The frequently called Get_Source_File_Index function is optimized to
be inline and is now a simple array access. This is an internal
optimization only, with no functional effect (except hopefully
a compilation time speed up). No test required
Tested on x86_64-pc-linux-gnu, committed on trunk
2013-10-10 Robert Dewar <de...@adacore.com>
* sinput-c.adb (Load_File): Ensure Source_Align alignment.
* sinput-d.adb (Create_Debug_Source): Ensure Source_Align alignment.
* sinput-l.adb (Create_Instantiation_Source): Ensure Source_Align
alignment.
(Load_File): Ditto.
* sinput.ads, sinput.adb (Get_Source_File_Index): New optimized (single
line) version.
* types.ads (Source_Align): New definition.
(Source_Buffer): Document new alignment requirement.
Index: sinput-d.adb
===================================================================
--- sinput-d.adb (revision 203342)
+++ sinput-d.adb (working copy)
@@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
--- Copyright (C) 2002-2007, Free Software Foundation, Inc. --
+-- Copyright (C) 2002-2013, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
@@ -62,7 +62,9 @@
Loc : out Source_Ptr)
is
begin
- Loc := Source_File.Table (Source_File.Last).Source_Last + 1;
+ Loc :=
+ ((Source_File.Table (Source_File.Last).Source_Last + Source_Align) /
+ Source_Align) * Source_Align;
Source_File.Append (Source_File.Table (Source));
Dfile := Source_File.Last;
Index: types.ads
===================================================================
--- types.ads (revision 203342)
+++ types.ads (working copy)
@@ -183,11 +183,17 @@
No_Column_Number : constant Column_Number := 0;
-- Special value used to indicate no column number
+ Source_Align : constant := 2 ** 12;
+ -- Alignment requirement for source buffers (by keeping source buffers
+ -- aligned, we can optimize the implementation of Get_Source_File_Index.
+ -- See this routine in Sinput for details.
+
subtype Source_Buffer is Text_Buffer;
-- Type used to store text of a source file. The buffer for the main
-- source (the source specified on the command line) has a lower bound
-- starting at zero. Subsequent subsidiary sources have lower bounds
- -- which are one greater than the previous upper bound.
+ -- which are one greater than the previous upper bound, rounded up to
+ -- a multiple of Source_Align.
subtype Big_Source_Buffer is Text_Buffer (0 .. Text_Ptr'Last);
-- This is a virtual type used as the designated type of the access type
Index: sinput-l.adb
===================================================================
--- sinput-l.adb (revision 203342)
+++ sinput-l.adb (working copy)
@@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
--- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2013, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
@@ -112,7 +112,6 @@
procedure Complete_Source_File_Entry is
CSF : constant Source_File_Index := Current_Source_File;
-
begin
Trim_Lines_Table (CSF);
Source_File.Table (CSF).Source_Checksum := Checksum;
@@ -158,7 +157,6 @@
Snew.Inlined_Call := Sloc (Inst_Node);
else
-
-- If the spec has been instantiated already, and we are now
-- creating the instance source for the corresponding body now,
-- retrieve the instance id that was assigned to the spec, which
@@ -167,10 +165,10 @@
Inst_Spec := Instance_Spec (Inst_Node);
if Present (Inst_Spec) then
declare
- Inst_Spec_Ent : Entity_Id;
+ Inst_Spec_Ent : Entity_Id;
-- Instance spec entity
- Inst_Spec_Sloc : Source_Ptr;
+ Inst_Spec_Sloc : Source_Ptr;
-- Virtual sloc of the spec instance source
Inst_Spec_Inst_Id : Instance_Id;
@@ -188,12 +186,13 @@
-- The specification of the instance entity has a virtual
-- sloc within the instance sloc range.
+
-- ??? But the Unit_Declaration_Node has the sloc of the
-- instantiation, which is somewhat of an oddity.
