[scudo] Pass the max number of blocks to popBlocks (#70243)

Make the cache have the fully control on how many blocks to be popped
(At before, it depended the number of blocks stored in the
TransferBatch)

Author: ChiaHungDuan

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

@@ -40,7 +40,11 @@ template <class SizeClassAllocator> struct SizeClassAllocatorLocalCache {
     DCHECK_LT(ClassId, NumClasses);
     PerClass *C = &PerClassArray[ClassId];
     if (C->Count == 0) {
-      if (UNLIKELY(!refill(C, ClassId)))
+      initCacheMaybe(C);
+
+      // Refill half of the number of max cached.
+      DCHECK_GT(C->MaxCount / 2, 0U);
+      if (UNLIKELY(!refill(C, ClassId, C->MaxCount / 2)))
         return nullptr;
       DCHECK_GT(C->Count, 0);
     }
@@ -173,14 +177,10 @@ template <class SizeClassAllocator> struct SizeClassAllocatorLocalCache {
       deallocate(BatchClassId, B);
   }
 
-  NOINLINE bool refill(PerClass *C, uptr ClassId) {
-    initCacheMaybe(C);
-
-    // TODO(chiahungduan): Pass the max number cached for each size class.
+  NOINLINE bool refill(PerClass *C, uptr ClassId, u16 MaxRefill) {
     const u16 NumBlocksRefilled =
-        Allocator->popBlocks(this, ClassId, C->Chunks);
-    DCHECK_LE(NumBlocksRefilled,
-              getMaxCached(SizeClassAllocator::getSizeByClassId(ClassId)));
+        Allocator->popBlocks(this, ClassId, C->Chunks, MaxRefill);
+    DCHECK_LE(NumBlocksRefilled, MaxRefill);
     C->Count = static_cast<u16>(C->Count + NumBlocksRefilled);
     return NumBlocksRefilled != 0;
   }

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

@@ -191,7 +191,11 @@ template <typename Config> class SizeClassAllocator32 {
     return BlockSize > PageSize;
   }
 
-  u16 popBlocks(CacheT *C, uptr ClassId, CompactPtrT *ToArray) {
+  // Note that the `MaxBlockCount` will be used when we support arbitrary blocks
+  // count. Now it's the same as the number of blocks stored in the
+  // `TransferBatch`.
+  u16 popBlocks(CacheT *C, uptr ClassId, CompactPtrT *ToArray,
+                UNUSED const u16 MaxBlockCount) {
     TransferBatchT *B = popBatch(C, ClassId);
     if (!B)
       return 0;

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

@@ -221,7 +221,11 @@ template <typename Config> class SizeClassAllocator64 {
     DCHECK_EQ(BlocksInUse, BatchClassUsedInFreeLists);
   }
 
-  u16 popBlocks(CacheT *C, uptr ClassId, CompactPtrT *ToArray) {
+  // Note that the `MaxBlockCount` will be used when we support arbitrary blocks
+  // count. Now it's the same as the number of blocks stored in the
+  // `TransferBatch`.
+  u16 popBlocks(CacheT *C, uptr ClassId, CompactPtrT *ToArray,
+                UNUSED const u16 MaxBlockCount) {
     TransferBatchT *B = popBatch(C, ClassId);
     if (!B)
       return 0;