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------------------------------------------------------------------------------

--                                                                          --

--                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --

--                                                                          --

--                   S Y S T E M - S T A C K _ U S A G E                    --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--         Copyright (C) 2004-2009, Free Software Foundation, Inc.          --

--                                                                          --

-- GNARL 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- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNARL was developed by the GNARL team at Florida State University.       --

-- Extensive contributions were provided by Ada Core Technologies, Inc.     --

--                                                                          --

------------------------------------------------------------------------------

with System.Parameters;

with System.CRTL;

with System.IO;

package body System.Stack_Usage is

   use System.Storage_Elements;

   use System;

   use System.IO;

   use Interfaces;

   -----------------

   -- Stack_Slots --

   -----------------

   --  Stackl_Slots is an internal data type to represent a sequence of real

   --  stack slots initialized with a provided pattern, with operations to

   --  abstract away the target call stack growth direction.

   type Stack_Slots is array (Integer range <>) of Pattern_Type;

   for Stack_Slots'Component_Size use Pattern_Type'Object_Size;

   --  We will carefully handle the initializations ourselves and might want

   --  to remap an initialized overlay later on with an address clause.

   pragma Suppress_Initialization (Stack_Slots);

   --  The abstract Stack_Slots operations all operate over the simple array

   --  memory model:

   --  memory addresses increasing ---->

   --  Slots('First)                                           Slots('Last)

   --    |                                                             |

   --    V                                                             V

   --  +------------------------------------------------------------------+

   --  |####|                                                        |####|

   --  +------------------------------------------------------------------+

   --  What we call Top or Bottom always denotes call chain leaves or entry

   --  points respectively, and their relative positions in the stack array

   --  depends on the target stack growth direction:

   --                           Stack_Grows_Down

   --                <----- calls push frames towards decreasing addresses

   --   Top(most) Slot                                   Bottom(most) Slot

   --    |                                                            |

   --    V                                                            V

   --  +------------------------------------------------------------------+

   --  |####|                            | leaf frame | ... | entry frame |

   --  +------------------------------------------------------------------+

   --                           Stack_Grows_Up

   --   calls push frames towards increasing addresses ----->

   --   Bottom(most) Slot                                    Top(most) Slot

   --    |                                                             |

   --    V                                                             V

   --  +------------------------------------------------------------------+

   --  | entry frame | ... | leaf frame |                            |####|

   --  +------------------------------------------------------------------+

   function Top_Slot_Index_In (Stack : Stack_Slots) return Integer;

   --  Index of the stack Top slot in the Slots array, denoting the latest

   --  possible slot available to call chain leaves.

   function Bottom_Slot_Index_In (Stack : Stack_Slots) return Integer;

   --  Index of the stack Bottom slot in the Slots array, denoting the first

   --  possible slot available to call chain entry points.

   function Push_Index_Step_For (Stack : Stack_Slots) return Integer;

   --  By how much do we need to update a Slots index to Push a single slot on

   --  the stack.

   function Pop_Index_Step_For (Stack : Stack_Slots) return Integer;

   --  By how much do we need to update a Slots index to Pop a single slot off

   --  the stack.

   pragma Inline_Always (Top_Slot_Index_In);

   pragma Inline_Always (Bottom_Slot_Index_In);

   pragma Inline_Always (Push_Index_Step_For);

   pragma Inline_Always (Pop_Index_Step_For);

   -----------------------

   -- Top_Slot_Index_In --

   -----------------------

   function Top_Slot_Index_In (Stack : Stack_Slots) return Integer is

   begin

      if System.Parameters.Stack_Grows_Down then

         return Stack'First;

      else

         return Stack'Last;

      end if;

   end Top_Slot_Index_In;

   ----------------------------

   --  Bottom_Slot_Index_In  --

   ----------------------------

   function Bottom_Slot_Index_In (Stack : Stack_Slots) return Integer is

   begin

      if System.Parameters.Stack_Grows_Down then

         return Stack'Last;

      else

         return Stack'First;

      end if;

   end Bottom_Slot_Index_In;

