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https://github.com/c64scene-ar/llvm-6502.git
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529e9d307e
This patch removes the functions llvm_start_multithreaded() and llvm_stop_multithreaded(), and changes llvm_is_multithreaded() to return a constant value based on the value of the compile-time definition LLVM_ENABLE_THREADS. Previously, it was possible to have compile-time support for threads on, and runtime support for threads off, in which case certain mutexes were not allocated or ever acquired. Now, if the build is created with threads enabled, mutexes are always acquired. A test before/after patch of compiling a very large TU showed no noticeable performance impact of this change. Reviewers: rnk Differential Revision: http://reviews.llvm.org/D4076 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210600 91177308-0d34-0410-b5e6-96231b3b80d8
112 lines
3.3 KiB
C++
112 lines
3.3 KiB
C++
//===-- llvm/Support/ManagedStatic.h - Static Global wrapper ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the ManagedStatic class and the llvm_shutdown() function.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_MANAGED_STATIC_H
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#define LLVM_SUPPORT_MANAGED_STATIC_H
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#include "llvm/Support/Atomic.h"
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#include "llvm/Support/Threading.h"
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#include "llvm/Support/Valgrind.h"
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namespace llvm {
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/// object_creator - Helper method for ManagedStatic.
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template<class C>
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void* object_creator() {
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return new C();
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}
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/// object_deleter - Helper method for ManagedStatic.
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///
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template<typename T> struct object_deleter {
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static void call(void * Ptr) { delete (T*)Ptr; }
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};
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template<typename T, size_t N> struct object_deleter<T[N]> {
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static void call(void * Ptr) { delete[] (T*)Ptr; }
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};
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/// ManagedStaticBase - Common base class for ManagedStatic instances.
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class ManagedStaticBase {
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protected:
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// This should only be used as a static variable, which guarantees that this
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// will be zero initialized.
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mutable void *Ptr;
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mutable void (*DeleterFn)(void*);
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mutable const ManagedStaticBase *Next;
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void RegisterManagedStatic(void *(*creator)(), void (*deleter)(void*)) const;
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public:
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/// isConstructed - Return true if this object has not been created yet.
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bool isConstructed() const { return Ptr != nullptr; }
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void destroy() const;
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};
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/// ManagedStatic - This transparently changes the behavior of global statics to
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/// be lazily constructed on demand (good for reducing startup times of dynamic
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/// libraries that link in LLVM components) and for making destruction be
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/// explicit through the llvm_shutdown() function call.
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///
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template<class C>
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class ManagedStatic : public ManagedStaticBase {
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public:
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// Accessors.
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C &operator*() {
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void* tmp = Ptr;
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if (llvm_is_multithreaded()) sys::MemoryFence();
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if (!tmp) RegisterManagedStatic(object_creator<C>, object_deleter<C>::call);
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TsanHappensAfter(this);
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return *static_cast<C*>(Ptr);
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}
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C *operator->() {
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void* tmp = Ptr;
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if (llvm_is_multithreaded()) sys::MemoryFence();
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if (!tmp) RegisterManagedStatic(object_creator<C>, object_deleter<C>::call);
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TsanHappensAfter(this);
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return static_cast<C*>(Ptr);
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}
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const C &operator*() const {
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void* tmp = Ptr;
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if (llvm_is_multithreaded()) sys::MemoryFence();
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if (!tmp) RegisterManagedStatic(object_creator<C>, object_deleter<C>::call);
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TsanHappensAfter(this);
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return *static_cast<C*>(Ptr);
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}
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const C *operator->() const {
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void* tmp = Ptr;
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if (llvm_is_multithreaded()) sys::MemoryFence();
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if (!tmp) RegisterManagedStatic(object_creator<C>, object_deleter<C>::call);
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TsanHappensAfter(this);
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return static_cast<C*>(Ptr);
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}
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};
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/// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
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void llvm_shutdown();
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/// llvm_shutdown_obj - This is a simple helper class that calls
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/// llvm_shutdown() when it is destroyed.
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struct llvm_shutdown_obj {
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llvm_shutdown_obj() { }
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~llvm_shutdown_obj() { llvm_shutdown(); }
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};
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}
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#endif
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