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authorGravatar Abseil Team <absl-team@google.com>2019-10-23 19:35:39 -0700
committerGravatar Derek Mauro <dmauro@google.com>2019-10-24 10:29:13 -0400
commit078b89b3c046d230ef3ad39494e5852184eb528b (patch)
tree90368e0b398c3e43196c823504b88ab78a8408b3 /absl
parent19b021cb3ff23048dfbe236a4e611925d8930831 (diff)
Export of internal Abseil changes
-- e54b9c7bbb0c58475676c268e2e19c69f4bce48a by Jorg Brown <jorg@google.com>: Tweak ABSL_PREDICT_TRUE slightly, for better code on some platforms and/or optimization levels. "false || (x)" is more verbose than "!!(x)", but ultimately more efficient. For example, given this code: void InitIfNecessary() { if (ABSL_PREDICT_TRUE(NeedsInit())) { SlowInitIfNecessary(); } } Clang with default optimization level will produce: Before this CL After this CL InitIfNecessary: InitIfNecessary: push rbp push rbp mov rbp, rsp mov rbp, rsp call NeedsInit call NeedsInit xor al, -1 xor al, -1 test al, 1 test al, 1 jne .LBB2_1 jne .LBB3_1 jmp .LBB2_2 jmp .LBB3_2 .LBB2_1: .LBB3_1: call SlowInitIfNecessary call SlowInitIfNecessary .LBB2_2: .LBB3_2: pop rbp pop rbp ret ret PiperOrigin-RevId: 276401386 -- 0a3c4dfd8342bf2b1b11a87f1c662c883f73cab7 by Abseil Team <absl-team@google.com>: Fix comment nit: sem_open => sem_init. The code calls sem_init, not sem_open, to initialize an unnamed semaphore. (sem_open creates or opens a named semaphore.) PiperOrigin-RevId: 276344072 -- b36a664e9459057509a90e83d3482e1d3a4c44c7 by Abseil Team <absl-team@google.com>: Fix typo in flat_hash_map.h: exchaged -> exchanged PiperOrigin-RevId: 276295792 -- 7bbd8d18276eb110c8335743e35fceb662ddf3d6 by Samuel Benzaquen <sbenza@google.com>: Add assertions to verify use of iterators. PiperOrigin-RevId: 276283300 -- 677398a8ffcb1f59182cffe57a4fe7ff147a0404 by Laramie Leavitt <lar@google.com>: Migrate distribution_impl.h/cc to generate_real.h/cc. Combine the methods RandU64To<Float,Double> into a single method: GenerateRealFromBits(). Remove rejection sampling from absl::uniform_real_distribution. PiperOrigin-RevId: 276158675 -- c60c9d11d24b0c546329d998e78e15a84b3153f5 by Abseil Team <absl-team@google.com>: Internal change PiperOrigin-RevId: 276126962 -- 4c840cab6a8d86efa29b397cafaf7520eece68cc by Andy Soffer <asoffer@google.com>: Update CMakeLists.txt to address https://github.com/abseil/abseil-cpp/issues/365. This does not cover every platform, but it does at least address the first-order issue of assuming gcc implies x86. PiperOrigin-RevId: 276116253 -- 98da366e6b5d51afe5d7ac6722126aca23d85ee6 by Abseil Team <absl-team@google.com>: Internal change PiperOrigin-RevId: 276097452 GitOrigin-RevId: e54b9c7bbb0c58475676c268e2e19c69f4bce48a Change-Id: I02d84454bb71ab21ad3d39650acf6cc6e36f58d7
Diffstat (limited to 'absl')
-rw-r--r--absl/base/BUILD.bazel25
-rw-r--r--absl/base/CMakeLists.txt26
-rw-r--r--absl/base/config.h2
-rw-r--r--absl/base/internal/exponential_biased.cc84
-rw-r--r--absl/base/internal/exponential_biased.h77
-rw-r--r--absl/base/internal/exponential_biased_test.cc168
-rw-r--r--absl/base/optimization.h2
-rw-r--r--absl/container/BUILD.bazel1
-rw-r--r--absl/container/CMakeLists.txt1
-rw-r--r--absl/container/flat_hash_map.h2
-rw-r--r--absl/container/internal/hashtablez_sampler.cc83
-rw-r--r--absl/container/internal/raw_hash_set.h20
-rw-r--r--absl/container/internal/raw_hash_set_test.cc2
-rw-r--r--absl/copts/AbseilConfigureCopts.cmake25
-rw-r--r--absl/random/BUILD.bazel2
-rw-r--r--absl/random/CMakeLists.txt17
-rw-r--r--absl/random/beta_distribution.h31
-rw-r--r--absl/random/beta_distribution_test.cc2
-rw-r--r--absl/random/exponential_distribution.h14
-rw-r--r--absl/random/gaussian_distribution.h22
-rw-r--r--absl/random/internal/BUILD.bazel16
-rw-r--r--absl/random/internal/distribution_impl.h194
-rw-r--r--absl/random/internal/generate_real.h144
-rw-r--r--absl/random/internal/generate_real_test.cc (renamed from absl/random/internal/distribution_impl_test.cc)111
-rw-r--r--absl/random/log_uniform_int_distribution.h2
-rw-r--r--absl/random/poisson_distribution.h20
-rw-r--r--absl/random/uniform_int_distribution.h1
-rw-r--r--absl/random/uniform_real_distribution.h15
28 files changed, 739 insertions, 370 deletions
diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index d74bac6..ffeca63 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -558,6 +558,31 @@ cc_test(
)
cc_library(
+ name = "exponential_biased",
+ srcs = ["internal/exponential_biased.cc"],
+ hdrs = ["internal/exponential_biased.h"],
+ linkopts = ABSL_DEFAULT_LINKOPTS,
+ visibility = [
+ "//absl:__subpackages__",
+ ],
+ deps = [":core_headers"],
+)
+
+cc_test(
+ name = "exponential_biased_test",
+ size = "small",
+ srcs = ["internal/exponential_biased_test.cc"],
+ copts = ABSL_TEST_COPTS,
+ linkopts = ABSL_DEFAULT_LINKOPTS,
+ visibility = ["//visibility:private"],
+ deps = [
+ ":exponential_biased",
+ "//absl/strings",
+ "@com_google_googletest//:gtest_main",
+ ],
+)
+
+cc_library(
name = "scoped_set_env",
testonly = 1,
srcs = ["internal/scoped_set_env.cc"],
diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt
index 79ee5b9..2698213 100644
--- a/absl/base/CMakeLists.txt
+++ b/absl/base/CMakeLists.txt
@@ -505,6 +505,32 @@ absl_cc_test(
absl_cc_library(
NAME
+ exponential_biased
+ SRCS
+ "internal/exponential_biased.cc"
+ HDRS
+ "internal/exponential_biased.h"
+ COPTS
+ ${ABSL_DEFAULT_COPTS}
+ DEPS
+ absl::core_headers
+)
+
+absl_cc_test(
+ NAME
+ exponential_biased_test
+ SRCS
+ "internal/exponential_biased_test.cc"
+ COPTS
+ ${ABSL_TEST_COPTS}
+ DEPS
+ absl::exponential_biased
+ absl::strings
+ gmock_main
+)
+
+absl_cc_library(
+ NAME
scoped_set_env
SRCS
"internal/scoped_set_env.cc"
diff --git a/absl/base/config.h b/absl/base/config.h
index 039b73d..24851fa 100644
--- a/absl/base/config.h
+++ b/absl/base/config.h
@@ -307,7 +307,7 @@
// ABSL_HAVE_SEMAPHORE_H
//
-// Checks whether the platform supports the <semaphore.h> header and sem_open(3)
+// Checks whether the platform supports the <semaphore.h> header and sem_init(3)
// family of functions as standardized in POSIX.1-2001.
//
// Note: While Apple provides <semaphore.h> for both iOS and macOS, it is
diff --git a/absl/base/internal/exponential_biased.cc b/absl/base/internal/exponential_biased.cc
new file mode 100644
index 0000000..d7ffd18
--- /dev/null
+++ b/absl/base/internal/exponential_biased.cc
@@ -0,0 +1,84 @@
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/base/internal/exponential_biased.h"
+
+#include <stdint.h>
+
+#include <atomic>
+#include <cmath>
+#include <limits>
+
+#include "absl/base/attributes.h"
+#include "absl/base/optimization.h"
+
+namespace absl {
+namespace base_internal {
+
+// The algorithm generates a random number between 0 and 1 and applies the
+// inverse cumulative distribution function for an exponential. Specifically:
+// Let m be the inverse of the sample period, then the probability
+// distribution function is m*exp(-mx) so the CDF is
+// p = 1 - exp(-mx), so
+// q = 1 - p = exp(-mx)
+// log_e(q) = -mx
+// -log_e(q)/m = x
+// log_2(q) * (-log_e(2) * 1/m) = x
+// In the code, q is actually in the range 1 to 2**26, hence the -26 below
+int64_t ExponentialBiased::Get(int64_t mean) {
+ if (ABSL_PREDICT_FALSE(!initialized_)) {
+ Initialize();
+ }
+
+ uint64_t rng = NextRandom(rng_);
+ rng_ = rng;
+
+ // Take the top 26 bits as the random number
+ // (This plus the 1<<58 sampling bound give a max possible step of
+ // 5194297183973780480 bytes.)
+ // The uint32_t cast is to prevent a (hard-to-reproduce) NAN
+ // under piii debug for some binaries.
+ double q = static_cast<uint32_t>(rng >> (kPrngNumBits - 26)) + 1.0;
+ // Put the computed p-value through the CDF of a geometric.
+ double interval = (std::log2(q) - 26) * (-std::log(2.0) * mean);
+ // Very large values of interval overflow int64_t. To avoid that, we will cheat
+ // and clamp any huge values to (int64_t max)/2. This is a potential source of
+ // bias, but the mean would need to be such a large value that it's not likely
+ // to come up. For example, with a mean of 1e18, the probability of hitting
+ // this condition is about 1/1000. For a mean of 1e17, standard calculators
+ // claim that this event won't happen.
