summaryrefslogtreecommitdiff
path: root/absl/random/internal/randen_detect.cc
diff options
context:
space:
mode:
authorGravatar Abseil Team <absl-team@google.com>2019-08-08 10:56:58 -0700
committerGravatar CJ Johnson <johnsoncj@google.com>2019-08-08 14:19:45 -0400
commitaa844899c937bde5d2b24f276b59997e5b668bde (patch)
treecd18e64150abc74b85bbbf6abf990f66fa47cacd /absl/random/internal/randen_detect.cc
parentfcb104594b0bb4b8ac306cb2f55ecdad40974683 (diff)
Creation of LTS branch "lts_2019_08_08"20190808
- 9ee91d3e430fb33a4590486573792eb0fa146c2d Export of internal Abseil changes by Abseil Team <absl-team@google.com> - 8efba58a3b656e9b41fb0471ae6453425a61c520 Export of internal Abseil changes by Abseil Team <absl-team@google.com> - b49b8d16b67ec6912899684b732e6367f258cfdb Export of internal Abseil changes by Abseil Team <absl-team@google.com> - 67222ffc4c83d918ce8395aa61769eeb77df4c4d Export of internal Abseil changes by Abseil Team <absl-team@google.com> - c5c4db4f5191fe5e76cbf68dcc71fb28702f7d2b Export of internal Abseil changes by Abseil Team <absl-team@google.com> - 14550beb3b7b97195e483fb74b5efb906395c31e Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 52e88ee56b72cf32bc66534d942c7398ce481331 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 36d37ab992038f52276ca66b9da80c1cf0f57dc2 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - ad1485c8986246b2ae9105e512738d0e97aec887 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - f3840bc5e33ce4932e35986cf3718450c6f02af2 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 278b26058c036833a4f7f3047d3f4d9296527f87 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - c6c3c1b498e4ee939b24be59cae29d59c3863be8 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 44efe96dfca674a17b45ca53fc77fb69f1e29bf4 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 3c98fcc0461bd2a4b9c149d4748a7373a225cf4b Merge pull request #340 from jtsylve/macos_cxx17_fix by Matt Calabrese <38107210+mattcalabrese-google@users.noreply.github.com> - 74d91756c11bc22f9b0108b94da9326f7f9e376f Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - e6b050212c859fbaf67abac76105da10ec348274 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - c964fcffac27bd4a9ff67fe393410dd1146ef8b8 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 72e09a54d993b192db32be14c65adf7e9bd08c31 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - d65e19dfcd8697076f68598c0131c6930cdcd74d Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 5162fc83d2f3b79a9753ed59594c43966afdd37a Merge pull request #336 from shields/patch-2 by Shaindel Schwartz <31392632+shaindelschwartz@users.noreply.github.com> - 0389f7bf58fa41f35b3ad60be61d32f31e4f8ed6 Merge pull request #335 from shields/patch-1 by Shaindel Schwartz <31392632+shaindelschwartz@users.noreply.github.com> - e9324d926a9189e222741fce6e676f0944661a72 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 43ef2148c0936ebf7cb4be6b19927a9d9d145b8f Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - a13d3df2b3ba68aeead92e2d078fba0510d55024 Merge pull request #323 from gosnik/master by Gennadiy Rozental <rogeeff@google.com> - 310a11865c97c5cdcc42a4ee2c2e3578423afe69 Merge pull request #324 from RasPat1/patch-1 by Gennadiy Rozental <rogeeff@google.com> - 8f11724067248acc330b4d1f12f0c76d03f2cfb1 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - b1dd425423380126f6441ce4fbb6f8f6c75b793a Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 361cb8a9db2f2130442389fd80593255be26d681 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 0238ab0a831f179518c1a814f9584e99da2d75a3 Merge pull request #321 from christoph-cullmann/c4245_fix... by Xiaoyi Zhang <zhangxy988@gmail.com> - 61c9bf3e3e1c28a4aa6d7f1be4b37fd473bb5529 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - bc9101f9982391019521161a36179b52555ed212 Merge pull request #320 from christoph-cullmann/master by Xiaoyi Zhang <zhangxy988@gmail.com> - 2f76a9bf50046e396138cc8eeb3cdc17b7a5ac24 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 4adaf5490921f13028b55018c9f550277de5aebb Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 27c30ec671cb7b5ba84c4e79feff7fd0b0ac6338 