ada: Improve efficiency of scope stack restoration

We save/restore visibility by setting the Is_Immediately_Visible flag
and appending entities to / removing them from the tail of an element
list.

However, the Is_Immediately_Visible flag can be restored in any order,
while the element list is singly-linked and removal from the tail is
inefficient. This change removes a performance hot spot, which accounted
for up to 10% of compilation time of complex applications (e.g. QGen),
at least as measured on GNAT built with profiling support.

gcc/ada/

	* sem_ch8.adb (Restore_Scope_Stack): Remove elements from the head
	and not the tail of an element list.

0 files changed, 0 insertions, 0 deletions