[compiler-rt] [scudo] Add EnableMultiRegions mode (PR #98076)

[via llvm-commits]

================
@@ -56,6 +56,17 @@ template <typename Config> class SizeClassAllocator64 {
   static_assert(RegionSizeLog >= GroupSizeLog,
                 "Group size shouldn't be greater than the region size");
   static const uptr GroupScale = GroupSizeLog - CompactPtrScale;
+  // Local cache stores the pointers in the type of compacted pointer and the
+  // compaction is done by calculating the offset to the base address of a
+  // region. Currently, we don't support decompacting through multiple regions
+  // because of the concern of performance and so we disable the pointer
+  // compaction.
+  // TODO(chiahungduan): Allow local cache store the raw pointer and keep
+  // storing the compacted pointers in each region to save memory.
+  static const bool DisablePtrCompaction = Config::getEnableMultiRegions();
+  static_assert(!DisablePtrCompaction || sizeof(CompactPtrT) == sizeof(uptr),
+                "Pointer compaction is disabled, `CompactPtrT` needs to be the "
+                "same size of `uptr`");
----------------
ChiaHungDuan wrote:

Done

https://github.com/llvm/llvm-project/pull/98076