stats: Add more type information to malloc logging

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

diff --git a/rt/gc/cdgc/gc.d b/rt/gc/cdgc/gc.d
index 3292622d8a08c944d9292b8adbc05a3ef6915748..f5e088c54cd04351d0de17f8b0c26d9f0bab453f 100644 (file)
--- a/rt/gc/cdgc/gc.d
+++ b/rt/gc/cdgc/gc.d
@@ -31,8 +31,6 @@ module rt.gc.cdgc.gc;
 /************** Debugging ***************************/
 
 //debug = COLLECT_PRINTF;       // turn on printf's
 /************** 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
 
 //debug = PTRCHECK;             // more pointer checking
 //debug = PTRCHECK2;            // thorough but slow pointer checking
 


@@ -45,13 +43,30 @@ version = STACKGROWSDOWN;       // growing the stack means subtracting from the
 /***************************************************/
 
 import rt.gc.cdgc.bits: GCBits;
 /***************************************************/
 
 import rt.gc.cdgc.bits: GCBits;

-import rt.gc.cdgc.stats: GCStats;
-import alloc = rt.gc.cdgc.alloc;
+import rt.gc.cdgc.stats: GCStats, Stats;

 import rt.gc.cdgc.dynarray: DynArray;
 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;
 
 
 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)
 {
 
 version (GNU)
 {


@@ -62,7 +77,6 @@ version (GNU)
     static import gcc.builtins; // for __builtin_unwind_int
 }
 
     static import gcc.builtins; // for __builtin_unwind_int
 }
 

-

 struct BlkInfo
 {
     void*  base;
 struct BlkInfo
 {
     void*  base;


@@ -70,15 +84,16 @@ struct BlkInfo
     uint   attr;
 }
 
     uint   attr;
 }
 

+package enum BlkAttr : uint
+{
+    FINALIZE = 0b0000_0001,
+    NO_SCAN  = 0b0000_0010,
+    NO_MOVE  = 0b0000_0100,
+    ALL_BITS = 0b1111_1111
+}
+

 private
 {
 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();
 
     extern (C) void* rt_stackBottom();
     extern (C) void* rt_stackTop();


@@ -121,6 +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.
 
 const uint GCVERSION = 1;       // increment every time we change interface
                                 // to GC.
 

+Stats stats;
+

 class GC
 {
     // For passing to debug code
 class GC
 {
     // For passing to debug code


@@ -135,12 +152,14 @@ class GC
 
     void initialize()
     {
 
     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());
         gcLock = GCLock.classinfo;
         gcx = cast(Gcx*) cstdlib.calloc(1, Gcx.sizeof);
         if (!gcx)
             onOutOfMemoryError();
         gcx.initialize();
         setStackBottom(rt_stackBottom());

+        stats = Stats(this);

     }
 
 
     }
 
 


@@ -191,15 +210,15 @@ class GC
         uint go()
         {
             Pool* pool = gcx.findPool(p);
         uint go()
         {
             Pool* pool = gcx.findPool(p);

-            uint  oldb = 0;
+            uint  old_attrs = 0;

 
             if (pool)
             {
 
             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())
         }
 
         if (!thread_needLock())


@@ -226,16 +245,16 @@ class GC
         uint go()
         {
             Pool* pool = gcx.findPool(p);
         uint go()
         {
             Pool* pool = gcx.findPool(p);

-            uint  oldb = 0;
+            uint  old_attrs = 0;

 
             if (pool)
             {
 
             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())
         }
 
         if (!thread_needLock())


@@ -262,16 +281,16 @@ class GC
         uint go()
         {
             Pool* pool = gcx.findPool(p);
         uint go()
         {
             Pool* pool = gcx.findPool(p);

-            uint  oldb = 0;
+            uint  old_attrs = 0;

 
             if (pool)
             {
 
             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())
         }
 
         if (!thread_needLock())


@@ -288,7 +307,7 @@ class GC
     /**
      *
      */
     /**
      *
      */

-    void *malloc(size_t size, uint bits = 0)
+    void *malloc(size_t size, uint attrs, PointerMap ptrmap)

     {
         if (!size)
         {
     {
         if (!size)
         {


@@ -297,11 +316,11 @@ class GC
 
         if (!thread_needLock())
         {
 
         if (!thread_needLock())
         {

-            return mallocNoSync(size, bits);
+            return mallocNoSync(size, attrs, ptrmap.bits.ptr);

         }
         else synchronized (gcLock)
         {
         }
         else synchronized (gcLock)
         {

-            return mallocNoSync(size, bits);
+            return mallocNoSync(size, attrs, ptrmap.bits.ptr);

         }
     }
 
         }
     }
 


@@ -309,16 +328,27 @@ class GC
     //
     //
     //
     //
     //
     //

-    private void *mallocNoSync(size_t size, uint bits = 0)
+    private void *mallocNoSync(size_t size, uint attrs, size_t* pm_bitmask)

