[scudo] Skip visiting all free blocks if grouping is disabled

[Chia-hungDuan]

Summary

This is only applied to SizeClassAllocator64 which has single region.
In SizeClassAllocator32, the region size has to be equal to the group
size.

[Chia-hungDuan]

Fix literal type used by GroupSizeLog

[cferris]

Small comment nit.

compiler-rt/lib/scudo/standalone/primary64.h

54

be greater

[Chia-hungDuan]

Address review comment

[cferris]

LGTM.

compiler-rt/lib/scudo/standalone/primary32.h

NOINLINE uptr releaseToOSMaybe(SizeClassInfo *Sci, uptr ClassId,
 
     const uptr First = Sci->MinRegionIndex;
     const uptr Last = Sci->MaxRegionIndex;
     DCHECK_NE(Last, 0U);
     DCHECK_LE(First, Last);
     uptr TotalReleasedBytes = 0;
     const uptr Base = First * RegionSize;
     const uptr NumberOfRegions = Last - First + 1U;
-    const uptr GroupSize = (1U << GroupSizeLog);
+    const uptr GroupSize = (1UL << GroupSizeLog);
     const uptr CurGroupBase =
         compactPtrGroupBase(compactPtr(ClassId, Sci->CurrentRegion));
 
     ReleaseRecorder Recorder(Base);
     PageReleaseContext Context(BlockSize, NumberOfRegions,
                                /*ReleaseSize=*/RegionSize);
 
     auto DecompactPtr = [](CompactPtrT CompactPtr) {

compiler-rt/lib/scudo/standalone/primary64.h

 // The memory used by this allocator is never unmapped, but can be partially
 // released if the platform allows for it.
 
 template <typename Config> class SizeClassAllocator64 {
 public:
   typedef typename Config::Primary::CompactPtrT CompactPtrT;
   typedef typename Config::Primary::SizeClassMap SizeClassMap;
   static const uptr CompactPtrScale = Config::Primary::CompactPtrScale;
+  static const uptr RegionSizeLog = Config::Primary::RegionSizeLog;
   static const uptr GroupSizeLog = Config::Primary::GroupSizeLog;
+  static_assert(RegionSizeLog >= GroupSizeLog,
+                "Group size shouldn't be greater than the region size");
   static const uptr GroupScale = GroupSizeLog - CompactPtrScale;
   typedef SizeClassAllocator64<Config> ThisT;
   typedef SizeClassAllocatorLocalCache<ThisT> CacheT;
   typedef typename CacheT::TransferBatch TransferBatch;
   typedef typename CacheT::BatchGroup BatchGroup;
 
   static uptr getSizeByClassId(uptr ClassId) {
     return (ClassId == SizeClassMap::BatchClassId)
                ? roundUp(sizeof(TransferBatch), 1U << CompactPtrScale)
                : SizeClassMap::getSizeByClassId(ClassId);
   }
 
   static bool canAllocate(uptr Size) { return Size <= SizeClassMap::MaxSize; }
 
   void init(s32 ReleaseToOsInterval) NO_THREAD_SAFETY_ANALYSIS {
     DCHECK(isAligned(reinterpret_cast<uptr>(this), alignof(ThisT)));
 
     const uptr PageSize = getPageSizeCached();
-    const uptr GroupSize = (1U << GroupSizeLog);
+    const uptr GroupSize = (1UL << GroupSizeLog);
     const uptr PagesInGroup = GroupSize / PageSize;
     const uptr MinSizeClass = getSizeByClassId(1);
     // When trying to release pages back to memory, visiting smaller size
     // classes is expensive. Therefore, we only try to release smaller size
     // classes when the amount of free blocks goes over a certain threshold (See
     // the comment in releaseToOSMaybe() for more details). For example, for
     // size class 32, we only do the release when the size of free blocks is
     // greater than 97% of pages in a group. However, this may introduce another
void init(s32 ReleaseToOsInterval) NO_THREAD_SAFETY_ANALYSIS {
     const u64 Time = getMonotonicTimeFast();
     if (!getRandom(reinterpret_cast<void *>(&Seed), sizeof(Seed)))
       Seed = static_cast<u32>(Time ^ (PrimaryBase >> 12));
 
     for (uptr I = 0; I < NumClasses; I++) {
       RegionInfo *Region = getRegionInfo(I);
       // The actual start of a region is offset by a random number of pages
       // when PrimaryEnableRandomOffset is set.
-      Region->RegionBeg =
-          (PrimaryBase + (I << Config::Primary::RegionSizeLog)) +
+      Region->RegionBeg = (PrimaryBase + (I << RegionSizeLog)) +
                           (Config::Primary::EnableRandomOffset
                                ? ((getRandomModN(&Seed, 16) + 1) * PageSize)
                                : 0);
       Region->RandState = getRandomU32(&Seed);
       // Releasing small blocks is expensive, set a higher threshold to avoid
       // frequent page releases.
       if (isSmallBlock(getSizeByClassId(I)))
         Region->TryReleaseThreshold = PageSize * SmallerBlockReleasePageDelta;
       else
         Region->TryReleaseThreshold = PageSize;
       Region->ReleaseInfo.LastReleaseAtNs = Time;
 
