| 1 | //===- NameAnonGlobals.cpp - ThinLTO Support: Name Unnamed Globals --------===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | // |
| 9 | // This file implements naming anonymous globals to make sure they can be |
| 10 | // referred to by ThinLTO. |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
| 14 | #include "llvm/Transforms/Utils/NameAnonGlobals.h" |
| 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 | |
| 20 | using namespace llvm; |
| 21 | |
| 22 | namespace { |
| 23 | // Compute a "unique" hash for the module based on the name of the public |
| 24 | // globals. |
| 25 | class ModuleHasher { |
| 26 | Module &TheModule; |
| 27 | std::string TheHash; |
| 28 | |
| 29 | public: |
| 30 | ModuleHasher(Module &M) : TheModule(M) {} |
| 31 | |
| 32 | /// Return the lazily computed hash. |
| 33 | std::string &get() { |
| 34 | if (!TheHash.empty()) |
| 35 | // Cache hit :) |
| 36 | return TheHash; |
| 37 | |
| 38 | MD5 Hasher; |
| 39 | for (auto &F : TheModule) { |
| 40 | if (F.isDeclaration() || F.hasLocalLinkage() || !F.hasName()) |
| 41 | continue; |
| 42 | auto Name = F.getName(); |
| 43 | Hasher.update(Str: Name); |
| 44 | } |
| 45 | for (auto &GV : TheModule.globals()) { |
| 46 | if (GV.isDeclaration() || GV.hasLocalLinkage() || !GV.hasName()) |
| 47 | continue; |
| 48 | auto Name = GV.getName(); |
| 49 | Hasher.update(Str: Name); |
| 50 | } |
| 51 | |
| 52 | // Now return the result. |
| 53 | MD5::MD5Result Hash; |
| 54 | Hasher.final(Result&: Hash); |
| 55 | SmallString<32> Result; |
| 56 | MD5::stringifyResult(Result&: Hash, Str&: Result); |
| 57 | TheHash = std::string(Result); |
| 58 | return TheHash; |
| 59 | } |
| 60 | }; |
| 61 | } // end anonymous namespace |
| 62 | |
| 63 | // Rename all the anon globals in the module |
| 64 | bool llvm::nameUnamedGlobals(Module &M) { |
| 65 | bool Changed = false; |
| 66 | ModuleHasher ModuleHash(M); |
| 67 | int count = 0; |
| 68 | auto RenameIfNeed = [&](GlobalValue &GV) { |
| 69 | if (GV.hasName()) |
| 70 | return; |
| 71 | GV.setName(Twine("anon.") + ModuleHash.get() + "."+ Twine(count++)); |
| 72 | Changed = true; |
| 73 | }; |
| 74 | for (auto &GO : M.global_objects()) |
| 75 | RenameIfNeed(GO); |
| 76 | for (auto &GA : M.aliases()) |
| 77 | RenameIfNeed(GA); |
| 78 | |
| 79 | return Changed; |
| 80 | } |
| 81 | |
| 82 | PreservedAnalyses NameAnonGlobalPass::run(Module &M, |
| 83 | ModuleAnalysisManager &AM) { |
| 84 | if (!nameUnamedGlobals(M)) |
| 85 | return PreservedAnalyses::all(); |
| 86 | |
| 87 | return PreservedAnalyses::none(); |
| 88 | } |
| 89 |