+ if (interval > static_cast<double>(std::numeric_limits<int64_t>::max() / 2)) {
+ return std::numeric_limits<int64_t>::max() / 2;
+ }
+
+ return static_cast<int64_t>(interval);
+}
+
+void ExponentialBiased::Initialize() {
+ // We don't get well distributed numbers from `this` so we call NextRandom() a
+ // bunch to mush the bits around. We use a global_rand to handle the case
+ // where the same thread (by memory address) gets created and destroyed
+ // repeatedly.
+ ABSL_CONST_INIT static std::atomic<uint32_t> global_rand(0);
+ uint64_t r = reinterpret_cast<uint64_t>(this) +
+ global_rand.fetch_add(1, std::memory_order_relaxed);
+ for (int i = 0; i < 20; ++i) {
+ r = NextRandom(r);
+ }
+ rng_ = r;
+ initialized_ = true;
+}
+
+} // namespace base_internal
+} // namespace absl
diff --git a/absl/base/internal/exponential_biased.h b/absl/base/internal/exponential_biased.h
new file mode 100644
index 0000000..cac2d8a
--- /dev/null
+++ b/absl/base/internal/exponential_biased.h
@@ -0,0 +1,77 @@
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_BASE_INTERNAL_EXPONENTIAL_BIASED_H_
+#define ABSL_BASE_INTERNAL_EXPONENTIAL_BIASED_H_
+
+#include <stdint.h>
+
+namespace absl {
+namespace base_internal {
+
+// ExponentialBiased provides a small and fast random number generator for a
+// rounded exponential distribution. This generator doesn't requires very little
+// state doesn't impose synchronization overhead, which makes it useful in some
+// specialized scenarios.
+//
+// For the generated variable X, X ~ floor(Exponential(1/mean)). The floor
+// operation introduces a small amount of bias, but the distribution is useful
+// to generate a wait time. That is, if an operation is supposed to happen on
+// average to 1/mean events, then the generated variable X will describe how
+// many events to skip before performing the operation and computing a new X.
+//
+// The mathematically precise distribution to use for integer wait times is a
+// Geometric distribution, but a Geometric distribution takes slightly more time
+// to compute and when the mean is large (say, 100+), the Geometric distribution
+// is hard to distinguish from the result of ExponentialBiased.
+//
+// This class is thread-compatible.
+class ExponentialBiased {
+ public:
+ // The number of bits set by NextRandom.
+ static constexpr int kPrngNumBits = 48;
+
+ // Generates the floor of an exponentially distributed random variable by
+ // rounding the value down to the nearest integer. The result will be in the
+ // range [0, int64_t max / 2].
+ int64_t Get(int64_t mean);
+
+ // Computes a random number in the range [0, 1<<(kPrngNumBits+1) - 1]
+ //
+ // This is public to enable testing.
+ static uint64_t NextRandom(uint64_t rnd);
+
+ private:
+ void Initialize();
+
+ uint64_t rng_{0};
+ bool initialized_{false};
+};
+
+// Returns the next prng value.
+// pRNG is: aX+b mod c with a = 0x5DEECE66D, b = 0xB, c = 1<<48
+// This is the lrand64 generator.
+inline uint64_t ExponentialBiased::NextRandom(uint64_t rnd) {
+ const uint64_t prng_mult = uint64_t{0x5DEECE66D};
+ const uint64_t prng_add = 0xB;
+ const uint64_t prng_mod_power = 48;
+ const uint64_t prng_mod_mask =
+ ~((~static_cast<uint64_t>(0)) << prng_mod_power);
+ return (prng_mult * rnd + prng_add) & prng_mod_mask;
+}
+
+} // namespace base_internal
+} // namespace absl
+
+#endif // ABSL_BASE_INTERNAL_EXPONENTIAL_BIASED_H_
diff --git a/absl/base/internal/exponential_biased_test.cc b/absl/base/internal/exponential_biased_test.cc
new file mode 100644
index 0000000..09b511d
--- /dev/null
+++ b/absl/base/internal/exponential_biased_test.cc
@@ -0,0 +1,168 @@
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/base/internal/exponential_biased.h"
+
+#include <stddef.h>
+
+#include <cmath>
+#include <cstdint>
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/strings/str_cat.h"
+
+using ::testing::Ge;
+
+namespace absl {
+namespace base_internal {
+
+MATCHER_P2(IsBetween, a, b,
+ absl::StrCat(std::string(negation ? "isn't" : "is"), " between ", a,
+ " and ", b)) {
+ return a <= arg && arg <= b;
+}
+
+// Tests of the quality of the random numbers generated
+// This uses the Anderson Darling test for uniformity.
+// See "Evaluating the Anderson-Darling Distribution" by Marsaglia
+// for details.
+
+// Short cut version of ADinf(z), z>0 (from Marsaglia)
+// This returns the p-value for Anderson Darling statistic in
+// the limit as n-> infinity. For finite n, apply the error fix below.
+double AndersonDarlingInf(double z) {
+ if (z < 2) {
+ return exp(-1.2337141 / z) / sqrt(z) *
+ (2.00012 +
+ (0.247105 -
+ (0.0649821 - (0.0347962 - (0.011672 - 0.00168691 * z) * z) * z) *
+ z) *
+ z);
+ }
+ return exp(
+ -exp(1.0776 -
+ (2.30695 -
+ (0.43424 - (0.082433 - (0.008056 - 0.0003146 * z) * z) * z) * z) *
+ z));
+}
+
+// Corrects the approximation error in AndersonDarlingInf for small values of n
+// Add this to AndersonDarlingInf to get a better approximation
+// (from Marsaglia)
+double AndersonDarlingErrFix(int n, double x) {
+ if (x > 0.8) {
+ return (-130.2137 +
+ (745.2337 -
+ (1705.091 - (1950.646 - (1116.360 - 255.7844 * x) * x) * x) * x) *
+ x) /
+ n;
+ }
+ double cutoff = 0.01265 + 0.1757 / n;
+ if (x < cutoff) {
+ double t = x / cutoff;
+ t = sqrt(t) * (1 - t) * (49 * t - 102);
+ return t * (0.0037 / (n * n) + 0.00078 / n + 0.00006) / n;
+ } else {
+ double t = (x - cutoff) / (0.8 - cutoff);
+ t = -0.00022633 +
+ (6.54034 - (14.6538 - (14.458 - (8.259 - 1.91864 * t) * t) * t) * t) *
+ t;
+ return t * (0.04213 + 0.01365 / n) / n;
+ }
+}
+
+// Returns the AndersonDarling p-value given n and the value of the statistic
+double AndersonDarlingPValue(int n, double z) {
+ double ad = AndersonDarlingInf(z);
+ double errfix = AndersonDarlingErrFix(n, ad);
+ return ad + errfix;
+}
+
+double AndersonDarlingStatistic(const std::vector<double>& random_sample) {
+ int n = random_sample.size();
+ double ad_sum = 0;
+ for (int i = 0; i < n; i++) {
+ ad_sum += (2 * i + 1) *
+ std::log(random_sample[i] * (1 - random_sample[n - 1 - i]));
+ }
+ double ad_statistic = -n - 1 / static_cast<double>(n) * ad_sum;
+ return ad_statistic;
+}
+
+// Tests if the array of doubles is uniformly distributed.
+// Returns the p-value of the Anderson Darling Statistic
+// for the given set of sorted random doubles
+// See "Evaluating the Anderson-Darling Distribution" by
+// Marsaglia and Marsaglia for details.
+double AndersonDarlingTest(const std::vector<double>& random_sample) {
+ double ad_statistic = AndersonDarlingStatistic(random_sample);
+ double p = AndersonDarlingPValue(random_sample.size(), ad_statistic);
+ return p;
+}
+
+// Testing that NextRandom generates uniform random numbers. Applies the
+// Anderson-Darling test for uniformity
+TEST(ExponentialBiasedTest, TestNextRandom) {
+ for (auto n : std::vector<int>({
+ 10, // Check short-range correlation
+ 100, 1000,
+ 10000 // Make sure there's no systemic error
+ })) {
+ uint64_t x = 1;
+ // This assumes that the prng returns 48 bit numbers
+ uint64_t max_prng_value = static_cast<uint64_t>(1) << 48;
+ // Initialize.
+ for (int i = 1; i <= 20; i++) {
+ x = ExponentialBiased::NextRandom(x);
+ }
+ std::vector<uint64_t> int_random_sample(n);
+ // Collect samples
+ for (int i = 0; i < n; i++) {
+ int_random_sample[i] = x;
+ x = ExponentialBiased::NextRandom(x);
+ }
+ // First sort them...
+ std::sort(int_random_sample.begin(), int_random_sample.end());
+ std::vector<double> random_sample(n);
+ // Convert them to uniform randoms (in the range [0,1])
+ for (int i = 0; i < n; i++) {
+ random_sample[i] =
+ static_cast<double>(int_random_sample[i]) / max_prng_value;
+ }
+ // Now compute the Anderson-Darling statistic
+ double ad_pvalue = AndersonDarlingTest(random_sample);
+ EXPECT_GT(std::min(ad_pvalue, 1 - ad_pvalue), 0.0001)
+ << "prng is not uniform: n = " << n << " p = " << ad_pvalue;
+ }
+}
+
+// The generator needs to be available as a thread_local and as a static
+// variable.
