b7b545bc38
This change pulls the instruction decoding machinery (including caches) out of the StaticInst class and puts it into its own class. This has a few intrinsic benefits. First, the StaticInst code, which has gotten to be quite large, gets simpler. Second, the code that handles decode caching is now separated out into its own component and can be looked at in isolation, making it easier to understand. I took the opportunity to restructure the code a bit which will hopefully also help. Beyond that, this change also lays some ground work for each ISA to have its own, potentially stateful decode object. We'd be able to include less contextualizing information in the ExtMachInst objects since that context would be applied at the decoder. Also, the decoder could "know" ahead of time that all the instructions it's going to see are going to be, for instance, 64 bit mode, and it will have one less thing to check when it decodes them. Because the decode caching mechanism has been separated out, it's now possible to have multiple caches which correspond to different types of decoding context. Having one cache for each element of the cross product of different configurations may become prohibitive, so it may be desirable to clear out the cache when relatively static state changes and not to have one for each setting. Because the decode function is no longer universally accessible as a static member of the StaticInst class, a new function was added to the ThreadContexts that returns the applicable decode object.
59 lines
2.3 KiB
C++
59 lines
2.3 KiB
C++
/*
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* Copyright (c) 2011 Google
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Gabe Black
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*/
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#ifndef __CPU_DECODE_HH__
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#define __CPU_DECODE_HH__
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#include "arch/isa_traits.hh"
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#include "arch/types.hh"
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#include "config/the_isa.hh"
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#include "cpu/decode_cache.hh"
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#include "cpu/static_inst.hh"
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/// The decoder class. This class doesn't do much of anything now, but in the
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/// future it will be redefinable per ISA and allow more interesting behavior.
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class Decoder
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{
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protected:
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/// A cache of decoded instruction objects.
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static DecodeCache<TheISA::decodeInst> cache;
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public:
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/// Decode a machine instruction.
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/// @param mach_inst The binary instruction to decode.
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/// @retval A pointer to the corresponding StaticInst object.
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StaticInstPtr
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decode(TheISA::ExtMachInst mach_inst, Addr addr)
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{
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return cache.decode(mach_inst, addr);
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}
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};
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#endif // __CPU_DECODE_HH__
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