libstdc++: Test that integral simd reductions are precise

Signed-off-by: Matthias Kretz <m.kretz@gsi.de>

libstdc++-v3/ChangeLog:

	* testsuite/experimental/simd/tests/reductions.cc: Introduce
	max_distance as the type-dependent max error.

(cherry picked from commit 8fda668e0919af9ceda9435f02a1708b375b2913)

1 files changed, 2 insertions, 1 deletions

diff --git a/libstdc++-v3/testsuite/experimental/simd/tests/reductions.cc b/libstdc++-v3/testsuite/experimental/simd/tests/reductions.cc
index 1f20961825b..07ab50a2312 100644
--- a/libstdc++-v3/testsuite/experimental/simd/tests/reductions.cc
+++ b/libstdc++-v3/testsuite/experimental/simd/tests/reductions.cc
@@ -114,6 +114,7 @@ template <typename V>
       T acc = x[0];
       for (size_t i = 1; i < V::size(); ++i)
 	acc += x[i];
-      ULP_COMPARE(reduce(x), acc, V::size() / 2).on_failure("x = ", x);
+      const T max_distance = std::is_integral_v<T> ? 0 : V::size() / 2;
+      ULP_COMPARE(reduce(x), acc, max_distance).on_failure("x = ", x);
     });
   }