commit 6bc28c4a1be98f81739399fa71544fd0c7c8a704
author Scott Todd <scotttodd@google.com> Mon Aug 10 10:06:54 2020 -0700
committer GitHub <noreply@github.com> Mon Aug 10 10:06:54 2020 -0700
tree c0945e0b0b6f7cc9b50a0890a055ddc51d0037b3
parent 7779a034320038778730796b2529601b915fe91e

Use platform-specific, hopefully higher precision, system time. (#2823)

Fixes https://github.com/google/iree/issues/2801

iree/base/BUILD

diff --git a/iree/base/BUILD b/iree/base/BUILD
index b7b42dc..39fa96f 100644
--- a/iree/base/BUILD
+++ b/iree/base/BUILD
@@ -42,6 +42,8 @@
         ":api_util",
         ":file_mapping",
         ":init",
+        ":platform_headers",
+        ":target_platform",
         ":tracing",
     ],
 )

iree/base/CMakeLists.txt

diff --git a/iree/base/CMakeLists.txt b/iree/base/CMakeLists.txt
index 8bba6da..4b41edc 100644
--- a/iree/base/CMakeLists.txt
+++ b/iree/base/CMakeLists.txt
@@ -37,6 +37,8 @@
     ::api_util
     ::file_mapping
     ::init
+    ::platform_headers
+    ::target_platform
     ::tracing
   PUBLIC
 )

iree/base/api.cc

diff --git a/iree/base/api.cc b/iree/base/api.cc
index c6e4b04..799673e 100644
--- a/iree/base/api.cc
+++ b/iree/base/api.cc
@@ -14,7 +14,6 @@
 
 #include "iree/base/api.h"
 
-#include <chrono>
 #include <cstdlib>
 #include <cstring>
 #include <string>
@@ -22,8 +21,14 @@
 #include "iree/base/api_util.h"
 #include "iree/base/file_mapping.h"
 #include "iree/base/init.h"
+#include "iree/base/platform_headers.h"
 #include "iree/base/tracing.h"
 
+#if defined(IREE_PLATFORM_ANDROID) || defined(IREE_PLATFORM_APPLE) || \
+    defined(IREE_PLATFORM_LINUX)
+#include <ctime>
+#endif
+
 namespace iree {
 
 //===----------------------------------------------------------------------===//
@@ -96,10 +101,28 @@
 //===----------------------------------------------------------------------===//
 
 IREE_API_EXPORT iree_time_t iree_time_now() {
-  auto now = std::chrono::system_clock::now();
-  auto now_nanos = std::chrono::time_point_cast<std::chrono::nanoseconds>(now);
-  auto now_nanos_since_epoch = now_nanos.time_since_epoch();
-  return now_nanos_since_epoch.count();
+#if defined(IREE_PLATFORM_WINDOWS)
+  // GetSystemTimePreciseAsFileTime requires Windows 8, add a fallback
+  // (such as using std::chrono) if older support is needed.
+  FILETIME system_time;
+  ::GetSystemTimePreciseAsFileTime(&system_time);
+
+  constexpr int64_t kUnixEpochStartTicks = 116444736000000000i64;
+  constexpr int64_t kFtToMicroSec = 10;
+  LARGE_INTEGER li;
+  li.LowPart = system_time.dwLowDateTime;
+  li.HighPart = system_time.dwHighDateTime;
+  li.QuadPart -= kUnixEpochStartTicks;
+  li.QuadPart /= kFtToMicroSec;
+  return li.QuadPart;
+#elif defined(IREE_PLATFORM_ANDROID) || defined(IREE_PLATFORM_APPLE) || \
+    defined(IREE_PLATFORM_LINUX)
+  timespec clock_time;
+  clock_gettime(CLOCK_REALTIME, &clock_time);
+  return clock_time.tv_nsec;
+#else
+#error "IREE system clock needs to be set up for your platform"
+#endif
 }
 
 IREE_API_EXPORT iree_time_t