   -------------------------

   -- Push_Index_Step_For --

   -------------------------

   function Push_Index_Step_For (Stack : Stack_Slots) return Integer is

      pragma Unreferenced (Stack);

   begin

      if System.Parameters.Stack_Grows_Down then

         return -1;

      else

         return +1;

      end if;

   end Push_Index_Step_For;

   ------------------------

   -- Pop_Index_Step_For --

   ------------------------

   function Pop_Index_Step_For (Stack : Stack_Slots) return Integer is

   begin

      return -Push_Index_Step_For (Stack);

   end Pop_Index_Step_For;

   -------------------

   -- Unit Services --

   -------------------

   --  Now the implementation of the services offered by this unit, on top of

   --  the Stack_Slots abstraction above.

   Index_Str       : constant String  := "Index";

   Task_Name_Str   : constant String  := "Task Name";

   Stack_Size_Str  : constant String  := "Stack Size";

   Actual_Size_Str : constant String  := "Stack usage";

   function Get_Usage_Range (Result : Task_Result) return String;

   --  Return string representing the range of possible result of stack usage

   procedure Output_Result

     (Result_Id          : Natural;

      Result             : Task_Result;

      Max_Stack_Size_Len : Natural;

      Max_Actual_Use_Len : Natural);

   --  Prints the result on the standard output. Result Id is the number of

   --  the result in the array, and Result the contents of the actual result.

   --  Max_Stack_Size_Len and Max_Actual_Use_Len are used for displaying the

   --  proper layout. They hold the maximum length of the string representing

   --  the Stack_Size and Actual_Use values.

   ----------------

   -- Initialize --

   ----------------

   procedure Initialize (Buffer_Size : Natural) is

      Bottom_Of_Stack  : aliased Integer;

      Stack_Size_Chars : System.Address;

   begin

      --  Initialize the buffered result array

      Result_Array := new Result_Array_Type (1 .. Buffer_Size);

      Result_Array.all :=

        (others =>

           (Task_Name => (others => ASCII.NUL),

            Variation => 0,

            Value     => 0,

            Max_Size  => 0));

      --  Set the Is_Enabled flag to true, so that the task wrapper knows that

      --  it has to handle dynamic stack analysis

      Is_Enabled := True;

      Stack_Size_Chars := System.CRTL.getenv ("GNAT_STACK_LIMIT" & ASCII.NUL);

      --  If variable GNAT_STACK_LIMIT is set, then we will take care of the

      --  environment task, using GNAT_STASK_LIMIT as the size of the stack.

      --  It doesn't make sens to process the stack when no bound is set (e.g.

      --  limit is typically up to 4 GB).

      if Stack_Size_Chars /= Null_Address then

         declare

            My_Stack_Size : Integer;

         begin

            My_Stack_Size := System.CRTL.atoi (Stack_Size_Chars) * 1024;

            Initialize_Analyzer

              (Environment_Task_Analyzer,

               "ENVIRONMENT TASK",

               My_Stack_Size,

               My_Stack_Size,

               System.Storage_Elements.To_Integer (Bottom_Of_Stack'Address));

            Fill_Stack (Environment_Task_Analyzer);

            Compute_Environment_Task := True;

         end;

      --  GNAT_STACK_LIMIT not set

      else

         Compute_Environment_Task := False;

      end if;

   end Initialize;

   ----------------

   -- Fill_Stack --

   ----------------

   procedure Fill_Stack (Analyzer : in out Stack_Analyzer) is

      --  Change the local variables and parameters of this function with

      --  super-extra care. The more the stack frame size of this function is

      --  big, the more an "instrumentation threshold at writing" error is

      --  likely to happen.

      Stack_Used_When_Filling : Integer;

      Current_Stack_Level     : aliased Integer;

   begin

      --  Readjust the pattern size. When we arrive in this function, there is

      --  already a given amount of stack used, that we won't analyze.

