// make_decl_llvm - Create the DECL_RTL for a VAR_DECL or FUNCTION_DECL. DECL // should have static storage duration. In other words, it should not be an // automatic variable, including PARM_DECLs. // // There is, however, one exception: this function handles variables explicitly // placed in a particular register by the user. // // This function corresponds to make_decl_rtl in varasm.c, and is implicitly // called by DECL_LLVM if a decl doesn't have an LLVM set. // void make_decl_llvm(tree decl) { #ifdef ENABLE_CHECKING // Check that we are not being given an automatic variable. // A weak alias has TREE_PUBLIC set but not the other bits. if (TREE_CODE(decl) == PARM_DECL || TREE_CODE(decl) == RESULT_DECL || (TREE_CODE(decl) == VAR_DECL && !TREE_STATIC(decl) && !TREE_PUBLIC(decl) && !DECL_EXTERNAL(decl) && !DECL_REGISTER(decl))) abort(); // And that we were not given a type or a label. */ else if (TREE_CODE(decl) == TYPE_DECL || TREE_CODE(decl) == LABEL_DECL) abort (); #endif // For a duplicate declaration, we can be called twice on the // same DECL node. Don't discard the LLVM already made. if (DECL_LLVM_SET_P(decl)) return; if (errorcount || sorrycount) return; // Do not process broken code. // Global register variable with asm name, e.g.: // register unsigned long esp __asm__("ebp"); if (TREE_CODE(decl) != FUNCTION_DECL && DECL_REGISTER(decl)) { // This just verifies that the variable is ok. The actual "load/store" // code paths handle accesses to the variable. ValidateRegisterVariable(decl); return; } timevar_push(TV_LLVM_GLOBALS); const char *Name = ""; if (DECL_NAME(decl)) if (tree AssemblerName = DECL_ASSEMBLER_NAME(decl)) Name = IDENTIFIER_POINTER(AssemblerName); // Now handle ordinary static variables and functions (in memory). // Also handle vars declared register invalidly. if (Name[0] == 1) { #ifdef REGISTER_PREFIX if (strlen (REGISTER_PREFIX) != 0) { int reg_number = decode_reg_name(Name); if (reg_number >= 0 || reg_number == -3) error("%Jregister name given for non-register variable %qD", decl, decl); } #endif } // Specifying a section attribute on a variable forces it into a // non-.bss section, and thus it cannot be common. if (TREE_CODE(decl) == VAR_DECL && DECL_SECTION_NAME(decl) != NULL_TREE && DECL_INITIAL(decl) == NULL_TREE && DECL_COMMON(decl)) DECL_COMMON(decl) = 0; // Variables can't be both common and weak. if (TREE_CODE(decl) == VAR_DECL && DECL_WEAK(decl)) DECL_COMMON(decl) = 0; // Okay, now we need to create an LLVM global variable or function for this // object. Note that this is quite possibly a forward reference to the // object, so its type may change later. if (TREE_CODE(decl) == FUNCTION_DECL) { assert(Name[0] && "Function with empty name!"); // If this function has already been created, reuse the decl. This happens // when we have something like __builtin_memset and memset in the same file. Function *FnEntry = TheModule->getFunction(Name); if (FnEntry == 0) { unsigned CC; const FunctionType *Ty = TheTypeConverter->ConvertFunctionType(TREE_TYPE(decl), decl, NULL, CC); FnEntry = new Function(Ty, Function::ExternalLinkage, Name, TheModule); FnEntry->setCallingConv(CC); // Check for external weak linkage if (DECL_EXTERNAL(decl) && DECL_WEAK(decl)) FnEntry->setLinkage(Function::ExternalWeakLinkage); #ifdef TARGET_ADJUST_LLVM_LINKAGE TARGET_ADJUST_LLVM_LINKAGE(FnEntry,decl); #endif /* TARGET_ADJUST_LLVM_LINKAGE */ // Handle visibility style if (TREE_PUBLIC(decl)) { if (DECL_VISIBILITY(decl) == VISIBILITY_HIDDEN) FnEntry->setVisibility(GlobalValue::HiddenVisibility); else if (DECL_VISIBILITY(decl) == VISIBILITY_PROTECTED) FnEntry->setVisibility(GlobalValue::ProtectedVisibility); } assert(FnEntry->getName() == Name &&"Preexisting fn with the same name!"); } SET_DECL_LLVM(decl, FnEntry); } else { assert((TREE_CODE(decl) == VAR_DECL || TREE_CODE(decl) == CONST_DECL) && "Not a function or var decl?"); const Type *Ty = ConvertType(TREE_TYPE(decl)); GlobalVariable *GV ; // If we have "extern void foo", make the global have type {} instead of // type void. if (Ty == Type::VoidTy) Ty = StructType::get(std::vector<const Type*>(), false); if (Name[0] == 0) { // Global has no name. GV = new GlobalVariable(Ty, false, GlobalValue::ExternalLinkage, 0, "", TheModule); // Check for external weak linkage if (DECL_EXTERNAL(decl) && DECL_WEAK(decl)) GV->setLinkage(GlobalValue::ExternalWeakLinkage); #ifdef TARGET_ADJUST_LLVM_LINKAGE TARGET_ADJUST_LLVM_LINKAGE(GV,decl); #endif /* TARGET_ADJUST_LLVM_LINKAGE */ // Handle visibility style if (TREE_PUBLIC(decl)) { if (DECL_VISIBILITY(decl) == VISIBILITY_HIDDEN) GV->setVisibility(GlobalValue::HiddenVisibility); else if (DECL_VISIBILITY(decl) == VISIBILITY_PROTECTED) GV->setVisibility(GlobalValue::ProtectedVisibility); } } else { // If the global has a name, prevent multiple vars with the same name from // being created. GlobalVariable *GVE = TheModule->getGlobalVariable(Name); if (GVE == 0) { GV = new GlobalVariable(Ty, false, GlobalValue::ExternalLinkage,0, Name, TheModule); // Check for external weak linkage if (DECL_EXTERNAL(decl) && DECL_WEAK(decl)) GV->setLinkage(GlobalValue::ExternalWeakLinkage); #ifdef TARGET_ADJUST_LLVM_LINKAGE TARGET_ADJUST_LLVM_LINKAGE(GV,decl); #endif /* TARGET_ADJUST_LLVM_LINKAGE */ // Handle visibility style if (TREE_PUBLIC(decl)) { if (DECL_VISIBILITY(decl) == VISIBILITY_HIDDEN) GV->setVisibility(GlobalValue::HiddenVisibility); else if (DECL_VISIBILITY(decl) == VISIBILITY_PROTECTED) GV->setVisibility(GlobalValue::ProtectedVisibility); } // If GV got renamed, then there is already an object with this name in // the symbol table. If this happens, the old one must be a forward // decl, just replace it with a cast of the new one. if (GV->getName() != Name) { Function *F = TheModule->getFunction(Name); assert(F && F->isDeclaration() && "A function turned into a global?"); // Replace any uses of "F" with uses of GV. Value *FInNewType = ConstantExpr::getBitCast(GV, F->getType()); F->replaceAllUsesWith(FInNewType); // Update the decl that points to F. changeLLVMValue(F, FInNewType); // Now we can give GV the proper name. GV->takeName(F); // F is now dead, nuke it. F->eraseFromParent(); } } else { GV = GVE; // Global already created, reuse it. } } if ((TREE_READONLY(decl) && !TREE_SIDE_EFFECTS(decl)) || TREE_CODE(decl) == CONST_DECL) { if (DECL_EXTERNAL(decl)) { // Mark external globals constant even though they could be marked // non-constant in the defining translation unit. The definition of the // global determines whether the global is ultimately constant or not, // marking this constant will allow us to do some extra (legal) // optimizations that we would otherwise not be able to do. (In C++, // any global that is 'C++ const' may not be readonly: it could have a // dynamic initializer. // GV->setConstant(true); } else { // Mark readonly globals with constant initializers constant. if (DECL_INITIAL(decl) != error_mark_node && // uninitialized? DECL_INITIAL(decl) && (TREE_CONSTANT(DECL_INITIAL(decl)) || TREE_CODE(DECL_INITIAL(decl)) == STRING_CST)) GV->setConstant(true); } } // Set thread local (TLS) if (TREE_CODE(decl) == VAR_DECL && DECL_THREAD_LOCAL(decl)) GV->setThreadLocal(true); SET_DECL_LLVM(decl, GV); } timevar_pop(TV_LLVM_GLOBALS); }
/// linkGlobalProto - Loop through the global variables in the src module and /// merge them into the dest module. bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) { GlobalValue *DGV = getLinkedToGlobal(SGV); llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility; if (DGV) { // Concatenation of appending linkage variables is magic and handled later. if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage()) return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV); // Determine whether linkage of these two globals follows the source // module's definition or the destination module's definition. GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; GlobalValue::VisibilityTypes NV; bool LinkFromSrc = false; if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc)) return true; NewVisibility = NV; // If we're not linking from the source, then keep the definition that we // have. if (!LinkFromSrc) { // Special case for const propagation. if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) DGVar->setConstant(true); // Set calculated linkage and visibility. DGV->setLinkage(NewLinkage); DGV->setVisibility(*NewVisibility); // Make sure to remember this mapping. ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType())); // Track the source global so that we don't attempt to copy it over when // processing global initializers. DoNotLinkFromSource.insert(SGV); return false; } } // No linking to be performed or linking from the source: simply create an // identical version of the symbol over in the dest module... the // initializer will be filled in later by LinkGlobalInits. GlobalVariable *NewDGV = new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()), SGV->isConstant(), SGV->getLinkage(), /*init*/0, SGV->getName(), /*insertbefore*/0, SGV->isThreadLocal(), SGV->getType()->getAddressSpace()); // Propagate alignment, visibility and section info. CopyGVAttributes(NewDGV, SGV); if (NewVisibility) NewDGV->setVisibility(*NewVisibility); if (DGV) { DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType())); DGV->eraseFromParent(); } // Make sure to remember this mapping. ValueMap[SGV] = NewDGV; return false; }
/// emit_global_to_llvm - Emit the specified VAR_DECL or aggregate CONST_DECL to /// LLVM as a global variable. This function implements the end of /// assemble_variable. void emit_global_to_llvm(tree decl) { if (errorcount || sorrycount) return; // FIXME: Support alignment on globals: DECL_ALIGN. // FIXME: DECL_PRESERVE_P indicates the var is marked with attribute 'used'. // Global register variables don't turn into LLVM GlobalVariables. if (TREE_CODE(decl) == VAR_DECL && DECL_REGISTER(decl)) return; timevar_push(TV_LLVM_GLOBALS); // Get or create the global variable now. GlobalVariable *GV = cast<GlobalVariable>(DECL_LLVM(decl)); // Convert the initializer over. Constant *Init; if (DECL_INITIAL(decl) == 0 || DECL_INITIAL(decl) == error_mark_node) { // This global should be zero initialized. Reconvert the type in case the // forward def of the global and the real def differ in type (e.g. declared // as 'int A[]', and defined as 'int A[100]'). Init = Constant::getNullValue(ConvertType(TREE_TYPE(decl))); } else { assert((TREE_CONSTANT(DECL_INITIAL(decl)) || TREE_CODE(DECL_INITIAL(decl)) == STRING_CST) && "Global initializer should be constant!"); // Temporarily set an initializer for the global, so we don't infinitely // recurse. If we don't do this, we can hit cases where we see "oh a global // with an initializer hasn't been initialized yet, call emit_global_to_llvm // on it". When constructing the initializer it might refer to itself. // this can happen for things like void *G = &G; // GV->setInitializer(UndefValue::get(GV->getType()->getElementType())); Init = TreeConstantToLLVM::Convert(DECL_INITIAL(decl)); } // If we had a forward definition that has a type that disagrees with our // initializer, insert a cast now. This sort of thing occurs when we have a // global union, and the LLVM type followed a union initializer that is // different from the union element used for the type. if (GV->getType()->getElementType() != Init->getType()) { GV->removeFromParent(); GlobalVariable *NGV = new GlobalVariable(Init->getType(), GV->isConstant(), GlobalValue::ExternalLinkage, 0, GV->getName(), TheModule); GV->replaceAllUsesWith(ConstantExpr::getBitCast(NGV, GV->getType())); delete GV; SET_DECL_LLVM(decl, NGV); GV = NGV; } // Set the initializer. GV->setInitializer(Init); // Set thread local (TLS) if (TREE_CODE(decl) == VAR_DECL && DECL_THREAD_LOCAL(decl)) GV->setThreadLocal(true); // Set the linkage. if (!TREE_PUBLIC(decl)) { GV->setLinkage(GlobalValue::InternalLinkage); } else if (DECL_WEAK(decl) || DECL_ONE_ONLY(decl) || (DECL_COMMON(decl) && // DECL_COMMON is only meaningful if no init (!DECL_INITIAL(decl) || DECL_INITIAL(decl) == error_mark_node))) { // llvm-gcc also includes DECL_VIRTUAL_P