RFR [S]: 8079473: allow demangling to be optional in dll_address_to_function_name

[Bertrand Delsart]

Hi all,

Here is a webrev that add a 'demangle' argument to 
dll_address_to_function_name so as to make the demangling optional. The 
webrev also includes some limited cleanup and fixes an issue I noticed 
on windows.

https://bugs.openjdk.java.net/browse/JDK-8079473
http://cr.openjdk.java.net/~bdelsart/8079473/

Fix is targeted at JDK9 and will be pushed through hs-rt.

This enhancement is currently used only by some closed extensions. It 
has been validated on linux and the fix is very similar on all platforms 
except AIX.

I've quickly implemented the AIX version but could not test it. Let me 
know if you would prefer me to remove the AIX code and just ensure that 
the 'demangle' argument is ignored on that platform.

The cleanup is about optional arguments to decode, which were redefined 
in the overridden versions for the different operating systems. To avoid 
weird behaviors, the default values should be defined only in the 
toplevel class AbstractDecoder, not the subclasses (but that was OK as 
long as the default values were identical)

On Windows, I discovered a bug while adding the non-demangling support.
This old code from WindowsDecoder::decode should not behave as expected 
if really used:
         if (demangle(pSymbol->Name, buf, buflen)) {
           jio_snprintf(buf, buflen, "%s", pSymbol->Name);
         }
The code is supposed to write in 'buf' the raw form when the demangling 
fails. Hence, the jio_snprintf should be executed when demangle returns 
false. The code above fails to properly set buf when the demangling 
fails and also replaced the demangled form by the raw form when 
demangling succeeded.

It should have been "if (! demangle(...". With my extension, it now is 
"if (!(demangle_name && demangle(...", like on other platforms.

Best regards,

Bertrand.
-- 
Bertrand Delsart,                     Grenoble Engineering Center
Oracle,         180 av. de l'Europe,          ZIRST de Montbonnot
38330 Montbonnot Saint Martin,                             FRANCE
bertrand.delsart at oracle.com             Phone : +33 4 76 18 81 23

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