MachineDebugInfo.cpp

//===-- llvm/CodeGen/MachineDebugInfo.cpp -----------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by James M. Laskey and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/MachineDebugInfo.h"

#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Intrinsics.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Support/Dwarf.h"

#include <iostream>

using namespace llvm;
using namespace llvm::dwarf;

// Handle the Pass registration stuff necessary to use TargetData's.
namespace {
  RegisterPass<MachineDebugInfo> X("machinedebuginfo", "Debug Information");
}

//===----------------------------------------------------------------------===//

/// getGlobalVariablesUsing - Return all of the GlobalVariables which have the
/// specified value in their initializer somewhere.
static void
getGlobalVariablesUsing(Value *V, std::vector<GlobalVariable*> &Result) {
  // Scan though value users.
  for (Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) {
    if (GlobalVariable *GV = dyn_cast<GlobalVariable>(*I)) {
      // If the user is a GlobalVariable then add to result.
      Result.push_back(GV);
    } else if (Constant *C = dyn_cast<Constant>(*I)) {
      // If the user is a constant variable then scan its users
      getGlobalVariablesUsing(C, Result);
    }
  }
}

/// getGlobalVariablesUsing - Return all of the GlobalVariables that use the
/// named GlobalVariable.
static std::vector<GlobalVariable*>
getGlobalVariablesUsing(Module &M, const std::string &RootName) {
  std::vector<GlobalVariable*> Result;  // GlobalVariables matching criteria.
  
  std::vector<const Type*> FieldTypes;
  FieldTypes.push_back(Type::UIntTy);
  FieldTypes.push_back(Type::UIntTy);

  // Get the GlobalVariable root.
  GlobalVariable *UseRoot = M.getGlobalVariable(RootName,
                                                StructType::get(FieldTypes));

  // If present and linkonce then scan for users.
  if (UseRoot && UseRoot->hasLinkOnceLinkage()) {
    getGlobalVariablesUsing(UseRoot, Result);
  }
  
  return Result;
}
  
/// getStringValue - Turn an LLVM constant pointer that eventually points to a
/// global into a string value.  Return an empty string if we can't do it.
///
static const std::string getStringValue(Value *V, unsigned Offset = 0) {
  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
    if (GV->hasInitializer() && isa<ConstantArray>(GV->getInitializer())) {
      ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
      if (Init->isString()) {
        std::string Result = Init->getAsString();
        if (Offset < Result.size()) {
          // If we are pointing INTO The string, erase the beginning...
          Result.erase(Result.begin(), Result.begin()+Offset);

          // Take off the null terminator, and any string fragments after it.
          std::string::size_type NullPos = Result.find_first_of((char)0);
          if (NullPos != std::string::npos)
            Result.erase(Result.begin()+NullPos, Result.end());
          return Result;
        }
      }
    }
  } else if (Constant *C = dyn_cast<Constant>(V)) {
    if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
      return getStringValue(GV, Offset);
    else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
      if (CE->getOpcode() == Instruction::GetElementPtr) {
        // Turn a gep into the specified offset.
        if (CE->getNumOperands() == 3 &&
            cast<Constant>(CE->getOperand(1))->isNullValue() &&
            isa<ConstantInt>(CE->getOperand(2))) {
          return getStringValue(CE->getOperand(0),
                   Offset+cast<ConstantInt>(CE->getOperand(2))->getRawValue());
        }
      }
    }
  }
  return "";
}

/// isStringValue - Return true if the given value can be coerced to a string.
///
static bool isStringValue(Value *V) {
  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
    if (GV->hasInitializer() && isa<ConstantArray>(GV->getInitializer())) {
      ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
      return Init->isString();
    }
  } else if (Constant *C = dyn_cast<Constant>(V)) {
    if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
      return isStringValue(GV);
    else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
      if (CE->getOpcode() == Instruction::GetElementPtr) {
        if (CE->getNumOperands() == 3 &&
            cast<Constant>(CE->getOperand(1))->isNullValue() &&
            isa<ConstantInt>(CE->getOperand(2))) {
          return isStringValue(CE->getOperand(0));
        }
      }
    }
  }
  return false;
}

/// getGlobalVariable - Return either a direct or cast Global value.
///
static GlobalVariable *getGlobalVariable(Value *V) {
  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
    return GV;
  } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
    if (CE->getOpcode() == Instruction::Cast) {
      return dyn_cast<GlobalVariable>(CE->getOperand(0));
    }
  }
  return NULL;
}

/// isGlobalVariable - Return true if the given value can be coerced to a
/// GlobalVariable.
static bool isGlobalVariable(Value *V) {
  if (isa<GlobalVariable>(V) || isa<ConstantPointerNull>(V)) {
    return true;
  } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
    if (CE->getOpcode() == Instruction::Cast) {
      return isa<GlobalVariable>(CE->getOperand(0));
    }
  }
  return false;
}

/// getUIntOperand - Return ith operand if it is an unsigned integer.
///
static ConstantUInt *getUIntOperand(GlobalVariable *GV, unsigned i) {
  // Make sure the GlobalVariable has an initializer.
  if (!GV->hasInitializer()) return NULL;
  
  // Get the initializer constant.
  ConstantStruct *CI = dyn_cast<ConstantStruct>(GV->getInitializer());
  if (!CI) return NULL;
  
  // Check if there is at least i + 1 operands.
  unsigned N = CI->getNumOperands();
  if (i >= N) return NULL;

  // Check constant.
  return dyn_cast<ConstantUInt>(CI->getOperand(i));
}
//===----------------------------------------------------------------------===//

/// ApplyToFields - Target the visitor to each field of the debug information
/// descriptor.
void DIVisitor::ApplyToFields(DebugInfoDesc *DD) {
  DD->ApplyToFields(this);
}

//===----------------------------------------------------------------------===//
/// DICountVisitor - This DIVisitor counts all the fields in the supplied debug
/// the supplied DebugInfoDesc.
class DICountVisitor : public DIVisitor {
private:
  unsigned Count;                       // Running count of fields.
  
public:
  DICountVisitor() : DIVisitor(), Count(0) {}
  
  // Accessors.
  unsigned getCount() const { return Count; }
  
  /// Apply - Count each of the fields.
  ///
  virtual void Apply(int &Field)             { ++Count; }
  virtual void Apply(unsigned &Field)        { ++Count; }