here. GV->setLinkage(GlobalValue::WeakLinkage); } else if (DECL_COMDAT(decl)) { GV->setLinkage(GlobalValue::LinkOnceLinkage); } #ifdef TARGET_ADJUST_LLVM_LINKAGE TARGET_ADJUST_LLVM_LINKAGE(GV,decl); #endif /* TARGET_ADJUST_LLVM_LINKAGE */ // Handle visibility style if (TREE_PUBLIC(decl)) { if (DECL_VISIBILITY(decl) == VISIBILITY_HIDDEN) GV->setVisibility(GlobalValue::HiddenVisibility); else if (DECL_VISIBILITY(decl) == VISIBILITY_PROTECTED) GV->setVisibility(GlobalValue::ProtectedVisibility); } // Set the section for the global. if (TREE_CODE(decl) == VAR_DECL || TREE_CODE(decl) == CONST_DECL) { if (DECL_SECTION_NAME(decl)) { GV->setSection(TREE_STRING_POINTER(DECL_SECTION_NAME(decl))); #ifdef LLVM_IMPLICIT_TARGET_GLOBAL_VAR_SECTION } else if (const char *Section = LLVM_IMPLICIT_TARGET_GLOBAL_VAR_SECTION(decl)) { GV->setSection(Section); #endif } // Set the alignment for the global if one of the following condition is met // 1) DECL_ALIGN_UNIT does not match alignment as per ABI specification // 2) DECL_ALIGN is set by user. if (DECL_ALIGN_UNIT(decl)) { unsigned TargetAlign = getTargetData().getABITypeAlignment(GV->getType()->getElementType()); if (DECL_USER_ALIGN(decl) || TargetAlign != DECL_ALIGN_UNIT(decl)) GV->setAlignment(DECL_ALIGN_UNIT(decl)); } // Handle used decls if (DECL_PRESERVE_P (decl)) { const Type *SBP= PointerType::get(Type::Int8Ty); AttributeUsedGlobals.push_back(ConstantExpr::getBitCast(GV, SBP)); } // Add annotate attributes for globals if (DECL_ATTRIBUTES(decl)) AddAnnotateAttrsToGlobal(GV, decl); } if (TheDebugInfo) TheDebugInfo->EmitGlobalVariable(GV, decl); timevar_pop(TV_LLVM_GLOBALS); }
bool SanitizerCoverageModule::runOnModule(Module &M) { if (Options.CoverageType == SanitizerCoverageOptions::SCK_None) return false; C = &(M.getContext()); DL = &M.getDataLayout(); CurModule = &M; TargetTriple = Triple(M.getTargetTriple()); HasSancovGuardsSection = false; IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits()); IntptrPtrTy = PointerType::getUnqual(IntptrTy); Type *VoidTy = Type::getVoidTy(*C); IRBuilder<> IRB(*C); Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty()); Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty()); Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty()); Int64Ty = IRB.getInt64Ty(); Int32Ty = IRB.getInt32Ty(); SanCovFunction = checkSanitizerInterfaceFunction( M.getOrInsertFunction(SanCovName, VoidTy, Int32PtrTy, nullptr)); SanCovWithCheckFunction = checkSanitizerInterfaceFunction( M.getOrInsertFunction(SanCovWithCheckName, VoidTy, Int32PtrTy, nullptr)); SanCovTracePCIndir = checkSanitizerInterfaceFunction( M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy, nullptr)); SanCovIndirCallFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction( SanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr)); SanCovTraceCmpFunction[0] = checkSanitizerInterfaceFunction(M.getOrInsertFunction( SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty(), nullptr)); SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction( M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(), IRB.getInt16Ty(), nullptr)); SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction( M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(), IRB.getInt32Ty(), nullptr)); SanCovTraceCmpFunction[3] = checkSanitizerInterfaceFunction(M.getOrInsertFunction( SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty, nullptr)); SanCovTraceDivFunction[0] = checkSanitizerInterfaceFunction(M.getOrInsertFunction( SanCovTraceDiv4, VoidTy, IRB.getInt32Ty(), nullptr)); SanCovTraceDivFunction[1] = checkSanitizerInterfaceFunction(M.getOrInsertFunction( SanCovTraceDiv8, VoidTy, Int64Ty, nullptr)); SanCovTraceGepFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction( SanCovTraceGep, VoidTy, IntptrTy, nullptr)); SanCovTraceSwitchFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction( SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy, nullptr)); // We insert an empty inline asm after cov callbacks to avoid callback