+TEST(ExponentialBiasedTest, InitializationModes) {
+ ABSL_CONST_INIT static ExponentialBiased eb_static;
+ EXPECT_THAT(eb_static.Get(2), Ge(0));
+
+#if ABSL_HAVE_THREAD_LOCAL
+ thread_local ExponentialBiased eb_thread;
+ EXPECT_THAT(eb_thread.Get(2), Ge(0));
+#endif
+
+ ExponentialBiased eb_stack;
+ EXPECT_THAT(eb_stack.Get(2), Ge(0));
+}
+
+} // namespace base_internal
+} // namespace absl
diff --git a/absl/base/optimization.h b/absl/base/optimization.h
index 0dcbef3..646523b 100644
--- a/absl/base/optimization.h
+++ b/absl/base/optimization.h
@@ -172,7 +172,7 @@
#if ABSL_HAVE_BUILTIN(__builtin_expect) || \
(defined(__GNUC__) && !defined(__clang__))
#define ABSL_PREDICT_FALSE(x) (__builtin_expect(x, 0))
-#define ABSL_PREDICT_TRUE(x) (__builtin_expect(!!(x), 1))
+#define ABSL_PREDICT_TRUE(x) (__builtin_expect(false || (x), true))
#else
#define ABSL_PREDICT_FALSE(x) (x)
#define ABSL_PREDICT_TRUE(x) (x)
diff --git a/absl/container/BUILD.bazel b/absl/container/BUILD.bazel
index 0894bb2..e60979b 100644
--- a/absl/container/BUILD.bazel
+++ b/absl/container/BUILD.bazel
@@ -493,6 +493,7 @@ cc_library(
":have_sse",
"//absl/base",
"//absl/base:core_headers",
+ "//absl/base:exponential_biased",
"//absl/debugging:stacktrace",
"//absl/memory",
"//absl/synchronization",
diff --git a/absl/container/CMakeLists.txt b/absl/container/CMakeLists.txt
index 933c7a8..aa33659 100644
--- a/absl/container/CMakeLists.txt
+++ b/absl/container/CMakeLists.txt
@@ -538,6 +538,7 @@ absl_cc_library(
${ABSL_DEFAULT_COPTS}
DEPS
absl::base
+ absl::exponential_biased
absl::have_sse
absl::synchronization
)
diff --git a/absl/container/flat_hash_map.h b/absl/container/flat_hash_map.h
index 5c16ac8..283f243 100644
--- a/absl/container/flat_hash_map.h
+++ b/absl/container/flat_hash_map.h
@@ -401,7 +401,7 @@ class flat_hash_map : public absl::container_internal::raw_hash_map<
// for the past-the-end iterator, which is invalidated.
//
// `swap()` requires that the flat hash map's hashing and key equivalence
- // functions be Swappable, and are exchaged using unqualified calls to
+ // functions be Swappable, and are exchanged using unqualified calls to
// non-member `swap()`. If the map's allocator has
// `std::allocator_traits<allocator_type>::propagate_on_container_swap::value`
// set to `true`, the allocators are also exchanged using an unqualified call
diff --git a/absl/container/internal/hashtablez_sampler.cc b/absl/container/internal/hashtablez_sampler.cc
index 054e898..0a7ef61 100644
--- a/absl/container/internal/hashtablez_sampler.cc
+++ b/absl/container/internal/hashtablez_sampler.cc
@@ -21,6 +21,7 @@
#include <limits>
#include "absl/base/attributes.h"
+#include "absl/base/internal/exponential_biased.h"
#include "absl/container/internal/have_sse.h"
#include "absl/debugging/stacktrace.h"
#include "absl/memory/memory.h"
@@ -37,77 +38,13 @@ ABSL_CONST_INIT std::atomic<bool> g_hashtablez_enabled{
ABSL_CONST_INIT std::atomic<int32_t> g_hashtablez_sample_parameter{1 << 10};
ABSL_CONST_INIT std::atomic<int32_t> g_hashtablez_max_samples{1 << 20};
-// Returns the next pseudo-random value.
-// pRNG is: aX+b mod c with a = 0x5DEECE66D, b = 0xB, c = 1<<48
-// This is the lrand64 generator.
-uint64_t NextRandom(uint64_t rnd) {
- const uint64_t prng_mult = uint64_t{0x5DEECE66D};
- const uint64_t prng_add = 0xB;
- const uint64_t prng_mod_power = 48;
- const uint64_t prng_mod_mask = ~(~uint64_t{0} << prng_mod_power);
- return (prng_mult * rnd + prng_add) & prng_mod_mask;
-}
-
-// Generates a geometric variable with the specified mean.
-// This is done by generating a random number between 0 and 1 and applying
-// the inverse cumulative distribution function for an exponential.
-// Specifically: Let m be the inverse of the sample period, then
-// the probability distribution function is m*exp(-mx) so the CDF is
-// p = 1 - exp(-mx), so
-// q = 1 - p = exp(-mx)
-// log_e(q) = -mx
-// -log_e(q)/m = x
-// log_2(q) * (-log_e(2) * 1/m) = x
-// In the code, q is actually in the range 1 to 2**26, hence the -26 below
-//
-int64_t GetGeometricVariable(int64_t mean) {
#if ABSL_HAVE_THREAD_LOCAL
- thread_local
-#else // ABSL_HAVE_THREAD_LOCAL
- // SampleSlow and hence GetGeometricVariable is guarded by a single mutex when
- // there are not thread locals. Thus, a single global rng is acceptable for
- // that case.
- static
-#endif // ABSL_HAVE_THREAD_LOCAL
- uint64_t rng = []() {
- // We don't get well distributed numbers from this so we call
- // NextRandom() a bunch to mush the bits around. We use a global_rand
- // to handle the case where the same thread (by memory address) gets
- // created and destroyed repeatedly.
- ABSL_CONST_INIT static std::atomic<uint32_t> global_rand(0);
- uint64_t r = reinterpret_cast<uint64_t>(&rng) +
- global_rand.fetch_add(1, std::memory_order_relaxed);
- for (int i = 0; i < 20; ++i) {
- r = NextRandom(r);
- }
- return r;
- }();
-
- rng = NextRandom(rng);
-
- // Take the top 26 bits as the random number
- // (This plus the 1<<58 sampling bound give a max possible step of
- // 5194297183973780480 bytes.)
- const uint64_t prng_mod_power = 48; // Number of bits in prng
- // The uint32_t cast is to prevent a (hard-to-reproduce) NAN
- // under piii debug for some binaries.
- double q = static_cast<uint32_t>(rng >> (prng_mod_power - 26)) + 1.0;
- // Put the computed p-value through the CDF of a geometric.
- double interval = (log2(q) - 26) * (-std::log(2.0) * mean);
-
- // Very large values of interval overflow int64_t. If we happen to
- // hit such improbable condition, we simply cheat and clamp interval
- // to largest supported value.
- if (interval > static_cast<double>(std::numeric_limits<int64_t>::max() / 2)) {
- return std::numeric_limits<int64_t>::max() / 2;
- }
-
- // Small values of interval are equivalent to just sampling next time.
- if (interval < 1) {
- return 1;
- }
- return static_cast<int64_t>(interval);
-}
+thread_local absl::base_internal::ExponentialBiased
+ g_exponential_biased_generator;
+#else
+ABSL_CONST_INIT static absl::base_internal::ExponentialBiased
+ g_exponential_biased_generator;
+#endif
} // namespace
@@ -253,8 +190,12 @@ HashtablezInfo* SampleSlow(int64_t* next_sample) {
}
bool first = *next_sample < 0;
- *next_sample = GetGeometricVariable(
+ *next_sample = g_exponential_biased_generator.Get(
g_hashtablez_sample_parameter.load(std::memory_order_relaxed));
+ // Small values of interval are equivalent to just sampling next time.
+ if (*next_sample < 1) {
+ *next_sample = 1;
+ }
// g_hashtablez_enabled can be dynamically flipped, we need to set a threshold
// low enough that we will start sampling in a reasonable time, so we just use
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 42b3c46..9992ba4 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -614,13 +614,17 @@ class raw_hash_set {
iterator() {}
// PRECONDITION: not an end() iterator.
- reference operator*() const { return PolicyTraits::element(slot_); }
+ reference operator*() const {
+ /* To be enabled: assert_is_full(); */
+ return PolicyTraits::element(slot_);
+ }
// PRECONDITION: not an end() iterator.
pointer operator->() const { return &operator*(); }
// PRECONDITION: not an end() iterator.
iterator& operator++() {
+ /* To be enabled: assert_is_full(); */
++ctrl_;
++slot_;
skip_empty_or_deleted();
@@ -634,6 +638,8 @@ class raw_hash_set {
}
friend bool operator==(const iterator& a, const iterator& b) {
+ /* To be enabled: a.assert_is_valid(); */
+ /* To be enabled: b.assert_is_valid(); */
return a.ctrl_ == b.ctrl_;
}
friend bool operator!=(const iterator& a, const iterator& b) {
@@ -644,6 +650,11 @@ class raw_hash_set {
iterator(ctrl_t* ctrl) : ctrl_(ctrl) {} // for end()
iterator(ctrl_t* ctrl, slot_type* slot) : ctrl_(ctrl), slot_(slot) {}
+ void assert_is_full() const { assert(IsFull(*ctrl_)); }
+ void assert_is_valid() const {
+ assert(!ctrl_ || IsFull(*ctrl_) || *ctrl_ == kSentinel);
+ }
+
void skip_empty_or_deleted() {
while (IsEmptyOrDeleted(*ctrl_)) {
// ctrl is not necessarily aligned to Group::kWidth. It is also likely
@@ -1155,7 +1166,7 @@ class raw_hash_set {
// This overload is necessary because otherwise erase<K>(const K&) would be
// a better match if non-const iterator is passed as an argument.
void erase(iterator it) {
- assert(it != end());
+ it.assert_is_full();
PolicyTraits::destroy(&alloc_ref(), it.slot_);
erase_meta_only(it);
}
@@ -1172,12 +1183,14 @@ class raw_hash_set {
template <typename H, typename E>
void merge(raw_hash_set<Policy, H, E, Alloc>& src) { // NOLINT
assert(this != &src);
- for (auto it = src.begin(), e = src.end(); it != e; ++it) {
+ for (auto it = src.begin(), e = src.end(); it != e;) {
+ auto next = std::next(it);
if (PolicyTraits::apply(InsertSlot<false>{*this, std::move(*it.slot_)},
PolicyTraits::element(it.slot_))
.second) {
src.erase_meta_only(it);
}
+ it = next;
}
}
@@ -1187,6 +1200,7 @@ class raw_hash_set {
}
node_type extract(const_iterator position) {
+ position.inner_.assert_is_full();
auto node =
CommonAccess::Transfer<node_type>(alloc_ref(), position.inner_.slot_);
erase_meta_only(position);
diff --git a/absl/container/internal/raw_hash_set_test.cc b/absl/container/internal/raw_hash_set_test.cc
index ed4ca8c..33cfa72 100644
--- a/absl/container/internal/raw_hash_set_test.cc
+++ b/absl/container/internal/raw_hash_set_test.cc
@@ -1837,7 +1837,7 @@ TEST(TableDeathTest, EraseOfEndAsserts) {
IntTable t;
// Extra simple "regexp" as regexp support is highly varied across platforms.
