libstdc++: Reduce uses of std::numeric_limits

This avoids unnecessary instantiations of std::numeric_limits or
inclusion of <limits> when a more lightweight alternative would work.
Some uses can be replaced with __gnu_cxx::__int_traits and some can just
use size_t(-1) directly where SIZE_MAX is needed.

libstdc++-v3/ChangeLog:

	* include/bits/regex.h: Use __int_traits<int> instead of
	std::numeric_limits<int>.
	* include/bits/uniform_int_dist.h: Use __int_traits<T>::__max
	instead of std::numeric_limits<T>::max().
	* include/bits/hashtable_policy.h: Use size_t(-1) instead of
	std::numeric_limits<size_t>::max().
	* include/std/regex: Include <ext/numeric_traits.h>.
	* include/std/string_view: Use typedef for __int_traits<int>.
	* src/c++11/hashtable_c++0x.cc: Use size_t(-1) instead of
	std::numeric_limits<size_t>::max().
	* testsuite/std/ranges/iota/96042.cc: Include <limits>.
	* testsuite/std/ranges/iota/difference_type.cc: Likewise.
	* testsuite/std/ranges/subrange/96042.cc: Likewise.

diff --git a/libstdc++-v3/include/bits/hashtable_policy.h b/libstdc++-v3/include/bits/hashtable_policy.h
index 0109ef86a7b524453906fd13e9eafcb17f5fe396..31ff4f16579e6ebbfd3db091b40f0d76a6d43e8c 100644 (file)
--- a/libstdc++-v3/include/bits/hashtable_policy.h
+++ b/libstdc++-v3/include/bits/hashtable_policy.h
@@ -32,8 +32,8 @@
 #define _HASHTABLE_POLICY_H 1
 
 #include <tuple>               // for std::tuple, std::forward_as_tuple
-#include <limits>              // for std::numeric_limits
 #include <bits/stl_algobase.h> // for std::min, std::is_permutation.
+#include <ext/numeric_traits.h>        // for __gnu_cxx::__int_traits
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
@@ -506,6 +506,7 @@ namespace __detail
   inline std::size_t
   __clp2(std::size_t __n) noexcept
   {
+    using __gnu_cxx::__int_traits;
     // Equivalent to return __n ? std::bit_ceil(__n) : 0;
     if (__n < 2)
       return __n;
@@ -513,7 +514,7 @@ namespace __detail
       ? __builtin_clzll(__n - 1ull)
       : __builtin_clzl(__n - 1ul);
     // Doing two shifts avoids undefined behaviour when __lz == 0.
-    return (size_t(1) << (numeric_limits<size_t>::digits - __lz - 1)) << 1;
+    return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
   }
 
   /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
@@ -556,7 +557,7 @@ namespace __detail
        // Set next resize to the max value so that we never try to rehash again
        // as we already reach the biggest possible bucket number.
        // Note that it might result in max_load_factor not being respected.
-       _M_next_resize = numeric_limits<size_t>::max();
+       _M_next_resize = size_t(-1);
       else
        _M_next_resize
          = __builtin_floorl(__res * (long double)_M_max_load_factor);

diff --git a/libstdc++-v3/include/bits/regex.h b/libstdc++-v3/include/bits/regex.h
index 31ebcc1eb861511634328e93b7fe218d39adc94d..15e4289bf95e36fc190ae64c7c81171d88a4b0ca 100644 (file)
--- a/libstdc++-v3/include/bits/regex.h
+++ b/libstdc++-v3/include/bits/regex.h
@@ -973,11 +973,12 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
          if (const size_t __n = std::min(_M_len, __s._M_len))
            if (int __ret = traits_type::compare(_M_data, __s._M_data, __n))
              return __ret;
+         using __limits = __gnu_cxx::__int_traits<int>;
          const difference_type __diff = _M_len - __s._M_len;
-         if (__diff > std::numeric_limits<int>::max())
-           return std::numeric_limits<int>::max();
-         if (__diff < std::numeric_limits<int>::min())
-           return std::numeric_limits<int>::min();
+         if (__diff > __limits::__max)
+           return __limits::__max;
+         if (__diff < __limits::__min)
+           return __limits::__min;
          return static_cast<int>(__diff);
        }
 

diff --git a/libstdc++-v3/include/bits/uniform_int_dist.h b/libstdc++-v3/include/bits/uniform_int_dist.h
index e3d7934e9977c632de63bd9821f0bda921c2cd8c..6e1e3d5fc5fe8f7f22e62a85b35dc8bfa4743372 100644 (file)
--- a/libstdc++-v3/include/bits/uniform_int_dist.h
+++ b/libstdc++-v3/include/bits/uniform_int_dist.h
@@ -32,7 +32,7 @@
 #define _GLIBCXX_BITS_UNIFORM_INT_DIST_H
 
