rsx: Fix insertion of execution barriers

- Ignore barriers inserted after BEGIN but before any draw commands are emitted
- Properly process tail barriers inserted before END but after draw commands are submitted
- Ignore execution barriers with no effect (same register value written)

rpcs3/Emu/RSX/GL/GLGSRender.cpp

@@ -623,6 +623,8 @@ void GLGSRender::end()
 		}
 	} while (rsx::method_registers.current_draw_clause.next());
 
+	rsx::method_registers.current_draw_clause.post_execute_cleanup();
+
 	m_rtts.on_write();
 
 	m_attrib_ring_buffer->notify();

rpcs3/Emu/RSX/VK/VKGSRender.cpp

@@ -1682,6 +1682,8 @@ void VKGSRender::end()
 	}
 	while (rsx::method_registers.current_draw_clause.next());
 
+	rsx::method_registers.current_draw_clause.post_execute_cleanup();
+
 	close_render_pass();
 	vk::leave_uninterruptible();
 

rpcs3/Emu/RSX/rsx_methods.cpp

@@ -632,7 +632,9 @@ namespace rsx
 
 		void set_vertex_base_offset(thread* rsx, u32 reg, u32 arg)
 		{
-			if (rsx->in_begin_end)
+			if (rsx->in_begin_end &&
+				!rsx::method_registers.current_draw_clause.empty() &&
+				reg != method_registers.register_previous_value)
 			{
 				// Revert change to queue later
 				method_registers.decode(reg, method_registers.register_previous_value);
@@ -644,7 +646,9 @@ namespace rsx
 
 		void set_index_base_offset(thread* rsx, u32 reg, u32 arg)
 		{
-			if (rsx->in_begin_end)
+			if (rsx->in_begin_end &&
+				!rsx::method_registers.current_draw_clause.empty() &&
+				reg != method_registers.register_previous_value)
 			{
 				// Revert change to queue later
 				method_registers.decode(reg, method_registers.register_previous_value);

rpcs3/Emu/RSX/rsx_methods.h

@@ -277,7 +277,7 @@ namespace rsx
 
 		bool empty() const
 		{
-			return (draw_command_ranges.empty() && inline_vertex_array.empty());
+			return (command == rsx::draw_command::inlined_array) ? inline_vertex_array.empty() : draw_command_ranges.empty();
 		}
 
 		u32 pass_count() const
@@ -288,7 +288,15 @@ namespace rsx
 				return 1u;
 			}
 
-			return (u32)draw_command_ranges.size();
+			u32 count = (u32)draw_command_ranges.size();
+			if (draw_command_ranges.back().count == 0)
+			{
+				// Dangling barrier
+				verify(HERE), count > 1;
+				count--;
+			}
+
+			return count;
 		}
 
 		void reset(rsx::primitive_type type)
@@ -339,10 +347,36 @@ namespace rsx
 				return false;
 			}
 
-			verify(HERE), draw_command_ranges[current_range_index].count != 0;
+			if (draw_command_ranges[current_range_index].count == 0)
+			{
+				// Dangling execution barrier
+				verify(HERE), current_range_index > 0 && (current_range_index + 1) == draw_command_ranges.size();
+				current_range_index = 0;
+				return false;
+			}
+
 			return true;
 		}
 
+		/**
+		 * Only call this once after the draw clause has been fully consumed to reconcile any conflicts
+		 */
+		void post_execute_cleanup()
+		{
+			verify(HERE), current_range_index == 0;
+
+			if (draw_command_ranges.size() > 1)
+			{
+				if (draw_command_ranges.back().count == 0)
+				{
+					// Dangling execution barrier
+					current_range_index = draw_command_ranges.size() - 1;
+					execute_pipeline_dependencies();
+					current_range_index = 0;
+				}
+			}
+		}
+
 		/**
 		 * Executes commands reqiured to make the current draw state valid
 		 */