[compiler-rt] [NFC] Make RingBuffer an atomic pointer (PR #82547)

[Florian Mayer via llvm-commits]

================
@@ -1259,27 +1275,22 @@ class Allocator {
     storeEndMarker(RoundNewPtr, NewSize, BlockEnd);
   }
 
-  StackDepot *getDepotIfEnabled(const Options &Options) {
-    if (!UNLIKELY(Options.get(OptionBit::TrackAllocationStacks)))
-      return nullptr;
-    return Depot;
-  }
-
   void storePrimaryAllocationStackMaybe(const Options &Options, void *Ptr) {
-    auto *Depot = getDepotIfEnabled(Options);
-    if (!Depot)
+    auto *RingBuffer = getRingBufferIfEnabled(Options);
+    if (!RingBuffer)
       return;
     auto *Ptr32 = reinterpret_cast<u32 *>(Ptr);
-    Ptr32[MemTagAllocationTraceIndex] = collectStackTrace(Depot);
+    Ptr32[MemTagAllocationTraceIndex] = collectStackTrace(RingBuffer->Depot);
     Ptr32[MemTagAllocationTidIndex] = getThreadID();
   }
 
-  void storeRingBufferEntry(void *Ptr, u32 AllocationTrace, u32 AllocationTid,
+  void storeRingBufferEntry(AllocationRingBuffer *RB, void *Ptr,
----------------
fmayer wrote:

I suggest we change to

```
RingBuffer => RingBufferPtr
Var of AllocationRingBuffer => RB
RawRingBuffer => RBEntryAddress (and do the indexing in the same line)
```

I think "raw" is a bit confusing, especially as it meant something else before.

https://github.com/llvm/llvm-project/pull/82547