Revert r16648, r16641, r16638 and r16637.

src/platform-macos.cc

Index: src/platform-macos.cc
diff --git a/src/platform-macos.cc b/src/platform-macos.cc
index 7a2249c0e906235b102069bdece73f00c489194a..67cc96f93790a93692bce5f9ad0e51d66a328af9 100644
--- a/src/platform-macos.cc
+++ b/src/platform-macos.cc
@@ -79,6 +79,34 @@ namespace v8 {
 namespace internal {
 
 
+// Constants used for mmap.
+// kMmapFd is used to pass vm_alloc flags to tag the region with the user
+// defined tag 255 This helps identify V8-allocated regions in memory analysis
+// tools like vmmap(1).
+static const int kMmapFd = VM_MAKE_TAG(255);
+static const off_t kMmapFdOffset = 0;
+
+
+void* OS::Allocate(const size_t requested,
+                   size_t* allocated,
+                   bool is_executable) {
+  const size_t msize = RoundUp(requested, getpagesize());
+  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
+  void* mbase = mmap(OS::GetRandomMmapAddr(),
+                     msize,
+                     prot,
+                     MAP_PRIVATE | MAP_ANON,
+                     kMmapFd,
+                     kMmapFdOffset);
+  if (mbase == MAP_FAILED) {
+    LOG(Isolate::Current(), StringEvent("OS::Allocate", "mmap failed"));
+    return NULL;
+  }
+  *allocated = msize;
+  return mbase;
+}
+
+
 void OS::DumpBacktrace() {
   // If weak link to execinfo lib has failed, ie because we are on 10.4, abort.
   if (backtrace == NULL) return;
@@ -109,7 +137,7 @@ OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
   int size = ftell(file);
 
   void* memory =
-      mmap(NULL,
+      mmap(OS::GetRandomMmapAddr(),
            size,
            PROT_READ | PROT_WRITE,
            MAP_SHARED,
@@ -129,7 +157,7 @@ OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size,
     return NULL;
   }
   void* memory =
-      mmap(NULL,
+      mmap(OS::GetRandomMmapAddr(),
           size,
           PROT_READ | PROT_WRITE,
           MAP_SHARED,
@@ -140,7 +168,7 @@ OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size,
 
 
 PosixMemoryMappedFile::~PosixMemoryMappedFile() {
-  if (memory_) munmap(memory_, size_);
+  if (memory_) OS::Free(memory_, size_);
   fclose(file_);
 }
 
@@ -199,4 +227,137 @@ int OS::StackWalk(Vector<StackFrame> frames) {
   return POSIXBacktraceHelper<backtrace, backtrace_symbols>::StackWalk(frames);
 }
 
+
+VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }
+
+
+VirtualMemory::VirtualMemory(size_t size)
+    : address_(ReserveRegion(size)), size_(size) { }
+
+
+VirtualMemory::VirtualMemory(size_t size, size_t alignment)
+    : address_(NULL), size_(0) {
+  ASSERT(IsAligned(alignment, static_cast<intptr_t>(OS::AllocateAlignment())));
+  size_t request_size = RoundUp(size + alignment,
+                                static_cast<intptr_t>(OS::AllocateAlignment()));
+  void* reservation = mmap(OS::GetRandomMmapAddr(),
+                           request_size,
+                           PROT_NONE,
+                           MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
+                           kMmapFd,
+                           kMmapFdOffset);
+  if (reservation == MAP_FAILED) return;
+
+  Address base = static_cast<Address>(reservation);
+  Address aligned_base = RoundUp(base, alignment);
+  ASSERT_LE(base, aligned_base);
+
+  // Unmap extra memory reserved before and after the desired block.
+  if (aligned_base != base) {
+    size_t prefix_size = static_cast<size_t>(aligned_base - base);
+    OS::Free(base, prefix_size);
+    request_size -= prefix_size;
+  }
+
+  size_t aligned_size = RoundUp(size, OS::AllocateAlignment());
+  ASSERT_LE(aligned_size, request_size);
+
+  if (aligned_size != request_size) {
+    size_t suffix_size = request_size - aligned_size;
+    OS::Free(aligned_base + aligned_size, suffix_size);
+    request_size -= suffix_size;
+  }
+
+  ASSERT(aligned_size == request_size);
+
+  address_ = static_cast<void*>(aligned_base);
+  size_ = aligned_size;
+}
+
+
+VirtualMemory::~VirtualMemory() {
+  if (IsReserved()) {
+    bool result = ReleaseRegion(address(), size());
+    ASSERT(result);
+    USE(result);
+  }
+}
+
+
+bool VirtualMemory::IsReserved() {
+  return address_ != NULL;
+}
+
+
+void VirtualMemory::Reset() {
+  address_ = NULL;
+  size_ = 0;
+}
+
+
+bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
+  return CommitRegion(address, size, is_executable);
+}
+
+
+bool VirtualMemory::Uncommit(void* address, size_t size) {
+  return UncommitRegion(address, size);
+}
+
+
+bool VirtualMemory::Guard(void* address) {
+  OS::Guard(address, OS::CommitPageSize());
+  return true;
+}
+
+
+void* VirtualMemory::ReserveRegion(size_t size) {
+  void* result = mmap(OS::GetRandomMmapAddr(),
+                      size,
+                      PROT_NONE,
+                      MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
+                      kMmapFd,
+                      kMmapFdOffset);
+
+  if (result == MAP_FAILED) return NULL;
+
+  return result;
+}
+
+
+bool VirtualMemory::CommitRegion(void* address,
+                                 size_t size,
+                                 bool is_executable) {
+  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
+  if (MAP_FAILED == mmap(address,
+                         size,
+                         prot,
+                         MAP_PRIVATE | MAP_ANON | MAP_FIXED,
+                         kMmapFd,
+                         kMmapFdOffset)) {
+    return false;
+  }
+  return true;
+}
+
+
+bool VirtualMemory::UncommitRegion(void* address, size_t size) {
+  return mmap(address,
+              size,
+              PROT_NONE,
+              MAP_PRIVATE | MAP_ANON | MAP_NORESERVE | MAP_FIXED,
+              kMmapFd,
+              kMmapFdOffset) != MAP_FAILED;
+}
+
+
+bool VirtualMemory::ReleaseRegion(void* address, size_t size) {
+  return munmap(address, size) == 0;
+}
+
+
+bool VirtualMemory::HasLazyCommits() {
+  return false;
+}
+
 } }  // namespace v8::internal