src/arch/x86/predecoder.hh

   1 /*
   2  * Copyright (c) 2007 The Hewlett-Packard Development Company
   3  * All rights reserved.
   4  *
   5  * Redistribution and use of this software in source and binary forms,
   6  * with or without modification, are permitted provided that the
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   8  *
   9  * The software must be used only for Non-Commercial Use which means any
  10  * use which is NOT directed to receiving any direct monetary
  11  * compensation for, or commercial advantage from such use.  Illustrative
  12  * examples of non-commercial use are academic research, personal study,
  13  * teaching, education and corporate research & development.
  14  * Illustrative examples of commercial use are distributing products for
  15  * commercial advantage and providing services using the software for
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  17  *
  18  * If you wish to use this software or functionality therein that may be
  19  * covered by patents for commercial use, please contact:
  20  *     Director of Intellectual Property Licensing
  21  *     Office of Strategy and Technology
  22  *     Hewlett-Packard Company
  23  *     1501 Page Mill Road
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  31  * the COPYRIGHT HOLDER(s), HEWLETT-PACKARD COMPANY, nor the names of its
  32  * contributors may be used to endorse or promote products derived from
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  39  * and (ii) such Derivatives of the software include the above copyright
  40  * notice to acknowledge the contribution from this software where
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  42  *
  43  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  44  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  45  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  46  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  47  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  48  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  49  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  50  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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  53  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  54  *
  55  * Authors: Gabe Black
  56  */
  57
  58 #ifndef __ARCH_X86_PREDECODER_HH__
  59 #define __ARCH_X86_PREDECODER_HH__
  60
  61 #include <cassert>
  62
  63 #include "arch/x86/types.hh"
  64 #include "arch/x86/miscregs.hh"
  65 #include "base/bitfield.hh"
  66 #include "base/misc.hh"
  67 #include "base/trace.hh"
  68 #include "base/types.hh"
  69
  70 class ThreadContext;
  71
  72 namespace X86ISA
  73 {
  74     class Predecoder
  75     {
  76       private:
  77         //These are defined and documented in predecoder_tables.cc
  78         static const uint8_t Prefixes[256];
  79         static const uint8_t UsesModRM[2][256];
  80         static const uint8_t ImmediateType[2][256];
  81         static const uint8_t SizeTypeToSize[3][10];
  82
  83       protected:
  84         ThreadContext * tc;
  85         //The bytes to be predecoded
  86         MachInst fetchChunk;
  87         //The pc of the start of fetchChunk
  88         Addr basePC;
  89         //The pc the current instruction started at
  90         Addr origPC;
  91         //The offset into fetchChunk of current processing
  92         int offset;
  93         //The extended machine instruction being generated
  94         ExtMachInst emi;
  95         HandyM5Reg m5Reg;
  96
  97         inline uint8_t getNextByte()
  98         {
  99             return ((uint8_t *)&fetchChunk)[offset];
 100         }
 101
 102         void getImmediate(int &collected, uint64_t &current, int size)
 103         {
 104             //Figure out how many bytes we still need to get for the
 105             //immediate.
 106             int toGet = size - collected;
 107             //Figure out how many bytes are left in our "buffer"
 108             int remaining = sizeof(MachInst) - offset;
 109             //Get as much as we need, up to the amount available.
 110             toGet = toGet > remaining ? remaining : toGet;
 111
 112             //Shift the bytes we want to be all the way to the right
 113             uint64_t partialImm = fetchChunk >> (offset * 8);
 114             //Mask off what we don't want
 115             partialImm &= mask(toGet * 8);
 116             //Shift it over to overlay with our displacement.
 117             partialImm <<= (immediateCollected * 8);
 118             //Put it into our displacement
 119             current |= partialImm;
 120             //Update how many bytes we've collected.
 121             collected += toGet;
 122             consumeBytes(toGet);
 123         }
 124
 125         inline void consumeByte()
 126         {
 127             offset++;
 128             assert(offset <= sizeof(MachInst));
 129             if(offset == sizeof(MachInst))
 130                 outOfBytes = true;
 131         }
 132
 133         inline void consumeBytes(int numBytes)
 134         {
 135             offset += numBytes;
 136             assert(offset <= sizeof(MachInst));
 137             if(offset == sizeof(MachInst))
 138                 outOfBytes = true;
 139         }
 140
 141         void doReset();
 142
 143         //State machine state
 144       protected:
 145         //Whether or not we're out of bytes
 146         bool outOfBytes;
 147         //Whether we've completed generating an ExtMachInst
 148         bool emiIsReady;
 149         //The size of the displacement value
 150         int displacementSize;
 151         //The size of the immediate value
 152         int immediateSize;
 153         //This is how much of any immediate value we've gotten. This is used
 154         //for both the actual immediate and the displacement.
 155         int immediateCollected;
 156
 157         enum State {
 158             ResetState,
 159             PrefixState,
 160             OpcodeState,
 161             ModRMState,
 162             SIBState,
 163             DisplacementState,
 164             ImmediateState,
 165             //We should never get to this state. Getting here is an error.
 166             ErrorState
 167         };
 168
 169         State state;
 170
 171         //Functions to handle each of the states
 172         State doPrefixState(uint8_t);
 173         State doOpcodeState(uint8_t);
 174         State doModRMState(uint8_t);
 175         State doSIBState(uint8_t);
 176         State doDisplacementState();
 177         State doImmediateState();
 178
 179       public:
 180         Predecoder(ThreadContext * _tc) :
 181             tc(_tc), basePC(0), origPC(0), offset(0),
 182             outOfBytes(true), emiIsReady(false),
 183             state(ResetState)
 184         {
 185             emi.mode.mode = LongMode;
 186             emi.mode.submode = SixtyFourBitMode;
 187             m5Reg = 0;
 188         }
 189
 190         void reset()
 191         {
 192             state = ResetState;
 193         }
 194
 195         ThreadContext * getTC()
 196         {
 197             return tc;
 198         }
 199
 200         void setTC(ThreadContext * _tc)
 201         {
 202             tc = _tc;
 203         }
 204
 205         void process();
 206
 207         //Use this to give data to the predecoder. This should be used
 208         //when there is control flow.
 209         void moreBytes(Addr pc, Addr fetchPC, MachInst data)
 210         {
 211             DPRINTF(Predecoder, "Getting more bytes.\n");
 212             basePC = fetchPC;
 213             offset = (fetchPC >= pc) ? 0 : pc - fetchPC;
 214             fetchChunk = data;
 215             outOfBytes = false;
 216             process();
 217         }
 218
 219         bool needMoreBytes()
 220         {
 221             return outOfBytes;
 222         }
 223
 224         bool extMachInstReady()
 225         {
 226             return emiIsReady;
 227         }
 228
 229         //This returns a constant reference to the ExtMachInst to avoid a copy
 230         const ExtMachInst & getExtMachInst()
 231         {
 232             assert(emiIsReady);
 233             emiIsReady = false;
 234             return emi;
 235         }
 236
 237         int getInstSize()
 238         {
 239             DPRINTF(Predecoder,
 240                     "Calculating the instruction size: "
 241                     "basePC: %#x offset: %#x origPC: %#x\n",
 242                     basePC, offset, origPC);
 243             return basePC + offset - origPC;
 244         }
 245     };
 246 };
 247
 248 #endif // __ARCH_X86_PREDECODER_HH__