Enable delegate .ctor optimization under sgen.

	* method-to-ir.c (handle_delegate_ctor): Emit write barriers
	under sgen.

	* method-to-ir.c (mono_method_to_ir): Enable delegate .ctor
	optimization under sgen.

mono/mini/method-to-ir.c

@@ -3670,6 +3670,8 @@ handle_ccastclass (MonoCompile *cfg, MonoClass *klass, MonoInst *src)
 static G_GNUC_UNUSED MonoInst*
 handle_delegate_ctor (MonoCompile *cfg, MonoClass *klass, MonoInst *target, MonoMethod *method, int context_used)
 {
+	MonoInst *ptr;
+	int dreg;
 	gpointer *trampoline;
 	MonoInst *obj, *method_ins, *tramp_ins;
 	MonoDomain *domain;
@@ -3683,13 +3685,23 @@ handle_delegate_ctor (MonoCompile *cfg, MonoClass *klass, MonoInst *target, Mono
 
 	/* Set target field */
 	/* Optimize away setting of NULL target */
-	if (!(target->opcode == OP_PCONST && target->inst_p0 == 0))
+	if (!(target->opcode == OP_PCONST && target->inst_p0 == 0)) {
 		MONO_EMIT_NEW_STORE_MEMBASE (cfg, OP_STORE_MEMBASE_REG, obj->dreg, G_STRUCT_OFFSET (MonoDelegate, target), target->dreg);
+		if (cfg->gen_write_barriers) {
+			dreg = alloc_preg (cfg);
+			EMIT_NEW_BIALU_IMM (cfg, ptr, OP_PADD_IMM, dreg, obj->dreg, G_STRUCT_OFFSET (MonoDelegate, target));
+			emit_write_barrier (cfg, ptr, target, 0);
+		}
+	}
 
 	/* Set method field */
 	method_ins = emit_get_rgctx_method (cfg, context_used, method, MONO_RGCTX_INFO_METHOD);
 	MONO_EMIT_NEW_STORE_MEMBASE (cfg, OP_STORE_MEMBASE_REG, obj->dreg, G_STRUCT_OFFSET (MonoDelegate, method), method_ins->dreg);
-
+	if (cfg->gen_write_barriers) {
+		dreg = alloc_preg (cfg);
+		EMIT_NEW_BIALU_IMM (cfg, ptr, OP_PADD_IMM, dreg, obj->dreg, G_STRUCT_OFFSET (MonoDelegate, method));
+		emit_write_barrier (cfg, ptr, method_ins, 0);
+	}
 	/* 
 	 * To avoid looking up the compiled code belonging to the target method
 	 * in mono_delegate_trampoline (), we allocate a per-domain memory slot to
@@ -9667,7 +9679,7 @@ mono_method_to_ir (MonoCompile *cfg, MonoMethod *method, MonoBasicBlock *start_b
 
 #if defined(MONO_ARCH_HAVE_CREATE_DELEGATE_TRAMPOLINE)
 						/* FIXME: SGEN support */
-						if (!cfg->gen_write_barriers && invoke_context_used == 0) {
+						if (invoke_context_used == 0) {
 							ip += 6;
 							if (cfg->verbose_level > 3)
 								g_print ("converting (in B%d: stack: %d) %s", bblock->block_num, (int)(sp - stack_start), mono_disasm_code_one (NULL, method, ip, NULL));