Make more allocator methods work correctly with in an out-of-process mode.

[delcypher]

Summary

This makes GetBlockBegin() and GetBlockBeginFastLocked() work correctly with RemoteAddressSpaceView.

This has a knock on effect of also making the PointerIsMine() and
GetMetaData() methods behave correctly when RemoteAddressSpaceView
is used to instantiate the allocators.

This will be used by future out-of-process allocator enumeration
patches.

rdar://problem/45284065

[delcypher]

@vitalybuka In https://reviews.llvm.org/D57279 it looks like you're looking at performing a refactor. Could we land this first? I realise this is addressing my patch series out-of-order but this patches doesn't actually depend on the prior two patches (https://reviews.llvm.org/D56207 and https://reviews.llvm.org/D56206) in the review series.

[delcypher]

@vitalybuka Thanks.

compiler-rt/trunk/lib/sanitizer_common/sanitizer_allocator_primary64.h

void *GetBlockBegin(const void *p) {
     uptr class_id = GetSizeClass(p);
     uptr size = ClassIdToSize(class_id);
     if (!size) return nullptr;
     uptr chunk_idx = GetChunkIdx((uptr)p, size);
     uptr reg_beg = GetRegionBegin(p);
     uptr beg = chunk_idx * size;
     uptr next_beg = beg + size;
     if (class_id >= kNumClasses) return nullptr;
-    RegionInfo *region = GetRegionInfo(class_id);
+    const RegionInfo *region = AddressSpaceView::Load(GetRegionInfo(class_id));
     if (region->mapped_user >= next_beg)
       return reinterpret_cast<void*>(reg_beg + beg);
     return nullptr;
   }
 
   uptr GetActuallyAllocatedSize(void *p) {
     CHECK(PointerIsMine(p));
     return ClassIdToSize(GetSizeClass(p));

compiler-rt/trunk/lib/sanitizer_common/sanitizer_allocator_secondary.h

void *GetMetaData(const void *p) {
     }
     return GetHeader(p) + 1;
   }
 
   void *GetBlockBegin(const void *ptr) {
     uptr p = reinterpret_cast<uptr>(ptr);
     SpinMutexLock l(&mutex_);
     uptr nearest_chunk = 0;
+    Header *const *chunks = AddressSpaceView::Load(chunks_, n_chunks_);
     // Cache-friendly linear search.
     for (uptr i = 0; i < n_chunks_; i++) {
-      uptr ch = reinterpret_cast<uptr>(chunks_[i]);
+      uptr ch = reinterpret_cast<uptr>(chunks[i]);
       if (p < ch) continue;  // p is at left to this chunk, skip it.
       if (p - ch < p - nearest_chunk)
         nearest_chunk = ch;
     }
     if (!nearest_chunk)
       return nullptr;
-    Header *h = reinterpret_cast<Header *>(nearest_chunk);
+    const Header *h =
+        AddressSpaceView::Load(reinterpret_cast<Header *>(nearest_chunk));
+    Header *h_ptr = reinterpret_cast<Header *>(nearest_chunk);
     CHECK_GE(nearest_chunk, h->map_beg);
     CHECK_LT(nearest_chunk, h->map_beg + h->map_size);
     CHECK_LE(nearest_chunk, p);
     if (h->map_beg + h->map_size <= p)
       return nullptr;
-    return GetUser(h);
+    return GetUser(h_ptr);
   }
 
   void EnsureSortedChunks() {
     if (chunks_sorted_) return;
     Header **chunks = AddressSpaceView::LoadWritable(chunks_, n_chunks_);
     Sort(reinterpret_cast<uptr *>(chunks), n_chunks_);
     for (uptr i = 0; i < n_chunks_; i++)
       AddressSpaceView::LoadWritable(chunks[i])->chunk_idx = i;
     chunks_sorted_ = true;
   }
 
   // This function does the same as GetBlockBegin, but is much faster.
   // Must be called with the allocator locked.
   void *GetBlockBeginFastLocked(void *ptr) {
     mutex_.CheckLocked();
     uptr p = reinterpret_cast<uptr>(ptr);
     uptr n = n_chunks_;
     if (!n) return nullptr;
     EnsureSortedChunks();
-    auto min_mmap_ = reinterpret_cast<uptr>(chunks_[0]);
-    auto max_mmap_ =
-        reinterpret_cast<uptr>(chunks_[n - 1]) + chunks_[n - 1]->map_size;
+    Header *const *chunks = AddressSpaceView::Load(chunks_, n_chunks_);
+    auto min_mmap_ = reinterpret_cast<uptr>(chunks[0]);
+    auto max_mmap_ = reinterpret_cast<uptr>(chunks[n - 1]) +
+                     AddressSpaceView::Load(chunks[n - 1])->map_size;
     if (p < min_mmap_ || p >= max_mmap_)
       return nullptr;
     uptr beg = 0, end = n - 1;
     // This loop is a log(n) lower_bound. It does not check for the exact match
     // to avoid expensive cache-thrashing loads.
     while (end - beg >= 2) {
       uptr mid = (beg + end) / 2;  // Invariant: mid >= beg + 1
-      if (p < reinterpret_cast<uptr>(chunks_[mid]))
-        end = mid - 1;  // We are not interested in chunks_[mid].
+      if (p < reinterpret_cast<uptr>(chunks[mid]))
+        end = mid - 1;  // We are not interested in chunks[mid].
       else
-        beg = mid;  // chunks_[mid] may still be what we want.
+        beg = mid;  // chunks[mid] may still be what we want.
     }
 
     if (beg < end) {
       CHECK_EQ(beg + 1, end);
       // There are 2 chunks left, choose one.
-      if (p >= reinterpret_cast<uptr>(chunks_[end]))
+      if (p >= reinterpret_cast<uptr>(chunks[end]))
         beg = end;
     }
 
-    Header *h = chunks_[beg];
+    const Header *h = AddressSpaceView::Load(chunks[beg]);
+    Header *h_ptr = chunks[beg];
     if (h->map_beg + h->map_size <= p || p < h->map_beg)
       return nullptr;
-    return GetUser(h);
+    return GetUser(h_ptr);
   }
 
   void PrintStats() {
     Printf("Stats: LargeMmapAllocator: allocated %zd times, "
            "remains %zd (%zd K) max %zd M; by size logs: ",
            stats.n_allocs, stats.n_allocs - stats.n_frees,
            stats.currently_allocated >> 10, stats.max_allocated >> 20);
     for (uptr i = 0; i < ARRAY_SIZE(stats.by_size_log); i++) {