     {
         assert(size != 0);
 
     {
         assert(size != 0);
 

+        stats.malloc_started(size, attrs, pm_bitmask);
+        scope (exit)
+            stats.malloc_finished(p);
+

         void *p = null;
         Bins bin;
 
         assert(gcx);
 
         void *p = null;
         Bins bin;
 
         assert(gcx);
 

-        size += SENTINEL_EXTRA;
+        if (opts.options.sentinel)
+            size += SENTINEL_EXTRA;
+
+        bool has_pm = !(attrs & BlkAttr.NO_SCAN);
+        size_t pm_bitmask_size;
+        if (has_pm)
+            pm_bitmask_size = (size_t*).sizeof;
+        size += pm_bitmask_size;

 
         // Compute size bin
         // Cache previous binsize lookup - Dave Fladebo.
 
         // Compute size bin
         // Cache previous binsize lookup - Dave Fladebo.


@@ -333,6 +363,7 @@ class GC
             lastbin = bin;
         }
 
             lastbin = bin;
         }
 

+        size_t capacity; // to figure out where to store the bitmask

         if (bin < B_PAGE)
         {
             p = gcx.bucket[bin];
         if (bin < B_PAGE)
         {
             p = gcx.bucket[bin];


@@ -365,29 +396,45 @@ class GC
                 }
                 p = gcx.bucket[bin];
             }
                 }
                 p = gcx.bucket[bin];
             }

+            capacity = binsize[bin];

 
             // Return next item from free list
             gcx.bucket[bin] = (cast(List*)p).next;
 
             // 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, capacity - size);
+            if (opts.options.mem_stomp)
+                memset(p, 0xF0, size);

         }
         else
         {
             p = gcx.bigAlloc(size);
             if (!p)
                 onOutOfMemoryError();
         }
         else
         {
             p = gcx.bigAlloc(size);
             if (!p)
                 onOutOfMemoryError();

+            // Round the size up to the number of pages needed to store it
+            size_t npages = (size + PAGESIZE - 1) / PAGESIZE;
+            capacity = npages * PAGESIZE;
+        }
+
+        // Store the bit mask AFTER SENTINEL_POST
+        // TODO: store it BEFORE, so the bitmask is protected too
+        if (has_pm) {
+            auto end_of_blk = cast(size_t**)(p + capacity - pm_bitmask_size);
+            *end_of_blk = pm_bitmask;
+            size -= pm_bitmask_size;
+        }
+
+        if (opts.options.sentinel) {
+            size -= SENTINEL_EXTRA;
+            p = sentinel_add(p);
+            sentinel_init(p, size);

         }
         }

-        size -= SENTINEL_EXTRA;
-        p = sentinel_add(p);
-        sentinel_init(p, size);

 
 

-        if (bits)
+        if (attrs)

         {
             Pool *pool = gcx.findPool(p);
             assert(pool);
 
         {
             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;
     }
         }
         return p;
     }


@@ -396,7 +443,7 @@ class GC
     /**
      *
      */
     /**
      *
      */

-    void *calloc(size_t size, uint bits = 0)
+    void *calloc(size_t size, uint attrs, PointerMap ptrmap)

     {
         if (!size)
         {
     {
         if (!size)
         {


@@ -405,11 +452,11 @@ class GC
 
         if (!thread_needLock())
         {
 
         if (!thread_needLock())
         {

-            return callocNoSync(size, bits);
+            return callocNoSync(size, attrs, ptrmap.bits.ptr);

         }
         else synchronized (gcLock)
         {
         }
         else synchronized (gcLock)
         {

-            return callocNoSync(size, bits);
+            return callocNoSync(size, attrs, ptrmap.bits.ptr);

         }
     }
 
         }
     }
 


@@ -417,12 +464,12 @@ class GC
     //
     //
     //
     //
     //
     //

-    private void *callocNoSync(size_t size, uint bits = 0)
+    private void *callocNoSync(size_t size, uint attrs, size_t* pm_bitmask)

     {
         assert(size != 0);
 
     {
         assert(size != 0);
 

-        void *p = mallocNoSync(size, bits);
-        cstring.memset(p, 0, size);
+        void *p = mallocNoSync(size, attrs, pm_bitmask);
+        memset(p, 0, size);

         return p;
     }
 
         return p;
     }
 


@@ -430,15 +477,15 @@ class GC
     /**
      *
      */
     /**
      *
      */

-    void *realloc(void *p, size_t size, uint bits = 0)
+    void *realloc(void *p, size_t size, uint attrs, PointerMap ptrmap)

     {
         if (!thread_needLock())
         {
     {
         if (!thread_needLock())
         {

