[proxy](7/n) self vendor array and algorithm headers (#722)

* [proxy](7/n) proxy array and algorithm headers

* [wip] address CRs

* undo comment

* format

* fix build

* simplify macro dispatching

src/snmalloc/backend_helpers/buddy.h

@@ -23,7 +23,7 @@ namespace snmalloc
       RBTree<Rep> tree{};
     };
 
-    std::array<Entry, MAX_SIZE_BITS - MIN_SIZE_BITS> entries{};
+    stl::Array<Entry, MAX_SIZE_BITS - MIN_SIZE_BITS> entries{};
     // All RBtrees at or above this index should be empty.
     size_t empty_at_or_above{0};
 
@@ -167,7 +167,7 @@ namespace snmalloc
       {
         if (Rep::equal(Rep::null, addr) || Rep::compare(e, addr))
         {
-          addr = std::exchange(e, addr);
+          addr = stl::exchange(e, addr);
         }
       }
 

src/snmalloc/ds_core/defines.h

@@ -130,7 +130,8 @@ namespace snmalloc
 #define TOSTRING(expr) TOSTRING2(expr)
 #define TOSTRING2(expr) #expr
 
-#ifdef __cpp_lib_source_location
+#if defined(__cpp_lib_source_location) && \
+  !defined(SNMALLOC_USE_SELF_VENDORED_STL)
 #  include <source_location>
 #  define SNMALLOC_CURRENT_LINE std::source_location::current().line()
 #  define SNMALLOC_CURRENT_FILE std::source_location::current().file_name()
@@ -203,6 +204,13 @@ namespace snmalloc
 #  define SNMALLOC_UNINITIALISED
 #endif
 
+// Check that the vendored STL is only used with GNU/Clang extensions.
+#ifdef SNMALLOC_USE_SELF_VENDORED_STL
+#  if !defined(__GNUC__) && !defined(__clang__)
+#    error "cannot use vendored STL without GNU/Clang extensions"
+#  endif
+#endif
+
 namespace snmalloc
 {
   /**

src/snmalloc/ds_core/helpers.h

@@ -2,10 +2,10 @@
 
 #include "bits.h"
 #include "snmalloc/ds_core/defines.h"
+#include "snmalloc/stl/array.h"
 #include "snmalloc/stl/type_traits.h"
 #include "snmalloc/stl/utility.h"
 
-#include <array>
 #include <stddef.h>
 
 namespace snmalloc
@@ -50,7 +50,7 @@ namespace snmalloc
     };
 
     static constexpr size_t rlength = bits::next_pow2_const(length);
-    std::array<TWrap, rlength> array;
+    stl::Array<TWrap, rlength> array;
 
   public:
     constexpr const T& operator[](const size_t i) const
@@ -65,7 +65,7 @@ namespace snmalloc
   };
 #else
   template<size_t length, typename T>
-  using ModArray = std::array<T, length>;
+  using ModArray = stl::Array<T, length>;
 #endif
 
   /**
@@ -105,7 +105,7 @@ namespace snmalloc
     template<
       typename Fn,
       typename =
-        stl::enable_if_t<!stl::is_same_v<std::decay_t<Fn>, function_ref>>>
+        stl::enable_if_t<!stl::is_same_v<stl::decay_t<Fn>, function_ref>>>
     function_ref(Fn&& fn)
     {
       data_ = static_cast<void*>(&fn);
@@ -144,7 +144,7 @@ namespace snmalloc
     /**
      * The buffer that is used to store the formatted output.
      */
-    std::array<char, BufferSize> buffer;
+    stl::Array<char, BufferSize> buffer;
 
     /**
      * Space in the buffer, excluding a trailing null terminator.
@@ -208,7 +208,7 @@ namespace snmalloc
     /**
      * Append a nullptr
      */
-    void append(std::nullptr_t)
+    void append(decltype(nullptr))
     {
       append("(nullptr)");
     }
@@ -254,7 +254,7 @@ namespace snmalloc
         append_char('-');
         s = 0 - s;
       }
-      std::array<char, 20> buf{{0}};
+      stl::Array<char, 20> buf{{0}};
       const char digits[] = "0123456789";
       for (long i = static_cast<long>(buf.size() - 1); i >= 0; i--)
       {
@@ -284,7 +284,7 @@ namespace snmalloc
     {
       append_char('0');
       append_char('x');
-      std::array<char, 16> buf{{0}};
+      stl::Array<char, 16> buf{{0}};
       const char hexdigits[] = "0123456789abcdef";
       // Length of string including null terminator
       static_assert(sizeof(hexdigits) == 0x11);

src/snmalloc/ds_core/ptrwrap.h

@@ -276,7 +276,7 @@ namespace snmalloc
     /**
      * nullptr is implicitly constructable at any bounds type
      */
-    constexpr SNMALLOC_FAST_PATH CapPtr(const std::nullptr_t n)
+    constexpr SNMALLOC_FAST_PATH CapPtr(const decltype(nullptr) n)
     : unsafe_capptr(n)
     {}
 