Avoid undefined behavior when nullptr is passed to memcpy... by Roman Gershman <romange@gmail.com> - ce65f5ac3cbf897bb5e3de1a51d80fd00866abaa Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - a18fc7461e7409c2ad64e28537261db1e02e76fa Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 8a394b19c149cab50534b04c5e21d42bc2217a7d Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - daf381e8535a1f1f1b8a75966a74e7cca63dee89 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - fa00c321073c7ea40a4fc3dfc8a06309eae3d025 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 436ba6c4a0ea3a06eca6e055f9c8d296bf3bae12 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 0cbdc774b97f7e80ab60dbe2ed4eaca3b2e33fc8 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 27c2f6e2f3b5929fbd322b0f0ca392eb02efd9f8 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - aa468ad75539619b47979911297efbb629c52e44 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - cd86d0d20ab167c33b23d3875db68d1d4bad3a3b Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 33841c5c963aa9c3f096ef8e6c1e71624b941940 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - ca3f87560a0eef716195cadf66dc6b938a579ec6 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - d902eb869bcfacc1bad14933ed9af4bed006d481 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - a02f62f456f2c4a7ecf2be3104fe0c6e16fbad9a Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 0b545b460141b882b244a1efcef7621d59278160 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - dbae8764fbd429bf7d7745e24bcf73962177a7c0 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 044da8a29c923506af0f0b46bc46f43c1e1300b5 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 6cc6ac44e065b9e8975fadfd6ccb99cbcf89aac4 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 666fc1266bccfd8e6eaaa084e7b42580bb8eb199 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 93dfcf74cb5fccae3da07897d8613ae6cab958a0 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 2c8421e1c6cef0da9e8a20b01c15256ec9ec116d Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 5b65c4af5107176555b23a638e5947686410ac1f Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - eab2078b53c9e3d9d240135c09d27e3393acb50a Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 253eb7416421661873afbaa33828a850db978541 [CMake] Set correct flags for clang-cl (#278) by Loo Rong Jie <loorongjie@gmail.com> - e75672f6afc7e8f23ee7b532e86d1b3b9be3984e Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - bf29470384a101b307873b26d358433138c857fc Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 6fd827124facd8336981e73218997f9e73029b4f Merge pull request #280 from chiumichael/master by Derek Mauro <761129+derekmauro@users.noreply.github.com> - 7c7754fb3ed9ffb57d35fe8658f3ba4d73a31e72 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 256be563447a315f2a7993ec669460ba475fa86a Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 88a152ae747c3c42dc9167d46c590929b048d436 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - c1cecb25a94c075725e9d2640f6b978a8f61957b Implement Span::first and Span::last from C++20 (#274) by Girts <girtsf@users.noreply.github.com> - 38b704384cd2f17590b3922b97744be0b43622c9 Changed HTTP URLs to HTTPS where possible (#270) by nik7273 <nik8470@gmail.com> - febc5ee6a92d0eb7dac1fceaa6c648cf6521b4dc Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 9fdf5e5b805412cb2a2e624d3e9a11588120465f Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 419f3184f8ebcdb23105295eadd2a569f3351eb9 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - b312c3cb53a0aad75a85ac2bf57c4a614fbd48d4 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 308ce31528a7edfa39f5f6d36142278a0ae1bf45 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 93d155bc4414f6c121bb1f19dba9fdb27c8943bc Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 426eaa4aa44e4580418bee46c1bd13911151bfb1 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 2901ec32a919311384d6ad4194e2d927c06831f7 