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llvm-project/llvm/lib/Transforms/Utils/SymbolRewriter.cpp

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//===- SymbolRewriter.cpp - Symbol Rewriter -------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// SymbolRewriter is a LLVM pass which can rewrite symbols transparently within
// existing code. It is implemented as a compiler pass and is configured via a
// YAML configuration file.
//
// The YAML configuration file format is as follows:
//
// RewriteMapFile := RewriteDescriptors
// RewriteDescriptors := RewriteDescriptor | RewriteDescriptors
// RewriteDescriptor := RewriteDescriptorType ':' '{' RewriteDescriptorFields '}'
// RewriteDescriptorFields := RewriteDescriptorField | RewriteDescriptorFields
// RewriteDescriptorField := FieldIdentifier ':' FieldValue ','
// RewriteDescriptorType := Identifier
// FieldIdentifier := Identifier
// FieldValue := Identifier
// Identifier := [0-9a-zA-Z]+
//
// Currently, the following descriptor types are supported:
//
// - function: (function rewriting)
// + Source (original name of the function)
// + Target (explicit transformation)
// + Transform (pattern transformation)
// + Naked (boolean, whether the function is undecorated)
// - global variable: (external linkage global variable rewriting)
// + Source (original name of externally visible variable)
// + Target (explicit transformation)
// + Transform (pattern transformation)
// - global alias: (global alias rewriting)
// + Source (original name of the aliased name)
// + Target (explicit transformation)
// + Transform (pattern transformation)
//
// Note that source and exactly one of [Target, Transform] must be provided
//
// New rewrite descriptors can be created. Addding a new rewrite descriptor
// involves:
//
// a) extended the rewrite descriptor kind enumeration
// (<anonymous>::RewriteDescriptor::RewriteDescriptorType)
// b) implementing the new descriptor
// (c.f. <anonymous>::ExplicitRewriteFunctionDescriptor)
// c) extending the rewrite map parser
// (<anonymous>::RewriteMapParser::parseEntry)
//
// Specify to rewrite the symbols using the `-rewrite-symbols` option, and
// specify the map file to use for the rewriting via the `-rewrite-map-file`
// option.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/SymbolRewriter.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/ilist.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/IR/Comdat.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalObject.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Value.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Regex.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/YAMLParser.h"
#include <memory>
#include <string>
#include <vector>
using namespace llvm;
using namespace SymbolRewriter;
#define DEBUG_TYPE "symbol-rewriter"
static cl::list<std::string> RewriteMapFiles("rewrite-map-file",
cl::desc("Symbol Rewrite Map"),
cl::value_desc("filename"),
cl::Hidden);
static void rewriteComdat(Module &M, GlobalObject *GO,
const std::string &Source,
const std::string &Target) {
if (Comdat *CD = GO->getComdat()) {
auto &Comdats = M.getComdatSymbolTable();
Comdat *C = M.getOrInsertComdat(Target);
C->setSelectionKind(CD->getSelectionKind());
GO->setComdat(C);
Comdats.erase(Comdats.find(Source));
}
}
namespace {
template <RewriteDescriptor::Type DT, typename ValueType,
ValueType *(Module::*Get)(StringRef) const>
class ExplicitRewriteDescriptor : public RewriteDescriptor {
public:
const std::string Source;
const std::string Target;
ExplicitRewriteDescriptor(StringRef S, StringRef T, const bool Naked)
: RewriteDescriptor(DT),
Source(std::string(Naked ? StringRef("\01" + S.str()) : S)),
Target(std::string(T)) {}
bool performOnModule(Module &M) override;
static bool classof(const RewriteDescriptor *RD) {
return RD->getType() == DT;
}
};
} // end anonymous namespace
template <RewriteDescriptor::Type DT, typename ValueType,
ValueType *(Module::*Get)(StringRef) const>
bool ExplicitRewriteDescriptor<DT, ValueType, Get>::performOnModule(Module &M) {
bool Changed = false;
if (ValueType *S = (M.*Get)(Source)) {
