[NFC][Asan] Set AP32::kMetadataSize to 0

Asan does not use metadata with primary allocators.
It should match AP64::kMetadataSize whic is 0.

Depends on D86917.

Reviewed By: morehouse

Differential Revision: https://reviews.llvm.org/D86919

compiler-rt/lib/asan/asan_allocator.h

@@ -171,7 +171,7 @@ template <typename AddressSpaceViewTy>
 struct AP32 {
   static const uptr kSpaceBeg = 0;
   static const u64 kSpaceSize = SANITIZER_MMAP_RANGE_SIZE;
-  static const uptr kMetadataSize = 16;
+  static const uptr kMetadataSize = 0;
   typedef __asan::SizeClassMap SizeClassMap;
   static const uptr kRegionSizeLog = 20;
   using AddressSpaceView = AddressSpaceViewTy;

compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary32.h

@@ -153,6 +153,7 @@ class SizeClassAllocator32 {
   }
 
   void *GetMetaData(const void *p) {
+    CHECK(kMetadataSize);
     CHECK(PointerIsMine(p));
     uptr mem = reinterpret_cast<uptr>(p);
     uptr beg = ComputeRegionBeg(mem);

compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary64.h

@@ -230,6 +230,7 @@ class SizeClassAllocator64 {
   static uptr ClassID(uptr size) { return SizeClassMap::ClassID(size); }
 
   void *GetMetaData(const void *p) {
+    CHECK(kMetadataSize);
     uptr class_id = GetSizeClass(p);
     uptr size = ClassIdToSize(class_id);
     uptr chunk_idx = GetChunkIdx(reinterpret_cast<uptr>(p), size);