In earlier work, a performance problem was addressed by rewriting Ada.Containers.Doubly_Linked_Lists.Generic_Sorting in a-cdlili.adb. It turned out that the very-slow-in-some-cases Sort algorithm formerly used there was duplicated in 4 other units: the Bounded, Formal, Indefinite, and Restricted versions. With this change, we use the better sorting algorithm in all 5 cases while reducing code duplication.
Tested on x86_64-pc-linux-gnu, committed on trunk gcc/ada/ * libgnat/a-costso.ads, libgnat/a-costso.adb: A new library unit, Ada.Containers.Stable_Sorting, which exports a pair of generics (one within the other) which are instantiated by each of the 5 doubly-linked list container generics to implement their respective Sort procedures. We use a pair of generics, rather than a single generic, in order to further reduce code duplication. The outer generic takes a formal private Node_Ref type representing a reference to a linked list element. For some instances, the corresponding actual parameter will be an access type; for others, it will be the index type for an array. * Makefile.rtl: Include new Ada.Containers.Stable_Sorting unit. * libgnat/a-cbdlli.adb, libgnat/a-cdlili.adb, libgnat/a-cfdlli.adb, libgnat/a-cidlli.adb, libgnat/a-crdlli.adb (Sort): Replace existing Sort implementation with a call to an instance of Ada.Containers.Stable_Sorting.Doubly_Linked_List_Sort. Declare the (trivial) actual parameters needed to declare that instance. * libgnat/a-cfdlli.ads: Fix a bug encountered during testing in the postcondition for M_Elements_Sorted. With a partial ordering, it is possible for all three of (X < Y), (Y < X), and (X = Y) to be simultaneously false, so that case needs to handled correctly.
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