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authorGravatar Abseil Team <absl-team@google.com>2023-02-06 15:23:40 -0800
committerGravatar Copybara-Service <copybara-worker@google.com>2023-02-06 15:24:24 -0800
commit92fc445f7c0d8158c5f26abab9049fcfbcd0ccff (patch)
tree950b231ee5b9c973269a9de775ca45b8e0183e9a
parentcdad8cd96ee9bfe11056997dc960eb2e52c6b00e (diff)
Fix a discrepancy between absl::Hash and absl::HashOf for some negative signed integral types and improve the performance of absl::Hash.
PiperOrigin-RevId: 507598042 Change-Id: I96a7bd6b9c360f435f216b2671ae84d9768a46e8
-rw-r--r--absl/hash/hash_test.cc15
-rw-r--r--absl/hash/internal/hash.h3
2 files changed, 15 insertions, 3 deletions
diff --git a/absl/hash/hash_test.cc b/absl/hash/hash_test.cc
index 5b556180..4ed6e50a 100644
--- a/absl/hash/hash_test.cc
+++ b/absl/hash/hash_test.cc
@@ -17,6 +17,7 @@
#include <algorithm>
#include <array>
#include <bitset>
+#include <cstdint>
#include <cstring>
#include <deque>
#include <forward_list>
@@ -1241,14 +1242,24 @@ TEST(HashTest, DoesNotUseImplicitConversionsToBool) {
TEST(HashOf, MatchesHashForSingleArgument) {
std::string s = "forty two";
- int i = 42;
double d = 42.0;
std::tuple<int, int> t{4, 2};
+ int i = 42;
+ int neg_i = -42;
+ int16_t i16 = 42;
+ int16_t neg_i16 = -42;
+ int8_t i8 = 42;
+ int8_t neg_i8 = -42;
EXPECT_EQ(absl::HashOf(s), absl::Hash<std::string>{}(s));
- EXPECT_EQ(absl::HashOf(i), absl::Hash<int>{}(i));
EXPECT_EQ(absl::HashOf(d), absl::Hash<double>{}(d));
EXPECT_EQ(absl::HashOf(t), (absl::Hash<std::tuple<int, int>>{}(t)));
+ EXPECT_EQ(absl::HashOf(i), absl::Hash<int>{}(i));
+ EXPECT_EQ(absl::HashOf(neg_i), absl::Hash<int>{}(neg_i));
+ EXPECT_EQ(absl::HashOf(i16), absl::Hash<int16_t>{}(i16));
+ EXPECT_EQ(absl::HashOf(neg_i16), absl::Hash<int16_t>{}(neg_i16));
+ EXPECT_EQ(absl::HashOf(i8), absl::Hash<int8_t>{}(i8));
+ EXPECT_EQ(absl::HashOf(neg_i8), absl::Hash<int8_t>{}(neg_i8));
}
TEST(HashOf, MatchesHashOfTupleForMultipleArguments) {
diff --git a/absl/hash/internal/hash.h b/absl/hash/internal/hash.h
index ccf4cc1a..eb50e2c7 100644
--- a/absl/hash/internal/hash.h
+++ b/absl/hash/internal/hash.h
@@ -969,7 +969,8 @@ class ABSL_DLL MixingHashState : public HashStateBase<MixingHashState> {
// The result should be the same as running the whole algorithm, but faster.
template <typename T, absl::enable_if_t<IntegralFastPath<T>::value, int> = 0>
static size_t hash(T value) {
- return static_cast<size_t>(Mix(Seed(), static_cast<uint64_t>(value)));
+ return static_cast<size_t>(
+ Mix(Seed(), static_cast<std::make_unsigned_t<T>>(value)));
}
// Overload of MixingHashState::hash()