[14] RFR(S): 8234583: PrintAssemblyOptions isn't passed to hsdis library

[Doerr, Martin]

Hi Lutz,

looks good to me, too. Thanks for fixing.

Best regards,
Martin


> -----Original Message-----
> From: hotspot-compiler-dev <hotspot-compiler-dev-
> bounces at openjdk.java.net> On Behalf Of Schmidt, Lutz
> Sent: Montag, 25. November 2019 21:48
> To: Vladimir Ivanov <vladimir.x.ivanov at oracle.com>; 'hotspot-compiler-
> dev at openjdk.java.net' <hotspot-compiler-dev at openjdk.java.net>
> Cc: Jean-Philippe BEMPEL <jean-philippe at bempel.fr>
> Subject: [CAUTION] Re: [14] RFR(S): 8234583: PrintAssemblyOptions isn't
> passed to hsdis library
> 
> 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> 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>
> 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> 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
>     >      >      >
>     >      >
>     >      >
>     >
>     >
>