//===- SymbolRewriter.h - Symbol Rewriting Pass -----------------*- C++ -*-===//
//
// 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 provides the prototypes and definitions related to the Symbol
// Rewriter pass.
//
// The Symbol Rewriter pass takes a set of rewrite descriptors which define
// transformations for symbol names. These can be either single name to name
// trnsformation or more broad regular expression based transformations.
//
// All the functions are re-written at the IR level. The Symbol Rewriter itself
// is exposed as a module level pass. All symbols at the module level are
// iterated. For any matching symbol, the requested transformation is applied,
// updating references to it as well (a la RAUW). The resulting binary will
// only contain the rewritten symbols.
//
// By performing this operation in the compiler, we are able to catch symbols
// that would otherwise not be possible to catch (e.g. inlined symbols).
//
// This makes it possible to cleanly transform symbols without resorting to
// overly-complex macro tricks and the pre-processor. An example of where this
// is useful is the sanitizers where we would like to intercept a well-defined
// set of functions across the module.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H
#define LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H
#include "llvm/IR/PassManager.h"
#include <list>
#include <memory>
#include <string>
namespace llvm {
class MemoryBuffer;
class Module;
class ModulePass;
namespace yaml {
class KeyValueNode;
class MappingNode;
class ScalarNode;
class Stream;
} // end namespace yaml
namespace SymbolRewriter {
/// The basic entity representing a rewrite operation. It serves as the base
/// class for any rewrite descriptor. It has a certain set of specializations
/// which describe a particular rewrite.
///
/// The RewriteMapParser can be used to parse a mapping file that provides the
/// mapping for rewriting the symbols. The descriptors individually describe
/// whether to rewrite a function, global variable, or global alias. Each of
/// these can be selected either by explicitly providing a name for the ones to
/// be rewritten or providing a (posix compatible) regular expression that will
/// select the symbols to rewrite. This descriptor list is passed to the
/// SymbolRewriter pass.
class RewriteDescriptor {
public:
enum class Type {
Invalid, /// invalid
Function, /// function - descriptor rewrites a function
GlobalVariable, /// global variable - descriptor rewrites a global variable
NamedAlias, /// named alias - descriptor rewrites a global alias
};
RewriteDescriptor(const RewriteDescriptor &) = delete;
RewriteDescriptor &operator=(const RewriteDescriptor &) = delete;
virtual ~RewriteDescriptor() = default;
Type getType() const { return Kind; }
virtual bool performOnModule(Module &M) = 0;
protected:
explicit RewriteDescriptor(Type T) : Kind(T) {}
private:
const Type Kind;
};
using RewriteDescriptorList = std::list<std::unique_ptr<RewriteDescriptor>>;
class RewriteMapParser {
public:
bool parse(const std::string &MapFile, RewriteDescriptorList *Descriptors);
private:
bool parse(std::unique_ptr<MemoryBuffer> &MapFile, RewriteDescriptorList *DL);
bool parseEntry(yaml::Stream &Stream, yaml::KeyValueNode &Entry,
RewriteDescriptorList *DL);
bool parseRewriteFunctionDescriptor(yaml::Stream &Stream,
yaml::ScalarNode *Key,
yaml::MappingNode *Value,
RewriteDescriptorList *DL);
bool parseRewriteGlobalVariableDescriptor(yaml::Stream &Stream,
yaml::ScalarNode *Key,
yaml::MappingNode *Value,
RewriteDescriptorList *DL);
bool parseRewriteGlobalAliasDescriptor(yaml::Stream &YS, yaml::ScalarNode *K,
yaml::MappingNode *V,
RewriteDescriptorList *DL);
};
} // end namespace SymbolRewriter
ModulePass *createRewriteSymbolsPass();
ModulePass *createRewriteSymbolsPass(SymbolRewriter::RewriteDescriptorList &);
class RewriteSymbolPass : public PassInfoMixin<RewriteSymbolPass> {
public:
RewriteSymbolPass() { loadAndParseMapFiles(); }
RewriteSymbolPass(SymbolRewriter::RewriteDescriptorList &DL) {
Descriptors.splice(Descriptors.begin(), DL);
}
PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
// Glue for old PM
bool runImpl(Module &M);
private:
void loadAndParseMapFiles();
SymbolRewriter::RewriteDescriptorList Descriptors;
};
} // end namespace llvm
#endif // LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H