https://gcc.gnu.org/g:f6a8c07743d74430da761e3ca7a8516ac663ef94
commit r15-4923-gf6a8c07743d74430da761e3ca7a8516ac663ef94
Author: Nicolas Roche <ro...@adacore.com>
Date: Wed Oct 16 11:56:35 2024 +0200
ada: Improve Unbounded_Wide_String performance
Improve performance of iteration using Element function.
Improve performance of Append.
gcc/ada/ChangeLog:
* libgnat/a-stwiun__shared.adb: Restructure code to inline only
the most common cases. Remove whenever possible runtime checks.
* libgnat/a-stwiun__shared.ads: Add Inline => True to Append
variants and Element.
Diff:
---
gcc/ada/libgnat/a-stwiun__shared.adb | 164 ++++++++++++++++++++++++++---------
gcc/ada/libgnat/a-stwiun__shared.ads | 9 +-
2 files changed, 127 insertions(+), 46 deletions(-)
diff --git a/gcc/ada/libgnat/a-stwiun__shared.adb
b/gcc/ada/libgnat/a-stwiun__shared.adb
index 26b4f8ec85fa..d3f20f0af20e 100644
--- a/gcc/ada/libgnat/a-stwiun__shared.adb
+++ b/gcc/ada/libgnat/a-stwiun__shared.adb
@@ -36,7 +36,24 @@ package body Ada.Strings.Wide_Unbounded is
use Ada.Strings.Wide_Maps;
- Growth_Factor : constant := 32;
+ procedure Non_Inlined_Append
+ (Source : in out Unbounded_Wide_String;
+ New_Item : Unbounded_Wide_String);
+
+ procedure Non_Inlined_Append
+ (Source : in out Unbounded_Wide_String;
+ New_Item : Wide_String);
+
+ procedure Non_Inlined_Append
+ (Source : in out Unbounded_Wide_String;
+ New_Item : Wide_Character);
+ -- Non_Inlined_Append are part of the respective Append method that
+ -- should not be inlined. The idea is that the code of Append is inlined.
+ -- In order to make inlining efficient it is better to have the inlined
+ -- code as small as possible. Thus most common cases are inlined and less
+ -- common cases are deferred in these functions.
+
+ Growth_Factor : constant := 2;
-- The growth factor controls how much extra space is allocated when
-- we have to increase the size of an allocated unbounded string. By
-- allocating extra space, we avoid the need to reallocate on every
@@ -525,10 +542,12 @@ package body Ada.Strings.Wide_Unbounded is
(Source : in out Unbounded_Wide_String;
New_Item : Unbounded_Wide_String)
is
+ pragma Suppress (All_Checks);
+ -- Suppress checks as they are redundant with the checks done in that
+ -- function.
+
SR : constant Shared_Wide_String_Access := Source.Reference;
NR : constant Shared_Wide_String_Access := New_Item.Reference;
- DL : constant Natural := SR.Last + NR.Last;
- DR : Shared_Wide_String_Access;
begin
-- Source is an empty string, reuse New_Item data
@@ -545,19 +564,17 @@ package body Ada.Strings.Wide_Unbounded is
-- Try to reuse existent shared string
- elsif Can_Be_Reused (SR, DL) then
- SR.Data (SR.Last + 1 .. DL) := NR.Data (1 .. NR.Last);
- SR.Last := DL;
+ elsif System.Atomic_Counters.Is_One (SR.Counter)
+ and then NR.Last <= SR.Max_Length
+ and then SR.Max_Length - NR.Last >= SR.Last
+ then
+ SR.Data (SR.Last + 1 .. SR.Last + NR.Last) := NR.Data (1 .. NR.Last);
+ SR.Last := SR.Last + NR.Last;
-- Otherwise, allocate new one and fill it
else
- DR := Allocate (DL + DL / Growth_Factor);
- DR.Data (1 .. SR.Last) := SR.Data (1 .. SR.Last);
- DR.Data (SR.Last + 1 .. DL) := NR.Data (1 .. NR.Last);
- DR.Last := DL;
- Source.Reference := DR;
- Unreference (SR);
+ Non_Inlined_Append (Source, New_Item);
end if;
end Append;
@@ -565,31 +582,34 @@ package body Ada.Strings.Wide_Unbounded is
(Source : in out Unbounded_Wide_String;
New_Item : Wide_String)
is
- SR : constant Shared_Wide_String_Access := Source.Reference;
- DL : constant Natural := SR.Last + New_Item'Length;
- DR : Shared_Wide_String_Access;
+ pragma Suppress (All_Checks);
+ -- Suppress checks as they are redundant with the checks done in that
+ -- function.
+ New_Item_Length : constant Natural := New_Item'Length;
+ SR : constant Shared_Wide_String_Access := Source.Reference;
begin
- -- New_Item is an empty string, nothing to do
if New_Item'Length = 0 then
+ -- New_Item is an empty string, nothing to do
null;
- -- Try to reuse existing shared string
-
- elsif Can_Be_Reused (SR, DL) then
- SR.Data (SR.Last + 1 .. DL) := New_Item;
- SR.Last := DL;
-
- -- Otherwise, allocate new one and fill it
+ elsif System.Atomic_Counters.Is_One (SR.Counter)
+ -- The following test checks in fact that
+ -- SR.Max_Length >= SR.Last + New_Item_Length without causing
+ -- overflow.
