From: DJ Delorie <dj@redhat.com>
To: Richard Sandiford <richard.sandiford@arm.com>
Cc: Franz.Sirl-kernel@lauterbach.com, segher@kernel.crashing.org,
gcc-patches@gcc.gnu.org, richard.sandiford@arm.com
Subject: Re: Remove mode argument from gen_rtx_SET
Date: Mon, 11 May 2015 16:55:00 -0000 [thread overview]
Message-ID: <201505111655.t4BGtGSp023167@greed.delorie.com> (raw)
In-Reply-To: <87zj5e13jn.fsf@e105548-lin.cambridge.arm.com> (message from Richard Sandiford on Sat, 09 May 2015 10:52:12 +0100)
> What I was confused about is that the first set isn't valid rtl.
> The SET_SRC and SET_DEST always have to have the same mode
> (or VOIDmode in the case of a CONST_INT, etc., where the mode
> is implicitly the same as the SET_DEST). So wouldn't it have
> to be:
>
> (set (reg:SI 1)
> (subreg:SI (reg:PSI 2)))
>
> or:
>
> (set (reg:PSI 1)
> (subreg:PSI (reg:SI 2)))
>
> ?
If my memory doesn't match reality, I blame my memory.
I'd have to experiment a while to dig out the details, but the key
point is that a PSI in a reg is not stored the same as a PSI subreg of
an SI reg. You have to keep that information across subregs or you
lose track of where the actual bits are.
prev parent reply other threads:[~2015-05-11 16:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-07 11:37 Richard Sandiford
2015-05-07 13:36 ` Jeff Law
2015-05-07 14:00 ` Richard Sandiford
2015-05-07 15:05 ` Jeff Law
2015-05-08 10:32 ` Franz Sirl
2015-05-08 11:58 ` Segher Boessenkool
2015-05-08 12:52 ` Franz Sirl
2015-05-08 14:03 ` Richard Sandiford
2015-05-08 16:43 ` DJ Delorie
2015-05-09 9:52 ` Richard Sandiford
2015-05-11 16:55 ` DJ Delorie [this message]
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