-            return reallocNoSync(p, size, bits);
+            return reallocNoSync(p, size, attrs, ptrmap.bits.ptr);

         }
         else synchronized (gcLock)
         {
         }
         else synchronized (gcLock)
         {

-            return reallocNoSync(p, size, bits);
+            return reallocNoSync(p, size, attrs, ptrmap.bits.ptr);

         }
     }
 
         }
     }
 


@@ -446,7 +493,8 @@ class GC
     //
     //
     //
     //
     //
     //

-    private void *reallocNoSync(void *p, size_t size, uint bits = 0)
+    private void *reallocNoSync(void *p, size_t size, uint attrs,
+            size_t* pm_bitmask)

     {
         if (!size)
         {
     {
         if (!size)
         {


@@ -458,56 +506,60 @@ class GC
         }
         else if (!p)
         {
         }
         else if (!p)
         {

-            p = mallocNoSync(size, bits);
+            p = mallocNoSync(size, attrs, pm_bitmask);

         }
         else
         {
         }
         else
         {

-            void *p2;
-            size_t psize;
+            Pool* pool = gcx.findPool(p);
+            if (pool is null)
+                return null;

 
 

-            version (SENTINEL)
+            // Set or retrieve attributes as appropriate
+            auto bit_i = cast(size_t)(p - pool.baseAddr) / 16;
+            if (attrs) {
+                gcx.clrAttr(pool, bit_i, BlkAttr.ALL_BITS);
+                gcx.setAttr(pool, bit_i, attrs);
+            }
+            else
+                attrs = gcx.getAttr(pool, bit_i);
+
+            void* blk_base_addr = gcx.findBase(p);
+            size_t blk_size = gcx.findSize(p);
+            bool has_pm = !(attrs & BlkAttr.NO_SCAN);
+            size_t pm_bitmask_size = 0;
+            if (has_pm) {
+                pm_bitmask_size = (size_t*).sizeof;
+                // Retrieve pointer map bit mask if appropriate
+                if (pm_bitmask is null) {
+                    auto end_of_blk = cast(size_t**)(blk_base_addr +
+                            blk_size - pm_bitmask_size);
+                    pm_bitmask = *end_of_blk;
+                }
+            }
+
+            if (opts.options.sentinel)

             {
                 sentinel_Invariant(p);
             {
                 sentinel_Invariant(p);

-                psize = *sentinel_size(p);
-                if (psize != size)
+                size_t sentinel_stored_size = *sentinel_size(p);
+                if (sentinel_stored_size != size)

                 {
                 {

-                    if (psize)
-                    {
-                        Pool *pool = gcx.findPool(p);
-
-                        if (pool)
-                        {
-                            auto biti = cast(size_t)(p - pool.baseAddr) / 16;
-
-                            if (bits)
-                            {
-                                gcx.clrBits(pool, biti, BlkAttr.ALL_BITS);
-                                gcx.setBits(pool, biti, bits);
-                            }
-                            else
-                            {
-                                bits = gcx.getBits(pool, biti);
-                            }
-                        }
-                    }
-                    p2 = mallocNoSync(size, bits);
-                    if (psize < size)
-                        size = psize;
+                    void* p2 = mallocNoSync(size, attrs, pm_bitmask);
+                    if (sentinel_stored_size < size)
+                        size = sentinel_stored_size;

                     cstring.memcpy(p2, p, size);
                     p = p2;
                 }
             }
             else
             {
                     cstring.memcpy(p2, p, size);
                     p = p2;
                 }
             }
             else
             {

-                psize = gcx.findSize(p);        // find allocated size
-                if (psize >= PAGESIZE && size >= PAGESIZE)
+                size += pm_bitmask_size;
+                if (blk_size >= PAGESIZE && size >= PAGESIZE)

                 {
                 {

-                    auto psz = psize / PAGESIZE;
+                    auto psz = blk_size / PAGESIZE;

                     auto newsz = (size + PAGESIZE - 1) / PAGESIZE;
                     if (newsz == psz)
                         return p;
 
                     auto newsz = (size + PAGESIZE - 1) / PAGESIZE;
                     if (newsz == psz)
                         return p;
 

-                    auto pool = gcx.findPool(p);

                     auto pagenum = (p - pool.baseAddr) / PAGESIZE;
 
                     if (newsz < psz)
                     auto pagenum = (p - pool.baseAddr) / PAGESIZE;
 
                     if (newsz < psz)


@@ -515,10 +567,17 @@ class GC
                         // Shrink in place
                         synchronized (gcLock)
                         {
                         // Shrink in place
                         synchronized (gcLock)
                         {

-                            debug (MEMSTOMP)
-                                cstring.memset(p + size, 0xF2, psize - size);
+                            if (opts.options.mem_stomp)
+                                memset(p + size - pm_bitmask_size, 0xF2,
+                                        blk_size - size - pm_bitmask_size);

