2007-04-20 Javier Miranda <miranda@adacore.com>

	    Nicolas Setton  <setton@adacore.com>

	* exp_dbug.adb (Get_Encoded_Name): Modified to continue providing its
	functionality when the backend is generating code.
	Otherwise any serious error
	reported by the backend calling the frontend routine Error_Msg
	changes the Compilation_Mode to Check_Semantics, disables the
	functionality of this routine and causes the generation of
	spureous additional errors.

	* exp_dbug.ads (Pointers to Unconstrained Arrays): Document the
	debugging information now generated by the compiler for fat-pointer
	types.
	Document the contents of DW_AT_producer in the GNAT Vendor extensions to
	DWARF2/3.
	Document GNAT Vendor extensions to DWARF 2/3 and the "-gdwarf+" switch.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@125402 138bc75d-0d04-0410-961f-82ee72b054a4

2 files changed, 73 insertions, 17 deletions

diff --git a/gcc/ada/exp_dbug.adb b/gcc/ada/exp_dbug.adb
index babdef20daf..367ed2d6775 100644
--- a/gcc/ada/exp_dbug.adb
+++ b/gcc/ada/exp_dbug.adb
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1996-2006, Free Software Foundation, Inc.         --
+--          Copyright (C) 1996-2007, 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- --
@@ -28,7 +28,6 @@ with Alloc;    use Alloc;
 with Atree;    use Atree;
 with Debug;    use Debug;
 with Einfo;    use Einfo;
-with Namet;    use Namet;
 with Nlists;   use Nlists;
 with Nmake;    use Nmake;
 with Opt;      use Opt;
@@ -492,12 +491,22 @@ package body Exp_Dbug is
       Has_Suffix : Boolean;
 
    begin
-      --  If not generating code, there is no need to create encoded
-      --  names, and problems when the back-end is called to annotate
-      --  types without full code generation. See comments at beginning
-      --  of Get_External_Name_With_Suffix for additional details.
+      --  If not generating code, there is no need to create encoded names, and
+      --  problems when the back-end is called to annotate types without full
+      --  code generation. See comments in Get_External_Name_With_Suffix for
+      --  additional details.
 
-      if Operating_Mode /= Generate_Code then
+      --  However we do create encoded names if the back end is active, even
+      --  if Operating_Mode got reset. Otherwise any serious error reported
+      --  by the backend calling Error_Msg changes the Compilation_Mode to
+      --  Check_Semantics, which disables the functionality of this routine,
+      --  causing the generation of spurious additional errors.
+
+      --  Couldn't we just test Original_Operating_Mode here? ???
+
+      if Operating_Mode /= Generate_Code
+        and then not Generating_Code
+      then
          return;
       end if;
 
diff --git a/gcc/ada/exp_dbug.ads b/gcc/ada/exp_dbug.ads
index 49979e30b8d..3e3e992707a 100644
--- a/gcc/ada/exp_dbug.ads
+++ b/gcc/ada/exp_dbug.ads
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 S p e c                                  --
 --                                                                          --
---          Copyright (C) 1996-2006, Free Software Foundation, Inc.         --
+--          Copyright (C) 1996-2007, 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- --
@@ -28,6 +28,7 @@
 --  debugger. In accordance with the Dwarf 2.2 specification, certain
 --  type names are encoded to provide information to the debugger.
 
+with Namet; use Namet;
 with Types; use Types;
 with Uintp; use Uintp;
 
@@ -44,11 +45,11 @@ package Exp_Dbug is
    --  are the enclosing scopes (not including Standard at the start).
 
    --  The encoding of the name follows this basic qualified naming scheme,
-   --  where the encoding of individual entity names is as described in
-   --  Namet (i.e. in particular names present in the original source are
-   --  folded to all lower case, with upper half and wide characters encoded
-   --  as described in Namet). Upper case letters are used only for entities
-   --  generated by the compiler.
+   --  where the encoding of individual entity names is as described in Namet
+   --  (i.e. in particular names present in the original source are folded to
+   --  all lower case, with upper half and wide characters encoded as described
+   --  in Namet). Upper case letters are used only for entities generated by
+   --  the compiler.
 
    --  There are two cases, global entities, and local entities. In more formal
    --  terms, local entities are those which have a dynamic enclosing scope,
@@ -1247,10 +1248,19 @@ package Exp_Dbug is
    --        The bounds may be any integral type. In the case of an enumeration
    --        type, Enum_Rep values are used.
 
-   --      The debugging information will sometimes reference an anonymous fat
-   --      pointer type. Such types are given the name xxx___XUP, where xxx is
-   --      the name of the designated type. If the debugger is asked to output
-   --      such a type name, the appropriate form is "access xxx".
+   --      For a given unconstrained array type, the compiler will generate one
+   --      fat-pointer type whose name is "arr___XUP", where "arr" is the name
+   --      of the array type, and use it to represent the array type itself in
+   --      the debugging information.
+   --      For each pointer to this unconstrained array type, the compiler will
+   --      generate a typedef that points to the above "arr___XUP" fat-pointer
+   --      type. As a consequence, when it comes to fat-pointer types:
+
+   --        1. The type name is given by the typedef
+
+   --        2. If the debugger is asked to output the type, the appropriate
+   --           form is "access arr", except if the type name is "arr___XUP"
+   --           for which it is the array definition.
 
    --    Thin Pointers
 
@@ -1501,4 +1511,41 @@ package Exp_Dbug is
    --  are missing and deal as best as it can with the limited information
    --  available.
 
+   ---------------------------------
+   -- GNAT Extensions to DWARF2/3 --
+   ---------------------------------
+
+   --  If the compiler switch "-gdwarf+" is specified, GNAT Vendor extensions
+   --  to DWARF2/3 are generated, with the following variations from the above
+   --  specification.
+
+   --   Change in the contents of the DW_AT_name attribute.
+   --    The operators are represented in their natural form. (Ie, the addition
+   --    operator is written as "+" instead of "Oadd").
+   --    The component separation string is "." instead of "__"
+
+   --   Introduction of DW_AT_GNAT_encoding, encoded with value 0x2301.
+   --    Any debugging information entry representing a program entity, named
+   --    or implicit, may have a DW_AT_GNAT_encoding attribute. The value of
+   --    this attribute is a string representing the suffix internally added
+   --    by GNAT for various purposes, mainly for representing debug
+   --    information compatible with other formats.
+
+   --    If a debugging information entry has multiple encodings, all of them
+   --    will be listed in DW_AT_GNAT_encoding. The separator for this list
+   --    is ':'.
+
+   --   Introduction of DW_AT_GNAT_descriptive_type, encoded with value 0x2302
+   --    Any debugging information entry representing a type may have a
+   --    DW_AT_GNAT_descriptive_type attribute whose value is a reference,
+   --    pointing to a debugging information entry representing another type
+   --    associated to the type.
+
+   --   Modification of the contents of the DW_AT_producer string.
+   --    When emitting full GNAT Vendor extensions to DWARF2/3, "-gdwarf+"
+   --    is appended to the DW_AT_producer string.
+   --
+   --    When emitting only DW_AT_GNAT_descriptive_type, "-gdwarf+-" is
+   --    appended to the DW_AT_producer string.
+
 end Exp_Dbug;