Revert "Disable auto compaction on platforms that can't support it"

This reverts commit 63ad55cd88.

Revert "Disable read barrier on explicit compaction request"

This reverts commit 490b57783d.

gc.c

@@ -682,7 +682,7 @@ typedef struct rb_objspace {
 	unsigned int dont_gc : 1;
 	unsigned int dont_incremental : 1;
 	unsigned int during_gc : 1;
-        unsigned int during_compacting : 2;
+        unsigned int during_compacting : 1;
 	unsigned int gc_stressful: 1;
 	unsigned int has_hook: 1;
 	unsigned int during_minor_gc : 1;
@@ -3090,17 +3090,6 @@ 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
-
     objspace->next_object_id = INT2FIX(OBJ_ID_INITIAL);
     objspace->id_to_obj_tbl = st_init_table(&object_id_hash_type);
     objspace->obj_to_id_tbl = st_init_numtable();
@@ -4400,11 +4389,6 @@ static VALUE gc_move(rb_objspace_t *objspace, VALUE scan, VALUE free);
 static void
 lock_page_body(rb_objspace_t *objspace, struct heap_page_body *body)
 {
-    /* If this is an explicit compaction (GC.compact), we don't need a read
-     * barrier, so just return early. */
-    if (objspace->flags.during_compacting >> 1) {
-        return;
-    }
 #if defined(_WIN32)
     DWORD old_protect;
 
@@ -4421,11 +4405,6 @@ lock_page_body(rb_objspace_t *objspace, struct heap_page_body *body)
 static void
 unlock_page_body(rb_objspace_t *objspace, struct heap_page_body *body)
 {
-    /* If this is an explicit compaction (GC.compact), we don't need a read
-     * barrier, so just return early. */
-    if (objspace->flags.during_compacting >> 1) {
-        return;
-    }
 #if defined(_WIN32)
     DWORD old_protect;
 
@@ -7051,7 +7030,7 @@ gc_marks_start(rb_objspace_t *objspace, int full_mark)
 #endif
 	objspace->flags.during_minor_gc = FALSE;
         if (ruby_enable_autocompact) {
-            objspace->flags.during_compacting |= TRUE;
+            objspace->flags.during_compacting = TRUE;
         }
 	objspace->profile.major_gc_count++;
 	objspace->rgengc.uncollectible_wb_unprotected_objects = 0;
@@ -8078,9 +8057,7 @@ gc_start(rb_objspace_t *objspace, int reason)
 
     /* reason may be clobbered, later, so keep set immediate_sweep here */
     objspace->flags.immediate_sweep = !!((unsigned)reason & GPR_FLAG_IMMEDIATE_SWEEP);
-
-    /* Explicitly enable compaction (GC.compact) */
-    objspace->flags.during_compacting = (!!((unsigned)reason & GPR_FLAG_COMPACT) << 1);
+    objspace->flags.during_compacting = !!((unsigned)reason & GPR_FLAG_COMPACT);
 
     if (!heap_allocated_pages) return FALSE; /* heap is not ready */
     if (!(reason & GPR_FLAG_METHOD) && !ready_to_gc(objspace)) return TRUE; /* GC is not allowed */
@@ -9270,19 +9247,6 @@ heap_check_moved_i(void *vstart, void *vend, size_t stride, void *data)
     return 0;
 }
 
-static VALUE
-gc_compact(rb_execution_context_t *ec, VALUE self)
-{
-    /* Clear the heap. */
-    gc_start_internal(ec, self, Qtrue, Qtrue, Qtrue, Qfalse);
-
-    /* At this point, all references are live and the mutator is not allowed
-     * to run, so we don't need a read barrier. */
-    gc_start_internal(ec, self, Qtrue, Qtrue, Qtrue, Qtrue);
-
-    return gc_compact_stats(ec, self);
-}
-
 static VALUE
 gc_verify_compaction_references(rb_execution_context_t *ec, VALUE self, VALUE double_heap, VALUE toward_empty)
 {
@@ -9901,16 +9865,6 @@ 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
     ruby_enable_autocompact = RTEST(v);
     return v;
 }

gc.rb

@@ -199,7 +199,8 @@ module GC
   end
 
   def self.compact
-    Primitive.gc_compact
+    Primitive.gc_start_internal true, true, true, true
+    Primitive.gc_compact_stats
   end
 
   # call-seq:

test/ruby/test_gc_compact.rb

@@ -1,15 +1,8 @@
 # frozen_string_literal: true
 require 'test/unit'
 require 'fiddle'
-require 'etc'
 
 class TestGCCompact < Test::Unit::TestCase
-  class AutoCompact < Test::Unit::TestCase
-    def setup
-      skip "autocompact not supported on this platform" unless supports_auto_compact?
-      super
-    end
-
   def test_enable_autocompact
     before = GC.auto_compact
     GC.auto_compact = true
@@ -60,25 +53,6 @@ class TestGCCompact < Test::Unit::TestCase
     GC.auto_compact = before
   end
 
-    private
-
-    def supports_auto_compact?
-      return true unless defined?(Etc::SC_PAGE_SIZE)
-
-      begin
-        return GC::INTERNAL_CONSTANTS[:HEAP_PAGE_SIZE] % Etc.sysconf(Etc::SC_PAGE_SIZE) == 0
-      rescue NotImplementedError
-      rescue ArgumentError
-      end
-
-      true
-    end
-  end
-
-  def os_page_size
-    return true unless defined?(Etc::SC_PAGE_SIZE)
-  end
-
   def test_gc_compact_stats
     list = []