1//===- NameAnonFunctions.cpp - ThinLTO Summary-based Function Import ------===//
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// This file implements naming anonymous function to make sure they can be
11// refered to by ThinLTO.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/ADT/SmallString.h"
16#include "llvm/IR/Module.h"
17#include "llvm/Support/MD5.h"
18#include "llvm/Transforms/Utils/ModuleUtils.h"
19
20using namespace llvm;
21
22// Compute a "unique" hash for the module based on the name of the public
23// functions.
24class ModuleHasher {
25  Module &TheModule;
26  std::string TheHash;
27
28public:
29  ModuleHasher(Module &M) : TheModule(M) {}
30
31  /// Return the lazily computed hash.
32  std::string &get() {
33    if (!TheHash.empty())
34      // Cache hit :)
35      return TheHash;
36
37    MD5 Hasher;
38    for (auto &F : TheModule) {
39      if (F.isDeclaration() || F.hasLocalLinkage() || !F.hasName())
40        continue;
41      auto Name = F.getName();
42      Hasher.update(Name);
43    }
44    for (auto &GV : TheModule.globals()) {
45      if (GV.isDeclaration() || GV.hasLocalLinkage() || !GV.hasName())
46        continue;
47      auto Name = GV.getName();
48      Hasher.update(Name);
49    }
50
51    // Now return the result.
52    MD5::MD5Result Hash;
53    Hasher.final(Hash);
54    SmallString<32> Result;
55    MD5::stringifyResult(Hash, Result);
56    TheHash = Result.str();
57    return TheHash;
58  }
59};
60
61// Rename all the anon functions in the module
62bool llvm::nameUnamedFunctions(Module &M) {
63  bool Changed = false;
64  ModuleHasher ModuleHash(M);
65  int count = 0;
66  for (auto &F : M) {
67    if (F.hasName())
68      continue;
69    F.setName(Twine("anon.") + ModuleHash.get() + "." + Twine(count++));
70    Changed = true;
71  }
72  return Changed;
73}
74
75namespace {
76
77// Simple pass that provides a name to every anon function.
78class NameAnonFunction : public ModulePass {
79
80public:
81  /// Pass identification, replacement for typeid
82  static char ID;
83
84  /// Specify pass name for debug output
85  const char *getPassName() const override { return "Name Anon Functions"; }
86
87  explicit NameAnonFunction() : ModulePass(ID) {}
88
89  bool runOnModule(Module &M) override { return nameUnamedFunctions(M); }
90};
91char NameAnonFunction::ID = 0;
92
93} // anonymous namespace
94
95INITIALIZE_PASS_BEGIN(NameAnonFunction, "name-anon-functions",
96                      "Provide a name to nameless functions", false, false)
97INITIALIZE_PASS_END(NameAnonFunction, "name-anon-functions",
98                    "Provide a name to nameless functions", false, false)
99
100namespace llvm {
101ModulePass *createNameAnonFunctionPass() { return new NameAnonFunction(); }
102}
103