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Conference turris::fortran

Title:	Digital Fortran
Notice:	Read notes 1.* for important information
Moderator:	QUARK::LIONEL

Created:	Thu Jun 01 1995
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	1333
Total number of notes:	6734

1317.0. "different results when compile with -g, -g1 or -g3" by MGOF01::HSIMON () Wed May 28 1997 05:59

When I compile the following little fortran program with
-g, -g1 or -g3, I have different results with "print" and
"whatis" using dbx or decladebug.

Any hints?

Hans-Werner

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

dunix 3.2
COMPILER: Digital Fortran 77 V4.1-92-33BL
dbx version 3.11.8
DECladebug Debugger Version 3.0-16

---------- kkk.f ----------------------------------------

      program  kkk
      character*10 otto
      dimension aa(10)
      otto='otto'
      b=3.
      r=a*3.
      write (*,"(2f12.5)")  r,a
      stop
      end

------ f77 -g -o kkk kkk.f ------------------------------

$ dbx kkk
dbx version 3.11.8
Type 'help' for help.

kkk:   4  otto='otto'
(dbx) print r
0.000000                                    <--------- ok
(dbx) whatis aa
 real  AA(1:10)                             <--------- ok
(dbx) q

------ f77 -g -o kkk kkk.f ------------------------------

$ dbx kkk_g1
dbx version 3.11.8
Type 'help' for help.

kkk:   4  otto='otto'
(dbx) print r

"r" is not defined or not active              <-------- ?
(dbx) whatis aa
aa is not defined or not active               <-------- ?
(dbx) q

------ f77 -g -o kkk kkk.f ------------------------------

$ dbx kkk_g3
dbx version 3.11.8
Type 'help' for help.

kkk:   7  write (*,"(2f12.5)")  r,a

warning: Files compiled -g3: parameter values probably wrong
(dbx) print r

R not active                                  <-------- ?
(dbx) whatis aa
 real  AA(1:10)                               <-------- ?
(dbx) q

------ f77 -g -o kkk kkk.f ------------------------------

$ decladebug kkk
Welcome to the DECladebug Debugger Version 3.0-16
------------------ 
object file name: kkk 
Reading symbolic information ...done
(decladebug) print r
0                                            <-------- ok
(decladebug) whatis aa
float (1:10) aa                              <-------- ok
(decladebug) q

------ f77 -g -o kkk kkk.f ------------------------------

$ decladebug kkk_g1
Welcome to the DECladebug Debugger Version 3.0-16
------------------ 
object file name: kkk_g1 
Reading symbolic information ...done
(decladebug) print r
Symbol r undefined.                           <-------- ?
Error: no value for r
(decladebug) whatis aa
Symbol aa undefined.                          <-------- ?
(decladebug) q

------ f77 -g -o kkk kkk.f ------------------------------

$ decladebug kkk_g3
Welcome to the DECladebug Debugger Version 3.0-16
------------------ 
object file name: kkk_g3 
Reading symbolic information ...done
(decladebug) print r
Symbol r not visible in current scope.        <-------- ?
Error: no value for r
(decladebug) whatis aa
Symbol aa not visible in current scope.       <-------- ?
(decladebug) q

T.R Title User Personal
Name Date Lines

1317.1 Watch the optimisation level HERON::BLOMBERG Trapped inside the universe Wed May 28 1997 07:14 11

T.R	Title	User	Personal Name	Date	Lines
1317.1	Watch the optimisation level	HERON::BLOMBERG	Trapped inside the universe	`Wed May 28 1997 07:14`	11
	First of all you are using "a" before it's defined. Depending on the degree of optimisation, your variables might be optimised away. Compiling -g enforces -O0 if you don't specify anything else, that's why the results "look ok". Try compiling -g -O4 and -g3 -O0 and see how the results vary with the degree of optimisation. /Ake

    
    
            First of all you are using "a" before it's defined.
    
            Depending on the degree of optimisation, your variables might
            be optimised away. Compiling -g enforces -O0 if you don't
            specify anything else, that's why the results "look ok".
            Try compiling -g -O4 and -g3 -O0 and see how the results
            vary with the degree of optimisation.
    
    /Ake