- constexpr char kDeathMsg[] = "it != end";
+ constexpr char kDeathMsg[] = "IsFull";
EXPECT_DEATH_IF_SUPPORTED(t.erase(t.end()), kDeathMsg);
}
diff --git a/absl/copts/AbseilConfigureCopts.cmake b/absl/copts/AbseilConfigureCopts.cmake
index b430873..b442646 100644
--- a/absl/copts/AbseilConfigureCopts.cmake
+++ b/absl/copts/AbseilConfigureCopts.cmake
@@ -5,10 +5,29 @@ set(ABSL_LSAN_LINKOPTS "")
set(ABSL_HAVE_LSAN OFF)
set(ABSL_DEFAULT_LINKOPTS "")
+if("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86_64")
+ if (MSVC)
+ set(ABSL_RANDOM_RANDEN_COPTS "${ABSL_RANDOM_HWAES_MSVC_X64_FLAGS}")
+ else()
+ set(ABSL_RANDOM_RANDEN_COPTS "${ABSL_RANDOM_HWAES_X64_FLAGS}")
+ endif()
+elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "arm")
+ if ("${CMAKE_SIZEOF_VOID_P}" STREQUAL "8")
+ set(ABSL_RANDOM_RANDEN_COPTS "${ABSL_RANDOM_HWAES_ARM64_FLAGS}")
+ elseif("${CMAKE_SIZEOF_VOID_P}" STREQUAL "4")
+ set(ABSL_RANDOM_RANDEN_COPTS "${ABSL_RANDOM_HWAES_ARM32_FLAGS}")
+ else()
+ message(WARNING "Value of CMAKE_SIZEOF_VOID_P (${CMAKE_SIZEOF_VOID_P}) is not supported.")
+ endif()
+else()
+ message(WARNING "Value of CMAKE_SYSTEM_PROCESSOR (${CMAKE_SYSTEM_PROCESSOR}) is unknown and cannot be used to set ABSL_RANDOM_RANDEN_COPTS")
+ set(ABSL_RANDOM_RANDEN_COPTS "")
+endif()
+
+
if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
set(ABSL_DEFAULT_COPTS "${ABSL_GCC_FLAGS}")
set(ABSL_TEST_COPTS "${ABSL_GCC_FLAGS};${ABSL_GCC_TEST_FLAGS}")
- set(ABSL_RANDOM_RANDEN_COPTS "${ABSL_RANDOM_HWAES_X64_FLAGS}")
elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
# MATCHES so we get both Clang and AppleClang
if(MSVC)
@@ -16,11 +35,9 @@ elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
set(ABSL_DEFAULT_COPTS "${ABSL_CLANG_CL_FLAGS}")
set(ABSL_TEST_COPTS "${ABSL_CLANG_CL_FLAGS};${ABSL_CLANG_CL_TEST_FLAGS}")
set(ABSL_DEFAULT_LINKOPTS "${ABSL_MSVC_LINKOPTS}")
- set(ABSL_RANDOM_RANDEN_COPTS "${ABSL_RANDOM_HWAES_MSVC_X64_FLAGS}")
else()
set(ABSL_DEFAULT_COPTS "${ABSL_LLVM_FLAGS}")
set(ABSL_TEST_COPTS "${ABSL_LLVM_FLAGS};${ABSL_LLVM_TEST_FLAGS}")
- set(ABSL_RANDOM_RANDEN_COPTS "${ABSL_RANDOM_HWAES_X64_FLAGS}")
if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
# AppleClang doesn't have lsan
# https://developer.apple.com/documentation/code_diagnostics
@@ -34,12 +51,10 @@ elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
set(ABSL_DEFAULT_COPTS "${ABSL_MSVC_FLAGS}")
set(ABSL_TEST_COPTS "${ABSL_MSVC_FLAGS};${ABSL_MSVC_TEST_FLAGS}")
set(ABSL_DEFAULT_LINKOPTS "${ABSL_MSVC_LINKOPTS}")
- set(ABSL_RANDOM_RANDEN_COPTS "${ABSL_RANDOM_HWAES_MSVC_X64_FLAGS}")
else()
message(WARNING "Unknown compiler: ${CMAKE_CXX_COMPILER}. Building with no default flags")
set(ABSL_DEFAULT_COPTS "")
set(ABSL_TEST_COPTS "")
- set(ABSL_RANDOM_RANDEN_COPTS "")
endif()
if("${CMAKE_CXX_STANDARD}" EQUAL 98)
diff --git a/absl/random/BUILD.bazel b/absl/random/BUILD.bazel
index 828f134..c3520df 100644
--- a/absl/random/BUILD.bazel
+++ b/absl/random/BUILD.bazel
@@ -69,10 +69,10 @@ cc_library(
"//absl/base:base_internal",
"//absl/base:core_headers",
"//absl/meta:type_traits",
- "//absl/random/internal:distribution_impl",
"//absl/random/internal:distributions",
"//absl/random/internal:fast_uniform_bits",
"//absl/random/internal:fastmath",
+ "//absl/random/internal:generate_real",
"//absl/random/internal:iostream_state_saver",
"//absl/random/internal:traits",
"//absl/random/internal:uniform_helper",
diff --git a/absl/random/CMakeLists.txt b/absl/random/CMakeLists.txt
index 19dd2ca..289854f 100644
--- a/absl/random/CMakeLists.txt
+++ b/absl/random/CMakeLists.txt
@@ -58,7 +58,7 @@ absl_cc_library(
DEPS
absl::base_internal
absl::core_headers
- absl::random_internal_distribution_impl
+ absl::random_internal_generate_real
absl::random_internal_distributions
absl::random_internal_fast_uniform_bits
absl::random_internal_fastmath
@@ -543,19 +543,18 @@ absl_cc_library(
# Internal-only target, do not depend on directly.
absl_cc_library(
NAME
- random_internal_distribution_impl
+ random_internal_generate_real
HDRS
- "internal/distribution_impl.h"
+ "internal/generate_real.h"
COPTS
${ABSL_DEFAULT_COPTS}
LINKOPTS
${ABSL_DEFAULT_LINKOPTS}
DEPS
absl::bits
- absl::config
- absl::int128
absl::random_internal_fastmath
absl::random_internal_traits
+ absl::type_traits
)
# Internal-only target, do not depend on directly.
@@ -767,9 +766,9 @@ absl_cc_test(
# Internal-only target, do not depend on directly.
absl_cc_test(
NAME
- random_internal_distribution_impl_test
+ random_internal_generate_real_test
SRCS
- "internal/distribution_impl_test.cc"
+ "internal/generate_real_test.cc"
COPTS
${ABSL_TEST_COPTS}
LINKOPTS
@@ -777,8 +776,7 @@ absl_cc_test(
DEPS
absl::bits
absl::flags
- absl::int128
- absl::random_internal_distribution_impl
+ absl::random_internal_generate_real
gtest_main
)
@@ -1029,7 +1027,6 @@ absl_cc_library(
${ABSL_DEFAULT_LINKOPTS}
DEPS
absl::core_headers
- absl::random_internal_distribution_impl
absl::random_internal_fast_uniform_bits
absl::random_internal_iostream_state_saver
absl::random_internal_traits
diff --git a/absl/random/beta_distribution.h b/absl/random/beta_distribution.h
index e29894f..b09b02f 100644
--- a/absl/random/beta_distribution.h
+++ b/absl/random/beta_distribution.h
@@ -22,9 +22,10 @@
#include <ostream>
#include <type_traits>
-#include "absl/random/internal/distribution_impl.h"
+#include "absl/meta/type_traits.h"
#include "absl/random/internal/fast_uniform_bits.h"
#include "absl/random/internal/fastmath.h"
+#include "absl/random/internal/generate_real.h"
#include "absl/random/internal/iostream_state_saver.h"
namespace absl {
@@ -275,15 +276,21 @@ typename beta_distribution<RealType>::result_type
beta_distribution<RealType>::AlgorithmJoehnk(
URBG& g, // NOLINT(runtime/references)
const param_type& p) {
+ using random_internal::GeneratePositiveTag;
+ using random_internal::GenerateRealFromBits;
+ using real_type =
+ absl::conditional_t<std::is_same<RealType, float>::value, float, double>;
+
// Based on Joehnk, M. D. Erzeugung von betaverteilten und gammaverteilten
// Zufallszahlen. Metrika 8.1 (1964): 5-15.
// This method is described in Knuth, Vol 2 (Third Edition), pp 134.
- using RandU64ToReal = typename random_internal::RandU64ToReal<result_type>;
- using random_internal::PositiveValueT;
+
result_type u, v, x, y, z;
for (;;) {
- u = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g));
- v = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g));
+ u = GenerateRealFromBits<real_type, GeneratePositiveTag, false>(
+ fast_u64_(g));
+ v = GenerateRealFromBits<real_type, GeneratePositiveTag, false>(
+ fast_u64_(g));
// Direct method. std::pow is slow for float, so rely on the optimizer to
// remove the std::pow() path for that case.
@@ -327,12 +334,14 @@ typename beta_distribution<RealType>::result_type
beta_distribution<RealType>::AlgorithmCheng(
URBG& g, // NOLINT(runtime/references)
const param_type& p) {
+ using random_internal::GeneratePositiveTag;
+ using random_internal::GenerateRealFromBits;
+ using real_type =
+ absl::conditional_t<std::is_same<RealType, float>::value, float, double>;
+
// Based on Cheng, Russell CH. Generating beta variates with nonintegral
// shape parameters. Communications of the ACM 21.4 (1978): 317-322.
// (https://dl.acm.org/citation.cfm?id=359482).
