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Re: Need help restricting a shift instruction's shift count operand to a specific general purpose register
- From: Richard Henderson <rth at redhat dot com>
- To: Mike Laman <mlaman at cox dot net>
- Cc: GCC <gcc at gcc dot gnu dot org>
- Date: Sun, 6 Oct 2002 13:41:57 -0700
- Subject: Re: Need help restricting a shift instruction's shift count operand to a specific general purpose register
- References: <003c01c26d06$9403e5f0$5aa80844@fed1.sdca.home.com>
On Sun, Oct 06, 2002 at 12:04:13AM -0700, Mike Laman wrote:
> 1) as an immediate (constant) value or 2) as a register value that
> can be in any of the general purpose registers EXCEPT register 0.
[...]
> Please point me at some examples of similar instruction restrictions in "md"
> files!
The rs6000 BASE_REGS register class; constraint letter 'b'.
Register 0 is not valid in some arithmetic instructions.
r~