From cb6ff9e4198c6cd5abd915e271ea33d50f48b3d8 Mon Sep 17 00:00:00 2001 From: Steve Baird Date: Tue, 26 Jul 2022 17:17:17 -0700 Subject: [PATCH] [Ada] Single-element Append performance improvement Ada.Containers.Vectors has two Append procedures that take an Element value; one takes a Count parameter and one does not (the count is implicitly one for the latter). For the former version, there was code that took a faster path if certain conditions were met and otherwise took a slower path; one of the prerequisite conditions for this was Count = 1. For the latter version, no such special-case detection was performed; the more general code was always executed. Move the special-case detection/handling code from the former version into the latter and change the former version to simply call the latter version if Count = 1. Also apply same change to Ada.Containers.Indefinite_Vectors. gcc/ada/ * libgnat/a-coinve.adb, libgnat/a-convec.adb (Append): If the Append that takes an Element and a Count is called with Count = 1, then call the Append that does not take a Count parameter; otherwise call the code that handles the general case. Move the special case detection/handling code that was formerly in that version of Append into the version that does not take a Count parameter, so that now both versions get the performance benefit. --- gcc/ada/libgnat/a-coinve.adb | 41 +++++++++++++++++++++----------------- gcc/ada/libgnat/a-convec.adb | 47 ++++++++++++++++++++++++-------------------- 2 files changed, 49 insertions(+), 39 deletions(-) diff --git a/gcc/ada/libgnat/a-coinve.adb b/gcc/ada/libgnat/a-coinve.adb index c84175a..46d6730 100644 --- a/gcc/ada/libgnat/a-coinve.adb +++ b/gcc/ada/libgnat/a-coinve.adb @@ -197,12 +197,29 @@ is Count : Count_Type) is begin - -- In the general case, we pass the buck to Insert, but for efficiency, - -- we check for the usual case where Count = 1 and the vector has enough - -- room for at least one more element. + -- In the general case, we take the slow path; for efficiency, + -- we check for the common case where Count = 1 . - if Count = 1 - and then Container.Elements /= null + if Count = 1 then + Append (Container, New_Item); + else + Append_Slow_Path (Container, New_Item, Count); + end if; + end Append; + + ------------ + -- Append -- + ------------ + + procedure Append (Container : in out Vector; + New_Item : Element_Type) + is + begin + -- For performance, check for the common special case where the + -- container already has room for at least one more element. + -- In the general case, pass the buck to Insert. + + if Container.Elements /= null and then Container.Last /= Container.Elements.Last then TC_Check (Container.TC); @@ -223,23 +240,11 @@ is Container.Elements.EA (New_Last) := new Element_Type'(New_Item); Container.Last := New_Last; end; - else - Append_Slow_Path (Container, New_Item, Count); + Insert (Container, Last_Index (Container) + 1, New_Item, 1); end if; end Append; - ------------ - -- Append -- - ------------ - - procedure Append (Container : in out Vector; - New_Item : Element_Type) - is - begin - Insert (Container, Last_Index (Container) + 1, New_Item, 1); - end Append; - ---------------------- -- Append_Slow_Path -- ---------------------- diff --git a/gcc/ada/libgnat/a-convec.adb b/gcc/ada/libgnat/a-convec.adb index 3a2adae..751d468 100644 --- a/gcc/ada/libgnat/a-convec.adb +++ b/gcc/ada/libgnat/a-convec.adb @@ -173,27 +173,11 @@ is Count : Count_Type) is begin - -- In the general case, we pass the buck to Insert, but for efficiency, - -- we check for the usual case where Count = 1 and the vector has enough - -- room for at least one more element. - - if Count = 1 - and then Container.Elements /= null - and then Container.Last /= Container.Elements.Last - then - TC_Check (Container.TC); - - -- Increment Container.Last after assigning the New_Item, so we - -- leave the Container unmodified in case Finalize/Adjust raises - -- an exception. - - declare - New_Last : constant Index_Type := Container.Last + 1; - begin - Container.Elements.EA (New_Last) := New_Item; - Container.Last := New_Last; - end; + -- In the general case, we take the slow path; for efficiency, + -- we check for the common case where Count = 1 . + if Count = 1 then + Append (Container, New_Item); else Append_Slow_Path (Container, New_Item, Count); end if; @@ -222,7 +206,28 @@ is New_Item : Element_Type) is begin - Insert (Container, Last_Index (Container) + 1, New_Item, 1); + -- For performance, check for the common special case where the + -- container already has room for at least one more element. + -- In the general case, pass the buck to Insert. + + if Container.Elements /= null + and then Container.Last /= Container.Elements.Last + then + TC_Check (Container.TC); + + -- Increment Container.Last after assigning the New_Item, so we + -- leave the Container unmodified in case Finalize/Adjust raises + -- an exception. + + declare + New_Last : constant Index_Type := Container.Last + 1; + begin + Container.Elements.EA (New_Last) := New_Item; + Container.Last := New_Last; + end; + else + Insert (Container, Last_Index (Container) + 1, New_Item, 1); + end if; end Append; ---------------------- -- 2.7.4