- using RandU64ToReal = typename random_internal::RandU64ToReal<result_type>;
- using random_internal::PositiveValueT;
-
static constexpr result_type kLogFour =
result_type(1.3862943611198906188344642429163531361); // log(4)
static constexpr result_type kS =
@@ -341,8 +350,10 @@ beta_distribution<RealType>::AlgorithmCheng(
const bool use_algorithm_ba = (p.method_ == param_type::CHENG_BA);
result_type u1, u2, v, w, z, r, s, t, bw_inv, lhs;
for (;;) {
- u1 = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g));
- u2 = RandU64ToReal::template Value<PositiveValueT, false>(fast_u64_(g));
+ u1 = GenerateRealFromBits<real_type, GeneratePositiveTag, false>(
+ fast_u64_(g));
+ u2 = GenerateRealFromBits<real_type, GeneratePositiveTag, false>(
+ fast_u64_(g));
v = p.y_ * std::log(u1 / (1 - u1));
w = p.a_ * std::exp(v);
bw_inv = result_type(1) / (p.b_ + w);
diff --git a/absl/random/beta_distribution_test.cc b/absl/random/beta_distribution_test.cc
index 966ad08..d0111b3 100644
--- a/absl/random/beta_distribution_test.cc
+++ b/absl/random/beta_distribution_test.cc
@@ -92,7 +92,7 @@ TYPED_TEST(BetaDistributionInterfaceTest, SerializeTest) {
for (TypeParam alpha : kValues) {
for (TypeParam beta : kValues) {
ABSL_INTERNAL_LOG(
- INFO, absl::StrFormat("Smoke test for Beta(%f, %f)", alpha, beta));
+ INFO, absl::StrFormat("Smoke test for Beta(%a, %a)", alpha, beta));
param_type param(alpha, beta);
absl::beta_distribution<TypeParam> before(alpha, beta);
diff --git a/absl/random/exponential_distribution.h b/absl/random/exponential_distribution.h
index c8af197..24abf57 100644
--- a/absl/random/exponential_distribution.h
+++ b/absl/random/exponential_distribution.h
@@ -21,8 +21,9 @@
#include <limits>
#include <type_traits>
-#include "absl/random/internal/distribution_impl.h"
+#include "absl/meta/type_traits.h"
#include "absl/random/internal/fast_uniform_bits.h"
+#include "absl/random/internal/generate_real.h"
#include "absl/random/internal/iostream_state_saver.h"
namespace absl {
@@ -118,9 +119,14 @@ typename exponential_distribution<RealType>::result_type
exponential_distribution<RealType>::operator()(
URBG& g, // NOLINT(runtime/references)
const param_type& p) {
- using random_internal::NegativeValueT;
- const result_type u = random_internal::RandU64ToReal<
- result_type>::template Value<NegativeValueT, false>(fast_u64_(g));
+ using random_internal::GenerateNegativeTag;
+ using random_internal::GenerateRealFromBits;
+ using real_type =
+ absl::conditional_t<std::is_same<RealType, float>::value, float, double>;
+
+ const result_type u = GenerateRealFromBits<real_type, GenerateNegativeTag,
+ false>(fast_u64_(g)); // U(-1, 0)
+
// log1p(-x) is mathematically equivalent to log(1 - x) but has more
// accuracy for x near zero.
return p.neg_inv_lambda_ * std::log1p(u);
diff --git a/absl/random/gaussian_distribution.h b/absl/random/gaussian_distribution.h
index 1d1347b..c299e94 100644
--- a/absl/random/gaussian_distribution.h
+++ b/absl/random/gaussian_distribution.h
@@ -28,8 +28,8 @@
#include <limits>
#include <type_traits>
-#include "absl/random/internal/distribution_impl.h"
#include "absl/random/internal/fast_uniform_bits.h"
+#include "absl/random/internal/generate_real.h"
#include "absl/random/internal/iostream_state_saver.h"
namespace absl {
@@ -207,12 +207,18 @@ namespace random_internal {
template <typename URBG>
inline double gaussian_distribution_base::zignor_fallback(URBG& g, bool neg) {
+ using random_internal::GeneratePositiveTag;
+ using random_internal::GenerateRealFromBits;
+
// This fallback path happens approximately 0.05% of the time.
double x, y;
do {
// kRInv = 1/r, U(0, 1)
- x = kRInv * std::log(RandU64ToDouble<PositiveValueT, false>(fast_u64_(g)));
- y = -std::log(RandU64ToDouble<PositiveValueT, false>(fast_u64_(g)));
+ x = kRInv *
+ std::log(GenerateRealFromBits<double, GeneratePositiveTag, false>(
+ fast_u64_(g)));
+ y = -std::log(
+ GenerateRealFromBits<double, GeneratePositiveTag, false>(fast_u64_(g)));
} while ((y + y) < (x * x));
return neg ? (x - kR) : (kR - x);
}
@@ -220,6 +226,10 @@ inline double gaussian_distribution_base::zignor_fallback(URBG& g, bool neg) {
template <typename URBG>
inline double gaussian_distribution_base::zignor(
URBG& g) { // NOLINT(runtime/references)
+ using random_internal::GeneratePositiveTag;
+ using random_internal::GenerateRealFromBits;
+ using random_internal::GenerateSignedTag;
+
while (true) {
// We use a single uint64_t to generate both a double and a strip.
// These bits are unused when the generated double is > 1/2^5.
@@ -227,7 +237,8 @@ inline double gaussian_distribution_base::zignor(
// values (those smaller than 1/2^5, which all end up on the left tail).
uint64_t bits = fast_u64_(g);
int i = static_cast<int>(bits & kMask); // pick a random strip
- double j = RandU64ToDouble<SignedValueT, false>(bits); // U(-1, 1)
+ double j = GenerateRealFromBits<double, GenerateSignedTag, false>(
+ bits); // U(-1, 1)
const double x = j * zg_.x[i];
// Retangular box. Handles >97% of all cases.
@@ -244,7 +255,8 @@ inline double gaussian_distribution_base::zignor(
}
// i > 0: Wedge samples using precomputed values.
- double v = RandU64ToDouble<PositiveValueT, false>(fast_u64_(g)); // U(0, 1)
+ double v = GenerateRealFromBits<double, GeneratePositiveTag, false>(
+ fast_u64_(g)); // U(0, 1)
if ((zg_.f[i + 1] + v * (zg_.f[i] - zg_.f[i + 1])) <
std::exp(-0.5 * x * x)) {
return x;
diff --git a/absl/random/internal/BUILD.bazel b/absl/random/internal/BUILD.bazel
index ec58cec..91388d1 100644
--- a/absl/random/internal/BUILD.bazel
+++ b/absl/random/internal/BUILD.bazel
@@ -175,9 +175,9 @@ cc_library(
)
cc_library(
- name = "distribution_impl",
+ name = "generate_real",
hdrs = [
- "distribution_impl.h",
+ "generate_real.h",
],
copts = ABSL_DEFAULT_COPTS,
linkopts = ABSL_DEFAULT_LINKOPTS,
@@ -185,8 +185,7 @@ cc_library(
":fastmath",
":traits",
"//absl/base:bits",
- "//absl/base:config",
- "//absl/numeric:int128",
+ "//absl/meta:type_traits",
],
)
@@ -398,16 +397,17 @@ cc_test(
)
cc_test(
- name = "distribution_impl_test",
+ name = "generate_real_test",
size = "small",
- srcs = ["distribution_impl_test.cc"],
+ srcs = [
+ "generate_real_test.cc",
+ ],
copts = ABSL_TEST_COPTS,
linkopts = ABSL_DEFAULT_LINKOPTS,
deps = [
- ":distribution_impl",
+ ":generate_real",
"//absl/base:bits",
"//absl/flags:flag",
- "//absl/numeric:int128",
"@com_google_googletest//:gtest_main",
],
)
diff --git a/absl/random/internal/distribution_impl.h b/absl/random/internal/distribution_impl.h
deleted file mode 100644
index 49b3e1a..0000000
--- a/absl/random/internal/distribution_impl.h
+++ /dev/null
@@ -1,194 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#ifndef ABSL_RANDOM_INTERNAL_DISTRIBUTION_IMPL_H_
-#define ABSL_RANDOM_INTERNAL_DISTRIBUTION_IMPL_H_
-
-// This file contains some implementation details which are used by one or more
-// of the absl random number distributions.
-
-#include <cfloat>
-#include <cstddef>
-#include <cstdint>
-#include <cstring>
-#include <limits>
-#include <type_traits>
-
-#if (defined(_WIN32) || defined(_WIN64)) && defined(_M_IA64)
-#include <intrin.h> // NOLINT(build/include_order)
-#pragma intrinsic(_umul128)
-#define ABSL_INTERNAL_USE_UMUL128 1
-#endif
-
-#include "absl/base/config.h"
-#include "absl/base/internal/bits.h"
-#include "absl/numeric/int128.h"
-#include "absl/random/internal/fastmath.h"
-#include "absl/random/internal/traits.h"
-
-namespace absl {
-namespace random_internal {
-
-// Creates a double from `bits`, with the template fields controlling the
-// output.
-//
-// RandU64To is both more efficient and generates more unique values in the
-// result interval than known implementations of std::generate_canonical().
-//
-// The `Signed` parameter controls whether positive, negative, or both are
-// returned (thus affecting the output interval).
-// When Signed == SignedValueT, range is U(-1, 1)
-// When Signed == NegativeValueT, range is U(-1, 0)
-// When Signed == PositiveValueT, range is U(0, 1)
-//
-// When the `IncludeZero` parameter is true, the function may return 0 for some
-// inputs, otherwise it never returns 0.
-//
-// The `ExponentBias` parameter determines the scale of the output range by
-// adjusting the exponent.
-//
-// When a value in U(0,1) is required, use:
-// RandU64ToDouble<PositiveValueT, true, 0>();
-//
-// When a value in U(-1,1) is required, use:
-// RandU64ToDouble<SignedValueT, false, 0>() => U(-1, 1)
-// This generates more distinct values than the mathematically equivalent
-// expression `U(0, 1) * 2.0 - 1.0`, and is preferable.
