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Re: RFA: Mark DIVS and DIVU SH2A instructions as unusable in delayslots
- From: Nick Clifton <nickc at redhat dot com>
- To: Joern RENNECKE <joern dot rennecke at st dot com>
- Cc: aoliva at redhat dot com, gcc-patches at gcc dot gnu dot org
- Date: Wed, 12 Jan 2005 10:33:46 +0000
- Subject: Re: RFA: Mark DIVS and DIVU SH2A instructions as unusable in delayslots
- References: <firstname.lastname@example.org> <41E43AAC.email@example.com>
> the processor doesn't allow these instructions in a delay slot at all?
The problem is that the SH2A's "divs" and "divu" instructions should
not be placed into the delay slot of a branch/jump instruction
because they might cause an exception. This is caught by the
simulator which was how the problem was uncovered.
Does that mean that exceptions thrown by a div[su] instruction in a
delay slot need special handling by the exception handler[s], or that
My understanding is that this processor does not allow these
instructions in the delay slots at all. Or rather that the presence of
such instructions in the delay slot is illegal and their behaviour will
be undefined. This was confirmed for us by Allan Tajii of Renesas.