1 //===- CodeGeneratorBug.cpp - Debug code generation bugs ------------------===//
3 // This file implements program code generation debugging support.
5 //===----------------------------------------------------------------------===//
8 #include "SystemUtils.h"
9 #include "ListReducer.h"
10 #include "llvm/Constants.h"
11 #include "llvm/DerivedTypes.h"
12 #include "llvm/GlobalValue.h"
13 #include "llvm/iMemory.h"
14 #include "llvm/iTerminators.h"
15 #include "llvm/iOther.h"
16 #include "llvm/Module.h"
17 #include "llvm/Pass.h"
18 #include "llvm/Analysis/Verifier.h"
19 #include "llvm/Support/Mangler.h"
20 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
21 #include "llvm/Transforms/Utils/Cloning.h"
22 #include "llvm/Transforms/Utils/Linker.h"
23 #include "Support/Statistic.h"
24 #include "Support/StringExtras.h"
28 class ReduceMisCodegenFunctions : public ListReducer<Function*> {
31 ReduceMisCodegenFunctions(BugDriver &bd) : BD(bd) {}
33 virtual TestResult doTest(std::vector<Function*> &Prefix,
34 std::vector<Function*> &Suffix) {
35 if (!Prefix.empty() && TestFuncs(Prefix))
37 if (!Suffix.empty() && TestFuncs(Suffix))
42 bool TestFuncs(const std::vector<Function*> &CodegenTest,
43 bool KeepFiles = false);
47 bool ReduceMisCodegenFunctions::TestFuncs(const std::vector<Function*> &Funcs,
50 DEBUG(std::cerr << "Test functions are:\n");
51 for (std::vector<Function*>::const_iterator I = Funcs.begin(),E = Funcs.end();
53 DEBUG(std::cerr << "\t" << (*I)->getName() << "\n");
55 // Clone the module for the two halves of the program we want.
56 Module *SafeModule = CloneModule(BD.Program);
58 // Make sure functions & globals are all external so that linkage
59 // between the two modules will work.
60 for (Module::iterator I = SafeModule->begin(), E = SafeModule->end();I!=E;++I)
61 I->setLinkage(GlobalValue::ExternalLinkage);
62 for (Module::giterator I=SafeModule->gbegin(),E = SafeModule->gend();I!=E;++I)
63 I->setLinkage(GlobalValue::ExternalLinkage);
65 Module *TestModule = CloneModule(SafeModule);
67 // Make sure global initializers exist only in the safe module (CBE->.so)
68 for (Module::giterator I=TestModule->gbegin(),E = TestModule->gend();I!=E;++I)
69 I->setInitializer(0); // Delete the initializer to make it external
71 // Remove the Test functions from the Safe module
72 for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
73 Function *TNOF = SafeModule->getFunction(Funcs[i]->getName(),
74 Funcs[i]->getFunctionType());
75 DEBUG(std::cerr << "Removing function " << Funcs[i]->getName() << "\n");
76 assert(TNOF && "Function doesn't exist in module!");
77 DeleteFunctionBody(TNOF); // Function is now external in this module!
80 // Remove the Safe functions from the Test module
81 for (Module::iterator I=TestModule->begin(),E=TestModule->end(); I!=E; ++I) {
82 bool funcFound = false;
83 for (std::vector<Function*>::const_iterator F=Funcs.begin(),Fe=Funcs.end();
85 if (I->getName() == (*F)->getName()) funcFound = true;
87 if (!funcFound && !(BD.isExecutingJIT() && I->getName() == "main"))
88 DeleteFunctionBody(I);
91 // This is only applicable if we are debugging the JIT:
92 // Find all external functions in the Safe modules that are actually used
93 // (called or taken address of), and make them call the JIT wrapper instead
94 if (BD.isExecutingJIT()) {
95 // Must delete `main' from Safe module if it has it
96 Function *safeMain = SafeModule->getNamedFunction("main");
97 assert(safeMain && "`main' function not found in safe module!");
98 DeleteFunctionBody(safeMain);
100 // Add an external function "getPointerToNamedFunction" that JIT provides
101 // Prototype: void *getPointerToNamedFunction(const char* Name)
102 std::vector<const Type*> Params;
103 Params.push_back(PointerType::get(Type::SByteTy)); // std::string&
104 FunctionType *resolverTy = FunctionType::get(PointerType::get(Type::VoidTy),
105 Params, false /* isVarArg */);
106 Function *resolverFunc = new Function(resolverTy,
107 GlobalValue::ExternalLinkage,
108 "getPointerToNamedFunction",
111 // Use the function we just added to get addresses of functions we need
112 // Iterate over the global declarations in the Safe module
113 for (Module::iterator F=SafeModule->begin(),E=SafeModule->end(); F!=E; ++F){
114 if (F->isExternal() && !F->use_empty() && &(*F) != resolverFunc) {
115 // If it has a non-zero use list,
116 // 1. Add a string constant with its name to the global file
117 // The correct type is `const [ NUM x sbyte ]' where NUM is length of
119 const std::string &Name = F->getName();
120 GlobalVariable *funcName =
121 new GlobalVariable(ArrayType::get(Type::SByteTy, Name.length()+1),
122 true /* isConstant */,
123 GlobalValue::InternalLinkage,
124 ConstantArray::get(Name),
128 // 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an
129 // sbyte* so it matches the signature of the resolver function.
