//===- MappingInfo.cpp - create LLVM info and output to .s file ---------===//
//
// This file contains a FunctionPass called MappingInfo,
// which creates two maps: one between LLVM Instructions and MachineInstrs
// (the "LLVM I TO MI MAP"), and another between MachineBasicBlocks and
// MachineInstrs (the "BB TO MI MAP").
//
// As a side effect, it outputs this information as .byte directives to
// the assembly file. The output is designed to survive the SPARC assembler,
// in order that the Reoptimizer may read it in from memory later when the
// binary is loaded. Therefore, it may contain some hidden SPARC-architecture
// dependencies. Currently this question is purely theoretical as the
// Reoptimizer works only on the SPARC.
//
// The LLVM I TO MI MAP consists of a set of information for each
// BasicBlock in a Function, ordered from begin() to end(). The information
// for a BasicBlock consists of
//  1) its (0-based) index in the Function,
//  2) the number of LLVM Instructions it contains, and
//  3) information for each Instruction, in sequence from the begin()
//     to the end() of the BasicBlock. The information for an Instruction
//     consists of
//     1) its (0-based) index in the BasicBlock,
//     2) the number of MachineInstrs that correspond to that Instruction
//        (as reported by MachineCodeForInstruction), and
//     3) the MachineInstr number calculated by create_MI_to_number_Key,
//        for each of the MachineInstrs that correspond to that Instruction.
//
// The BB TO MI MAP consists of a three-element tuple for each
// MachineBasicBlock in a function, ordered from begin() to end() of
// its MachineFunction: first, the index of the MachineBasicBlock in the
// function; second, the number of the MachineBasicBlock in the function
// as computed by create_BB_to_MInumber_Key; and third, the number of
// MachineInstrs in the MachineBasicBlock.
//
//===--------------------------------------------------------------------===//

#include "MappingInfo.h"
#include "llvm/Pass.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineCodeForInstruction.h"

namespace {
  class MappingInfoCollector : public FunctionPass { 
    std::ostream &Out;
  public:
    MappingInfoCollector(std::ostream &out) : Out(out){}
    const char *getPassName () const { return "Instr. Mapping Info Collector"; }
    bool runOnFunction(Function &FI);
    typedef std::map<const MachineInstr*, unsigned> InstructionKey;
  private:
    MappingInfo *currentOutputMap;
    std::map<Function *, unsigned> Fkey; // Function # for all functions.
    bool doInitialization(Module &M);
    void create_BB_to_MInumber_Key(Function &FI, InstructionKey &key);
    void create_MI_to_number_Key(Function &FI, InstructionKey &key);
    void buildBBMIMap (Function &FI, MappingInfo &Map);
    void buildLMIMap (Function &FI, MappingInfo &Map);
    void writeNumber(unsigned X);
    void selectOutputMap (MappingInfo &m) { currentOutputMap = &m; }
    void outByte (unsigned char b) { currentOutputMap->outByte (b); }
  };
}

/// getMappingInfoCollector -- Static factory method: returns a new
/// MappingInfoCollector Pass object, which uses OUT as its
/// output stream for assembly output. 
Pass *getMappingInfoCollector(std::ostream &out){
  return (new MappingInfoCollector(out));
}

/// runOnFunction -- Builds up the maps for the given function FI and then
/// writes them out as assembly code to the current output stream OUT.
/// This is an entry point to the pass, called by the PassManager.
bool MappingInfoCollector::runOnFunction(Function &FI) {
  unsigned num = Fkey[&FI]; // Function number for the current function.

  // Create objects to hold the maps.
  MappingInfo LMIMap ("LLVM I TO MI MAP", "LMIMap", num);
  MappingInfo BBMIMap ("BB TO MI MAP", "BBMIMap", num);

  // Now, build the maps.
  buildLMIMap (FI, LMIMap);
  buildBBMIMap (FI, BBMIMap);

  // Now, write out the maps.
  LMIMap.dumpAssembly (Out);
  BBMIMap.dumpAssembly (Out);

  return false; 
}  

/// writeNumber -- Write out the number X as a sequence of .byte
/// directives to the current output stream Out. This method performs a
/// run-length encoding of the unsigned integers X that are output.
void MappingInfoCollector::writeNumber(unsigned X) {
  unsigned i=0;
  do {
    unsigned tmp = X & 127;
    X >>= 7;
    if (X) tmp |= 128;
    outByte (tmp);
    ++i;
  } while(X);
}

/// doInitialization -- Assign a number to each Function, as follows:
/// Functions are numbered starting at 0 at the begin() of each Module.
/// Functions which are External (and thus have 0 basic blocks) are not
/// inserted into the maps, and are not assigned a number.  The side-effect
/// of this method is to fill in Fkey to contain the mapping from Functions
/// to numbers. (This method is called automatically by the PassManager.)
bool MappingInfoCollector::doInitialization(Module &M) {
  unsigned i = 0;
  for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI) {
    if (FI->isExternal()) continue;
    Fkey[FI] = i;
    ++i;
  }
  return false; // Success.
}

