_add(p), false/*noStack > 0*/);
+                                else
+                                    rt_finalize(cast(List *)p, false/*noStack > 0*/);
+                            }
+                            gcx.clrAttr(pool, bit_i, BlkAttr.ALL_BITS);
 
                             List *list = cast(List *)p;
 
-                            debug (MEMSTOMP) cstring.memset(p, 0xF3, size);
+                            if (opts.options.mem_stomp)
+                                memset(p, 0xF3, size);
                         }
                         pool.pagetable[pn] = B_FREE;
                         freed += PAGESIZE;
                         continue;
                     }
     }
-                    for (; p < ptop; p += size, biti += bitstride)
+                    for (; p < ptop; p += size, bit_i += bit_stride)
                     {
-                        if (!pool.mark.test(biti))
+                        if (!pool.mark.test(bit_i))
                         {
-                            sentinel_Invariant(sentinel_add(p));
-
-                            pool.freebits.set(biti);
-                            if (pool.finals.nbits && pool.finals.testClear(biti))
-                                rt_finalize(cast(List *)sentinel_add(p), false/*noStack > 0*/);
-                            clrBits(pool, biti, BlkAttr.ALL_BITS);
+                            if (opts.options.sentinel)
+                                sentinel_Invariant(sentinel_add(p));
+
+                            pool.freebits.set(bit_i);
+                            if (pool.finals.nbits && pool.finals.testClear(bit_i)) {
+                                if (opts.options.sentinel)
+                                    rt_finalize(cast(List *)sentinel_add(p), false/*noStack > 0*/);
+                                else
+                                    rt_finalize(cast(List *)p, false/*noStack > 0*/);
+                            }
+                            clrAttr(pool, bit_i, BlkAttr.ALL_BITS);
 
                             List *list = cast(List *)p;
 
-                            debug (MEMSTOMP) cstring.memset(p, 0xF3, size);
+                            if (opts.options.mem_stomp)
+                                memset(p, 0xF3, size);
 
                             freed += size;
                         }
@@ -2357,29 +2249,35 @@ struct Gcx
                 }
                 else if (bin == B_PAGE)
                 {
-                    size_t biti = pn * (PAGESIZE / 16);
-                    if (!pool.mark.test(biti))
+                    size_t bit_i = pn * (PAGESIZE / 16);
+                    if (!pool.mark.test(bit_i))
                     {
                         byte *p = pool.baseAddr + pn * PAGESIZE;
-                        sentinel_Invariant(sentinel_add(p));
-                        if (pool.finals.nbits && pool.finals.testClear(biti))
-                            rt_finalize(sentinel_add(p), false/*noStack > 0*/);
-                        clrBits(pool, biti, BlkAttr.ALL_BITS);
+                        if (opts.options.sentinel)
+                            sentinel_Invariant(sentinel_add(p));
+                        if (pool.finals.nbits && pool.finals.testClear(bit_i)) {
+                            if (opts.options.sentinel)
+                                rt_finalize(sentinel_add(p), false/*noStack > 0*/);
+                            else
+                                rt_finalize(p, false/*noStack > 0*/);
+                        }
+                        clrAttr(pool, bit_i, BlkAttr.ALL_BITS);
 
                         debug(COLLECT_PRINTF) printf("\tcollecting big %x\n", p);
                         pool.pagetable[pn] = B_FREE;
                         freedpages++;
-                        debug (MEMSTOMP) cstring.memset(p, 0xF3, PAGESIZE);
+                        if (opts.options.mem_stomp)
+                            memset(p, 0xF3, PAGESIZE);
                         while (pn + 1 < pool.npages && pool.pagetable[pn + 1] == B_PAGEPLUS)
                         {
                             pn++;
                             pool.pagetable[pn] = B_FREE;
                             freedpages++;
 
-                            debug (MEMSTOMP)
+                            if (opts.options.mem_stomp)
                             {
                                 p += PAGESIZE;
-                                cstring.memset(p, 0xF3, PAGESIZE);
+                                memset(p, 0xF3, PAGESIZE);
                             }
                         }
                     }
@@ -2393,27 +2291,27 @@ struct Gcx
         // Free complete pages, rebuild free list
         debug(COLLECT_PRINTF) printf("\tfree complete pages\n");
         size_t recoveredpages = 0;
-        for (n = 0; n < npools; n++)
+        for (n = 0; n < pools.length; n++)
         {
-            pool = pooltable[n];
+            pool = pools[n];
             for (size_t pn = 0; pn < pool.npages; pn++)
             {
                 Bins   bin = cast(Bins)pool.pagetable[pn];
-                size_t biti;
+                size_t bit_i;
                 size_t u;
 
                 if (bin < B_PAGE)
                 {
                     size_t size = binsize[bin];
-                    size_t bitstride = size / 16;
-                    size_t bitbase = pn * (PAGESIZE / 16);
-                    size_t bittop = bitbase + (PAGESIZE / 16);
+                    size_t bit_stride = size / 16;
+                    size_t bit_base = pn * (PAGESIZE / 16);
+                    size_t bit_top = bit_base + (PAGESIZE / 16);
                     byte*  p;
 
