RFR: 8290780: AArch64: Crash in c2 nmethod running RunThese30M.java [v2]

[Andrew Haley]

> Fix that masks the offsets used when adrp() is passed an unreachable destination. This reloc allows e.g. `adrp; movk; ldr` to access anywhere in the address space.
> 
> 
> #  SIGSEGV (0xb) at pc=0x0000ffff55964edc, pid=2843096, tid=2850366
> #
> # JRE version: Java(TM) SE Runtime Environment (20.0+7) (fastdebug build 20-ea+7-377)
> # Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 20-ea+7-377, compiled mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-aarch64)
> # Problematic frame:
> # J 91101 c2 java.io.ObjectOutputStream.enableReplaceObject(Z)Z java.base at 20-ea (47 bytes) @ 0x0000ffff55964edc [0x0000ffff55964e80+0x000000000000005c]

Andrew Haley has updated the pull request incrementally with one additional commit since the last revision:

  8290780: AArch64: Crash in c2 nmethod running RunThese30M.java

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9615/files
  - new: https://git.openjdk.org/jdk/pull/9615/files/db3866f8..f973e7a3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9615&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9615&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9615.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9615/head:pull/9615

PR: https://git.openjdk.org/jdk/pull/9615