[sanitizer] Align & pad the allocator structures to the cacheline size v2

[cryptoad]

Summary

This is a new version of D44261, which broke some builds with older gcc, as
they can't align on a constexpr, but rather require an integer (see
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56859) among others.

We introduce SANITIZER_CACHE_LINE_SIZE in sanitizer_platform.h to be
used in ALIGNED attributes instead of using directly kCacheLineSize.

[cryptoad]

Couple of additional changes from the original patch.

lib/sanitizer_common/sanitizer_allocator_primary32.h

public:
 
   typedef SizeClassMap SizeClassMapT;
   static const uptr kNumClasses = SizeClassMap::kNumClasses;
 
  private:
   static const uptr kRegionSize = 1 << kRegionSizeLog;
   static const uptr kNumPossibleRegions = kSpaceSize / kRegionSize;
 
-  struct SizeClassInfo {
+  struct ALIGNED(SANITIZER_CACHE_LINE_SIZE) SizeClassInfo {
     SpinMutex mutex;
     IntrusiveList<TransferBatch> free_list;
     u32 rand_state;
-    char padding[kCacheLineSize - 2 * sizeof(uptr) -
-                 sizeof(IntrusiveList<TransferBatch>)];
   };
-  COMPILER_CHECK(sizeof(SizeClassInfo) == kCacheLineSize);
+  COMPILER_CHECK(sizeof(SizeClassInfo) % kCacheLineSize == 0);
 
   uptr ComputeRegionId(uptr mem) {
     const uptr res = mem >> kRegionSizeLog;
     CHECK_LT(res, kNumPossibleRegions);
     return res;
   }
 
   uptr ComputeRegionBeg(uptr mem) {

lib/sanitizer_common/sanitizer_allocator_primary64.h

if (kUsingConstantSpaceBeg) {
       CHECK_EQ(kSpaceBeg, address_range.Init(TotalSpaceSize, AllocatorName(),
                                              kSpaceBeg));
     } else {
       NonConstSpaceBeg = address_range.Init(TotalSpaceSize, AllocatorName());
       CHECK_NE(NonConstSpaceBeg, ~(uptr)0);
     }
     SetReleaseToOSIntervalMs(release_to_os_interval_ms);
     MapWithCallbackOrDie(SpaceEnd(), AdditionalSize());
+    // Check that the RegionInfo array is aligned on the CacheLine size.
+    DCHECK_EQ(SpaceEnd() & (kCacheLineSize - 1), 0);
   }
 
   s32 ReleaseToOSIntervalMs() const {
     return atomic_load(&release_to_os_interval_ms_, memory_order_relaxed);
   }
 
   void SetReleaseToOSIntervalMs(s32 release_to_os_interval_ms) {
     atomic_store(&release_to_os_interval_ms_, release_to_os_interval_ms,
private:
 
   struct ReleaseToOsInfo {
     uptr n_freed_at_last_release;
     uptr num_releases;
     u64 last_release_at_ns;
     u64 last_released_bytes;
   };
 
-  struct RegionInfo {
+  struct ALIGNED(SANITIZER_CACHE_LINE_SIZE) RegionInfo {
     BlockingMutex mutex;
     uptr num_freed_chunks;  // Number of elements in the freearray.
     uptr mapped_free_array;  // Bytes mapped for freearray.
     uptr allocated_user;  // Bytes allocated for user memory.
     uptr allocated_meta;  // Bytes allocated for metadata.
     uptr mapped_user;  // Bytes mapped for user memory.
     uptr mapped_meta;  // Bytes mapped for metadata.
     u32 rand_state;  // Seed for random shuffle, used if kRandomShuffleChunks.
     bool exhausted;  // Whether region is out of space for new chunks.
     Stats stats;
     ReleaseToOsInfo rtoi;
   };
-  COMPILER_CHECK(sizeof(RegionInfo) >= kCacheLineSize);
+  COMPILER_CHECK(sizeof(RegionInfo) % kCacheLineSize == 0);
 
   RegionInfo *GetRegionInfo(uptr class_id) const {
     CHECK_LT(class_id, kNumClasses);
     RegionInfo *regions =
         reinterpret_cast<RegionInfo *>(SpaceBeg() + kSpaceSize);
     return &regions[class_id];
   }
 

lib/sanitizer_common/sanitizer_common.h

 struct BufferedStackTrace;
 struct SignalContext;
 struct StackTrace;
 
 // Constants.
 const uptr kWordSize = SANITIZER_WORDSIZE / 8;
 const uptr kWordSizeInBits = 8 * kWordSize;
 
-#if defined(__powerpc__) || defined(__powerpc64__)
-  const uptr kCacheLineSize = 128;
-#else
-  const uptr kCacheLineSize = 64;
-#endif
+const uptr kCacheLineSize = SANITIZER_CACHE_LINE_SIZE;
+// Check that the CacheLine size is a power-of-two.
+COMPILER_CHECK((kCacheLineSize & (kCacheLineSize - 1)) == 0);
 
 const uptr kMaxPathLength = 4096;
 
 const uptr kMaxThreadStackSize = 1 << 30;  // 1Gb
 
 static const uptr kErrorMessageBufferSize = 1 << 16;
 
 // Denotes fake PC values that come from JIT/JAVA/etc.

lib/sanitizer_common/sanitizer_platform.h

 
 #if SANITIZER_FREEBSD || SANITIZER_MAC || SANITIZER_NETBSD || \
   SANITIZER_OPENBSD || SANITIZER_SOLARIS
 # define SANITIZER_MADVISE_DONTNEED MADV_FREE
 #else
 # define SANITIZER_MADVISE_DONTNEED MADV_DONTNEED
 #endif
 
+// Older gcc have issues aligning to a constexpr, and require an integer.
+// See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56859 among others.
+#if defined(__powerpc__) || defined(__powerpc64__)
+# define SANITIZER_CACHE_LINE_SIZE 128
+#else
+# define SANITIZER_CACHE_LINE_SIZE 64
+#endif
+
 #endif // SANITIZER_PLATFORM_H