From 4721e55a0c2e749cba4f91aa584508284ff67d2c Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Mon, 3 Mar 2014 17:53:30 +0000 Subject: [PATCH] [C++11] Replace LLVM atomics with std::atomic. With C++11 we finally have a standardized way to specify atomic operations. Use them to replace the existing custom implemention. Sadly the translation is not entirely trivial as std::atomic allows more fine-grained control over the atomicity. I tried to preserve the old semantics as well as possible. Differential Revision: http://llvm-reviews.chandlerc.com/D2915 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202730 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/ADT/Statistic.h | 36 ++++++++++++++++------------ include/llvm/PassSupport.h | 18 +++++++------- include/llvm/Support/ManagedStatic.h | 14 +++++++---- lib/IR/Attributes.cpp | 1 - lib/IR/DiagnosticInfo.cpp | 6 ++--- lib/Support/ManagedStatic.cpp | 3 +-- lib/Support/Statistic.cpp | 2 +- lib/Support/Threading.cpp | 6 ++--- lib/Support/Timer.cpp | 4 ++-- 9 files changed, 49 insertions(+), 41 deletions(-) diff --git a/include/llvm/ADT/Statistic.h b/include/llvm/ADT/Statistic.h index 26aac7bea62..5e7a433e441 100644 --- a/include/llvm/ADT/Statistic.h +++ b/include/llvm/ADT/Statistic.h @@ -26,8 +26,8 @@ #ifndef LLVM_ADT_STATISTIC_H #define LLVM_ADT_STATISTIC_H -#include "llvm/Support/Atomic.h" #include "llvm/Support/Valgrind.h" +#include namespace llvm { class raw_ostream; @@ -36,10 +36,10 @@ class Statistic { public: const char *Name; const char *Desc; - volatile llvm::sys::cas_flag Value; + std::atomic Value; bool Initialized; - llvm::sys::cas_flag getValue() const { return Value; } + unsigned getValue() const { return Value; } const char *getName() const { return Name; } const char *getDesc() const { return Desc; } @@ -63,48 +63,54 @@ public: // atomic operation to update the value safely in the presence of // concurrent accesses, but not to read the return value, so the // return value is not thread safe. - sys::AtomicIncrement(&Value); + ++Value; return init(); } unsigned operator++(int) { init(); - unsigned OldValue = Value; - sys::AtomicIncrement(&Value); + unsigned OldValue = Value++; return OldValue; } const Statistic &operator--() { - sys::AtomicDecrement(&Value); + --Value; return init(); } unsigned operator--(int) { init(); - unsigned OldValue = Value; - sys::AtomicDecrement(&Value); + unsigned OldValue = Value--; return OldValue; } const Statistic &operator+=(const unsigned &V) { if (!V) return *this; - sys::AtomicAdd(&Value, V); + Value += V; return init(); } const Statistic &operator-=(const unsigned &V) { if (!V) return *this; - sys::AtomicAdd(&Value, -V); + Value -= V; return init(); } const Statistic &operator*=(const unsigned &V) { - sys::AtomicMul(&Value, V); + unsigned Original, Result; + do { + Original = Value; + Result = Original * V; + } while (!Value.compare_exchange_strong(Original, Result)); return init(); } const Statistic &operator/=(const unsigned &V) { - sys::AtomicDiv(&Value, V); + unsigned Original, Result; + do { + Original = Value; + Result = Original / V; + } while (!Value.compare_exchange_strong(Original, Result)); return init(); } @@ -151,7 +157,7 @@ public: protected: Statistic &init() { bool tmp = Initialized; - sys::MemoryFence(); + std::atomic_thread_fence(std::memory_order_seq_cst); if (!tmp) RegisterStatistic(); TsanHappensAfter(this); return *this; @@ -162,7 +168,7 @@ protected: // STATISTIC - A macro to make definition of statistics really simple. This // automatically passes