RFR (S): 8227442: Make young_index_in_cset zero-based
Kim Barrett
kim.barrett at oracle.com
Sat Aug 17 04:48:55 UTC 2019
> On Aug 7, 2019, at 6:39 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
>
> Hi all,
>
> can I have reviews for this refactoring that changes the minimum index for the young indices (used for determining survivors per young region) from -1 to 0?
>
> This avoids some imho unnecessary increment in the copy_to_survivor_space() method.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8227442
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8227442/webrev/
> Testing:
> hs-tier1-5 almost done with no issues
>
> Thanks,
> Thomas
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src/hotspot/share/gc/g1/heapRegion.hpp
578 assert(_surv_rate_group != NULL, "pre-condition" );
and several others
If you are going to the bother of removing leading whitespace from
these asserts, why not also do the trailing whitespace?
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src/hotspot/share/gc/g1/heapRegion.hpp
572 assert(index != 0, "just checking");
573 assert((index == 0) || is_young(), "pre-condition" );
`index == 0` check on 573 is not useful with the preceeding check.
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src/hotspot/share/gc/g1/g1ParScanThreadState.cpp
In G1ParScanThreadState::copy_to_survivor_space:
[existing and retained, though modified for +1 removal]
225 HeapRegion* const from_region = _g1h->heap_region_containing(old);
226
227 const int young_index = from_region->young_index_in_cset();
[added later in the same function]
280 HeapRegion* const from_region = _g1h->heap_region_containing(old);
281 const uint young_index = from_region->young_index_in_cset();
I'm assuming the new addition was to put young_index closer to the
scope where it is actually used? I think the earlier declaration is
now unused except by the immediately following assert.
If it's important to have that assert up front, the associated
from_region and young_index ought to be debug-only too.
I'd prefer not having these nested declarations for the same variables.
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