RFR 8160197: [JVMCI] AllocatableValue.toString overrides are missing reference information

[Tom Rodriguez]

http://cr.openjdk.java.net/~never/8160197/webrev

When printing Values the current code restricts the information to a single character which cuts out any information about whether a type is a reference or not.  Instead Value should allow subclasses more control over what is printed for the type information.  In current graal this means instead of “rax|q” you’ll see “rax|QWORD[.]” for a reference type.  This also makes the platform dependent types more obvious since you don’t have to guess what “q” means.

tom