1 //===-- Process.cpp - Implement OS Process Concept --------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This header file implements the operating system Process concept. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/Config/config.h" 15 #include "llvm/Support/ErrorHandling.h" 16 #include "llvm/Support/Process.h" 17 18 using namespace llvm; 19 using namespace sys; 20 21 //===----------------------------------------------------------------------===// 22 //=== WARNING: Implementation here must contain only TRULY operating system 23 //=== independent code. 24 //===----------------------------------------------------------------------===// 25 26 // Empty virtual destructor to anchor the vtable for the process class. 27 process::~process() {} 28 29 self_process *process::get_self() { 30 // Use a function local static for thread safe initialization and allocate it 31 // as a raw pointer to ensure it is never destroyed. 32 static self_process *SP = new self_process(); 33 34 return SP; 35 } 36 37 #if defined(_MSC_VER) 38 // Visual Studio complains that the self_process destructor never exits. This 39 // doesn't make much sense, as that's the whole point of calling abort... Just 40 // silence this warning. 41 #pragma warning(push) 42 #pragma warning(disable:4722) 43 #endif 44 45 // The destructor for the self_process subclass must never actually be 46 // executed. There should be at most one instance of this class, and that 47 // instance should live until the process terminates to avoid the potential for 48 // racy accesses during shutdown. 49 self_process::~self_process() { 50 llvm_unreachable("This destructor must never be executed!"); 51 } 52 53 /// \brief A helper function to compute the elapsed wall-time since the program 54 /// started. 55 /// 56 /// Note that this routine actually computes the elapsed wall time since the 57 /// first time it was called. However, we arrange to have it called during the 58 /// startup of the process to get approximately correct results. 59 static TimeValue getElapsedWallTime() { 60 static TimeValue &StartTime = *new TimeValue(TimeValue::now()); 61 return TimeValue::now() - StartTime; 62 } 63 64 /// \brief A special global variable to ensure we call \c getElapsedWallTime 65 /// during global initialization of the program. 66 /// 67 /// Note that this variable is never referenced elsewhere. Doing so could 68 /// create race conditions during program startup or shutdown. 69 static volatile TimeValue DummyTimeValue = getElapsedWallTime(); 70 71 // Implement this routine by using the static helpers above. They're already 72 // portable. 73 TimeValue self_process::get_wall_time() const { 74 return getElapsedWallTime(); 75 } 76 77 78 #if defined(_MSC_VER) 79 #pragma warning(pop) 80 #endif 81 82 83 // Include the platform-specific parts of this class. 84 #ifdef LLVM_ON_UNIX 85 #include "Unix/Process.inc" 86 #endif 87 #ifdef LLVM_ON_WIN32 88 #include "Windows/Process.inc" 89 #endif 90
