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"
21using namespace llvm;
22
23static 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
47void Mangler::getNameWithPrefix(raw_ostream &OS, const Twine &GVName,
48                                ManglerPrefixTy PrefixTy) const {
49  return getNameWithPrefixx(OS, GVName, PrefixTy, *DL, false);
50}
51
52void 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.
62static 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
79void 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
139void 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