Confused about data types [SOLVED].

[giorgos]

Hi! :-)

I was trying to rewrite an older program with arrays, in a more modern way, but I got stuck on the way! :-)
To start with basics, lets take a tiny program, that reads 2 numbers (from keyboard), and adds them (and then displaying the result on screen).

Code: Select all

DIM AS UBYTE NR(2), Z, N
FOR N=1 TO 2
INPUT NR(N)
PRINT NR(N)
NEXT
PRINT "----------------"
PRINT NR(1)
PRINT NR(2)
PRINT "----------------"
PRINT "SUM"
Z=NR(1)+NR(2)
PRINT Z


So far, so good!
(At least, I think so)! :-)
The only problem is, that the above program, works with integers.

Lets rewrite it, so it will work with real numbers:

Code: Select all

DIM AS UBYTE N
DIM AS SINGLE NR(2), Z
FOR N=1 TO 2
INPUT NR(N)
PRINT NR(N)
NEXT
PRINT "----------------"
PRINT NR(1)
PRINT NR(2)
PRINT "----------------"
PRINT "SUM"
Z=NR(1)+NR(2)
PRINT Z

Nope! It doesn't adds. Just displaying the 1st number.
Ehm...Am I missing something???
TIA!!! :-)
G.

[MrSwiss]

I don't find a problem, if compiled with default language (-lang FB)?!?

If you are using another dialect, please specify ...

FB's standard data-types: CatPgStdDataTypes

[badidea]

Works perfectly fine here as well:

Code: Select all

? 2.34
 2.34
? -13.7
-13.7
----------------
 2.34
-13.7
----------------
SUM
-11.36


The only problem I can think of is that you are not running the executable that belongs to that code.
Running a freebasic code requires 2 steps: 1. compilation 2. execution
If step 1 fails or is skipped for some reason (virus-scanner?), it can be that you keep running a previous compiled (buggy) version.
Try to delete the executable (e.g. hello.exe) and try compilation and run/execute again.

[giorgos]

THANKS guys!!! :-)
I think I found, the source of the problem:
It was the command line argument -vec 2 (who was never troubled me, till today).
Switching it to 1, solved the problem.

I admit, I don't know the internals of FB!
Do you think, it's a bug?

[MrSwiss]

-vec < level >

Set level of vector optimizations enabled by the compiler (default: 0)

I've never used this: Compiler Option
Dunno, what it is supposed to be good for, anyway. (don't think it's a bug, though)

[fxm]

This is not the first time that fbc has encountered a problem with the use of '-fpu sse -vec 2':
See for example viewtopic.php?f=17&t=21960

[giorgos]

Well...indeed it's a bug and it's already reported:
https://sourceforge.net/p/fbc/bugs/572/

No need for further actions.
Bye!!! :-)
G.

[fxm]

Yes, this bug report comes from this thread: viewtopic.php?f=3&t=19271

[SARG]

-vec 2 enables intra-expression vectorization.

Not sure but it seems this functionnality is not completly implemented.
In the function extracted from ast-vectorize.bas (see end of post) only add operator appears, no sub or others. Why ?

So Z=NR(1)-NR(2) works perfectly.

Code: Select all

##Z=NR(1)-NR(2)
   movss xmm6, [ebp-16]
   subss xmm6, dword ptr [ebp-12]
   movss [ebp-56], xmm6

With -vec 2

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##Z=NR(1)+NR(2)
   movss xmm6, [ebp-16]
               <----- missing line that exists if vec 1, see below
   movss [ebp-56], xmm6

But with -vec 1

Code: Select all

##Z=NR(1)+NR(2)
   movss xmm6, [ebp-16]
   addss xmm6, dword ptr [ebp-12]
   movss [ebp-56], xmm6

With simple variables no problem : z=f1 + f2 but with arrays and udt fields (as reported in the bug list) it doesn't work.
After quickly looking at the code it could be an error when comparing addresses of the variables involved in the statement.
If I have the time I will try to confirm the cause of the bug.

Code: Select all

private function astIntraTreeVectorize _
   ( _
      byval n as ASTNODE ptr _
   ) as integer

   dim as ASTNODE ptr l = any
   dim as integer changed = FALSE

   if( n = NULL ) then return FALSE

   if( n->class = AST_NODECLASS_BOP ) then
      if( n->op.op = AST_OP_ADD ) then                       <--------------------------------------- Only add

         maxVectorWidth = 4
         vectorWidth = 0
         if( hMergeNode( n->l, n->r, FALSE ) ) then
            maxVectorWidth = 4
            vectorWidth = 0
            hMergeNode( n->l, n->r, TRUE )

            '' check for multiple HADDs
            l = n->l
            if( l->class = AST_NODECLASS_UOP ) then
               if( l->op.op = AST_OP_HADD ) then
                  *n = *l
                  '' remove this node
                  astDelNode( l )
                  n->vector = 0
                  return TRUE
               end if
            end if

            astDelTree( n->r )
            n->r = NULL
            n->class = AST_NODECLASS_UOP
            n->op.op = AST_OP_HADD
            n->vector = 0

            return TRUE
         end if
      end if
   end if
   if( astIntraTreeVectorize( n->l ) = TRUE ) then
      changed = TRUE
   end if

   if( astIntraTreeVectorize( n->r ) = TRUE ) then
      changed = TRUE
   end if

   function = changed
end function