RFR 8014911 - Use SUPPORTS_NATIVE_CX8 to help C++ compiler elide code
BILL PITTORE
bill.pittore at oracle.com
Wed Sep 18 09:39:18 PDT 2013
Would like a review for this simple fix that leverages the macro
'SUPPORTS_NATIVE_CX8' that was added in hotspot revision:
changeset: 4611:6b388e7d4905
parent: 4547:e01e02a9fcb6
user: bpittore
date: Tue May 07 10:19:33 2013 -0400
summary: 8013633: Cleanup platform ifdefs in unsafe.cpp
SUPPORTS_NATIVE_CX8 is defined in globalDefinitions_<arch>.hpp based on
whether the platform supports 64bit cmpxchg natively. This change uses
the define to force the supports_cx8() function to return hard-coded
'true' value. GCC and other compilers will then optimize code that uses
supports_cx8() function call by removing the actual reference to
_supports_cx8 variable as well as eliminating code for the
!supports_cx8() case.
Webrev is here: http://cr.openjdk.java.net/~bpittore/8014911/webrev.00/
thanks,
bill
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