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - d78310fe5a82f2e0e6e16509ef8079c8d7e4674e Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - a4cb1c8ba61531a63f9d309eea01ac1d43d8371d Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 540e2537b92cd4abfae6ceddfe24304345461f32 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 89ea0c5ff34aaa5855cfc7aa41f323b8a0ef0ede Merge pull request #255 from uilianries/hotfix/conan by ahedberg <ahedberg@google.com> - 5e0dcf72c64fae912184d2e0de87195fe8f0a425 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 0dffca4e36791c7beeda04da10460b534283948a Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 6b4201f9ef650637510a21b8d6cbcc3bee4a606f Fix GCC8 warnings by Boris Staletic <boris.staletic@gmail.com> - 0b1e6d417b414aad9282e32e8c49c719edeb63c1 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - efccc502606bed768e50a6cd5806d8eb13e4e935 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 5e6a78131f7bd5940218462c07d88cdefdd75dbe Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 5eea0f713c14ac17788b83e496f11903f8e2bbb0 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 66f9becbb98ecc083f4db349b4b1e0ca9de93b15 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 018b4db1d73ec8238e6dc4b17fd9e1fd7468d0ed Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 9449ae94397f2fd683851348e25ed8c93f75b3b9 Merge pull request #243 from ThomsonTan/FixIntrinsic by Alex Strelnikov <strel@google.com> - b16aeb6756bdab08cdf12d40baab5b51f7d15b16 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 7ffbe09f3d85504bd018783bbe1e2c12992fe47c Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 01b471d9f3ebef27f5aaca14b66509099fa8cd6c Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 7bd8f36c741c7cbe311611d7981bf38ba04c6fef Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 968a34ffdaadd7db062a9621dfbdf8b2d16e05af Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 3e2e9b5557e76d098de4b8a2a659125b98ca519b Merge pull request #231 from uilianries/feature/conan by Mark Barolak <mbxx@users.noreply.github.com> - 111ca7060a6ff50115ca85b59f6b5d8c8c5e9105 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 389ec3f906f018661a5308458d623d01f96d7b23 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 8fbcdb90952c57828c4a9c2f6d79fcd7cae9088f Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 455dc17ba1af9635f0b60155bc565bc572a1e722 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - f197d7c72a54064cfde5a2058f1513a4a0ee36fb Export of internal Abseil changes. by Abseil Team <absl-team@google.com> - 284378a71b32dfb3af4e3661f585e671d1b603a3 Export of internal Abseil changes. by Abseil Team <absl-team@google.com> GitOrigin-RevId: 9ee91d3e430fb33a4590486573792eb0fa146c2d Change-Id: Ia06e548bc106cc9d136f6c65714be6645317aced
Diffstat (limited to 'absl/random/internal/randen_detect.cc')
-rw-r--r--absl/random/internal/randen_detect.cc221
1 files changed, 221 insertions, 0 deletions
diff --git a/absl/random/internal/randen_detect.cc b/absl/random/internal/randen_detect.cc
new file mode 100644
index 00000000..610ae319
--- /dev/null
+++ b/absl/random/internal/randen_detect.cc
@@ -0,0 +1,221 @@
+// 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.
+
+// HERMETIC NOTE: The randen_hwaes target must not introduce duplicate
+// symbols from arbitrary system and other headers, since it may be built
+// with different flags from other targets, using different levels of
+// optimization, potentially introducing ODR violations.
+
+#include "absl/random/internal/randen_detect.h"
+
+#include <cstdint>
+#include <cstring>
+
+#include "absl/random/internal/platform.h"
+
+#if defined(ABSL_ARCH_X86_64)
+#define ABSL_INTERNAL_USE_X86_CPUID
+#elif defined(ABSL_ARCH_PPC) || defined(ABSL_ARCH_ARM) || \
+ defined(ABSL_ARCH_AARCH64)
+#if defined(__ANDROID__)
+#define ABSL_INTERNAL_USE_ANDROID_GETAUXVAL
+#define ABSL_INTERNAL_USE_GETAUXVAL
+#elif defined(__linux__)
+#define ABSL_INTERNAL_USE_LINUX_GETAUXVAL
+#define ABSL_INTERNAL_USE_GETAUXVAL
+#endif
+#endif
+
+#if defined(ABSL_INTERNAL_USE_X86_CPUID)
+#if defined(_WIN32) || defined(_WIN64)
+#include <intrin.h> // NOLINT(build/include_order)
+#pragma intrinsic(__cpuid)
+#else
+// MSVC-equivalent __cpuid intrinsic function.
