RFR: JDK-8157141 & JDK-8166454: Solaris getisax(2) and meminfo(2) cleanup

[Kim Barrett]

> On Sep 27, 2016, at 9:47 AM, Alan Burlison <Alan.Burlison at oracle.com> wrote:
> 
> On 27/09/2016 00:54, David Holmes wrote:
> 
>> Thanks Alan. It is the creation of the intermediate log-stream that can
>> not be accomplished at this stage of VM initialization so we will need
>> to stick with what you had. Thanks for trying.
> 
> Done. I've tweaked the output slightly, it is now:
> 
> torside-kz6$ ./java -Xlog:os+cpu -version
> [0.177s][info][os,cpu] getisax(2) returned 1 words:
> [0.177s][info][os,cpu]     word 1: 0x3ffe8df0
> 
> That's on a M5, on a T7 and similar it will be 2 words. I've respun the webrev, for reference here are the review links again:
> 
> getisainfo() manpage:
> http://docs.oracle.com/cd/E53394_01/html/E54765/getisax-2.html
> 
> meminfo() manpage:
> https://docs.oracle.com/cd/E53394_01/html/E54765/meminfo-2.html
> 
> Bugs:   https://bugs.openjdk.java.net/browse/JDK-8157141
>        https://bugs.openjdk.java.net/browse/JDK-8166454
> Webrev: http://cr.openjdk.java.net/~alanbur/JDK-8157141%2bJDK-8166454/

------------------------------------------------------------------------------ 
src/os_cpu/solaris_sparc/vm/vm_version_solaris_sparc.cpp 
 377   uint_t av1 = avs[AV_HW1_IDX];
 378   if (av1 & AV_SPARC_MUL32)        features |= hardware_mul32_m;
...

Good to use the symbolic index AV_HW1_IDX. Bad form to assume we have
that many entries.  That should be

  if (avn > AV_HW1_IDX) {
    uint_t av1 = avs[AV_HW1_IDX];
    if (av1 & AV_SPARC_MUL32)        features |= hardware_mul32_m;
    ...
  }

------------------------------------------------------------------------------ 
src/os_cpu/solaris_sparc/vm/vm_version_solaris_sparc.cpp 
 368   uint_t avn = getisax(NULL, 0);
 369   uint_t *avs = (uint_t*) alloca(avn * sizeof(uint_t));
 370   (void) getisax(avs, avn);

I still think the use of alloca here is overkill, along with depending
on (currently) undocumented behavior of getisax, but this is called
once initialization code and you've filed the doc bug, so okay.

------------------------------------------------------------------------------

I don't need a new webrev for the insertion of the avn check.

> A JPRT hotspot testset run is clean.

Have you used logging to hand-verify the expected features are being set?