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https://github.com/c64scene-ar/llvm-6502.git
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5f00b0c5b6
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71819 91177308-0d34-0410-b5e6-96231b3b80d8
129 lines
3.4 KiB
C++
129 lines
3.4 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/System/Atomic.h"
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namespace llvm {
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/// object_deleter - Helper method for ManagedStatic.
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///
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template<class C>
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void object_deleter(void *Ptr) {
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delete (C*)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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mutable sys::cas_flag InitFlag;
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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 *ObjPtr, 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 != 0; }
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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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sys::cas_flag OldFlag = sys::CompareAndSwap(&InitFlag, 1, 0);
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if (OldFlag == 0) {
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LazyInit();
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sys::MemoryFence();
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InitFlag = 2;
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} else if (OldFlag == 1)
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while (OldFlag == 1) ;
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return *static_cast<C*>(Ptr);
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}
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C *operator->() {
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sys::cas_flag OldFlag = sys::CompareAndSwap(&InitFlag, 1, 0);
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if (OldFlag == 0) {
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LazyInit();
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sys::MemoryFence();
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InitFlag = 2;
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} else if (OldFlag == 1)
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while (OldFlag == 1) ;
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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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sys::cas_flag OldFlag = sys::CompareAndSwap(&InitFlag, 1, 0);
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if (OldFlag == 0) {
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LazyInit();
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sys::MemoryFence();
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InitFlag = 2;
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} else if (OldFlag == 1)
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while (OldFlag == 1) ;
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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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sys::cas_flag OldFlag = sys::CompareAndSwap(&InitFlag, 1, 0);
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if (OldFlag == 0) {
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LazyInit();
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sys::MemoryFence();
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InitFlag = 2;
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} else if (OldFlag == 1)
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while (OldFlag == 1) ;
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return static_cast<C*>(Ptr);
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}
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public:
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void LazyInit() const {
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RegisterManagedStatic(new C(), object_deleter<C>);
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}
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};
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template<void (*CleanupFn)(void*)>
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class ManagedCleanup : public ManagedStaticBase {
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public:
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void Register() { RegisterManagedStatic(0, CleanupFn); }
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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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