[PATCH] Add __attribute__((malloc) to allocator and remove unused code

[Jonathan Wakely]

As discussed at https://gcc.gnu.org/ml/libstdc++/2018-01/msg00073.html
we can simplify the allocator function for valarray memory. I also
noticed that the _Array(size_t) constructor is never used.

        * include/bits/valarray_array.h (__valarray_get_memory): Remove.
        (__valarray_get_storage): Call operator new directly. Remove ignored
        top-level restrict qualifier and add malloc attribute instead.
        (_Array<_Tp>::_Array(size_t)): Remove unused constructor.

Tested powerpc64le-linux, committed to trunk.



commit 71983b7d0901159af2bca65af783460721fc0a76
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon May 14 16:02:18 2018 +0100

    Add __attribute__((malloc) to allocator and remove unused code
    
            * include/bits/valarray_array.h (__valarray_get_memory): Remove.
            (__valarray_get_storage): Call operator new directly. Remove ignored
            top-level restrict qualifier and add malloc attribute instead.
            (_Array<_Tp>::_Array(size_t)): Remove unused constructor.

diff --git a/libstdc++-v3/include/bits/valarray_array.h 
b/libstdc++-v3/include/bits/valarray_array.h
index 07f38ed03ed..6759d6003e9 100644
--- a/libstdc++-v3/include/bits/valarray_array.h
+++ b/libstdc++-v3/include/bits/valarray_array.h
@@ -47,18 +47,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // Helper functions on raw pointers
   //
 
-  // We get memory by the old fashion way
-  inline void*
-  __valarray_get_memory(size_t __n)
-  { return operator new(__n); }
+  // We get memory the old fashioned way
+  template<typename _Tp>
+    _Tp*
+    __valarray_get_storage(size_t) __attribute__((__malloc__));
 
   template<typename _Tp>
-    inline _Tp*__restrict__
+    inline _Tp*
     __valarray_get_storage(size_t __n)
-    {
-      return static_cast<_Tp*__restrict__>
-       (std::__valarray_get_memory(__n * sizeof(_Tp)));
-    }
+    { return static_cast<_Tp*>(operator new(__n * sizeof(_Tp))); }
 
   // Return memory to the system
   inline void
@@ -410,7 +407,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Tp>
     struct _Array
     {
-      explicit _Array(size_t);
       explicit _Array(_Tp* const __restrict__);
       explicit _Array(const valarray<_Tp>&);
       _Array(const _Tp* __restrict__, size_t);
@@ -503,12 +499,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                    __dst._M_data, __j._M_data);
     }
 
-  template<typename _Tp>
-    inline
-    _Array<_Tp>::_Array(size_t __n)
-    : _M_data(__valarray_get_storage<_Tp>(__n))
-    { std::__valarray_default_construct(_M_data, _M_data + __n); }
-
   template<typename _Tp>
     inline
     _Array<_Tp>::_Array(_Tp* const __restrict__ __p)