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diff --git a/compiler-rt/lib/asan/asan_poisoning.cpp b/compiler-rt/lib/asan/asan_poisoning.cpp
new file mode 100644
index 000000000000..f3fbe684e2cb
--- /dev/null
+++ b/compiler-rt/lib/asan/asan_poisoning.cpp
@@ -0,0 +1,460 @@
+//===-- asan_poisoning.cpp ------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// Shadow memory poisoning by ASan RTL and by user application.
+//===----------------------------------------------------------------------===//
+
+#include "asan_poisoning.h"
+#include "asan_report.h"
+#include "asan_stack.h"
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_libc.h"
+#include "sanitizer_common/sanitizer_flags.h"
+
+namespace __asan {
+
+static atomic_uint8_t can_poison_memory;
+
+void SetCanPoisonMemory(bool value) {
+  atomic_store(&can_poison_memory, value, memory_order_release);
+}
+
+bool CanPoisonMemory() {
+  return atomic_load(&can_poison_memory, memory_order_acquire);
+}
+
+void PoisonShadow(uptr addr, uptr size, u8 value) {
+  if (value && !CanPoisonMemory()) return;
+  CHECK(AddrIsAlignedByGranularity(addr));
+  CHECK(AddrIsInMem(addr));
+  CHECK(AddrIsAlignedByGranularity(addr + size));
+  CHECK(AddrIsInMem(addr + size - SHADOW_GRANULARITY));
+  CHECK(REAL(memset));
+  FastPoisonShadow(addr, size, value);
+}
+
+void PoisonShadowPartialRightRedzone(uptr addr,
+                                     uptr size,
+                                     uptr redzone_size,
+                                     u8 value) {
+  if (!CanPoisonMemory()) return;
+  CHECK(AddrIsAlignedByGranularity(addr));
+  CHECK(AddrIsInMem(addr));
+  FastPoisonShadowPartialRightRedzone(addr, size, redzone_size, value);
+}
+
+struct ShadowSegmentEndpoint {
+  u8 *chunk;
+  s8 offset;  // in [0, SHADOW_GRANULARITY)
+  s8 value;  // = *chunk;
+
+  explicit ShadowSegmentEndpoint(uptr address) {
+    chunk = (u8*)MemToShadow(address);
+    offset = address & (SHADOW_GRANULARITY - 1);
+    value = *chunk;
+  }
+};
+
+void FlushUnneededASanShadowMemory(uptr p, uptr size) {
+  // Since asan's mapping is compacting, the shadow chunk may be
+  // not page-aligned, so we only flush the page-aligned portion.
+  ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
+}
+
+void AsanPoisonOrUnpoisonIntraObjectRedzone(uptr ptr, uptr size, bool poison) {
+  uptr end = ptr + size;
+  if (Verbosity()) {
+    Printf("__asan_%spoison_intra_object_redzone [%p,%p) %zd\n",
+           poison ? "" : "un", ptr, end, size);
+    if (Verbosity() >= 2)
+      PRINT_CURRENT_STACK();
+  }
+  CHECK(size);
+  CHECK_LE(size, 4096);
+  CHECK(IsAligned(end, SHADOW_GRANULARITY));
+  if (!IsAligned(ptr, SHADOW_GRANULARITY)) {
+    *(u8 *)MemToShadow(ptr) =
+        poison ? static_cast<u8>(ptr % SHADOW_GRANULARITY) : 0;
+    ptr |= SHADOW_GRANULARITY - 1;
+    ptr++;
+  }
+  for (; ptr < end; ptr += SHADOW_GRANULARITY)
+    *(u8*)MemToShadow(ptr) = poison ? kAsanIntraObjectRedzone : 0;
+}
+
+}  // namespace __asan
+
+// ---------------------- Interface ---------------- {{{1
+using namespace __asan;
+
+// Current implementation of __asan_(un)poison_memory_region doesn't check
+// that user program (un)poisons the memory it owns. It poisons memory
+// conservatively, and unpoisons progressively to make sure asan shadow
+// mapping invariant is preserved (see detailed mapping description here:
+// https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm).
