From: Dave Brolley <brolley@redhat.com>
To: "Frank Ch. Eigler" <fche@redhat.com>
Cc: cgen@sources.redhat.com
Subject: Re: escaping in syntax strings
Date: Mon, 26 Mar 2001 09:11:00 -0000 [thread overview]
Message-ID: <3ABF7866.40608@redhat.com> (raw)
In-Reply-To: <o5snk01nnf.fsf@toenail.toronto.redhat.com>
Yes -- see the fr30 for an example of this:
h-r13 -- hardware element
R13 -- special operand
r13base-ld -- pmacro for generating insns which have r13 hardwired but
still specified
Dave
Frank Ch. Eigler wrote:
> I wrote:
>
> : [...]
> : By the way, why do you need a "$" in the syntax string? Are you
> : confusing register name keywords or hexadecimal constants with
> : the markers that actually belong into the syntax strings?
>
> I just found what Ben was talking about. It seems that some
> instructions in the assembly language for his target includes dummy
> operands that make explicit the implicit (not-encoded) operands. For
> example, given a register keyword set such as "$0 .. $7", there are
> some instructions which are hard-wired to use only $0 as an input or
> output, in addition to other inputs/outputs. Rather than leave the $0
> implicit, this assembly language expects the programmer to specify it.
> Say,
> compare $0,$2,$3
> instead of
> compare $2,$3
>
> So, Ben is trying to implement this in the assembler by including the
> literal string "$0" in the syntax bytes of the instruction. This is
> not too bad, though a possibly better way would be to associate a
> synthetic cgen operand with that slot, and to give it a parser that
> accepts only "$0", and emits a helpful error message for anything
> else.
>
> - FChE
>
>
next prev parent reply other threads:[~2001-03-26 9:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-03-25 20:16 Ben Elliston
2001-03-26 5:10 ` Frank Ch. Eigler
2001-03-26 5:22 ` Ben Elliston
[not found] ` <15039.17056.78350.71117.cygnus.local.cgen@scooby.apac.redhat.com>
2001-03-26 8:30 ` Frank Ch. Eigler
[not found] ` <o5wv9c1ojl.fsf.cygnus.local.cgen@toenail.toronto.redhat.com>
2001-03-26 8:49 ` Frank Ch. Eigler
2001-03-26 9:11 ` Dave Brolley [this message]
2001-03-26 14:08 ` Ben Elliston
2001-03-26 14:15 ` Dave Brolley
2001-03-26 14:21 ` Frank Ch. Eigler
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