[jdk16] RFR: 8256843: [PPC64] test RedefineClasses.java fails with assert: registers not saved on stack

[Richard Reingruber]

// Continuation of https://github.com/openjdk/jdk/pull/1724
// I'm taking over from @TheRealMDoerr who's busy with 11u downports

Please help review this small PPC64 fix.
It replaces the call os::current_stack_pointer() in os::current_frame()
with __builtin_frame_address(0) which is available also with xlC used by the AIX
build. With this os::current_frame() is agnostic to C++ compiler inlining.

Furthermore the fix changes os::current_frame() to return the correct
frame. Without the fix the returned frame is one frame to high which triggered
the assertion in trace_method_handle_stub().
This change uncovers an issue with NativeCallStack::NativeCallStack(int toSkip, bool fillStack)
on PPC64. There the call os::get_native_stack() is not compiled
to a tail call therefore the frame of the NativeCallStack constructor needs to
be skipped on PPC64 too as on other platforms.

Without this

make run-test TEST=test/hotspot/jtreg/runtime/NMT/CheckForProperDetailStackTrace.java

fails.

Furthermore the inline assembler from os::current_stack_pointer() is
removed. Instead __builtin_frame_address(0) is used again.

The fix passed our CI testing: JCK and JTREG, also in Xcomp mode, SPECjvm2008, SPECjbb2015, Renaissance Suite,
SAP specific tests with fastdebug and release builds on all platforms

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Commit messages:
 - 8256843: [PPC64] test RedefineClasses.java fails with assert: registers not saved on stack

Changes: https://git.openjdk.java.net/jdk16/pull/24/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk16&pr=24&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256843
  Stats: 31 lines in 3 files changed: 0 ins; 22 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk16/pull/24.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16 pull/24/head:pull/24

PR: https://git.openjdk.java.net/jdk16/pull/24