[libc-commits] [libc] [libc] Implement dual freestore rotation for baremetal heap (PR #209811)

[Daniel Thornburgh via libc-commits]

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@@ -68,15 +83,79 @@ class FreeListHeap {
 
   bool is_valid_ptr(const void *ptr) const { return ptr >= begin && ptr < end; }
 
+  /// The store that allocations are served from.
+  LIBC_INLINE FreeStore &active_free_store() { return free_stores[active]; }
+
+  /// @returns The index of the store that receives newly freed blocks. With a
+  /// single free store this is the active store itself, so freed memory is
+  /// immediately available again.
+  LIBC_INLINE size_t quarantine_store_index() const {
+    return (active + 1) % NUM_FREE_STORES;
+  }
+
+  /// @returns Whether `neighbor`, a free block adjacent to a block owned by
+  /// `store_index`, can be merged into it.
+  LIBC_INLINE static bool can_merge(BlockRef neighbor, size_t store_index) {
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mysterymath wrote:

This logic feels like it belongs on block; maybe transferring a block to another free store index coalesces? Unsure. It does feel like having the coalescing logic in the heap is oddly high-level.

https://github.com/llvm/llvm-project/pull/209811