arm: Stop using the FloatReg and FloatRegBits types.

This will let us make those types 64 bits to be in line with the other
architectures.

Change-Id: I5aef5199f4d2d5bb1558afedac5c6c92bf95c021
Reviewed-on: https://gem5-review.googlesource.com/c/13621
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

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

style: [patch 1/22] use /r/3648/ to reorganize includes

style: fix missing spaces in control statements

Result of running 'hg m5style --skip-all --fix-control -a'.

arm: always set the IsFirstMicroop flag

While the IsFirstMicroop flag exists it was only occasionally used in the ARM
instructions that gem5 microOps and therefore couldn't be relied on to be correct.

arm: Fixes based on UBSan and static analysis

Another churn to clean up undefined behaviour, mostly ARM, but some
parts also touching the generic part of the code base.

Most of the fixes are simply ensuring that proper intialisation. One
of the more subtle changes is the return type of the sign-extension,
which is changed to uint64_t. This is to avoid shifting negative
values (undefined behaviour) in the ISA code.

arm: Make memory ops work on 64bit/128-bit quantities

Multiple instructions assume only 32-bit load operations are available,
this patch increases load sizes to 64-bit or 128-bit for many load pair and
load multiple instructions.

arm: Fix v8 neon latency issue for loads/stores

Neon memory ops that operate on multiple registers currently have very poor
performance because of interleave/deinterleave micro-ops.

This patch marks the deinterleave/interleave micro-ops as "No_OpClass" such
that they take minumum cycles to execute and are never resource constrained.

Additionaly the micro-ops over-read registers. Although one form may need
to read up to 20 sources, not all do. This adds in new forms so false
dependencies are not modeled. Instructions read their minimum number of
sources.

arm: Add branch flags onto macroops

Mark branch flags onto macroops to allow branch prediction before
microop decomposition

arm: Correctly display disassembly of vldmia/vstmia

The MicroMemOp class generates the disassembly for both integer
and floating point instructions, but it would always print its
first operand as an integer register without considering that the
op may be a floating instruction in which case a float register
should be displayed instead.

arm: Add support for ARMv8 (AArch64 & AArch32)

Note: AArch64 and AArch32 interworking is not supported. If you use an AArch64
kernel you are restricted to AArch64 user-mode binaries. This will be addressed
in a later patch.

Note: Virtualization is only supported in AArch32 mode. This will also be fixed
in a later patch.

Contributors:
Giacomo Gabrielli (TrustZone, LPAE, system-level AArch64, AArch64 NEON, validation)
Thomas Grocutt (AArch32 Virtualization, AArch64 FP, validation)
Mbou Eyole (AArch64 NEON, validation)
Ali Saidi (AArch64 Linux support, code integration, validation)
Edmund Grimley-Evans (AArch64 FP)
William Wang (AArch64 Linux support)
Rene De Jong (AArch64 Linux support, performance opt.)
Matt Horsnell (AArch64 MP, validation)
Matt Evans (device models, code integration, validation)
Chris Adeniyi-Jones (AArch64 syscall-emulation)
Prakash Ramrakhyani (validation)
Dam Sunwoo (validation)
Chander Sudanthi (validation)
Stephan Diestelhorst (validation)
Andreas Hansson (code integration, performance opt.)
Eric Van Hensbergen (performance opt.)
Gabe Black

arm: set ldr_ret_uop as conditional or unconditional control
This patch adds a missing flag to the ldr_ret_uop microop instruction.
The flag is added when the instruction is used, not directly in the
constructor of the instruction.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>"

arm: set movret_uop as conditional or unconditional control
A flag was missing for the movret_uop microop instruction. This patch adds
that flag when the instruction is used, not directly in the constructor of
the instruction.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>

ARM: Predict target of more instructions that modify PC.

ISA: Put parser generated files in a "generated" directory.

This is to avoid collision with non-generated files.

StaticInst: Merge StaticInst and StaticInstBase.

Having two StaticInst classes, one nominally ISA dependent and the other ISA
dependent, has not been historically useful and makes the StaticInst class
more complicated that it needs to be. This change merges StaticInstBase into
StaticInst.

includes: sort all includes

ARM: Remove debugging warn that was accidently left in.

ARM: Fix subtle bug in LDM.

If the instruction faults mid-op the base register shouldn't be written back.

ARM: Fix RFE macrop.

This changes the RFE macroop into 3 microops:

URa = [sp]; URb = [sp+4]; // load CPSR,PC values from stack
sp = sp + offset; // optionally auto-increment
PC = URa; CPSR = URb; // write to the PC and CPSR.

Importantly:
- writing to PC is handled in the last micro-op.
- loading occurs prior to state changes.

ARM: The ARM decoder should not panic when decoding undefined holes is arch.

This can abort simulations when the fetch unit runs ahead and speculatively
decodes instructions that are off the execution path.

ARM: Use fewer micro-ops for register update loads if possible.

Allow some loads that update the base register to use just two micro-ops. three
micro-ops are only used if the destination register matches the offset register
or the PC is the destination regsiter. If the PC is updated it needs to be
the last micro-op otherwise O3 will mispredict.

ARM: Implement all ARM SIMD instructions.

ARM: Improve printing of uop disassembly.

ARM: Fix double precision load/store multiple decrement.

When decrementing, the higher addressed half of a double word is at a 4 byte
smaller displacement.

ARM: Make sure macroops aren't interrupted midinstruction.

Do this by setting the delayed commit flag for all but the last microop.

ARM: Fix the implementation of the VFP ldm and stm macroops.

There were four bugs in these instructions. First, the loaded value was being
stored into a floating point register as floating point, changing the value as
it was transfered. Second, the meaning of the "up" bit had been reversed.
Third, the statically sized microop array wasn't bit enough for all possible
inputs. It's now dynamically sized and should always be big enough. Fourth,
the offset was stored as an unsigned 8 bit value. Negative offsets would look
like moderately large positive offsets.

ARM: Allow flattening into any mode.

ARM: Make sure ldm exception return writes back its base in the right mode.

This change moves the writeback of load multiple instructions to the beginning
of the macroop. That way, the MicroLdrRetUop that changes the mode will
necessarily happen later, ensuring the writeback happens in the original mode.
The actual value in the base register if it also shows up in the register list
is undefined, so it's fine if it gets clobbered by one of the loads. For
stores where the base register is the lowest numbered in the register list,
the original value should be written back. That means stores can't write back
at the beginning, but the mode changing problem doesn't affect them so they
can continue to write back at the end.

ARM: Add base classes for VFP load/store multiple.

ARM: Move the macro mem constructor out of the isa desc.
This code doesn't use the parser at all, and moving it out reduces the
conceptual complexity of that code.