live_mregs.h

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// Copyright (c) 2021-2023, David H. Hovemeyer <david.hovemeyer@gmail.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
 
#ifndef LIVE_MREGS_H
#define LIVE_MREGS_H
 
#include <string>
#include "instruction.h"
#include "lowlevel_defuse.h"
#include "lowlevel_formatter.h"
#include "dataflow.h"
 
 
class LiveMregsAnalysis : public BackwardAnalysis {
public:
  // There are only 16 mregs
  static const unsigned MAX_MREGS = 16;
 
  typedef std::bitset<MAX_MREGS> FactType;
 
  FactType get_top_fact() const { return FactType(); }
 
  FactType combine_facts(const FactType &left, const FactType &right) const {
    return left | right;
  }
 
  void model_instruction(Instruction *ins, FactType &fact) const {
    // Model an instruction (backwards).  If the instruction is a def,
    // the assigned-to mreg is killed.  Every mreg used in the instruction,
    // the mreg becomes alive (or is kept alive.)
 
    if (LowLevel::is_def(ins)) {
      std::vector<MachineReg> defs = LowLevel::get_def_mregs(ins);
      for (auto i = defs.begin(); i != defs.end(); ++i)
        fact.reset(unsigned(*i));
    }
 
    std::vector<MachineReg> uses = LowLevel::get_use_mregs(ins);
    for (auto i = uses.begin(); i != uses.end(); ++i)
      fact.set(unsigned(*i));
  }
 
  std::string fact_to_string(const FactType &fact) const {
    LowLevelFormatter ll_formatter;
 
    std::string s("{");
    for (unsigned i = 0; i < MAX_MREGS; i++) {
      if (fact.test(i)) {
        if (s != "{") { s += ","; }
        // Machine registers are shown using their 64-bit name
        Operand mreg_operand(Operand::MREG64, i);
        s += ll_formatter.format_operand(mreg_operand);
      }
    }
    s += "}";
    return s;
  }
};
 
typedef Dataflow<LiveMregsAnalysis> LiveMregs;
 
#endif // LIVE_MREGS_H