RFR: 8230797: ARM32-softfp: assertion in InterpreterRuntime::resolve_ldc [v2]

[Christoph Göttschkes]

> Hi,
> 
> please review the following change, which was way too long on my chest. It fixes an assertion in the template interpreter for ARM32-softfp.
> 
> For ARM32-softfp, the template interpreter calls into the runtime to load a double constant using the ldc bytecode. After the interpreter loaded the constants, the assert block does some sanity checks on the cached constants. But if the double constant is the first constant to be loaded, the cache is not yet initialized and the check results in a SIGSEGV.
> 
> I guarded the usage of `ConstantPool::cp_to_object_index` by another check, which tests if there are any resolved references and if that's the case, the cache has already been initialized and the sanity checks can be performed.

Christoph Göttschkes has updated the pull request incrementally with one additional commit since the last revision:

  Adds an additional NULL check for the CP _cache.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4582/files
  - new: https://git.openjdk.java.net/jdk/pull/4582/files/8d0d5ea3..667966f3

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4582&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4582&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4582.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4582/head:pull/4582

PR: https://git.openjdk.java.net/jdk/pull/4582