Index: lib/sanitizer_common/sanitizer_allocator_primary32.h
===================================================================
--- lib/sanitizer_common/sanitizer_allocator_primary32.h
+++ lib/sanitizer_common/sanitizer_allocator_primary32.h
@@ -266,14 +266,12 @@
   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;
Index: lib/sanitizer_common/sanitizer_allocator_primary64.h
===================================================================
--- lib/sanitizer_common/sanitizer_allocator_primary64.h
+++ lib/sanitizer_common/sanitizer_allocator_primary64.h
@@ -80,6 +80,8 @@
     }
     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 {
@@ -584,7 +586,7 @@
     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.
@@ -597,7 +599,7 @@
     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);
Index: lib/sanitizer_common/sanitizer_common.h
===================================================================
--- lib/sanitizer_common/sanitizer_common.h
+++ lib/sanitizer_common/sanitizer_common.h
@@ -39,11 +39,9 @@
 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;
 
Index: lib/sanitizer_common/sanitizer_platform.h
===================================================================
--- lib/sanitizer_common/sanitizer_platform.h
+++ lib/sanitizer_common/sanitizer_platform.h
@@ -309,4 +309,12 @@
 # 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