-                    biti = bitbase;
-                    for (biti = bitbase; biti < bittop; biti += bitstride)
+                    bit_i = bit_base;
+                    for (; bit_i < bit_top; bit_i += bit_stride)
                     {
-                        if (!pool.freebits.test(biti))
+                        if (!pool.freebits.test(bit_i))
                             goto Lnotfree;
                     }
                     pool.pagetable[pn] = B_FREE;
@@ -2424,11 +2322,12 @@ struct Gcx
                     p = pool.baseAddr + pn * PAGESIZE;
                     for (u = 0; u < PAGESIZE; u += size)
                     {
-                        biti = bitbase + u / 16;
-                        if (pool.freebits.test(biti))
+                        bit_i = bit_base + u / 16;
+                        if (pool.freebits.test(bit_i))
                         {
                             List *list = cast(List *)(p + u);
-                            if (list.next != bucket[bin])       // avoid unnecessary writes
+                            // avoid unnecessary writes
+                            if (list.next != bucket[bin])
                                 list.next = bucket[bin];
                             bucket[bin] = list;
                         }
@@ -2438,7 +2337,7 @@ struct Gcx
         }
 
         debug(COLLECT_PRINTF) printf("recovered pages = %d\n", recoveredpages);
-        debug(COLLECT_PRINTF) printf("\tfree'd %u bytes, %u pages from %u pools\n", freed, freedpages, npools);
+        debug(COLLECT_PRINTF) printf("\tfree'd %u bytes, %u pages from %u pools\n", freed, freedpages, pools.length);
 
         return freedpages + recoveredpages;
     }
@@ -2447,31 +2346,31 @@ struct Gcx
     /**
      *
      */
-    uint getBits(Pool* pool, size_t biti)
+    uint getAttr(Pool* pool, size_t bit_i)
     in
     {
         assert( pool );
     }
     body
     {
-        uint bits;
+        uint attrs;
 
         if (pool.finals.nbits &&
-            pool.finals.test(biti))
-            bits |= BlkAttr.FINALIZE;
-        if (pool.noscan.test(biti))
-            bits |= BlkAttr.NO_SCAN;
+            pool.finals.test(bit_i))
+            attrs |= BlkAttr.FINALIZE;
+        if (pool.noscan.test(bit_i))
+            attrs |= BlkAttr.NO_SCAN;
 //        if (pool.nomove.nbits &&
-//            pool.nomove.test(biti))
-//            bits |= BlkAttr.NO_MOVE;
-        return bits;
+//            pool.nomove.test(bit_i))
+//            attrs |= BlkAttr.NO_MOVE;
+        return attrs;
     }
 
 
     /**
      *
      */
-    void setBits(Pool* pool, size_t biti, uint mask)
+    void setAttr(Pool* pool, size_t bit_i, uint mask)
     in
     {
         assert( pool );
@@ -2482,17 +2381,17 @@ struct Gcx
         {
             if (!pool.finals.nbits)
                 pool.finals.alloc(pool.mark.nbits);
-            pool.finals.set(biti);
+            pool.finals.set(bit_i);
         }
         if (mask & BlkAttr.NO_SCAN)
         {
-            pool.noscan.set(biti);
+            pool.noscan.set(bit_i);
         }
 //        if (mask & BlkAttr.NO_MOVE)
 //        {
 //            if (!pool.nomove.nbits)
 //                pool.nomove.alloc(pool.mark.nbits);
-//            pool.nomove.set(biti);
+//            pool.nomove.set(bit_i);
 //        }
     }
 
@@ -2500,7 +2399,7 @@ struct Gcx
     /**
      *
      */
-    void clrBits(Pool* pool, size_t biti, uint mask)
+    void clrAttr(Pool* pool, size_t bit_i, uint mask)
     in
     {
         assert( pool );
@@ -2508,11 +2407,11 @@ struct Gcx
     body
     {
         if (mask & BlkAttr.FINALIZE && pool.finals.nbits)
-            pool.finals.clear(biti);
+            pool.finals.clear(bit_i);
         if (mask & BlkAttr.NO_SCAN)
-            pool.noscan.clear(biti);
+            pool.noscan.clear(bit_i);
 //        if (mask & BlkAttr.NO_MOVE && pool.nomove.nbits)
-//            pool.nomove.clear(biti);
+//            pool.nomove.clear(bit_i);
     }
 
