arch-arm: Added LD/ST<op> atomic instruction family and SWP instrs

Adding LD/ST/SWP family of instructions, LD/ST include a set of
operations like ADD/CLR/EOR/SET/UMAX/UMIN/SMAX/SMIN
This commit includes:
+ Instruction decode
+ Instruction functional code
+ New set of skeletons for Ex/Com/Ini/Constructor and declaration.

Change-Id: Ieea8d4256807e004d2f8aca8f421b3df8d76b116
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19812
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

arch-arm: Adding CAS/CASP AMO instr including new TypedAtomic func

CAS/CASP atomic instruction implementation
This change includes:
+ Instructions decode
+ new amo64.isa file where CAS/CASP main functional code is implemented
+ mem64.isa include Execute/complete/initiatie skeletons,
contructor and declarator
+ Added TypedAtomic function for pair register CASP instruction

Change-Id: I4a4acdec4ab1c8b888f10ef5dc1e896be8c432bf
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19811
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

arch-arm: Rewrite MSR immediate instruction class

MSR <pstatefield>, #imm is used for setting a PSTATE field using an
immediate. Current implementation has the following flaws:

* There is no base MSR immediate definition: all the existing
PSTATE fields have a different class definition
* Those implementation make use of a generic data64 base class
which results in a wrong disassembly (pstate register is printed as an
integer register).

This patch is fixing this by defining a new base class (MiscRegImmOp64)
and new related templates. In this way, we aim to ease addition of new
PSTATE fields (in ARMv8.x)

Change-Id: I71b630ff32abe1b105bbb3ab5781c6589b67d419
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19728
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Fix tracing code for SVE gather

Printing the entire contents of the dest vecreg for each gather
microop is suboptimal as it creates false positive differences
between Atomic and O3 traces. This fix prints only the memory
data which a microop loads from memory.

Change-Id: Idd8e0b26a96f9c9cc0b69360174bedf6a9f6dcb5
Signed-off-by: Gabor Dozsa <gabor.dozsa@arm.com>
Reviewed-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19171
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Add support for SVE load/store structures

Change-Id: I4d9cde18dfc3d478eacc156de6a4a9721eb9e2ff
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/13524
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Add first-/non-faulting load instructions

First-/non-faulting loads are part of Arm SVE.

Change-Id: I93dfd6d1d74791653927e99098ddb651150a8ef7
Signed-off-by: Gabor Dozsa <gabor.dozsa@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19177
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Move the memacc_code before op_wb in fp loads

This is trying to fix the bug that arises when a memory exception
is generated during a fp flavoured load (A memory load targeting
a SIMD & FP register).
With the previous template a fault was not stopping the register
value to be modified (wrong)

if (fault == NoFault) {
fault = readMemAtomic(xc, traceData, EA, Mem, memAccessFlags);
%(memacc_code)s;
}

if (fault == NoFault) {
%(op_wb)s;
}

The patch introduces a Load64FpExecute template which is moving the
register write (memacc_code) just before the op_wb

Change-Id: I1c89c525dfa7a4ef489abe0872cd7baacdd6ce3c
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19228
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Add initial support for SVE gather/scatter loads/stores

Change-Id: I891623015b47a39f61ed616f8896f32a7134c8e2
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/13521
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

arch-arm: Add initial support for SVE contiguous loads/stores

Thanks to Pau Cabre and Adria Armejach Sanosa for their contribution
of bugfixes.

Change-Id: If8983cf85d95cddb187c90967a94ddfe2414bc46
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/13519
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

arch-arm,cpu: Add initial support for Arm SVE

This changeset adds initial support for the Arm Scalable Vector Extension
(SVE) by implementing:
- support for most data-processing instructions (no loads/stores yet);
- basic system-level support.

Additional authors:
- Javier Setoain <javier.setoain@arm.com>
- Gabor Dozsa <gabor.dozsa@arm.com>
- Giacomo Travaglini <giacomo.travaglini@arm.com>

Thanks to Pau Cabre for his contribution of bugfixes.

