[libcxx-commits] [PATCH] D93456: [libcxx] Avoid overflows in the windows __libcpp_steady_clock_now()

[Martin Storsjö via Phabricator via libcxx-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG02f1d28ed6b8: [libcxx] Avoid overflows in the windows __libcpp_steady_clock_now() (authored by mstorsjo).

Changed prior to commit:
  https://reviews.llvm.org/D93456?vs=312472&id=316232#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93456/new/

https://reviews.llvm.org/D93456

Files:
  libcxx/src/chrono.cpp
  libcxx/test/std/utilities/time/time.clock/time.clock.steady/now.pass.cpp


Index: libcxx/test/std/utilities/time/time.clock/time.clock.steady/now.pass.cpp
===================================================================
--- libcxx/test/std/utilities/time/time.clock/time.clock.steady/now.pass.cpp
+++ libcxx/test/std/utilities/time/time.clock/time.clock.steady/now.pass.cpp
@@ -25,6 +25,8 @@
     C::time_point t1 = C::now();
     C::time_point t2 = C::now();
     assert(t2 >= t1);
+    // make sure t2 didn't wrap around
+    assert(t2 > std::chrono::time_point<C>());
 
   return 0;
 }
Index: libcxx/src/chrono.cpp
===================================================================
--- libcxx/src/chrono.cpp
+++ libcxx/src/chrono.cpp
@@ -153,7 +153,10 @@
 
   LARGE_INTEGER counter;
   (void) QueryPerformanceCounter(&counter);
-  return steady_clock::time_point(steady_clock::duration(counter.QuadPart * nano::den / freq.QuadPart));
+  auto seconds = counter.QuadPart / freq.QuadPart;
+  auto fractions = counter.QuadPart % freq.QuadPart;
+  auto dur = seconds * nano::den + fractions * nano::den / freq.QuadPart;
+  return steady_clock::time_point(steady_clock::duration(dur));
 }
 
 #elif defined(CLOCK_MONOTONIC)


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