[sanitizer] NFC: add static_assert to confirm that we use optimal ByteMap type

[vitalybuka]

Summary

If bots work we can replace #ifs with template specialization by TwoLevelByteMapSize1.

[eugenis]

LGTM

[phosek]

This seems to be failing on our Mac bots with this error:

FAILED: compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonNoHooks.ios.dir/sanitizer_allocator.cc.o 
/b/s/w/ir/k/recipe_cleanup/clangK3gGtn/llvm_build_dir/./bin/clang++ --target=x86_64-apple-darwin17.7.0  -DHAVE_RPC_XDR_H=0 -D_DEBUG -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/.. -stdlib=libc++ -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -std=c++11 -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fdiagnostics-color -Wall -std=c++11 -Wno-unused-parameter -O2 -g  -arch armv7 -arch armv7s -arch arm64   -UNDEBUG  -stdlib=libc++ -miphoneos-version-min=8.0 -isysroot /b/s/w/ir/cache/macos_sdk/XCode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS12.1.sdk -fPIC -fno-builtin -fno-exceptions -funwind-tables -fno-stack-protector -fno-sanitize=safe-stack -fvisibility=hidden -fno-lto -O3 -gline-tables-only -Wno-gnu -Wno-variadic-macros -Wno-c99-extensions -Wno-non-virtual-dtor -fno-rtti -Wframe-larger-than=570 -Wglobal-constructors -DSANITIZER_SUPPORTS_WEAK_HOOKS=0 -MD -MT compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonNoHooks.ios.dir/sanitizer_allocator.cc.o -MF compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonNoHooks.ios.dir/sanitizer_allocator.cc.o.d -o compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonNoHooks.ios.dir/sanitizer_allocator.cc.o -c /b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc
In file included from /b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc:14:
In file included from /b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator.h:74:
/b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary32.h:69:3: error: static_assert failed due to requirement 'TwoLevelByteMapSize1 > 128' "TwoLevelByteMap should be used"
  static_assert(TwoLevelByteMapSize1 > 128, "TwoLevelByteMap should be used");
  ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~
/b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator_combined.h:29:34: note: in instantiation of template class '__sanitizer::SizeClassAllocator32<__sanitizer::AP32>' requested here
                        typename PrimaryAllocator::AddressSpaceView>::value,
                                 ^
/b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc:87:52: note: in instantiation of template class '__sanitizer::CombinedAllocator<__sanitizer::SizeClassAllocator32<__sanitizer::AP32>, __sanitizer::SizeClassAllocatorLocalCache<__sanitizer::SizeClassAllocator32<__sanitizer::AP32> >, __sanitizer::LargeMmapAllocator<__sanitizer::NoOpMapUnmapCallback, __sanitizer::LargeMmapAllocatorPtrArrayStatic, __sanitizer::LocalAddressSpaceView>, __sanitizer::LocalAddressSpaceView>' requested here
static ALIGNED(64) char internal_alloc_placeholder[sizeof(InternalAllocator)];
                                                   ^
In file included from /b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc:14:
In file included from /b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator.h:75:
/b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator_local_cache.h:21:27: error: no type named 'AllocatorCache' in '__sanitizer::SizeClassAllocator32<__sanitizer::AP32>'
    : SizeClassAllocator::AllocatorCache {};
      ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
/b/s/w/ir/k/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc:91:31: note: in instantiation of template class '__sanitizer::SizeClassAllocatorLocalCache<__sanitizer::SizeClassAllocator32<__sanitizer::AP32> >' requested here
static InternalAllocatorCache internal_allocator_cache;
                              ^
2 errors generated.

[jfb]

Reverted in r359352.

[vitalybuka]

reduce threshold to fix mac and android

[vitalybuka]

format

compiler-rt/trunk/lib/sanitizer_common/sanitizer_allocator_primary32.h

 struct SizeClassAllocator32FlagMasks {  //  Bit masks.
   enum {
     kRandomShuffleChunks = 1,
     kUseSeparateSizeClassForBatch = 2,
     kForTest = 4,
   };
 };
 
+// This template is not necessary but t helps to see values if static_assert
+// fails.
+// FIXME: Replace check with automatic type detection. D61206
+template <bool Expected, u64 MinSize, u64 ActualSize>
+struct CheckTwoLevelByteMapSize {
+  static_assert((ActualSize >= MinSize) == Expected,
+                "Unexpected ByteMap type for the size");
+};
+
 template <class Params>
 class SizeClassAllocator32 {
+ private:
+  static const u64 TwoLevelByteMapSize1 =
+      (Params::kSpaceSize >> Params::kRegionSizeLog) >> 12;
+  static const u64 kMinFirstMapSizeTwoLevelByteMap = 4;
+
  public:
   using AddressSpaceView = typename Params::AddressSpaceView;
   static const uptr kSpaceBeg = Params::kSpaceBeg;
   static const u64 kSpaceSize = Params::kSpaceSize;
   static const uptr kMetadataSize = Params::kMetadataSize;
   typedef typename Params::SizeClassMap SizeClassMap;
   static const uptr kRegionSizeLog = Params::kRegionSizeLog;
   typedef typename Params::ByteMap ByteMap;
   typedef typename Params::MapUnmapCallback MapUnmapCallback;
 
 #if SANITIZER_WORDSIZE == 32
+  CheckTwoLevelByteMapSize<false, kMinFirstMapSizeTwoLevelByteMap,
+                           TwoLevelByteMapSize1>
+      Check;
   using BM = FlatByteMap<(Params::kSpaceSize >> Params::kRegionSizeLog),
                          AddressSpaceView>;
 #elif SANITIZER_WORDSIZE == 64
-  using BM =
-      TwoLevelByteMap<((Params::kSpaceSize >> Params::kRegionSizeLog) >> 12),
-                      1 << 12, AddressSpaceView>;
+  CheckTwoLevelByteMapSize<true, kMinFirstMapSizeTwoLevelByteMap,
+                           TwoLevelByteMapSize1>
+      Check;
+  using BM = TwoLevelByteMap<TwoLevelByteMapSize1, 1 << 12, AddressSpaceView>;
 #endif
   static_assert((Params::kFlags & SizeClassAllocator32FlagMasks::kForTest) ||
                     is_same<BM, ByteMap>::value,
                 "Unexpected ByteMap type");
 
   static_assert(
 
       is_same<typename ByteMap::AddressSpaceView, AddressSpaceView>::value,