the DEBUG_TYPE of the file into the statistic. #define STATISTIC(VARNAME, DESC) \ - static llvm::Statistic VARNAME = { DEBUG_TYPE, DESC, 0, 0 } + static llvm::Statistic VARNAME = { DEBUG_TYPE, DESC, {}, 0 } /// \brief Enable the collection and printing of statistics. void EnableStatistics(); diff --git a/include/llvm/PassSupport.h b/include/llvm/PassSupport.h index baee77f1338..c746506f473 100644 --- a/include/llvm/PassSupport.h +++ b/include/llvm/PassSupport.h @@ -24,8 +24,8 @@ #include "Pass.h" #include "llvm/InitializePasses.h" #include "llvm/PassRegistry.h" -#include "llvm/Support/Atomic.h" #include "llvm/Support/Valgrind.h" +#include #include namespace llvm { @@ -147,21 +147,21 @@ private: }; #define CALL_ONCE_INITIALIZATION(function) \ - static volatile sys::cas_flag initialized = 0; \ - sys::cas_flag old_val = sys::CompareAndSwap(&initialized, 1, 0); \ - if (old_val == 0) { \ + static std::atomic initialized; \ + int old_val = 0; \ + if (initialized.compare_exchange_strong(old_val, 1)) { \ function(Registry); \ - sys::MemoryFence(); \ + std::atomic_thread_fence(std::memory_order_seq_cst); \ TsanIgnoreWritesBegin(); \ TsanHappensBefore(&initialized); \ initialized = 2; \ TsanIgnoreWritesEnd(); \ } else { \ - sys::cas_flag tmp = initialized; \ - sys::MemoryFence(); \ + int tmp = initialized.load(); \ + std::atomic_thread_fence(std::memory_order_seq_cst); \ while (tmp != 2) { \ - tmp = initialized; \ - sys::MemoryFence(); \ + tmp = initialized.load(); \ + std::atomic_thread_fence(std::memory_order_seq_cst); \ } \ } \ TsanHappensAfter(&initialized); diff --git a/include/llvm/Support/ManagedStatic.h b/include/llvm/Support/ManagedStatic.h index 5587618d11b..4a12a1ba8e7 100644 --- a/include/llvm/Support/ManagedStatic.h +++ b/include/llvm/Support/ManagedStatic.h @@ -14,9 +14,9 @@ #ifndef LLVM_SUPPORT_MANAGED_STATIC_H #define LLVM_SUPPORT_MANAGED_STATIC_H -#include "llvm/Support/Atomic.h" #include "llvm/Support/Threading.h" #include "llvm/Support/Valgrind.h" +#include namespace llvm { @@ -64,7 +64,8 @@ public: // Accessors. C &operator*() { void* tmp = Ptr; - if (llvm_is_multithreaded()) sys::MemoryFence(); + if (llvm_is_multithreaded()) + std::atomic_thread_fence(std::memory_order_seq_cst); if (!tmp) RegisterManagedStatic(object_creator, object_deleter::call); TsanHappensAfter(this); @@ -72,7 +73,8 @@ public: } C *operator->() { void* tmp = Ptr; - if (llvm_is_multithreaded()) sys::MemoryFence(); + if (llvm_is_multithreaded()) + std::atomic_thread_fence(std::memory_order_seq_cst); if (!tmp) RegisterManagedStatic(object_creator, object_deleter::call); TsanHappensAfter(this); @@ -80,7 +82,8 @@ public: } const C &operator*() const { void* tmp = Ptr; - if (llvm_is_multithreaded()) sys::MemoryFence(); + if (llvm_is_multithreaded()) + std::atomic_thread_fence(std::memory_order_seq_cst); if (!tmp) RegisterManagedStatic(object_creator, object_deleter::call); TsanHappensAfter(this); @@ -88,7 +91,8 @@ public: } const C *operator->() const { void* tmp = Ptr; - if (llvm_is_multithreaded()) sys::MemoryFence(); + if (llvm_is_multithreaded()) + std::atomic_thread_fence(std::memory_order_seq_cst); if (!tmp) RegisterManagedStatic(object_creator, object_deleter::call); TsanHappensAfter(this); diff --git a/lib/IR/Attributes.cpp b/lib/IR/Attributes.cpp index 9d9d948527c..24cd6c7c1a2 100644 --- a/lib/IR/Attributes.cpp +++ b/lib/IR/Attributes.cpp @@ -18,7 +18,6 @@ #include "LLVMContextImpl.h" #include "llvm/ADT/StringExtras.h" #include "llvm/IR/Type.h" -#include "llvm/Support/Atomic.