RFR: 8240302: x64: Assembler::reachable redundantly call Relocation::type() more than once

[Claes Redestad]

Hi,

in the x64-version Assembler::reachable method, various calls to
adr.reloc() are not hoisted by the compiler, due calling into the
virtual method Relocation::type(). This means each call to reachable
typically do several redundant calls into Relocation::type()

This patch refactors all these calls into a single one, which has a
small, but measurable, effect on startup (and likely some small
effect on JIT compiler throughput in general)

Webrev: http://cr.openjdk.java.net/~redestad/8240302/open.00/
Bug:    https://bugs.openjdk.java.net/browse/JDK-8240302

Testing: tier1-3

Thanks!

/Claes