-//
-// Scaling the result by powers of 2 (and avoiding a multiply) is also possible:
-// RandU64ToDouble<PositiveValueT, false, 1>(); => U(0, 2)
-// RandU64ToDouble<PositiveValueT, false, -1>(); => U(0, 0.5)
-//
-
-// Tristate types controlling the output.
-struct PositiveValueT {};
-struct NegativeValueT {};
-struct SignedValueT {};
-
-// RandU64ToDouble is the double-result variant of RandU64To, described above.
-template <typename Signed, bool IncludeZero, int ExponentBias = 0>
-inline double RandU64ToDouble(uint64_t bits) {
- static_assert(std::is_same<Signed, PositiveValueT>::value ||
- std::is_same<Signed, NegativeValueT>::value ||
- std::is_same<Signed, SignedValueT>::value,
- "");
-
- // Maybe use the left-most bit for a sign bit.
- uint64_t sign = std::is_same<Signed, NegativeValueT>::value
- ? 0x8000000000000000ull
- : 0; // Sign bits.
-
- if (std::is_same<Signed, SignedValueT>::value) {
- sign = bits & 0x8000000000000000ull;
- bits = bits & 0x7FFFFFFFFFFFFFFFull;
- }
- if (IncludeZero) {
- if (bits == 0u) return 0;
- }
-
- // Number of leading zeros is mapped to the exponent: 2^-clz
- int clz = base_internal::CountLeadingZeros64(bits);
- // Shift number left to erase leading zeros.
- bits <<= IncludeZero ? clz : (clz & 63);
-
- // Shift number right to remove bits that overflow double mantissa. The
- // direction of the shift depends on `clz`.
- bits >>= (64 - DBL_MANT_DIG);
-
- // Compute IEEE 754 double exponent.
- // In the Signed case, bits is a 63-bit number with a 0 msb. Adjust the
- // exponent to account for that.
- const uint64_t exp =
- (std::is_same<Signed, SignedValueT>::value ? 1023U : 1022U) +
- static_cast<uint64_t>(ExponentBias - clz);
- constexpr int kExp = DBL_MANT_DIG - 1;
- // Construct IEEE 754 double from exponent and mantissa.
- const uint64_t val = sign | (exp << kExp) | (bits & ((1ULL << kExp) - 1U));
-
- double res;
- static_assert(sizeof(res) == sizeof(val), "double is not 64 bit");
- // Memcpy value from "val" to "res" to avoid aliasing problems. Assumes that
- // endian-ness is same for double and uint64_t.
- std::memcpy(&res, &val, sizeof(res));
-
- return res;
-}
-
-// RandU64ToFloat is the float-result variant of RandU64To, described above.
-template <typename Signed, bool IncludeZero, int ExponentBias = 0>
-inline float RandU64ToFloat(uint64_t bits) {
- static_assert(std::is_same<Signed, PositiveValueT>::value ||
- std::is_same<Signed, NegativeValueT>::value ||
- std::is_same<Signed, SignedValueT>::value,
- "");
-
- // Maybe use the left-most bit for a sign bit.
- uint64_t sign = std::is_same<Signed, NegativeValueT>::value
- ? 0x80000000ul
- : 0; // Sign bits.
-
- if (std::is_same<Signed, SignedValueT>::value) {
- uint64_t a = bits & 0x8000000000000000ull;
- sign = static_cast<uint32_t>(a >> 32);
- bits = bits & 0x7FFFFFFFFFFFFFFFull;
- }
- if (IncludeZero) {
- if (bits == 0u) return 0;
- }
-
- // Number of leading zeros is mapped to the exponent: 2^-clz
- int clz = base_internal::CountLeadingZeros64(bits);
- // Shift number left to erase leading zeros.
- bits <<= IncludeZero ? clz : (clz & 63);
- // Shift number right to remove bits that overflow double mantissa. The
- // direction of the shift depends on `clz`.
- bits >>= (64 - FLT_MANT_DIG);
-
- // Construct IEEE 754 float exponent.
- // In the Signed case, bits is a 63-bit number with a 0 msb. Adjust the
- // exponent to account for that.
- const uint32_t exp =
- (std::is_same<Signed, SignedValueT>::value ? 127U : 126U) +
- static_cast<uint32_t>(ExponentBias - clz);
- constexpr int kExp = FLT_MANT_DIG - 1;
- const uint32_t val = sign | (exp << kExp) | (bits & ((1U << kExp) - 1U));
-
- float res;
- static_assert(sizeof(res) == sizeof(val), "float is not 32 bit");
- // Assumes that endian-ness is same for float and uint32_t.
- std::memcpy(&res, &val, sizeof(res));
-
- return res;
-}
-
-template <typename Result>
-struct RandU64ToReal {
- template <typename Signed, bool IncludeZero, int ExponentBias = 0>
- static inline Result Value(uint64_t bits) {
- return RandU64ToDouble<Signed, IncludeZero, ExponentBias>(bits);
- }
-};
-
-template <>
-struct RandU64ToReal<float> {
- template <typename Signed, bool IncludeZero, int ExponentBias = 0>
- static inline float Value(uint64_t bits) {
- return RandU64ToFloat<Signed, IncludeZero, ExponentBias>(bits);
- }
-};
-
-} // namespace random_internal
-} // namespace absl
-
-#endif // ABSL_RANDOM_INTERNAL_DISTRIBUTION_IMPL_H_
diff --git a/absl/random/internal/generate_real.h b/absl/random/internal/generate_real.h
new file mode 100644
index 0000000..246d863
--- /dev/null
+++ b/absl/random/internal/generate_real.h
@@ -0,0 +1,144 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_RANDOM_INTERNAL_GENERATE_REAL_H_
+#define ABSL_RANDOM_INTERNAL_GENERATE_REAL_H_
+
+// This file contains some implementation details which are used by one or more
+// of the absl random number distributions.
+
+#include <cstdint>
+#include <cstring>
+#include <limits>
+#include <type_traits>
+
+#include "absl/base/internal/bits.h"
+#include "absl/meta/type_traits.h"
+#include "absl/random/internal/fastmath.h"
+#include "absl/random/internal/traits.h"
+
+namespace absl {
+namespace random_internal {
+
+// Tristate tag types controlling the output of GenerateRealFromBits.
+struct GeneratePositiveTag {};
+struct GenerateNegativeTag {};
+struct GenerateSignedTag {};
+
+// GenerateRealFromBits generates a single real value from a single 64-bit
+// `bits` with template fields controlling the output.
+//
+// The `SignedTag` parameter controls whether positive, negative,
+// or either signed/unsigned may be returned.
+// When SignedTag == GeneratePositiveTag, range is U(0, 1)
+// When SignedTag == GenerateNegativeTag, range is U(-1, 0)
+// When SignedTag == GenerateSignedTag, range is U(-1, 1)
+//
+// When the `IncludeZero` parameter is true, the function may return 0 for some
+// inputs, otherwise it never returns 0.
+//
+// When a value in U(0,1) is required, use:
+// Uniform64ToReal<double, PositiveValueT, true>;
+//
+// When a value in U(-1,1) is required, use:
+// Uniform64ToReal<double, SignedValueT, false>;
+//
+// This generates more distinct values than the mathematical equivalent
+// `U(0, 1) * 2.0 - 1.0`.
+//
+// Scaling the result by powers of 2 (and avoiding a multiply) is also possible:
+// GenerateRealFromBits<double>(..., -1); => U(0, 0.5)
+// GenerateRealFromBits<double>(..., 1); => U(0, 2)
+//
+template <typename RealType, // Real type, either float or double.
+ typename SignedTag = GeneratePositiveTag, // Whether a positive,
+ // negative, or signed
+ // value is generated.
+ bool IncludeZero = true>
+inline RealType GenerateRealFromBits(uint64_t bits, int exp_bias = 0) {
+ using real_type = RealType;
+ using uint_type = absl::conditional_t<std::is_same<real_type, float>::value,
+ uint32_t, uint64_t>;
+
+ static_assert(
+ (std::is_same<double, real_type>::value ||
+ std::is_same<float, real_type>::value),
+ "GenerateRealFromBits must be parameterized by either float or double.");
+
+ static_assert(sizeof(uint_type) == sizeof(real_type),
+ "Mismatched unsinged and real types.");
+
+ static_assert((std::numeric_limits<real_type>::is_iec559 &&
+ std::numeric_limits<real_type>::radix == 2),
+ "RealType representation is not IEEE 754 binary.");
+
+ static_assert((std::is_same<SignedTag, GeneratePositiveTag>::value ||
+ std::is_same<SignedTag, GenerateNegativeTag>::value ||
+ std::is_same<SignedTag, GenerateSignedTag>::value),
+ "");
+
+ static constexpr int kExp = std::numeric_limits<real_type>::digits - 1;
+ static constexpr uint_type kMask = (static_cast<uint_type>(1) << kExp) - 1u;
+ static constexpr int kUintBits = sizeof(uint_type) * 8;
+
+ int exp = exp_bias + int{std::numeric_limits<real_type>::max_exponent - 2};
+
+ // Determine the sign bit.
+ // Depending on the SignedTag, this may use the left-most bit
+ // or it may be a constant value.
+ uint_type sign = std::is_same<SignedTag, GenerateNegativeTag>::value
+ ? (static_cast<uint_type>(1) << (kUintBits - 1))
+ : 0;
+ if (std::is_same<SignedTag, GenerateSignedTag>::value) {
+ if (std::is_same<uint_type, uint64_t>::value) {
+ sign = bits & uint64_t{0x8000000000000000};
+ }
+ if (std::is_same<uint_type, uint32_t>::value) {
+ const uint64_t tmp = bits & uint64_t{0x8000000000000000};
+ sign = static_cast<uint32_t>(tmp >> 32);
+ }
+ // adjust the bits and the exponent to account for removing
+ // the leading bit.
