diff -r 000000000000 -r 6474c204b198 memory/build/mozjemalloc_compat.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/memory/build/mozjemalloc_compat.c	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,98 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZ_JEMALLOC3
+#  error Should only compile this file when building with jemalloc 3
+#endif
+
+#define MOZ_JEMALLOC_IMPL
+
+#include "mozmemory_wrap.h"
+#include "jemalloc_types.h"
+#include "mozilla/Types.h"
+
+#if defined(MOZ_NATIVE_JEMALLOC)
+
+MOZ_IMPORT_API int
+je_(mallctl)(const char*, void*, size_t*, void*, size_t);
+MOZ_IMPORT_API int
+je_(mallctlnametomib)(const char *name, size_t *mibp, size_t *miblenp);
+MOZ_IMPORT_API int
+je_(mallctlbymib)(const size_t *mib, size_t miblen, void *oldp, size_t *oldlenp, void *newp, size_t newlen);
+MOZ_IMPORT_API int
+je_(nallocm)(size_t *rsize, size_t size, int flags);
+
+#else
+#  include "jemalloc/jemalloc.h"
+#endif
+
+/*
+ *  CTL_* macros are from memory/jemalloc/src/src/stats.c with changes:
+ *  - drop `t' argument to avoid redundancy in calculating type size
+ *  - require `i' argument for arena number explicitly
+ */
+
+#define	CTL_GET(n, v) do {						\
+	size_t sz = sizeof(v);						\
+	je_(mallctl)(n, &v, &sz, NULL, 0);				\
+} while (0)
+
+#define	CTL_I_GET(n, v, i) do {						\
+	size_t mib[6];							\
+	size_t miblen = sizeof(mib) / sizeof(mib[0]);			\
+	size_t sz = sizeof(v);						\
+	je_(mallctlnametomib)(n, mib, &miblen);			\
+	mib[2] = i;							\
+	je_(mallctlbymib)(mib, miblen, &v, &sz, NULL, 0);		\
+} while (0)
+
+MOZ_MEMORY_API size_t
+malloc_good_size_impl(size_t size)
+{
+  size_t ret;
+  /* je_nallocm crashes when given a size of 0. As
+   * malloc_usable_size(malloc(0)) and malloc_usable_size(malloc(1))
+   * return the same value, use a size of 1. */
+  if (size == 0)
+    size = 1;
+  if (!je_(nallocm)(&ret, size, 0))
+    return ret;
+  return size;
+}
+
+MOZ_JEMALLOC_API void
+jemalloc_stats_impl(jemalloc_stats_t *stats)
+{
+  unsigned narenas;
+  size_t active, allocated, mapped, page, pdirty;
+
+  CTL_GET("arenas.narenas", narenas);
+  CTL_GET("arenas.page", page);
+  CTL_GET("stats.active", active);
+  CTL_GET("stats.allocated", allocated);
+  CTL_GET("stats.mapped", mapped);
+
+  /* get the summation for all arenas, i == narenas */
+  CTL_I_GET("stats.arenas.0.pdirty", pdirty, narenas);
+
+  stats->mapped = mapped;
+  stats->allocated = allocated;
+  stats->waste = active - allocated;
+  stats->page_cache = pdirty * page;
+
+  // We could get this value out of base.c::base_pages, but that really should
+  // be an upstream change, so don't worry about it for now.
+  stats->bookkeeping = 0;
+}
+
+MOZ_JEMALLOC_API void
+jemalloc_purge_freed_pages_impl()
+{
+}
+
+MOZ_JEMALLOC_API void
+jemalloc_free_dirty_pages_impl()
+{
+  je_(mallctl)("arenas.purge", NULL, 0, NULL, 0);
+}