+//
+// * if user asks to poison region [left, right), the program poisons
+// at least [left, AlignDown(right)).
+// * if user asks to unpoison region [left, right), the program unpoisons
+// at most [AlignDown(left), right).
+void __asan_poison_memory_region(void const volatile *addr, uptr size) {
+  if (!flags()->allow_user_poisoning || size == 0) return;
+  uptr beg_addr = (uptr)addr;
+  uptr end_addr = beg_addr + size;
+  VPrintf(3, "Trying to poison memory region [%p, %p)\n", (void *)beg_addr,
+          (void *)end_addr);
+  ShadowSegmentEndpoint beg(beg_addr);
+  ShadowSegmentEndpoint end(end_addr);
+  if (beg.chunk == end.chunk) {
+    CHECK_LT(beg.offset, end.offset);
+    s8 value = beg.value;
+    CHECK_EQ(value, end.value);
+    // We can only poison memory if the byte in end.offset is unaddressable.
+    // No need to re-poison memory if it is poisoned already.
+    if (value > 0 && value <= end.offset) {
+      if (beg.offset > 0) {
+        *beg.chunk = Min(value, beg.offset);
+      } else {
+        *beg.chunk = kAsanUserPoisonedMemoryMagic;
+      }
+    }
+    return;
+  }
+  CHECK_LT(beg.chunk, end.chunk);
+  if (beg.offset > 0) {
+    // Mark bytes from beg.offset as unaddressable.
+    if (beg.value == 0) {
+      *beg.chunk = beg.offset;
+    } else {
+      *beg.chunk = Min(beg.value, beg.offset);
+    }
+    beg.chunk++;
+  }
+  REAL(memset)(beg.chunk, kAsanUserPoisonedMemoryMagic, end.chunk - beg.chunk);
+  // Poison if byte in end.offset is unaddressable.
+  if (end.value > 0 && end.value <= end.offset) {
+    *end.chunk = kAsanUserPoisonedMemoryMagic;
+  }
+}
+
+void __asan_unpoison_memory_region(void const volatile *addr, uptr size) {
+  if (!flags()->allow_user_poisoning || size == 0) return;
+  uptr beg_addr = (uptr)addr;
+  uptr end_addr = beg_addr + size;
+  VPrintf(3, "Trying to unpoison memory region [%p, %p)\n", (void *)beg_addr,
+          (void *)end_addr);
+  ShadowSegmentEndpoint beg(beg_addr);
+  ShadowSegmentEndpoint end(end_addr);
+  if (beg.chunk == end.chunk) {
+    CHECK_LT(beg.offset, end.offset);
+    s8 value = beg.value;
+    CHECK_EQ(value, end.value);
+    // We unpoison memory bytes up to enbytes up to end.offset if it is not
+    // unpoisoned already.
+    if (value != 0) {
+      *beg.chunk = Max(value, end.offset);
+    }
+    return;
+  }
+  CHECK_LT(beg.chunk, end.chunk);
+  if (beg.offset > 0) {
+    *beg.chunk = 0;
+    beg.chunk++;
+  }
+  REAL(memset)(beg.chunk, 0, end.chunk - beg.chunk);
+  if (end.offset > 0 && end.value != 0) {
+    *end.chunk = Max(end.value, end.offset);
+  }
+}
+
+int __asan_address_is_poisoned(void const volatile *addr) {
+  return __asan::AddressIsPoisoned((uptr)addr);
+}
+
+uptr __asan_region_is_poisoned(uptr beg, uptr size) {
+  if (!size) return 0;
+  uptr end = beg + size;
+  if (SANITIZER_MYRIAD2) {
+    // On Myriad, address not in DRAM range need to be treated as
+    // unpoisoned.
