[Ada] Implement machine parsable format for -gnatR output

This adds a new variant to the -gnatR switch, namely -gnatRj, which causes
the compiler to output representation information to a file in the JSON
data interchange format.  It can be combined with -gnatR0/1/2/3/m (but is
incompatible with -gnaRe and -gnatRs).

The information output in this mode is a superset of that output in the
traditional -gnatR mode, but is otherwise equivalent for the common part.

2018-05-29  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* doc/gnat_ugn/building_executable_programs_with_gnat.rst (Alphabetical
	List of All Switches): Document -gnatRj.
	(Debugging Control): Likewise.
	* gnat_ugn.texi: Regenerate.
	* opt.ads (List_Representation_Info_To_JSON): New boolean variable.
	* osint-c.adb (Create_Repinfo_File): Use the .json instead of .rep
	extension if List_Representation_Info_To_JSON is true.
	* repinfo.ads: Document the JSON output format.
	* repinfo.adb (List_Location): New procedure.
	(List_Array_Info): Add support for JSON output.
	(List_Entities): Likewise.
	(Unop): Likewise.
	(Binop): Likewise.
	(Print_Expr): Likewise.
	(List_Linker_Section): Likewise.
	(List_Mechanisms): Likewise.
	(List_Name): Likewise.
	(List_Object_Info): Likewise.
	(List_Record_Info): Likewise.
	(List_Component_Layout): Likewise.  Add Indent parameter.
	(List_Structural_Record_Layout): New procedure.
	(List_Attr): Add support for JSON output.
	(List_Type_Info): Likewise.
	(Write_Unknown_Val): Likewise.
	* switch-c.adb (Scan_Front_End_Switches) <R>: Deal with 'j'.
	* usage.adb (Usage): List -gnatRj.

From-SVN: r260868

gcc/ada/ChangeLog

 2018-05-29  Eric Botcazou  <ebotcazou@adacore.com>
 
+	* doc/gnat_ugn/building_executable_programs_with_gnat.rst (Alphabetical
+	List of All Switches): Document -gnatRj.
+	(Debugging Control): Likewise.
+	* gnat_ugn.texi: Regenerate.
+	* opt.ads (List_Representation_Info_To_JSON): New boolean variable.
+	* osint-c.adb (Create_Repinfo_File): Use the .json instead of .rep
+	extension if List_Representation_Info_To_JSON is true.
+	* repinfo.ads: Document the JSON output format.
+	* repinfo.adb (List_Location): New procedure.
+	(List_Array_Info): Add support for JSON output.
+	(List_Entities): Likewise.
+	(Unop): Likewise.
+	(Binop): Likewise.
+	(Print_Expr): Likewise.
+	(List_Linker_Section): Likewise.
+	(List_Mechanisms): Likewise.
+	(List_Name): Likewise.
+	(List_Object_Info): Likewise.
+	(List_Record_Info): Likewise.
+	(List_Component_Layout): Likewise.  Add Indent parameter.
+	(List_Structural_Record_Layout): New procedure.
+	(List_Attr): Add support for JSON output.
+	(List_Type_Info): Likewise.
+	(Write_Unknown_Val): Likewise.
+	* switch-c.adb (Scan_Front_End_Switches) <R>: Deal with 'j'.
+	* usage.adb (Usage): List -gnatRj.
+
+2018-05-29  Eric Botcazou  <ebotcazou@adacore.com>
+
 	* repinfo.adb (List_Component_Layout): New procedure extracted from...
 	(List_Record_Layout): ...here.  Invoke it.
 

gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst

@@ -2024,7 +2024,7 @@ Alphabetical List of All Switches
 
 .. index:: -gnatR  (gcc)
 
-:switch:`-gnatR[0/1/2/3][e][m][s]`
+:switch:`-gnatR[0|1|2|3][e][j][m][s]`
   Output representation information for declared types, objects and
   subprograms. Note that this switch is not allowed if a previous
   :switch:`-gnatD` switch has been given, since these two switches
@@ -5786,7 +5786,7 @@ Debugging Control
 
 .. index:: -gnatR  (gcc)
 
-:switch:`-gnatR[0|1|2|3][e][m][s]`
+:switch:`-gnatR[0|1|2|3][e][j][m][s]`
   This switch controls output from the compiler of a listing showing
   representation information for declared types, objects and subprograms.
   For :switch:`-gnatR0`, no information is output (equivalent to omitting
@@ -5817,6 +5817,13 @@ Debugging Control
   the output is to a file with the name :file:`file.rep` where file is
   the name of the corresponding source file.
 
