Export of internal Abseil changes

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f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>:

Slight restructuring of absl/random/internal randen implementation.

Convert round-keys.inc into randen_round_keys.cc file.

Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts.

Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed.

PiperOrigin-RevId: 312190313

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dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 312167304

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f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>:

Cleanup StrFormat extensions a little.

PiperOrigin-RevId: 312166336

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9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 312105213

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9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>:

Complete IGNORE_TYPE macro renaming.

PiperOrigin-RevId: 311999699

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64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>:

Switch to fixed bytes specific default value.

This fixes the Abseil Flags for big endian platforms.

PiperOrigin-RevId: 311844448

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bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>:

Change many distribution tests to use pcg_engine as a deterministic source of entropy.

It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests.

Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values.

This changelist does the latter.

PiperOrigin-RevId: 311840096
GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266
Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a

1 files changed, 5 insertions, 1 deletions

diff --git a/absl/random/zipf_distribution_test.cc b/absl/random/zipf_distribution_test.cc
index 4d4a0fcf793b..f8cf70e0dddf 100644
--- a/absl/random/zipf_distribution_test.cc
+++ b/absl/random/zipf_distribution_test.cc
@@ -27,6 +27,7 @@
 #include "gtest/gtest.h"
 #include "absl/base/internal/raw_logging.h"
 #include "absl/random/internal/chi_square.h"
+#include "absl/random/internal/pcg_engine.h"
 #include "absl/random/internal/sequence_urbg.h"
 #include "absl/random/random.h"
 #include "absl/strings/str_cat.h"
@@ -213,7 +214,10 @@ class ZipfTest : public testing::TestWithParam<zipf_u64::param_type>,
  public:
   ZipfTest() : ZipfModel(GetParam().k(), GetParam().q(), GetParam().v()) {}
 
-  absl::InsecureBitGen rng_;
+  // We use a fixed bit generator for distribution accuracy tests.  This allows
+  // these tests to be deterministic, while still testing the qualify of the
+  // implementation.
+  absl::random_internal::pcg64_2018_engine rng_{0x2B7E151628AED2A6};
 };
 
 TEST_P(ZipfTest, ChiSquaredTest) {