      Stack_Used_When_Filling :=

        Stack_Size

         (Analyzer.Bottom_Of_Stack,

          To_Stack_Address (Current_Stack_Level'Address))

          + Natural (Current_Stack_Level'Size);

      if Stack_Used_When_Filling > Analyzer.Pattern_Size then

         --  In this case, the known size of the stack is too small, we've

         --  already taken more than expected, so there's no possible

         --  computation

         Analyzer.Pattern_Size := 0;

      else

         Analyzer.Pattern_Size :=

           Analyzer.Pattern_Size - Stack_Used_When_Filling;

      end if;

      declare

         Stack : aliased Stack_Slots

                           (1 .. Analyzer.Pattern_Size / Bytes_Per_Pattern);

      begin

         Stack := (others => Analyzer.Pattern);

         Analyzer.Stack_Overlay_Address := Stack'Address;

         if Analyzer.Pattern_Size /= 0 then

            Analyzer.Bottom_Pattern_Mark :=

              To_Stack_Address (Stack (Bottom_Slot_Index_In (Stack))'Address);

            Analyzer.Top_Pattern_Mark :=

              To_Stack_Address (Stack (Top_Slot_Index_In (Stack))'Address);

         else

            Analyzer.Bottom_Pattern_Mark := To_Stack_Address (Stack'Address);

            Analyzer.Top_Pattern_Mark := To_Stack_Address (Stack'Address);

         end if;

         --  If Arr has been packed, the following assertion must be true (we

         --  add the size of the element whose address is:

         --    Min (Analyzer.Inner_Pattern_Mark, Analyzer.Outer_Pattern_Mark)):

         pragma Assert

           (Analyzer.Pattern_Size = 0 or else

            Analyzer.Pattern_Size =

              Stack_Size

                (Analyzer.Top_Pattern_Mark, Analyzer.Bottom_Pattern_Mark));

      end;

   end Fill_Stack;

   -------------------------

   -- Initialize_Analyzer --

   -------------------------

   procedure Initialize_Analyzer

     (Analyzer         : in out Stack_Analyzer;

      Task_Name        : String;

      My_Stack_Size    : Natural;

      Max_Pattern_Size : Natural;

      Bottom           : Stack_Address;

      Pattern          : Unsigned_32 := 16#DEAD_BEEF#)

   is

   begin

      --  Initialize the analyzer fields

      Analyzer.Bottom_Of_Stack := Bottom;

      Analyzer.Stack_Size      := My_Stack_Size;

      Analyzer.Pattern_Size    := Max_Pattern_Size;

      Analyzer.Pattern         := Pattern;

      Analyzer.Result_Id       := Next_Id;

      Analyzer.Task_Name       := (others => ' ');

      --  Compute the task name, and truncate if bigger than Task_Name_Length

      if Task_Name'Length <= Task_Name_Length then

         Analyzer.Task_Name (1 .. Task_Name'Length) := Task_Name;

      else

         Analyzer.Task_Name :=

           Task_Name (Task_Name'First ..

                        Task_Name'First + Task_Name_Length - 1);

      end if;

      Next_Id := Next_Id + 1;

   end Initialize_Analyzer;

   ----------------

   -- Stack_Size --

   ----------------

   function Stack_Size

     (SP_Low  : Stack_Address;

      SP_High : Stack_Address) return Natural

   is

   begin

      if SP_Low > SP_High then

         return Natural (SP_Low - SP_High + 4);

      else

         return Natural (SP_High - SP_Low + 4);

      end if;

   end Stack_Size;

   --------------------

   -- Compute_Result --

   --------------------

   procedure Compute_Result (Analyzer : in out Stack_Analyzer) is

      --  Change the local variables and parameters of this function with

      --  super-extra care. The larger the stack frame size of this function

      --  is, the more an "instrumentation threshold at reading" error is

      --  likely to happen.

