path: root/utils/TableGen/AsmWriterEmitter.cpp

//===- AsmWriterEmitter.cpp - Generate an assembly writer -----------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This tablegen backend is emits an assembly printer for the current target.
// Note that this is currently fairly skeletal, but will grow over time.
//
//===----------------------------------------------------------------------===//

#include "AsmWriterEmitter.h"
#include "AsmWriterInst.h"
#include "CodeGenTarget.h"
#include "StringToOffsetTable.h"
#include "SequenceToOffsetTable.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/TableGen/Error.h"
#include "llvm/TableGen/Record.h"
#include <algorithm>
using namespace llvm;

static void PrintCases(std::vector<std::pair<std::string,
                       AsmWriterOperand> > &OpsToPrint, raw_ostream &O) {
  O << "    case " << OpsToPrint.back().first << ": ";
  AsmWriterOperand TheOp = OpsToPrint.back().second;
  OpsToPrint.pop_back();

  // Check to see if any other operands are identical in this list, and if so,
  // emit a case label for them.
  for (unsigned i = OpsToPrint.size(); i != 0; --i)
    if (OpsToPrint[i-1].second == TheOp) {
      O << "\n    case " << OpsToPrint[i-1].first << ": ";
      OpsToPrint.erase(OpsToPrint.begin()+i-1);
    }

  // Finally, emit the code.
  O << TheOp.getCode();
  O << "break;\n";
}


/// EmitInstructions - Emit the last instruction in the vector and any other
/// instructions that are suitably similar to it.
static void EmitInstructions(std::vector<AsmWriterInst> &Insts,
                             raw_ostream &O) {
  AsmWriterInst FirstInst = Insts.back();
  Insts.pop_back();

  std::vector<AsmWriterInst> SimilarInsts;
  unsigned DifferingOperand = ~0;
  for (unsigned i = Insts.size(); i != 0; --i) {
    unsigned DiffOp = Insts[i-1].MatchesAllButOneOp(FirstInst);
    if (DiffOp != ~1U) {
      if (DifferingOperand == ~0U)  // First match!
        DifferingOperand = DiffOp;

      // If this differs in the same operand as the rest of the instructions in
      // this class, move it to the SimilarInsts list.
      if (DifferingOperand == DiffOp || DiffOp == ~0U) {
        SimilarInsts.push_back(Insts[i-1]);
        Insts.erase(Insts.begin()+i-1);
      }
    }
  }

  O << "  case " << FirstInst.CGI->Namespace << "::"
    << FirstInst.CGI->TheDef->getName() << ":\n";
  for (unsigned i = 0, e = SimilarInsts.size(); i != e; ++i)
    O << "  case " << SimilarInsts[i].CGI->Namespace << "::"
      << SimilarInsts[i].CGI->TheDef->getName() << ":\n";
  for (unsigned i = 0, e = FirstInst.Operands.size(); i != e; ++i) {
    if (i != DifferingOperand) {
      // If the operand is the same for all instructions, just print it.
      O << "    " << FirstInst.Operands[i].getCode();
    } else {
      // If this is the operand that varies between all of the instructions,
      // emit a switch for just this operand now.
      O << "    switch (MI->getOpcode()) {\n";
      std::vector<std::pair<std::string, AsmWriterOperand> > OpsToPrint;
      OpsToPrint.push_back(std::make_pair(FirstInst.CGI->Namespace + "::" +
                                          FirstInst.CGI->TheDef->getName(),
                                          FirstInst.Operands[i]));

      for (unsigned si = 0, e = SimilarInsts.size(); si != e; ++si) {
        AsmWriterInst &AWI = SimilarInsts[si];
        OpsToPrint.push_back(std::make_pair(AWI.CGI->Namespace+"::"+
                                            AWI.CGI->TheDef->getName(),
                                            AWI.Operands[i]));
      }
      std::reverse(OpsToPrint.begin(), OpsToPrint.end());
      while (!OpsToPrint.empty())
        PrintCases(OpsToPrint, O);
      O << "    }";
    }
    O << "\n";
  }
  O << "    break;\n";
}

void AsmWriterEmitter::
FindUniqueOperandCommands(std::vector