From b0735979d778a768caee207f01f327535cbd2140 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Tue, 2 Mar 2021 14:28:07 -0800 Subject: Export of internal Abseil changes -- a74bdb72c3a6983e08a805938dd0e20e97d55bba by Abseil Team : Fix typo: calcualte -> calculate PiperOrigin-RevId: 360515509 -- 3ddf8ac194e81a13e9de095e59dd061c1beacfe3 by Benjamin Barenblat : Make tests tolerant of FMA contraction Weaken Duration.ToDoubleSecondsCheckEdgeCases and Duration.ToDoubleSecondsCheckRandom to make them less sensitive to fused multiply/add contraction. PiperOrigin-RevId: 360297653 GitOrigin-RevId: a74bdb72c3a6983e08a805938dd0e20e97d55bba Change-Id: I0c55383bc13040ea77511c4130d142368103dc57 --- absl/numeric/internal/bits.h | 2 +- absl/time/duration_test.cc | 18 +++++++++++------- 2 files changed, 12 insertions(+), 8 deletions(-) (limited to 'absl') diff --git a/absl/numeric/internal/bits.h b/absl/numeric/internal/bits.h index e51941d7..bfef06bc 100644 --- a/absl/numeric/internal/bits.h +++ b/absl/numeric/internal/bits.h @@ -343,7 +343,7 @@ ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline typename std::enable_if::value, T>::type BitCeilNonPowerOf2(T x) { // If T is narrower than unsigned, it undergoes promotion to unsigned when we - // shift. We calcualte the number of bits added by the wider type. + // shift. We calculate the number of bits added by the wider type. return BitCeilPromotionHelper( static_cast(std::numeric_limits::digits - CountLeadingZeroes(x)), T{sizeof(T) >= sizeof(unsigned) ? 0 diff --git a/absl/time/duration_test.cc b/absl/time/duration_test.cc index 4d85a2c4..fb28fa98 100644 --- a/absl/time/duration_test.cc +++ b/absl/time/duration_test.cc @@ -1369,10 +1369,13 @@ TEST(Duration, SmallConversions) { EXPECT_THAT(ToTimeval(absl::Nanoseconds(2000)), TimevalMatcher(tv)); } -void VerifySameAsMul(double time_as_seconds, int* const misses) { +void VerifyApproxSameAsMul(double time_as_seconds, int* const misses) { auto direct_seconds = absl::Seconds(time_as_seconds); auto mul_by_one_second = time_as_seconds * absl::Seconds(1); - if (direct_seconds != mul_by_one_second) { + // These are expected to differ by up to one tick due to fused multiply/add + // contraction. + if (absl::AbsDuration(direct_seconds - mul_by_one_second) > + absl::time_internal::MakeDuration(0, 1u)) { if (*misses > 10) return; ASSERT_LE(++(*misses), 10) << "Too many errors, not reporting more."; EXPECT_EQ(direct_seconds, mul_by_one_second) @@ -1384,7 +1387,8 @@ void VerifySameAsMul(double time_as_seconds, int* const misses) { // For a variety of interesting durations, we find the exact point // where one double converts to that duration, and the very next double // converts to the next duration. For both of those points, verify that -// Seconds(point) returns the same duration as point * Seconds(1.0) +// Seconds(point) returns a duration near point * Seconds(1.0). (They may +// not be exactly equal due to fused multiply/add contraction.) TEST(Duration, ToDoubleSecondsCheckEdgeCases) { constexpr uint32_t kTicksPerSecond = absl::time_internal::kTicksPerSecond; constexpr auto duration_tick = absl::time_internal::MakeDuration(0, 1u); @@ -1423,8 +1427,8 @@ TEST(Duration, ToDoubleSecondsCheckEdgeCases) { } // Now low_edge is the highest double that converts to Duration d, // and high_edge is the lowest double that converts to Duration after_d. - VerifySameAsMul(low_edge, &misses); - VerifySameAsMul(high_edge, &misses); + VerifyApproxSameAsMul(low_edge, &misses); + VerifyApproxSameAsMul(high_edge, &misses); } } } @@ -1444,8 +1448,8 @@ TEST(Duration, ToDoubleSecondsCheckRandom) { int misses = 0; for (int i = 0; i < 1000000; ++i) { double d = std::exp(uniform(gen)); - VerifySameAsMul(d, &misses); - VerifySameAsMul(-d, &misses); + VerifyApproxSameAsMul(d, &misses); + VerifyApproxSameAsMul(-d, &misses); } } -- cgit v1.2.3