Change-Id: I1808b5ff55b401777eeb9b99c9a1129e0d527709
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/13515
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

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-arm: AArch32 Crypto SHA

This patch implements the AArch32 secure hashing instructions
from the Crypto extension.

Change-Id: Iaba8424ab71800228a9aff039d93f5c35ee7d8e5
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13247
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch: Fix all override related warnings.

Clang has started(?) reporting override related warnings, something gcc
apparently did before, but was disabled in the SConstruct. Rather than
disable the warnings in for clang as well, this change fixes the
warnings. A future change will re-enable the warnings for gcc.

Change-Id: I3cc79e45749b2ae0f9bebb1acadc56a3d3a942da
Reviewed-on: https://gem5-review.googlesource.com/9343
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

arch-arm: Adding isa templates for semihosting ops

A new class of Semihosting constructor templates has been added. Their
main purpose is to check if the Exception Generation Instructions (HLT,
SVC) are actually a semihosting command. If that is the case, the
IsMemBarrier flag is raised, so that in the O3 model we perform a
coherent memory access during the semihosting operation.

Change-Id: Ib87fdeb70ee7a930659563230a80cce0e1372c32
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8370
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Fix Hlt64,Svc64,Hvc64,Smc64,Brk64 disassembly

This patch fixes the disassembly of AArch64 Exception Generating
instructions, which were not printing the encoded immediate field. This
has been accomplished by changing their underlying type to a newly
defined one.

Change-Id: If58ae3e620d2baa260e12ecdc850225adfcf1ee5
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8368
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch-arm: Fix cache line size for cache maintenace inst

Cache maintenance operations operate on whole cache blocks. This
changeset uses the system cache line size as the size of the cache
maintenance requests and masks the lower bits of the effective
address.

Change-Id: I6e7aefff51670c8cac39e4e73db21a0c5a0b7aef
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/7824
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arm: Add support for the dc {civac, cvac, cvau, ivac} instr

This patch adds support for decoding and executing the following ARMv8
cache maintenance instructions by Virtual Address:
* dc civac: Clean and Invalidate by Virtual Address to the Point
of Coherency
* dc cvac: Clean by Virtual Address to the Point of Coherency
* dc cvau: Clean by Virtual Address to the Point of Unification
* dc ivac: Invalidate by Virtual Addrsess to the Point of Coherency

Change-Id: I58cabda37f9636105fda1b1e84a0a04965fb5670
Reviewed-by: Sudhanshu Jha <sudhanshu.jha@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5060
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: Add support for the mcr dc{ic,i,c}mvac, dccmvau instructions

This patch adds support for the ARMv7 cache maintenance
intructions:
* mcr dccmvac cleans a VA to the PoC
* mcr dcimvac invalidates a VA to the PoC
* mcr dccimvac cleans and invalidates a VA to the PoC
* mcr dccmvau cleans a VA to the PoU

Change-Id: I6511f203039ca145cc9128ddf61d09d6d7e40c10
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
Reviewed-by: Anouk Van Laer <anouk.vanlaer@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5059
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

arch-arm: Fix MSR/MRS disassemble

This patch is fixing the Aarch64 MSR/MRS disassemble, which was
previously printing unexisting integer registers as source/destination
operands rather than the system register name

Change-Id: Iac9d5f2f2fea85abd9a398320ef7aa4844d43c0e
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5861
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

alpha,arm,mips,power,riscv,sparc,x86: Merge exec decl templates.

In the ISA instruction definitions, some classes were declared with
execute, etc., functions outside of the main template because they
had CPU specific signatures and would need to be duplicated with
each CPU plugged into them. Now that the instructions always just
use an ExecContext, there's no reason for those templates to be
separate. This change folds those templates together.

Change-Id: I13bda247d3d1cc07c0ea06968e48aa5b4aace7fa
Reviewed-on: https://gem5-review.googlesource.com/5401
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Alec Roelke <ar4jc@virginia.edu>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

alpha,arm,mips,power,riscv,sparc,x86,isa: De-specialize ExecContexts.

