[committed] libstdc++: Remove redundant check for zero in std::__popcount

[Jonathan Wakely via Gcc-patches]

The popcount built-ins work fine for zero, so there's no need to check
for it.

libstdc++-v3/ChangeLog:

        * include/std/bit (__popcount): Remove redundant check for zero.

Tested x86_64-linux. Committed to trunk.


commit ff4bfb1553cf525d7299bbf7451ac32cfd97ae1b
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon Nov 9 14:31:13 2020

    libstdc++: Remove redundant check for zero in std::__popcount
    
    The popcount built-ins work fine for zero, so there's no need to check
    for it.
    
    libstdc++-v3/ChangeLog:
    
            * include/std/bit (__popcount): Remove redundant check for zero.

diff --git a/libstdc++-v3/include/std/bit b/libstdc++-v3/include/std/bit
index f4344820d527..16f7eba46d7b 100644
--- a/libstdc++-v3/include/std/bit
+++ b/libstdc++-v3/include/std/bit
@@ -184,9 +184,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using __gnu_cxx::__int_traits;
       constexpr auto _Nd = __int_traits<_Tp>::__digits;
 
-      if (__x == 0)
-        return 0;
-
       constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
       constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
       constexpr auto _Nd_u = __int_traits<unsigned>::__digits;