130 std::vector<Constant*> GEPargs(2, Constant::getNullValue(Type::LongTy));
132 // 3. Replace all uses of `func' with calls to resolver by:
133 // (a) Iterating through the list of uses of this function
134 // (b) Insert a cast instruction in front of each use
135 // (c) Replace use of old call with new call
137 // GetElementPtr *funcName, ulong 0, ulong 0
139 ConstantExpr::getGetElementPtr(ConstantPointerRef::get(funcName),
141 std::vector<Value*> ResolverArgs;
142 ResolverArgs.push_back(GEP);
144 // Insert code at the beginning of the function
145 for (Value::use_iterator i=F->use_begin(), e=F->use_end(); i!=e; ++i) {
146 if (Instruction* Inst = dyn_cast<Instruction>(*i)) {
147 // call resolver(GetElementPtr...)
148 CallInst *resolve = new CallInst(resolverFunc, ResolverArgs,
150 // cast the result from the resolver to correctly-typed function
151 CastInst *castResolver =
152 new CastInst(resolve, PointerType::get(F->getFunctionType()),
154 // actually use the resolved function
155 Inst->replaceUsesOfWith(F, castResolver);
157 // FIXME: need to take care of cases where a function is used that
158 // is not an instruction, e.g. global variable initializer...
159 std::cerr << "Non-instruction is using an external function!\n";
167 DEBUG(std::cerr << "Safe module:\n";
168 typedef Module::iterator MI;
169 typedef Module::giterator MGI;
171 for (MI I = SafeModule->begin(), E = SafeModule->end(); I != E; ++I)
172 if (!I->isExternal()) std::cerr << "\t" << I->getName() << "\n";
173 for (MGI I = SafeModule->gbegin(), E = SafeModule->gend(); I!=E; ++I)
174 if (!I->isExternal()) std::cerr << "\t" << I->getName() << "\n";
176 std::cerr << "Test module:\n";
177 for (MI I = TestModule->begin(), E = TestModule->end(); I != E; ++I)
178 if (!I->isExternal()) std::cerr << "\t" << I->getName() << "\n";
179 for (MGI I=TestModule->gbegin(),E = TestModule->gend(); I!= E; ++I)
180 if (!I->isExternal()) std::cerr << "\t" << I->getName() << "\n";
183 // Write out the bytecode to be sent to CBE
184 std::string SafeModuleBC = getUniqueFilename("bugpoint.safe.bc");
185 if (verifyModule(*SafeModule)) {
186 std::cerr << "Bytecode file corrupted!\n";
189 if (BD.writeProgramToFile(SafeModuleBC, SafeModule)) {
190 std::cerr << "Error writing bytecode to `" << SafeModuleBC << "'\nExiting.";
194 // Make a shared library
195 std::string SharedObject;
196 BD.compileSharedObject(SafeModuleBC, SharedObject);
198 // Remove all functions from the Test module EXCEPT for the ones specified in
199 // Funcs. We know which ones these are because they are non-external in
200 // ToOptimize, but external in ToNotOptimize.
202 for (Module::iterator I = TestModule->begin(), E = TestModule->end();I!=E;++I)
203 if (!I->isExternal()) {
204 Function *TNOF = SafeModule->getFunction(I->getName(),
205 I->getFunctionType());
206 assert(TNOF && "Function doesn't exist in ToNotOptimize module??");
207 if (!TNOF->isExternal())
208 DeleteFunctionBody(I);
211 std::string TestModuleBC = getUniqueFilename("bugpoint.test.bc");
212 if (verifyModule(*TestModule)) {
213 std::cerr << "Bytecode file corrupted!\n";
216 if (BD.writeProgramToFile(TestModuleBC, TestModule)) {
217 std::cerr << "Error writing bytecode to `" << SafeModuleBC << "'\nExiting.";
224 // Run the code generator on the `Test' code, loading the shared library.
225 // The function returns whether or not the new output differs from reference.
