Major changes to the Chrome allocator....

third_party/tcmalloc/allocator_shim.cc

+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <config.h>
+
+// When defined, different heap allocators can be used via an environment
+// variable set before running the program.  This may reduce the amount
+// of inlining that we get with malloc/free/etc.  Disabling makes it
+// so that only tcmalloc can be used.
+#define ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
+
+// TODO(mbelshe): Ensure that all calls to tcmalloc have the proper call depth
+// from the "user code" so that debugging tools (HeapChecker) can work.
+
+// __THROW is defined in glibc systems.  It means, counter-intuitively,
+// "This function will never throw an exception."  It's an optional
+// optimization tool, but we may need to use it to match glibc prototypes.
+#ifndef __THROW    // I guess we're not on a glibc system
+# define __THROW   // __THROW is just an optimization, so ok to make it ""
+#endif
+
+// new_mode behaves similarly to MSVC's _set_new_mode.
+// If flag is 0 (default), calls to malloc will behave normally.
+// If flag is 1, calls to malloc will behave like calls to new,
+// and the std_new_handler will be invoked on failure.
+// Can be set by calling _set_new_mode().
+static int new_mode = 0;
+
+typedef enum {
+  TCMALLOC,    // TCMalloc is the default allocator.
+  JEMALLOC,    // JEMalloc
+  WINDEFAULT,  // Windows Heap
+  WINLFH,      // Windows LFH Heap
+} Allocator;
+
+// This is the default allocator.
+static Allocator allocator = TCMALLOC;
+
+// We include tcmalloc and the win_allocator to get as much inlining as
+// possible.
+#include "tcmalloc.cc"
+#include "win_allocator.cc"
+
+// Forward declarations from jemalloc.
+extern "C" {
+void* je_malloc(size_t s);
+void* je_realloc(void* p, size_t s);
+void je_free(void* s);
+size_t je_msize(void* p);
+bool je_malloc_init_hard();
+}
+
+extern "C" {
+
+// Call the new handler, if one has been set.
+// Returns true on successfully calling the handler, false otherwise.
+inline bool call_new_handler(bool nothrow) {
+  // Get the current new handler.  NB: this function is not
+  // thread-safe.  We make a feeble stab at making it so here, but
+  // this lock only protects against tcmalloc interfering with
+  // itself, not with other libraries calling set_new_handler.
+  std::new_handler nh;
+  {
+    SpinLockHolder h(&set_new_handler_lock);
+    nh = std::set_new_handler(0);
+    (void) std::set_new_handler(nh);
+  }
+#if (defined(__GNUC__) && !defined(__EXCEPTIONS)) || (defined(_HAS_EXCEPTIONS) && !_HAS_EXCEPTIONS)
+  if (!nh)
+    return false;
+  // Since exceptions are disabled, we don't really know if new_handler
+  // failed.  Assume it will abort if it fails.
+  (*nh)();
+  return true;
+#else
+  // If no new_handler is established, the allocation failed.
+  if (!nh) {
+    if (nothrow)
+      return 0;
+    throw std::bad_alloc();
+  }
+  // Otherwise, try the new_handler.  If it returns, retry the
+  // allocation.  If it throws std::bad_alloc, fail the allocation.
+  // if it throws something else, don't interfere.
+  try {
+    (*nh)();
+  } catch (const std::bad_alloc&) {
+    if (!nothrow)
+      throw;
+    return p;
+  }
+#endif  // (defined(__GNUC__) && !defined(__EXCEPTIONS)) || (defined(_HAS_EXCEPTIONS) && !_HAS_EXCEPTIONS)
+}
+
+void* malloc(size_t size) __THROW {
+  void* ptr;
+  for (;;) {
+#ifdef ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
+    switch (allocator) {
+      case JEMALLOC:
+        ptr = je_malloc(size);
+        break;
+      case WINDEFAULT:
+      case WINLFH:
+        ptr = win_heap_malloc(size);
+        break;
+      case TCMALLOC:
+      default:
+        ptr = do_malloc(size);
+        break;
+    }
+#else
+    // TCMalloc case.
