[sanitizer] factor out ByteMap from SizeClassAllocator32 so that it can be later replaced with a more memory-efficient implementation on 64-bit.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@182234 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 39 insertions, 18 deletions

diff --git a/lib/sanitizer_common/sanitizer_allocator.h b/lib/sanitizer_common/sanitizer_allocator.h
index 0472edf2..0542addb 100644
--- a/lib/sanitizer_common/sanitizer_allocator.h
+++ b/lib/sanitizer_common/sanitizer_allocator.h
@@ -561,6 +561,30 @@ class SizeClassAllocator64 {
   }
 };
 
+// Maps integers in rage [0, kSize) to u8 values.
+template<u64 kSize>
+class FlatByteMap {
+ public:
+  void TestOnlyInit() {
+    internal_memset(map_, 0, sizeof(map_));
+  }
+
+  void set(uptr idx, u8 val) {
+    CHECK_LT(idx, kSize);
+    CHECK_EQ(0U, map_[idx]);
+    map_[idx] = val;
+  }
+  u8 operator[] (uptr idx) {
+    CHECK_LT(idx, kSize);
+    // FIXME: CHECK may be too expensive here.
+    return map_[idx];
+  }
+ private:
+  u8 map_[kSize];
+};
+
+// FIXME: Also implement TwoLevelByteMap.
+
 // SizeClassAllocator32 -- allocator for 32-bit address space.
 // This allocator can theoretically be used on 64-bit arch, but there it is less
 // efficient than SizeClassAllocator64.
@@ -572,7 +596,7 @@ class SizeClassAllocator64 {
 //   a result of a single call to MmapAlignedOrDie(kRegionSize, kRegionSize).
 // Since the regions are aligned by kRegionSize, there are exactly
 // kNumPossibleRegions possible regions in the address space and so we keep
-// an u8 array possible_regions[kNumPossibleRegions] to store the size classes.
+// a ByteMap possible_regions to store the size classes of each Region.
 // 0 size class means the region is not used by the allocator.
 //
 // One Region is used to allocate chunks of a single size class.
@@ -583,16 +607,19 @@ class SizeClassAllocator64 {
 // chache-line aligned.
 template <const uptr kSpaceBeg, const u64 kSpaceSize,
           const uptr kMetadataSize, class SizeClassMap,
+          const uptr kRegionSizeLog,
+          class ByteMap,
           class MapUnmapCallback = NoOpMapUnmapCallback>
 class SizeClassAllocator32 {
  public:
   typedef typename SizeClassMap::TransferBatch Batch;
   typedef SizeClassAllocator32<kSpaceBeg, kSpaceSize, kMetadataSize,
-      SizeClassMap, MapUnmapCallback> ThisT;
+      SizeClassMap, kRegionSizeLog, ByteMap, MapUnmapCallback> ThisT;
   typedef SizeClassAllocatorLocalCache<ThisT> AllocatorCache;
 
   void Init() {
-    state_ = reinterpret_cast<State *>(MapWithCallback(sizeof(State)));
+    possible_regions.TestOnlyInit();
+    internal_memset(size_class_info_array, 0, sizeof(size_class_info_array));
   }
 
   void *MapWithCallback(uptr size) {
@@ -649,7 +676,7 @@ class SizeClassAllocator32 {
   }
 
   uptr GetSizeClass(void *p) {
-    return state_->possible_regions[ComputeRegionId(reinterpret_cast<uptr>(p))];
+    return possible_regions[ComputeRegionId(reinterpret_cast<uptr>(p))];
   }
 
   void *GetBlockBegin(void *p) {
@@ -674,16 +701,15 @@ class SizeClassAllocator32 {
     // No need to lock here.
     uptr res = 0;
     for (uptr i = 0; i < kNumPossibleRegions; i++)
-      if (state_->possible_regions[i])
+      if (possible_regions[i])
         res += kRegionSize;
     return res;
   }
 
   void TestOnlyUnmap() {
     for (uptr i = 0; i < kNumPossibleRegions; i++)
-      if (state_->possible_regions[i])
+      if (possible_regions[i])
         UnmapWithCallback((i * kRegionSize), kRegionSize);
-    UnmapWithCallback(reinterpret_cast<uptr>(state_), sizeof(State));
   }
 
   // ForceLock() and ForceUnlock() are needed to implement Darwin malloc zone
@@ -706,8 +732,8 @@ class SizeClassAllocator32 {
   template<typename Callable>
   void ForEachChunk(const Callable &callback) {
     for (uptr region = 0; region < kNumPossibleRegions; region++)
-      if (state_->possible_regions[region]) {
-        uptr chunk_size = SizeClassMap::Size(state_->possible_regions[region]);
+      if (possible_regions[region]) {
+        uptr chunk_size = SizeClassMap::Size(possible_regions[region]);
         uptr max_chunks_in_region = kRegionSize / (chunk_size + kMetadataSize);
         uptr region_beg = region * kRegionSize;
         for (uptr p = region_beg;
@@ -726,7 +752,6 @@ class SizeClassAllocator32 {
   static const uptr kNumClasses = SizeClassMap::kNumClasses;
 
  private:
-  static const uptr kRegionSizeLog = SANITIZER_WORDSIZE == 64 ? 24 : 20;
   static const uptr kRegionSize = 1 << kRegionSizeLog;
   static const uptr kNumPossibleRegions = kSpaceSize / kRegionSize;
 
@@ -754,14 +779,13 @@ class SizeClassAllocator32 {
     MapUnmapCallback().OnMap(res, kRegionSize);
     stat->Add(AllocatorStatMmapped, kRegionSize);
     CHECK_EQ(0U, (res & (kRegionSize - 1)));
-    CHECK_EQ(0U, state_->possible_regions[ComputeRegionId(res)]);
-    state_->possible_regions[ComputeRegionId(res)] = class_id;
+    possible_regions.set(ComputeRegionId(res), class_id);
     return res;
   }
 
   SizeClassInfo *GetSizeClassInfo(uptr class_id) {
     CHECK_LT(class_id, kNumClasses);
-    return &state_->size_class_info_array[class_id];
+    return &size_class_info_array[class_id];
   }
 
   void PopulateFreeList(AllocatorStats *stat, AllocatorCache *c,
@@ -792,11 +816,8 @@ class SizeClassAllocator32 {
     }
   }
 
-  struct State {
-    u8 possible_regions[kNumPossibleRegions];
-    SizeClassInfo size_class_info_array[kNumClasses];
-  };
-  State *state_;
+  ByteMap possible_regions;
+  SizeClassInfo size_class_info_array[kNumClasses];
 };
 
 // Objects of this type should be used as local caches for SizeClassAllocator64