Allow memory unmapping in case of MPROTECT_VDB

Issue #271 (bdwgc).

* allchblk.c [USE_MUNMAP && MPROTECT_VDB] (GC_has_unmapped_memory):
Remove function definition.
* os_dep.c [MPROTECT_VDB && USE_MUNMAP] (GC_dirty_init): Likewise.
* doc/README.macros (USE_MUNMAP): Update the description.
* include/private/gc_priv.h [MPROTECT_VDB && USE_MUNMAP]
(GC_mprotect_dirty_init, GC_has_unmapped_memory): Remove prototype.
* include/private/gcconfig.h [USE_MUNMAP && GWW_VDB] (MPROTECT_VDB):
Do not undefine; remove TODO; remove comment.
* include/private/gcconfig.h: Remove comment that PARALLEL_MARK does
not cause undefine MPROTECT_VDB.
* os_dep.c [MPROTECT_VDB && !USE_MUNMAP] (GC_mprotect_dirty_init):
Remove macro.
* os_dep.c [MPROTECT_VDB] (GC_mprotect_dirty_init): Rename to
GC_dirty_init.
* tests/test.c [!GC_DISABLE_INCREMENTAL && (TEST_DEFAULT_VDB
|| !DEFAULT_VDB)] (main): Call GC_enable_incremental() even in case of
both MPROTECT_VDB and USE_MUNMAP are defined.

diff --git a/allchblk.c b/allchblk.c
index 030de46..e5bb6bd 100644 (file)
--- a/allchblk.c
+++ b/allchblk.c
@@ -423,24 +423,6 @@ GC_INNER void GC_unmap_old(void)
     }
 }
 
-# ifdef MPROTECT_VDB
-    GC_INNER GC_bool GC_has_unmapped_memory(void)
-    {
-      int i;
-
-      for (i = 0; i <= N_HBLK_FLS; ++i) {
-        struct hblk * h;
-        hdr * hhdr;
-
-        for (h = GC_hblkfreelist[i]; h != NULL; h = hhdr -> hb_next) {
-          hhdr = HDR(h);
-          if (!IS_MAPPED(hhdr)) return TRUE;
-        }
-      }
-      return FALSE;
-    }
-# endif /* MPROTECT_VDB */
-
 /* Merge all unmapped blocks that are adjacent to other free            */
 /* blocks.  This may involve remapping, since all blocks are either     */
 /* fully mapped or fully unmapped.                                      */

diff --git a/doc/README.macros b/doc/README.macros
index 886bb60..334560d 100644 (file)
--- a/doc/README.macros
+++ b/doc/README.macros
@@ -297,9 +297,7 @@ USE_MMAP        Use MMAP instead of sbrk to get new memory.
   Works for Linux, FreeBSD, Cygwin, Solaris and Irix.
 
 USE_MUNMAP      Causes memory to be returned to the OS under the right
-  circumstances.  This currently disables VM-based incremental collection
-  (except for Win32 with GetWriteWatch() available).
-  Works under some Unix, Linux and Windows versions.
+  circumstances.  Works under some Unix, Linux and Windows versions.
   Requires USE_MMAP except for Windows.
 
 USE_WINALLOC (Cygwin only)   Use Win32 VirtualAlloc (instead of sbrk or mmap)

diff --git a/include/private/gc_priv.h b/include/private/gc_priv.h
index 91a37a8..c084897 100644 (file)
--- a/include/private/gc_priv.h
+++ b/include/private/gc_priv.h
@@ -2386,17 +2386,11 @@ GC_EXTERN signed_word GC_bytes_found;
   GC_EXTERN ptr_t * GC_gcjobjfreelist;
 #endif
 
-#ifdef MPROTECT_VDB
-# ifdef GWW_VDB
+#if defined(MPROTECT_VDB) && defined(GWW_VDB)
     GC_INNER GC_bool GC_gww_dirty_init(void);
                         /* Returns TRUE if GetWriteWatch is available.  */
                         /* May be called repeatedly.                    */
-# endif
-# ifdef USE_MUNMAP
-    GC_INNER GC_bool GC_mprotect_dirty_init(void);
-    GC_INNER GC_bool GC_has_unmapped_memory(void);
-# endif
-#endif /* MPROTECT_VDB */
+#endif
 
 #if defined(CHECKSUMS) || defined(PROC_VDB)
   GC_INNER GC_bool GC_page_was_ever_dirty(struct hblk * h);

diff --git a/include/private/gcconfig.h b/include/private/gcconfig.h
index 5aa7980..cb54ef7 100644 (file)
--- a/include/private/gcconfig.h
+++ b/include/private/gcconfig.h
@@ -3139,15 +3139,6 @@ EXTERN_C_BEGIN
 # undef MPROTECT_VDB
 #endif
 
