1 //===- SymbolRewriter.cpp - Symbol Rewriter ---------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // SymbolRewriter is a LLVM pass which can rewrite symbols transparently within
11 // existing code. It is implemented as a compiler pass and is configured via a
12 // YAML configuration file.
14 // The YAML configuration file format is as follows:
16 // RewriteMapFile := RewriteDescriptors
17 // RewriteDescriptors := RewriteDescriptor | RewriteDescriptors
18 // RewriteDescriptor := RewriteDescriptorType ':' '{' RewriteDescriptorFields '}'
19 // RewriteDescriptorFields := RewriteDescriptorField | RewriteDescriptorFields
20 // RewriteDescriptorField := FieldIdentifier ':' FieldValue ','
21 // RewriteDescriptorType := Identifier
22 // FieldIdentifier := Identifier
23 // FieldValue := Identifier
24 // Identifier := [0-9a-zA-Z]+
26 // Currently, the following descriptor types are supported:
28 // - function: (function rewriting)
29 // + Source (original name of the function)
30 // + Target (explicit transformation)
31 // + Transform (pattern transformation)
32 // + Naked (boolean, whether the function is undecorated)
33 // - global variable: (external linkage global variable rewriting)
34 // + Source (original name of externally visible variable)
35 // + Target (explicit transformation)
36 // + Transform (pattern transformation)
37 // - global alias: (global alias rewriting)
38 // + Source (original name of the aliased name)
39 // + Target (explicit transformation)
40 // + Transform (pattern transformation)
42 // Note that source and exactly one of [Target, Transform] must be provided
44 // New rewrite descriptors can be created. Addding a new rewrite descriptor
47 // a) extended the rewrite descriptor kind enumeration
48 // (<anonymous>::RewriteDescriptor::RewriteDescriptorType)
49 // b) implementing the new descriptor
50 // (c.f. <anonymous>::ExplicitRewriteFunctionDescriptor)
51 // c) extending the rewrite map parser
52 // (<anonymous>::RewriteMapParser::parseEntry)
54 // Specify to rewrite the symbols using the `-rewrite-symbols` option, and
55 // specify the map file to use for the rewriting via the `-rewrite-map-file`
58 //===----------------------------------------------------------------------===//
60 #define DEBUG_TYPE "symbol-rewriter"
61 #include "llvm/Transforms/Utils/SymbolRewriter.h"
62 #include "llvm/ADT/SmallString.h"
63 #include "llvm/IR/LegacyPassManager.h"
64 #include "llvm/Pass.h"
65 #include "llvm/Support/CommandLine.h"
66 #include "llvm/Support/Debug.h"
67 #include "llvm/Support/MemoryBuffer.h"
68 #include "llvm/Support/Regex.h"
69 #include "llvm/Support/SourceMgr.h"
70 #include "llvm/Support/YAMLParser.h"
71 #include "llvm/Support/raw_ostream.h"
74 using namespace SymbolRewriter;
76 static cl::list<std::string> RewriteMapFiles("rewrite-map-file",
77 cl::desc("Symbol Rewrite Map"),
78 cl::value_desc("filename"));
80 static void rewriteComdat(Module &M, GlobalObject *GO,
81 const std::string &Source,
82 const std::string &Target) {
83 if (Comdat *CD = GO->getComdat()) {
84 auto &Comdats = M.getComdatSymbolTable();
86 Comdat *C = M.getOrInsertComdat(Target);
87 C->setSelectionKind(CD->getSelectionKind());
90 Comdats.erase(Comdats.find(Source));
95 template <RewriteDescriptor::Type DT, typename ValueType,
96 ValueType *(llvm::Module::*Get)(StringRef) const>
97 class ExplicitRewriteDescriptor : public RewriteDescriptor {
99 const std::string Source;
100 const std::string Target;
102 ExplicitRewriteDescriptor(StringRef S, StringRef T, const bool Naked)
103 : RewriteDescriptor(DT), Source(Naked ? StringRef("\01" + S.str()) : S),
106 bool performOnModule(Module &M) override;
108 static bool classof(const RewriteDescriptor *RD) {
109 return RD->getType() == DT;
113 template <RewriteDescriptor::Type DT, typename ValueType,
114 ValueType *(llvm::Module::*Get)(StringRef) const>