merge. EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), StringRef(""), StringRef(""), /*hasSideEffects=*/true); SanCovTracePC = checkSanitizerInterfaceFunction( M.getOrInsertFunction(SanCovTracePCName, VoidTy, nullptr)); SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction( SanCovTracePCGuardName, VoidTy, Int32PtrTy, nullptr)); SanCovTraceEnter = checkSanitizerInterfaceFunction( M.getOrInsertFunction(SanCovTraceEnterName, VoidTy, Int32PtrTy, nullptr)); SanCovTraceBB = checkSanitizerInterfaceFunction( M.getOrInsertFunction(SanCovTraceBBName, VoidTy, Int32PtrTy, nullptr)); // At this point we create a dummy array of guards because we don't // know how many elements we will need. Type *Int32Ty = IRB.getInt32Ty(); Type *Int8Ty = IRB.getInt8Ty(); if (!Options.TracePCGuard) GuardArray = new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage, nullptr, "__sancov_gen_cov_tmp"); if (Options.Use8bitCounters) EightBitCounterArray = new GlobalVariable(M, Int8Ty, false, GlobalVariable::ExternalLinkage, nullptr, "__sancov_gen_cov_tmp"); for (auto &F : M) runOnFunction(F); auto N = NumberOfInstrumentedBlocks(); GlobalVariable *RealGuardArray = nullptr; if (!Options.TracePCGuard) { // Now we know how many elements we need. Create an array of guards // with one extra element at the beginning for the size. Type *Int32ArrayNTy = ArrayType::get(Int32Ty, N + 1); RealGuardArray = new GlobalVariable( M, Int32ArrayNTy, false, GlobalValue::PrivateLinkage, Constant::getNullValue(Int32ArrayNTy), "__sancov_gen_cov"); // Replace the dummy array with the real one. GuardArray->replaceAllUsesWith( IRB.CreatePointerCast(RealGuardArray, Int32PtrTy)); GuardArray->eraseFromParent(); } GlobalVariable *RealEightBitCounterArray; if (Options.Use8bitCounters) { // Make sure the array is 16-aligned. static const int CounterAlignment = 16; Type *Int8ArrayNTy = ArrayType::get(Int8Ty, alignTo(N, CounterAlignment)); RealEightBitCounterArray = new GlobalVariable( M, Int8ArrayNTy, false, GlobalValue::PrivateLinkage, Constant::getNullValue(Int8ArrayNTy), "__sancov_gen_cov_counter"); RealEightBitCounterArray->setAlignment(CounterAlignment); EightBitCounterArray->replaceAllUsesWith( IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy)); EightBitCounterArray->eraseFromParent(); } // Create variable for module (compilation unit) name Constant *ModNameStrConst = ConstantDataArray::getString(M.getContext(), M.getName(), true); GlobalVariable *ModuleName = new GlobalVariable( M, ModNameStrConst->getType(), true, GlobalValue::PrivateLinkage, ModNameStrConst, "__sancov_gen_modname"); if (Options.TracePCGuard) { if (HasSancovGuardsSection) { Function *CtorFunc; GlobalVariable *SecStart = new GlobalVariable( M, Int32PtrTy, false, GlobalVariable::ExternalLinkage, nullptr, getSanCovTracePCGuardSectionStart()); SecStart->setVisibility(GlobalValue::HiddenVisibility); GlobalVariable *SecEnd = new GlobalVariable( M, Int32PtrTy, false, GlobalVariable::ExternalLinkage, nullptr, getSanCovTracePCGuardSectionEnd()); SecEnd->setVisibility(GlobalValue::HiddenVisibility); std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions( M, SanCovModuleCtorName, SanCovTracePCGuardInitName, {Int32PtrTy, Int32PtrTy}, {IRB.CreatePointerCast(SecStart, Int32PtrTy), IRB.CreatePointerCast(SecEnd, Int32PtrTy)}); if (TargetTriple.supportsCOMDAT()) { // Use comdat to dedup CtorFunc. CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName)); appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc); } else { appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority); } } } else if (!Options.TracePC) { Function *CtorFunc; std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions( M, SanCovModuleCtorName, SanCovModuleInitName, {Int32PtrTy, IntptrTy, Int8PtrTy, Int8PtrTy}, {IRB.CreatePointerCast(RealGuardArray, Int32PtrTy), ConstantInt::get(IntptrTy, N), Options.Use8bitCounters ? IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy) : Constant::getNullValue(Int8PtrTy), IRB.CreatePointerCast(ModuleName, Int8PtrTy)}); appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority); } return true; }