[mbr] Add a global has_updates flag

src/mono/mono/metadata/metadata-internals.h

@@ -910,20 +910,37 @@ void
 mono_image_append_class_to_reflection_info_set (MonoClass *klass);
 
 #ifndef ENABLE_METADATA_UPDATE
+static inline gboolean
+mono_metadata_has_updates (void)
+{
+	return FALSE;
+}
+
 static inline void
 mono_image_effective_table (const MonoTableInfo **t, int *idx)
 {
 }
 #else /* ENABLE_METADATA_UPDATE */
+extern int mono_metadata_update_has_updates_private;
+
+/* returns TRUE if there's at least one update */
+static inline gboolean
+mono_metadata_has_updates (void)
+{
+	return mono_metadata_update_has_updates_private != 0;
+}
+
 void
 mono_image_effective_table_slow (const MonoTableInfo **t, int *idx);
 
 static inline void
 mono_image_effective_table (const MonoTableInfo **t, int *idx)
 {
-	if (G_LIKELY (*idx < (*t)->rows))
-		return;
-	mono_image_effective_table_slow (t, idx);
+	if (G_UNLIKELY (mono_metadata_has_updates ())) {
+		if (G_UNLIKELY (*idx >= (*t)->rows)) {
+			mono_image_effective_table_slow (t, idx);
+		}
+	}
 }
 
 int

src/mono/mono/metadata/metadata-update.c

@@ -32,6 +32,11 @@ static MonoNativeTlsKey exposed_generation_id;
 #define UPDATE_DEBUG(stmt) /*empty */
 #endif
 
+/*
+ * set to non-zero if at least one update has been published.
+ */
+int mono_metadata_update_has_updates_private;
+
 /* For each delta image, for each table:
  * - the total logical number of rows for the previous generation
  * - the number of modified rows in the current generation
@@ -172,6 +177,7 @@ metadata_update_local_generation (MonoImage *base, MonoImage *delta);
 void
 mono_metadata_update_init (void)
 {
+	mono_metadata_update_has_updates_private = 0;
 	table_to_image_init ();
 	mono_native_tls_alloc (&exposed_generation_id, NULL);
 }
@@ -232,6 +238,15 @@ thread_set_exposed_generation (uint32_t value)
 	mono_native_tls_set_value (exposed_generation_id, GUINT_TO_POINTER((guint)value));
 }
 
+/**
+ * LOCKING: assumes the publish_lock is held
+ */
+static void
+metadata_update_set_has_updates (void)
+{
+	mono_metadata_update_has_updates_private = 1;
+}
+
 uint32_t
 mono_metadata_update_prepare (MonoDomain *domain) {
 	mono_lazy_initialize (&metadata_update_lazy_init, initialize);
@@ -240,6 +255,8 @@ mono_metadata_update_prepare (MonoDomain *domain) {
 	 */
 	publish_lock ();
 	uint32_t alloc_gen = ++update_alloc_frontier;
+	/* Have to set this here so the updater starts using the slow path of metadata lookups */
+	metadata_update_set_has_updates ();
 	/* Expose the alloc frontier to the updater thread */
 	thread_set_exposed_generation (alloc_gen);
 	return alloc_gen;
@@ -320,6 +337,7 @@ mono_image_append_delta (MonoImage *base, MonoImage *delta)
 		return;
 	}
 	g_assert (((MonoImage*)base->delta_image_last->data)->generation < delta->generation);
+	/* FIXME: g_list_append returns the previous end of the list, not the newly appended element! */
 	base->delta_image_last = g_list_append (base->delta_image_last, delta);
 }
 

src/mono/mono/metadata/metadata.c

@@ -1339,6 +1339,9 @@ dword_align (const unsigned char *ptr)
 	return (const unsigned char *) (((gsize) (ptr + 3)) & ~3);
 }
 
+static void
+mono_metadata_decode_row_slow (const MonoTableInfo *t, int idx, guint32 *res, int res_size);
+
 /**
  * mono_metadata_decode_row:
  * \param t table to extract information from.
@@ -1351,8 +1354,17 @@ dword_align (const unsigned char *ptr)
 void
 mono_metadata_decode_row (const MonoTableInfo *t, int idx, guint32 *res, int res_size)
 {
-	mono_image_effective_table (&t, &idx);
+	if (G_UNLIKELY (mono_metadata_has_updates ())) {
+		mono_metadata_decode_row_slow (t, idx, res, res_size);
+	} else {
+		mono_metadata_decode_row_raw (t, idx, res, res_size);
+	}
+}
 
+void
+mono_metadata_decode_row_slow (const MonoTableInfo *t, int idx, guint32 *res, int res_size)
+{
+	mono_image_effective_table (&t, &idx);
 	mono_metadata_decode_row_raw (t, idx, res, res_size);
 }
 
@@ -1470,6 +1482,11 @@ mono_metadata_decode_row_dynamic_checked (const MonoDynamicImage *image, const M
 	return TRUE;
 }
 
+static guint32
+mono_metadata_decode_row_col_raw (const MonoTableInfo *t, int idx, guint col);
+static guint32
+mono_metadata_decode_row_col_slow (const MonoTableInfo *t, int idx, guint col);
+
 /**
  * mono_metadata_decode_row_col:
  * \param t table to extract information from.
@@ -1481,13 +1498,34 @@ mono_metadata_decode_row_dynamic_checked (const MonoDynamicImage *image, const M
  */
 guint32
 mono_metadata_decode_row_col (const MonoTableInfo *t, int idx, guint col)
+{
+	if (G_UNLIKELY (mono_metadata_has_updates ())) {
+		return mono_metadata_decode_row_col_slow (t, idx, col);
+	} else {
+		return mono_metadata_decode_row_col_raw (t, idx, col);
+	}
+}
+
+guint32
+mono_metadata_decode_row_col_slow (const MonoTableInfo *t, int idx, guint col)
+{
+	mono_image_effective_table (&t, &idx);
+	return mono_metadata_decode_row_col_raw (t, idx, col);
+}
+
+/**
+ * mono_metadata_decode_row_col_raw:
+ *
+ * Same as \c mono_metadata_decode_row_col but doesn't look for the effective
+ * table on metadata updates.
+ */
+guint32
+mono_metadata_decode_row_col_raw (const MonoTableInfo *t, int idx, guint col)
 {
 	int i;
 	const char *data;
 	int n;
 
-	mono_image_effective_table (&t, &idx);
-
 	guint32 bitfield = t->size_bitfield;
 
 	g_assert (idx < t->rows);