if (GlobalObject *GO = dyn_cast<GlobalObject>(S))
rewriteComdat(M, GO, Source, Target);
if (Value *T = (M.*Get)(Target))
S->setValueName(T->getValueName());
else
S->setName(Target);
Changed = true;
}
return Changed;
}
namespace {
template <RewriteDescriptor::Type DT, typename ValueType,
ValueType *(Module::*Get)(StringRef) const,
iterator_range<typename iplist<ValueType>::iterator>
(Module::*Iterator)()>
class PatternRewriteDescriptor : public RewriteDescriptor {
public:
const std::string Pattern;
const std::string Transform;
PatternRewriteDescriptor(StringRef P, StringRef T)
: RewriteDescriptor(DT), Pattern(std::string(P)),
Transform(std::string(T)) {}
bool performOnModule(Module &M) override;
static bool classof(const RewriteDescriptor *RD) {
return RD->getType() == DT;
}
};
} // end anonymous namespace
template <RewriteDescriptor::Type DT, typename ValueType,
ValueType *(Module::*Get)(StringRef) const,
iterator_range<typename iplist<ValueType>::iterator>
(Module::*Iterator)()>
bool PatternRewriteDescriptor<DT, ValueType, Get, Iterator>::
performOnModule(Module &M) {
bool Changed = false;
for (auto &C : (M.*Iterator)()) {
std::string Error;
std::string Name = Regex(Pattern).sub(Transform, C.getName(), &Error);
if (!Error.empty())
report_fatal_error("unable to transforn " + C.getName() + " in " +
M.getModuleIdentifier() + ": " + Error);
if (C.getName() == Name)
continue;
if (GlobalObject *GO = dyn_cast<GlobalObject>(&C))
rewriteComdat(M, GO, std::string(C.getName()), Name);
if (Value *V = (M.*Get)(Name))
C.setValueName(V->getValueName());
else
C.setName(Name);
Changed = true;
}
return Changed;
}
namespace {
/// Represents a rewrite for an explicitly named (function) symbol. Both the
/// source function name and target function name of the transformation are
/// explicitly spelt out.
using ExplicitRewriteFunctionDescriptor =
ExplicitRewriteDescriptor<RewriteDescriptor::Type::Function, Function,
&Module::getFunction>;
/// Represents a rewrite for an explicitly named (global variable) symbol. Both
/// the source variable name and target variable name are spelt out. This
/// applies only to module level variables.
using ExplicitRewriteGlobalVariableDescriptor =
ExplicitRewriteDescriptor<RewriteDescriptor::Type::GlobalVariable,
GlobalVariable, &Module::getGlobalVariable>;
/// Represents a rewrite for an explicitly named global alias. Both the source
/// and target name are explicitly spelt out.
using ExplicitRewriteNamedAliasDescriptor =
ExplicitRewriteDescriptor<RewriteDescriptor::Type::NamedAlias, GlobalAlias,
&Module::getNamedAlias>;
/// Represents a rewrite for a regular expression based pattern for functions.
/// A pattern for the function name is provided and a transformation for that
/// pattern to determine the target function name create the rewrite rule.
using PatternRewriteFunctionDescriptor =
PatternRewriteDescriptor<RewriteDescriptor::Type::Function, Function,
&Module::getFunction, &Module::functions>;
/// Represents a rewrite for a global variable based upon a matching pattern.
/// Each global variable matching the provided pattern will be transformed as
/// described in the transformation pattern for the target. Applies only to
/// module level variables.
using PatternRewriteGlobalVariableDescriptor =
PatternRewriteDescriptor<RewriteDescriptor::Type::GlobalVariable,
GlobalVariable, &Module::getGlobalVariable,
&Module::globals>;
/// PatternRewriteNamedAliasDescriptor - represents a rewrite for global
/// aliases which match a given pattern. The provided transformation will be
/// applied to each of the matching names.
using PatternRewriteNamedAliasDescriptor =
PatternRewriteDescriptor<RewriteDescriptor::Type::NamedAlias, GlobalAlias,
&Module::getNamedAlias, &Module::aliases>;
} // end anonymous namespace
bool RewriteMapParser::parse(const std::string &MapFile,
RewriteDescriptorList *DL) {
ErrorOr<std::unique_ptr<MemoryBuffer>> Mapping =
MemoryBuffer::getFile(MapFile);
if (!Mapping)
report_fatal_error("unable to read rewrite map '" + MapFile + "': " +
Mapping.getError().message());
if (!parse(*Mapping, DL))
report_fatal_error("unable to parse rewrite map '" + MapFile + "'");
