commit f32274891bc1b8142fc6ee6de9152c3548784629
author Joerg Sonnenberger <joerg@bec.de> Thu Feb 18 15:15:53 2021 +0100
committer Copybara-Service <copybara-worker@google.com> Mon Apr 12 11:27:20 2021 -0700
tree 5e6f26812fba0c47a11f1d8a24d807c5b84e4afb
parent 4b2a43116754ae16c6e03235cbbc1506d5beb596

[libc++] Avoid <climits> dependency in <thread>

The standard guarantees sleep durations of 2^63-1 nanoseconds to work.
Instead of depending on INT64_MAX or ULONGLONG_MAX to exist via the
header pollution, fold the constant directly. That has the additional
positive side effect that it avoids long double arithmetic bugs in GCC.

Differential Revision: https://reviews.llvm.org/D99516

GitOrigin-RevId: 9f4022ffeb20eff91c7461828592dc812ee5a28e

include/thread

diff --git a/include/thread b/include/thread
index 34e0c2a..ff3c746 100644
--- a/include/thread
+++ b/include/thread
@@ -362,12 +362,11 @@
 {
     if (__d > chrono::duration<_Rep, _Period>::zero())
     {
-#if defined(_LIBCPP_COMPILER_GCC) && (__powerpc__ || __POWERPC__)
-    //  GCC's long double const folding is incomplete for IBM128 long doubles.
-        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max = chrono::duration<long double>(ULLONG_MAX/1000000000ULL) ;
-#else
-        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max = chrono::nanoseconds::max();
-#endif
+        // The standard guarantees a 64bit signed integer resolution for nanoseconds,
+        // so use INT64_MAX / 1e9 as cut-off point. Use a constant to avoid <climits>
+        // and issues with long double folding on PowerPC with GCC.
+        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max =
+            chrono::duration<long double>(9223372036.0L);
         chrono::nanoseconds __ns;
         if (__d < _Max)
         {