       Region->MemMapInfo.MemMap = ReservedMemory.dispatch(
-          PrimaryBase + (I << Config::Primary::RegionSizeLog), RegionSize);
+          PrimaryBase + (I << RegionSizeLog), RegionSize);
       CHECK(Region->MemMapInfo.MemMap.isAllocated());
     }
     shuffle(RegionInfoArray, NumClasses, &Seed);
 
     setOption(Option::ReleaseInterval, static_cast<sptr>(ReleaseToOsInterval));
   }
 
   void unmapTestOnly() NO_THREAD_SAFETY_ANALYSIS {
if (ClassId == SizeClassMap::BatchClassId) {
       ScopedLock L(Region->FLLock);
       pushBatchClassBlocks(Region, Array, Size);
       return;
     }
 
     // TODO(chiahungduan): Consider not doing grouping if the group size is not
     // greater than the block size with a certain scale.
 
-    // Sort the blocks so that blocks belonging to the same group can be pushed
-    // together.
     bool SameGroup = true;
+    if (GroupSizeLog < RegionSizeLog) {
+      // Sort the blocks so that blocks belonging to the same group can be
+      // pushed together.
       for (u32 I = 1; I < Size; ++I) {
         if (compactPtrGroup(Array[I - 1]) != compactPtrGroup(Array[I]))
           SameGroup = false;
         CompactPtrT Cur = Array[I];
         u32 J = I;
         while (J > 0 && compactPtrGroup(Cur) < compactPtrGroup(Array[J - 1])) {
           Array[J] = Array[J - 1];
           --J;
         }
         Array[J] = Cur;
       }
+    }
 
     {
       ScopedLock L(Region->FLLock);
       pushBlocksImpl(C, ClassId, Region, Array, Size, SameGroup);
     }
   }
 
   void disable() NO_THREAD_SAFETY_ANALYSIS {
if (MinDistance <= 8192) {
         B.BlockBegin -= B.BlockSize;
     }
     return B;
   }
 
   AtomicOptions Options;
 
 private:
-  static const uptr RegionSize = 1UL << Config::Primary::RegionSizeLog;
+  static const uptr RegionSize = 1UL << RegionSizeLog;
   static const uptr NumClasses = SizeClassMap::NumClasses;
   static const uptr PrimarySize = RegionSize * NumClasses;
 
   static const uptr MapSizeIncrement = Config::Primary::MapSizeIncrement;
   // Fill at most this number of batches from the newly map'd memory.
   static const u32 MaxNumBatches = SCUDO_ANDROID ? 4U : 8U;
 
   struct ReleaseToOsInfo {
bool hasChanceToReleasePages(RegionInfo *Region, uptr BlockSize,
 
     return true;
   }
 
   SinglyLinkedList<BatchGroup>
   collectGroupsToRelease(RegionInfo *Region, const uptr BlockSize,
                          const uptr AllocatedUserEnd, const uptr CompactPtrBase)
       REQUIRES(Region->MMLock, Region->FLLock) {
-    const uptr GroupSize = (1U << GroupSizeLog);
+    const uptr GroupSize = (1UL << GroupSizeLog);
     const uptr PageSize = getPageSizeCached();
     SinglyLinkedList<BatchGroup> GroupsToRelease;
 
     // We are examining each group and will take the minimum distance to the
     // release threshold as the next Region::TryReleaseThreshold(). Note that if
     // the size of free blocks has reached the release threshold, the distance
     // to the next release will be PageSize * SmallerBlockReleasePageDelta. See
     // the comment on `SmallerBlockReleasePageDelta` for more details.
collectGroupsToRelease(RegionInfo *Region, const uptr BlockSize,
     return GroupsToRelease;
   }
 
   PageReleaseContext
   markFreeBlocks(RegionInfo *Region, const uptr BlockSize,
                  const uptr AllocatedUserEnd, const uptr CompactPtrBase,
                  SinglyLinkedList<BatchGroup> &GroupsToRelease)
       REQUIRES(Region->MMLock) EXCLUDES(Region->FLLock) {
-    const uptr GroupSize = (1U << GroupSizeLog);
+    const uptr GroupSize = (1UL << GroupSizeLog);
     auto DecompactPtr = [CompactPtrBase](CompactPtrT CompactPtr) {
       return decompactPtrInternal(CompactPtrBase, CompactPtr);
     };
 
     const uptr ReleaseBase = decompactGroupBase(
         CompactPtrBase, GroupsToRelease.front()->CompactPtrGroupBase);
     const uptr LastGroupEnd =
         Min(decompactGroupBase(CompactPtrBase,