The ISA parser used to generate different copies of exec functions
for each exec context class a particular CPU wanted to use. That's
since been changed so that those functions take a pointer to the base
ExecContext, so the code which would generate those extra functions
can be removed, and some functions which used to be templated on an
ExecContext subclass can be untemplated, or minimally less templated.

Now that some functions aren't going to be instantiated multiple times
with different signatures, there are also opportunities to collapse
templates and make many instruction definitions simpler within the
parser. Since those changes will be less mechanical, they're left for
later changes and will probably be done in smaller increments.

Change-Id: I0015307bb02dfb9c60380b56d2a820f12169ebea
Reviewed-on: https://gem5-review.googlesource.com/5381
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arch: ISA parser additions of vector registers

Reiley's update :) of the isa parser definitions. My addition of the
vector element operand concept for the ISA parser. Nathanael's modification
creating a hierarchy between vector registers and its constituencies to the
isa parser.

Some fixes/updates on top to consider instructions as vectors instead of
floating when they use the VectorRF. Some counters added to all the
models to keep faithful counts.

Change-Id: Id8f162a525240dfd7ba884c5a4d9fa69f4050101
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2706
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

isa,arm: Add missing AArch32 FP instructions

This commit adds missing non-predicated, scalar floating point
instructions. Specifically VRINT* floating point integer rounding
instructions and VSEL* floating point conditional selects.

Change-Id: I23cbd1389f151389ac8beb28a7d18d5f93d000e7
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nathanael Premillieu <nathanael.premillieu@arm.com>

arm: Correctly check FP/SIMD access permission in aarch32

The current implementation of aarch32 FP/SIMD in gem5 assumes that EL1
and higher are all 32-bit. This breaks interprocessing since an
aarch64 EL1 uses different enable/disable bits. This change updates
the permission checks to according to what is prescribed by the ARM
ARM.

Change-Id: Icdcef31b00644cfeebec00216b3993aa1de12b88
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Mitch Hayenga <mitch.hayenga@arm.com>
Reviewed-by: Nathanael Premillieu <nathanael.premillieu@arm.com>

arm: Fix heap overflow issue in Neon64Load operation

This patch fixes an issue identified by ASAN where the Neon64Load
operation assumes the packet always contains 16 bytes.

Change-Id: If24a7e461d60cb80970dfbe61d923d7d56926698
Reviewed-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>

cpu. arch: add initiateMemRead() to ExecContext interface

For historical reasons, the ExecContext interface had a single
function, readMem(), that did two different things depending on
whether the ExecContext supported atomic memory mode (i.e.,
AtomicSimpleCPU) or timing memory mode (all the other models).
In the former case, it actually performed a memory read; in the
latter case, it merely initiated a read access, and the read
completion did not happen until later when a response packet
arrived from the memory system.

This led to some confusing things, including timing accesses
being required to provide a pointer for the return data even
though that pointer was only used in atomic mode.

This patch splits this interface, adding a new initiateMemRead()
function to the ExecContext interface to replace the timing-mode
use of readMem().

For consistency and clarity, the readMemTiming() helper function
in the ISA definitions is renamed to initiateMemRead() as well.
For x86, where the access size is passed in explicitly, we can
also get rid of the data parameter at this level. For other ISAs,
where the access size is determined from the type of the data
parameter, we have to keep the parameter for that purpose.

arm: Remove unnecessary dependencies between AArch64 FP instructions

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.

arch: Use shared_ptr for all Faults

This patch takes quite a large step in transitioning from the ad-hoc
RefCountingPtr to the c++11 shared_ptr by adopting its use for all
Faults. There are no changes in behaviour, and the code modifications
are mostly just replacing "new" with "make_shared".

arm: More UBSan cleanups after additional full-system runs

Some incorrect casting to IntRegIndex, and a few uninitialized members
in the i8254xGBe device.

arm: Fixed undefined behaviours identified by gcc

This patch fixes the runtime errors highlighted by the undefined
behaviour sanitizer. In the end there were two issues. First, when
rotating an immediate, we ended up shifting an uint32_t by 32 in some
cases. This case is fixed by checking for a rotation by 0
positions. Second, the Mrc15 and Mcr15 are operating on an IntReg and
a MiscReg, but we used the type RegRegImmOp and passed a MiscRegIndex
as an IntRegIndex. This issue is resolved by introducing a
MiscRegRegImmOp and RegMiscRegImmOp with the appropriate types.