                             pool.freePages(pagenum + newsz, psz - newsz);
                         }
                             pool.freePages(pagenum + newsz, psz - newsz);
                         }

+                        if (has_pm) {
+                            auto end_of_blk = cast(size_t**)(
+                                    blk_base_addr + (PAGESIZE * newsz) -
+                                    pm_bitmask_size);
+                            *end_of_blk = pm_bitmask;
+                        }

                         return p;
                     }
                     else if (pagenum + newsz <= pool.npages)
                         return p;
                     }
                     else if (pagenum + newsz <= pool.npages)


@@ -530,11 +589,19 @@ class GC
                             {
                                 if (i == pagenum + newsz)
                                 {
                             {
                                 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 + blk_size - pm_bitmask_size,
+                                                0xF0, size - blk_size
+                                                - pm_bitmask_size);
+                                    memset(pool.pagetable + pagenum +

                                             psz, B_PAGEPLUS, newsz - psz);
                                             psz, B_PAGEPLUS, newsz - psz);

+                                    if (has_pm) {
+                                        auto end_of_blk = cast(size_t**)(
+                                                blk_base_addr +
+                                                (PAGESIZE * newsz) -
+                                                pm_bitmask_size);
+                                        *end_of_blk = pm_bitmask;
+                                    }

                                     return p;
                                 }
                                 if (i == pool.npages)
                                     return p;
                                 }
                                 if (i == pool.npages)


@@ -548,31 +615,14 @@ class GC
                         }
                     }
                 }
                         }
                     }
                 }

-                if (psize < size ||             // if new size is bigger
-                    psize > size * 2)           // or less than half
+                // if new size is bigger or less than half
+                if (blk_size < size || blk_size > size * 2)

                 {
                 {

-                    if (psize)
-                    {
-                        Pool *pool = gcx.findPool(p);
-
-                        if (pool)
-                        {
-                            auto biti = cast(size_t)(p - pool.baseAddr) / 16;
-
-                            if (bits)
-                            {
-                                gcx.clrBits(pool, biti, BlkAttr.ALL_BITS);
-                                gcx.setBits(pool, biti, bits);
-                            }
-                            else
-                            {
-                                bits = gcx.getBits(pool, biti);
-                            }
-                        }
-                    }
-                    p2 = mallocNoSync(size, bits);
-                    if (psize < size)
-                        size = psize;
+                    size -= pm_bitmask_size;
+                    blk_size -= pm_bitmask_size;
+                    void* p2 = mallocNoSync(size, attrs, pm_bitmask);
+                    if (blk_size < size)
+                        size = blk_size;

                     cstring.memcpy(p2, p, size);
                     p = p2;
                 }
                     cstring.memcpy(p2, p, size);
                     p = p2;
                 }


@@ -614,19 +664,40 @@ class GC
     }
     body
     {
     }
     body
     {

-        version (SENTINEL)
-        {
+        if (opts.options.sentinel)
+            return 0;
+
+        Pool* pool = gcx.findPool(p);
+        if (pool is null)

             return 0;
             return 0;

+
+        // Retrieve attributes
+        auto bit_i = cast(size_t)(p - pool.baseAddr) / 16;
+        uint attrs = gcx.getAttr(pool, bit_i);
+
+        void* blk_base_addr = gcx.findBase(p);
+        size_t blk_size = gcx.findSize(p);
+        bool has_pm = !(attrs & BlkAttr.NO_SCAN);
+        size_t* pm_bitmask = null;
+        size_t pm_bitmask_size = 0;
+        if (has_pm) {
+            pm_bitmask_size = (size_t*).sizeof;
+            // Retrieve pointer map bit mask
+            auto end_of_blk = cast(size_t**)(blk_base_addr +
+                    blk_size - pm_bitmask_size);
+            pm_bitmask = *end_of_blk;

         }
         }

-        auto psize = gcx.findSize(p);   // find allocated size
-        if (psize < PAGESIZE)
-            return 0;                   // cannot extend buckets

 
 

-        auto psz = psize / PAGESIZE;
+        if (blk_size < PAGESIZE)
+            return 0; // cannot extend buckets
+
+        minsize += pm_bitmask_size;
+        maxsize += pm_bitmask_size;
+
+        auto psz = blk_size / PAGESIZE;

         auto minsz = (minsize + PAGESIZE - 1) / PAGESIZE;
         auto maxsz = (maxsize + PAGESIZE - 1) / PAGESIZE;
 
         auto minsz = (minsize + PAGESIZE - 1) / PAGESIZE;
         auto maxsz = (maxsize + PAGESIZE - 1) / PAGESIZE;
 