return true;
}
bool RewriteMapParser::parse(std::unique_ptr<MemoryBuffer> &MapFile,
RewriteDescriptorList *DL) {
SourceMgr SM;
yaml::Stream YS(MapFile->getBuffer(), SM);
for (auto &Document : YS) {
yaml::MappingNode *DescriptorList;
// ignore empty documents
if (isa<yaml::NullNode>(Document.getRoot()))
continue;
DescriptorList = dyn_cast<yaml::MappingNode>(Document.getRoot());
if (!DescriptorList) {
YS.printError(Document.getRoot(), "DescriptorList node must be a map");
return false;
}
for (auto &Descriptor : *DescriptorList)
if (!parseEntry(YS, Descriptor, DL))
return false;
}
return true;
}
bool RewriteMapParser::parseEntry(yaml::Stream &YS, yaml::KeyValueNode &Entry,
RewriteDescriptorList *DL) {
yaml::ScalarNode *Key;
yaml::MappingNode *Value;
SmallString<32> KeyStorage;
StringRef RewriteType;
Key = dyn_cast<yaml::ScalarNode>(Entry.getKey());
if (!Key) {
YS.printError(Entry.getKey(), "rewrite type must be a scalar");
return false;
}
Value = dyn_cast<yaml::MappingNode>(Entry.getValue());
if (!Value) {
YS.printError(Entry.getValue(), "rewrite descriptor must be a map");
return false;
}
RewriteType = Key->getValue(KeyStorage);
if (RewriteType.equals("function"))
return parseRewriteFunctionDescriptor(YS, Key, Value, DL);
else if (RewriteType.equals("global variable"))
return parseRewriteGlobalVariableDescriptor(YS, Key, Value, DL);
else if (RewriteType.equals("global alias"))
return parseRewriteGlobalAliasDescriptor(YS, Key, Value, DL);
YS.printError(Entry.getKey(), "unknown rewrite type");
return false;
}
bool RewriteMapParser::
parseRewriteFunctionDescriptor(yaml::Stream &YS, yaml::ScalarNode *K,
yaml::MappingNode *Descriptor,
RewriteDescriptorList *DL) {
bool Naked = false;
std::string Source;
std::string Target;
std::string Transform;
for (auto &Field : *Descriptor) {
yaml::ScalarNode *Key;
yaml::ScalarNode *Value;
SmallString<32> KeyStorage;
SmallString<32> ValueStorage;
StringRef KeyValue;
Key = dyn_cast<yaml::ScalarNode>(Field.getKey());
if (!Key) {
YS.printError(Field.getKey(), "descriptor key must be a scalar");
return false;
}
Value = dyn_cast<yaml::ScalarNode>(Field.getValue());
if (!Value) {
YS.printError(Field.getValue(), "descriptor value must be a scalar");
return false;
}
KeyValue = Key->getValue(KeyStorage);
if (KeyValue.equals("source")) {
std::string Error;
Source = std::string(Value->getValue(ValueStorage));
if (!Regex(Source).isValid(Error)) {
YS.printError(Field.getKey(), "invalid regex: " + Error);
return false;
}
} else if (KeyValue.equals("target")) {
Target = std::string(Value->getValue(ValueStorage));
} else if (KeyValue.equals("transform")) {
Transform = std::string(Value->getValue(ValueStorage));
} else if (KeyValue.equals("naked")) {
std::string Undecorated;
Undecorated = std::string(Value->getValue(ValueStorage));
Naked = StringRef(Undecorated).lower() == "true" || Undecorated == "1";
} else {
YS.printError(Field.getKey(), "unknown key for function");
return false;
}
}
if (Transform.empty() == Target.empty()) {
YS.printError(Descriptor,
"exactly one of transform or target must be specified");
return false;
}
// TODO see if there is a more elegant solution to selecting the rewrite
// descriptor type
if (!Target.empty())
DL->push_back(std::make_unique<ExplicitRewriteFunctionDescriptor>(
Source, Target, Naked));
else
DL->push_back(
std::make_unique<PatternRewriteFunctionDescriptor>(Source, Transform));
return true;
}
bool RewriteMapParser::
parseRewriteGlobalVariableDescriptor(yaml::Stream &YS, yaml::ScalarNode *K,
yaml::MappingNode *Descriptor,
RewriteDescriptorList *DL) {
std::string Source;
std::string Target;
std::string Transform;
for (auto &Field : *Descriptor) {
yaml::ScalarNode *Key;
yaml::ScalarNode *Value;
SmallString<32> KeyStorage;
SmallString<32> ValueStorage;
StringRef KeyValue;
Key = dyn_cast<yaml::ScalarNode>(Field.getKey());
if (!Key) {
YS.printError(Field.getKey(), "descriptor Key must be a scalar");
return false;
}
Value = dyn_cast<yaml::ScalarNode>(Field.getValue());
if (!Value) {
YS.printError(Field.getValue(), "descriptor value must be a scalar");
return false;
}
KeyValue = Key->getValue(KeyStorage);
