RFR: 8263361: Incorrect arraycopy stub selected by C2 for SATB collectors

[Nils Eliasson]

This bug has only been reproduced with -XX:+StressReflectiveCode and -XX:-ReduceInitialCardMarks. If StressReflectiveCode is necessary isn't obvious.

I am fixing three things:

1) When running with ReduceInitialCardMarks enabled the stubroutines for int- or long-arraycopy will be used for arraycopies to tightly allocated arrays (like when cloning). With ReduceInitialCardMarks disabled the oop-version will be used with barriers.

The generate_arraycopy method in PhaseMacroExpand have a bool dest_uninitialized field - but that field denotes that we have proven that no zeroing is necessary (since all fields will be written anyway). 

To fix this bug generate_unchecked_arraycopy with the param dest_uninitialized will need to be appended with a check for tighly coupled object-copies when ReduceInitialCardMarks is disabled.

2) I also fix a bug in library_call kit where arraycopy for clones doesn't get marked as tightly coupled - The call to tightly_coupled_allocation can't be used when the IR isn't constructed yet.

3) In stubroutines.cpp I fix so that the name of the arraycopy stubroutines gets appended with _uninit when appropriate. This shows up in ir-dumps and IGV.

Please review,
Nils Eliasson

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Commit messages:
 - Fix acopy uninited

Changes: https://git.openjdk.java.net/jdk/pull/3008/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3008&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263361
  Stats: 8 lines in 3 files changed: 3 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3008.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3008/head:pull/3008

PR: https://git.openjdk.java.net/jdk/pull/3008