115 bool ExplicitRewriteDescriptor<DT, ValueType, Get>::performOnModule(Module &M) {
116 bool Changed = false;
117 if (ValueType *S = (M.*Get)(Source)) {
118 if (GlobalObject *GO = dyn_cast<GlobalObject>(S))
119 rewriteComdat(M, GO, Source, Target);
121 if (Value *T = (M.*Get)(Target))
122 S->setValueName(T->getValueName());
131 template <RewriteDescriptor::Type DT, typename ValueType,
132 ValueType *(llvm::Module::*Get)(StringRef) const,
133 iterator_range<typename iplist<ValueType>::iterator>
134 (llvm::Module::*Iterator)()>
135 class PatternRewriteDescriptor : public RewriteDescriptor {
137 const std::string Pattern;
138 const std::string Transform;
140 PatternRewriteDescriptor(StringRef P, StringRef T)
141 : RewriteDescriptor(DT), Pattern(P), Transform(T) { }
143 bool performOnModule(Module &M) override;
145 static bool classof(const RewriteDescriptor *RD) {
146 return RD->getType() == DT;
150 template <RewriteDescriptor::Type DT, typename ValueType,
151 ValueType *(llvm::Module::*Get)(StringRef) const,
152 iterator_range<typename iplist<ValueType>::iterator>
153 (llvm::Module::*Iterator)()>
154 bool PatternRewriteDescriptor<DT, ValueType, Get, Iterator>::
155 performOnModule(Module &M) {
156 bool Changed = false;
157 for (auto &C : (M.*Iterator)()) {
160 std::string Name = Regex(Pattern).sub(Transform, C.getName(), &Error);
162 report_fatal_error("unable to transforn " + C.getName() + " in " +
163 M.getModuleIdentifier() + ": " + Error);
165 if (C.getName() == Name)
168 if (GlobalObject *GO = dyn_cast<GlobalObject>(&C))
169 rewriteComdat(M, GO, C.getName(), Name);
171 if (Value *V = (M.*Get)(Name))
172 C.setValueName(V->getValueName());
181 /// Represents a rewrite for an explicitly named (function) symbol. Both the
182 /// source function name and target function name of the transformation are
183 /// explicitly spelt out.
184 typedef ExplicitRewriteDescriptor<RewriteDescriptor::Type::Function,
185 llvm::Function, &llvm::Module::getFunction>
186 ExplicitRewriteFunctionDescriptor;
188 /// Represents a rewrite for an explicitly named (global variable) symbol. Both
189 /// the source variable name and target variable name are spelt out. This
190 /// applies only to module level variables.
191 typedef ExplicitRewriteDescriptor<RewriteDescriptor::Type::GlobalVariable,
192 llvm::GlobalVariable,
193 &llvm::Module::getGlobalVariable>
194 ExplicitRewriteGlobalVariableDescriptor;
196 /// Represents a rewrite for an explicitly named global alias. Both the source
197 /// and target name are explicitly spelt out.
198 typedef ExplicitRewriteDescriptor<RewriteDescriptor::Type::NamedAlias,
200 &llvm::Module::getNamedAlias>
201 ExplicitRewriteNamedAliasDescriptor;
203 /// Represents a rewrite for a regular expression based pattern for functions.
204 /// A pattern for the function name is provided and a transformation for that
205 /// pattern to determine the target function name create the rewrite rule.
206 typedef PatternRewriteDescriptor<RewriteDescriptor::Type::Function,
207 llvm::Function, &llvm::Module::getFunction,
208 &llvm::Module::functions>
209 PatternRewriteFunctionDescriptor;
211 /// Represents a rewrite for a global variable based upon a matching pattern.
212 /// Each global variable matching the provided pattern will be transformed as
213 /// described in the transformation pattern for the target. Applies only to
214 /// module level variables.
215 typedef PatternRewriteDescriptor<RewriteDescriptor::Type::GlobalVariable,
216 llvm::GlobalVariable,
217 &llvm::Module::getGlobalVariable,
218 &llvm::Module::globals>
219 PatternRewriteGlobalVariableDescriptor;
221 /// PatternRewriteNamedAliasDescriptor - represents a rewrite for global
222 /// aliases which match a given pattern. The provided transformation will be
223 /// applied to each of the matching names.