-        auto pool = gcx.findPool(p);

         auto pagenum = (p - pool.baseAddr) / PAGESIZE;
 
         size_t sz;
         auto pagenum = (p - pool.baseAddr) / PAGESIZE;
 
         size_t sz;


@@ -644,12 +715,22 @@ class GC
         }
         if (sz < minsz)
             return 0;
         }
         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);
+
+        size_t new_size = (psz + sz) * PAGESIZE;
+
+        if (opts.options.mem_stomp)
+            memset(p + blk_size - pm_bitmask_size, 0xF0,
+                    new_size - blk_size - pm_bitmask_size);
+        memset(pool.pagetable + pagenum + psz, B_PAGEPLUS, sz);

         gcx.p_cache = null;
         gcx.size_cache = 0;
         gcx.p_cache = null;
         gcx.size_cache = 0;

-        return (psz + sz) * PAGESIZE;
+
+        if (has_pm) {
+            new_size -= pm_bitmask_size;
+            auto end_of_blk = cast(size_t**)(blk_base_addr + new_size);
+            *end_of_blk = pm_bitmask;
+        }
+        return new_size;

     }
 
 
     }
 
 


@@ -717,17 +798,19 @@ class GC
         Pool*  pool;
         size_t pagenum;
         Bins   bin;
         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
 
         // 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;
         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
 
         bin = cast(Bins)pool.pagetable[pagenum];
         if (bin == B_PAGE)              // if large alloc


@@ -737,7 +820,8 @@ class GC
             size_t n = pagenum;
             while (++n < pool.npages && pool.pagetable[n] == B_PAGEPLUS)
                 npages++;
             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
             pool.freePages(pagenum, npages);
         }
         else


@@ -745,7 +829,8 @@ class GC
             // Add to free list
             List *list = cast(List*)p;
 
             // 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;
 
             list.next = gcx.bucket[bin];
             gcx.bucket[bin] = list;


@@ -818,39 +903,46 @@ class GC
     {
         assert (p);
 
     {
         assert (p);
 

-        version (SENTINEL)
-        {
+        if (opts.options.sentinel)

             p = sentinel_sub(p);
             p = sentinel_sub(p);

-            size_t size = gcx.findSize(p);

 
 

+        Pool* pool = gcx.findPool(p);
+        if (pool is null)
+            return 0;
+
+        auto biti = cast(size_t)(p - pool.baseAddr) / 16;
+        uint attrs = gcx.getAttr(pool, biti);
+
+        size_t size = gcx.findSize(p);
+        bool has_pm = !(attrs & BlkAttr.NO_SCAN);
+        size_t pm_bitmask_size = 0;
+        if (has_pm)
+            pm_bitmask_size = (size_t*).sizeof;
+
+        if (opts.options.sentinel) {

             // Check for interior pointer
             // This depends on:
             // 1) size is a power of 2 for less than PAGESIZE values
             // 2) base of memory pool is aligned on PAGESIZE boundary
             if (cast(size_t)p & (size - 1) & (PAGESIZE - 1))
             // Check for interior pointer
             // This depends on:
             // 1) size is a power of 2 for less than PAGESIZE values
             // 2) base of memory pool is aligned on PAGESIZE boundary
             if (cast(size_t)p & (size - 1) & (PAGESIZE - 1))

-                size = 0;
-            return size ? size - SENTINEL_EXTRA : 0;
+                return 0;
+            return size - SENTINEL_EXTRA - pm_bitmask_size;

         }
         }

-        else
-        {
+        else {

             if (p == gcx.p_cache)
                 return gcx.size_cache;
 
             if (p == gcx.p_cache)
                 return gcx.size_cache;
 

-            size_t size = gcx.findSize(p);
-

             // Check for interior pointer
             // This depends on:
             // 1) size is a power of 2 for less than PAGESIZE values
             // 2) base of memory pool is aligned on PAGESIZE boundary
             if (cast(size_t)p & (size - 1) & (PAGESIZE - 1))
             // Check for interior pointer
             // This depends on:
             // 1) size is a power of 2 for less than PAGESIZE values
             // 2) base of memory pool is aligned on PAGESIZE boundary
             if (cast(size_t)p & (size - 1) & (PAGESIZE - 1))

-                size = 0;
-            else
-            {
-                gcx.p_cache = p;
-                gcx.size_cache = size;
-            }
+                return 0;

 
 

-            return size;
+            gcx.p_cache = p;
+            gcx.size_cache = size - pm_bitmask_size;
+
+            return gcx.size_cache;

         }
     }
 
         }
     }
 


@@ -920,7 +1012,8 @@ class GC
     {
         assert(p);
 
     {
         assert(p);
 

-        sentinel_Invariant(p);
+        if (opts.options.sentinel)
+            sentinel_Invariant(p);

         debug (PTRCHECK)
         {
             Pool*  pool;
         debug (PTRCHECK)
         {
             Pool*  pool;


