RFR: 8290291: G1: Merge multiple calls of block_size in HeapRegion::block_start

Thu Jul 14 09:05:31 UTC 2022

Simple change of merging duplicate inline calls. It reduces asm footprint, e.g. `G1RemSet::refine_card_concurrently` by ~200 bytes.

(The first commit is what I had originally -- inlining the block-walking logic, because block-walking logic is not used by others and highly specific to its sole caller. Ofc, this is subjective.)

Test: hotspot_gc

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Commit messages:
 - helper
 - g1-inline-forward-block

Changes: https://git.openjdk.org/jdk/pull/9490/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9490&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290291
  Stats: 47 lines in 2 files changed: 17 ins; 25 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/9490.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9490/head:pull/9490

PR: https://git.openjdk.org/jdk/pull/9490