224 typedef PatternRewriteDescriptor<RewriteDescriptor::Type::NamedAlias,
226 &llvm::Module::getNamedAlias,
227 &llvm::Module::aliases>
228 PatternRewriteNamedAliasDescriptor;
231 bool RewriteMapParser::parse(const std::string &MapFile,
232 RewriteDescriptorList *DL) {
233 ErrorOr<std::unique_ptr<MemoryBuffer>> Mapping =
234 MemoryBuffer::getFile(MapFile);
237 report_fatal_error("unable to read rewrite map '" + MapFile + "': " +
238 Mapping.getError().message());
240 if (!parse(*Mapping, DL))
241 report_fatal_error("unable to parse rewrite map '" + MapFile + "'");
246 bool RewriteMapParser::parse(std::unique_ptr<MemoryBuffer> &MapFile,
247 RewriteDescriptorList *DL) {
249 yaml::Stream YS(MapFile->getBuffer(), SM);
251 for (auto &Document : YS) {
252 yaml::MappingNode *DescriptorList;
254 // ignore empty documents
255 if (isa<yaml::NullNode>(Document.getRoot()))
258 DescriptorList = dyn_cast<yaml::MappingNode>(Document.getRoot());
259 if (!DescriptorList) {
260 YS.printError(Document.getRoot(), "DescriptorList node must be a map");
264 for (auto &Descriptor : *DescriptorList)
265 if (!parseEntry(YS, Descriptor, DL))
272 bool RewriteMapParser::parseEntry(yaml::Stream &YS, yaml::KeyValueNode &Entry,
273 RewriteDescriptorList *DL) {
274 yaml::ScalarNode *Key;
275 yaml::MappingNode *Value;
276 SmallString<32> KeyStorage;
277 StringRef RewriteType;
279 Key = dyn_cast<yaml::ScalarNode>(Entry.getKey());
281 YS.printError(Entry.getKey(), "rewrite type must be a scalar");
285 Value = dyn_cast<yaml::MappingNode>(Entry.getValue());
287 YS.printError(Entry.getValue(), "rewrite descriptor must be a map");
291 RewriteType = Key->getValue(KeyStorage);
292 if (RewriteType.equals("function"))
293 return parseRewriteFunctionDescriptor(YS, Key, Value, DL);
294 else if (RewriteType.equals("global variable"))
295 return parseRewriteGlobalVariableDescriptor(YS, Key, Value, DL);
296 else if (RewriteType.equals("global alias"))
297 return parseRewriteGlobalAliasDescriptor(YS, Key, Value, DL);
299 YS.printError(Entry.getKey(), "unknown rewrite type");
303 bool RewriteMapParser::
304 parseRewriteFunctionDescriptor(yaml::Stream &YS, yaml::ScalarNode *K,
305 yaml::MappingNode *Descriptor,
306 RewriteDescriptorList *DL) {
310 std::string Transform;
312 for (auto &Field : *Descriptor) {
313 yaml::ScalarNode *Key;
314 yaml::ScalarNode *Value;
315 SmallString<32> KeyStorage;
316 SmallString<32> ValueStorage;
319 Key = dyn_cast<yaml::ScalarNode>(Field.getKey());
321 YS.printError(Field.getKey(), "descriptor key must be a scalar");
325 Value = dyn_cast<yaml::ScalarNode>(Field.getValue());
327 YS.printError(Field.getValue(), "descriptor value must be a scalar");
331 KeyValue = Key->getValue(KeyStorage);
332 if (KeyValue.equals("source")) {
335 Source = Value->getValue(ValueStorage);
336 if (!Regex(Source).isValid(Error)) {
337 YS.printError(Field.getKey(), "invalid regex: " + Error);
340 } else if (KeyValue.equals("target")) {
341 Target = Value->getValue(ValueStorage);
342 } else if (KeyValue.equals("transform")) {
343 Transform = Value->getValue(ValueStorage);
344 } else if (KeyValue.equals("naked")) {
345 std::string Undecorated;
347 Undecorated = Value->getValue(ValueStorage);
348 Naked = StringRef(Undecorated).lower() == "true" || Undecorated == "1";
350 YS.printError(Field.getKey(), "unknown key for function");
355 if (Transform.empty() == Target.empty()) {
356 YS.printError(Descriptor,
357 "exactly one of transform or target must be specified");
361 // TODO see if there is a more elegant solution to selecting the rewrite
364 DL->push_back(llvm::make_unique<ExplicitRewriteFunctionDescriptor>(
365 Source, Target, Naked));
368 llvm::make_unique<PatternRewriteFunctionDescriptor>(Source, Transform));
373 bool RewriteMapParser::
374 parseRewriteGlobalVariableDescriptor(yaml::Stream &YS, yaml::ScalarNode *K,
375 yaml::MappingNode *Descriptor,
376 RewriteDescriptorList *DL) {
379 std::string Transform;
381 for (auto &Field : *Descriptor) {
382 yaml::ScalarNode *Key;
383 yaml::ScalarNode *Value;
