llvm-project/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/System/Atomic.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,
                                    const char *PrivatePrefix) {
  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) {
    std::string Result;

    // If X does not start with (char)1, add the prefix.
    bool NeedPrefix = true;
    std::string::const_iterator I = X.begin();
    if (*I == 1) {
      NeedPrefix = false;
      ++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;
    }

    if (NeedPrefix) {
      if (Prefix)
        Result = Prefix + Result;
      if (PrivatePrefix)
        Result = PrivatePrefix + Result;
    }
    return Result;
  }

  bool NeedPrefix = true;
  bool NeedQuotes = false;
  std::string Result;    
  std::string::const_iterator I = X.begin();
  if (*I == 1) {
    NeedPrefix = false;
    ++I;  // Skip over the marker.
  }

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

  if (NeedPrefix) {
    if (Prefix)
      Result = Prefix + X;
    else
      Result = X;
    if (PrivatePrefix)
      Result = PrivatePrefix + Result;
  }
  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 uint32_t GlobalID = 0;
    
    unsigned OldID = GlobalID;
    sys::AtomicIncrement(&GlobalID);
    
    Name = "__unnamed_" + utostr(TypeUniqueID) + "_" + utostr(OldID);
  } else {
    if (GV->hasPrivateLinkage())
      Name = makeNameProper(GV->getName() + Suffix, Prefix, PrivatePrefix);
    else
      Name = makeNameProper(GV->getName() + Suffix, Prefix);
  }

  return Name;
}

Mangler::Mangler(Module &M, const char *prefix, const char *privatePrefix)
  : Prefix(prefix), PrivatePrefix (privatePrefix), 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('.');
}