+  If the switch is followed by a ``j`` (e.g., :switch:`-gnatR3j`), then
+  the output is to a file with the name :file:`file.json` where file is
+  the name of the corresponding source file, and it uses the JSON data
+  interchange format specified by the ECMA-404 standard. The semantic
+  description of this JSON output is available in the specification of
+  the Repinfo unit present in the compiler sources.
+
   Note that it is possible for record components to have zero size. In
   this case, the component clause uses an obvious extension of permitted
   Ada syntax, for example ``at 0 range 0 .. -1``.

gcc/ada/gnat_ugn.texi

@@ -9898,7 +9898,7 @@ Treat pragma Restrictions as Restriction_Warnings.
 
 @table @asis
 
-@item @code{-gnatR[0/1/2/3][e][m][s]}
+@item @code{-gnatR[0|1|2|3][e][j][m][s]}
 
 Output representation information for declared types, objects and
 subprograms. Note that this switch is not allowed if a previous
@@ -15013,7 +15013,7 @@ restriction warnings rather than restrictions.
 
 @table @asis
 
-@item @code{-gnatR[0|1|2|3][e][m][s]}
+@item @code{-gnatR[0|1|2|3][e][j][m][s]}
 
 This switch controls output from the compiler of a listing showing
 representation information for declared types, objects and subprograms.
@@ -15045,6 +15045,13 @@ If the switch is followed by an @code{s} (e.g., @code{-gnatR3s}), then
 the output is to a file with the name @code{file.rep} where file is
 the name of the corresponding source file.
 
+If the switch is followed by a @code{j} (e.g., @code{-gnatR3j}), then
+the output is to a file with the name @code{file.json} where file is
+the name of the corresponding source file, and it uses the JSON data
+interchange format specified by the ECMA-404 standard. The semantic
+description of this JSON output is available in the specification of
+the Repinfo unit present in the compiler sources.
+
 Note that it is possible for record components to have zero size. In
 this case, the component clause uses an obvious extension of permitted
 Ada syntax, for example @code{at 0 range 0 .. -1}.

gcc/ada/opt.ads

@@ -1003,6 +1003,12 @@ package Opt is
    --  of stdout. For example, if file x.adb is compiled using -gnatR2s then
    --  representation info is written to x.adb.ref.
 
+   List_Representation_Info_To_JSON : Boolean := False;
+   --  GNAT
+   --  Set true by -gnatRj switch. Causes information from -gnatR/1/2/3/m to be
+   --  written to file.json (where file is the name of the source file) in the
+   --  JSON data interchange format.
+
    List_Representation_Info_Mechanisms : Boolean := False;
    --  GNAT
    --  Set true by -gnatRm switch. Causes information on mechanisms to be

gcc/ada/osint-c.adb

@@ -273,8 +273,11 @@ package body Osint.C is
    begin
       Name_Buffer (1 .. Src'Length) := Src;
       Name_Len := Src'Length;
-      Discard := Create_Auxiliary_File (Name_Find, "rep");
-      return;
+      if List_Representation_Info_To_JSON then
+         Discard := Create_Auxiliary_File (Name_Find, "json");
+      else
+         Discard := Create_Auxiliary_File (Name_Find, "rep");
+      end if;
    end Create_Repinfo_File;
 
    ---------------------------

gcc/ada/repinfo.ads

@@ -141,48 +141,143 @@ package Repinfo is
    --  tree.def. Only a subset of these tree codes can actually appear.
    --  The names are the names from tree.def in Ada casing.
 
