[sdcc-devel] [ sdcc-Bugs-3389244 ] [PIC14] logical problem - if then - vs - if then else

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Bugs item #3389244, was opened at 2011-08-09 22:57
Message generated for change (Comment added) made by galzsolt
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Category: pic14 target
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Gál Zsolt (galzsolt)
Assigned to: Nobody/Anonymous (nobody)
Summary: [PIC14] logical problem - if then - vs - if then else

Initial Comment:
SDCC : pic16/pic14 3.0.4 #6726 (Aug  9 2011) (Linux)

There is problem in logical function where i use bit variables . 
Here is the two tipical syntax, first whithout else:
 
if ( condition ) {
   expr_set1;
}

And with else:

if ( condition ) {
   expr_set1;
}
else  {
   expr_set2;
}

If I use "if" with "else" the compiled code is correct. If I don't use "else" the compiled code doesn't follow the original logic. 
I attached an example which will show clearly the differece. 

I wanted to make logical OR function but this compiled code doesen't follow it:

	.line	39; "logical_test.c"	if( B0 && B2 )
	BTFSS	_b,0

	GOTO	_00118_DS_

	BTFSS	_b,2

	.line	41; "logical_test.c"	if( !B1 || !B3 ) B4 = 1;
	GOTO	_00118_DS_
	BTFSC	_b,1
	BTFSS	_b,3
	BSF	_b,4
_00118_DS_

And the well working result with "else":

	.line	31; "logical_test.c"	if( B0 && B2 )
	BTFSS	_b,0
	GOTO	_00109_DS_
	BTFSS	_b,2
	GOTO	_00109_DS_
	BTFSS	_b,1
	GOTO	_00105_DS_
	BTFSC	_b,3
	GOTO	_00110_DS_

_00105_DS_
	BANKSEL	_b
	BSF	_b,4
	GOTO	_00110_DS_

_00109_DS_

	.line	35; "logical_test.c"	else B4 = 0;
	BANKSEL	_b
	BCF	_b,4

_00110_DS_
	.line	38; "logical_test.c"	B4 = 0;
	BANKSEL	_b
	BCF	_b,4

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>Comment By: Gál Zsolt (galzsolt)
Date: 2011-08-10 00:20

Message:
Sorry for confusion. I wasn't enough attentive and I complained about a
well working code. So here is the problematic code:

	.line	23; "logical_test.c"	b.common_byte = 0x0B;
	MOVLW	0x0b
	BANKSEL	_b
	MOVWF	(_b + 0)
	
	.line	25; "logical_test.c"	b.B4 = 0;
	BCF	_b,4
	
	.line	26; "logical_test.c"	if( b.B0 && b.B1 )
	BTFSS	_b,0
	GOTO	_00001_DS_
	BTFSS	_b,1

	.line	28; "logical_test.c"	if( !b.B2 || !b.B3 ) c.B0 = 1;
	GOTO	_00001_DS_
	BTFSC	_b,2
	BTFSC	_b,3
	GOTO	_00001_DS_
	BANKSEL	_c
	BSF	_c,0
_00001_DS_
	RETURN	

And I attached the source of it. I tested it by GPsim whith the following
inputs in "b":
0x03 -> result: c = 0 ( it should be 1 )
0x07 -> result: c = 1 
0x0B -> result: c = 0 ( it should be 1 )
0x0F -> result: c = 1 ( it should be 0 )

If I uncomment the "else NOP" line I get the correct result for these
inputs.

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

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