+    if (!AddrIsInMem(beg) && !AddrIsInShadow(beg)) return 0;
+    if (!AddrIsInMem(end) && !AddrIsInShadow(end)) return 0;
+  } else {
+    if (!AddrIsInMem(beg)) return beg;
+    if (!AddrIsInMem(end)) return end;
+  }
+  CHECK_LT(beg, end);
+  uptr aligned_b = RoundUpTo(beg, SHADOW_GRANULARITY);
+  uptr aligned_e = RoundDownTo(end, SHADOW_GRANULARITY);
+  uptr shadow_beg = MemToShadow(aligned_b);
+  uptr shadow_end = MemToShadow(aligned_e);
+  // First check the first and the last application bytes,
+  // then check the SHADOW_GRANULARITY-aligned region by calling
+  // mem_is_zero on the corresponding shadow.
+  if (!__asan::AddressIsPoisoned(beg) &&
+      !__asan::AddressIsPoisoned(end - 1) &&
+      (shadow_end <= shadow_beg ||
+       __sanitizer::mem_is_zero((const char *)shadow_beg,
+                                shadow_end - shadow_beg)))
+    return 0;
+  // The fast check failed, so we have a poisoned byte somewhere.
+  // Find it slowly.
+  for (; beg < end; beg++)
+    if (__asan::AddressIsPoisoned(beg))
+      return beg;
+  UNREACHABLE("mem_is_zero returned false, but poisoned byte was not found");
+  return 0;
+}
+
+#define CHECK_SMALL_REGION(p, size, isWrite)                  \
+  do {                                                        \
+    uptr __p = reinterpret_cast<uptr>(p);                     \
+    uptr __size = size;                                       \
+    if (UNLIKELY(__asan::AddressIsPoisoned(__p) ||            \
+        __asan::AddressIsPoisoned(__p + __size - 1))) {       \
+      GET_CURRENT_PC_BP_SP;                                   \
+      uptr __bad = __asan_region_is_poisoned(__p, __size);    \
+      __asan_report_error(pc, bp, sp, __bad, isWrite, __size, 0);\
+    }                                                         \
+  } while (false)
+
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+u16 __sanitizer_unaligned_load16(const uu16 *p) {
+  CHECK_SMALL_REGION(p, sizeof(*p), false);
+  return *p;
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+u32 __sanitizer_unaligned_load32(const uu32 *p) {
+  CHECK_SMALL_REGION(p, sizeof(*p), false);
+  return *p;
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+u64 __sanitizer_unaligned_load64(const uu64 *p) {
+  CHECK_SMALL_REGION(p, sizeof(*p), false);
+  return *p;
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_unaligned_store16(uu16 *p, u16 x) {
+  CHECK_SMALL_REGION(p, sizeof(*p), true);
+  *p = x;
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_unaligned_store32(uu32 *p, u32 x) {
+  CHECK_SMALL_REGION(p, sizeof(*p), true);
+  *p = x;
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_unaligned_store64(uu64 *p, u64 x) {
+  CHECK_SMALL_REGION(p, sizeof(*p), true);
+  *p = x;
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+void __asan_poison_cxx_array_cookie(uptr p) {
+  if (SANITIZER_WORDSIZE != 64) return;
+  if (!flags()->poison_array_cookie) return;
+  uptr s = MEM_TO_SHADOW(p);
+  *reinterpret_cast<u8*>(s) = kAsanArrayCookieMagic;
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+uptr __asan_load_cxx_array_cookie(uptr *p) {
+  if (SANITIZER_WORDSIZE != 64) return *p;
+  if (!flags()->poison_array_cookie) return *p;
+  uptr s = MEM_TO_SHADOW(reinterpret_cast<uptr>(p));
+  u8 sval = *reinterpret_cast<u8*>(s);
+  if (sval == kAsanArrayCookieMagic) return *p;
+  // If sval is not kAsanArrayCookieMagic it can only be freed memory,
+  // which means that we are going to get double-free. So, return 0 to avoid
+  // infinite loop of destructors. We don't want to report a double-free here
+  // though, so print a warning just in case.
+  // CHECK_EQ(sval, kAsanHeapFreeMagic);
+  if (sval == kAsanHeapFreeMagic) {
+    Report("AddressSanitizer: loaded array cookie from free-d memory; "
+           "expect a double-free report\n");
+    return 0;
+  }
+  // The cookie may remain unpoisoned if e.g. it comes from a custom
+  // operator new defined inside a class.