+ bits = bits & uint64_t{0x7FFFFFFFFFFFFFFF};
+ exp++;
+ }
+ if (IncludeZero) {
+ if (bits == 0u) return 0;
+ }
+
+ // Number of leading zeros is mapped to the exponent: 2^-clz
+ // bits is 0..01xxxxxx. After shifting, we're left with 1xxx...0..0
+ int clz = base_internal::CountLeadingZeros64(bits);
+ bits <<= (IncludeZero ? clz : (clz & 63)); // remove 0-bits.
+ exp -= clz; // set the exponent.
+ bits >>= (63 - kExp);
+
+ // Construct the 32-bit or 64-bit IEEE 754 floating-point value from
+ // the individual fields: sign, exp, mantissa(bits).
+ uint_type val =
+ (std::is_same<SignedTag, GeneratePositiveTag>::value ? 0u : sign) |
+ (static_cast<uint_type>(exp) << kExp) |
+ (static_cast<uint_type>(bits) & kMask);
+
+ // bit_cast to the output-type
+ real_type result;
+ memcpy(static_cast<void*>(&result), static_cast<const void*>(&val),
+ sizeof(result));
+ return result;
+}
+
+} // namespace random_internal
+} // namespace absl
+
+#endif // ABSL_RANDOM_INTERNAL_GENERATE_REAL_H_
diff --git a/absl/random/internal/distribution_impl_test.cc b/absl/random/internal/generate_real_test.cc
index fcc1690..aa02f0c 100644
--- a/absl/random/internal/distribution_impl_test.cc
+++ b/absl/random/internal/generate_real_test.cc
@@ -12,57 +12,74 @@
// See the License for the specific language governing permissions and
// limitations under the License.
-#include "absl/random/internal/distribution_impl.h"
+#include "absl/random/internal/generate_real.h"
+
+#include <cfloat>
+#include <cstddef>
+#include <cstdint>
+#include <string>
#include "gtest/gtest.h"
#include "absl/base/internal/bits.h"
#include "absl/flags/flag.h"
-#include "absl/numeric/int128.h"
ABSL_FLAG(int64_t, absl_random_test_trials, 50000,
"Number of trials for the probability tests.");
-using absl::random_internal::NegativeValueT;
-using absl::random_internal::PositiveValueT;
-using absl::random_internal::RandU64ToDouble;
-using absl::random_internal::RandU64ToFloat;
-using absl::random_internal::SignedValueT;
+using absl::random_internal::GenerateNegativeTag;
+using absl::random_internal::GeneratePositiveTag;
+using absl::random_internal::GenerateRealFromBits;
+using absl::random_internal::GenerateSignedTag;
namespace {
-TEST(DistributionImplTest, U64ToFloat_Positive_NoZero_Test) {
+TEST(GenerateRealTest, U64ToFloat_Positive_NoZero_Test) {
auto ToFloat = [](uint64_t a) {
- return RandU64ToFloat<PositiveValueT, false>(a);
+ return GenerateRealFromBits<float, GeneratePositiveTag, false>(a);
};
EXPECT_EQ(ToFloat(0x0000000000000000), 2.710505431e-20f);
EXPECT_EQ(ToFloat(0x0000000000000001), 5.421010862e-20f);
EXPECT_EQ(ToFloat(0x8000000000000000), 0.5);
+ EXPECT_EQ(ToFloat(0x8000000000000001), 0.5);
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), 0.9999999404f);
}
-TEST(DistributionImplTest, U64ToFloat_Positive_Zero_Test) {
+TEST(GenerateRealTest, U64ToFloat_Positive_Zero_Test) {
auto ToFloat = [](uint64_t a) {
- return RandU64ToFloat<PositiveValueT, true>(a);
+ return GenerateRealFromBits<float, GeneratePositiveTag, true>(a);
};
EXPECT_EQ(ToFloat(0x0000000000000000), 0.0);
EXPECT_EQ(ToFloat(0x0000000000000001), 5.421010862e-20f);
EXPECT_EQ(ToFloat(0x8000000000000000), 0.5);
+ EXPECT_EQ(ToFloat(0x8000000000000001), 0.5);
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), 0.9999999404f);
}
-TEST(DistributionImplTest, U64ToFloat_Negative_NoZero_Test) {
+TEST(GenerateRealTest, U64ToFloat_Negative_NoZero_Test) {
auto ToFloat = [](uint64_t a) {
- return RandU64ToFloat<NegativeValueT, false>(a);
+ return GenerateRealFromBits<float, GenerateNegativeTag, false>(a);
};
EXPECT_EQ(ToFloat(0x0000000000000000), -2.710505431e-20f);
EXPECT_EQ(ToFloat(0x0000000000000001), -5.421010862e-20f);
EXPECT_EQ(ToFloat(0x8000000000000000), -0.5);
+ EXPECT_EQ(ToFloat(0x8000000000000001), -0.5);
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), -0.9999999404f);
}
-TEST(DistributionImplTest, U64ToFloat_Signed_NoZero_Test) {
+TEST(GenerateRealTest, U64ToFloat_Negative_Zero_Test) {
auto ToFloat = [](uint64_t a) {
- return RandU64ToFloat<SignedValueT, false>(a);
+ return GenerateRealFromBits<float, GenerateNegativeTag, true>(a);
+ };
+ EXPECT_EQ(ToFloat(0x0000000000000000), 0.0);
+ EXPECT_EQ(ToFloat(0x0000000000000001), -5.421010862e-20f);
+ EXPECT_EQ(ToFloat(0x8000000000000000), -0.5);
+ EXPECT_EQ(ToFloat(0x8000000000000001), -0.5);
+ EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), -0.9999999404f);
+}
+
+TEST(GenerateRealTest, U64ToFloat_Signed_NoZero_Test) {
+ auto ToFloat = [](uint64_t a) {
+ return GenerateRealFromBits<float, GenerateSignedTag, false>(a);
};
EXPECT_EQ(ToFloat(0x0000000000000000), 5.421010862e-20f);
EXPECT_EQ(ToFloat(0x0000000000000001), 1.084202172e-19f);
@@ -72,9 +89,9 @@ TEST(DistributionImplTest, U64ToFloat_Signed_NoZero_Test) {
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), -0.9999999404f);
}
-TEST(DistributionImplTest, U64ToFloat_Signed_Zero_Test) {
+TEST(GenerateRealTest, U64ToFloat_Signed_Zero_Test) {
auto ToFloat = [](uint64_t a) {
- return RandU64ToFloat<SignedValueT, true>(a);
+ return GenerateRealFromBits<float, GenerateSignedTag, true>(a);
};
EXPECT_EQ(ToFloat(0x0000000000000000), 0);
EXPECT_EQ(ToFloat(0x0000000000000001), 1.084202172e-19f);
@@ -84,9 +101,9 @@ TEST(DistributionImplTest, U64ToFloat_Signed_Zero_Test) {
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), -0.9999999404f);
}
-TEST(DistributionImplTest, U64ToFloat_Signed_Bias_Test) {
+TEST(GenerateRealTest, U64ToFloat_Signed_Bias_Test) {
auto ToFloat = [](uint64_t a) {
- return RandU64ToFloat<SignedValueT, true, 1>(a);
+ return GenerateRealFromBits<float, GenerateSignedTag, true>(a, 1);
};
EXPECT_EQ(ToFloat(0x0000000000000000), 0);
EXPECT_EQ(ToFloat(0x0000000000000001), 2 * 1.084202172e-19f);
@@ -96,9 +113,9 @@ TEST(DistributionImplTest, U64ToFloat_Signed_Bias_Test) {
EXPECT_EQ(ToFloat(0xFFFFFFFFFFFFFFFF), 2 * -0.9999999404f);
}
-TEST(DistributionImplTest, U64ToFloatTest) {
+TEST(GenerateRealTest, U64ToFloatTest) {
auto ToFloat = [](uint64_t a) -> float {
- return RandU64ToFloat<PositiveValueT, true>(a);
+ return GenerateRealFromBits<float, GeneratePositiveTag, true>(a);
};
EXPECT_EQ(ToFloat(0x0000000000000000), 0.0f);
@@ -150,44 +167,60 @@ TEST(DistributionImplTest, U64ToFloatTest) {
}
}
-TEST(DistributionImplTest, U64ToDouble_Positive_NoZero_Test) {
+TEST(GenerateRealTest, U64ToDouble_Positive_NoZero_Test) {
auto ToDouble = [](uint64_t a) {
- return RandU64ToDouble<PositiveValueT, false>(a);
+ return GenerateRealFromBits<double, GeneratePositiveTag, false>(a);
};
EXPECT_EQ(ToDouble(0x0000000000000000), 2.710505431213761085e-20);
EXPECT_EQ(ToDouble(0x0000000000000001), 5.42101086242752217004e-20);
EXPECT_EQ(ToDouble(0x0000000000000002), 1.084202172485504434e-19);
EXPECT_EQ(ToDouble(0x8000000000000000), 0.5);
+ EXPECT_EQ(ToDouble(0x8000000000000001), 0.5);
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), 0.999999999999999888978);
}
-TEST(DistributionImplTest, U64ToDouble_Positive_Zero_Test) {
+TEST(GenerateRealTest, U64ToDouble_Positive_Zero_Test) {
auto ToDouble = [](uint64_t a) {
- return RandU64ToDouble<PositiveValueT, true>(a);
+ return GenerateRealFromBits<double, GeneratePositiveTag, true>(a);
};
EXPECT_EQ(ToDouble(0x0000000000000000), 0.0);
EXPECT_EQ(ToDouble(0x0000000000000001), 5.42101086242752217004e-20);
EXPECT_EQ(ToDouble(0x8000000000000000), 0.5);
+ EXPECT_EQ(ToDouble(0x8000000000000001), 0.5);
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), 0.999999999999999888978);
}
-TEST(DistributionImplTest, U64ToDouble_Negative_NoZero_Test) {
+TEST(GenerateRealTest, U64ToDouble_Negative_NoZero_Test) {
auto ToDouble = [](uint64_t a) {
- return RandU64ToDouble<NegativeValueT, false>(a);
+ return GenerateRealFromBits<double, GenerateNegativeTag, false>(a);
};
EXPECT_EQ(ToDouble(0x0000000000000000), -2.710505431213761085e-20);
EXPECT_EQ(ToDouble(0x0000000000000001), -5.42101086242752217004e-20);
EXPECT_EQ(ToDouble(0x0000000000000002), -1.084202172485504434e-19);
EXPECT_EQ(ToDouble(0x8000000000000000), -0.5);
