Include runtime checks for compaction support

Commit 0c36ba53192c5a0d245c9b626e4346a32d7d144e changed GC compaction
methods to not be implemented when not supported. However, that commit
only does compile time checks (which currently only checks for WASM),
but there are additional compaction support checks during run time.

This commit changes it so that GC compaction methods aren't defined
during run time if the platform does not support GC compaction.

[Bug #18829]

1 files changed, 26 insertions, 48 deletions

diff --git a/gc.c b/gc.c
index 0f1c801613..4aa7d18401 100644
--- a/gc.c
+++ b/gc.c
@@ -5192,6 +5192,14 @@ static void invalidate_moved_page(rb_objspace_t *objspace, struct heap_page *pag
 #endif
 #endif
 
+#if defined(__MINGW32__) || defined(_WIN32)
+# define GC_COMPACTION_SUPPORTED 1
+#else
+/* If not MinGW, Windows, or does not have mmap, we cannot use mprotect for
+ * the read barrier, so we must disable compaction. */
+# define GC_COMPACTION_SUPPORTED (GC_CAN_COMPILE_COMPACTION && HEAP_PAGE_ALLOC_USE_MMAP)
+#endif
+
 #if GC_CAN_COMPILE_COMPACTION
 static void
 read_barrier_handler(uintptr_t address)
@@ -9567,17 +9575,7 @@ 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 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 (!HEAP_PAGE_ALLOC_USE_MMAP) {
-            rb_raise(rb_eNotImpError, "Compaction isn't available on this platform");
-        }
-#endif
-
-#if !GC_CAN_COMPILE_COMPACTION
-        rb_raise(rb_eNotImpError, "Compaction isn't available on this platform");
-#endif
+        GC_ASSERT(GC_COMPACTION_SUPPORTED);
 
         reason |= GPR_FLAG_COMPACT;
     }
@@ -9742,7 +9740,6 @@ gc_move(rb_objspace_t *objspace, VALUE scan, VALUE free, size_t src_slot_size, s
     return (VALUE)src;
 }
 
-#if GC_CAN_COMPILE_COMPACTION
 static int
 compare_free_slots(const void *left, const void *right, void *dummy)
 {
@@ -9791,7 +9788,6 @@ gc_sort_heap_by_empty_slots(rb_objspace_t *objspace)
         free(page_list);
     }
 }
-#endif
 
 static void
 gc_ref_update_array(rb_objspace_t * objspace, VALUE v)
@@ -10491,7 +10487,6 @@ gc_update_references(rb_objspace_t *objspace)
     gc_update_table_refs(objspace, finalizer_table);
 }
 
-#if GC_CAN_COMPILE_COMPACTION
 /*
  *  call-seq:
  *     GC.latest_compact_info -> {:considered=>{:T_CLASS=>11}, :moved=>{:T_CLASS=>11}}
@@ -10540,11 +10535,7 @@ gc_compact_stats(VALUE self)
 
     return h;
 }
-#else
-#  define gc_compact_stats rb_f_notimplement
-#endif
 
-#if GC_CAN_COMPILE_COMPACTION
 static void
 root_obj_check_moved_i(const char *category, VALUE obj, void *data)
 {
@@ -10619,11 +10610,7 @@ gc_compact(VALUE self)
 
     return gc_compact_stats(self);
 }
-#else
-#  define gc_compact rb_f_notimplement
-#endif
 
-#if GC_CAN_COMPILE_COMPACTION
 static VALUE
 gc_verify_compaction_references(rb_execution_context_t *ec, VALUE self, VALUE double_heap, VALUE toward_empty)
 {
@@ -10657,9 +10644,6 @@ gc_verify_compaction_references(rb_execution_context_t *ec, VALUE self, VALUE do
 
     return gc_compact_stats(self);
 }
-#else
-#  define gc_verify_compaction_references (rb_builtin_arity2_function_type)rb_f_notimplement
-#endif
 
 VALUE
 rb_gc_start(void)
@@ -11250,7 +11234,6 @@ gc_disable(rb_execution_context_t *ec, VALUE _)
     return rb_gc_disable();
 }
 
