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[NFC][sanitizer] Use power of two in TwoLevelMap 

Using divisions by non power of two makes
a difference on x86_64 and aarch64 benchmarks.
This commit is contained in:
Vitaly Buka 2021-10-24 17:34:13 -07:00
parent 384ec7dc8c
commit 8cd51a69e5
1 changed files with 9 additions and 5 deletions
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14
compiler-rt/lib/sanitizer_common/sanitizer_flat_map.h
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@ -65,6 +65,10 @@ template <typename T, u64 kSize1, u64 kSize2,
typename AddressSpaceViewTy = LocalAddressSpaceView,
class MapUnmapCallback = NoOpMapUnmapCallback>
class TwoLevelMap {
static_assert(IsPowerOfTwo(kSize2), "");
static constexpr uptr kSize2Shift = Log2(kSize2);
static constexpr uptr kSize2Mask = kSize2 - 1;
public:
using AddressSpaceView = AddressSpaceViewTy;
void Init() {
@ -100,19 +104,19 @@ class TwoLevelMap {
bool contains(uptr idx) const {
CHECK_LT(idx, kSize1 * kSize2);
return Get(idx / kSize2);
return Get(idx >> kSize2Shift);
}
const T &operator[](uptr idx) const {
DCHECK_LT(idx, kSize1 * kSize2);
T *map2 = GetOrCreate(idx / kSize2);
return *AddressSpaceView::Load(&map2[idx % kSize2]);
T *map2 = GetOrCreate(idx >> kSize2Shift);
return *AddressSpaceView::Load(&map2[idx & kSize2Mask]);
}
T &operator[](uptr idx) {
DCHECK_LT(idx, kSize1 * kSize2);
T *map2 = GetOrCreate(idx / kSize2);
return *AddressSpaceView::LoadWritable(&map2[idx % kSize2]);
T *map2 = GetOrCreate(idx >> kSize2Shift);
return *AddressSpaceView::LoadWritable(&map2[idx & kSize2Mask]);
}
private: