From: Taylor Simpson <tsimpson@quicinc.com>
To: Richard Henderson <richard.henderson@linaro.org>,
Alessandro Di Federico <ale.qemu@rev.ng>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: "babush@rev.ng" <babush@rev.ng>, Brian Cain <bcain@quicinc.com>,
Alessandro Di Federico <ale@rev.ng>,
"nizzo@rev.ng" <nizzo@rev.ng>,
"philmd@redhat.com" <philmd@redhat.com>
Subject: RE: [PATCH v2 02/10] target/hexagon: import README for idef-parser
Date: Wed, 10 Mar 2021 15:48:14 +0000 [thread overview]
Message-ID: <BYAPR02MB48867812389A9AE6031D7215DE919@BYAPR02MB4886.namprd02.prod.outlook.com> (raw)
In-Reply-To: <3b3c6088-0ff2-beeb-e9fe-29c2dec012ca@linaro.org>
> -----Original Message-----
> From: Richard Henderson <richard.henderson@linaro.org>
> Sent: Thursday, February 25, 2021 2:21 PM
> To: Alessandro Di Federico <ale.qemu@rev.ng>; qemu-devel@nongnu.org
> Cc: Taylor Simpson <tsimpson@quicinc.com>; Brian Cain
> <bcain@quicinc.com>; babush@rev.ng; nizzo@rev.ng; philmd@redhat.com;
> Alessandro Di Federico <ale@rev.ng>
> Subject: Re: [PATCH v2 02/10] target/hexagon: import README for idef-
> parser
>
> On 2/25/21 7:18 AM, Alessandro Di Federico wrote:
> > +Now let's have a quick look at the generated code, line by line.
> > +
> > +::
> > +
> > + tcg_gen_movi_i32(RdV, 0);
> > +
> > +This code starts by initializing ``RdV``, since reading from that register
> > +without initialization will cause a segmentation fault by QEMU. This is
> emitted
> > +because a declaration of the ``RdV`` register was parsed, but no reading of
> the
> > +``RdV`` register was found.
>
> This is odd, as is the description of why. Yes, if RdV is read without
> initialization, TCG middle-end will abort (at least with --enable-debug-tcg
> enabling the assertions). But you've just said that "no reading" was found.
> So why did you perform this dummy initialization, which will be eliminated
> later?
Which instructions require this? There must be an attribute that we could check to see if it is needed before emitting the TCG.
Taylor
next prev parent reply other threads:[~2021-03-10 15:51 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-25 15:18 [PATCH v2 00/10] target/hexagon: introduce idef-parser Alessandro Di Federico via
2021-02-25 15:18 ` [PATCH v2 01/10] target/hexagon: update MAINTAINERS for idef-parser Alessandro Di Federico via
2021-02-25 20:46 ` Richard Henderson
2021-02-25 15:18 ` [PATCH v2 02/10] target/hexagon: import README " Alessandro Di Federico via
2021-02-25 20:20 ` Richard Henderson
2021-03-01 14:50 ` Alessandro Di Federico via
2021-03-10 15:48 ` Taylor Simpson [this message]
2021-03-18 17:26 ` Alessandro Di Federico via
2021-04-05 21:26 ` Taylor Simpson
2021-02-25 15:18 ` [PATCH v2 03/10] target/hexagon: make helper functions non-static Alessandro Di Federico via
2021-02-25 20:47 ` Richard Henderson
2021-02-25 15:18 ` [PATCH v2 04/10] target/hexagon: introduce new helper functions Alessandro Di Federico via
2021-02-25 20:45 ` Richard Henderson
2021-02-25 15:18 ` [PATCH v2 05/10] target/hexagon: expose next PC in DisasContext Alessandro Di Federico via
2021-02-25 20:48 ` Richard Henderson
2021-02-25 15:18 ` [PATCH v2 06/10] target/hexagon: prepare input for the idef-parser Alessandro Di Federico via
2021-02-25 21:34 ` Richard Henderson
2021-03-01 16:26 ` Paolo Montesel via
2021-02-25 15:18 ` [PATCH v2 07/10] target/hexagon: import lexer for idef-parser Alessandro Di Federico via
2021-02-25 22:24 ` Richard Henderson
2021-02-25 15:18 ` [PATCH v2 08/10] target/hexagon: import parser " Alessandro Di Federico via
2021-02-26 3:30 ` Richard Henderson
2021-03-01 14:50 ` Alessandro Di Federico via
2021-03-23 16:52 ` Paolo Montesel via
2021-02-25 15:18 ` [PATCH v2 09/10] target/hexagon: call idef-parser functions Alessandro Di Federico via
2021-02-26 3:47 ` Richard Henderson
2021-03-01 14:49 ` Alessandro Di Federico via
2021-02-25 15:18 ` [PATCH v2 10/10] target/hexagon: import additional tests Alessandro Di Federico via
2021-02-26 3:52 ` Richard Henderson
2021-02-25 16:03 ` [PATCH v2 00/10] target/hexagon: introduce idef-parser no-reply
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