With these fixes there are no runtime errors identified for the full
ARM regressions.

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: Mark v7 cbz instructions as direct branches

v7 cbz/cbnz instructions were improperly marked as indirect branches.

arm: Make sure UndefinedInstructions are properly initialized

arm: Add branch flags onto macroops

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

arch: teach ISA parser how to split code across files

This patch encompasses several interrelated and interdependent changes
to the ISA generation step. The end goal is to reduce the size of the
generated compilation units for instruction execution and decoding so
that batch compilation can proceed with all CPUs active without
exhausting physical memory.

The ISA parser (src/arch/isa_parser.py) has been improved so that it can
accept 'split [output_type];' directives at the top level of the grammar
and 'split(output_type)' python calls within 'exec {{ ... }}' blocks.
This has the effect of "splitting" the files into smaller compilation
units. I use air-quotes around "splitting" because the files themselves
are not split, but preprocessing directives are inserted to have the same
effect.

Architecturally, the ISA parser has had some changes in how it works.
In general, it emits code sooner. It doesn't generate per-CPU files,
and instead defers to the C preprocessor to create the duplicate copies
for each CPU type. Likewise there are more files emitted and the C
preprocessor does more substitution that used to be done by the ISA parser.

Finally, the build system (SCons) needs to be able to cope with a
dynamic list of source files coming out of the ISA parser. The changes
to the SCons{cript,truct} files support this. In broad strokes, the
targets requested on the command line are hidden from SCons until all
the build dependencies are determined, otherwise it would try, realize
it can't reach the goal, and terminate in failure. Since build steps
(i.e. running the ISA parser) must be taken to determine the file list,
several new build stages have been inserted at the very start of the
build. First, the build dependencies from the ISA parser will be emitted
to arch/$ISA/generated/inc.d, which is then read by a new SCons builder
to finalize the dependencies. (Once inc.d exists, the ISA parser will not
need to be run to complete this step.) Once the dependencies are known,
the 'Environments' are made by the makeEnv() function. This function used
to be called before the build began but now happens during the build.
It is easy to see that this step is quite slow; this is a known issue
and it's important to realize that it was already slow, but there was
no obvious cause to attribute it to since nothing was displayed to the
terminal. Since new steps that used to be performed serially are now in a
potentially-parallel build phase, the pathname handling in the SCons scripts
has been tightened up to deal with chdir() race conditions. In general,
pathnames are computed earlier and more likely to be stored, passed around,
and processed as absolute paths rather than relative paths. In the end,
some of these issues had to be fixed by inserting serializing dependencies
in the build.

Minor note:
For the null ISA, we just provide a dummy inc.d so SCons is never
compelled to try to generate it. While it seems slightly wrong to have
anything in src/arch/*/generated (i.e. a non-generated 'generated' file),
it's by far the simplest solution.

arch: remove inline specifiers on all inst constrs, all ISAs

With (upcoming) separate compilation, they are useless. Only
link-time optimization could re-inline them, but ideally
feedback-directed optimization would choose to do so only for
profitable (i.e. common) instructions.

arm: cleanup ARM ISA definition

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: fix some cases where instructions that write to fp reg 15 are accidently branches.

scons: Add warning for overloaded virtual functions

A derived function with a different signature than a base class
function will result in the base class function of the same name being
hidden. The parameter list and return type for the member function in
the derived class must match those of the member function in the base
class, otherwise the function in the derived class will hide the
function in the base class and no polymorphic behaviour will occur.

