sanity: fix places where we weren't filling fresh memory with 0xaa

[ghc-hetmet.git] / rts / sm / BlockAlloc.c

diff --git a/rts/sm/BlockAlloc.c b/rts/sm/BlockAlloc.c
index 484c0d4..429ebd0 100644 (file)
--- a/rts/sm/BlockAlloc.c
+++ b/rts/sm/BlockAlloc.c
@@ -21,6 +21,7 @@
 #include "Storage.h"
 #include "RtsUtils.h"
 #include "BlockAlloc.h"
+#include "OSMem.h"
 
 #include <string.h>
 
@@ -118,6 +119,16 @@ static void  initMBlock(void *mblock);
 
   --------------------------------------------------------------------------- */
 
+/* ---------------------------------------------------------------------------
+   WATCH OUT FOR OVERFLOW
+
+   Be very careful with integer overflow here.  If you have an
+   expression like (n_blocks * BLOCK_SIZE), and n_blocks is an int or
+   a nat, then it will very likely overflow on a 64-bit platform.
+   Always cast to StgWord (or W_ for short) first: ((W_)n_blocks * BLOCK_SIZE).
+
+  --------------------------------------------------------------------------- */
+
 #define MAX_FREE_LIST 9
 
 // In THREADED_RTS mode, the free list is protected by sm_mutex.
@@ -322,6 +333,7 @@ allocGroup (nat n)
         // only the bdescrs of the first MB are required to be initialised
         initGroup(bd);
 
+        IF_DEBUG(sanity,memset(bd->start, 0xaa, bd->blocks * BLOCK_SIZE));
         IF_DEBUG(sanity, checkFreeListSanity());
         return bd;
     }
@@ -337,7 +349,7 @@ allocGroup (nat n)
 
     if (ln == MAX_FREE_LIST) {
 #if 0
-        if ((mblocks_allocated * MBLOCK_SIZE_W - n_alloc_blocks * BLOCK_SIZE_W) > (1024*1024)/sizeof(W_)) {
+        if (((W_)mblocks_allocated * MBLOCK_SIZE_W - (W_)n_alloc_blocks * BLOCK_SIZE_W) > (1024*1024)/sizeof(W_)) {
             debugBelch("Fragmentation, wanted %d blocks:", n);
             RtsFlags.DebugFlags.block_alloc = 1;
             checkFreeListSanity();
@@ -371,6 +383,7 @@ allocGroup (nat n)
         barf("allocGroup: free list corrupted");
     }
     initGroup(bd);             // initialise it
+    IF_DEBUG(sanity,memset(bd->start, 0xaa, bd->blocks * BLOCK_SIZE));
     IF_DEBUG(sanity, checkFreeListSanity());
     ASSERT(bd->blocks == n);
     return bd;
@@ -472,7 +485,7 @@ freeGroup(bdescr *p)
   p->gen = NULL;
   p->gen_no = 0;
   /* fill the block group with garbage if sanity checking is on */
-  IF_DEBUG(sanity,memset(p->start, 0xaa, p->blocks * BLOCK_SIZE));
+  IF_DEBUG(sanity,memset(p->start, 0xaa, (W_)p->blocks * BLOCK_SIZE));
 
   if (p->blocks == 0) barf("freeGroup: block size is zero");
 
@@ -586,7 +599,7 @@ splitBlockGroup (bdescr *bd, nat blocks)
         low_mblocks = 1 + (blocks - BLOCKS_PER_MBLOCK) / (MBLOCK_SIZE / BLOCK_SIZE);
         high_mblocks = (bd->blocks - blocks) / (MBLOCK_SIZE / BLOCK_SIZE);
 
-        new_mblock = (void *) ((P_)MBLOCK_ROUND_DOWN(bd) + low_mblocks * MBLOCK_SIZE_W);
+        new_mblock = (void *) ((P_)MBLOCK_ROUND_DOWN(bd) + (W_)low_mblocks * MBLOCK_SIZE_W);
         initMBlock(new_mblock);
         new_bd = FIRST_BDESCR(new_mblock);
         new_bd->blocks = MBLOCK_GROUP_BLOCKS(high_mblocks);
@@ -661,6 +674,41 @@ countAllocdBlocks(bdescr *bd)
     return n;
 }
 
+void returnMemoryToOS(nat n /* megablocks */)
+{
+    static bdescr *bd;
+    nat size;
+
+    bd = free_mblock_list;
+    while ((n > 0) && (bd != NULL)) {
+        size = BLOCKS_TO_MBLOCKS(bd->blocks);
+        if (size > n) {
+            nat newSize = size - n;
+            char *freeAddr = MBLOCK_ROUND_DOWN(bd->start);
+            freeAddr += newSize * MBLOCK_SIZE;
+            bd->blocks = MBLOCK_GROUP_BLOCKS(newSize);
+            freeMBlocks(freeAddr, n);
+            n = 0;
+        }
+        else {
+            char *freeAddr = MBLOCK_ROUND_DOWN(bd->start);
+            n -= size;
+            bd = bd->link;
+            freeMBlocks(freeAddr, size);
+        }
+    }
+    free_mblock_list = bd;
+
+    osReleaseFreeMemory();
+
+    IF_DEBUG(gc,
+        if (n != 0) {
+            debugBelch("Wanted to free %d more MBlocks than are freeable\n",
+                       n);
+        }
+    );
+}
+
 /* -----------------------------------------------------------------------------
    Debugging
    -------------------------------------------------------------------------- */