[M3commit] CVS Update: cm3

[Tony Hosking]

Jay,  I think your usage of TInt and TWord is strongly at odds with its intended use.  Certainly, allowing TInt.Add/Subtract to overflow will break large swaths of the front-end.  There is a deep contract there that requires that TInt arithmetic not provide bogus results.


Antony Hosking | Associate Professor | Computer Science | Purdue University
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On 10 Feb 2010, at 12:58, Jay Krell wrote:

> CVSROOT:	/usr/cvs
> Changes by:	jkrell at birch.	10/02/10 12:58:11
> 
> Modified files:
> 	cm3/m3-sys/m3back/src/: Stackx86.m3 
> 
> Log message:
> 	allow negating FIRST(INTEGER) even though it overflows
> 	allows this test case to compile:
> 	C:\dev2\cm3.2\m3-sys\m3tests\src\p1\p137>cm3
> 	--- building in NT386 ---
> 	
> 	new source -> compiling Main.m3
> 	"..\Main.m3", line 35: doneg: Negate overflowed
> 	1 error encountered
> 	compilation failed => not building program "pgm.exe"
> 	Fatal Error: package build failed
> 	
> 	tempting to make TInt.Add/Subtract return the value
> 	even if overflow, but for now, no.
> 	This fix assumes two's complement, that is,
> 	it assumes FIRST(INTEGER) = -FIRST(INTEGER)

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