@@ -928,7 +1021,8 @@ class GC
             Bins   bin;
             size_t size;
 
             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;
             pool = gcx.findPool(p);
             assert(pool);
             pagenum = cast(size_t)(p - pool.baseAddr) / PAGESIZE;


@@ -1159,7 +1253,7 @@ class GC
         size_t n;
         size_t bsize = 0;
 
         size_t n;
         size_t bsize = 0;
 

-        cstring.memset(&stats, 0, GCStats.sizeof);
+        memset(&stats, 0, GCStats.sizeof);

 
         for (n = 0; n < pools.length; n++)
         {
 
         for (n = 0; n < pools.length; n++)
         {


@@ -1578,10 +1672,12 @@ struct Gcx
             }
 
             ////////////////////////////////////////////////////////////////////
             }
 
             ////////////////////////////////////////////////////////////////////

-            // getBits
+            // getAttr

             ////////////////////////////////////////////////////////////////////
 
             ////////////////////////////////////////////////////////////////////
 

-            info.attr = getBits(pool, cast(size_t)(offset / 16));
+            info.attr = getAttr(pool, cast(size_t)(offset / 16));
+            if (!(info.attr & BlkAttr.NO_SCAN))
+                info.size -= (size_t*).sizeof;  // bitmask

         }
         return info;
     }
         }
         return info;
     }


@@ -1755,10 +1851,11 @@ struct Gcx
       L1:
         pool.pagetable[pn] = B_PAGE;
         if (npages > 1)
       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;
         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:
         return p;
 
       Lnomemory:


@@ -1853,38 +1950,61 @@ struct Gcx
     }
 
 
     }
 
 

+    /**
+     * Marks a range of memory using the conservative bit mask.  Used for
+     * the stack, for the data segment, and additional memory ranges.
+     */
+    void mark_conservative(void* pbot, void* ptop)
+    {
+        mark(pbot, ptop, PointerMap.init.bits.ptr);
+    }
+
+

     /**
      * Search a range of memory values and mark any pointers into the GC pool.
      */
     /**
      * Search a range of memory values and mark any pointers into the GC pool.
      */

-    void mark(void *pbot, void *ptop)
+    void mark(void *pbot, void *ptop, size_t* pm_bitmask)

     {
     {

+        const BITS_PER_WORD = size_t.sizeof * 8;
+

         void **p1 = cast(void **)pbot;
         void **p2 = cast(void **)ptop;
         size_t pcache = 0;
         uint changes = 0;
 
         void **p1 = cast(void **)pbot;
         void **p2 = cast(void **)ptop;
         size_t pcache = 0;
         uint changes = 0;
 

+        // TODO: add option to be conservative
+        // force conservative scanning
+        //pm_bitmask = PointerMap.init.bits.ptr;
+
+        size_t type_size = pm_bitmask[0];
+        size_t* pm_bits = pm_bitmask + 1;
+

         //printf("marking range: %p -> %p\n", pbot, ptop);
         //printf("marking range: %p -> %p\n", pbot, ptop);

-        for (; p1 < p2; p1++)
-        {
-            Pool *pool;
-            byte *p = cast(byte *)(*p1);
+        for (; p1 + type_size <= p2; p1 += type_size) {
+            for (size_t n = 0; n < type_size; n++) {
+                // scan bit set for this word
+                if (!(pm_bits[n / BITS_PER_WORD] & (1 << (n % BITS_PER_WORD))))
+                    continue;
+
+                void* p = *(p1 + n);
+
+                if (p < minAddr || p >= maxAddr)
+                    continue;

 
 

-            if (p >= minAddr && p < maxAddr)
-            {

                 if ((cast(size_t)p & ~(PAGESIZE-1)) == pcache)
                     continue;
 
                 if ((cast(size_t)p & ~(PAGESIZE-1)) == pcache)
                     continue;
 

-                pool = findPool(p);
+                Pool* pool = findPool(p);

                 if (pool)
                 {
                     size_t offset = cast(size_t)(p - pool.baseAddr);
                 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)
                     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
                     else if (bin == B_PAGEPLUS)
                     {
                         do


@@ -1892,7 +2012,7 @@ struct Gcx
                             --pn;
                         }
                         while (cast(Bins)pool.pagetable[pn] == B_PAGEPLUS);
                             --pn;
                         }
                         while (cast(Bins)pool.pagetable[pn] == B_PAGEPLUS);

-                        biti = pn * (PAGESIZE / 16);
+                        bit_i = pn * (PAGESIZE / 16);

                     }
                     else
                     {
                     }
                     else
                     {


