Revert r16648, r16641, r16638 and r16637.

src/platform-win32.cc

Index: src/platform-win32.cc
diff --git a/src/platform-win32.cc b/src/platform-win32.cc
index 8f188a057f1a8a7ca2595280fe4121258ba5fd3b..ea4f7ea11f4177bdbee4f5de2dca570e50985741 100644
--- a/src/platform-win32.cc
+++ b/src/platform-win32.cc
@@ -69,6 +69,11 @@ int strncasecmp(const char* s1, const char* s2, int n) {
 #define _TRUNCATE 0
 #define STRUNCATE 80
 
+inline void MemoryBarrier() {
+  int barrier = 0;
+  __asm__ __volatile__("xchgl %%eax,%0 ":"=r" (barrier));
+}
+
 #endif  // __MINGW64_VERSION_MAJOR
 
 
@@ -123,6 +128,11 @@ int strncpy_s(char* dest, size_t dest_size, const char* source, size_t count) {
 namespace v8 {
 namespace internal {
 
+intptr_t OS::MaxVirtualMemory() {
+  return 0;
+}
+
+
 double ceiling(double x) {
   return ceil(x);
 }
@@ -733,6 +743,127 @@ void OS::StrNCpy(Vector<char> dest, const char* src, size_t n) {
 #undef STRUNCATE
 
 
+// Get the system's page size used by VirtualAlloc() or the next power
+// of two. The reason for always returning a power of two is that the
+// rounding up in OS::Allocate expects that.
+static size_t GetPageSize() {
+  static size_t page_size = 0;
+  if (page_size == 0) {
+    SYSTEM_INFO info;
+    GetSystemInfo(&info);
+    page_size = RoundUpToPowerOf2(info.dwPageSize);
+  }
+  return page_size;
+}
+
+
+// The allocation alignment is the guaranteed alignment for
+// VirtualAlloc'ed blocks of memory.
+size_t OS::AllocateAlignment() {
+  static size_t allocate_alignment = 0;
+  if (allocate_alignment == 0) {
+    SYSTEM_INFO info;
+    GetSystemInfo(&info);
+    allocate_alignment = info.dwAllocationGranularity;
+  }
+  return allocate_alignment;
+}
+
+
+void* OS::GetRandomMmapAddr() {
+  Isolate* isolate = Isolate::UncheckedCurrent();
+  // Note that the current isolate isn't set up in a call path via
+  // CpuFeatures::Probe. We don't care about randomization in this case because
+  // the code page is immediately freed.
+  if (isolate != NULL) {
+    // The address range used to randomize RWX allocations in OS::Allocate
+    // Try not to map pages into the default range that windows loads DLLs
+    // Use a multiple of 64k to prevent committing unused memory.
+    // Note: This does not guarantee RWX regions will be within the
+    // range kAllocationRandomAddressMin to kAllocationRandomAddressMax
+#ifdef V8_HOST_ARCH_64_BIT
+    static const intptr_t kAllocationRandomAddressMin = 0x0000000080000000;
+    static const intptr_t kAllocationRandomAddressMax = 0x000003FFFFFF0000;
+#else
+    static const intptr_t kAllocationRandomAddressMin = 0x04000000;
+    static const intptr_t kAllocationRandomAddressMax = 0x3FFF0000;
+#endif
+    uintptr_t address =
+        (isolate->random_number_generator()->NextInt() << kPageSizeBits) |
+        kAllocationRandomAddressMin;
+    address &= kAllocationRandomAddressMax;
+    return reinterpret_cast<void *>(address);
+  }
+  return NULL;
+}
+
+
+static void* RandomizedVirtualAlloc(size_t size, int action, int protection) {
+  LPVOID base = NULL;
+
+  if (protection == PAGE_EXECUTE_READWRITE || protection == PAGE_NOACCESS) {
+    // For exectutable pages try and randomize the allocation address
+    for (size_t attempts = 0; base == NULL && attempts < 3; ++attempts) {
+      base = VirtualAlloc(OS::GetRandomMmapAddr(), size, action, protection);
+    }
+  }
+
+  // After three attempts give up and let the OS find an address to use.
+  if (base == NULL) base = VirtualAlloc(NULL, size, action, protection);
+
+  return base;
+}
+
+
+void* OS::Allocate(const size_t requested,
+                   size_t* allocated,
+                   bool is_executable) {
+  // VirtualAlloc rounds allocated size to page size automatically.
+  size_t msize = RoundUp(requested, static_cast<int>(GetPageSize()));
+
+  // Windows XP SP2 allows Data Excution Prevention (DEP).
+  int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
+
+  LPVOID mbase = RandomizedVirtualAlloc(msize,
+                                        MEM_COMMIT | MEM_RESERVE,
+                                        prot);
+
+  if (mbase == NULL) {
+    LOG(Isolate::Current(), StringEvent("OS::Allocate", "VirtualAlloc failed"));
+    return NULL;
+  }
+
+  ASSERT(IsAligned(reinterpret_cast<size_t>(mbase), OS::AllocateAlignment()));
+
+  *allocated = msize;
+  return mbase;
+}
+
+
+void OS::Free(void* address, const size_t size) {
+  // TODO(1240712): VirtualFree has a return value which is ignored here.
+  VirtualFree(address, 0, MEM_RELEASE);
+  USE(size);
+}
+
+
+intptr_t OS::CommitPageSize() {
+  return 4096;
+}
+
+
+void OS::ProtectCode(void* address, const size_t size) {
+  DWORD old_protect;
+  VirtualProtect(address, size, PAGE_EXECUTE_READ, &old_protect);
+}
+
+
+void OS::Guard(void* address, const size_t size) {
+  DWORD oldprotect;
+  VirtualProtect(address, size, PAGE_NOACCESS, &oldprotect);
+}
+
+
 void OS::Sleep(int milliseconds) {
   ::Sleep(milliseconds);
 }
@@ -1237,6 +1368,111 @@ int OS::ActivationFrameAlignment() {
 }
 