if (KeyValue.equals("source")) {
std::string Error;
Source = std::string(Value->getValue(ValueStorage));
if (!Regex(Source).isValid(Error)) {
YS.printError(Field.getKey(), "invalid regex: " + Error);
return false;
}
} else if (KeyValue.equals("target")) {
Target = std::string(Value->getValue(ValueStorage));
} else if (KeyValue.equals("transform")) {
Transform = std::string(Value->getValue(ValueStorage));
} else {
YS.printError(Field.getKey(), "unknown Key for Global Variable");
return false;
}
}
if (Transform.empty() == Target.empty()) {
YS.printError(Descriptor,
"exactly one of transform or target must be specified");
return false;
}
if (!Target.empty())
DL->push_back(std::make_unique<ExplicitRewriteGlobalVariableDescriptor>(
Source, Target,
/*Naked*/ false));
else
DL->push_back(std::make_unique<PatternRewriteGlobalVariableDescriptor>(
Source, Transform));
return true;
}
bool RewriteMapParser::
parseRewriteGlobalAliasDescriptor(yaml::Stream &YS, yaml::ScalarNode *K,
yaml::MappingNode *Descriptor,
RewriteDescriptorList *DL) {
std::string Source;
std::string Target;
std::string Transform;
for (auto &Field : *Descriptor) {
yaml::ScalarNode *Key;
yaml::ScalarNode *Value;
SmallString<32> KeyStorage;
SmallString<32> ValueStorage;
StringRef KeyValue;
Key = dyn_cast<yaml::ScalarNode>(Field.getKey());
if (!Key) {
YS.printError(Field.getKey(), "descriptor key must be a scalar");
return false;
}
Value = dyn_cast<yaml::ScalarNode>(Field.getValue());
if (!Value) {
YS.printError(Field.getValue(), "descriptor value must be a scalar");
return false;
}
KeyValue = Key->getValue(KeyStorage);
if (KeyValue.equals("source")) {
std::string Error;
Source = std::string(Value->getValue(ValueStorage));
if (!Regex(Source).isValid(Error)) {
YS.printError(Field.getKey(), "invalid regex: " + Error);
return false;
}
} else if (KeyValue.equals("target")) {
Target = std::string(Value->getValue(ValueStorage));
} else if (KeyValue.equals("transform")) {
Transform = std::string(Value->getValue(ValueStorage));
} else {
YS.printError(Field.getKey(), "unknown key for Global Alias");
return false;
}
}
if (Transform.empty() == Target.empty()) {
YS.printError(Descriptor,
"exactly one of transform or target must be specified");
return false;
}
if (!Target.empty())
DL->push_back(std::make_unique<ExplicitRewriteNamedAliasDescriptor>(
Source, Target,
/*Naked*/ false));
else
DL->push_back(std::make_unique<PatternRewriteNamedAliasDescriptor>(
Source, Transform));
return true;
}
namespace {
class RewriteSymbolsLegacyPass : public ModulePass {
public:
static char ID; // Pass identification, replacement for typeid
RewriteSymbolsLegacyPass();
RewriteSymbolsLegacyPass(SymbolRewriter::RewriteDescriptorList &DL);
bool runOnModule(Module &M) override;
private:
RewriteSymbolPass Impl;
};
} // end anonymous namespace
char RewriteSymbolsLegacyPass::ID = 0;
RewriteSymbolsLegacyPass::RewriteSymbolsLegacyPass() : ModulePass(ID) {
initializeRewriteSymbolsLegacyPassPass(*PassRegistry::getPassRegistry());
}
RewriteSymbolsLegacyPass::RewriteSymbolsLegacyPass(
SymbolRewriter::RewriteDescriptorList &DL)
: ModulePass(ID), Impl(DL) {}
bool RewriteSymbolsLegacyPass::runOnModule(Module &M) {
return Impl.runImpl(M);
}
PreservedAnalyses RewriteSymbolPass::run(Module &M, ModuleAnalysisManager &AM) {
if (!runImpl(M))
return PreservedAnalyses::all();
return PreservedAnalyses::none();
}
bool RewriteSymbolPass::runImpl(Module &M) {
bool Changed;
Changed = false;
for (auto &Descriptor : Descriptors)
Changed |= Descriptor->performOnModule(M);
return Changed;
}
void RewriteSymbolPass::loadAndParseMapFiles() {
const std::vector<std::string> MapFiles(RewriteMapFiles);
SymbolRewriter::RewriteMapParser Parser;
for (const auto &MapFile : MapFiles)
Parser.parse(MapFile, &Descriptors);
}
INITIALIZE_PASS(RewriteSymbolsLegacyPass, "rewrite-symbols", "Rewrite Symbols",
false, false)
ModulePass *llvm::createRewriteSymbolsPass() {
return new RewriteSymbolsLegacyPass();
}
ModulePass *
llvm::createRewriteSymbolsPass(SymbolRewriter::RewriteDescriptorList &DL) {
return new RewriteSymbolsLegacyPass(DL);
}
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