+  return *p;
+}
+
+// This is a simplified version of __asan_(un)poison_memory_region, which
+// assumes that left border of region to be poisoned is properly aligned.
+static void PoisonAlignedStackMemory(uptr addr, uptr size, bool do_poison) {
+  if (size == 0) return;
+  uptr aligned_size = size & ~(SHADOW_GRANULARITY - 1);
+  PoisonShadow(addr, aligned_size,
+               do_poison ? kAsanStackUseAfterScopeMagic : 0);
+  if (size == aligned_size)
+    return;
+  s8 end_offset = (s8)(size - aligned_size);
+  s8* shadow_end = (s8*)MemToShadow(addr + aligned_size);
+  s8 end_value = *shadow_end;
+  if (do_poison) {
+    // If possible, mark all the bytes mapping to last shadow byte as
+    // unaddressable.
+    if (end_value > 0 && end_value <= end_offset)
+      *shadow_end = (s8)kAsanStackUseAfterScopeMagic;
+  } else {
+    // If necessary, mark few first bytes mapping to last shadow byte
+    // as addressable
+    if (end_value != 0)
+      *shadow_end = Max(end_value, end_offset);
+  }
+}
+
+void __asan_set_shadow_00(uptr addr, uptr size) {
+  REAL(memset)((void *)addr, 0, size);
+}
+
+void __asan_set_shadow_f1(uptr addr, uptr size) {
+  REAL(memset)((void *)addr, 0xf1, size);
+}
+
+void __asan_set_shadow_f2(uptr addr, uptr size) {
+  REAL(memset)((void *)addr, 0xf2, size);
+}
+
+void __asan_set_shadow_f3(uptr addr, uptr size) {
+  REAL(memset)((void *)addr, 0xf3, size);
+}
+
+void __asan_set_shadow_f5(uptr addr, uptr size) {
+  REAL(memset)((void *)addr, 0xf5, size);
+}
+
+void __asan_set_shadow_f8(uptr addr, uptr size) {
+  REAL(memset)((void *)addr, 0xf8, size);
+}
+
+void __asan_poison_stack_memory(uptr addr, uptr size) {
+  VReport(1, "poisoning: %p %zx\n", (void *)addr, size);
+  PoisonAlignedStackMemory(addr, size, true);
+}
+
+void __asan_unpoison_stack_memory(uptr addr, uptr size) {
+  VReport(1, "unpoisoning: %p %zx\n", (void *)addr, size);
+  PoisonAlignedStackMemory(addr, size, false);
+}
+
+void __sanitizer_annotate_contiguous_container(const void *beg_p,
+                                               const void *end_p,
+                                               const void *old_mid_p,
+                                               const void *new_mid_p) {
+  if (!flags()->detect_container_overflow) return;
+  VPrintf(2, "contiguous_container: %p %p %p %p\n", beg_p, end_p, old_mid_p,
+          new_mid_p);
+  uptr beg = reinterpret_cast<uptr>(beg_p);
+  uptr end = reinterpret_cast<uptr>(end_p);
+  uptr old_mid = reinterpret_cast<uptr>(old_mid_p);
+  uptr new_mid = reinterpret_cast<uptr>(new_mid_p);
+  uptr granularity = SHADOW_GRANULARITY;
+  if (!(beg <= old_mid && beg <= new_mid && old_mid <= end && new_mid <= end &&
+        IsAligned(beg, granularity))) {
+    GET_STACK_TRACE_FATAL_HERE;
+    ReportBadParamsToAnnotateContiguousContainer(beg, end, old_mid, new_mid,
+                                                 &stack);
+  }
+  CHECK_LE(end - beg,
+           FIRST_32_SECOND_64(1UL << 30, 1ULL << 34)); // Sanity check.
