[lworld] RFR: 8367518: TestRedundantLea.java fails in Valhalla [v2]

[Manuel Hässig]

> After merging `TestRedundantLea.java` into valhalla it turned out that the `StringInflate` and `StoreN*` subtests fail. This PR fixes that by bringing over two commits from mainline that fix problems with this test, which already fixes `StringInflate`.
> 
> The problem with the `StoreN` cases is that with valhalla C2 does not generate spills that the peephole can remove. To still test removing spills I came up with a new test case specifically for spills.
> 
> Testing:
>  - [x] tier1,tier2 plus some stress testing

Manuel Hässig has updated the pull request incrementally with one additional commit since the last revision:

  Apply suggestions from Christian
  
  Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/1605/files
  - new: https://git.openjdk.org/valhalla/pull/1605/files/6119e5e7..10670b68

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1605&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1605&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/valhalla/pull/1605.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1605/head:pull/1605

PR: https://git.openjdk.org/valhalla/pull/1605