Bug 1423000 - Remove Replay::Commit. r=njn

It adds an uncompressible and noticeable time overhead to replaying
logs, even when one is not interested in measuring RSS. This has caused
me to clear the method body on multiple occasions.

If necessary, it is possible to enable zero or junk at the allocator
level for the same effect.

--HG--
extra : rebase_source : a4c44e97986668e712b500266d7fffe985e85881

memory/replace/logalloc/replay/Replay.cpp

@@ -80,14 +80,13 @@ private:
 struct MemSlot
 {
   void* mPtr;
-  size_t mSize;
 };
 
 /* An almost infinite list of slots.
  * In essence, this is a linked list of arrays of groups of slots.
- * Each group is 1MB. On 64-bits, one group allows to store 64k allocations.
+ * Each group is 1MB. On 64-bits, one group allows to store 128k allocations.
  * Each MemSlotList instance can store 1023 such groups, which means more
- * than 65M allocations. In case more would be needed, we chain to another
+ * than 130M allocations. In case more would be needed, we chain to another
  * MemSlotList, and so on.
  * Using 1023 groups makes the MemSlotList itself page sized on 32-bits
  * and 2 pages-sized on 64-bits.
@@ -343,8 +342,6 @@ public:
     mOps++;
     size_t size = parseNumber(aArgs);
     aSlot.mPtr = ::malloc_impl(size);
-    aSlot.mSize = size;
-    Commit(aSlot);
   }
 
   void posix_memalign(MemSlot& aSlot, Buffer& aArgs)
@@ -355,12 +352,9 @@ public:
     void* ptr;
     if (::posix_memalign_impl(&ptr, alignment, size) == 0) {
       aSlot.mPtr = ptr;
-      aSlot.mSize = size;
     } else {
       aSlot.mPtr = nullptr;
-      aSlot.mSize = 0;
     }
-    Commit(aSlot);
   }
 
   void aligned_alloc(MemSlot& aSlot, Buffer& aArgs)
@@ -369,8 +363,6 @@ public:
     size_t alignment = parseNumber(aArgs.SplitChar(','));
     size_t size = parseNumber(aArgs);
     aSlot.mPtr = ::aligned_alloc_impl(alignment, size);
-    aSlot.mSize = size;
-    Commit(aSlot);
   }
 
   void calloc(MemSlot& aSlot, Buffer& aArgs)
@@ -379,8 +371,6 @@ public:
     size_t num = parseNumber(aArgs.SplitChar(','));
     size_t size = parseNumber(aArgs);
     aSlot.mPtr = ::calloc_impl(num, size);
-    aSlot.mSize = size * num;
-    Commit(aSlot);
   }
 
   void realloc(MemSlot& aSlot, Buffer& aArgs)
@@ -395,10 +385,7 @@ public:
     MemSlot& old_slot = (*this)[slot_id];
     void* old_ptr = old_slot.mPtr;
     old_slot.mPtr = nullptr;
-    old_slot.mSize = 0;
     aSlot.mPtr = ::realloc_impl(old_ptr, size);
-    aSlot.mSize = size;
-    Commit(aSlot);
   }
 
   void free(Buffer& aArgs)
@@ -412,7 +399,6 @@ public:
     MemSlot& slot = (*this)[slot_id];
     ::free_impl(slot.mPtr);
     slot.mPtr = nullptr;
-    slot.mSize = 0;
   }
 
   void memalign(MemSlot& aSlot, Buffer& aArgs)
@@ -421,8 +407,6 @@ public:
     size_t alignment = parseNumber(aArgs.SplitChar(','));
     size_t size = parseNumber(aArgs);
     aSlot.mPtr = ::memalign_impl(alignment, size);
-    aSlot.mSize = size;
-    Commit(aSlot);
   }
 
   void valloc(MemSlot& aSlot, Buffer& aArgs)
@@ -430,8 +414,6 @@ public:
     mOps++;
     size_t size = parseNumber(aArgs);
     aSlot.mPtr = ::valloc_impl(size);
-    aSlot.mSize = size;
-    Commit(aSlot);
   }
 
   void jemalloc_stats(Buffer& aArgs)
@@ -451,11 +433,6 @@ public:
   }
 
 private:
-  void Commit(MemSlot& aSlot)
-  {
-    memset(aSlot.mPtr, 0x5a, aSlot.mSize);
-  }
-
   intptr_t mStdErr;
   size_t mOps;
   MemSlotList mSlots;