226 int Result = BD.diffProgram(TestModuleBC, SharedObject, false);
228 std::cout << "You can reproduce the problem with the command line: \n"
229 << (BD.isExecutingJIT() ? "lli" : "llc")
230 << " -load " << SharedObject << " " << TestModuleBC
233 removeFile(TestModuleBC);
234 removeFile(SafeModuleBC);
235 removeFile(SharedObject);
241 struct Disambiguator {
242 std::set<std::string> SymbolNames;
243 std::set<GlobalValue*> Symbols;
244 uint64_t uniqueCounter;
247 Disambiguator() : uniqueCounter(0), externalOnly(true) {}
248 void setExternalOnly(bool value) { externalOnly = value; }
249 void add(GlobalValue &V) {
250 // If we're only processing externals and this isn't external, bail
251 if (externalOnly && !V.isExternal()) return;
252 // If we're already processed this symbol, don't add it again
253 if (Symbols.count(&V) != 0) return;
255 std::string SymName = V.getName();
257 // Use the Mangler facility to make symbol names that will be valid in
259 SymName = Mangler::makeNameProper(SymName);
262 if (SymbolNames.count(SymName) == 0) {
263 DEBUG(std::cerr << "Disambiguator: adding " << SymName
264 << ", no conflicts.\n");
265 SymbolNames.insert(SymName);
267 // Mangle name before adding
270 newName = SymName + "_" + utostr(uniqueCounter);
271 if (SymbolNames.count(newName) == 0) break;
272 else ++uniqueCounter;
274 //while (SymbolNames.count(V->getName()+utostr(uniqueCounter++))==0);
275 DEBUG(std::cerr << "Disambiguator: conflict: " << SymName
276 << ", adding: " << newName << "\n");
278 SymbolNames.insert(newName);
285 void DisambiguateGlobalSymbols(Module *M) {
286 // First, try not to cause collisions by minimizing chances of renaming an
287 // already-external symbol, so take in external globals and functions as-is.
289 DEBUG(std::cerr << "Disambiguating globals (external-only)\n");
290 for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I) D.add(*I);
291 DEBUG(std::cerr << "Disambiguating functions (external-only)\n");
292 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) D.add(*I);
294 // Now just rename functions and globals as necessary, keeping what's already
295 // in the set unique.
296 D.setExternalOnly(false);
297 DEBUG(std::cerr << "Disambiguating globals\n");
298 for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I) D.add(*I);
299 DEBUG(std::cerr << "Disambiguating globals\n");
300 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) D.add(*I);
304 bool BugDriver::debugCodeGenerator() {
305 // See if we can pin down which functions are being miscompiled...
306 //First, build a list of all of the non-external functions in the program.
307 std::vector<Function*> MisCodegenFunctions;
308 for (Module::iterator I = Program->begin(), E = Program->end(); I != E; ++I)
309 if (!I->isExternal())
310 MisCodegenFunctions.push_back(I);
312 // If we are executing the JIT, we *must* keep the function `main' in the
313 // module that is passed in, and not the shared library. However, we still
314 // want to be able to debug the `main' function alone. Thus, we create a new
315 // function `main' which just calls the old one.
316 if (isExecutingJIT()) {
317 // Get the `main' function
318 Function *oldMain = Program->getNamedFunction("main");
319 assert(oldMain && "`main' function not found in program!");
321 oldMain->setName("old_main");
322 // Create a NEW `main' function with same type
323 Function *newMain = new Function(oldMain->getFunctionType(),
324 GlobalValue::ExternalLinkage,
326 // Call the old main function and return its result
327 BasicBlock *BB = new BasicBlock("entry", newMain);
328 std::vector<Value*> args;
329 for (Function::aiterator I=newMain->abegin(), E=newMain->aend(); I!=E; ++I)
331 CallInst *call = new CallInst(oldMain, args);
332 BB->getInstList().push_back(call);
334 // if the type of old function wasn't void, return value of call
336 if (oldMain->getReturnType() != Type::VoidTy) {
337 ret = new ReturnInst(call);
339 ret = new ReturnInst();
342 // Add the return instruction to the BasicBlock
343 BB->getInstList().push_back(ret);
346 DisambiguateGlobalSymbols(Program);
348 // Do the reduction...
349 ReduceMisCodegenFunctions(*this).reduceList(MisCodegenFunctions);
351 std::cout << "\n*** The following functions are being miscompiled: ";
352 PrintFunctionList(MisCodegenFunctions);
355 // Output a bunch of bytecode files for the user...
356 ReduceMisCodegenFunctions(*this).TestFuncs(MisCodegenFunctions, true);