[jdk17u-dev] RFR: 8279545: Buffer overrun in reverse_words of sharedRuntime_x86_64.cpp:3517

[Aleksey Shipilev]

Clean backport to improve safety in Montgomery mult/square intrinsics from BigDecimal. The patch makes sure the `guarantee` fires when there is overflow. There is not impact on the actual code executing, when guarantee does not fire.

Additional testing:
 - [ ] GHA

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

Commit messages:
 - Backport 35734ad0805b9ecaf6eb72a4b1513b8de53ed72c

Changes: https://git.openjdk.org/jdk17u-dev/pull/1459/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1459&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8279545
  Stats: 21 lines in 3 files changed: 12 ins; 6 del; 3 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1459.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1459/head:pull/1459

PR: https://git.openjdk.org/jdk17u-dev/pull/1459