RFR(S): 8185334: [MVT] nmethod::print_nmethod_labels() does not work with -XX:+ValueTypePassFieldsAsArgs

[Tobias Hartmann]

Hi,

please review the following patch:
https://bugs.openjdk.java.net/browse/JDK-8185334
http://cr.openjdk.java.net/~thartmann/valhalla/vt_prototype/webrev.32/

If -XX:+ValueTypePassFieldsAsArgs is enabled, the compiled method parameters in the -XX:CompileCommand=print output should be adjusted to point to the actual fields being passed. The current output looks like this:

  # {method} {0x00007fb6d1dafe60} 'test35' '(JQcompiler/valhalla/valuetypes/MyValue1;IQcompiler/valhalla/valuetypes/MyValue2;)J' in 'compiler/valhalla/valuetypes/ValueTypeTestBench'
  # this:     rsi:rsi   = 'compiler/valhalla/valuetypes/ValueTypeTestBench'
  # parm0:    rdx:rdx   = long
  # parm1:    rcx:rcx   = 'compiler/valhalla/valuetypes/MyValue1'
  # parm2:    r8        = int
  # parm3:    r9:r9     = 'compiler/valhalla/valuetypes/MyValue2'

With the patch it looks like this:

  # {method} {0x00007fdb5089ce60} 'test35' '(JQcompiler/valhalla/valuetypes/MyValue1;IQcompiler/valhalla/valuetypes/MyValue2;)J' in 'compiler/valhalla/valuetypes/ValueTypeTestBench'
  # parm0:    rsi:rsi   = 'java/lang/Object'
  # parm1:    rdx:rdx   = long
  # parm2:    rcx:rcx   = long
  # parm3:    r8        = int
  # parm4:    r9        = int
  # parm5:    rdi       = short
  # parm6:    [sp+0xa0]   = 'java/lang/Object'  (sp of caller)
  # parm7:    [sp+0xa8]   = array
  # parm8:    [sp+0xb0]   = long
  # parm9:    [sp+0xb8]   = int
  # parm10:   [sp+0xc0]   = byte
  # parm11:   [sp+0xc8]   = boolean
  # parm12:   [sp+0xd0]   = long
  # parm13:   [sp+0xd8]   = int
  # parm14:   [sp+0xe0]   = byte
  # parm15:   [sp+0xe8]   = boolean
  # parm16:   [sp+0xf0]   = int
  # parm17:   [sp+0xf8]   = long
  # parm18:   [sp+0x100]   = int
  # parm19:   [sp+0x108]   = byte
[...]

This patch includes some other cleanups:
- sharedRuntime_x86_64.cpp: We should not use VOID as placeholder because this confuses other signature printing code
- compiledMethod.cpp: We can safely assume that the method has a value type argument if an extended signature is available. I moved the verification code into #ifdef ASSERT.
- signature.cpp: 
-> If the type is 'L;' (no Klass information) we currently print
   # parm0:    rsi:rsi   = ''
   With the changes we print:
   # parm0:    rsi:rsi   = 'java/lang/Object'

Thanks,
Tobias