Haiku support proposal. (#218)

* Haiku support proposal.
Basic PAL implementation.
This platform does not support TLS modes.

* MAP_NORESERVE usage

CMakeLists.txt

@@ -168,7 +168,11 @@ if(NOT DEFINED SNMALLOC_ONLY_HEADER_LIBRARY)
     set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /Zi")
     set(CMAKE_EXE_LINKER_FLAGS_RELEASE "${CMAKE_EXE_LINKER_FLAGS_RELEASE} /DEBUG")
   else()
-    add_compile_options(-fno-exceptions -fno-rtti -g -ftls-model=initial-exec -fomit-frame-pointer)
+    add_compile_options(-fno-exceptions -fno-rtti -g -fomit-frame-pointer)
+    # Static TLS model unsupported on Haiku
+    if (NOT CMAKE_SYSTEM_NAME MATCHES "Haiku")
+	    add_compile_options(-ftls-model=initial-exec)
+    endif()
     if(SNMALLOC_CI_BUILD OR (${CMAKE_BUILD_TYPE} MATCHES "Debug"))
       # Get better stack traces in CI and Debug.
       target_link_libraries(snmalloc_lib INTERFACE "-rdynamic")

src/pal/pal.h

@@ -10,6 +10,7 @@
 #  include "pal_apple.h"
 #  include "pal_freebsd.h"
 #  include "pal_freebsd_kernel.h"
+#  include "pal_haiku.h"
 #  include "pal_linux.h"
 #  include "pal_netbsd.h"
 #  include "pal_openbsd.h"
@@ -31,6 +32,8 @@ namespace snmalloc
     PALFreeBSDKernel;
 #  elif defined(__FreeBSD__)
     PALFreeBSD;
+#  elif defined(__HAIKU__)
+    PALHaiku;
 #  elif defined(__NetBSD__)
     PALNetBSD;
 #  elif defined(__OpenBSD__)

src/pal/pal_haiku.h

@@ -0,0 +1,84 @@
+#pragma once
+
+#if defined(__HAIKU__)
+#  include "pal_posix.h"
+
+#  include <sys/mman.h>
+
+namespace snmalloc
+{
+  /**
+   * Platform abstraction layer for Haiku.  This provides features for this
+   * system.
+   */
+  class PALHaiku : public PALPOSIX<PALHaiku>
+  {
+  public:
+    /**
+     * Bitmap of PalFeatures flags indicating the optional features that this
+     * PAL supports.
+     *
+     */
+    static constexpr uint64_t pal_features = PALPOSIX::pal_features;
+
+    /**
+     * Notify platform that we will not be needing these pages.
+     * Haiku does not provide madvise call per say only the posix equivalent.
+     */
+    void notify_not_using(void* p, size_t size) noexcept
+    {
+      SNMALLOC_ASSERT(is_aligned_block<page_size>(p, size));
+      posix_madvise(p, size, POSIX_MADV_DONTNEED);
+    }
+
+    /**
+     *  OS specific function for zeroing memory
+     *  using MAP_NORESERVE for explicit over commit appliance.
+     */
+    template<bool page_aligned = false>
+    void zero(void* p, size_t size)
+    {
+      if (page_aligned || is_aligned_block<page_size>(p, size))
+      {
+        SNMALLOC_ASSERT(is_aligned_block<page_size>(p, size));
+        void* r = mmap(
+          p,
+          size,
+          PROT_READ | PROT_WRITE,
+          MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED | MAP_NORESERVE,
+          -1,
+          0);
+
+        if (r != MAP_FAILED)
+          return;
+      }
+
+      bzero(p, size);
+    }
+
+    /**
+     * Reserve memory using MAP_NORESERVE for explicit
+     * over commit applicance.
+     */
+    std::pair<void*, size_t> reserve_at_least(size_t size)
+    {
+      constexpr size_t min_size =
+        bits::is64() ? bits::one_at_bit(32) : bits::one_at_bit(28);
+      auto size_request = bits::max(size, min_size);
+
+      void* p = mmap(
+        nullptr,
+        size_request,
+        PROT_READ | PROT_WRITE,
+        MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,
+        -1,
+        0);
+
+      if (p == MAP_FAILED)
+        error("Out of memory");
+
+      return {p, size_request};
+    }
+  };
+} // namespace snmalloc
+#endif