RFR: 8352140: UBSAN: fix the left shift of negative value in klass.hpp, array_layout_helper()

Mon Mar 24 09:57:47 UTC 2025

The `array_layout_helper()` with `jint tag` as its first arg, is called with a `tag` whose sign-bit is always set and considered as negative. This negative value is UB in left-shift operation.  Changing the type to `juint`  fixes this.

Tests:
linux-x64-debug tier1 with UBSAN enabled.

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

Commit messages:
 - 8352140: UBSAN: fix the left shift of negative value in klass.hpp, array_layout_helper()

Changes: https://git.openjdk.org/jdk/pull/24184/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24184&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8352140
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24184.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24184/head:pull/24184

PR: https://git.openjdk.org/jdk/pull/24184