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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, char Prefix) {
     26   SmallString<256> TmpData;
     27   StringRef Name = GVName.toStringRef(TmpData);
     28   assert(!Name.empty() && "getNameWithPrefix requires non-empty name");
     29 
     30   // No need to do anything special if the global has the special "do not
     31   // mangle" flag in the name.
     32   if (Name[0] == '\1') {
     33     OS << Name.substr(1);
     34     return;
     35   }
     36 
     37   if (PrefixTy == Mangler::Private)
     38     OS << DL.getPrivateGlobalPrefix();
     39   else if (PrefixTy == Mangler::LinkerPrivate)
     40     OS << DL.getLinkerPrivateGlobalPrefix();
     41 
     42   if (Prefix != '\0')
     43     OS << Prefix;
     44 
     45   // If this is a simple string that doesn't need escaping, just append it.
     46   OS << Name;
     47 }
     48 
     49 void Mangler::getNameWithPrefix(raw_ostream &OS, const Twine &GVName,
     50                                 ManglerPrefixTy PrefixTy) const {
     51   char Prefix = DL->getGlobalPrefix();
     52   return getNameWithPrefixx(OS, GVName, PrefixTy, *DL, Prefix);
     53 }
     54 
     55 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
     56                                 const Twine &GVName,
     57                                 ManglerPrefixTy PrefixTy) const {
     58   raw_svector_ostream OS(OutName);
     59   return getNameWithPrefix(OS, GVName, PrefixTy);
     60 }
     61 
     62 static bool hasByteCountSuffix(CallingConv::ID CC) {
     63   switch (CC) {
     64   case CallingConv::X86_FastCall:
     65   case CallingConv::X86_StdCall:
     66   case CallingConv::X86_VectorCall:
     67     return true;
     68   default:
     69     return false;
     70   }
     71 }
     72 
     73 /// Microsoft fastcall and stdcall functions require a suffix on their name
     74 /// indicating the number of words of arguments they take.
     75 static void addByteCountSuffix(raw_ostream &OS, const Function *F,
     76                                const DataLayout &DL) {
     77   // Calculate arguments size total.
     78   unsigned ArgWords = 0;
     79   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
     80        AI != AE; ++AI) {
     81     Type *Ty = AI->getType();
     82     // 'Dereference' type in case of byval or inalloca parameter attribute.
     83     if (AI->hasByValOrInAllocaAttr())
     84       Ty = cast<PointerType>(Ty)->getElementType();
     85     // Size should be aligned to pointer size.
     86     unsigned PtrSize = DL.getPointerSize();
     87     ArgWords += RoundUpToAlignment(DL.getTypeAllocSize(Ty), PtrSize);
     88   }
     89 
     90   OS << '@' << ArgWords;
     91 }
     92 
     93 void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV,
     94                                 bool CannotUsePrivateLabel) const {
     95   ManglerPrefixTy PrefixTy = Mangler::Default;
     96   if (GV->hasPrivateLinkage()) {
     97     if (CannotUsePrivateLabel)
     98       PrefixTy = Mangler::LinkerPrivate;
     99     else
    100       PrefixTy = Mangler::Private;
    101   }
    102 
    103   if (!GV->hasName()) {
    104     // Get the ID for the global, assigning a new one if we haven't got one
    105     // already.
    106     unsigned &ID = AnonGlobalIDs[GV];
    107     if (ID == 0)
    108       ID = NextAnonGlobalID++;
    109 
    110     // Must mangle the global into a unique ID.
    111     getNameWithPrefix(OS, "__unnamed_" + Twine(ID), PrefixTy);
    112     return;
    113   }
    114 
    115   StringRef Name = GV->getName();
    116   char Prefix = DL->getGlobalPrefix();
    117 
    118   // Mangle functions with Microsoft calling conventions specially.  Only do
    119   // this mangling for x86_64 vectorcall and 32-bit x86.
    120   const Function *MSFunc = dyn_cast<Function>(GV);
    121   if (Name.startswith("\01"))
    122     MSFunc = nullptr; // Don't mangle when \01 is present.
    123   CallingConv::ID CC =
    124       MSFunc ? MSFunc->getCallingConv() : (unsigned)CallingConv::C;
    125   if (!DL->hasMicrosoftFastStdCallMangling() &&
    126       CC != CallingConv::X86_VectorCall)
    127     MSFunc = nullptr;
    128   if (MSFunc) {
    129     if (CC == CallingConv::X86_FastCall)
    130       Prefix = '@'; // fastcall functions have an @ prefix instead of _.
    131     else if (CC == CallingConv::X86_VectorCall)
    132       Prefix = '\0'; // vectorcall functions have no prefix.
    133   }
    134 
    135   getNameWithPrefixx(OS, Name, PrefixTy, *DL, Prefix);
    136 
    137   if (!MSFunc)
    138     return;
    139 
    140   // If we are supposed to add a microsoft-style suffix for stdcall, fastcall,
    141   // or vectorcall, add it.  These functions have a suffix of @N where N is the
    142   // cumulative byte size of all of the parameters to the function in decimal.
    143   if (CC == CallingConv::X86_VectorCall)
    144     OS << '@'; // vectorcall functions use a double @ suffix.
    145   FunctionType *FT = MSFunc->getFunctionType();
    146   if (hasByteCountSuffix(CC) &&
    147       // "Pure" variadic functions do not receive @0 suffix.
    148       (!FT->isVarArg() || FT->getNumParams() == 0 ||
    149        (FT->getNumParams() == 1 && MSFunc->hasStructRetAttr())))
    150     addByteCountSuffix(OS, MSFunc, *DL);
    151 }
    152 
    153 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
    154                                 const GlobalValue *GV,
    155                                 bool CannotUsePrivateLabel) const {
    156   raw_svector_ostream OS(OutName);
    157   getNameWithPrefix(OS, GV, CannotUsePrivateLabel);
    158 }
    159