-   --  name                             code   description           operands
-
-   Cond_Expr        : constant TCode :=  1; -- conditional              3
-   Plus_Expr        : constant TCode :=  2; -- addition                 2
-   Minus_Expr       : constant TCode :=  3; -- subtraction              2
-   Mult_Expr        : constant TCode :=  4; -- multiplication           2
-   Trunc_Div_Expr   : constant TCode :=  5; -- truncating division      2
-   Ceil_Div_Expr    : constant TCode :=  6; -- division rounding up     2
-   Floor_Div_Expr   : constant TCode :=  7; -- division rounding down   2
-   Trunc_Mod_Expr   : constant TCode :=  8; -- mod for trunc_div        2
-   Ceil_Mod_Expr    : constant TCode :=  9; -- mod for ceil_div         2
-   Floor_Mod_Expr   : constant TCode := 10; -- mod for floor_div        2
-   Exact_Div_Expr   : constant TCode := 11; -- exact division           2
-   Negate_Expr      : constant TCode := 12; -- negation                 1
-   Min_Expr         : constant TCode := 13; -- minimum                  2
-   Max_Expr         : constant TCode := 14; -- maximum                  2
-   Abs_Expr         : constant TCode := 15; -- absolute value           1
-   Truth_And_Expr   : constant TCode := 16; -- boolean and              2
-   Truth_Or_Expr    : constant TCode := 17; -- boolean or               2
-   Truth_Xor_Expr   : constant TCode := 18; -- boolean xor              2
-   Truth_Not_Expr   : constant TCode := 19; -- boolean not              1
-   Lt_Expr          : constant TCode := 20; -- comparison <             2
-   Le_Expr          : constant TCode := 21; -- comparison <=            2
-   Gt_Expr          : constant TCode := 22; -- comparison >             2
-   Ge_Expr          : constant TCode := 23; -- comparison >=            2
-   Eq_Expr          : constant TCode := 24; -- comparison =             2
-   Ne_Expr          : constant TCode := 25; -- comparison /=            2
-   Bit_And_Expr     : constant TCode := 26; -- bitwise and              2
+   --  name                             code   description     operands  symbol
+
+   Cond_Expr        : constant TCode :=  1; -- conditional          3      ?<>
+   Plus_Expr        : constant TCode :=  2; -- addition             2        +
+   Minus_Expr       : constant TCode :=  3; -- subtraction          2        -
+   Mult_Expr        : constant TCode :=  4; -- multiplication       2        *
+   Trunc_Div_Expr   : constant TCode :=  5; -- truncating div       2       /t
+   Ceil_Div_Expr    : constant TCode :=  6; -- div rounding up      2       /c
+   Floor_Div_Expr   : constant TCode :=  7; -- div rounding down    2       /f
+   Trunc_Mod_Expr   : constant TCode :=  8; -- mod for trunc_div    2     modt
+   Ceil_Mod_Expr    : constant TCode :=  9; -- mod for ceil_div     2     modc
+   Floor_Mod_Expr   : constant TCode := 10; -- mod for floor_div    2     modf
+   Exact_Div_Expr   : constant TCode := 11; -- exact div            2       /e
+   Negate_Expr      : constant TCode := 12; -- negation             1        -
+   Min_Expr         : constant TCode := 13; -- minimum              2      min
+   Max_Expr         : constant TCode := 14; -- maximum              2      max
+   Abs_Expr         : constant TCode := 15; -- absolute value       1      abs
+   Truth_And_Expr   : constant TCode := 16; -- boolean and          2      and
+   Truth_Or_Expr    : constant TCode := 17; -- boolean or           2       or
+   Truth_Xor_Expr   : constant TCode := 18; -- boolean xor          2      xor
+   Truth_Not_Expr   : constant TCode := 19; -- boolean not          1      not
+   Lt_Expr          : constant TCode := 20; -- comparison <         2        <
+   Le_Expr          : constant TCode := 21; -- comparison <=        2       <=
+   Gt_Expr          : constant TCode := 22; -- comparison >         2        >
+   Ge_Expr          : constant TCode := 23; -- comparison >=        2       >=
+   Eq_Expr          : constant TCode := 24; -- comparison =         2       ==
+   Ne_Expr          : constant TCode := 25; -- comparison /=        2       !=
+   Bit_And_Expr     : constant TCode := 26; -- bitwise and          2        &
 
    --  The following entry is used to represent a discriminant value in
    --  the tree. It has a special tree code that does not correspond
    --  directly to a GCC node. The single operand is the index number
    --  of the discriminant in the record (1 = first discriminant).
 
-   Discrim_Val      : constant TCode :=  0;  -- discriminant value      1
+   Discrim_Val      : constant TCode :=  0;  -- discriminant value  1        #
 
    --  The following entry is used to represent a value not known at
    --  compile time in the tree, other than a discriminant value. It
    --  has a special tree code that does not correspond directly to
    --  a GCC node. The single operand is an arbitrary index number.
 
