Export of internal Abseil changes

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0bfa836596a9c787a2f0bdc283011dd1f6810c6e by Benjamin Barenblat <bbaren@google.com>:

Ignore missing CPU frequency on more architectures

Linux on MIPS, PA-RISC, RISC-V, and SystemZ doesn’t expose the nominal
CPU frequency via /sys, so don’t worry if `NominalCPUFrequency` returns
1.0 on those platforms.

Some POWER machines expose the CPU frequency; others do not. Since we
can’t predict which type of machine the tests will run on, simply
disable testing for `NominalCPUFrequency` on POWER.

PiperOrigin-RevId: 347079873

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492b6834ed4a07cbc3abccd846f7e37d8c556ee5 by Benjamin Barenblat <bbaren@google.com>:

Use ABSL_HAVE_THREAD_LOCAL macro instead of copying code

Reduce code duplication by checking the ABSL_HAVE_THREAD_LOCAL macro
instead of copying code from base/config.h.

PiperOrigin-RevId: 347079561

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8d656efce4da9cb032094377e58493d98427a536 by Abseil Team <absl-team@google.com>:

Rollback

PiperOrigin-RevId: 347078779

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221bc69ec6dd7e2777ffcff6942584f979ef6382 by Abseil Team <absl-team@google.com>:

Add flag for 'shallow subcord' feature for experimental ring buffer rollout

There is a potential trade-off of CPU cost vs over-sharing cord data for subcord of large cords. This flag allows making subcords shallow for ringbuffers (with a potential larger waste of referenced source cords), which allows us to make subcord fast for this apps that do no persist (unmodified / plain copied) sub cords.

This change also introduces constants for the default settings, intended to keep the internal cord settings concistent with external flags.

PiperOrigin-RevId: 347053271

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00a56c24293566734009f6bf2169a83fb37a35ba by Abseil Team <absl-team@google.com>:

Revert the usage of variant<> in Cord iterator and reader.

The introduction of the variant may lead to some missed compiler optimizations.

PiperOrigin-RevId: 347053041

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c7b7b5ed7e3ab46b1e75b80f1a7de0bda26c8f70 by Chris Kennelly <ckennelly@google.com>:

Release library for integer power-of-2 functions and bit counting.

PiperOrigin-RevId: 347035065

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5a035c0d9840b251967f9e7039fc6a4e01dd52f3 by Abseil Team <absl-team@google.com>:

Restructure Cord::ChunkIterator for future ring buffer support.

PiperOrigin-RevId: 346890054
GitOrigin-RevId: 0bfa836596a9c787a2f0bdc283011dd1f6810c6e
Change-Id: I3a58e2a44cb4c6f2116c43e2a4ccbc319d3ccecf

1 files changed, 3 insertions, 12 deletions

diff --git a/absl/debugging/internal/stacktrace_config.h b/absl/debugging/internal/stacktrace_config.h
index 90af8528..cca410d4 100644
--- a/absl/debugging/internal/stacktrace_config.h
+++ b/absl/debugging/internal/stacktrace_config.h
@@ -21,6 +21,8 @@
 #ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
 #define ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
 
+#include "absl/base/config.h"
+
 #if defined(ABSL_STACKTRACE_INL_HEADER)
 #error ABSL_STACKTRACE_INL_HEADER cannot be directly set
 
@@ -29,19 +31,8 @@
     "absl/debugging/internal/stacktrace_win32-inl.inc"
 
 #elif defined(__APPLE__)
+#ifdef ABSL_HAVE_THREAD_LOCAL
 // Thread local support required for UnwindImpl.
-// Notes:
-// * Xcode's clang did not support `thread_local` until version 8, and
-//   even then not for all iOS < 9.0.
-// * Xcode 9.3 started disallowing `thread_local` for 32-bit iOS simulator
-//   targeting iOS 9.x.
-// * Xcode 10 moves the deployment target check for iOS < 9.0 to link time
-//   making __has_feature unreliable there.
-//
-// Otherwise, `__has_feature` is only supported by Clang so it has be inside
-// `defined(__APPLE__)` check.
-#if __has_feature(cxx_thread_local) && \
-    !(TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)
 #define ABSL_STACKTRACE_INL_HEADER \
   "absl/debugging/internal/stacktrace_generic-inl.inc"
 #endif