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authorGravatar Abseil Team <absl-team@google.com>2019-11-13 08:54:32 -0800
committerGravatar Andy Getz <durandal@google.com>2019-11-13 15:04:44 -0500
commitfa8c75182fbfdeddb2485fc0d53baeda3f40b7a3 (patch)
treecf973bc4dee81f08cb7edd811353d944d10fc5f9 /absl/base
parent85092b4b648ca729c6263c4a302a41dfff28705e (diff)
Export of internal Abseil changes
-- 049ac45508e335c6f010f2d28d71016b9fa65b4e by Derek Mauro <dmauro@google.com>: Fix librt detection PiperOrigin-RevId: 280207723 -- 6382c3a9fb2643af9dc031f92ca846c4a78e249c by Andy Getzendanner <durandal@google.com>: Fix Conan builds Import of https://github.com/abseil/abseil-cpp/pull/400 PiperOrigin-RevId: 280025424 -- aebcd52b1686ac82663a8d0193b60d0122a43372 by Samuel Benzaquen <sbenza@google.com>: Enable the assertion in the iterator's operator== and operator!= PiperOrigin-RevId: 279998951 -- 5b61d909e2159ac6fd45e0e456818db1e725ecd1 by Derek Mauro <dmauro@google.com>: Add best effort support for compiling much of Abseil with MinGW. This involves disabling ABSL_ATTRIBUTE_WEAK and adding link flags. A change to CCTZ is still necessary. Tests were not run yet, but most of them now build. PiperOrigin-RevId: 279966541 -- 4336f8b10cff906e2defdd7d1d449cde4907da5d by Abseil Team <absl-team@google.com>: Add comments and relax memory orders in base_internal::CallOnceImpl. Add a comment to document the memory order guarantee if base_internal::SpinLockWait() is called and returns kOnceDone. Add a comment for the load/store sequence in base_internal::CallOnceImpl based on Mike Burrows' explanation. The atomic load of 'control' in the #ifndef NDEBUG block does not need std::memory_order_acquire. It can use std::memory_order_relaxed. The atomic compare_exchange_strong of 'control' does not need std::memory_order_acquire in the success case. It can use std::memory_order_relaxed. PiperOrigin-RevId: 279814155 -- 407de3a5e9af957cded54a136ca0468bde620d4d by Abseil Team <absl-team@google.com>: Added a script to generate abseil.podspec from all BUILD.bazel files automatically. PiperOrigin-RevId: 279811441 -- 26139497d4a363d6c7bc989c554da593e8819a07 by Derek Mauro <dmauro@google.com>: Add missing copyright and Apache License to //absl/functional/BUILD.bazel PiperOrigin-RevId: 279795227 -- 98ed625b02af6e5834edf52a920d8ca2dab4cd90 by Matt Kulukundis <kfm@google.com>: Switch the implementation of hashtablez to *only* work on platforms that have a PER_THREAD_TLS. The old case is very slow (global mutex) and nobody collects data from that configuration anyway. PiperOrigin-RevId: 279775149 -- 07225900ef672c005c38f467ad3f92f38d0922b3 by Derek Mauro <dmauro@google.com>: Remove the minumum glibc version check PiperOrigin-RevId: 279750412 -- ec09956a951b4f52228ecc81968b8db7ae19ed15 by Derek Mauro <dmauro@google.com>: CMake only: link with -lrt to support older glibc versions PiperOrigin-RevId: 279741661 -- 97b113fb2e8246f6152c36330ba13793b37154b6 by Xiaoyi Zhang <zhangxy@google.com>: Internal change. PiperOrigin-RevId: 279390188 -- ca8f72f2721546cc9b01bd01b2ea144962e6e0c5 by Andy Getzendanner <durandal@google.com>: Expose PutTwoDigits for internal use within Abseil. PiperOrigin-RevId: 279374239 -- 14c6384cc03bbdfdefd2e4b635f104af5dd7e026 by Derek Mauro <dmauro@google.com>: Remove log_severity sources from the base target. They are already compiled as part of a separate library. PiperOrigin-RevId: 279372619 -- 3c5d926c718f8bf394e3bee87b6ba8d94601e0d3 