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      1 //===-- Mangler.cpp - Self-contained c/asm llvm name mangler --------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // Unified name mangler for assembly backends.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "llvm/IR/Mangler.h"
     15 #include "llvm/ADT/SmallString.h"
     16 #include "llvm/ADT/Twine.h"
     17 #include "llvm/IR/DataLayout.h"
     18 #include "llvm/IR/DerivedTypes.h"
     19 #include "llvm/IR/Function.h"
     20 #include "llvm/Support/raw_ostream.h"
     21 using namespace llvm;
     22 
     23 static void getNameWithPrefixx(raw_ostream &OS, const Twine &GVName,
     24                               Mangler::ManglerPrefixTy PrefixTy,
     25                               const DataLayout &DL, bool UseAt) {
     26   SmallString<256> TmpData;
     27   StringRef Name = GVName.toStringRef(TmpData);
     28   assert(!Name.empty() && "getNameWithPrefix requires non-empty name");
     29 
     30   if (PrefixTy == Mangler::Private)
     31     OS << DL.getPrivateGlobalPrefix();
     32   else if (PrefixTy == Mangler::LinkerPrivate)
     33     OS << DL.getLinkerPrivateGlobalPrefix();
     34 
     35   if (UseAt) {
     36     OS << '@';
     37   } else {
     38     char Prefix = DL.getGlobalPrefix();
     39     if (Prefix != '\0')
     40       OS << Prefix;
     41   }
     42 
     43   // If this is a simple string that doesn't need escaping, just append it.
     44   OS << Name;
     45 }
     46 
     47 void Mangler::getNameWithPrefix(raw_ostream &OS, const Twine &GVName,
     48                                 ManglerPrefixTy PrefixTy) const {
     49   return getNameWithPrefixx(OS, GVName, PrefixTy, *DL, false);
     50 }
     51 
     52 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
     53                                 const Twine &GVName,
     54                                 ManglerPrefixTy PrefixTy) const {
     55   raw_svector_ostream OS(OutName);
     56   return getNameWithPrefix(OS, GVName, PrefixTy);
     57 }
     58 
     59 /// AddFastCallStdCallSuffix - Microsoft fastcall and stdcall functions require
     60 /// a suffix on their name indicating the number of words of arguments they
     61 /// take.
     62 static void AddFastCallStdCallSuffix(raw_ostream &OS, const Function *F,
     63                                      const DataLayout &TD) {
     64   // Calculate arguments size total.
     65   unsigned ArgWords = 0;
     66   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
     67        AI != AE; ++AI) {
     68     Type *Ty = AI->getType();
     69     // 'Dereference' type in case of byval or inalloca parameter attribute.
     70     if (AI->hasByValOrInAllocaAttr())
     71       Ty = cast<PointerType>(Ty)->getElementType();
     72     // Size should be aligned to DWORD boundary
     73     ArgWords += ((TD.getTypeAllocSize(Ty) + 3)/4)*4;
     74   }
     75 
     76   OS << '@' << ArgWords;
     77 }
     78 
     79 void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV,
     80                                 bool CannotUsePrivateLabel) const {
     81   ManglerPrefixTy PrefixTy = Mangler::Default;
     82   if (GV->hasPrivateLinkage()) {
     83     if (CannotUsePrivateLabel)
     84       PrefixTy = Mangler::LinkerPrivate;
     85     else
     86       PrefixTy = Mangler::Private;
     87   }
     88 
     89   if (!GV->hasName()) {
     90     // Get the ID for the global, assigning a new one if we haven't got one
     91     // already.
     92     unsigned &ID = AnonGlobalIDs[GV];
     93     if (ID == 0)
     94       ID = NextAnonGlobalID++;
     95 
     96     // Must mangle the global into a unique ID.
     97     getNameWithPrefix(OS, "__unnamed_" + Twine(ID), PrefixTy);
     98     return;
     99   }
    100 
    101   StringRef Name = GV->getName();
    102 
    103   // No need to do anything special if the global has the special "do not
    104   // mangle" flag in the name.
    105   if (Name[0] == '\1') {
    106     OS << Name.substr(1);
    107     return;
    108   }
    109 
    110   bool UseAt = false;
    111   const Function *MSFunc = nullptr;
    112   CallingConv::ID CC;
    113   if (DL->hasMicrosoftFastStdCallMangling()) {
    114     if ((MSFunc = dyn_cast<Function>(GV))) {
    115       CC = MSFunc->getCallingConv();
    116       // fastcall functions need to start with @ instead of _.
    117       if (CC == CallingConv::X86_FastCall)
    118         UseAt = true;
    119     }
    120   }
    121 
    122   getNameWithPrefixx(OS, Name, PrefixTy, *DL, UseAt);
    123 
    124   if (!MSFunc)
    125     return;
    126 
    127   // If we are supposed to add a microsoft-style suffix for stdcall/fastcall,
    128   // add it.
    129   // fastcall and stdcall functions usually need @42 at the end to specify
    130   // the argument info.
    131   FunctionType *FT = MSFunc->getFunctionType();
    132   if ((CC == CallingConv::X86_FastCall || CC == CallingConv::X86_StdCall) &&
    133       // "Pure" variadic functions do not receive @0 suffix.
    134       (!FT->isVarArg() || FT->getNumParams() == 0 ||
    135        (FT->getNumParams() == 1 && MSFunc->hasStructRetAttr())))
    136     AddFastCallStdCallSuffix(OS, MSFunc, *DL);
    137 }
    138 
    139 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
    140                                 const GlobalValue *GV,
    141                                 bool CannotUsePrivateLabel) const {
    142   raw_svector_ostream OS(OutName);
    143   getNameWithPrefix(OS, GV, CannotUsePrivateLabel);
    144 }
    145