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

[Vladimir Ivanov]

> 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
>      >      >
>      >
>      >
>      
>