+    ptr = do_malloc(size);
+#endif
+    if (ptr)
+      return ptr;
+
+    if (!new_mode || !call_new_handler(true))
+      break;
+  }
+  return ptr;
+}
+
+void free(void* p) __THROW {
+#ifdef ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
+  switch (allocator) {
+    case JEMALLOC:
+      je_free(p);
+      return;
+    case WINDEFAULT:
+    case WINLFH:
+      win_heap_free(p);
+      return;
+  }
+#endif
+  // TCMalloc case.
+  do_free(p);
+}
+
+void* realloc(void* ptr, size_t size) __THROW {
+  void* new_ptr;
+  for (;;) {
+#ifdef ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
+    switch (allocator) {
+      case JEMALLOC:
+        new_ptr = je_realloc(ptr, size);
+        break;
+      case WINDEFAULT:
+      case WINLFH:
+        new_ptr = win_heap_realloc(ptr, size);
+        break;
+      case TCMALLOC:
+      default:
+        new_ptr = do_realloc(ptr, size);
+        break;
+    }
+#else
+    // TCMalloc case.
+    new_ptr = do_realloc(ptr, size);
+#endif
+    if (new_ptr)
+      return new_ptr;
+    if (!new_mode || !call_new_handler(true))
+      break;
+  }
+  return new_ptr;
+}
+
+// TODO(mbelshe): Implement this for other allocators.
+void malloc_stats(void) __THROW {
+#ifdef ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
+  switch (allocator) {
+    case JEMALLOC:
+      // No stats.
+      return;
+    case WINDEFAULT:
+    case WINLFH:
+      // No stats.
+      return;
+  }
+#endif
+  tc_malloc_stats();
+}
+
+#ifdef WIN32
+
+extern "C" size_t _msize(void* p) {
+#ifdef ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
+  switch (allocator) {
+    case JEMALLOC:
+      return je_msize(p);
+    case WINDEFAULT:
+    case WINLFH:
+      return win_heap_msize(p);
+  }
+#endif
+  return MallocExtension::instance()->GetAllocatedSize(p);
+}
+
+// This is included to resolve references from libcmt.
+extern "C" intptr_t _get_heap_handle() {
+  return 0;
+}
+
+// The CRT heap initialization stub.
+extern "C" int _heap_init() {
+#ifdef ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
+  const char* override = GetenvBeforeMain("CHROME_ALLOCATOR");
+  if (override) {
+    if (!stricmp(override, "jemalloc"))
+      allocator = JEMALLOC;
+    else if (!stricmp(override, "winheap"))
+      allocator = WINDEFAULT;
+    else if (!stricmp(override, "winlfh"))
+      allocator = WINLFH;
+    else if (!stricmp(override, "tcmalloc"))
+      allocator = TCMALLOC;
+  }
+
+  switch (allocator) {
+    case JEMALLOC:
+      return je_malloc_init_hard() ? 0 : 1;
+    case WINDEFAULT:
+      return win_heap_init(false) ? 1 : 0;
+    case WINLFH:
+      return win_heap_init(true) ? 1 : 0;
+    case TCMALLOC:
+    default:
+      // fall through
+      break;
+  }
+#endif
+  // Initializing tcmalloc.
+  // We intentionally leak this object.  It lasts for the process
+  // lifetime.  Trying to teardown at _heap_term() is so late that
+  // you can't do anything useful anyway.
+  new TCMallocGuard();
+  return 1;
+}
+
+// The CRT heap cleanup stub.
+extern "C" void _heap_term() {}
+
+// We set this to 1 because part of the CRT uses a check of _crtheap != 0
+// to test whether the CRT has been initialized.  Once we've ripped out
+// the allocators from libcmt, we need to provide this definition so that
+// the rest of the CRT is still usable.
+extern "C" void* _crtheap = reinterpret_cast<void*>(1);
+
+#endif  // WIN32
+
+#include "generic_allocators.cc"
+
+}  // extern C