[sdcc-devel] [ sdcc-Bugs-1029883 ] Problem with pointers as arguments

[SourceForge.net <no...@so...>]

Bugs item #1029883, was opened at 2004-09-17 16:51
Message generated for change (Comment added) made by vrokas
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=100599&aid=1029883&group_id=599

Category: None
Group: fixed
Status: Closed
Resolution: Fixed
Priority: 5
Submitted By: ccsporters (tecodev)
Assigned to: Erik Petrich (epetrich)
Summary: Problem with pointers as arguments

Initial Comment:
Have a look at:

void
test1(unsigned int a)
{
}

void
test2(unsigned int * a)
{
}

int
test(signed int target)
{
  test1(target);
  test2(&target);
  return target;
}

The resulting asm code for test (pic16, but may be a
general problem) is:

**************************************
_test:
#LINE	13; reftest.c	test(signed int target)
	MOVFF	FSR2L, POSTDEC1
	MOVFF	FSR1L, FSR2L
	MOVFF	r0x00, POSTDEC1
	MOVFF	r0x01, POSTDEC1
;;ic:3: _test_target_1_1 [...]{...}{int} = recv 
	BANKSEL	(_test_target_1_1 + 1)
	MOVWF	(_test_target_1_1 + 1), B
	MOVLW	0x02
	MOVFF	PLUSW2, _test_target_1_1
;;ic:4: iTemp0 [.. lr4:10 ..]{...}{unsigned-int}{ sir@
<_test_target_1_1}[r0x00 r0x01 ] := _test_target_1_1
[...]{...}{int}
#LINE	15; reftest.c	test1(target);
	MOVFF	_test_target_1_1, r0x00
	MOVFF	(_test_target_1_1 + 1), r0x01
;;ic:5:	send iTemp0 [...]{...}{unsigned-int}{ sir@
_test_target_1_1}[r0x00 r0x01 ]{argreg = 1}
;;ic:6: iTemp1 [...]{...}{void} = call _test1
[...]{...}{void function    ( unsigned-int) }
	MOVF	r0x00, W
	MOVWF	POSTDEC1
	MOVF	r0x01, W
	CALL	_test1
	MOVLW	0x01
	ADDWF	FSR1L, F
;;ic:7:	iTemp2 [...]{...}{int near* }[remat] =
&[_test_target_1_1 [...]{...}{int}]
;;ic:8: send iTemp2 [...]{...}{int near*
}[remat]{argreg = 1}
;;ic:9:	iTemp4 [...]{...}{void} = call _test2
[...]{...}{void function    ( unsigned-int generic* ) }
#LINE	16; reftest.c	test2(&target);
	MOVLW	LOW(_test_target_1_1)
	MOVWF	POSTDEC1
	MOVLW	HIGH(_test_target_1_1)
	CALL	_test2
	MOVLW	0x01
	ADDWF	FSR1L, F
;;ic:10: ret iTemp0 [.. lr4:10 ..]{...}{unsigned-int}{
sir@ _test_target_1_1}[r0x00 r0x01 ]
#LINE	17; reftest.c	return target;
	MOVFF	r0x01, PRODL
	MOVF	r0x00, W
;;ic:11:  _return($1) :
;;ic:12: eproc _test [...]{...}{int function    ( int) }
	MOVFF	PREINC1, r0x01
	MOVFF	PREINC1, r0x00
	MOVFF	PREINC1, FSR2L
	RETURN	

**************************************

Result: Instead of returning the value of "target",
sdcc thinks it can reuse the old target and ignores the
possibility that test2 changes "target". But:
everything works fine if variable and parameter are of
the same type (twice signed int or twice unsigned int)
or if target is global. We included the iCode output
because the life range of (ic:4)  [lr4:10] seems to be
a bit too long. Why not [lr:4:9]?

SDCC : pic16 2.4.3 #843 (Sep 16 2004) (UNIX)
called with: sdcc -mpic16 -p18f452 --no-crt

Raphael Neider & Daniel Winkler

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

>Comment By: Vangelis Rokas (vrokas)
Date: 2004-09-19 16:34

Message:
Logged In: YES 
user_id=770505

Thanks Erik. I thought initially that this might have been a
problem in the live range estimator. But it was elsewhere.


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

Comment By: Erik Petrich (epetrich)
Date: 2004-09-19 04:16

Message:
Logged In: YES 
user_id=635249

This was a GCSE problem common to all ports.

Fixed with src/SDCCcse.c 1.96 and src/SDCCcse.h 1.11
(SDCC 2.4.4 #845)

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

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=100599&aid=1029883&group_id=599