[jdk21u-dev] RFR: 8323101: C2: assert(n->in(0) == nullptr) failed: divisions with zero check should already have bailed out earlier in split-if [v2]

[Aleksey Shipilev]

> Clean backport to fix a C2 corner case.
> 
> Additional testing:
>  - [x] MacOS AArch64 server fastdebug: new tests fail without the patch, pass with the patch
>  - [x] Linux AArch64 server fastdebug, `tier{1,2,3,4}`

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into JDK-8323101-c2-div-splitif
 - Backport 7e0a4ed6292586772c23292dbdd67ed1db5c12f7

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

Changes:
  - all: https://git.openjdk.org/jdk21u-dev/pull/179/files
  - new: https://git.openjdk.org/jdk21u-dev/pull/179/files/c8eb23a8..4e643e86

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=179&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=179&range=00-01

  Stats: 11706 lines in 346 files changed: 7040 ins; 3383 del; 1283 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/179.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/179/head:pull/179

PR: https://git.openjdk.org/jdk21u-dev/pull/179