      Stack : Stack_Slots (1 .. Analyzer.Pattern_Size / Bytes_Per_Pattern);

      for Stack'Address use Analyzer.Stack_Overlay_Address;

   begin

      Analyzer.Topmost_Touched_Mark := Analyzer.Bottom_Pattern_Mark;

      if Analyzer.Pattern_Size = 0 then

         return;

      end if;

      --  Look backward from the topmost possible end of the marked stack to

      --  the bottom of it. The first index not equals to the patterns marks

      --  the beginning of the used stack.

      declare

         Top_Index    : constant Integer := Top_Slot_Index_In (Stack);

         Bottom_Index : constant Integer := Bottom_Slot_Index_In (Stack);

         Step         : constant Integer := Pop_Index_Step_For (Stack);

         J            : Integer;

      begin

         J := Top_Index;

         loop

            if Stack (J) /= Analyzer.Pattern then

               Analyzer.Topmost_Touched_Mark

                 := To_Stack_Address (Stack (J)'Address);

               exit;

            end if;

            exit when J = Bottom_Index;

            J := J + Step;

         end loop;

      end;

   end Compute_Result;

   ---------------------

   -- Get_Usage_Range --

   ---------------------

   function Get_Usage_Range (Result : Task_Result) return String is

      Variation_Used_Str : constant String :=

                             Natural'Image (Result.Variation);

      Value_Used_Str     : constant String :=

                             Natural'Image (Result.Value);

   begin

      return Value_Used_Str & " +/- " & Variation_Used_Str;

   end Get_Usage_Range;

   ---------------------

   --  Output_Result --

   ---------------------

   procedure Output_Result

     (Result_Id          : Natural;

      Result             : Task_Result;

      Max_Stack_Size_Len : Natural;

      Max_Actual_Use_Len : Natural)

   is

      Result_Id_Str     : constant String := Natural'Image (Result_Id);

      My_Stack_Size_Str : constant String := Natural'Image (Result.Max_Size);

      Actual_Use_Str    : constant String := Get_Usage_Range (Result);

      Result_Id_Blanks  : constant

        String (1 .. Index_Str'Length - Result_Id_Str'Length)    :=

          (others => ' ');

      Stack_Size_Blanks : constant

        String (1 .. Max_Stack_Size_Len - My_Stack_Size_Str'Length) :=

          (others => ' ');

      Actual_Use_Blanks : constant

        String (1 .. Max_Actual_Use_Len - Actual_Use_Str'Length) :=

          (others => ' ');

   begin

      Set_Output (Standard_Error);

      Put (Result_Id_Blanks & Natural'Image (Result_Id));

      Put (" | ");

      Put (Result.Task_Name);

      Put (" | ");

      Put (Stack_Size_Blanks & My_Stack_Size_Str);

      Put (" | ");

      Put (Actual_Use_Blanks & Actual_Use_Str);

      New_Line;

   end Output_Result;

   ---------------------

   --  Output_Results --

   ---------------------

   procedure Output_Results is

      Max_Stack_Size                         : Natural := 0;

      Max_Actual_Use_Result_Id               : Natural := Result_Array'First;

      Max_Stack_Size_Len, Max_Actual_Use_Len : Natural := 0;

      Task_Name_Blanks : constant

        String (1 .. Task_Name_Length - Task_Name_Str'Length) :=

          (others => ' ');

   begin

      Set_Output (Standard_Error);

      if Compute_Environment_Task then

         Compute_Result (Environment_Task_Analyzer);

         Report_Result (Environment_Task_Analyzer);

      end if;

      if Result_Array'Length > 0 then

         --  Computes the size of the largest strings that will get displayed,

         --  in order to do correct column alignment.

         for J in Result_Array'Range loop

            exit when J >= Next_Id;

            if Result_Array (J).Value >

               Result_Array (Max_Actual_Use_Result_Id).Value

            then

               Max_Actual_Use_Result_Id := J;

            end if;

            if Result_Array (J).Max_Size > Max_Stack_Size then

               Max_Stack_Size := Result_Array (J).Max_Size;

            end if;

         end loop;

         Max_Stack_Size_Len := Natural'Image (Max_Stack_Size)'Length;