This patch addresses these warnings by ensuring a unique function name
to avoid (unintentionally) hiding any functions.

arm: set uopSet_uop as conditional or unconditional control
uopSet_uop is microop instruction that has the IsControl flags set, but the
IsCondControl or IsUncondControl flags seems not to be set, neither in
the construction nor where the microop is used. This patch adds the the
flags in the constructor of the instruction (MicroUopSetPCCPSR).

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

ARM: Predict target of more instructions that modify PC.

ARM: Fix identification of one RAS pop instruction.

The check should be with the op2 field, not with the op1 field.

ARM: Fix case where cond/uncond control is mis-specified

gcc: Clean-up of non-C++0x compliant code, first steps

This patch cleans up a number of minor issues aiming to get closer to
compliance with the C++0x standard as interpreted by gcc and clang
(compile with std=c++0x and -pedantic-errors). In particular, the
patch cleans up enums where the last item was succeded by a comma,
namespaces closed by a curcly brace followed by a semi-colon, and the
use of the GNU-extension typeof (replaced by templated functions). It
does not address variable-length arrays, zero-size arrays, anonymous
structs, range expressions in switch statements, and the use of long
long. The generated CPU code also has a large number of issues that
remain to be fixed, mainly related to overflows in implicit constant
conversion (due to shifts).

ARM: Fix branch prediction issue with CB(N)Z instruction

clang: Enable compiling gem5 using clang 2.9 and 3.0

This patch adds the necessary flags to the SConstruct and SConscript
files for compiling using clang 2.9 and later (on Ubuntu et al and OSX
XCode 4.2), and also cleans up a bunch of compiler warnings found by
clang. Most of the warnings are related to hidden virtual functions,
comparisons with unsigneds >= 0, and if-statements with empty
bodies. A number of mismatches between struct and class are also
fixed. clang 2.8 is not working as it has problems with class names
that occur in multiple namespaces (e.g. Statistics in
kernel_stats.hh).

clang has a bug (http://llvm.org/bugs/show_bug.cgi?id=7247) which
causes confusion between the container std::set and the function
Packet::set, and this is currently addressed by not including the
entire namespace std, but rather selecting e.g. "using std::vector" in
the appropriate places.

GCC: Get everything working with gcc 4.6.1.

And by "everything" I mean all the quick regressions.

PseudoInst: Remove the now unnecessary #if FULL_SYSTEMs around pseudoinsts.

Fix bugs due to interaction between SEV instructions and O3 pipeline

SEV instructions were originally implemented to cause asynchronous squashes
via the generateTCSquash() function in the O3 pipeline when updating the
SEV_MAILBOX miscReg. This caused race conditions between CPUs in an MP system
that would lead to a pipeline either going inactive indefinitely or not being
able to commit squashed instructions. Fixed SEV instructions to behave like
interrupts and cause synchronous sqaushes inside the pipeline, eliminating
the race conditions. Also fixed up the semantics of the WFE instruction to
behave as documented in the ARMv7 ISA description to not sleep if SEV_MAILBOX=1
or unmasked interrupts are pending.

ExecContext: Rename the readBytes/writeBytes functions to readMem and writeMem.

readBytes and writeBytes had the word "bytes" in their names because they
accessed blobs of bytes. This distinguished them from the read and write
functions which handled higher level data types. Because those functions don't
exist any more, this change renames readBytes and writeBytes to more general
names, readMem and writeMem, which reflect the fact that they are how you read
and write memory. This also makes their names more consistent with the
register reading/writing functions, although those are still read and set for
some reason.

ISA: Use readBytes/writeBytes for all instruction level memory operations.

ARM: Further break up condition code into NZ, C, V bits.

Break up the condition code bits into NZ, C, V registers. These are individually
written and this removes some incorrect dependencies between instructions.

ARM: Break up condition codes into normal flags, saturation, and simd.

This change splits out the condcodes from being one monolithic register
into three blocks that are updated independently. This allows CPUs
to not have to do RMW operations on the flags registers for instructions
that don't write all flags.

ARM: Use CPU local lock before sending load to mem system.

