llvm-capstone/llvm/lib/Transforms/Utils/NameAnonGlobals.cpp
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

121 lines
3.3 KiB
C++

//===- NameAnonGlobals.cpp - ThinLTO Support: Name Unnamed Globals --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements naming anonymous globals to make sure they can be
// referred to by ThinLTO.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/NameAnonGlobals.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/MD5.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
using namespace llvm;
namespace {
// Compute a "unique" hash for the module based on the name of the public
// globals.
class ModuleHasher {
Module &TheModule;
std::string TheHash;
public:
ModuleHasher(Module &M) : TheModule(M) {}
/// Return the lazily computed hash.
std::string &get() {
if (!TheHash.empty())
// Cache hit :)
return TheHash;
MD5 Hasher;
for (auto &F : TheModule) {
if (F.isDeclaration() || F.hasLocalLinkage() || !F.hasName())
continue;
auto Name = F.getName();
Hasher.update(Name);
}
for (auto &GV : TheModule.globals()) {
if (GV.isDeclaration() || GV.hasLocalLinkage() || !GV.hasName())
continue;
auto Name = GV.getName();
Hasher.update(Name);
}
// Now return the result.
MD5::MD5Result Hash;
Hasher.final(Hash);
SmallString<32> Result;
MD5::stringifyResult(Hash, Result);
TheHash = Result.str();
return TheHash;
}
};
} // end anonymous namespace
// Rename all the anon globals in the module
bool llvm::nameUnamedGlobals(Module &M) {
bool Changed = false;
ModuleHasher ModuleHash(M);
int count = 0;
auto RenameIfNeed = [&](GlobalValue &GV) {
if (GV.hasName())
return;
GV.setName(Twine("anon.") + ModuleHash.get() + "." + Twine(count++));
Changed = true;
};
for (auto &GO : M.global_objects())
RenameIfNeed(GO);
for (auto &GA : M.aliases())
RenameIfNeed(GA);
return Changed;
}
namespace {
// Legacy pass that provides a name to every anon globals.
class NameAnonGlobalLegacyPass : public ModulePass {
public:
/// Pass identification, replacement for typeid
static char ID;
/// Specify pass name for debug output
StringRef getPassName() const override { return "Name Anon Globals"; }
explicit NameAnonGlobalLegacyPass() : ModulePass(ID) {}
bool runOnModule(Module &M) override { return nameUnamedGlobals(M); }
};
char NameAnonGlobalLegacyPass::ID = 0;
} // anonymous namespace
PreservedAnalyses NameAnonGlobalPass::run(Module &M,
ModuleAnalysisManager &AM) {
if (!nameUnamedGlobals(M))
return PreservedAnalyses::all();
return PreservedAnalyses::none();
}
INITIALIZE_PASS_BEGIN(NameAnonGlobalLegacyPass, "name-anon-globals",
"Provide a name to nameless globals", false, false)
INITIALIZE_PASS_END(NameAnonGlobalLegacyPass, "name-anon-globals",
"Provide a name to nameless globals", false, false)
namespace llvm {
ModulePass *createNameAnonGlobalPass() {
return new NameAnonGlobalLegacyPass();
}
}