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From: rmariani@watmum.UUCP (Rico Mariani)
Newsgroups: comp.sys.amiga
Subject: More bugs... or is it the same bug hiding in slightly different code
Message-ID: <723@watmum.UUCP>
Date: Sat, 6-Dec-86 15:57:18 EST
Article-I.D.: watmum.723
Posted: Sat Dec  6 15:57:18 1986
Date-Received: Sun, 7-Dec-86 04:17:34 EST
Distribution: net
Organization: U of Waterloo, Ontario
Lines: 76

Could someone check to see if this code compiles OK under V3.30 or higher
of Aztec?  It gives the same kind of bug as the last bit of code, error
at assembly time

main()
{
	int  box[1], i;

	(box+i)[0] =
	(box+i)[0] =
	(box+i)[0] =
	(box+i*i)[0] = 0;
}

It's very subtle, as any tweaking of the above results in a correct
compilation, e.g. if you delete one of the redundant assignments it's
just fine...

This is so similar to the other bug that it just might have been corrected
along with it, but just in case (and as a further confidence test...)

On the whole, I've thrown a big mess of the ugliest C source you could
imagine at Aztec and it has compiled most of it without problems.  I'm
very impressed...


	-Rico

Here's the assembler that the above code generates.

;:ts=8
;main()
;{
	public	_main
_main:
	link	a5,#.2
	movem.l	.3,-(sp)
;	int  box[1], i;
;
;	(box+i)[0] =
;	(box+i)[0] =
;	(box+i)[0] =
;	(box+i*i)[0] = 0;
	move.l	-8(a5),d3
	asl.l	#2,d3
	lea	-4(a5),a6
	move.l	-8(a5),d2
	asl.l	#2,d2		<--- this value is already in d3
	lea	-4(a5),a1	<--- this one is in a6...
	move.l	-8(a5),d1	
	asl.l	#2,d1		<--- and again
	lea	-4(a5),a0	<--- with both values...
	move.l	-8(a5),d0
	move.l	d1,-(sp)
	move.l	-8(a5),d1
	jsr	.mulu#		<--- perfectly reasonable mulu call this time
	asl.l	#2,d0
	move.l	a6,-(sp)	<--- compiler doesn't know that it doesn't
	lea	-4(a5),a6	     have to save this...
	clr.l	(a6,d0.l)
	clr.l	(a0,.l)		<---- look familiar ??
	clr.l	(a1,d2.l)
	move.l	(sp)+,a6
	move.l	(sp)+,d1
	clr.l	(a6,d3.l)
;}
.4
	movem.l	(sp)+,.3
	unlk	a5
	rts
.2	equ	-8
.3	reg	
	public	.begin
	dseg
	cseg
	end