@@ -465,7 +465,7 @@ namespace snmalloc
     /**
      * nullptr is constructable at any bounds type
      */
-    constexpr SNMALLOC_FAST_PATH AtomicCapPtr(const std::nullptr_t n)
+    constexpr SNMALLOC_FAST_PATH AtomicCapPtr(const decltype(nullptr) n)
     : unsafe_capptr(n)
     {}
 

src/snmalloc/ds_core/redblacktree.h

@@ -1,6 +1,7 @@
 #pragma once
 
-#include <array>
+#include "snmalloc/stl/array.h"
+
 #include <stddef.h>
 #include <stdint.h>
 
@@ -259,7 +260,7 @@ namespace snmalloc
     {
       friend class RBTree;
 
-      std::array<RBStep, 128> path;
+      stl::Array<RBStep, 128> path;
       size_t length = 0;
 
       RBPath(typename Rep::Handle root)

src/snmalloc/global/memcpy.h

@@ -156,7 +156,7 @@ namespace snmalloc
      */
     SNMALLOC_UNUSED_FUNCTION
     static constexpr size_t LargestRegisterSize =
-      std::max(sizeof(uint64_t), sizeof(void*));
+      bits::max(sizeof(uint64_t), sizeof(void*));
 
     /**
      * Hook for architecture-specific optimisations.

src/snmalloc/mem/corealloc.h

@@ -222,7 +222,7 @@ namespace snmalloc
                pointer_offset(curr, rsize).template as_static<PreAllocObject>())
         {
           size_t insert_index = entropy.sample(count);
-          curr->next = std::exchange(
+          curr->next = stl::exchange(
             pointer_offset(bumpptr, insert_index * rsize)
               .template as_static<PreAllocObject>()
               ->next,

src/snmalloc/mem/freelist.h

@@ -701,11 +701,11 @@ namespace snmalloc
        */
 
       // Pointer to the first element.
-      std::array<void*, LENGTH> head{nullptr};
+      stl::Array<void*, LENGTH> head{nullptr};
       // Pointer to the reference to the last element.
       // In the empty case end[i] == &head[i]
       // This enables branch free enqueuing.
-      std::array<void**, LENGTH> end{nullptr};
+      stl::Array<void**, LENGTH> end{nullptr};
 
       [[nodiscard]] Object::BQueuePtr<BQueue>* cast_end(uint32_t ix) const
       {
@@ -724,7 +724,7 @@ namespace snmalloc
       }
 
       SNMALLOC_NO_UNIQUE_ADDRESS
-      std::array<uint16_t, RANDOM ? 2 : (TRACK_LENGTH ? 1 : 0)> length{};
+      stl::Array<uint16_t, RANDOM ? 2 : (TRACK_LENGTH ? 1 : 0)> length{};
 
     public:
       constexpr Builder() = default;

src/snmalloc/mem/remotecache.h

@@ -6,10 +6,9 @@
 #include "metadata.h"
 #include "remoteallocator.h"
 #include "sizeclasstable.h"
+#include "snmalloc/stl/array.h"
 #include "snmalloc/stl/atomic.h"
 
-#include <array>
-
 namespace snmalloc
 {
 
@@ -33,8 +32,8 @@ namespace snmalloc
   {
     static_assert(RINGS > 0);
 
-    std::array<freelist::Builder<false, true>, RINGS> open_builder;
-    std::array<address_t, RINGS> open_meta = {0};
+    stl::Array<freelist::Builder<false, true>, RINGS> open_builder;
+    stl::Array<address_t, RINGS> open_meta = {0};
 
     SNMALLOC_FAST_PATH size_t
     ring_set(typename Config::PagemapEntry::SlabMetadata* meta)
@@ -191,7 +190,7 @@ namespace snmalloc
   template<typename Config>
   struct RemoteDeallocCache
   {
-    std::array<freelist::Builder<false>, REMOTE_SLOTS> list;
+    stl::Array<freelist::Builder<false>, REMOTE_SLOTS> list;
 
     RemoteDeallocCacheBatchingImpl<Config> batching;
 

src/snmalloc/override/new.cc

@@ -16,6 +16,8 @@
 #  endif
 #endif
 
+// only define these if we are not using the vendored STL
+#ifndef SNMALLOC_USE_SELF_VENDORED_STL
 void* operator new(size_t size)
 {
   return snmalloc::libc::malloc(size);
@@ -111,3 +113,4 @@ void operator delete[](void* p, size_t size, std::align_val_t val) EXCEPTSPEC
   size = snmalloc::aligned_size(size_t(val), size);
   snmalloc::libc::free_sized(p, size);
 }
+#endif

src/snmalloc/pal/pal_concept.h

@@ -4,8 +4,6 @@
 #  include "pal_consts.h"
 #  include "pal_ds.h"
 
