[PATCH] D122518: [scudo] Use template specialization on Quarantine to avoid zero-length array

[Dominic Chen via Phabricator via llvm-commits]

ddcc updated this revision to Diff 418758.
ddcc added a comment.

Move definitions out of class


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D122518/new/

https://reviews.llvm.org/D122518

Files:
  compiler-rt/lib/scudo/standalone/secondary.h


Index: compiler-rt/lib/scudo/standalone/secondary.h
===================================================================
--- compiler-rt/lib/scudo/standalone/secondary.h
+++ compiler-rt/lib/scudo/standalone/secondary.h
@@ -113,6 +113,28 @@
   }
 }
 
+struct CachedBlock {
+  uptr CommitBase;
+  uptr CommitSize;
+  uptr MapBase;
+  uptr MapSize;
+  uptr BlockBegin;
+  [[no_unique_address]] MapPlatformData Data;
+  u64 Time;
+};
+
+// Template specialization to avoid producing zero-length array
+template <size_t Size> class QuarantineBlocks {
+public:
+  CachedBlock &operator[](uptr Idx) { return Blocks[Idx]; }
+private:
+  CachedBlock Blocks[Size];
+};
+template <> class QuarantineBlocks<0> {
+public:
+  CachedBlock &operator[](uptr UNUSED Idx) { UNREACHABLE("Unsupported!"); }
+};
+
 template <typename Config> class MapAllocatorCache {
 public:
   // Ensure the default maximum specified fits the array.
@@ -352,16 +374,6 @@
             &MapInfo[I].Data);
   }
 
-  struct CachedBlock {
-    uptr CommitBase;
-    uptr CommitSize;
-    uptr MapBase;
-    uptr MapSize;
-    uptr BlockBegin;
-    [[no_unique_address]] MapPlatformData Data;
-    u64 Time;
-  };
-
   void releaseIfOlderThan(CachedBlock &Entry, u64 Time) {
     if (!Entry.CommitBase || !Entry.Time)
       return;
@@ -395,7 +407,7 @@
   atomic_s32 ReleaseToOsIntervalMs = {};
 
   CachedBlock Entries[Config::SecondaryCacheEntriesArraySize] = {};
-  CachedBlock Quarantine[Config::SecondaryCacheQuarantineSize] = {};
+  QuarantineBlocks<Config::SecondaryCacheQuarantineSize> Quarantine = {};
 };
 
 template <typename Config> class MapAllocator {


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