         Max_Actual_Use_Len :=

           Get_Usage_Range (Result_Array (Max_Actual_Use_Result_Id))'Length;

         --  Display the output header. Blanks will be added in front of the

         --  labels if needed.

         declare

            Stack_Size_Blanks  : constant

              String (1 .. Max_Stack_Size_Len - Stack_Size_Str'Length) :=

                (others => ' ');

            Stack_Usage_Blanks : constant

              String (1 .. Max_Actual_Use_Len - Actual_Size_Str'Length) :=

                (others => ' ');

         begin

            if Stack_Size_Str'Length > Max_Stack_Size_Len then

               Max_Stack_Size_Len := Stack_Size_Str'Length;

            end if;

            if Actual_Size_Str'Length > Max_Actual_Use_Len then

               Max_Actual_Use_Len := Actual_Size_Str'Length;

            end if;

            Put

              (Index_Str & " | " & Task_Name_Str & Task_Name_Blanks & " | "

               & Stack_Size_Str & Stack_Size_Blanks & " | "

               & Stack_Usage_Blanks & Actual_Size_Str);

         end;

         New_Line;

         --  Now display the individual results

         for J in Result_Array'Range loop

            exit when J >= Next_Id;

            Output_Result

              (J, Result_Array (J), Max_Stack_Size_Len, Max_Actual_Use_Len);

         end loop;

      --  Case of no result stored, still display the labels

      else

         Put

           (Index_Str & " | " & Task_Name_Str & Task_Name_Blanks & " | "

            & Stack_Size_Str & " | " & Actual_Size_Str);

         New_Line;

      end if;

   end Output_Results;

   -------------------

   -- Report_Result --

   -------------------

   procedure Report_Result (Analyzer : Stack_Analyzer) is

      Result  : Task_Result :=

                  (Task_Name      => Analyzer.Task_Name,

                   Max_Size       => Analyzer.Stack_Size,

                   Variation    => 0,

                   Value    => 0);

      Overflow_Guard : constant Integer :=

        Analyzer.Stack_Size

          - Stack_Size (Analyzer.Top_Pattern_Mark, Analyzer.Bottom_Of_Stack);

      Max, Min : Positive;

   begin

      if Analyzer.Pattern_Size = 0 then

         --  If we have that result, it means that we didn't do any computation

         --  at all. In other words, we used at least everything (and possibly

         --  more).

         Min := Analyzer.Stack_Size - Overflow_Guard;

         Max := Analyzer.Stack_Size;

      else

         Min :=

           Stack_Size

             (Analyzer.Topmost_Touched_Mark, Analyzer.Bottom_Of_Stack);

         Max := Min + Overflow_Guard;

      end if;

      Result.Value := (Max + Min) / 2;

      Result.Variation := (Max - Min) / 2;

      if Analyzer.Result_Id in Result_Array'Range then

         --  If the result can be stored, then store it in Result_Array

         Result_Array (Analyzer.Result_Id) := Result;

      else

         --  If the result cannot be stored, then we display it right away

         declare

            Result_Str_Len : constant Natural :=

                               Get_Usage_Range (Result)'Length;

            Size_Str_Len   : constant Natural :=

                               Natural'Image (Analyzer.Stack_Size)'Length;

            Max_Stack_Size_Len : Natural;

            Max_Actual_Use_Len : Natural;

         begin

            --  Take either the label size or the number image size for the

            --  size of the column "Stack Size".

            Max_Stack_Size_Len :=

              (if Size_Str_Len > Stack_Size_Str'Length

               then Size_Str_Len

               else Stack_Size_Str'Length);

            --  Take either the label size or the number image size for the

            --  size of the column "Stack Usage".

            Max_Actual_Use_Len :=

              (if Result_Str_Len > Actual_Size_Str'Length

               then Result_Str_Len

               else Actual_Size_Str'Length);

            Output_Result

              (Analyzer.Result_Id,

               Result,

               Max_Stack_Size_Len,

               Max_Actual_Use_Len);

         end;

      end if;

   end Report_Result;

end System.Stack_Usage;