[commit: ghc] master: Revert "rts: Enable two-step allocator on FreeBSD" (6715373)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/671537364ae09dc65d4bb1c646aa80e9c8f808df/ghc

>---------------------------------------------------------------

commit 671537364ae09dc65d4bb1c646aa80e9c8f808df
Author: Ben Gamari <ben at smart-cactus.org>
Date:   Fri Jul 6 14:12:03 2018 -0400

    Revert "rts: Enable two-step allocator on FreeBSD"
    
    This reverts commit 8736715857d08cc1f88d766c257b39c05df20639.
    
    I hadn't intended on merging this.


>---------------------------------------------------------------

671537364ae09dc65d4bb1c646aa80e9c8f808df
 configure.ac      | 17 ++++++++---------
 rts/posix/OSMem.c | 11 +++--------
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/configure.ac b/configure.ac
index 1976530..ac464b6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1182,23 +1182,22 @@ if test "$ac_cv_sizeof_void_p" -eq 8 ; then
     if test "x$EnableLargeAddressSpace" = "xyes" ; then
         if test "$ghc_host_os" = "darwin" ; then
             use_large_address_space=yes
-        elif test "$ghc_host_os" = "openbsd" ; then
-            # as of OpenBSD 5.8 (2015), OpenBSD does not support mmap with MAP_NORESERVE.
-            # The flag MAP_NORESERVE is supported for source compatibility reasons,
-            # but is completely ignored by OS mmap
+	elif test "$ghc_host_os" = "openbsd" ; then
+	    # as of OpenBSD 5.8 (2015), OpenBSD does not support mmap with MAP_NORESERVE.
+	    # The flag MAP_NORESERVE is supported for source compatibility reasons,
+	    # but is completely ignored by OS mmap
             use_large_address_space=no
         else
-            AC_CHECK_DECLS([MAP_NORESERVE, MAP_GUARD, MADV_FREE, MADV_DONTNEED],[],[],
+            AC_CHECK_DECLS([MAP_NORESERVE, MADV_FREE, MADV_DONTNEED],[],[],
                 [
                 #include <unistd.h>
                 #include <sys/types.h>
                 #include <sys/mman.h>
                 #include <fcntl.h>
             ])
-            if ( test "$ac_cv_have_decl_MAP_NORESERVE" = "yes" ||
-                 test "$ac_cv_have_decl_MAP_GUARD" = "yes" ) &&
-                ( test "$ac_cv_have_decl_MADV_FREE" = "yes" ||
-                test "$ac_cv_have_decl_MADV_DONTNEED" = "yes" ) ; then
+            if test "$ac_cv_have_decl_MAP_NORESERVE" = "yes" &&
+                test "$ac_cv_have_decl_MADV_FREE" = "yes" ||
+                test "$ac_cv_have_decl_MADV_DONTNEED" = "yes" ; then
                     use_large_address_space=yes
             fi
         fi
diff --git a/rts/posix/OSMem.c b/rts/posix/OSMem.c
index 08f9635..e63e798 100644
--- a/rts/posix/OSMem.c
+++ b/rts/posix/OSMem.c
@@ -102,10 +102,8 @@ void osMemInit(void)
  The naming is chosen from the Win32 API (VirtualAlloc) which does the
  same thing and has done so forever, while support for this in Unix systems
  has only been added recently and is hidden in the posix portability mess.
- The Linux manpage suggests that mmap must be passed MAP_NORESERVE in order
- to get reservation-only behavior. It is confusing because to get the reserve
- behavior we need MAP_NORESERVE (which tells the kernel not to allocate backing
- space), but heh...
+ It is confusing because to get the reserve behavior we need MAP_NORESERVE
+ (which tells the kernel not to allocate backing space), but heh...
 */
 enum
 {
@@ -163,10 +161,7 @@ my_mmap (void *addr, W_ size, int operation)
     else
         prot = PROT_NONE;
     if (operation == MEM_RESERVE)
-# if defined(MAP_GUARD)
-        // Provided by FreeBSD
-        flags = MAP_GUARD;
-# elif defined(MAP_NORESERVE)
+# if defined(MAP_NORESERVE)
         flags = MAP_NORESERVE;
 # else
 #  if defined(USE_LARGE_ADDRESS_SPACE)