cpu: Simplify the rename interface and use RegId

With the hierarchical RegId there are a lot of functions that are
redundant now.

The idea behind the simplification is that instead of having the regId,
telling which kind of register read/write/rename/lookup/etc. and then
the function panic_if'ing if the regId is not of the appropriate type,
we provide an interface that decides what kind of register to read
depending on the register type of the given regId.

Change-Id: I7d52e9e21fc01205ae365d86921a4ceb67a57178
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
[ Fix RISCV build issues ]
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2702

arch, cpu: Architectural Register structural indexing

Replace the unified register mapping with a structure associating
a class and an index. It is now much easier to know which class of
register the index is referring to. Also, when adding a new class
there is no need to modify existing ones.

Change-Id: I55b3ac80763702aa2cd3ed2cbff0a75ef7620373
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
[ Fix RISCV build issues ]
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2700

X86: Consolidate extra microop flags into one parameter.

This single parameter replaces the collection of bools that set up various
flavors of microops. A flag parameter also allows other flags to be set like
the serialize before/after flags, etc., without having to change the
constructor.

copyright: Change HP copyright on x86 code to be more friendly

X86: Take limitted advantage of the compilers type checking for microop operands.

X86: Move the fp microops to their own file with their own base classes in C++ and python.

X86: Implemented and hooked in SCAS (scan string)
Fixed the asz assembler symbol.
Adjusted the condion checks to have appropriate options.
Implemented the SCAS microcode.
Attached SCAS into the decoder.

X86: Make disassembly use the final register index. Add bits to indicate whether or not register indexes should be "folded".

Fixed width parameter and provided a parameter to flip the carry bit on subtract.

Add in support for condition code flags.
Some microops can set the condition codes, and some of them can be predicated on them. Some of the codes aren't implemented because it was unclear from the AMD patent what they actually did. They are used with string instructions, but they use variables IP, DTF, and SSTF which don't appear to be documented.

Pull some hard coded base classes out of the isa description.