dynarmic/src/frontend/ir/terminal.h
2020-04-22 20:33:30 +01:00

107 lines
3.2 KiB
C++

/* This file is part of the dynarmic project.
* Copyright (c) 2016 MerryMage
* This software may be used and distributed according to the terms of the GNU
* General Public License version 2 or any later version.
*/
#pragma once
#include <boost/variant.hpp>
#include "common/common_types.h"
#include "frontend/ir/cond.h"
#include "frontend/ir/location_descriptor.h"
namespace Dynarmic {
namespace IR {
namespace Term {
struct Invalid {};
/**
* This terminal instruction calls the interpreter, starting at `next`.
* The interpreter must interpret exactly one instruction.
*/
struct Interpret {
explicit Interpret(const LocationDescriptor& next_) : next(next_) {}
LocationDescriptor next; ///< Location at which interpretation starts.
};
/**
* This terminal instruction returns control to the dispatcher.
* The dispatcher will use the value in R15 to determine what comes next.
*/
struct ReturnToDispatch {};
/**
* This terminal instruction jumps to the basic block described by `next` if we have enough
* cycles remaining. If we do not have enough cycles remaining, we return to the
* dispatcher, which will return control to the host.
*/
struct LinkBlock {
explicit LinkBlock(const LocationDescriptor& next_) : next(next_) {}
LocationDescriptor next; ///< Location descriptor for next block.
};
/**
* This terminal instruction jumps to the basic block described by `next` unconditionally.
* This is an optimization and MUST only be emitted when this is guaranteed not to result
* in hanging, even in the face of other optimizations. (In practice, this means that only
* forward jumps to short-ish blocks would use this instruction.)
* A backend that doesn't support this optimization may choose to implement this exactly
* as LinkBlock.
*/
struct LinkBlockFast {
explicit LinkBlockFast(const LocationDescriptor& next_) : next(next_) {}
LocationDescriptor next; ///< Location descriptor for next block.
};
/**
* This terminal instruction checks the top of the Return Stack Buffer against R15.
* If RSB lookup fails, control is returned to the dispatcher.
* This is an optimization for faster function calls. A backend that doesn't support
* this optimization or doesn't have a RSB may choose to implement this exactly as
* ReturnToDispatch.
*/
struct PopRSBHint {};
struct If;
struct CheckHalt;
/// A Terminal is the terminal instruction in a MicroBlock.
using Terminal = boost::variant<
Invalid,
Interpret,
ReturnToDispatch,
LinkBlock,
LinkBlockFast,
PopRSBHint,
boost::recursive_wrapper<If>,
boost::recursive_wrapper<CheckHalt>
>;
/**
* This terminal instruction conditionally executes one terminal or another depending
* on the run-time state of the ARM flags.
*/
struct If {
If(Cond if_, Terminal then_, Terminal else_) : if_(if_), then_(then_), else_(else_) {}
Cond if_;
Terminal then_;
Terminal else_;
};
/**
* This terminal instruction checks if a halt was requested. If it wasn't, else_ is
* executed.
*/
struct CheckHalt {
explicit CheckHalt(Terminal else_) : else_(else_) {}
Terminal else_;
};
} // namespace Term
using Term::Terminal;
} // namespace IR
} // namespace Dynarmic