+ and then New_Item_Length <= SR.Max_Length
+ and then SR.Max_Length - New_Item_Length >= SR.Last
+ then
+ -- Try to reuse existing shared string
+ SR.Data (SR.Last + 1 .. SR.Last + New_Item_Length) := New_Item;
+ SR.Last := SR.Last + New_Item_Length;
else
- DR := Allocate (DL + DL / Growth_Factor);
- DR.Data (1 .. SR.Last) := SR.Data (1 .. SR.Last);
- DR.Data (SR.Last + 1 .. DL) := New_Item;
- DR.Last := DL;
- Source.Reference := DR;
- Unreference (SR);
+ -- Otherwise, allocate new one and fill it. Deferring the worst case
+ -- into a separate non-inlined function ensure that inlined Append
+ -- code size remains short and thus efficient.
+ Non_Inlined_Append (Source, New_Item);
end if;
end Append;
@@ -597,26 +617,24 @@ package body Ada.Strings.Wide_Unbounded is
(Source : in out Unbounded_Wide_String;
New_Item : Wide_Character)
is
- SR : constant Shared_Wide_String_Access := Source.Reference;
- DL : constant Natural := SR.Last + 1;
- DR : Shared_Wide_String_Access;
+ pragma Suppress (All_Checks);
+ -- Suppress checks as they are redundant with the checks done in that
+ -- function.
+ SR : constant Shared_Wide_String_Access := Source.Reference;
begin
- -- Try to reuse existing shared string
-
- if Can_Be_Reused (SR, SR.Last + 1) then
+ if System.Atomic_Counters.Is_One (SR.Counter)
+ and then SR.Max_Length > SR.Last
+ then
+ -- Try to reuse existing shared string
SR.Data (SR.Last + 1) := New_Item;
SR.Last := SR.Last + 1;
- -- Otherwise, allocate new one and fill it
-
else
- DR := Allocate (DL + DL / Growth_Factor);
- DR.Data (1 .. SR.Last) := SR.Data (1 .. SR.Last);
- DR.Data (DL) := New_Item;
- DR.Last := DL;
- Source.Reference := DR;
- Unreference (SR);
+ -- Otherwise, allocate new one and fill it. Deferring the worst case
+ -- into a separate non-inlined function ensure that inlined Append
+ -- code size remains short and thus efficient.
+ Non_Inlined_Append (Source, New_Item);
end if;
end Append;
@@ -1178,6 +1196,66 @@ package body Ada.Strings.Wide_Unbounded is
return Source.Reference.Last;
end Length;
+ ------------------------
+ -- Non_Inlined_Append --
+ ------------------------
+
+ procedure Non_Inlined_Append
+ (Source : in out Unbounded_Wide_String;
+ New_Item : Unbounded_Wide_String)
+ is
+ SR : constant Shared_Wide_String_Access := Source.Reference;
+ NR : constant Shared_Wide_String_Access := New_Item.Reference;
+ DL : constant Natural := SR.Last + NR.Last;
+ DR : Shared_Wide_String_Access;
+ begin
+ DR := Allocate (DL + DL / Growth_Factor);
+ DR.Data (1 .. SR.Last) := SR.Data (1 .. SR.Last);
+ DR.Data (SR.Last + 1 .. DL) := NR.Data (1 .. NR.Last);
+ DR.Last := DL;
+ Source.Reference := DR;
+ Unreference (SR);
+ end Non_Inlined_Append;
+
+ procedure Non_Inlined_Append
+ (Source : in out Unbounded_Wide_String;
+ New_Item : Wide_String)
+ is
+ SR : constant Shared_Wide_String_Access := Source.Reference;
+ DL : constant Natural := SR.Last + New_Item'Length;
+ DR : Shared_Wide_String_Access;
+ begin
+ DR := Allocate (DL + DL / Growth_Factor);
+ DR.Data (1 .. SR.Last) := SR.Data (1 .. SR.Last);
+ DR.Data (SR.Last + 1 .. DL) := New_Item;
+ DR.Last := DL;
+ Source.Reference := DR;
+ Unreference (SR);
+ end Non_Inlined_Append;
+
+ procedure Non_Inlined_Append
+ (Source : in out Unbounded_Wide_String;
+ New_Item : Wide_Character)
+ is
+ SR : constant Shared_Wide_String_Access := Source.Reference;
+ begin
+ if SR.Last = Natural'Last then
+ raise Constraint_Error;
+ else
+ declare
+ DL : constant Natural := SR.Last + 1;
+ DR : Shared_Wide_String_Access;
+ begin
+ DR := Allocate (DL + DL / Growth_Factor);
+ DR.Data (1 .. SR.Last) := SR.Data (1 .. SR.Last);
+ DR.Data (DL) := New_Item;
+ DR.Last := DL;
+ Source.Reference := DR;
+ Unreference (SR);
+ end;
+ end if;
+ end Non_Inlined_Append;
+
---------------
-- Overwrite --
---------------
diff --git a/gcc/ada/libgnat/a-stwiun__shared.ads
b/gcc/ada/libgnat/a-stwiun__shared.ads
index 865970f052cf..19ccebf71869 100644
--- a/gcc/ada/libgnat/a-stwiun__shared.ads
+++ b/gcc/ada/libgnat/a-stwiun__shared.ads
@@ -79,15 +79,18 @@ package Ada.Strings.Wide_Unbounded is
procedure Append
(Source : in out Unbounded_Wide_String;
- New_Item : Unbounded_Wide_String);
+ New_Item : Unbounded_Wide_String)
+ with Inline => True;
procedure Append
(Source : in out Unbounded_Wide_String;
- New_Item : Wide_String);
+ New_Item : Wide_String)
+ with Inline => True;
procedure Append
(Source : in out Unbounded_Wide_String;
- New_Item : Wide_Character);
+ New_Item : Wide_Character)
+ with Inline => True;
function "&"
(Left : Unbounded_Wide_String;
