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From: dale@amiga.UUCP (Dale Luck)
Newsgroups: net.micro.amiga
Subject: Re: Re: LATTICE BUG (3.03)	-unsigned? short optimization bug
Message-ID: <1582@amiga.amiga.UUCP>
Date: Wed, 15-Oct-86 17:00:43 EDT
Article-I.D.: amiga.1582
Posted: Wed Oct 15 17:00:43 1986
Date-Received: Thu, 16-Oct-86 18:57:46 EDT
References: <8610111659.AA11477@cory.Berkeley.EDU>
Reply-To: dale@tooter.UUCP (Dale Luck)
Organization: Commodore-Amiga Inc., 983 University Ave #D, Los Gatos CA 95030
Lines: 23

In article <8610111659.AA11477@cory.Berkeley.EDU> dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
>>Actually, I wonder about this.  Shouldn't the expected result be zero?
>>
>>The partial sum (y+z) should be done completely in ushort, giving
>>      0xFFFF + 0x0002  = 0x0001 (retaining only the lower 16 bits)
>>
>>so that the quotient (1/16) [done in integer math] should be zero.
>>I don't see any reason why the code generated for "x=..." and "xx=..."
>>should differ.
>>
>>Am I missing something here?
>
>	All integral arguments, baring floating expressions, for arithmatic 
>operations are supposed to be extended to INT if they are <= INT.  On Lattice,
>this is 32bits.
>
>						-Matt
>	
However this is pretty poor coding practice. If you expected the results
to overflow a 16bit the programmer should have made allowances for this.
It's those kind of problems that give compiler writers a severe headache
when trying to do some intelligeant optimizing code generation.
Dale Luck