RFR(XXS) 8027751: C1 crashes in Weblogic with G1 enabled

[Igor Veresov]

G1 barriers use logical operators (xor) on T_OBJECT mixed with T_LONG or T_INT. The current implementation of logical operations on x86 in C1 doesn't allow for long operands to be on stack. There is a special code in the register allocator that forces long arguments in registers on x86. However T_OBJECT can be spilled just fine, and in that case the xor emission will fail.

The shortest fix is to force the allocator to keep operands of type T_OBJECT in registers when doing logical operations (as we do with T_LONG already) on 64bit x86.

Webrev: http://cr.openjdk.java.net/~iveresov/8027751/webrev.0/

Thanks!
igor