384 SmallString<32> KeyStorage;
385 SmallString<32> ValueStorage;
388 Key = dyn_cast<yaml::ScalarNode>(Field.getKey());
390 YS.printError(Field.getKey(), "descriptor Key must be a scalar");
394 Value = dyn_cast<yaml::ScalarNode>(Field.getValue());
396 YS.printError(Field.getValue(), "descriptor value must be a scalar");
400 KeyValue = Key->getValue(KeyStorage);
401 if (KeyValue.equals("source")) {
404 Source = Value->getValue(ValueStorage);
405 if (!Regex(Source).isValid(Error)) {
406 YS.printError(Field.getKey(), "invalid regex: " + Error);
409 } else if (KeyValue.equals("target")) {
410 Target = Value->getValue(ValueStorage);
411 } else if (KeyValue.equals("transform")) {
412 Transform = Value->getValue(ValueStorage);
414 YS.printError(Field.getKey(), "unknown Key for Global Variable");
419 if (Transform.empty() == Target.empty()) {
420 YS.printError(Descriptor,
421 "exactly one of transform or target must be specified");
426 DL->push_back(llvm::make_unique<ExplicitRewriteGlobalVariableDescriptor>(
430 DL->push_back(llvm::make_unique<PatternRewriteGlobalVariableDescriptor>(
436 bool RewriteMapParser::
437 parseRewriteGlobalAliasDescriptor(yaml::Stream &YS, yaml::ScalarNode *K,
438 yaml::MappingNode *Descriptor,
439 RewriteDescriptorList *DL) {
442 std::string Transform;
444 for (auto &Field : *Descriptor) {
445 yaml::ScalarNode *Key;
446 yaml::ScalarNode *Value;
447 SmallString<32> KeyStorage;
448 SmallString<32> ValueStorage;
451 Key = dyn_cast<yaml::ScalarNode>(Field.getKey());
453 YS.printError(Field.getKey(), "descriptor key must be a scalar");
457 Value = dyn_cast<yaml::ScalarNode>(Field.getValue());
459 YS.printError(Field.getValue(), "descriptor value must be a scalar");
463 KeyValue = Key->getValue(KeyStorage);
464 if (KeyValue.equals("source")) {
467 Source = Value->getValue(ValueStorage);
468 if (!Regex(Source).isValid(Error)) {
469 YS.printError(Field.getKey(), "invalid regex: " + Error);
472 } else if (KeyValue.equals("target")) {
473 Target = Value->getValue(ValueStorage);
474 } else if (KeyValue.equals("transform")) {
475 Transform = Value->getValue(ValueStorage);
477 YS.printError(Field.getKey(), "unknown key for Global Alias");
482 if (Transform.empty() == Target.empty()) {
483 YS.printError(Descriptor,
484 "exactly one of transform or target must be specified");
489 DL->push_back(llvm::make_unique<ExplicitRewriteNamedAliasDescriptor>(
493 DL->push_back(llvm::make_unique<PatternRewriteNamedAliasDescriptor>(
500 class RewriteSymbolsLegacyPass : public ModulePass {
502 static char ID; // Pass identification, replacement for typeid
504 RewriteSymbolsLegacyPass();
505 RewriteSymbolsLegacyPass(SymbolRewriter::RewriteDescriptorList &DL);
507 bool runOnModule(Module &M) override;
510 RewriteSymbolPass Impl;
513 char RewriteSymbolsLegacyPass::ID = 0;
515 RewriteSymbolsLegacyPass::RewriteSymbolsLegacyPass() : ModulePass(ID), Impl() {
516 initializeRewriteSymbolsLegacyPassPass(*PassRegistry::getPassRegistry());
519 RewriteSymbolsLegacyPass::RewriteSymbolsLegacyPass(
520 SymbolRewriter::RewriteDescriptorList &DL)
521 : ModulePass(ID), Impl(DL) {}
523 bool RewriteSymbolsLegacyPass::runOnModule(Module &M) {
524 return Impl.runImpl(M);
529 PreservedAnalyses RewriteSymbolPass::run(Module &M, ModuleAnalysisManager &AM) {
531 return PreservedAnalyses::all();
533 return PreservedAnalyses::none();
536 bool RewriteSymbolPass::runImpl(Module &M) {
540 for (auto &Descriptor : Descriptors)
541 Changed |= Descriptor->performOnModule(M);
546 void RewriteSymbolPass::loadAndParseMapFiles() {
547 const std::vector<std::string> MapFiles(RewriteMapFiles);
548 SymbolRewriter::RewriteMapParser Parser;
550 for (const auto &MapFile : MapFiles)
551 Parser.parse(MapFile, &Descriptors);
555 INITIALIZE_PASS(RewriteSymbolsLegacyPass, "rewrite-symbols", "Rewrite Symbols",
558 ModulePass *llvm::createRewriteSymbolsPass() {
559 return new RewriteSymbolsLegacyPass();
563 llvm::createRewriteSymbolsPass(SymbolRewriter::RewriteDescriptorList &DL) {
564 return new RewriteSymbolsLegacyPass(DL);