+ EXPECT_EQ(ToDouble(0x8000000000000001), -0.5);
+ EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978);
+}
+
+TEST(GenerateRealTest, U64ToDouble_Negative_Zero_Test) {
+ auto ToDouble = [](uint64_t a) {
+ return GenerateRealFromBits<double, GenerateNegativeTag, true>(a);
+ };
+
+ EXPECT_EQ(ToDouble(0x0000000000000000), 0.0);
+ EXPECT_EQ(ToDouble(0x0000000000000001), -5.42101086242752217004e-20);
+ EXPECT_EQ(ToDouble(0x0000000000000002), -1.084202172485504434e-19);
+ EXPECT_EQ(ToDouble(0x8000000000000000), -0.5);
+ EXPECT_EQ(ToDouble(0x8000000000000001), -0.5);
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978);
}
-TEST(DistributionImplTest, U64ToDouble_Signed_NoZero_Test) {
+TEST(GenerateRealTest, U64ToDouble_Signed_NoZero_Test) {
auto ToDouble = [](uint64_t a) {
- return RandU64ToDouble<SignedValueT, false>(a);
+ return GenerateRealFromBits<double, GenerateSignedTag, false>(a);
};
EXPECT_EQ(ToDouble(0x0000000000000000), 5.42101086242752217004e-20);
@@ -198,9 +231,9 @@ TEST(DistributionImplTest, U64ToDouble_Signed_NoZero_Test) {
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978);
}
-TEST(DistributionImplTest, U64ToDouble_Signed_Zero_Test) {
+TEST(GenerateRealTest, U64ToDouble_Signed_Zero_Test) {
auto ToDouble = [](uint64_t a) {
- return RandU64ToDouble<SignedValueT, true>(a);
+ return GenerateRealFromBits<double, GenerateSignedTag, true>(a);
};
EXPECT_EQ(ToDouble(0x0000000000000000), 0);
EXPECT_EQ(ToDouble(0x0000000000000001), 1.084202172485504434e-19);
@@ -210,9 +243,9 @@ TEST(DistributionImplTest, U64ToDouble_Signed_Zero_Test) {
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978);
}
-TEST(DistributionImplTest, U64ToDouble_Signed_Bias_Test) {
+TEST(GenerateRealTest, U64ToDouble_GenerateSignedTag_Bias_Test) {
auto ToDouble = [](uint64_t a) {
- return RandU64ToDouble<SignedValueT, true, -1>(a);
+ return GenerateRealFromBits<double, GenerateSignedTag, true>(a, -1);
};
EXPECT_EQ(ToDouble(0x0000000000000000), 0);
EXPECT_EQ(ToDouble(0x0000000000000001), 1.084202172485504434e-19 / 2);
@@ -222,9 +255,9 @@ TEST(DistributionImplTest, U64ToDouble_Signed_Bias_Test) {
EXPECT_EQ(ToDouble(0xFFFFFFFFFFFFFFFF), -0.999999999999999888978 / 2);
}
-TEST(DistributionImplTest, U64ToDoubleTest) {
+TEST(GenerateRealTest, U64ToDoubleTest) {
auto ToDouble = [](uint64_t a) {
- return RandU64ToDouble<PositiveValueT, true>(a);
+ return GenerateRealFromBits<double, GeneratePositiveTag, true>(a);
};
EXPECT_EQ(ToDouble(0x0000000000000000), 0.0);
@@ -296,9 +329,9 @@ TEST(DistributionImplTest, U64ToDoubleTest) {
}
}
-TEST(DistributionImplTest, U64ToDoubleSignedTest) {
+TEST(GenerateRealTest, U64ToDoubleSignedTest) {
auto ToDouble = [](uint64_t a) {
- return RandU64ToDouble<SignedValueT, false>(a);
+ return GenerateRealFromBits<double, GenerateSignedTag, false>(a);
};
EXPECT_EQ(ToDouble(0x0000000000000000), 5.42101086242752217004e-20);
@@ -379,10 +412,10 @@ TEST(DistributionImplTest, U64ToDoubleSignedTest) {
}
}
-TEST(DistributionImplTest, ExhaustiveFloat) {
+TEST(GenerateRealTest, ExhaustiveFloat) {
using absl::base_internal::CountLeadingZeros64;
auto ToFloat = [](uint64_t a) {
- return RandU64ToFloat<PositiveValueT, true>(a);
+ return GenerateRealFromBits<float, GeneratePositiveTag, true>(a);
};
// Rely on RandU64ToFloat generating values from greatest to least when
diff --git a/absl/random/log_uniform_int_distribution.h b/absl/random/log_uniform_int_distribution.h
index ac43416..956a690 100644
--- a/absl/random/log_uniform_int_distribution.h
+++ b/absl/random/log_uniform_int_distribution.h
@@ -23,8 +23,8 @@
#include <ostream>
#include <type_traits>
-#include "absl/random/internal/distribution_impl.h"
#include "absl/random/internal/fastmath.h"
+#include "absl/random/internal/generate_real.h"
#include "absl/random/internal/iostream_state_saver.h"
#include "absl/random/internal/traits.h"
#include "absl/random/uniform_int_distribution.h"
diff --git a/absl/random/poisson_distribution.h b/absl/random/poisson_distribution.h
index 7750b1c..23a953f 100644
--- a/absl/random/poisson_distribution.h
+++ b/absl/random/poisson_distribution.h
@@ -22,9 +22,9 @@
#include <ostream>
#include <type_traits>
-#include "absl/random/internal/distribution_impl.h"
#include "absl/random/internal/fast_uniform_bits.h"
#include "absl/random/internal/fastmath.h"
+#include "absl/random/internal/generate_real.h"
#include "absl/random/internal/iostream_state_saver.h"
namespace absl {
@@ -164,9 +164,9 @@ typename poisson_distribution<IntType>::result_type
poisson_distribution<IntType>::operator()(
URBG& g, // NOLINT(runtime/references)
const param_type& p) {
- using random_internal::PositiveValueT;
- using random_internal::RandU64ToDouble;
- using random_internal::SignedValueT;
+ using random_internal::GeneratePositiveTag;
+ using random_internal::GenerateRealFromBits;
+ using random_internal::GenerateSignedTag;
if (p.split_ != 0) {
// Use Knuth's algorithm with range splitting to avoid floating-point
@@ -186,7 +186,8 @@ poisson_distribution<IntType>::operator()(
for (int split = p.split_; split > 0; --split) {
double r = 1.0;
do {
- r *= RandU64ToDouble<PositiveValueT, true>(fast_u64_(g));
+ r *= GenerateRealFromBits<double, GeneratePositiveTag, true>(
+ fast_u64_(g)); // U(-1, 0)
++n;
} while (r > p.emu_);
--n;
@@ -205,10 +206,11 @@ poisson_distribution<IntType>::operator()(
// and k = max(f).
const double a = p.mean_ + 0.5;
for (;;) {
- const double u =
- RandU64ToDouble<PositiveValueT, false>(fast_u64_(g)); // (0, 1)
- const double v =
- RandU64ToDouble<SignedValueT, false>(fast_u64_(g)); // (-1, 1)
+ const double u = GenerateRealFromBits<double, GeneratePositiveTag, false>(
+ fast_u64_(g)); // U(0, 1)
+ const double v = GenerateRealFromBits<double, GenerateSignedTag, false>(
+ fast_u64_(g)); // U(-1, 1)
+
const double x = std::floor(p.s_ * v / u + a);
if (x < 0) continue; // f(negative) = 0
const double rhs = x * p.lmu_;
diff --git a/absl/random/uniform_int_distribution.h b/absl/random/uniform_int_distribution.h
index 02aa376..dc8ba8c 100644
--- a/absl/random/uniform_int_distribution.h
+++ b/absl/random/uniform_int_distribution.h
@@ -34,7 +34,6 @@
#include <type_traits>
#include "absl/base/optimization.h"
-#include "absl/random/internal/distribution_impl.h"
#include "absl/random/internal/fast_uniform_bits.h"
#include "absl/random/internal/iostream_state_saver.h"
#include "absl/random/internal/traits.h"
diff --git a/absl/random/uniform_real_distribution.h b/absl/random/uniform_real_distribution.h
index 336abb3..bf2ed2c 100644
--- a/absl/random/uniform_real_distribution.h
+++ b/absl/random/uniform_real_distribution.h
@@ -39,8 +39,9 @@
#include <limits>
#include <type_traits>
-#include "absl/random/internal/distribution_impl.h"
+#include "absl/meta/type_traits.h"
#include "absl/random/internal/fast_uniform_bits.h"
+#include "absl/random/internal/generate_real.h"
#include "absl/random/internal/iostream_state_saver.h"
namespace absl {
@@ -76,6 +77,7 @@ class uniform_real_distribution {
// is not possible, so value generation cannot use the full range of the
// real type.
assert(range_ <= (std::numeric_limits<result_type>::max)());
+ assert(std::isfinite(range_));
}
result_type a() const { return lo_; }
@@ -151,10 +153,15 @@ template <typename URBG>
typename uniform_real_distribution<RealType>::result_type
uniform_real_distribution<RealType>::operator()(
URBG& gen, const param_type& p) { // NOLINT(runtime/references)
- using random_internal::PositiveValueT;
+ using random_internal::GeneratePositiveTag;
+ using random_internal::GenerateRealFromBits;
+ using real_type =
+ absl::conditional_t<std::is_same<RealType, float>::value, float, double>;
+
while (true) {
- const result_type sample = random_internal::RandU64ToReal<
- result_type>::template Value<PositiveValueT, true>(fast_u64_(gen));
+ const result_type sample =
+ GenerateRealFromBits<real_type, GeneratePositiveTag, true>(
+ fast_u64_(gen));
const result_type res = p.a() + (sample * p.range_);
if (res < p.b() || p.range_ <= 0 || !std::isfinite(p.range_)) {
return res;