-#if GC_CAN_COMPILE_COMPACTION
 /*
  *  call-seq:
  *     GC.auto_compact = flag
@@ -11264,22 +11247,12 @@ gc_disable(rb_execution_context_t *ec, VALUE _)
 static VALUE
 gc_set_auto_compact(VALUE _, VALUE v)
 {
-    /* 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)
-    if (!HEAP_PAGE_ALLOC_USE_MMAP) {
-        rb_raise(rb_eNotImpError, "Automatic compaction isn't available on this platform");
-    }
-#endif
+    GC_ASSERT(GC_COMPACTION_SUPPORTED);
 
     ruby_enable_autocompact = RTEST(v);
     return v;
 }
-#else
-#  define gc_set_auto_compact rb_f_notimplement
-#endif
 
-#if GC_CAN_COMPILE_COMPACTION
 /*
  *  call-seq:
  *     GC.auto_compact    -> true or false
@@ -11291,9 +11264,6 @@ gc_get_auto_compact(VALUE _)
 {
     return RBOOL(ruby_enable_autocompact);
 }
-#else
-#  define gc_get_auto_compact rb_f_notimplement
-#endif
 
 static int
 get_envparam_size(const char *name, size_t *default_value, size_t lower_bound)
@@ -14150,13 +14120,21 @@ Init_GC(void)
     rb_define_singleton_method(rb_mGC, "malloc_allocated_size", gc_malloc_allocated_size, 0);
     rb_define_singleton_method(rb_mGC, "malloc_allocations", gc_malloc_allocations, 0);
 #endif
-    rb_define_singleton_method(rb_mGC, "compact", gc_compact, 0);
-    rb_define_singleton_method(rb_mGC, "auto_compact", gc_get_auto_compact, 0);
-    rb_define_singleton_method(rb_mGC, "auto_compact=", gc_set_auto_compact, 1);
-    rb_define_singleton_method(rb_mGC, "latest_compact_info", gc_compact_stats, 0);
-#if !GC_CAN_COMPILE_COMPACTION
-    rb_define_singleton_method(rb_mGC, "verify_compaction_references", rb_f_notimplement, -1);
-#endif
+
+    if (GC_COMPACTION_SUPPORTED) {
+        rb_define_singleton_method(rb_mGC, "compact", gc_compact, 0);
+        rb_define_singleton_method(rb_mGC, "auto_compact", gc_get_auto_compact, 0);
+        rb_define_singleton_method(rb_mGC, "auto_compact=", gc_set_auto_compact, 1);
+        rb_define_singleton_method(rb_mGC, "latest_compact_info", gc_compact_stats, 0);
+    }
+    else {
+        rb_define_singleton_method(rb_mGC, "compact", rb_f_notimplement, 0);
+        rb_define_singleton_method(rb_mGC, "auto_compact", rb_f_notimplement, 0);
+        rb_define_singleton_method(rb_mGC, "auto_compact=", rb_f_notimplement, 1);
+        rb_define_singleton_method(rb_mGC, "latest_compact_info", rb_f_notimplement, 0);
+        /* When !GC_COMPACTION_SUPPORTED, this method is not defined in gc.rb */
+        rb_define_singleton_method(rb_mGC, "verify_compaction_references", rb_f_notimplement, -1);
+    }
 
 #if GC_DEBUG_STRESS_TO_CLASS
     rb_define_singleton_method(rb_mGC, "add_stress_to_class", rb_gcdebug_add_stress_to_class, -1);
@@ -14180,7 +14158,7 @@ Init_GC(void)
 	OPT(MALLOC_ALLOCATED_SIZE);
 	OPT(MALLOC_ALLOCATED_SIZE_CHECK);
 	OPT(GC_PROFILE_DETAIL_MEMORY);
-	OPT(GC_CAN_COMPILE_COMPACTION);
+	OPT(GC_COMPACTION_SUPPORTED);
 #undef OPT
 	OBJ_FREEZE(opts);
     }