-#  include <utility>
-
 namespace snmalloc
 {
   /*

src/snmalloc/pal/pal_linux.h

@@ -3,6 +3,7 @@
 #if defined(__linux__)
 #  include "../ds_core/ds_core.h"
 #  include "pal_posix.h"
+#  include "snmalloc/stl/array.h"
 
 #  include <string.h>
 #  include <sys/mman.h>
@@ -183,8 +184,8 @@ namespace snmalloc
       // protected routine.
       if (false == syscall_not_working.load(stl::memory_order_relaxed))
       {
-        auto current = std::begin(buffer);
-        auto target = std::end(buffer);
+        auto current = stl::begin(buffer);
+        auto target = stl::end(buffer);
         while (auto length = target - current)
         {
           // Reading data via syscall from system entropy pool.

src/snmalloc/pal/pal_posix.h

@@ -5,6 +5,7 @@
 #if defined(SNMALLOC_BACKTRACE_HEADER)
 #  include SNMALLOC_BACKTRACE_HEADER
 #endif
+#include "snmalloc/stl/array.h"
 #include "snmalloc/stl/utility.h"
 
 #include <errno.h>
@@ -417,8 +418,8 @@ namespace snmalloc
       auto fd = open("/dev/urandom", flags, 0);
       if (fd > 0)
       {
-        auto current = std::begin(buffer);
-        auto target = std::end(buffer);
+        auto current = stl::begin(buffer);
+        auto target = stl::end(buffer);
         while (auto length = static_cast<size_t>(target - current))
         {
           ret = read(fd, current, length);

src/snmalloc/stl/array.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#ifdef SNMALLOC_USE_SELF_VENDORED_STL
+#  include "snmalloc/stl/gnu/array.h"
+#else
+#  include "snmalloc/stl/cxx/array.h"
+#endif

src/snmalloc/stl/atomic.h

@@ -1,8 +1,6 @@
 #pragma once
 
-#include "snmalloc/stl/common.h"
-
-#if SNMALLOC_USE_SELF_VENDORED_STL
+#ifdef SNMALLOC_USE_SELF_VENDORED_STL
 #  include "snmalloc/stl/gnu/atomic.h"
 #else
 #  include "snmalloc/stl/cxx/atomic.h"

src/snmalloc/stl/common.h

@@ -1,15 +0,0 @@
-#pragma once
-
-#include "snmalloc/ds_core/defines.h"
-
-// Default on using the system STL.
-#ifndef SNMALLOC_USE_SELF_VENDORED_STL
-#  define SNMALLOC_USE_SELF_VENDORED_STL 0
-#endif
-
-// Check that the vendored STL is only used with GNU/Clang extensions.
-#if SNMALLOC_USE_SELF_VENDORED_STL
-#  if !defined(__GNUC__) && !defined(__clang__)
-#    error "cannot use vendored STL without GNU/Clang extensions"
-#  endif
-#endif

src/snmalloc/stl/cxx/array.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <array>
+
+namespace snmalloc
+{
+  namespace stl
+  {
+    template<typename T, size_t N>
+    using Array = std::array<T, N>;
+
+    using std::begin;
+    using std::end;
+  } // namespace stl
+} // namespace snmalloc

src/snmalloc/stl/cxx/utility.h

@@ -5,6 +5,7 @@ namespace snmalloc
   namespace stl
   {
     using std::declval;
+    using std::exchange;
     using std::forward;
     using std::move;
     template<class T1, class T2>

