[sdcc-devel] [ sdcc-Bugs-1491627 ] variable bit shifting results in wrong code in hc08 port

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Bugs item #1491627, was opened at 2006-05-19 14:19
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: kosmonaut_pirx (kosmonaut_pirx)
Assigned to: Nobody/Anonymous (nobody)
Summary: variable bit shifting results in wrong code in hc08 port

Initial Comment:
1. sample code

char CTFLG;

void 
main()
{
  unsigned char bufno = 0; 

  /* this is just to fool the optimizer */
  if ( CTFLG ){
    bufno = 1;
  } else{
    bufno = 2;
  }
  CTFLG = 1 << bufno;
}

2. sdcc command
sdcc --no-peep -I. -I../include -mhc08 --stack-loc
0x044F --out-fmt-s19 --model-large --verbose -V --debug
-c bug_bitshift.c

3. sdcc version
SDCC : hc08 2.5.6 # (May 10 2006) (UNIX)
also in an older version from snapshots:
SDCC : hc08 2.5.4 #1219 (Mar  7 2006) (UNIX)

compiled with only hc08 port:
./configure --disable-mcs51-port --disable-gbz80-port
--disable-z80-port --disable-avr-port
--disable-ds390-port --disable-pic-port
--disable-pic16-port --disable-xa51-port
--disable-ds400-port --disable-ucsim

4. error description
The resulted code run into an infinite loop. 

The reason for this can be found at the appropriate 
lst-file and line:

;bug_bitshift.c:53: CTFLG = 1 << bufno;
 	lda	#0x01
 	sta	_CTFLG
 	lda	_main_bufno_1_1
 	beq	00113$
00112$:
        lda	_CTFLG
        lsla
 	sta	_CTFLG
 	deca
 	bne	00112$
00113$:

The condition for bit shifting is not used in the last
instructions anymore, so it just spins around forever.
No idea for me at the moment about how to solve this
instruction with just on register.

5. email
joe...@gr...








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