[lworld] RFR: 8376733: [lworld] Inconsistent result of Invoke::declared_type triggers assert in profiling

[Tobias Hartmann]

Old mainline fix [JDK-8134389](https://bugs.openjdk.org/browse/JDK-8134389) modified code in `Invoke::declared_type` to not use the return type of the target signature but use the declared signature instead (see [changeset](https://hg.openjdk.org/jdk9/jdk9/hotspot/rev/4191b33b3629) for details). This was needed for method handle call sites to return `java/lang/invoke/CallSite` instead of `java/lang/Object` or whatever the target method return type would look like. The test `compiler/jsr292/TestArrayReturnType.java` still reliably triggers this scenario.

Now the problem is that the return type is re-computed on every call to `Invoke::declared_type` but it might actually change from unloaded to loaded in-between and therefore different `ciType` objects will be returned. In the failing case, the return type first is
`<ciObjArrayKlass name=[Ljava/lang/reflect/Field; loaded=false ident=1498 address=0x00007ae57d775728>` 
and later it's `<ciObjArrayKlass name=[Ljava/lang/reflect/Field; loaded=true ident=1508 address=0x00007ae57d7762a8>` (note the different `loaded` property). This leads to an assertion failure in profiling because we invoke CHA to improve a type that's already final because when we checked the type earlier, it was still unloaded.

I think it's a general rule that the compiler interface needs to guarantee consistency of types during compilation and therefore I adjusted the code to only compute the return type once. This is a mainline issue and could be fixed in mainline as well. However, as far as I can tell, only Valhalla is currently affected because the Valhalla specific array load/store profiling uses `LIRGenerator::profile_type` in more cases. Let's therefore only fix it in Valhalla for now.

Thanks,
Tobias

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Commit messages:
 - 8376733: [lworld] Inconsistent result of Invoke::declared_type triggers assert in profiling

Changes: https://git.openjdk.org/valhalla/pull/2031/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2031&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376733
  Stats: 17 lines in 3 files changed: 3 ins; 2 del; 12 mod
  Patch: https://git.openjdk.org/valhalla/pull/2031.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2031/head:pull/2031

PR: https://git.openjdk.org/valhalla/pull/2031