Alcyon C compiler bugs

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Article #380

#380

From: Jan Gray
Date: Fri, 11 Apr 1986 22:57

35 lines
1266 bytes

Hello, I ran across a nasty C compiler bug the other day:

The C source:
	struct foo {
		...
		unsigned array[1];	/* 8 bytes from start of struct */
	};

	func()
	{
		register struct foo	*baz;
		register unsigned	index;

		... = baz->array[index];
	}

generated:
	...
	<move baz into a0>
	<move index into d0>
	swap	d0
	clr	d0
	swap	d0
	clr	d0		<- no matter what index was, it's now 0!
	mov	8(a0,d0),d0
	...

So beware using register unsigned's as array indices.

Surely you other developers out there have compiled a list of bugs to
avoid...could you please post them to the net to save everyone from hardship?

Forced to read the .s output files,

Jan Gray	Looking Glass Software, Waterloo, Ont.	    (519) 884-7473

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Message-ID: <521@looking.UUCP>

Path: arc1-ca.pugleaf.net!utzoo!watmath!looking!jan

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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site looking.UUCP
Path: arc1-ca.pugleaf.net!utzoo!watmath!looking!jan
From: jan@looking.UUCP (Jan Gray)
Newsgroups: net.micro.atari16
Subject: Alcyon C compiler bugs
Message-ID: <521@looking.UUCP>
Date: Fri, 11-Apr-86 17:57:19 EST
Article-I.D.: looking.521
Posted: Fri Apr 11 17:57:19 1986
Date-Received: Sat, 12-Apr-86 02:25:12 EST
Distribution: net
Organization: Looking Glass Software Ltd. Waterloo, Ontario
Lines: 35