@@ -1903,12 +2023,12 @@ struct Gcx
                     if (bin >= B_PAGE) // Cache B_PAGE and B_PAGEPLUS lookups
                         pcache = cast(size_t)p & ~(PAGESIZE-1);
 
                     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;
                         }
                     }
                             changes = 1;
                         }
                     }


@@ -1918,12 +2038,15 @@ struct Gcx
         anychanges |= changes;
     }
 
         anychanges |= changes;
     }
 

-

     /**
      * Return number of full pages free'd.
      */
     size_t fullcollectshell()
     {
     /**
      * 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;
         // The purpose of the 'shell' is to ensure all the registers
         // get put on the stack so they'll be scanned
         void *sp;


@@ -2017,6 +2140,7 @@ struct Gcx
         debug(COLLECT_PRINTF) printf("Gcx.fullcollect()\n");
 
         thread_suspendAll();
         debug(COLLECT_PRINTF) printf("Gcx.fullcollect()\n");
 
         thread_suspendAll();

+        stats.world_stopped();

 
         p_cache = null;
         size_cache = 0;
 
         p_cache = null;
         size_cache = 0;


@@ -2047,17 +2171,17 @@ struct Gcx
             pool.mark.copy(&pool.freebits);
         }
 
             pool.mark.copy(&pool.freebits);
         }
 

-        rt_scanStaticData( &mark );
+        rt_scanStaticData( &mark_conservative );

 
         if (!noStack)
         {
             // Scan stacks and registers for each paused thread
 
         if (!noStack)
         {
             // Scan stacks and registers for each paused thread

-            thread_scanAll( &mark, stackTop );
+            thread_scanAll( &mark_conservative, stackTop );

         }
 
         // Scan roots
         debug(COLLECT_PRINTF) printf("scan roots[]\n");
         }
 
         // Scan roots
         debug(COLLECT_PRINTF) printf("scan roots[]\n");

-        mark(roots.ptr, roots.ptr + roots.length);
+        mark_conservative(roots.ptr, roots.ptr + roots.length);

 
         // Scan ranges
         debug(COLLECT_PRINTF) printf("scan ranges[]\n");
 
         // Scan ranges
         debug(COLLECT_PRINTF) printf("scan ranges[]\n");


@@ -2065,7 +2189,7 @@ struct Gcx
         for (n = 0; n < ranges.length; n++)
         {
             debug(COLLECT_PRINTF) printf("\t%x .. %x\n", ranges[n].pbot, ranges[n].ptop);
         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);
+            mark_conservative(ranges[n].pbot, ranges[n].ptop);

         }
         //log--;
 
         }
         //log--;
 


@@ -2112,9 +2236,11 @@ struct Gcx
 
                         pn = cast(size_t)(o - pool.baseAddr) / PAGESIZE;
                         bin = cast(Bins)pool.pagetable[pn];
 
                         pn = cast(size_t)(o - pool.baseAddr) / PAGESIZE;
                         bin = cast(Bins)pool.pagetable[pn];

-                        if (bin < B_PAGE)
-                        {
-                            mark(o, o + binsize[bin]);
+                        if (bin < B_PAGE) {
+                            auto end_of_blk = cast(size_t**)(o + binsize[bin] -
+                                    (size_t*).sizeof);
+                            size_t* pm_bitmask = *end_of_blk;
+                            mark(o, end_of_blk, pm_bitmask);

                         }
                         else if (bin == B_PAGE || bin == B_PAGEPLUS)
                         {
                         }
                         else if (bin == B_PAGE || bin == B_PAGEPLUS)
                         {


@@ -2124,9 +2250,15 @@ struct Gcx
                                     pn--;
                             }
                             u = 1;
                                     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++;
                                 u++;

-                            mark(o, o + u * PAGESIZE);
+
+                            size_t blk_size = u * PAGESIZE;
+                            auto end_of_blk = cast(size_t**)(o + blk_size -
+                                    (size_t*).sizeof);
+                            size_t* pm_bitmask = *end_of_blk;
+                            mark(o, end_of_blk, pm_bitmask);

                         }
                     }
                 }
                         }
                     }
                 }


@@ -2134,6 +2266,7 @@ struct Gcx
         }
 
         thread_resumeAll();
         }
 
         thread_resumeAll();

+        stats.world_started();

 
         // Free up everything not marked
         debug(COLLECT_PRINTF) printf("\tfree'ing\n");
 
         // Free up everything not marked
         debug(COLLECT_PRINTF) printf("\tfree'ing\n");


@@ -2153,44 +2286,56 @@ struct Gcx
                     auto size = binsize[bin];
                     byte* p = pool.baseAddr + pn * PAGESIZE;
                     byte* ptop = p + PAGESIZE;
                     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
 
     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;
 
 
                             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;
                     }
     }
                         }
                         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;
 
 
                             List *list = cast(List *)p;
 

