1 //===-- Process.cpp - Implement OS Process Concept --------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This header file implements the operating system Process concept.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Config/config.h"
15 #include "llvm/Support/ErrorHandling.h"
16 #include "llvm/Support/Process.h"
21 //===----------------------------------------------------------------------===//
22 //=== WARNING: Implementation here must contain only TRULY operating system
23 //=== independent code.
24 //===----------------------------------------------------------------------===//
26 // Empty virtual destructor to anchor the vtable for the process class.
27 process::~process() {}
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();
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.
42 #pragma warning(disable:4722)
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!");
53 /// \brief A helper function to compute the elapsed wall-time since the program
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;
64 /// \brief A special global variable to ensure we call \c getElapsedWallTime
65 /// during global initialization of the program.
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();
71 // Implement this routine by using the static helpers above. They're already
73 TimeValue self_process::get_wall_time() const {
74 return getElapsedWallTime();
83 // Include the platform-specific parts of this class.
85 #include "Unix/Process.inc"
88 #include "Windows/Process.inc"