[lworld] RFR: 8348606: [lworld] Substitutability test may perform heap allocations [v2]

[Chen Liang]

> Update substitutability test to use MethodHandles that access independent primitive/pointer instead heap reallocated copies of inlined values with an object header. Need long-term solution for user MethodHandle that accesses nested values in the future; hope the intrinsics can help in the future.
> 
> Testing: test/jdk/valhalla and test/hotspot/jtreg/*/valhalla, tier 1-3 tests running.

Chen Liang has updated the pull request incrementally with one additional commit since the last revision:

  Fix redundant debug and failing IO test

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Changes:
  - all: https://git.openjdk.org/valhalla/pull/1364/files
  - new: https://git.openjdk.org/valhalla/pull/1364/files/63c46847..4d6a7d5c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1364&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1364&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/1364.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1364/head:pull/1364

PR: https://git.openjdk.org/valhalla/pull/1364