ada: Adjust runtime library and User's Guide to PIE default on Linux

gcc/ada/

	* libgnat/g-traceb.ads: Minor tweaks in the commentary.
	(Executable_Load_Address): New function.
	* doc/gnat_ugn/gnat_and_program_execution.rst (Non-Symbolic
	Traceback): Adjust to PIE default on Linux.
	(Symbolic Traceback): Likewise.
	* doc/gnat_ugn/gnat_utility_programs.rst (gnatsymbolize): Likewise.
	* gnat_ugn.texi: Regenerate.

2 files changed, 45 insertions, 31 deletions

diff --git a/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst b/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst
index c239c36..45ecea7 100644
--- a/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst
+++ b/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst
@@ -859,16 +859,18 @@ bug occurs, and then be able to retrieve the sequence of calls with the same
 program compiled with debug information.
 
 However the ``addr2line`` tool does not work with Position-Independent Code
-(PIC), the historical example being Windows DLLs, which nowadays encompasses
-Position-Independent Executables (PIE) on recent Windows versions.
-
-In order to translate addresses into the source lines with Position-Independent
-Executables on recent Windows versions, in other words without using the switch
-:switch:`-no-pie` during linking, you need to use the ``gnatsymbolize`` tool
-with :switch:`--load` instead of the ``addr2line`` tool. The main difference
-is that you need to copy the Load Address output in the traceback ahead of the
-sequence of addresses. And the default mode of ``gnatsymbolize`` is equivalent
-to that of ``addr2line`` with the above switches, so none of them is needed::
+(PIC), the historical example being Linux dynamic libraries and Windows DLLs,
+which nowadays encompasse Position-Independent Executables (PIE) on recent
+Linux and Windows versions.
+
+In order to translate addresses the source lines with Position-Independent
+Executables on recent Linux and Windows versions, in other words without
+using the switch :switch:`-no-pie` during linking, you need to use the
+``gnatsymbolize`` tool with :switch:`--load` instead of the ``addr2line``
+tool. The main difference is that you need to copy the Load Address output
+in the traceback ahead of the sequence of addresses. And the default mode
+of ``gnatsymbolize`` is equivalent to that of ``addr2line`` with the above
+switches, so none of them is needed::
 
      $ gnatmake stb -g -bargs -E
      $ stb
@@ -879,7 +881,7 @@ to that of ``addr2line`` with the above switches, so none of them is needed::
      Call stack traceback locations:
      0x401373 0x40138b 0x40139c 0x401335 0x4011c4 0x4011f1 0x77e892a4
 
-     $ gnatsymbolize --load stb 0x400000 0x401373 0x40138b 0x40139c 0x401335
+     $ gnatsymbolize --load stb 0x400000 0x401373 0x40138b 0x40139c 0x401335 \
         0x4011c4 0x4011f1 0x77e892a4
 
      0x00401373 Stb.P1 at stb.adb:5
@@ -957,12 +959,17 @@ addresses to strings:
       with Ada.Text_IO;
       with GNAT.Traceback;
       with GNAT.Debug_Utilities;
+      with System;
 
       procedure STB is
 
          use Ada;
+         use Ada.Text_IO;
          use GNAT;
          use GNAT.Traceback;
+         use System;
+
+         LA : constant Address := Executable_Load_Address;
 
          procedure P1 is
             TB  : Tracebacks_Array (1 .. 10);
@@ -972,14 +979,14 @@ addresses to strings:
          begin
             Call_Chain (TB, Len);
 
-            Text_IO.Put ("In STB.P1 : ");
+            Put ("In STB.P1 : ");
 
             for K in 1 .. Len loop
-               Text_IO.Put (Debug_Utilities.Image (TB (K)));
-               Text_IO.Put (' ');
+               Put (Debug_Utilities.Image_C (TB (K)));
+               Put (' ');
             end loop;
 
-            Text_IO.New_Line;
+            New_Line;
          end P1;
 
          procedure P2 is
@@ -988,6 +995,10 @@ addresses to strings:
          end P2;
 
       begin
+         if LA /= Null_Address then
+            Put_Line ("Load address: " & Debug_Utilities.Image_C (LA));
+         end if;
+
          P2;
       end STB;
 
@@ -996,8 +1007,9 @@ addresses to strings:
      $ gnatmake stb -g
      $ stb
 
-     In STB.P1 : 16#0040_F1E4# 16#0040_14F2# 16#0040_170B# 16#0040_171C#
-     16#0040_1461# 16#0040_11C4# 16#0040_11F1# 16#77E8_92A4#
+     Load address: 0x400000
+     In STB.P1 : 0x40F1E4 0x4014F2 0x40170B 0x40171C 0x401461 0x4011C4 \
+       0x4011F1 0x77E892A4
 
 
 You can then get further information by invoking the ``addr2line`` tool or
diff --git a/gcc/ada/doc/gnat_ugn/gnat_utility_programs.rst b/gcc/ada/doc/gnat_ugn/gnat_utility_programs.rst
index 17d3e0d..f2d42e9 100644
--- a/gcc/ada/doc/gnat_ugn/gnat_utility_programs.rst
+++ b/gcc/ada/doc/gnat_ugn/gnat_utility_programs.rst
@@ -2187,30 +2187,32 @@ building specialized scripts.
 
   This program, when built and run, prints a list of addresses which
   correspond to the traceback when inside function ``Call_Me_Third``.
-  For instance, on x86_64 GNU/Linux:
+  For instance, on x86-64 GNU/Linux:
 
     ::
 
        $ gnatmake -g -q foo.adb
        $ ./foo
-       0x0000000000402561
-       0x00000000004025EF
-       0x00000000004025FB
-       0x0000000000402611
-       0x00000000004024C7
+       Load address: 0x00005586C9D7D000
+       0x00005586C9D81105
+       0x00005586C9D8119B
+       0x00005586C9D811A7
+       0x00005586C9D8128C
+       0x00005586C9D81069
 
   ``gnatsymbolize`` can be used to translate those addresses into
   code locations as follow:
 
     ::
 
-       $ gnatsymbolize foo 0x0000000000402561 0x00000000004025EF \
-           0x00000000004025FB 0x0000000000402611 0x00000000004024C7
-       Pck.Call_Me_Third at pck.adb:12
-       Pck.Call_Me_Second at pck.adb:20
-       Pck.Call_Me_First at pck.adb:25
-       Foo at foo.adb:6
-       Main at b~foo.adb:184
+       $ gnatsymbolize --load foo 0x00005586C9D7D000 0x00005586C9D81105 \
+           0x00005586C9D8119B 0x00005586C9D811A7 0x00005586C9D8128C \
+           0x00005586C9D81069
+       0x5586c9d81105 Pck.Call_Me_Third at pck.adb:12
+       0x5586c9d8119b Pck.Call_Me_Second at pck.adb:20
+       0x5586c9d811a7 Pck.Call_Me_First at pck.adb:25
+       0x5586c9d8128c Foo at foo.adb:6
+       0x5586c9d81069 Main at b~foo.adb:199
 
   Switches for ``gnatsymbolize``
   ------------------------------
@@ -2243,7 +2245,7 @@ building specialized scripts.
 
   :switch:`--load`
     Interpret the first address as the load address of the executable.
-    This is needed for position-independent executables on Windows.
+    This is needed for position-independent executables on Linux and Windows.
 
   Requirements for Correct Operation
   ----------------------------------