This change uses the locked_mem.hh header to handle implementing CLREX. It
simplifies the current implementation greatly.

ARM: Fix bug in MicroLdrNeon templates for initiateAcc().

ARM: Cleanup implementation of ITSTATE and put important code in PCState.

Consolidate all code to handle ITSTATE in the PCState object rather than
touching a variety of structures/objects.

ARM: Tag appropriate instructions as IsReturn

ARM: Identify branches as conditional or unconditional and direct or indirect.

ARM: Allow conditional quiesce instructions.

This patch prevents not executed conditional instructions marked as
IsQuiesce from stalling the pipeline indefinitely. If the instruction
is not executed the quiesceSkip psuedoinst is called which schedules a
wakes up call to the fetch stage.

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: NEON instruction templates modified to set the predicate flag to false when needed.

ARM: Add support for moving predicated false dest operands from sources.

ARM: Make all ARM uops delayed commit.

ISA: Simplify various implementations of completeAcc.

ARM: Don't pretend to writeback registers in initiateAcc.

Mem: Change the CLREX flag to CLEAR_LL.

CLREX is the name of an ARM instruction, not a name for this generic flag.

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: Fix VFP enabled checks for mem instructions

ARM: Fix type comparison warnings in Neon.

ARM: Implement CPACR register and return Undefined Instruction when FP access is disabled.

ARM: Implement all ARM SIMD instructions.

MEM: Make CLREX a first class request operation and clear locks in caches when it in received

ARM: Don't write tracedata on writes, it might have been freed already.

ARM: Implement CLREX init/complete acc methods

ARM/O3: store the result of the predicate evaluation in DynInst or Threadstate.
THis allows the CPU to handle predicated-false instructions accordingly.
This particular patch makes loads that are predicated-false to be sent
straight to the commit stage directly, not waiting for return of the data
that was never requested since it was predicated-false.

ARM: Fix IT state not updating when an instruction memory instruction faults.

ARM: Decode to specialized conditional/unconditional versions of instructions.

This is to avoid condition code based dependences from effectively serializing
instructions when the instruction doesn't actually use them.

ARM: Implement support for the IT instruction and the ITSTATE bits of CPSR.

ARM: Clean up the implementation of the VFP instructions.

ARM: Introduce new VFP base classes that are optionally microops.

ARM: Add a new RegImmOp base class.

ARM: Add a RegRegImmOp base class.

ARM: Widen the immediate fields in the misc instruction classes.

ARM: Add a base class for SRS.

ARM: Make a base class for instructions that use only an immediate.

ARM: Implement the strex instructions.

ARM: Add a base class for the RFE instruction.

ARM: Explicitly keep track of the second destination for double loads/stores.

ARM: Rename the RevOp base class to something more generic.

ARM: Add a register, immediate, immediate to register base for [su]bfx.

ARM: Add a base class to support usada8.

ARM: Add a base class for the sel instruction.

ARM: Add a base class for extend and add instructions.

ARM: Generalize the saturation instruction bases for use in other instructions.

ARM: Implement base classes for the saturation instructions.

ARM: Add base classes suitable for the REV* instructions.

ARM: Implement the swp and swpb instructions.

ARM: Define versions of MSR and MRS outside the decoder.

ARM: Add templates for VFP load/store multiple instructions.

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.

ARM: Make macroops panic if executed directly.
The macroop should never be executed, only it's microops will.

ARM: GCC < 4.3 has some issues with attribute no return on some functions. Fix so it works for older gccs.

ARM: Split out the "basic" templates and format.

ARM: Add templates for multiply instructions.

ARM: Add new templates for branch instructions.

ARM: Implement data processing instructions external to the decoder.

ARM: Reimplement load/store multiple external to the decoder.

ARM: Move the templates for predicated instructions into a separate file.
This allows the templates to all be available at the same time before any of
the formats, etc. This breaks an artificial circular dependence.

ARM: Define the store instructions from outside the decoder.

ARM: Define the load instructions from outside the decoder.