RFR: 8375534: Debug method 'pp' should support compressed oops

[Tobias Hartmann]

The debug method `pp` is currently not able to handle compressed oops. This should fix it. The code is similar to `BlockLocationPrinter<CollectedHeapT>::print_location`.

**Before:**


(rr) call (void*) pp(0x6b9c08fc8)

"Executing pp"
java.lang.Runtime$Version 
{0x00000006b9c08fc8} - klass: 'java/lang/Runtime$Version' - flags: 

 - ---- fields (total size 4 words):
 - private final value 'version' 'Ljava/util/List;' @12  a 'java/util/ImmutableCollections$List12'{0x00000006b9c2cbb8} (0xd7385977)
 - private final value 'pre' 'Ljava/util/Optional;' @16  a 'java/util/Optional'{0x00000006b9c2cbd0} (0xd738597a)
 - private final value 'build' 'Ljava/util/Optional;' @20  a 'java/util/Optional'{0x00000006b9c0a118} (0xd7381423)
 - private final value 'optional' 'Ljava/util/Optional;' @24  a 'java/util/Optional'{0x00000006b9c2cbe8} (0xd738597d)
$1 = (void *) 0x0
(rr) call (void*) pp(0xd7381423)

"Executing pp"
The program being debugged received signal SIGSEGV, Segmentation fault
while in a function called from GDB.  GDB has restored the context
to what it was before the call.  To change this behavior use
"set unwind-on-signal off".  Evaluation of the expression containing
the function (pp(long)) will be abandoned.


**After:**
```(rr) call (void*) pp(0x6b9c08fc8)

"Executing pp"
java.lang.Runtime$Version 
{0x00000006b9c08fc8} - klass: 'java/lang/Runtime$Version' - flags: 

 - ---- fields (total size 4 words):
 - private final value 'version' 'Ljava/util/List;' @12  a 'java/util/ImmutableCollections$List12'{0x00000006b9c2cbb8} (0xd7385977)
 - private final value 'pre' 'Ljava/util/Optional;' @16  a 'java/util/Optional'{0x00000006b9c2cbd0} (0xd738597a)
 - private final value 'build' 'Ljava/util/Optional;' @20  a 'java/util/Optional'{0x00000006b9c0a118} (0xd7381423)
 - private final value 'optional' 'Ljava/util/Optional;' @24  a 'java/util/Optional'{0x00000006b9c2cbe8} (0xd738597d)
$1 = (void *) 0x0
(rr) call (void*) pp(0xd7381423)

"Executing pp"
3610776611 is a compressed pointer to object: java.util.Optional 
{0x00000006b9c0a118} - klass: 'java/util/Optional' - flags: 

 - ---- fields (total size 3 words):
 - private final value 'value' 'Ljava/lang/Object;' @16  null (0x00000000)
$2 = (void *) 0x0


Thanks,
Tobias

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

Commit messages:
 - JDK-8375534

Changes: https://git.openjdk.org/jdk/pull/29280/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29280&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8375534
  Stats: 14 lines in 1 file changed: 14 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/29280.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29280/head:pull/29280

PR: https://git.openjdk.org/jdk/pull/29280