-   Dynamic_Val      : constant TCode := 27;  -- dynamic value           1
+   Dynamic_Val      : constant TCode := 27;  -- dynamic value       1      var
+
+   ----------------------------
+   -- The JSON output format --
+   ----------------------------
+
+   --  The representation information can be output to a file in the JSON
+   --  data interchange format specified by the ECMA-404 standard. In the
+   --  following description, the terminology is that of the JSON syntax
+   --  from the ECMA document and of the JSON grammar from www.json.org.
+
+   --  The output is a concatenation of entities
+
+   --  An entity is an object whose members are pairs taken from:
+
+   --    "name"                 :  string
+   --    "location"             :  string
+   --    "record"               :  array of components
+   --    "variant"              :  array of variants
+   --    "formal"               :  array of formal parameters
+   --    "mechanism"            :  string
+   --    "Size"                 :  numerical expression
+   --    "Object_Size"          :  numerical expression
+   --    "Value_Size"           :  numerical expression
+   --    "Component_Size"       :  numerical expression
+   --    "Range"                :  array of numbers
+   --    "Small"                :  number
+   --    "Alignment"            :  number
+   --    "Convention"           :  string
+   --    "Linker_Section"       :  string
+   --    "Bit_Order"            :  string
+   --    "Scalar_Storage_Order" :  string
+
+   --    "name" and "location" are present for every entity and come from the
+   --    declaration of the associated Ada entity. The value of "name" is the
+   --    fully qualified Ada name. The value of "location" is the expanded
+   --    chain of instantiation locations that contains the entity.
+   --    "record" is present for every record type and its value is the list of
+   --    components. "variant" is present only if the record type has a variant
+   --    part and its value is the list of variants.
+   --    "formal" is present for every subprogram and entry, and its value is
+   --    the list of formal parameters. "mechanism" is present for functions
+   --    only and its value is the return mechanim.
+   --    The other pairs may be present when the eponymous aspect/attribute is
+   --    defined for the Ada entity, and their value is set by the language.
+
+   --  A component is an object whose members are pairs taken from:
+
+   --    "name"                 :  string
+   --    "Position"             :  numerical expression
+   --    "First_Bit"            :  number
+   --    "Size"                 :  numerical expression
+
+   --    The four pairs are present for every component. "name" comes from the
+   --    declaration of the component in the record type and its value is the
+   --    unqualified Ada name. The other three pairs come from the layout of
+   --    the type and their value is that of the eponymous attribute set by
+   --    the language.
+
+   --  A variant is an object whose members are pairs taken from:
+
+   --    "present"              :  numerical expression
+   --    "record"               :  array of components
+   --    "variant"              :  array of variants
+
+   --    "present" and "record" are present for every variant. The value of
+   --    "present" is a boolean expression that evaluates to true when the
+   --    components of the variant are contained in the record type and to
+   --    false when they are not. The value of "record" is the list of
+   --    components in the variant. "variant" is present only if the variant
+   --    itself has a variant part and its value is the list of (sub)variants.
+
+   --  A formal parameter is an object whose members are pairs taken from:
+
+   --    "name"                 :  string
+   --    "mechanism"            :  string
+
+   --    The two pairs are present for every formal parameter. "name" comes
+   --    from the declaration of the parameter in the subprogram or entry
+   --    and its value is the unqualified Ada name. The value of "mechanism"
+   --    is the passing mechanism for the parameter set by the language.
+
+   --  A numerical expression is either a number or an object whose members
+   --  are pairs taken from:
+
+   --    "code"                 :  string
+   --    "operands"             :  array of numerical expressions
+
+   --    The two pairs are present for every such object. The value of "code"
+   --    is a symbol taken from the table defining the TCode type above. The
+   --    number of elements of the value of "operands" is specified by the
+   --    operands column in the line associated with the symbol in the table.
+
+   --    As documented above, the full back annotation is only done in -gnatR3
+   --    or ASIS mode. In the other cases, if the numerical expression is not
+   --    a number, then it is replaced with the "??" string.
 
    ------------------------
    -- The gigi Interface --

gcc/ada/switch-c.adb

@@ -1211,6 +1211,9 @@ package body Switch.C is
                   when 's' =>
                      List_Representation_Info_To_File := True;
 
+                  when 'j' =>
+                     List_Representation_Info_To_JSON := True;
+
                   when 'm' =>
                      List_Representation_Info_Mechanisms := True;
 
@@ -1224,6 +1227,14 @@ package body Switch.C is
                   Ptr := Ptr + 1;
                end loop;
 
+               if List_Representation_Info_To_JSON then
+                  if List_Representation_Info_To_File then
+                     Osint.Fail ("-gnatRs is incompatible with -gnatRj");
+                  elsif List_Representation_Info_Extended then
+                     Osint.Fail ("-gnatRe is incompatible with -gnatRj");
+                  end if;
+               end if;
+
             --  -gnats (syntax check only)
 
             when 's' =>

gcc/ada/usage.adb

@@ -405,6 +405,8 @@ begin
      ("List rep info (?=0/1/2/3/e/m for none/types/all/symbolic/ext/mech)");
    Write_Switch_Char ("R?s");
    Write_Line ("List rep info to file.rep instead of standard output");
+   Write_Switch_Char ("R?j");
+   Write_Line ("List rep info to file.json instead of standard output");
 
    --  Line for -gnats switch