From 078b89b3c046d230ef3ad39494e5852184eb528b Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Wed, 23 Oct 2019 19:35:39 -0700 Subject: Export of internal Abseil changes -- e54b9c7bbb0c58475676c268e2e19c69f4bce48a by Jorg Brown : 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 : 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 : Fix typo in flat_hash_map.h: exchaged -> exchanged PiperOrigin-RevId: 276295792 -- 7bbd8d18276eb110c8335743e35fceb662ddf3d6 by Samuel Benzaquen : Add assertions to verify use of iterators. PiperOrigin-RevId: 276283300 -- 677398a8ffcb1f59182cffe57a4fe7ff147a0404 by Laramie Leavitt : Migrate distribution_impl.h/cc to generate_real.h/cc. Combine the methods RandU64To into a single method: GenerateRealFromBits(). Remove rejection sampling from absl::uniform_real_distribution. PiperOrigin-RevId: 276158675 -- c60c9d11d24b0c546329d998e78e15a84b3153f5 by Abseil Team : Internal change PiperOrigin-RevId: 276126962 -- 4c840cab6a8d86efa29b397cafaf7520eece68cc by Andy Soffer : 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 : Internal change PiperOrigin-RevId: 276097452 GitOrigin-RevId: e54b9c7bbb0c58475676c268e2e19c69f4bce48a Change-Id: I02d84454bb71ab21ad3d39650acf6cc6e36f58d7 --- absl/random/beta_distribution.h | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) (limited to 'absl/random/beta_distribution.h') 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 #include -#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::result_type beta_distribution::AlgorithmJoehnk( URBG& g, // NOLINT(runtime/references) const param_type& p) { + using random_internal::GeneratePositiveTag; + using random_internal::GenerateRealFromBits; + using real_type = + absl::conditional_t::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; - using random_internal::PositiveValueT; + result_type u, v, x, y, z; for (;;) { - u = RandU64ToReal::template Value(fast_u64_(g)); - v = RandU64ToReal::template Value(fast_u64_(g)); + u = GenerateRealFromBits( + fast_u64_(g)); + v = GenerateRealFromBits( + 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::result_type beta_distribution::AlgorithmCheng( URBG& g, // NOLINT(runtime/references) const param_type& p) { + using random_internal::GeneratePositiveTag; + using random_internal::GenerateRealFromBits; + using real_type = + absl::conditional_t::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; - 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::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(fast_u64_(g)); - u2 = RandU64ToReal::template Value(fast_u64_(g)); + u1 = GenerateRealFromBits( + fast_u64_(g)); + u2 = GenerateRealFromBits( + 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); -- cgit v1.2.3