src/snmalloc/stl/gnu/array.h

@@ -0,0 +1,117 @@
+#pragma once
+
+#include "snmalloc/ds_core/defines.h"
+
+#include <stddef.h>
+
+namespace snmalloc
+{
+  namespace stl
+  {
+    template<typename T, size_t N>
+    struct Array
+    {
+      // N is potentially 0, so we mark it with __extension__ attribute.
+      // Expose this to public to allow aggregate initialization
+      __extension__ T _storage[N];
+
+      [[nodiscard]] constexpr SNMALLOC_FAST_PATH size_t size() const
+      {
+        return N;
+      }
+
+      constexpr T& operator[](size_t i)
+      {
+        return _storage[i];
+      }
+
+      constexpr const T& operator[](size_t i) const
+      {
+        return _storage[i];
+      }
+
+      using value_type = T;
+      using size_type = size_t;
+      using iterator = T*;
+      using const_iterator = const T*;
+
+      [[nodiscard]] constexpr SNMALLOC_FAST_PATH iterator begin()
+      {
+        return &_storage[0];
+      }
+
+      [[nodiscard]] constexpr SNMALLOC_FAST_PATH const_iterator begin() const
+      {
+        return &_storage[0];
+      }
+
+      [[nodiscard]] constexpr SNMALLOC_FAST_PATH iterator end()
+      {
+        return &_storage[N];
+      }
+
+      [[nodiscard]] constexpr SNMALLOC_FAST_PATH const_iterator end() const
+      {
+        return &_storage[N];
+      }
+
+      [[nodiscard]] constexpr SNMALLOC_FAST_PATH T* data()
+      {
+        return &_storage[0];
+      }
+
+      [[nodiscard]] constexpr SNMALLOC_FAST_PATH const T* data() const
+      {
+        return &_storage[0];
+      }
+    };
+
+    template<typename T, size_t N>
+    constexpr T* begin(Array<T, N>& a)
+    {
+      return a.begin();
+    }
+
+    template<typename T, size_t N>
+    constexpr T* end(Array<T, N>& a)
+    {
+      return a.end();
+    }
+
+    template<typename T, size_t N>
+    constexpr const T* begin(const Array<T, N>& a)
+    {
+      return a.begin();
+    }
+
+    template<typename T, size_t N>
+    constexpr const T* end(const Array<T, N>& a)
+    {
+      return a.end();
+    }
+
+    template<typename T, size_t N>
+    constexpr T* begin(T (&a)[N])
+    {
+      return &a[0];
+    }
+
+    template<typename T, size_t N>
+    constexpr T* end(T (&a)[N])
+    {
+      return &a[N];
+    }
+
+    template<typename T, size_t N>
+    constexpr const T* begin(const T (&a)[N])
+    {
+      return &a[0];
+    }
+
+    template<typename T, size_t N>
+    constexpr const T* end(const T (&a)[N])
+    {
+      return &a[N];
+    }
+  } // namespace stl
+} // namespace snmalloc

src/snmalloc/stl/gnu/atomic.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "snmalloc/ds_core/defines.h"
 #include "snmalloc/stl/type_traits.h"
 
 #include <stddef.h>

src/snmalloc/stl/gnu/utility.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "snmalloc/ds_core/defines.h"
 #include "snmalloc/stl/type_traits.h"
 
 // This is used by clang to provide better analysis of lifetimes.
@@ -64,5 +65,13 @@ namespace snmalloc
       T1 first;
       T2 second;
     };
+
+    template<typename A, typename B = A>
+    constexpr SNMALLOC_FAST_PATH A exchange(A& obj, B&& new_value)
+    {
+      A old_value = move(obj);
+      obj = forward<B>(new_value);
+      return old_value;
+    }
   } // namespace stl
 } // namespace snmalloc

src/snmalloc/stl/type_traits.h

@@ -1,8 +1,6 @@
 #pragma once
 
-#include "snmalloc/stl/common.h"
-
-#if SNMALLOC_USE_SELF_VENDORED_STL
+#ifdef SNMALLOC_USE_SELF_VENDORED_STL
 #  include "snmalloc/stl/gnu/type_traits.h"
 #else
 #  include "snmalloc/stl/cxx/type_traits.h"

src/snmalloc/stl/utility.h

@@ -1,8 +1,6 @@
 #pragma once
 
-#include "snmalloc/stl/common.h"
-
-#if SNMALLOC_USE_SELF_VENDORED_STL
+#ifdef SNMALLOC_USE_SELF_VENDORED_STL
 #  include "snmalloc/stl/gnu/utility.h"
 #else
 #  include "snmalloc/stl/cxx/utility.h"

src/test/func/memcpy/func-memcpy.cc

@@ -30,6 +30,7 @@ int main()
 
 #  include <assert.h>
 #  include <csetjmp>
+#  include <initializer_list>
 #  include <stdio.h>
 #  include <stdlib.h>
 #  include <string.h>

src/test/func/memory/memory.cc

@@ -1,3 +1,4 @@
+#include <array>
 #include <iostream>
 #include <snmalloc/snmalloc.h>
 #include <test/opt.h>
@@ -5,6 +6,7 @@
 #include <test/xoroshiro.h>
 #include <unordered_set>
 #include <vector>
+
 #if ((defined(__linux__) && !defined(__ANDROID__)) || defined(__sun)) || \
   defined(__OpenBSD__) && !defined(SNMALLOC_QEMU_WORKAROUND)
 /*

src/test/func/thread_alloc_external/thread_alloc_external.cc

@@ -2,6 +2,7 @@
 #  undef SNMALLOC_USE_PTHREAD_DESTRUCTORS
 #endif
 
+#include <new>
 #include <snmalloc/snmalloc_core.h>
 #include <test/setup.h>