by Abseil Team <absl-team@google.com>: s/indepdent/independent/g in SimpleAtof's documentation. PiperOrigin-RevId: 279350836 -- de2c44be8a8edf9efa1fe2007cba3564f3e5b0b8 by Abseil Team <absl-team@google.com>: Internal change PiperOrigin-RevId: 279346990 -- 2ba078341423fcf6d0ba5ca1831f86570a26e615 by Samuel Benzaquen <sbenza@google.com>: Add hash support for std::wstring, std::u16string and std::u32string. PiperOrigin-RevId: 279320672 -- 3272d3ffcfa55283a04f90e5868701912da95ef7 by Andy Soffer <asoffer@google.com>: Removing a bunch of __restricts that amount to no performance differences. One of these is the cause of https://github.com/abseil/abseil-cpp/issues/396. In particular, in one of the Vector128Store functions, restricts on two pointers that were indeed aliased seems to be the root cause of the issues. Closes #396 PiperOrigin-RevId: 279318999 -- 342f338ab31cc24344d5de8f28cf455bbb629a17 by Jorg Brown <jorg@google.com>: Support uint128 in SimpleAtoi PiperOrigin-RevId: 279234038 -- 81cb0a04cf2dc4515d303679fc60968712191571 by Derek Mauro <dmauro@google.com>: Change the check for futex availability to support older Linux systems PiperOrigin-RevId: 279147079 -- cb4ca4aa4c8d2d710a5d483c56c4ce4f979e14b1 by Abseil Team <absl-team@google.com>: Add IWYU pragma: export for int128 .inc files. PiperOrigin-RevId: 279107098 -- b8df86ef610c366729f07326c726f3e34817b4dd by Abseil Team <absl-team@google.com>: An optimization for Waiter::Post() in the SEM waiter mode. Like the FUTEX waiter mode, Waiter::Post() only needs to call Poke() if it incremented the atomic variable from 0. PiperOrigin-RevId: 279086133 GitOrigin-RevId: 049ac45508e335c6f010f2d28d71016b9fa65b4e Change-Id: I4c1a4073fff62cb6a1fcb1c104aa7d62dad588c2
Diffstat (limited to 'absl/base')
-rw-r--r--absl/base/BUILD.bazel4
-rw-r--r--absl/base/CMakeLists.txt8
-rw-r--r--absl/base/attributes.h6
-rw-r--r--absl/base/call_once.h13
-rw-r--r--absl/base/policy_checks.h10
5 files changed, 24 insertions, 17 deletions
diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index 6fc712d9..7e234bc6 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -192,7 +192,9 @@ cc_library(
],
copts = ABSL_DEFAULT_COPTS,
linkopts = select({
- "//absl:windows": [],
+ "//absl:windows": [
+ "-DEFAULTLIB:shlwapi.lib",
+ ],
"//conditions:default": ["-pthread"],
}) + ABSL_DEFAULT_LINKOPTS,
deps = [
diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt
index 9550cdb2..7ab6955e 100644
--- a/absl/base/CMakeLists.txt
+++ b/absl/base/CMakeLists.txt
@@ -14,6 +14,8 @@
# limitations under the License.
#
+find_library(LIBRT rt)
+
absl_cc_library(
NAME
atomic_hook
@@ -163,16 +165,18 @@ absl_cc_library(
"internal/thread_identity.h"
"internal/tsan_mutex_interface.h"
"internal/unscaledcycleclock.h"
- "log_severity.h"
SRCS
"internal/cycleclock.cc"
"internal/spinlock.cc"
"internal/sysinfo.cc"
"internal/thread_identity.cc"
"internal/unscaledcycleclock.cc"
- "log_severity.cc"
COPTS
${ABSL_DEFAULT_COPTS}
+ LINKOPTS
+ ${ABSL_DEFAULT_LINKOPTS}
+ $<$<BOOL:${LIBRT}>:${LIBRT}>
+ $<$<BOOL:${MINGW}>:"shlwapi">
DEPS
absl::atomic_hook
absl::base_internal
diff --git a/absl/base/attributes.h b/absl/base/attributes.h
index 7b7656a8..acd1c526 100644
--- a/absl/base/attributes.h
+++ b/absl/base/attributes.h
@@ -158,9 +158,11 @@
// Weak attributes currently do not work properly in LLVM's Windows backend,
// so disable them there. See https://bugs.llvm.org/show_bug.cgi?id=37598
// for further information.
