Add Chrono.h - std::chrono support header

Summary:
std::chrono mostly covers the functionality of llvm::sys::TimeValue and
lldb_private::TimeValue. This header adds a bit of utility functions and
typedefs, which make the usage of the library and porting code from TimeValues
easier.

Rationale:
- TimePoint typedef - precision of system_clock is implementation defined -
  using a well-defined precision helps maintain consistency between platforms,
  makes it interact better with existing TimeValue classes, and avoids cases
  there a time point is implicitly convertible to a specific precision on some
  platforms but not on others.
- system_clock::to_time_t only accepts time_points with the default system
  precision (even though time_t has only second precision on all platforms we
  support). To avoid the need for explicit casts, I have added a toTimeT()
  wrapper function. toTimePoint(time_t) was not strictly necessary, but I have
  added it for symmetry.

Reviewers: zturner, mehdi_amini

Subscribers: beanz, mgorny, llvm-commits, modocache

Differential Revision: https://reviews.llvm.org/D25416

llvm-svn: 284590

1 files changed, 8 insertions, 9 deletions

diff --git a/llvm/lib/Support/TimeValue.cpp b/llvm/lib/Support/TimeValue.cpp
index 94a4c011693..18c84ca9fa0 100644
--- a/llvm/lib/Support/TimeValue.cpp
+++ b/llvm/lib/Support/TimeValue.cpp
@@ -12,7 +12,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/TimeValue.h"
-#include "llvm/Config/config.h"
+#include "llvm/Support/Chrono.h"
+#include "llvm/Support/ScopedPrinter.h"
 
 namespace llvm {
 
@@ -45,12 +46,10 @@ void TimeValue::normalize() {
   }
 }
 
-} // namespace llvm
+std::string TimeValue::str() const { return to_string(TimePoint<>(*this)); }
+
+TimeValue TimeValue::now() {
+  return TimePoint<>(std::chrono::system_clock::now());
+}
 
-/// Include the platform-specific portion of TimeValue class
-#ifdef LLVM_ON_UNIX
-#include "Unix/TimeValue.inc"
-#endif
-#ifdef LLVM_ON_WIN32
-#include "Windows/TimeValue.inc"
-#endif
+} // namespace llvm