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ManagedStatic.h" #include "llvm/Support/Mutex.h" diff --git a/lib/IR/DiagnosticInfo.cpp b/lib/IR/DiagnosticInfo.cpp index 86e8788eb09..75ddd94b354 100644 --- a/lib/IR/DiagnosticInfo.cpp +++ b/lib/IR/DiagnosticInfo.cpp @@ -19,14 +19,14 @@ #include "llvm/IR/Function.h" #include "llvm/IR/Instruction.h" #include "llvm/IR/Metadata.h" -#include "llvm/Support/Atomic.h" +#include #include using namespace llvm; int llvm::getNextAvailablePluginDiagnosticKind() { - static sys::cas_flag PluginKindID = DK_FirstPluginKind; - return (int)sys::AtomicIncrement(&PluginKindID); + static std::atomic PluginKindID(DK_FirstPluginKind); + return ++PluginKindID; } DiagnosticInfoInlineAsm::DiagnosticInfoInlineAsm(const Instruction &I, diff --git a/lib/Support/ManagedStatic.cpp b/lib/Support/ManagedStatic.cpp index 098cccb68df..c19f8cb4859 100644 --- a/lib/Support/ManagedStatic.cpp +++ b/lib/Support/ManagedStatic.cpp @@ -13,7 +13,6 @@ #include "llvm/Support/ManagedStatic.h" #include "llvm/Config/config.h" -#include "llvm/Support/Atomic.h" #include using namespace llvm; @@ -28,7 +27,7 @@ void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(), void* tmp = Creator ? Creator() : 0; TsanHappensBefore(this); - sys::MemoryFence(); + std::atomic_thread_fence(std::memory_order_seq_cst); // This write is racy against the first read in the ManagedStatic // accessors. The race is benign because it does a second read after a diff --git a/lib/Support/Statistic.cpp b/lib/Support/Statistic.cpp index 56c3b0f5659..9d075736b30 100644 --- a/lib/Support/Statistic.cpp +++ b/lib/Support/Statistic.cpp @@ -76,7 +76,7 @@ void Statistic::RegisterStatistic() { StatInfo->addStatistic(this); TsanHappensBefore(this); - sys::MemoryFence(); + std::atomic_thread_fence(std::memory_order_seq_cst); // Remember we have been registered. TsanIgnoreWritesBegin(); Initialized = true; diff --git a/lib/Support/Threading.cpp b/lib/Support/Threading.cpp index 9d7ac6c18de..15dd8a98052 100644 --- a/lib/Support/Threading.cpp +++ b/lib/Support/Threading.cpp @@ -13,8 +13,8 @@ #include "llvm/Support/Threading.h" #include "llvm/Config/config.h" -#include "llvm/Support/Atomic.h" #include "llvm/Support/Mutex.h" +#include #include using namespace llvm; @@ -31,7 +31,7 @@ bool llvm::llvm_start_multithreaded() { // We fence here to ensure that all initialization is complete BEFORE we // return from llvm_start_multithreaded(). - sys::MemoryFence(); + std::atomic_thread_fence(std::memory_order_seq_cst); return true; #else return false; @@ -44,7 +44,7 @@ void llvm::llvm_stop_multithreaded() { // We fence here to insure that all threaded operations are complete BEFORE we // return from llvm_stop_multithreaded(). - sys::MemoryFence(); + std::atomic_thread_fence(std::memory_order_seq_cst); multithreaded_mode = false; delete global_lock; diff --git a/lib/Support/Timer.cpp b/lib/Support/Timer.cpp index 0456f5d6383..03845f21f2d 100644 --- a/lib/Support/Timer.cpp +++ b/lib/Support/Timer.cpp @@ -81,14 +81,14 @@ raw_ostream *llvm::CreateInfoOutputFile() { static TimerGroup *DefaultTimerGroup = 0; static TimerGroup *getDefaultTimerGroup() { TimerGroup *tmp = DefaultTimerGroup; - sys::MemoryFence(); + std::atomic_thread_fence(std::memory_order_seq_cst); if (tmp) return tmp; llvm_acquire_global_lock(); tmp = DefaultTimerGroup; if (!tmp) { tmp = new TimerGroup("Miscellaneous Ungrouped Timers"); - sys::MemoryFence(); + std::atomic_thread_fence(std::memory_order_seq_cst); DefaultTimerGroup = tmp; } llvm_release_global_lock();