-                            debug (MEMSTOMP) cstring.memset(p, 0xF3, size);
+                            if (opts.options.mem_stomp)
+                                memset(p, 0xF3, size);

 
                             freed += size;
                         }
 
                             freed += size;
                         }


@@ -2198,29 +2343,35 @@ struct Gcx
                 }
                 else if (bin == B_PAGE)
                 {
                 }
                 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;
                     {
                         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(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++;
 
                         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;
                             {
                                 p += PAGESIZE;

-                                cstring.memset(p, 0xF3, PAGESIZE);
+                                memset(p, 0xF3, PAGESIZE);

                             }
                         }
                     }
                             }
                         }
                     }


@@ -2240,21 +2391,21 @@ struct Gcx
             for (size_t pn = 0; pn < pool.npages; pn++)
             {
                 Bins   bin = cast(Bins)pool.pagetable[pn];
             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 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;
 
                     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;
                             goto Lnotfree;
                     }
                     pool.pagetable[pn] = B_FREE;


@@ -2265,11 +2416,12 @@ struct Gcx
                     p = pool.baseAddr + pn * PAGESIZE;
                     for (u = 0; u < PAGESIZE; u += size)
                     {
                     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);
                         {
                             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;
                         }
                                 list.next = bucket[bin];
                             bucket[bin] = list;
                         }


@@ -2288,31 +2440,31 @@ struct Gcx
     /**
      *
      */
     /**
      *
      */

-    uint getBits(Pool* pool, size_t biti)
+    uint getAttr(Pool* pool, size_t bit_i)

     in
     {
         assert( pool );
     }
     body
     {
     in
     {
         assert( pool );
     }
     body
     {

-        uint bits;
+        uint attrs;

 
         if (pool.finals.nbits &&
 
         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 &&
 //        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 );
     in
     {
         assert( pool );


@@ -2323,17 +2475,17 @@ struct Gcx
         {
             if (!pool.finals.nbits)
                 pool.finals.alloc(pool.mark.nbits);
         {
             if (!pool.finals.nbits)
                 pool.finals.alloc(pool.mark.nbits);

-            pool.finals.set(biti);
+            pool.finals.set(bit_i);

         }
         if (mask & BlkAttr.NO_SCAN)
         {
         }
         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);
         }
 //        if (mask & BlkAttr.NO_MOVE)
 //        {
 //            if (!pool.nomove.nbits)
 //                pool.nomove.alloc(pool.mark.nbits);

-//            pool.nomove.set(biti);
+//            pool.nomove.set(bit_i);

 //        }
     }
 
 //        }
     }
 


@@ -2341,7 +2493,7 @@ struct Gcx
     /**
      *
      */
     /**
      *
      */

-    void clrBits(Pool* pool, size_t biti, uint mask)
+    void clrAttr(Pool* pool, size_t bit_i, uint mask)

     in
     {
         assert( pool );
     in
     {
         assert( pool );


@@ -2349,11 +2501,11 @@ struct Gcx
     body
     {
         if (mask & BlkAttr.FINALIZE && pool.finals.nbits)
     body
     {
         if (mask & BlkAttr.FINALIZE && pool.finals.nbits)

-            pool.finals.clear(biti);
+            pool.finals.clear(bit_i);

         if (mask & BlkAttr.NO_SCAN)
         if (mask & BlkAttr.NO_SCAN)

-            pool.noscan.clear(biti);
+            pool.noscan.clear(bit_i);

 //        if (mask & BlkAttr.NO_MOVE && pool.nomove.nbits)
 //        if (mask & BlkAttr.NO_MOVE && pool.nomove.nbits)

-//            pool.nomove.clear(biti);
+//            pool.nomove.clear(bit_i);

     }
 
 }
     }
 
 }


@@ -2401,7 +2553,7 @@ struct Pool
         pagetable = cast(ubyte*) cstdlib.malloc(npages);
         if (!pagetable)
             onOutOfMemoryError();
         pagetable = cast(ubyte*) cstdlib.malloc(npages);
         if (!pagetable)
             onOutOfMemoryError();

-        cstring.memset(pagetable, B_FREE, npages);
+        memset(pagetable, B_FREE, npages);

 
         this.npages = npages;
     }
 
         this.npages = npages;
     }


@@ -2490,7 +2642,7 @@ struct Pool
      */
     void freePages(size_t pagenum, size_t npages)
     {
      */
     void freePages(size_t pagenum, size_t npages)
     {

-        cstring.memset(&pagetable[pagenum], B_FREE, npages);
+        memset(&pagetable[pagenum], B_FREE, npages);

     }
 
 
     }
 
 


@@ -2510,69 +2662,40 @@ struct Pool
 /* ============================ SENTINEL =============================== */
 
 
 /* ============================ 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;

 }
 
 
 }