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

src/snmalloc/backend_helpers/buddy.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "../ds/ds.h"
+#include "snmalloc/proxy/algorithm.h"
 
 namespace snmalloc
 {
@@ -23,7 +24,7 @@ namespace snmalloc
       RBTree<Rep> tree{};
     };
 
-    std::array<Entry, MAX_SIZE_BITS - MIN_SIZE_BITS> entries{};
+    proxy::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 +168,7 @@ namespace snmalloc
       {
         if (Rep::equal(Rep::null, addr) || Rep::compare(e, addr))
         {
-          addr = std::exchange(e, addr);
+          addr = proxy::exchange(e, addr);
         }
       }
 

src/snmalloc/ds_core/bits.h

@@ -371,9 +371,9 @@ namespace snmalloc
     }
 
     /**
-     * Implementation of `std::min`
+     * Implementation of `proxy::min`
      *
-     * `std::min` is in `<algorithm>`, so pulls in a lot of unneccessary code
+     * `proxy::min` is in `<algorithm>`, so pulls in a lot of unneccessary code
      * We write our own to reduce the code that potentially needs reviewing.
      */
     template<typename T>
@@ -383,9 +383,9 @@ namespace snmalloc
     }
 
     /**
-     * Implementation of `std::max`
+     * Implementation of `proxy::max`
      *
-     * `std::max` is in `<algorithm>`, so pulls in a lot of unneccessary code
+     * `proxy::max` is in `<algorithm>`, so pulls in a lot of unneccessary code
      * We write our own to reduce the code that potentially needs reviewing.
      */
     template<typename T>

src/snmalloc/ds_core/defines.h

@@ -130,7 +130,11 @@ namespace snmalloc
 #define TOSTRING(expr) TOSTRING2(expr)
 #define TOSTRING2(expr) #expr
 
-#ifdef __cpp_lib_source_location
+#ifndef SNMALLOC_USE_SELF_VENDORED_STL
+#  define SNMALLOC_USE_SELF_VENDORED_STL 0
+#endif
+
+#if defined(__cpp_lib_source_location) && !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()

src/snmalloc/ds_core/helpers.h

@@ -2,10 +2,10 @@
 
 #include "bits.h"
 #include "snmalloc/ds_core/defines.h"
+#include "snmalloc/proxy/array.h"
 #include "snmalloc/proxy/type_traits.h"
 #include "snmalloc/proxy/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;
+    proxy::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 = proxy::Array<T, length>;
 #endif
 
   /**
@@ -105,7 +105,7 @@ namespace snmalloc
     template<
       typename Fn,
       typename =
-        proxy::enable_if_t<!proxy::is_same_v<std::decay_t<Fn>, function_ref>>>
+        proxy::enable_if_t<!proxy::is_same_v<proxy::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;
+    proxy::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}};
+      proxy::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}};
+      proxy::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/proxy/array.h"
+
 #include <stddef.h>
 #include <stdint.h>
 
@@ -260,7 +261,7 @@ namespace snmalloc
     {
       friend class RBTree;
 
-      std::array<RBStep, 128> path;
+      proxy::Array<RBStep, 128> path;
       size_t length = 0;
 
       RBPath(typename Rep::Handle root)

src/snmalloc/global/memcpy.h

@@ -1,5 +1,6 @@
 #pragma once
 #include "bounds_checks.h"
+#include "snmalloc/proxy/algorithm.h"
 
 namespace snmalloc
 {
@@ -156,7 +157,7 @@ namespace snmalloc
      */
     SNMALLOC_UNUSED_FUNCTION
     static constexpr size_t LargestRegisterSize =
-      std::max(sizeof(uint64_t), sizeof(void*));
+      proxy::max(sizeof(uint64_t), sizeof(void*));
 
     /**
      * Hook for architecture-specific optimisations.

src/snmalloc/mem/corealloc.h

@@ -6,6 +6,7 @@
 #include "pool.h"
 #include "remotecache.h"
 #include "sizeclasstable.h"
+#include "snmalloc/proxy/algorithm.h"
 #include "snmalloc/proxy/new.h"
 #include "ticker.h"
 
@@ -222,7 +223,7 @@ namespace snmalloc
                pointer_offset(curr, rsize).template as_static<PreAllocObject>())
         {
           size_t insert_index = entropy.sample(count);
-          curr->next = std::exchange(
+          curr->next = proxy::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};
+      proxy::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};
+      proxy::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{};
+      proxy::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/proxy/array.h"
 #include "snmalloc/proxy/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};
+    proxy::Array<freelist::Builder<false, true>, RINGS> open_builder;
+    proxy::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;
+    proxy::Array<freelist::Builder<false>, REMOTE_SLOTS> list;
 
     RemoteDeallocCacheBatchingImpl<Config> batching;
 

src/snmalloc/override/new.cc

@@ -16,6 +16,12 @@
 #  endif
 #endif
 
+#ifndef SNMALLOC_USE_SELF_VENDORED_STL
+#  define SNMALLOC_USE_SELF_VENDORED_STL 0
+#endif
+
+// only define these if we are not using the vendored STL
+#if !SNMALLOC_USE_SELF_VENDORED_STL
 void* operator new(size_t size)
 {
   return snmalloc::libc::malloc(size);
@@ -111,3 +117,4 @@ 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_linux.h

@@ -183,8 +183,8 @@ namespace snmalloc
       // protected routine.
       if (false == syscall_not_working.load(proxy::memory_order_relaxed))
       {
-        auto current = std::begin(buffer);
-        auto target = std::end(buffer);
+        auto current = proxy::begin(buffer);
+        auto target = proxy::end(buffer);
         while (auto length = target - current)
         {
           // Reading data via syscall from system entropy pool.

src/snmalloc/pal/pal_posix.h

@@ -419,8 +419,8 @@ namespace snmalloc
       auto fd = open("/dev/urandom", flags, 0);
       if (fd > 0)
       {
-        auto current = std::begin(buffer);
-        auto target = std::end(buffer);
+        auto current = proxy::begin(buffer);
+        auto target = proxy::end(buffer);
         while (auto length = static_cast<size_t>(target - current))
         {
           ret = read(fd, current, length);

src/snmalloc/proxy/algorithm.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include "snmalloc/ds_core/defines.h"
+
+#ifndef SNMALLOC_USE_SELF_VENDORED_STL
+#  define SNMALLOC_USE_SELF_VENDORED_STL 0
+#endif
+
+#if SNMALLOC_USE_SELF_VENDORED_STL
+#  include "snmalloc/proxy/utility.h"
+#  if !defined(__GNUC__) && !defined(__clang__)
+#    error "cannot use vendored STL without GNU/Clang extensions"
+#  endif
+
+namespace snmalloc
+{
+  namespace proxy
+  {
+    template<typename T>
+    constexpr SNMALLOC_FAST_PATH const T& max(const T& a, const T& b)
+    {
+      return a < b ? b : a;
+    }
+
+    template<typename T>
+    constexpr SNMALLOC_FAST_PATH const T& min(const T& a, const T& b)
+    {
+      return a < b ? a : b;
+    }
+
+    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 proxy
+} // namespace snmalloc
+#else
+#  include <algorithm>
+
+namespace snmalloc
+{
+  namespace proxy
+  {
+    using std::exchange;
+    using std::max;
+    using std::min;
+  } // namespace proxy
+} // namespace snmalloc
+#endif