+
+  uptr a = RoundDownTo(Min(old_mid, new_mid), granularity);
+  uptr c = RoundUpTo(Max(old_mid, new_mid), granularity);
+  uptr d1 = RoundDownTo(old_mid, granularity);
+  // uptr d2 = RoundUpTo(old_mid, granularity);
+  // Currently we should be in this state:
+  // [a, d1) is good, [d2, c) is bad, [d1, d2) is partially good.
+  // Make a quick sanity check that we are indeed in this state.
+  //
+  // FIXME: Two of these three checks are disabled until we fix
+  // https://github.com/google/sanitizers/issues/258.
+  // if (d1 != d2)
+  //  CHECK_EQ(*(u8*)MemToShadow(d1), old_mid - d1);
+  if (a + granularity <= d1)
+    CHECK_EQ(*(u8*)MemToShadow(a), 0);
+  // if (d2 + granularity <= c && c <= end)
+  //   CHECK_EQ(*(u8 *)MemToShadow(c - granularity),
+  //            kAsanContiguousContainerOOBMagic);
+
+  uptr b1 = RoundDownTo(new_mid, granularity);
+  uptr b2 = RoundUpTo(new_mid, granularity);
+  // New state:
+  // [a, b1) is good, [b2, c) is bad, [b1, b2) is partially good.
+  PoisonShadow(a, b1 - a, 0);
+  PoisonShadow(b2, c - b2, kAsanContiguousContainerOOBMagic);
+  if (b1 != b2) {
+    CHECK_EQ(b2 - b1, granularity);
+    *(u8*)MemToShadow(b1) = static_cast<u8>(new_mid - b1);
+  }
+}
+
+const void *__sanitizer_contiguous_container_find_bad_address(
+    const void *beg_p, const void *mid_p, const void *end_p) {
+  if (!flags()->detect_container_overflow)
+    return nullptr;
+  uptr beg = reinterpret_cast<uptr>(beg_p);
+  uptr end = reinterpret_cast<uptr>(end_p);
+  uptr mid = reinterpret_cast<uptr>(mid_p);
+  CHECK_LE(beg, mid);
+  CHECK_LE(mid, end);
+  // Check some bytes starting from beg, some bytes around mid, and some bytes
+  // ending with end.
+  uptr kMaxRangeToCheck = 32;
+  uptr r1_beg = beg;
+  uptr r1_end = Min(beg + kMaxRangeToCheck, mid);
+  uptr r2_beg = Max(beg, mid - kMaxRangeToCheck);
+  uptr r2_end = Min(end, mid + kMaxRangeToCheck);
+  uptr r3_beg = Max(end - kMaxRangeToCheck, mid);
+  uptr r3_end = end;
+  for (uptr i = r1_beg; i < r1_end; i++)
+    if (AddressIsPoisoned(i))
+      return reinterpret_cast<const void *>(i);
+  for (uptr i = r2_beg; i < mid; i++)
+    if (AddressIsPoisoned(i))
+      return reinterpret_cast<const void *>(i);
+  for (uptr i = mid; i < r2_end; i++)
+    if (!AddressIsPoisoned(i))
+      return reinterpret_cast<const void *>(i);
+  for (uptr i = r3_beg; i < r3_end; i++)
+    if (!AddressIsPoisoned(i))
+      return reinterpret_cast<const void *>(i);
+  return nullptr;
+}
+
+int __sanitizer_verify_contiguous_container(const void *beg_p,
+                                            const void *mid_p,
+                                            const void *end_p) {
+  return __sanitizer_contiguous_container_find_bad_address(beg_p, mid_p,
+                                                           end_p) == nullptr;
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+void __asan_poison_intra_object_redzone(uptr ptr, uptr size) {
+  AsanPoisonOrUnpoisonIntraObjectRedzone(ptr, size, true);
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+void __asan_unpoison_intra_object_redzone(uptr ptr, uptr size) {
+  AsanPoisonOrUnpoisonIntraObjectRedzone(ptr, size, false);
+}
+
+// --- Implementation of LSan-specific functions --- {{{1
+namespace __lsan {
+bool WordIsPoisoned(uptr addr) {
+  return (__asan_region_is_poisoned(addr, sizeof(uptr)) != 0);
+}
+}