- Inst_Spec_Sloc :=
- Sloc (Specification (Unit_Declaration_Node
- (Inst_Spec_Ent)));
+ Inst_Spec_Sloc :=
+ Sloc
+ (Specification (Unit_Declaration_Node (Inst_Spec_Ent)));
Inst_Spec_Inst_Id :=
Source_File.Table
(Get_Source_File_Index (Inst_Spec_Sloc)).Instance;
@@ -209,11 +208,16 @@
end if;
end if;
- -- Now we need to compute the new values of Source_First,
+ -- Now we need to compute the new values of Source_First and
-- Source_Last and adjust the source file pointer to have the
-- correct virtual origin for the new range of values.
- Snew.Source_First := Source_File.Table (Xnew - 1).Source_Last + 1;
+ -- Source_First must be greater than the last Source_Last value
+ -- and also must be a multiple of Source_Align
+
+ Snew.Source_First :=
+ ((Source_File.Table (Xnew - 1).Source_Last + Source_Align) /
+ Source_Align) * Source_Align;
A.Adjust := Snew.Source_First - A.Lo;
Snew.Source_Last := A.Hi + A.Adjust;
@@ -398,10 +402,13 @@
Source_File.Increment_Last;
X := Source_File.Last;
+ -- Compute starting index, respecting alignment requirement
+
if X = Source_File.First then
Lo := First_Source_Ptr;
else
- Lo := Source_File.Table (X - 1).Source_Last + 1;
+ Lo := ((Source_File.Table (X - 1).Source_Last + Source_Align) /
+ Source_Align) * Source_Align;
end if;
Osint.Read_Source_File (N, Lo, Hi, Src, T);
Index: sinput.adb
===================================================================
--- sinput.adb (revision 203342)
+++ sinput.adb (working copy)
@@ -434,44 +434,9 @@
-- Get_Source_File_Index --
---------------------------
- Source_Cache_First : Source_Ptr := 1;
- Source_Cache_Last : Source_Ptr := 0;
- -- Records the First and Last subscript values for the most recently
- -- referenced entry in the source table, to optimize the common case of
- -- repeated references to the same entry. The initial values force an
- -- initial search to set the cache value.
-
- Source_Cache_Index : Source_File_Index := No_Source_File;
- -- Contains the index of the entry corresponding to Source_Cache
-
function Get_Source_File_Index (S : Source_Ptr) return Source_File_Index is
begin
- if S in Source_Cache_First .. Source_Cache_Last then
- return Source_Cache_Index;
-
- else
- pragma Assert (Source_File_Index_Table (Int (S) / Chunk_Size)
- /=
- No_Source_File);
- for J in Source_File_Index_Table (Int (S) / Chunk_Size)
- .. Source_File.Last
- loop
- if S in Source_File.Table (J).Source_First ..
- Source_File.Table (J).Source_Last
- then
- Source_Cache_Index := J;
- Source_Cache_First :=
- Source_File.Table (Source_Cache_Index).Source_First;
- Source_Cache_Last :=
- Source_File.Table (Source_Cache_Index).Source_Last;
- return Source_Cache_Index;
- end if;
- end loop;
- end if;
-
- -- We must find a matching entry in the above loop!
-
- raise Program_Error;
+ return Source_File_Index_Table (Int (S) / Source_Align);
end Get_Source_File_Index;
----------------
@@ -480,9 +445,6 @@
procedure Initialize is
begin
- Source_Cache_First := 1;
- Source_Cache_Last := 0;
- Source_Cache_Index := No_Source_File;
Source_gnat_adc := No_Source_File;
First_Time_Around := True;
@@ -724,15 +686,13 @@
Ind : Int;
SP : Source_Ptr;
SL : constant Source_Ptr := Source_File.Table (Xnew).Source_Last;
-
begin
- SP := (Source_File.Table (Xnew).Source_First + Chunk_Size - 1)
- / Chunk_Size * Chunk_Size;
- Ind := Int (SP) / Chunk_Size;
-
+ SP := Source_File.Table (Xnew).Source_First;
+ pragma Assert (SP mod Source_Align = 0);
+ Ind := Int (SP) / Source_Align;
while SP <= SL loop
Source_File_Index_Table (Ind) := Xnew;
- SP := SP + Chunk_Size;
+ SP := SP + Source_Align;
Ind := Ind + 1;
end loop;
end Set_Source_File_Index_Table;
@@ -921,19 +881,14 @@
end loop;
end if;
- -- Reset source cache pointers to force new read
-
- Source_Cache_First := 1;
- Source_Cache_Last := 0;
-
-- Read in source file table and instance table
Source_File.Tree_Read;
Instances.Tree_Read;
- -- The pointers we read in there for the source buffer and lines
- -- table pointers are junk. We now read in the actual data that
- -- is referenced by these two fields.