-#if defined(USE_MUNMAP) && defined(GWW_VDB)
-# undef MPROTECT_VDB  /* TODO: Cannot deal with address space holes. */
-  /* Else if MPROTECT_VDB is available but not GWW_VDB then decide      */
-  /* whether to disable memory unmapping or mprotect-based virtual      */
-  /* dirty bits at runtime when GC_enable_incremental is called.        */
-#endif
-
-/* PARALLEL_MARK does not cause undef MPROTECT_VDB any longer.  */
-
 #if defined(MPROTECT_VDB) && defined(GC_PREFER_MPROTECT_VDB)
   /* Choose MPROTECT_VDB manually (if multiple strategies available).   */
 # undef PCR_VDB

diff --git a/os_dep.c b/os_dep.c
index 248b23d..49f6a01 100644 (file)
--- a/os_dep.c
+++ b/os_dep.c
@@ -3278,33 +3278,8 @@ GC_API GC_push_other_roots_proc GC_CALL GC_get_push_other_roots(void)
 # endif
 #endif /* !DARWIN */
 
-#ifdef USE_MUNMAP
-  /* MPROTECT_VDB cannot deal with address space holes (for now),   */
-  /* so if the collector is configured with both MPROTECT_VDB and   */
-  /* USE_MUNMAP then, as a work around, select only one of them     */
-  /* during GC_init or GC_enable_incremental.                       */
-  GC_INNER GC_bool GC_dirty_init(void)
-  {
-    if (GC_unmap_threshold != 0) {
-      if (GETENV("GC_UNMAP_THRESHOLD") != NULL
-          || GETENV("GC_FORCE_UNMAP_ON_GCOLLECT") != NULL
-          || GC_has_unmapped_memory()) {
-        WARN("Can't maintain mprotect-based dirty bits"
-             " in case of unmapping\n", 0);
-        return FALSE;
-      }
-      GC_unmap_threshold = 0; /* in favor of incremental collection */
-      WARN("Memory unmapping is disabled as incompatible"
-           " with MPROTECT_VDB\n", 0);
-    }
-    return GC_mprotect_dirty_init();
-  }
-#else
-# define GC_mprotect_dirty_init GC_dirty_init
-#endif /* !USE_MUNMAP */
-
 #if !defined(DARWIN)
-  GC_INNER GC_bool GC_mprotect_dirty_init(void)
+  GC_INNER GC_bool GC_dirty_init(void)
   {
 #   if !defined(MSWIN32) && !defined(MSWINCE)
       struct sigaction act, oldact;
@@ -4135,7 +4110,7 @@ STATIC void *GC_mprotect_thread(void *arg)
   }
 #endif /* BROKEN_EXCEPTION_HANDLING */
 
-GC_INNER GC_bool GC_mprotect_dirty_init(void)
+GC_INNER GC_bool GC_dirty_init(void)
 {
   kern_return_t r;
   mach_port_t me;

diff --git a/tests/test.c b/tests/test.c
index 334854d..f7db849 100644 (file)
--- a/tests/test.c
+++ b/tests/test.c
@@ -1905,8 +1905,7 @@ void GC_CALLBACK warn_proc(char *msg, GC_word p)
     GC_set_warn_proc(warn_proc);
 #   if !defined(GC_DISABLE_INCREMENTAL) \
        && (defined(TEST_DEFAULT_VDB) || !defined(DEFAULT_VDB))
-#     if !defined(MAKE_BACK_GRAPH) && !defined(NO_INCREMENTAL) \
-         && !(defined(MPROTECT_VDB) && defined(USE_MUNMAP))
+#     if !defined(MAKE_BACK_GRAPH) && !defined(NO_INCREMENTAL)
         GC_enable_incremental();
 #     endif
       if (GC_is_incremental_mode()) {
@@ -2350,8 +2349,7 @@ int main(void)
 #   if !defined(GC_DISABLE_INCREMENTAL) \
        && (defined(TEST_DEFAULT_VDB) || !defined(DEFAULT_VDB))
 #     if !defined(REDIRECT_MALLOC) && !defined(MAKE_BACK_GRAPH) \
-         && !defined(USE_PROC_FOR_LIBRARIES) && !defined(NO_INCREMENTAL) \
-         && !defined(USE_MUNMAP)
+         && !defined(USE_PROC_FOR_LIBRARIES) && !defined(NO_INCREMENTAL)
         GC_enable_incremental();
 #     endif
       if (GC_is_incremental_mode()) {