Re: [Patch] / 0 should send SIGFPE not SIGTRAP...

[David Daney <ddaney@avtrex.com>]

Maciej W. Rozycki wrote:

>On Fri, 11 Jun 2004 cgd@broadcom.com wrote:
>
>  
>
>>in retrospect, the 'B' variation probably wasn't the greatest idea.
>>
>>If it were removed (leaving 'c' and 'c','q' variations), I don't know
>>that any real harm would occur.
>>
>>It may be very confusing to people who expect that the break code will
>>translate into the instruction in an obvious way, and obviously it
>>would mess up use of 20-bit codes, but i don't know how prevalent that
>>is.
>>
>>Unfortunately, at this point, Linux should probably accept the
>>divide-by-zero code in both locations.
>>
>>
>>(Really, from day one, assemblers probably should have accepted a
>>20-bit code.  I just checked my copy of the Kane r2000/r3000 book, and
>>it was 20-bit all the way back then.  If i had to guess, i'd guess
>>that gas was copying a non-gnu assembler's behaviour.  In any case,
>>water under the bridge.)
>>    
>>
>
> As it's at least annoying to have different break codes for divisions 
>expanded by gcc explicitly and ones created implicitly by gas, here's the 
>most reasonable (IMO) approach to fix that.  I think it should have been 
>implemented this way originally (if at all).
>
>gas/testsuite/:
>2004-06-22  Maciej W. Rozycki  <macro@ds2.pg.gda.pl>
>
>	* gas/mips/break20.s: Test the "break20" alias.
>	* gas/mips/break20.d: Results for the test.
>	* gas/mips/mips32.s: Replace "break" with "break20".
>	* gas/mips/set-arch.s: Likewise.
>	* gas/mips/mips32.d: Adjust for the new output.
>	* gas/mips/set-arch.d: Likewise.
>
>opcodes/:
>2004-06-22  Maciej W. Rozycki  <macro@ds2.pg.gda.pl>
>
>	* mips-opc.c (mips_builtin_opcodes): Replace the MIPS32 ISA 
>	specific "break" encoding with a "break20" alias accepted for any 
>	ISA.
>
>  
>
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Just out of curiosity, do you propose this patch in lieu of the patch to 
Linux's traps.c?

Or would you do both?

It seems like both would be best, as there are already "broken" binutils 
floating around out there.

Also nobody has objected to the kernel patch...

David Daney.