libstdc++: Remove redundant overflow check for futex timeout [PR 93456]

The relative_timespec function already checks for the case where the
specified timeout is in the past, so the difference can never be
negative. That means we dn't need to check if it's more negative than
the minimum time_t value.

libstdc++-v3/ChangeLog:

	PR libstdc++/93456
	* src/c++11/futex.cc (relative_timespec): Remove redundant check
	negative values.
	* testsuite/30_threads/future/members/wait_until_overflow.cc: Moved to...
	* testsuite/30_threads/future/members/93456.cc: ...here.

diff --git a/libstdc++-v3/src/c++11/futex.cc b/libstdc++-v3/src/c++11/futex.cc
index 15959cebee57c6c785437ac27525cdf7d84a3a8f..c008798318c93670deaf7acd733312f74b04a5b2 100644 (file)
--- a/libstdc++-v3/src/c++11/futex.cc
+++ b/libstdc++-v3/src/c++11/futex.cc
@@ -73,21 +73,23 @@ namespace
        return rt;
       }
 
-    auto rel_s = abs_s.count() - now_s;
+    const auto rel_s = abs_s.count() - now_s;
 
-    // Avoid overflows
+    // Convert the absolute timeout to a relative timeout, without overflow.
     if (rel_s > __int_traits<time_t>::__max) [[unlikely]]
-      rel_s = __int_traits<time_t>::__max;
-    else if (rel_s < __int_traits<time_t>::__min) [[unlikely]]
-      rel_s = __int_traits<time_t>::__min;
-
-    // Convert the absolute timeout value to a relative timeout
-    rt.tv_sec = rel_s;
-    rt.tv_nsec = abs_ns.count() - now_ns;
-    if (rt.tv_nsec < 0)
       {
-       rt.tv_nsec += 1000000000;
-       --rt.tv_sec;
+       rt.tv_sec = __int_traits<time_t>::__max;
+       rt.tv_nsec = 999999999;
+      }
+    else
+      {
+       rt.tv_sec = rel_s;
+       rt.tv_nsec = abs_ns.count() - now_ns;
+       if (rt.tv_nsec < 0)
+         {
+           rt.tv_nsec += 1000000000;
+           --rt.tv_sec;
+         }
       }
 
     return rt;

diff --git a/libstdc++-v3/testsuite/30_threads/future/members/wait_until_overflow.cc b/libstdc++-v3/testsuite/30_threads/future/members/93456.cc
similarity index 100%
rename from libstdc++-v3/testsuite/30_threads/future/members/wait_until_overflow.cc
rename to libstdc++-v3/testsuite/30_threads/future/members/93456.cc