 #include <type_traits>
-#include <limits>
+#include <ext/numeric_traits.h>
 #if __cplusplus > 201703L
 # include <concepts>
 #endif
@@ -88,7 +88,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
        explicit
        param_type(_IntType __a,
-                  _IntType __b = numeric_limits<_IntType>::max())
+                  _IntType __b = __gnu_cxx::__int_traits<_IntType>::__max)
        : _M_a(__a), _M_b(__b)
        {
          __glibcxx_assert(_M_a <= _M_b);
@@ -126,7 +126,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        */
       explicit
       uniform_int_distribution(_IntType __a,
-                              _IntType __b = numeric_limits<_IntType>::max())
+                              _IntType __b
+                                = __gnu_cxx::__int_traits<_IntType>::__max)
       : _M_param(__a, __b)
       { }
 

diff --git a/libstdc++-v3/include/std/regex b/libstdc++-v3/include/std/regex
index b4b8ea7daca90e7ce7ddefa7c3f1befe47c17446..43ee1aee616284e72ebc744a14d2c86d66881d55 100644 (file)
--- a/libstdc++-v3/include/std/regex
+++ b/libstdc++-v3/include/std/regex
@@ -53,6 +53,7 @@
 #include <cstring>
 
 #include <ext/aligned_buffer.h>
+#include <ext/numeric_traits.h>
 #include <bits/std_function.h>
 #include <bits/regex_constants.h>
 #include <bits/regex_error.h>

diff --git a/libstdc++-v3/include/std/string_view b/libstdc++-v3/include/std/string_view
index 32c51b2bbd4c4438d0f10fa21ac1af732815364e..656d06bf90e9addb2ea127962dba5dc961a37f9c 100644 (file)
--- a/libstdc++-v3/include/std/string_view
+++ b/libstdc++-v3/include/std/string_view
@@ -459,11 +459,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       static constexpr int
       _S_compare(size_type __n1, size_type __n2) noexcept
       {
+       using __limits = __gnu_cxx::__int_traits<int>;
        const difference_type __diff = __n1 - __n2;
-       if (__diff > __gnu_cxx::__int_traits<int>::__max)
-         return __gnu_cxx::__int_traits<int>::__max;
-       if (__diff < __gnu_cxx::__int_traits<int>::__min)
-         return __gnu_cxx::__int_traits<int>::__min;
+       if (__diff > __limits::__max)
+         return __limits::__max;
+       if (__diff < __limits::__min)
+         return __limits::__min;
        return static_cast<int>(__diff);
       }
 

diff --git a/libstdc++-v3/src/c++11/hashtable_c++0x.cc b/libstdc++-v3/src/c++11/hashtable_c++0x.cc
index de8e2c7cb915bec8f9066bb00cfb60db49e3adca..62762f34cafc0a65b57e0a0dd22d2a0e471e6dd9 100644 (file)
--- a/libstdc++-v3/src/c++11/hashtable_c++0x.cc
+++ b/libstdc++-v3/src/c++11/hashtable_c++0x.cc
@@ -78,7 +78,7 @@ namespace __detail
       // Set next resize to the max value so that we never try to rehash again
       // as we already reach the biggest possible bucket number.
       // Note that it might result in max_load_factor not being respected.
-      _M_next_resize = numeric_limits<size_t>::max();
+      _M_next_resize = size_t(-1);
     else
       _M_next_resize =
        __builtin_floorl(*__next_bkt * (long double)_M_max_load_factor);

diff --git a/libstdc++-v3/testsuite/std/ranges/iota/96042.cc b/libstdc++-v3/testsuite/std/ranges/iota/96042.cc
index 911663bc41396d1c42b3cf4f29176ccdff3c3bb0..b2374ff9397a1b1d8e3d462154e4cdfcfb4d51e5 100644 (file)
--- a/libstdc++-v3/testsuite/std/ranges/iota/96042.cc
+++ b/libstdc++-v3/testsuite/std/ranges/iota/96042.cc
@@ -19,6 +19,7 @@
 // { dg-do compile { target c++2a } }
 
 #include <ranges>
+#include <limits>
 
 void
 test01()

diff --git a/libstdc++-v3/testsuite/std/ranges/iota/difference_type.cc b/libstdc++-v3/testsuite/std/ranges/iota/difference_type.cc
index 6eb1a1676f7da885c6f5738195fab413a4d8e66c..c6a06a27d66902e4dc958fd6906d87829c0fbd9d 100644 (file)
--- a/libstdc++-v3/testsuite/std/ranges/iota/difference_type.cc
+++ b/libstdc++-v3/testsuite/std/ranges/iota/difference_type.cc
@@ -19,6 +19,7 @@
 // { dg-do run { target c++2a } }
 
 #include <ranges>
+#include <limits>
 #include <testsuite_hooks.h>
 
 void

diff --git a/libstdc++-v3/testsuite/std/ranges/subrange/96042.cc b/libstdc++-v3/testsuite/std/ranges/subrange/96042.cc
index 5826203f03c781c887d1cf1d02c2167f2e1b1d63..8cf9ba8ad760d1aea0cf36d9cb157cd9f638cee5 100644 (file)
--- a/libstdc++-v3/testsuite/std/ranges/subrange/96042.cc
+++ b/libstdc++-v3/testsuite/std/ranges/subrange/96042.cc
@@ -19,6 +19,7 @@
 // { dg-do compile { target c++2a } }
 
 #include <ranges>
+#include <limits>
 
 constexpr bool
 test01()