X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FSupport%2FProcess.cpp;h=2c0d37bb32992720ec37892e1415abc4272f9167;hb=55ec2218c448ef9e0d09b5534885b6d2a9786a73;hp=c65cb454046b2c03f5090ed82d02fadaa7309165;hpb=9c69e6ae698f44703725eec8ff27630b6b81f0e3;p=oota-llvm.git

diff --git a/lib/Support/Process.cpp b/lib/Support/Process.cpp
index c65cb454046..2c0d37bb329 100644
--- a/lib/Support/Process.cpp
+++ b/lib/Support/Process.cpp
@@ -11,10 +11,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Support/Process.h"
 #include "llvm/Config/config.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Process.h"
 
-namespace llvm {
+using namespace llvm;
 using namespace sys;
 
 //===----------------------------------------------------------------------===//
@@ -22,17 +23,63 @@ using namespace sys;
 //===          independent code.
 //===----------------------------------------------------------------------===//
 
-unsigned llvm::sys::Process::GetRandomNumber() {
-#if defined(HAVE_ARC4RANDOM)
-  return arc4random();
-#else
-  static int x = (::srand(::time(NULL)), 0);
-  return rand();
+// Empty virtual destructor to anchor the vtable for the process class.
+process::~process() {}
+
+self_process *process::get_self() {
+  // Use a function local static for thread safe initialization and allocate it
+  // as a raw pointer to ensure it is never destroyed.
+  static self_process *SP = new self_process();
+
+  return SP;
+}
+
+#if defined(_MSC_VER)
+// Visual Studio complains that the self_process destructor never exits. This
+// doesn't make much sense, as that's the whole point of calling abort... Just
+// silence this warning.
+#pragma warning(push)
+#pragma warning(disable:4722)
 #endif
+
+// The destructor for the self_process subclass must never actually be
+// executed. There should be at most one instance of this class, and that
+// instance should live until the process terminates to avoid the potential for
+// racy accesses during shutdown.
+self_process::~self_process() {
+  llvm_unreachable("This destructor must never be executed!");
 }
 
+/// \brief A helper function to compute the elapsed wall-time since the program
+/// started.
+///
+/// Note that this routine actually computes the elapsed wall time since the
+/// first time it was called. However, we arrange to have it called during the
+/// startup of the process to get approximately correct results.
+static TimeValue getElapsedWallTime() {
+  static TimeValue &StartTime = *new TimeValue(TimeValue::now());
+  return TimeValue::now() - StartTime;
 }
 
+/// \brief A special global variable to ensure we call \c getElapsedWallTime
+/// during global initialization of the program.
+///
+/// Note that this variable is never referenced elsewhere. Doing so could
+/// create race conditions during program startup or shutdown.
+static volatile TimeValue DummyTimeValue = getElapsedWallTime();
+
+// Implement this routine by using the static helpers above. They're already
+// portable.
+TimeValue self_process::get_wall_time() const {
+  return getElapsedWallTime();
+}
+
+
+#if defined(_MSC_VER)
+#pragma warning(pop)
+#endif
+
+
 // Include the platform-specific parts of this class.
 #ifdef LLVM_ON_UNIX
 #include "Unix/Process.inc"