RFR: 8357468: [asan] heap buffer overflow reported in PcDesc::pc_offset() pcDesc.hpp:57

[Dean Long]

This appears to be mostly harmless, but we should fix it anyway.  The initial sentinel PcDesc has a pc_offset of -1.  We can prevent looking before the sentinel by reversing the condition so that pc[0] is checked before pc[-1].

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Commit messages:
 - check pc[0] before pc[-1]

Changes: https://git.openjdk.org/jdk/pull/25404/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25404&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357468
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/25404.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25404/head:pull/25404

PR: https://git.openjdk.org/jdk/pull/25404