-#if (ABSL_HAVE_ATTRIBUTE(weak) || \
+// The MinGW compiler doesn't complain about the weak attribute until the link
+// step, presumably because Windows doesn't use ELF binaries.
+#if (ABSL_HAVE_ATTRIBUTE(weak) || \
(defined(__GNUC__) && !defined(__clang__))) && \
- !(defined(__llvm__) && defined(_WIN32))
+ !(defined(__llvm__) && defined(_WIN32)) && !defined(__MINGW32__)
#undef ABSL_ATTRIBUTE_WEAK
#define ABSL_ATTRIBUTE_WEAK __attribute__((weak))
#define ABSL_HAVE_ATTRIBUTE_WEAK 1
diff --git a/absl/base/call_once.h b/absl/base/call_once.h
index 4aa6360c..e1614e51 100644
--- a/absl/base/call_once.h
+++ b/absl/base/call_once.h
@@ -148,7 +148,7 @@ void CallOnceImpl(std::atomic<uint32_t>* control,
Args&&... args) {
#ifndef NDEBUG
{
- uint32_t old_control = control->load(std::memory_order_acquire);
+ uint32_t old_control = control->load(std::memory_order_relaxed);
if (old_control != kOnceInit &&
old_control != kOnceRunning &&
old_control != kOnceWaiter &&
@@ -166,14 +166,23 @@ void CallOnceImpl(std::atomic<uint32_t>* control,
// Must do this before potentially modifying control word's state.
base_internal::SchedulingHelper maybe_disable_scheduling(scheduling_mode);
// Short circuit the simplest case to avoid procedure call overhead.
+ // The base_internal::SpinLockWait() call returns either kOnceInit or
+ // kOnceDone. If it returns kOnceDone, it must have loaded the control word
+ // with std::memory_order_acquire and seen a value of kOnceDone.
uint32_t old_control = kOnceInit;
if (control->compare_exchange_strong(old_control, kOnceRunning,
- std::memory_order_acquire,
std::memory_order_relaxed) ||
base_internal::SpinLockWait(control, ABSL_ARRAYSIZE(trans), trans,
scheduling_mode) == kOnceInit) {
base_internal::Invoke(std::forward<Callable>(fn),
std::forward<Args>(args)...);
+ // The call to SpinLockWake below is an optimization, because the waiter
+ // in SpinLockWait is waiting with a short timeout. The atomic load/store
+ // sequence is slightly faster than an atomic exchange:
+ // old_control = control->exchange(base_internal::kOnceDone,
+ // std::memory_order_release);
+ // We opt for a slightly faster case when there are no waiters, in spite
+ // of longer tail latency when there are waiters.
old_control = control->load(std::memory_order_relaxed);
control->store(base_internal::kOnceDone, std::memory_order_release);
if (old_control == base_internal::kOnceWaiter) {
diff --git a/absl/base/policy_checks.h b/absl/base/policy_checks.h
index 699fb1a2..4dfa49e5 100644
--- a/absl/base/policy_checks.h
+++ b/absl/base/policy_checks.h
@@ -82,16 +82,6 @@
// Standard Library Check
// -----------------------------------------------------------------------------
-// We have chosen glibc 2.12 as the minimum as it was tagged for release
-// in May, 2010 and includes some functionality used in Google software
-// (for instance pthread_setname_np):
-// https://sourceware.org/ml/libc-alpha/2010-05/msg00000.html
-#if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
-#if !__GLIBC_PREREQ(2, 12)
-#error "Minimum required version of glibc is 2.12."
-#endif
-#endif
-
#if defined(_STLPORT_VERSION)
#error "STLPort is not supported."
#endif