[sdcc-devel] [ sdcc-Bugs-1738367 ] bit returned in dpl

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Bugs item #1738367, was opened at 2007-06-16 07:33
Message generated for change (Comment added) made by nobody
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Category: C-Front End
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Maarten Brock (maartenbrock)
Assigned to: Maarten Brock (maartenbrock)
Summary: bit returned in dpl

Initial Comment:
The following code still generates code that returns a bit in dpl for the mcs51.

bit Ternary(unsigned char status)
{
    return (status == 0) ? 0 : 1;
}

_Ternary:
	ar2 = 0x02
	ar3 = 0x03
	ar4 = 0x04
	ar5 = 0x05
	ar6 = 0x06
	ar7 = 0x07
	ar0 = 0x00
	ar1 = 0x01
;	genReceive
;	heaters.c:6: return (status == 0) ? 0 : 1;
;	genNot
;	peephole 177.g	optimized mov sequence
	mov	a,dpl
	mov	r2,a
	cjne	a,#0x01,00105$
00105$:
	clr	a
	rlc	a
;	genNot
	mov	r2,a
;	Peephole 105	removed redundant mov
	cjne	a,#0x01,00106$
00106$:
	clr	a
	rlc	a
	mov	dpl,a
;	genRet
;	Peephole 500	removed redundant label 00101$
	ret

Not to mention the unoptimized code.

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Comment By: Nobody/Anonymous (nobody)
Date: 2007-06-28 04:03

Message:
Logged In: NO 

SDCC : mcs51 2.7.2 # (Jun 28 2007) (UNIX)
svn #4870

still produces incorrect code, for the slightly modified function

bit foo(char arg) {
  return arg & 1;
}

==>

   0000 E5 82               108 	mov	a,dpl
   0002 54 01               109 	anl	a,#0x01
   0004 F5 82               110 	mov	dpl,a
   0006 22                  111 	ret

thus, the function still returns a char in dpl, instead of a bit
  in the carry flag

greetings,
  Robert Larice

larice 0x40 vidisys 0x2e de

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Comment By: Frieder Ferlemann (frief)
Date: 2007-06-20 05:04

Message:
Logged In: YES 
user_id=589052
Originator: NO

I'm attaching a file which allows to reproduce the bug 
within the regression test suite.

Note, older versions of SDCC (I tested with SDCC 2.7.1 #4827) 
pass the test whereas uptodate versions do not.

Greetings,
Frieder
File Added: bug1738367.c

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Comment By: Frieder Ferlemann (frief)
Date: 2007-06-17 01:32

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These would fail too:

return (status == 0) ? 1 : 0;
return !status ? 1 : 0;
return status ? 0 : 1;

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Comment By: Maarten Brock (maartenbrock)
Date: 2007-06-16 14:20

Message:
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user_id=888171
Originator: YES

Seems it was not fixed at all. The following still fails:

return (status == 0) ? (bit)0 : (bit)1;


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Comment By: Maarten Brock (maartenbrock)
Date: 2007-06-16 07:53

Message:
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Originator: YES

Fixed in SDCC 2.7.2 #4854.

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