llvm/lib/VMCore/Mangler.cpp

//===-- Mangler.cpp - Self-contained c/asm llvm name mangler --------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Unified name mangler for CWriter and assembly backends.
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/Mangler.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
using namespace llvm;

static char HexDigit(int V) {
  return V < 10 ? V+'0' : V+'A'-10;
}

static std::string MangleLetter(unsigned char C) {
  char Result[] = { '_', HexDigit(C >> 4), HexDigit(C & 15), '_', 0 };
  return Result;
}

/// makeNameProper - We don't want identifier names non-C-identifier characters
/// in them, so mangle them as appropriate.
///
std::string Mangler::makeNameProper(const std::string &X, const char *Prefix) {
  std::string Result;
  if (X.empty()) return X;  // Empty names are uniqued by the caller.
  
  // If PreserveAsmNames is set, names with asm identifiers are not modified. 
  if (PreserveAsmNames && X[0] == 1)
    return X;
  
  if (!UseQuotes) {
    // If X does not start with (char)1, add the prefix.
    std::string::const_iterator I = X.begin();
    if (*I != 1)
      Result = Prefix;
    else
      ++I;  // Skip over the marker.
    
    // Mangle the first letter specially, don't allow numbers.
    if (*I >= '0' && *I <= '9')
      Result += MangleLetter(*I++);

    for (std::string::const_iterator E = X.end(); I != E; ++I) {
      if (!isCharAcceptable(*I))
        Result += MangleLetter(*I);
      else
        Result += *I;
    }
  } else {
    bool NeedsQuotes = false;
    
    std::string::const_iterator I = X.begin();
    if (*I == 1)
      ++I;  // Skip over the marker.

    // If the first character is a number, we need quotes.
    if (*I >= '0' && *I <= '9')
      NeedsQuotes = true;
    
    // Do an initial scan of the string, checking to see if we need quotes or
    // to escape a '"' or not.
    if (!NeedsQuotes)
      for (std::string::const_iterator E = X.end(); I != E; ++I)
        if (!isCharAcceptable(*I)) {
          NeedsQuotes = true;
          break;
        }
    
    // In the common case, we don't need quotes.  Handle this quickly.
    if (!NeedsQuotes) {
      if (*X.begin() != 1)
        return Prefix+X;
      else
        return X.substr(1);
    }
    
    // Otherwise, construct the string the expensive way.
    I = X.begin();
    
    // If X does not start with (char)1, add the prefix.
    if (*I != 1)
      Result = Prefix;
    else
      ++I;   // Skip the marker if present.
      
    for (std::string::const_iterator E = X.end(); I != E; ++I) {
      if (*I == '"')
        Result += "_QQ_";
      else if (*I == '\n')
        Result += "_NL_";
      else
        Result += *I;
    }
    Result = '"' + Result + '"';
  }
  return Result;
}

/// getTypeID - Return a unique ID for the specified LLVM type.
///
unsigned Mangler::getTypeID(const Type *Ty) {
  unsigned &E = TypeMap[Ty];
  if (E == 0) E = ++TypeCounter;
  return E;
}

std::string Mangler::getValueName(const Value *V) {
  if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
    return getValueName(GV);
  
  std::string &Name = Memo[V];
  if (!Name.empty())
    return Name;       // Return the already-computed name for V.
  
  // Always mangle local names.
  Name = "ltmp_" + utostr(Count++) + "_" + utostr(getTypeID(V->getType()));
  return Name;
}


std::string Mangler::getValueName(const GlobalValue *GV, const char * Suffix) {
  // Check to see whether we've already named V.
  std::string &Name = Memo[GV];
  if (!Name.empty())
    return Name;       // Return the already-computed name for V.

  // Name mangling occurs as follows:
  // - If V is an intrinsic function, do not change name at all
  // - Otherwise, mangling occurs if global collides with existing name.
  if (isa<Function>(GV) && cast<Function>(GV)->isIntrinsic()) {
    Name = GV->getNameStart(); // Is an intrinsic function
  } else if (!GV->hasName()) {
    // Must mangle the global into a unique ID.
    unsigned TypeUniqueID = getTypeID(GV->getType());
    static unsigned GlobalID = 0;
    Name = "__unnamed_" + utostr(TypeUniqueID) + "_" + utostr(GlobalID++);
  } else if (!MangledGlobals.count(GV)) {
    Name = makeNameProper(GV->getName() + Suffix, Prefix);
  } else {
    unsigned TypeUniqueID = getTypeID(GV->getType());
    Name = "l" + utostr(TypeUniqueID) + "_" + makeNameProper(GV->getName());
  }

  return Name;
}

static void InsertName(GlobalValue *GV, StringMap<GlobalValue*> &Names,
                       SmallPtrSet<const GlobalValue*, 16> &MangledGlobals) {
  if (!GV->hasName())   // We must mangle unnamed globals.
    return;

  // Figure out if this is already used.
  GlobalValue *&ExistingValue = Names[GV->getNameStart()];
  if (!ExistingValue) {
    ExistingValue = GV;
    return;
  }

  // If GV is external but the existing one is static, mangle the existing one
  if ((GV->hasExternalLinkage() || GV->hasDLLImportLinkage()) &&
      !(ExistingValue->hasExternalLinkage()
        || ExistingValue->hasDLLImportLinkage())) {
    MangledGlobals.insert(ExistingValue);
    ExistingValue = GV;
  } else if ((GV->hasExternalLinkage() ||
              GV->hasDLLImportLinkage()) &&
             (ExistingValue->hasExternalLinkage() ||
              ExistingValue->hasDLLImportLinkage()) &&
             GV->isDeclaration() &&
             ExistingValue->isDeclaration()) {
    // If the two globals both have external inkage, and are both external,
    // don't mangle either of them, we just have some silly type mismatch.
  } else {
    // Otherwise, mangle GV
    MangledGlobals.insert(GV);
  }
}


Mangler::Mangler(Module &M, const char *prefix)
  : Prefix(prefix), UseQuotes(false), PreserveAsmNames(false),
    Count(0), TypeCounter(0) {
  std::fill(AcceptableChars, array_endof(AcceptableChars), 0);

  // Letters and numbers are acceptable.
  for (unsigned char X = 'a'; X <= 'z'; ++X)
    markCharAcceptable(X);
  for (unsigned char X = 'A'; X <= 'Z'; ++X)
    markCharAcceptable(X);
  for (unsigned char X = '0'; X <= '9'; ++X)
    markCharAcceptable(X);
  
  // These chars are acceptable.
  markCharAcceptable('_');
  markCharAcceptable('$');
  markCharAcceptable('.');
    
  // Calculate which global values have names that will collide when we throw
  // away type information.
  StringMap<GlobalValue*> Names;
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
    InsertName(I, Names, MangledGlobals);
  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I)
    InsertName(I, Names, MangledGlobals);
}