Remove compaction support detection using sysconf

Except on Windows and MinGW, we can only use compaction on systems that
use mmap (only systems that use mmap can use the read barrier that
compaction requires). We don't need to separately detect whether we can
support compaction or not.

1 files changed, 3 insertions, 35 deletions

diff --git a/gc.c b/gc.c
index c3ecb385dd..936874daba 100644
--- a/gc.c
+++ b/gc.c
@@ -3417,17 +3417,6 @@ Init_heap(void)
 {
     rb_objspace_t *objspace = &rb_objspace;
 
-#if defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)
-    /* If Ruby's heap pages are not a multiple of the system page size, we
-     * cannot use mprotect for the read barrier, so we must disable automatic
-     * compaction. */
-    int pagesize;
-    pagesize = (int)sysconf(_SC_PAGE_SIZE);
-    if ((HEAP_PAGE_SIZE % pagesize) != 0) {
-        ruby_enable_autocompact = 0;
-    }
-#endif
-
 #if defined(HAVE_MMAP) && !HAVE_CONST_PAGE_SIZE && !defined(PAGE_MAX_SIZE)
     /* Need to determine if we can use mmap at runtime. */
 # ifdef PAGE_SIZE
@@ -3435,7 +3424,7 @@ Init_heap(void)
     use_mmap_aligned_alloc = PAGE_SIZE <= HEAP_PAGE_SIZE;
 # elif defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)
     /* If we can use sysconf to determine the page size. */
-    use_mmap_aligned_alloc = pagesize <= HEAP_PAGE_SIZE;
+    use_mmap_aligned_alloc = sysconf(_SC_PAGE_SIZE) <= HEAP_PAGE_SIZE;
 # else
     /* Otherwise we can't determine the system page size, so don't use mmap. */
     use_mmap_aligned_alloc = FALSE;
@@ -9256,18 +9245,8 @@ gc_start_internal(rb_execution_context_t *ec, VALUE self, VALUE full_mark, VALUE
 
     /* For now, compact implies full mark / sweep, so ignore other flags */
     if (RTEST(compact)) {
-#if defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)
-        /* If Ruby's heap pages are not a multiple of the system page size, we
-         * cannot use mprotect for the read barrier, so we must disable compaction. */
-        int pagesize;
-        pagesize = (int)sysconf(_SC_PAGE_SIZE);
-        if ((HEAP_PAGE_SIZE % pagesize) != 0) {
-            rb_raise(rb_eNotImpError, "Compaction isn't available on this platform");
-        }
-#endif
-
-    /* If not MinGW, Windows, or does not have mmap, we cannot use mprotect for
-     * the read barrier, so we must disable compaction. */
+        /* If not MinGW, Windows, or does not have mmap, we cannot use mprotect for
+         * the read barrier, so we must disable compaction. */
 #if !defined(__MINGW32__) && !defined(_WIN32)
         if (!USE_MMAP_ALIGNED_ALLOC) {
             rb_raise(rb_eNotImpError, "Compaction isn't available on this platform");
@@ -10744,17 +10723,6 @@ gc_disable(rb_execution_context_t *ec, VALUE _)
 static VALUE
 gc_set_auto_compact(rb_execution_context_t *ec, VALUE _, VALUE v)
 {
-#if defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)
-    /* If Ruby's heap pages are not a multiple of the system page size, we
-     * cannot use mprotect for the read barrier, so we must disable automatic
-     * compaction. */
-    int pagesize;
-    pagesize = (int)sysconf(_SC_PAGE_SIZE);
-    if ((HEAP_PAGE_SIZE % pagesize) != 0) {
-        rb_raise(rb_eNotImpError, "Automatic compaction isn't available on this platform");
-    }
-#endif
-
     /* If not MinGW, Windows, or does not have mmap, we cannot use mprotect for
      * the read barrier, so we must disable automatic compaction. */
 #if !defined(__MINGW32__) && !defined(_WIN32)