 }
@@ -2560,7 +2459,7 @@ struct Pool
         pagetable = cast(ubyte*) cstdlib.malloc(npages);
         if (!pagetable)
             onOutOfMemoryError();
-        cstring.memset(pagetable, B_FREE, npages);
+        memset(pagetable, B_FREE, npages);
 
         this.npages = npages;
     }
@@ -2649,19 +2548,19 @@ struct Pool
      */
     void freePages(size_t pagenum, size_t npages)
     {
-        cstring.memset(&pagetable[pagenum], B_FREE, npages);
+        memset(&pagetable[pagenum], B_FREE, npages);
     }
 
 
     /**
-     * Used for sorting pooltable[]
+     * Used for sorting pools
      */
-    int opCmp(Pool *p2)
+    int opCmp(in Pool other)
     {
-        if (baseAddr < p2.baseAddr)
+        if (baseAddr < other.baseAddr)
             return -1;
         else
-        return cast(int)(baseAddr > p2.baseAddr);
+        return cast(int)(baseAddr > other.baseAddr);
     }
 }
 
@@ -2669,69 +2568,40 @@ struct Pool
 /* ============================ SENTINEL =============================== */
 
 
-version (SENTINEL)
-{
-    const size_t SENTINEL_PRE = cast(size_t) 0xF4F4F4F4F4F4F4F4UL; // 32 or 64 bits
-    const ubyte SENTINEL_POST = 0xF5;           // 8 bits
-    const uint SENTINEL_EXTRA = 2 * size_t.sizeof + 1;
-
+const size_t SENTINEL_PRE = cast(size_t) 0xF4F4F4F4F4F4F4F4UL; // 32 or 64 bits
+const ubyte SENTINEL_POST = 0xF5;           // 8 bits
+const uint SENTINEL_EXTRA = 2 * size_t.sizeof + 1;
 
-    size_t* sentinel_size(void *p)  { return &(cast(size_t *)p)[-2]; }
-    size_t* sentinel_pre(void *p)   { return &(cast(size_t *)p)[-1]; }
-    ubyte* sentinel_post(void *p) { return &(cast(ubyte *)p)[*sentinel_size(p)]; }
 
+size_t* sentinel_size(void *p)  { return &(cast(size_t *)p)[-2]; }
+size_t* sentinel_pre(void *p)   { return &(cast(size_t *)p)[-1]; }
+ubyte* sentinel_post(void *p) { return &(cast(ubyte *)p)[*sentinel_size(p)]; }
 
-    void sentinel_init(void *p, size_t size)
-    {
-        *sentinel_size(p) = size;
-        *sentinel_pre(p) = SENTINEL_PRE;
-        *sentinel_post(p) = SENTINEL_POST;
-    }
 
-
-    void sentinel_Invariant(void *p)
-    {
-        assert(*sentinel_pre(p) == SENTINEL_PRE);
-        assert(*sentinel_post(p) == SENTINEL_POST);
-    }
-
-
-    void *sentinel_add(void *p)
-    {
-        return p + 2 * size_t.sizeof;
-    }
-
-
-    void *sentinel_sub(void *p)
-    {
-        return p - 2 * size_t.sizeof;
-    }
-}
-else
+void sentinel_init(void *p, size_t size)
 {
-    const uint SENTINEL_EXTRA = 0;
-
-
-    void sentinel_init(void *p, size_t size)
-    {
-    }
+    *sentinel_size(p) = size;
+    *sentinel_pre(p) = SENTINEL_PRE;
+    *sentinel_post(p) = SENTINEL_POST;
+}
 
 
-    void sentinel_Invariant(void *p)
-    {
-    }
+void sentinel_Invariant(void *p)
+{
+    assert(*sentinel_pre(p) == SENTINEL_PRE);
+    assert(*sentinel_post(p) == SENTINEL_POST);
+}
 
 
-    void *sentinel_add(void *p)
-    {
-        return p;
-    }
+void *sentinel_add(void *p)
+{
+    return p + 2 * size_t.sizeof;
+}
 
 
-    void *sentinel_sub(void *p)
-    {
-        return p;
-    }
+void *sentinel_sub(void *p)
+{
+    return p - 2 * size_t.sizeof;
 }