/// create_BB_to_MInumber_Key -- Assign a number to each MachineBasicBlock
/// in the given Function, as follows: Numbering starts at zero in each
/// Function. MachineBasicBlocks are numbered from begin() to end()
/// in the Function's corresponding MachineFunction. Each successive
/// MachineBasicBlock increments the numbering by the number of instructions
/// it contains. The side-effect of this method is to fill in the paramete
/// KEY with the mapping of MachineBasicBlocks to numbers. KEY
/// is keyed on MachineInstrs, so each MachineBasicBlock is represented
/// therein by its first MachineInstr.
void MappingInfoCollector::create_BB_to_MInumber_Key(Function &FI,
                                                     InstructionKey &key) {
  unsigned i = 0;
  MachineFunction &MF = MachineFunction::get(&FI);
  for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
       BI != BE; ++BI) {
    MachineBasicBlock &miBB = *BI;
    key[miBB[0]] = i;
    i = i+(miBB.size());
  }
}

/// create_MI_to_number_Key -- Assign a number to each MachineInstr
/// in the given Function with respect to its enclosing MachineBasicBlock, as
/// follows: Numberings start at 0 in each MachineBasicBlock. MachineInstrs
/// are numbered from begin() to end() in their MachineBasicBlock. Each
/// MachineInstr is numbered, then the numbering is incremented by 1. The
/// side-effect of this method is to fill in the parameter KEY
/// with the mapping from MachineInstrs to numbers.
void MappingInfoCollector::create_MI_to_number_Key(Function &FI,
                                                   InstructionKey &key) {
  MachineFunction &MF = MachineFunction::get(&FI);
  for (MachineFunction::iterator BI=MF.begin(), BE=MF.end(); BI != BE; ++BI) {
    MachineBasicBlock &miBB = *BI;
    unsigned j = 0;
    for(MachineBasicBlock::iterator miI = miBB.begin(), miE = miBB.end();
        miI != miE; ++miI, ++j) {
      key[*miI] = j;
    }
  }
}

/// buildBBMIMap -- Build the BB TO MI MAP for the function FI,
/// and save it into the parameter MAP.
void MappingInfoCollector::buildBBMIMap(Function &FI, MappingInfo &Map) {
  unsigned bb = 0;

  // First build temporary table used to write out the map.
  InstructionKey BBkey;
  create_BB_to_MInumber_Key(FI, BBkey);

  selectOutputMap (Map);
  MachineFunction &MF = MachineFunction::get(&FI);  
  for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
       BI != BE; ++BI, ++bb) {
    MachineBasicBlock &miBB = *BI;
    writeNumber(bb);
    writeNumber(BBkey[miBB[0]]);
    writeNumber(miBB.size());
  }
}

/// buildLMIMap -- Build the LLVM I TO MI MAP for the function FI,
/// and save it into the parameter MAP.
void MappingInfoCollector::buildLMIMap(Function &FI, MappingInfo &Map) {
  unsigned bb = 0;
  // First build temporary table used to write out the map.
  InstructionKey MIkey;
  create_MI_to_number_Key(FI, MIkey);

  selectOutputMap (Map);
  for (Function::iterator BI = FI.begin(), BE = FI.end(); 
       BI != BE; ++BI, ++bb) {
    unsigned li = 0;
    writeNumber(bb);
    writeNumber(BI->size());
    for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;
         ++II, ++li) {
      MachineCodeForInstruction& miI = MachineCodeForInstruction::get(II);
      writeNumber(li);
      writeNumber(miI.size());
      for (MachineCodeForInstruction::iterator miII = miI.begin(), 
           miIE = miI.end(); miII != miIE; ++miII) {
	     writeNumber(MIkey[*miII]);
      }
    }
  } 
}

void MappingInfo::byteVector::dumpAssembly (std::ostream &Out) {
  for (iterator i = begin (), e = end (); i != e; ++i)
	Out << ".byte " << (int)*i << "\n";
}

void MappingInfo::dumpAssembly (std::ostream &Out) {
  // Prologue:
  // Output a comment describing the map.
  Out << "!" << comment << "\n";   
  // Switch the current section to .rodata in the assembly output:
  Out << "\t.section \".rodata\"\n\t.align 8\n";  
  // Output a global symbol naming the map:
  Out << "\t.global " << symbolPrefix << functionNumber << "\n";    
  Out << "\t.type " << symbolPrefix << functionNumber << ",#object\n"; 
  Out << symbolPrefix << functionNumber << ":\n"; 
  // Output a word containing the length of the map:
  Out << "\t.word .end_" << symbolPrefix << functionNumber << "-"
      << symbolPrefix << functionNumber << "\n";

  // Output the map data itself:
  bytes.dumpAssembly (Out);

  // Epilogue:
  // Output a local symbol marking the end of the map:
  Out << ".end_" << symbolPrefix << functionNumber << ":\n";    
  // Output size directive giving the size of the map:
  Out << "\t.size " << symbolPrefix << functionNumber << ", .end_" 
      << symbolPrefix << functionNumber << "-" << symbolPrefix 
      << functionNumber << "\n\n";
}