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Re: Illegal insn due to system register
- From: Joern Rennecke <joern dot rennecke at superh dot com>
- To: "Rakesh Kumar - Software, Noida" <rakeshku at noida dot hcltech dot com>
- Cc: bug-gcc at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org
- Date: Wed, 21 May 2003 13:52:03 +0100
- Subject: Re: Illegal insn due to system register
- Organization: SuperH UK Ltd.
- References: <E04CF3F88ACBD5119EFE00508BBB2121095E0D6F@exch-01.noida.hcltech.com>
"Rakesh Kumar - Software, Noida" wrote:
> Thanks for the reply and the fix. It is working fine with
> BUG.i. But I could not understand why you are returning 9
> from the function sh_register_move_cost. In any case, the insn
> moving MACL to FP register, or otherwise, is illegal,
> and it should be prevented. Let me know if this fix could
> fail in any unfavourable condition.
Well, we return 7 for moves between FPUL and MAC registers,
and FP regs are just one step away from FPUL.
REGISTER_MOVE_COST defines the cost to move data from register
in one class into a register of another class. This can be
done in a single, direct move, or it can through one or more
intermediate registers. If the cost is 2, reload will assume
that a single, direct move is possible, and won't bother to
look if the instruction needs fixing up. Defining any higher
cost will make it inspect the instruction.
> As far as I know, only SH5 has vector moves. Why are we required
> to handle them for SH4 and other targets?
The SH4 can move V2SF vectors, and has instrutions to multiply V4SF
vectors.
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