RFR: 8267213: assert(left >= right) failed: avoid underflow

[Jie Fu]

Hi all,

This is a follow-up of JDK-8260046.
And it can be reproduced by `java -XX:UnguardOnExecutionViolation=1` on x86_32.
Let's fix it

Thanks.
Best regards,
Jie

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Commit messages:
 - 8267213: assert(left >= right) failed: avoid underflow

Changes: https://git.openjdk.java.net/jdk/pull/4044/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4044&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267213
  Stats: 21 lines in 3 files changed: 15 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4044.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4044/head:pull/4044

PR: https://git.openjdk.java.net/jdk/pull/4044