+ -- The pointers we read in there for the source buffer and lines table
+ -- pointers are junk. We now read in the actual data that is referenced
+ -- by these two fields.
for J in Source_File.First .. Source_File.Last loop
declare
Index: sinput.ads
===================================================================
--- sinput.ads (revision 203342)
+++ sinput.ads (working copy)
@@ -6,7 +6,7 @@
-- --
-- S p e c --
-- --
--- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2013, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
@@ -342,36 +342,17 @@
-- The Get_Source_File_Index function is called very frequently. Earlier
-- versions cached a single entry, but then reverted to a serial search,
- -- and this proved to be a significant source of inefficiency. To get
- -- around this, we use the following directly indexed array. The space
- -- of possible input values is a value of type Source_Ptr which is simply
- -- an Int value. The values in this space are allocated sequentially as
- -- new units are loaded.
+ -- and this proved to be a significant source of inefficiency. We then
+ -- switched to using a table with a start point followed by a serial
+ -- search. Now we make sure source buffers are on a reasonable boundary
+ -- (see Types.Source_Align), and we can just use a direct look up in the
+ -- following table.
- -- The following table has an entry for each 4K range of possible
- -- Source_Ptr values. The value in the table is the lowest value
- -- Source_File_Index whose Source_Ptr range contains value in the
- -- range.
-
- -- For example, the entry with index 4 in this table represents Source_Ptr
- -- values in the range 4*4096 .. 5*4096-1. The Source_File_Index value
- -- stored would be the lowest numbered source file with at least one byte
- -- in this range.
-
- -- The algorithm used in Get_Source_File_Index is simply to access this
- -- table and then do a serial search starting at the given position. This
- -- will almost always terminate with one or two checks.
-
-- Note that this array is pretty large, but in most operating systems
-- it will not be allocated in physical memory unless it is actually used.
- Chunk_Power : constant := 12;
- Chunk_Size : constant := 2 ** Chunk_Power;
- -- Change comments above if value changed. Note that Chunk_Size must
- -- be a power of 2 (to allow for efficient access to the table).
-
Source_File_Index_Table :
- array (Int range 0 .. Int'Last / Chunk_Size) of Source_File_Index;
+ array (Int range 0 .. 1 + (Int'Last / Source_Align)) of Source_File_Index;
procedure Set_Source_File_Index_Table (Xnew : Source_File_Index);
-- Sets entries in the Source_File_Index_Table for the newly created
@@ -605,6 +586,7 @@
-- value is the physical line number in the source being compiled.
function Get_Source_File_Index (S : Source_Ptr) return Source_File_Index;
+ pragma Inline (Get_Source_File_Index);
-- Return file table index of file identified by given source pointer
-- value. This call must always succeed, since any valid source pointer
-- value belongs to some previously loaded source file.
Index: sinput-c.adb
===================================================================
--- sinput-c.adb (revision 203342)
+++ sinput-c.adb (working copy)
@@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
--- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2013, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
@@ -68,7 +68,8 @@
if X = Source_File.First then
Lo := First_Source_Ptr;
else
- Lo := Source_File.Table (X - 1).Source_Last + 1;
+ Lo := ((Source_File.Table (X - 1).Source_Last + Source_Align) /
+ Source_Align) * Source_Align;
end if;
Name_Len := Path'Length;
