--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/compiler-rt/lib/gwp_asan/common.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,100 @@
+//===-- common.cpp ----------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "gwp_asan/common.h"
+#include "gwp_asan/stack_trace_compressor.h"
+
+#include <assert.h>
+
+using AllocationMetadata = gwp_asan::AllocationMetadata;
+using Error = gwp_asan::Error;
+
+namespace gwp_asan {
+
+const char *ErrorToString(const Error &E) {
+  switch (E) {
+  case Error::UNKNOWN:
+    return "Unknown";
+  case Error::USE_AFTER_FREE:
+    return "Use After Free";
+  case Error::DOUBLE_FREE:
+    return "Double Free";
+  case Error::INVALID_FREE:
+    return "Invalid (Wild) Free";
+  case Error::BUFFER_OVERFLOW:
+    return "Buffer Overflow";
+  case Error::BUFFER_UNDERFLOW:
+    return "Buffer Underflow";
+  }
+  __builtin_trap();
+}
+
+void AllocationMetadata::RecordAllocation(uintptr_t AllocAddr,
+                                          size_t AllocSize) {
+  Addr = AllocAddr;
+  Size = AllocSize;
+  IsDeallocated = false;
+
+  AllocationTrace.ThreadID = getThreadID();
+  DeallocationTrace.TraceSize = 0;
+  DeallocationTrace.ThreadID = kInvalidThreadID;
+}
+
+void AllocationMetadata::RecordDeallocation() {
+  IsDeallocated = true;
+  DeallocationTrace.ThreadID = getThreadID();
+}
+
+void AllocationMetadata::CallSiteInfo::RecordBacktrace(
+    options::Backtrace_t Backtrace) {
+  TraceSize = 0;
+  if (!Backtrace)
+    return;
+
+  uintptr_t UncompressedBuffer[kMaxTraceLengthToCollect];
+  size_t BacktraceLength =
+      Backtrace(UncompressedBuffer, kMaxTraceLengthToCollect);
+  TraceSize =
+      compression::pack(UncompressedBuffer, BacktraceLength, CompressedTrace,
+                        AllocationMetadata::kStackFrameStorageBytes);
+}
+
+size_t AllocatorState::maximumAllocationSize() const { return PageSize; }
+
+uintptr_t AllocatorState::slotToAddr(size_t N) const {
+  return GuardedPagePool + (PageSize * (1 + N)) + (maximumAllocationSize() * N);
+}
+
+bool AllocatorState::isGuardPage(uintptr_t Ptr) const {
+  assert(pointerIsMine(reinterpret_cast<void *>(Ptr)));
+  size_t PageOffsetFromPoolStart = (Ptr - GuardedPagePool) / PageSize;
+  size_t PagesPerSlot = maximumAllocationSize() / PageSize;
+  return (PageOffsetFromPoolStart % (PagesPerSlot + 1)) == 0;
+}
+
+static size_t addrToSlot(const AllocatorState *State, uintptr_t Ptr) {
+  size_t ByteOffsetFromPoolStart = Ptr - State->GuardedPagePool;
+  return ByteOffsetFromPoolStart /
+         (State->maximumAllocationSize() + State->PageSize);
+}
+
+size_t AllocatorState::getNearestSlot(uintptr_t Ptr) const {
+  if (Ptr <= GuardedPagePool + PageSize)
+    return 0;
+  if (Ptr > GuardedPagePoolEnd - PageSize)
+    return MaxSimultaneousAllocations - 1;
+
+  if (!isGuardPage(Ptr))
+    return addrToSlot(this, Ptr);
+
+  if (Ptr % PageSize <= PageSize / 2)
+    return addrToSlot(this, Ptr - PageSize); // Round down.
+  return addrToSlot(this, Ptr + PageSize);   // Round up.
+}
+
+} // namespace gwp_asan