+static void __cpuid(int cpu_info[4], int info_type) {
+ __asm__ volatile("cpuid \n\t"
+ : "=a"(cpu_info[0]), "=b"(cpu_info[1]), "=c"(cpu_info[2]),
+ "=d"(cpu_info[3])
+ : "a"(info_type), "c"(0));
+}
+#endif
+#endif // ABSL_INTERNAL_USE_X86_CPUID
+
+// On linux, just use the c-library getauxval call.
+#if defined(ABSL_INTERNAL_USE_LINUX_GETAUXVAL)
+
+extern "C" unsigned long getauxval(unsigned long type); // NOLINT(runtime/int)
+
+static uint32_t GetAuxval(uint32_t hwcap_type) {
+ return static_cast<uint32_t>(getauxval(hwcap_type));
+}
+
+#endif
+
+// On android, probe the system's C library for getauxval().
+// This is the same technique used by the android NDK cpu features library
+// as well as the google open-source cpu_features library.
+//
+// TODO(absl-team): Consider implementing a fallback of directly reading
+// /proc/self/auxval.
+#if defined(ABSL_INTERNAL_USE_ANDROID_GETAUXVAL)
+#include <dlfcn.h>
+
+static uint32_t GetAuxval(uint32_t hwcap_type) {
+ // NOLINTNEXTLINE(runtime/int)
+ typedef unsigned long (*getauxval_func_t)(unsigned long);
+
+ dlerror(); // Cleaning error state before calling dlopen.
+ void* libc_handle = dlopen("libc.so", RTLD_NOW);
+ if (!libc_handle) {
+ return 0;
+ }
+ uint32_t result = 0;
+ void* sym = dlsym(libc_handle, "getauxval");
+ if (sym) {
+ getauxval_func_t func;
+ memcpy(&func, &sym, sizeof(func));
+ result = static_cast<uint32_t>((*func)(hwcap_type));
+ }
+ dlclose(libc_handle);
+ return result;
+}
+
+#endif
+
+namespace absl {
+inline namespace lts_2019_08_08 {
+namespace random_internal {
+
+// The default return at the end of the function might be unreachable depending
+// on the configuration. Ignore that warning.
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunreachable-code-return"
+#endif
+
+// CPUSupportsRandenHwAes returns whether the CPU is a microarchitecture
+// which supports the crpyto/aes instructions or extensions necessary to use the
+// accelerated RandenHwAes implementation.
+//
+// 1. For x86 it is sufficient to use the CPUID instruction to detect whether
+// the cpu supports AES instructions. Done.
+//
+// Fon non-x86 it is much more complicated.
+//
+// 2. When ABSL_INTERNAL_USE_GETAUXVAL is defined, use getauxval() (either
+// the direct c-library version, or the android probing version which loads
+// libc), and read the hardware capability bits.
+// This is based on the technique used by boringssl uses to detect
+// cpu capabilities, and should allow us to enable crypto in the android
+// builds where it is supported.
+//
+// 3. Use the default for the compiler architecture.
+//
+
+bool CPUSupportsRandenHwAes() {
+#if defined(ABSL_INTERNAL_USE_X86_CPUID)
+ // 1. For x86: Use CPUID to detect the required AES instruction set.
+ int regs[4];
+ __cpuid(reinterpret_cast<int*>(regs), 1);
+ return regs[2] & (1 << 25); // AES
+
+#elif defined(ABSL_INTERNAL_USE_GETAUXVAL)
+ // 2. Use getauxval() to read the hardware bits and determine
+ // cpu capabilities.
