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arch,cpu: Create register class descriptors.

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These currently only hold the number of registers in a particular class,
but can be extended in the future to hold other information about each
class. The ISA class holds a vector of descriptors which other parts of
gem5 can retrieve to set up storage for each class, etc.

Currently, the RegClass enum is used to explicitly index into the vector
of descriptors to get information about a particular class. Once enough
information is stored in the descriptors, the other parts of gem5 should
be able to set up for each register class generically, and the ISAs will
be able to leave out or create new register classes without having to
set up global plumbing for it.

The more immediate benefit is that this should (mostly) parameterize
away the ISA register constants to break another TheISA style
dependency. Currently a global set of descriptors are set up in the
BaseISA class using the old TheISA constants, but it should be easy to
break those out and make the ISAs set up their own descriptors. That
will bring arch/registers.hh significantly closer to being eliminated.

Change-Id: I6d6d1256288f880391246b71045482a4a03c4198
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/41733
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Gabe Black
2021-02-21 06:39:04 -08:00
parent e837fdc65c
commit 49082c971f
15 changed files with 247 additions and 165 deletions
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19
src/cpu/simple_thread.cc
View File

@@ -74,22 +74,19 @@ SimpleThread::SimpleThread(BaseCPU *_cpu, int _thread_num, System *_sys,
htmTransactionStarts(0), htmTransactionStops(0)
{
assert(isa);
const auto &regClasses = isa->regClasses();
intRegs.resize(regClasses.at(IntRegClass).size());
floatRegs.resize(regClasses.at(FloatRegClass).size());
vecRegs.resize(regClasses.at(VecRegClass).size());
vecPredRegs.resize(regClasses.at(VecPredRegClass).size());
ccRegs.resize(regClasses.at(CCRegClass).size());
clearArchRegs();
}
SimpleThread::SimpleThread(BaseCPU *_cpu, int _thread_num, System *_sys,
BaseMMU *_mmu, BaseISA *_isa)
: ThreadState(_cpu, _thread_num, NULL),
isa(dynamic_cast<TheISA::ISA *>(_isa)),
predicate(true), memAccPredicate(true),
comInstEventQueue("instruction-based event queue"),
system(_sys), mmu(_mmu), decoder(isa),
htmTransactionStarts(0), htmTransactionStops(0)
{
assert(isa);
clearArchRegs();
}
: SimpleThread(_cpu, _thread_num, _sys, nullptr, _mmu, _isa)
{}
void
SimpleThread::takeOverFrom(ThreadContext *oldContext)