[14] RFR(S): 8234583: PrintAssemblyOptions isn't passed to hsdis library
Schmidt, Lutz
lutz.schmidt at sap.com
Tue Nov 26 09:25:33 UTC 2019
Thank you, Jean-Philippe, for checking once again.
Regards,
Lutz
From: Jean-Philippe BEMPEL <jean-philippe at bempel.fr>
Date: Tuesday, 26. November 2019 at 10:19
To: Lutz Schmidt <lutz.schmidt at sap.com>
Cc: Vladimir Ivanov <vladimir.x.ivanov at oracle.com>, "hotspot-compiler-dev at openjdk.java.net" <hotspot-compiler-dev at openjdk.java.net>
Subject: Re: [14] RFR(S): 8234583: PrintAssemblyOptions isn't passed to hsdis library
Hello,
With last review, still works for me.
Thanks
On Mon, Nov 25, 2019 at 9:47 PM Schmidt, Lutz <lutz.schmidt at sap.com<mailto:lutz.schmidt at sap.com>> wrote:
Thanks for the review, Vladimir!
Still one to go.
Regards,
Lutz
On 25.11.19, 21:26, "Vladimir Ivanov" <vladimir.x.ivanov at oracle.com<mailto:vladimir.x.ivanov at oracle.com>> wrote:
> All your other comments are valid. There is an open bug to address and improve the very basic options parsing: https://bugs.openjdk.java.net/browse/JDK-8223765 This task was split off from JDK-8213084.
>
> I would like to cover the improvements you suggest when working on that bug. To make _print_raw work correctly, I suggest to just move
> if (_optionsParsed) return;
> a bit further down. The help text should be printed only once anyway.
Ok, I'm fine with addressing it later. And thanks for taking care of it.
> Here is a new webrev iteration. It reflects what I suggest: https://cr.openjdk.java.net/~lucy/webrevs/8234583.01/
Looks good.
Best regards,
Vladimir Ivanov
> On 25.11.19, 19:30, "Vladimir Ivanov" <vladimir.x.ivanov at oracle.com<mailto:vladimir.x.ivanov at oracle.com>> wrote:
>
> Thanks for the clarifications, Lutz.
>
> So, I assume you have a typo in the patch then:
>
> + if ((options() == NULL) || (strlen(options()) == 0)) {
> + // We need to fill the options buffer for each newly created
> + // decode_env instance. The hsdis_* library looks for options
> + // in that buffer.
> + collect_options(Disassembler::pd_cpu_opts());
> + collect_options(PrintAssemblyOptions);
> + }
>
> It performs collect_options() calls only if _option_buf is either NULL
> or "\0".
>
> Also, what about the following updates of instance members?
>
> if (strstr(options(), "print-raw")) {
> _print_raw = (strstr(options(), "xml") ? 2 : 1);
> }
>
> if (strstr(options(), "help")) {
> _print_help = true;
> }
>
> BTW should _print_help (along with _helpPrinted) be better turned into
> static member?
>
> Can we make _option_buf static as well? Or do we want to keep a
> defensive copy to pass into hsdis.so?
>
> As an alternative approach to fix the bug, we could create a golden copy
> during parsing instead and then just copy it to _option_buf as part of
> decode_env initialization.
>
> Best regards,
> Vladimir Ivanov
>
> On 25.11.2019 19:59, Schmidt, Lutz wrote:
> > Hi Vladimir,
> >
> > I'm happy to elaborate in more detail about the issue and the fix.
> >
> > For each decode_env instance which is constructed, process_options() is called. It collects the disassembly options from various sources (Disassembler::pd_cpu_opts() and PrintAssemblyOptions), storing them in the private member "char _option_buf[512]".
> >
> > Further processing derives static flag settings from these options. Being static, these flags need to be set only once, not every time a decode_env is constructed.
> >
> > But that's just one part of the story. It was not taken into account that _option_buf is passed to and analyzed by hsdis-<platform>.so as well. That requires _option_buf to be filled every time a decode_env is constructed.
> >
> > Moving
> > if (_optionsParsed) return;
> > after the collect_options() calls heals this deficiency.
> >
> > I added the guards you question as additional "safety net". After looking at the code again I must admit the guards are not necessary. _option_buf can never be NULL and every invocation of process_options() is directly preceded by a memset(_option_buf, 0, sizeof(_option_buf)). I can remove the guards if you like.
> >
> > Please let me know if there are any more questions to be answered.
> >
> > Thanks,
> > Lutz
> >
> >
> > On 25.11.19, 17:05, "Vladimir Ivanov" <vladimir.x.ivanov at oracle.com<mailto:vladimir.x.ivanov at oracle.com>> wrote:
> >
> > Lutz,
> >
> > Can you elaborate, please, how the patch fixes the problem?
> >
> > Why did you decide to add the following guards?
> >
> > + if ((options() == NULL) || (strlen(options()) == 0)) {
> >
> > Best regards,
> > Vladimir Ivanov
> >
> > On 25.11.2019 17:06, Schmidt, Lutz wrote:
> > > Dear all,
> > >
> > > may I please request reviews for this small change, fixing a regression in the disassembler. Parameters to the hsdis-<platform> library were not passed on.
> > >
> > > The change was verified to fix the issue by the reporter (Jean-Philippe Bempel, on CC:). jdk/submit tests pending...
> > >
> > > Bug: https://bugs.openjdk.java.net/browse/JDK-8234583
> > > Webrev: https://cr.openjdk.java.net/~lucy/webrevs/8234583.00/
> > >
> > > Thank you,
> > > Lutz
> > >
> >
> >
>
>
More information about the hotspot-compiler-dev
mailing list