+
+#define AT_HWCAP 16
+#define AT_HWCAP2 26
+#if defined(ABSL_ARCH_PPC)
+ // For Power / PPC: Expect that the cpu supports VCRYPTO
+ // See https://members.openpowerfoundation.org/document/dl/576
+ // VCRYPTO should be present in POWER8 >= 2.07.
+ // Uses Linux kernel constants from arch/powerpc/include/uapi/asm/cputable.h
+ static const uint32_t kVCRYPTO = 0x02000000;
+ const uint32_t hwcap = GetAuxval(AT_HWCAP2);
+ return (hwcap & kVCRYPTO) != 0;
+
+#elif defined(ABSL_ARCH_ARM)
+ // For ARM: Require crypto+neon
+ // http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0500f/CIHBIBBA.html
+ // Uses Linux kernel constants from arch/arm64/include/asm/hwcap.h
+ static const uint32_t kNEON = 1 << 12;
+ uint32_t hwcap = GetAuxval(AT_HWCAP);
+ if ((hwcap & kNEON) == 0) {
+ return false;
+ }
+
+ // And use it again to detect AES.
+ static const uint32_t kAES = 1 << 0;
+ const uint32_t hwcap2 = GetAuxval(AT_HWCAP2);
+ return (hwcap2 & kAES) != 0;
+
+#elif defined(ABSL_ARCH_AARCH64)
+ // For AARCH64: Require crypto+neon
+ // http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0500f/CIHBIBBA.html
+ static const uint32_t kNEON = 1 << 1;
+ static const uint32_t kAES = 1 << 3;
+ const uint32_t hwcap = GetAuxval(AT_HWCAP);
+ return ((hwcap & kNEON) != 0) && ((hwcap & kAES) != 0);
+#endif
+
+#else // ABSL_INTERNAL_USE_GETAUXVAL
+ // 3. By default, assume that the compiler default.
+ return ABSL_HAVE_ACCELERATED_AES ? true : false;
+
+#endif
+ // NOTE: There are some other techniques that may be worth trying:
+ //
+ // * Use an environment variable: ABSL_RANDOM_USE_HWAES
+ //
+ // * Rely on compiler-generated target-based dispatch.
+ // Using x86/gcc it might look something like this:
+ //
+ // int __attribute__((target("aes"))) HasAes() { return 1; }
+ // int __attribute__((target("default"))) HasAes() { return 0; }
+ //
+ // This does not work on all architecture/compiler combinations.
+ //
+ // * On Linux consider reading /proc/cpuinfo and/or /proc/self/auxv.
+ // These files have lines which are easy to parse; for ARM/AARCH64 it is quite
+ // easy to find the Features: line and extract aes / neon. Likewise for
+ // PPC.
+ //
+ // * Fork a process and test for SIGILL:
+ //
+ // * Many architectures have instructions to read the ISA. Unfortunately
+ // most of those require that the code is running in ring 0 /
+ // protected-mode.
+ //
+ // There are several examples. e.g. Valgrind detects PPC ISA 2.07:
+ // https://github.com/lu-zero/valgrind/blob/master/none/tests/ppc64/test_isa_2_07_part1.c
+ //
+ // MRS <Xt>, ID_AA64ISAR0_EL1 ; Read ID_AA64ISAR0_EL1 into Xt
+ //
+ // uint64_t val;
+ // __asm __volatile("mrs %0, id_aa64isar0_el1" :"=&r" (val));
+ //
+ // * Use a CPUID-style heuristic database.
+ //
+ // * On Apple (__APPLE__), AES is available on Arm v8.
+ // https://stackoverflow.com/questions/45637888/how-to-determine-armv8-features-at-runtime-on-ios
+}
+
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+
+} // namespace random_internal
+} // inline namespace lts_2019_08_08
+} // namespace absl