ART: Improve bit-test function
Improve the test for single-bit-set by using POPCOUNT. Saves about
.1% of instructions.
Bug: 78568168
Test: m test-art-host
Change-Id: Ifaa5987f1ca9e7507ac6c57dac7da5fae6dcef8d
diff --git a/libdexfile/dex/dex_file_verifier.cc b/libdexfile/dex/dex_file_verifier.cc
index 73be166..5f7b4e8 100644
--- a/libdexfile/dex/dex_file_verifier.cc
+++ b/libdexfile/dex/dex_file_verifier.cc
@@ -3015,11 +3015,14 @@
}
// Fields and methods may have only one of public/protected/private.
-static bool CheckAtMostOneOfPublicProtectedPrivate(uint32_t flags) {
- size_t count = (((flags & kAccPublic) == 0) ? 0 : 1) +
- (((flags & kAccProtected) == 0) ? 0 : 1) +
- (((flags & kAccPrivate) == 0) ? 0 : 1);
- return count <= 1;
+ALWAYS_INLINE
+static constexpr bool CheckAtMostOneOfPublicProtectedPrivate(uint32_t flags) {
+ // Semantically we want 'return POPCOUNT(flags & kAcc) <= 1;'.
+ static_assert(IsPowerOfTwo(0), "0 not marked as power of two");
+ static_assert(IsPowerOfTwo(kAccPublic), "kAccPublic not marked as power of two");
+ static_assert(IsPowerOfTwo(kAccProtected), "kAccProtected not marked as power of two");
+ static_assert(IsPowerOfTwo(kAccPrivate), "kAccPrivate not marked as power of two");
+ return IsPowerOfTwo(flags & (kAccPublic | kAccProtected | kAccPrivate));
}
// Helper functions to retrieve names from the dex file. We do not want to rely on DexFile