 
+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* address = ReserveRegion(request_size);
+  if (address == NULL) return;
+  Address base = RoundUp(static_cast<Address>(address), alignment);
+  // Try reducing the size by freeing and then reallocating a specific area.
+  bool result = ReleaseRegion(address, request_size);
+  USE(result);
+  ASSERT(result);
+  address = VirtualAlloc(base, size, MEM_RESERVE, PAGE_NOACCESS);
+  if (address != NULL) {
+    request_size = size;
+    ASSERT(base == static_cast<Address>(address));
+  } else {
+    // Resizing failed, just go with a bigger area.
+    address = ReserveRegion(request_size);
+    if (address == NULL) return;
+  }
+  address_ = address;
+  size_ = request_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) {
+  ASSERT(IsReserved());
+  return UncommitRegion(address, size);
+}
+
+
+bool VirtualMemory::Guard(void* address) {
+  if (NULL == VirtualAlloc(address,
+                           OS::CommitPageSize(),
+                           MEM_COMMIT,
+                           PAGE_NOACCESS)) {
+    return false;
+  }
+  return true;
+}
+
+
+void* VirtualMemory::ReserveRegion(size_t size) {
+  return RandomizedVirtualAlloc(size, MEM_RESERVE, PAGE_NOACCESS);
+}
+
+
+bool VirtualMemory::CommitRegion(void* base, size_t size, bool is_executable) {
+  int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
+  if (NULL == VirtualAlloc(base, size, MEM_COMMIT, prot)) {
+    return false;
+  }
+  return true;
+}
+
+
+bool VirtualMemory::UncommitRegion(void* base, size_t size) {
+  return VirtualFree(base, size, MEM_DECOMMIT) != 0;
+}
+
+
+bool VirtualMemory::ReleaseRegion(void* base, size_t size) {
+  return VirtualFree(base, 0, MEM_RELEASE) != 0;
+}
+
+
+bool VirtualMemory::HasLazyCommits() {
+  // TODO(alph): implement for the platform.
+  return false;
+}
+
+
 // ----------------------------------------------------------------------------
 // Win32 thread support.