/// Remove any debug info for global variables/functions in the given module for /// which said global variable/function no longer exists (i.e. is null). /// /// Debugging information is encoded in llvm IR using metadata. This is designed /// such a way that debug info for symbols preserved even if symbols are /// optimized away by the optimizer. This special pass removes debug info for /// such symbols. bool StripDeadDebugInfo::runOnModule(Module &M) { bool Changed = false; LLVMContext &C = M.getContext(); // Find all debug info in F. This is actually overkill in terms of what we // want to do, but we want to try and be as resilient as possible in the face // of potential debug info changes by using the formal interfaces given to us // as much as possible. DebugInfoFinder F; F.processModule(M); // For each compile unit, find the live set of global variables/functions and // replace the current list of potentially dead global variables/functions // with the live list. SmallVector<Value *, 64> LiveGlobalVariables; SmallVector<Value *, 64> LiveSubprograms; DenseSet<const MDNode *> VisitedSet; for (DICompileUnit DIC : F.compile_units()) { assert(DIC.Verify() && "DIC must verify as a DICompileUnit."); // Create our live subprogram list. DIArray SPs = DIC.getSubprograms(); bool SubprogramChange = false; for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) { DISubprogram DISP(SPs.getElement(i)); assert(DISP.Verify() && "DISP must verify as a DISubprogram."); // Make sure we visit each subprogram only once. if (!VisitedSet.insert(DISP).second) continue; // If the function referenced by DISP is not null, the function is live. if (DISP.getFunction()) LiveSubprograms.push_back(DISP); else SubprogramChange = true; } // Create our live global variable list. DIArray GVs = DIC.getGlobalVariables(); bool GlobalVariableChange = false; for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i) { DIGlobalVariable DIG(GVs.getElement(i)); assert(DIG.Verify() && "DIG must verify as DIGlobalVariable."); // Make sure we only visit each global variable only once. if (!VisitedSet.insert(DIG).second) continue; // If the global variable referenced by DIG is not null, the global // variable is live. if (DIG.getGlobal()) LiveGlobalVariables.push_back(DIG); else GlobalVariableChange = true; } // If we found dead subprograms or global variables, replace the current // subprogram list/global variable list with our new live subprogram/global // variable list. if (SubprogramChange) { // Make sure that 9 is still the index of the subprograms. This is to make // sure that an assert is hit if the location of the subprogram array // changes. This is just to make sure that this is updated if such an // event occurs. assert(DIC->getNumOperands() >= 10 && SPs == DIC->getOperand(9) && "DICompileUnits is expected to store Subprograms in operand " "9."); DIC->replaceOperandWith(9, MDNode::get(C, LiveSubprograms)); Changed = true; } if (GlobalVariableChange) { // Make sure that 10 is still the index of global variables. This is to // make sure that an assert is hit if the location of the subprogram array // changes. This is just to make sure that this index is updated if such // an event occurs. assert(DIC->getNumOperands() >= 11 && GVs == DIC->getOperand(10) && "DICompileUnits is expected to store Global Variables in operand " "10."); DIC->replaceOperandWith(10, MDNode::get(C, LiveGlobalVariables)); Changed = true; } // Reset lists for the next iteration. LiveSubprograms.clear(); LiveGlobalVariables.clear(); } return Changed; }
void GCOVProfiler::emitProfileNotes() { NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu"); if (!CU_Nodes) return; for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) { // Each compile unit gets its own .gcno file. This means that whether we run // this pass over the original .o's as they're produced, or run it after // LTO, we'll generate the same .gcno files. DICompileUnit CU(CU_Nodes->getOperand(i)); std::error_code EC; raw_fd_ostream out(mangleName(CU, "gcno"), EC, sys::fs::F_None); std::string EdgeDestinations; DIArray SPs = CU.getSubprograms(); unsigned FunctionIdent = 0; for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) { DISubprogram SP(SPs.getElement(i)); assert((!SP || SP.isSubprogram()) && "A MDNode in subprograms of a CU should be null or a DISubprogram."); if (!SP) continue; Function *F = SP.getFunction(); if (!F) continue; if (!functionHasLines(F)) continue; // gcov expects every function to start with an entry block that has a // single successor, so split the entry block to make sure of that. BasicBlock &EntryBlock = F->getEntryBlock(); BasicBlock::iterator It = EntryBlock.begin(); while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It)) ++It; EntryBlock.splitBasicBlock(It); Funcs.push_back(make_unique<GCOVFunction>(SP, &out, FunctionIdent++, Options.UseCfgChecksum, Options.ExitBlockBeforeBody)); GCOVFunction &Func = *Funcs.back(); for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { GCOVBlock &Block = Func.getBlock(BB); TerminatorInst *TI = BB->getTerminator(); if (int successors = TI->getNumSuccessors()) { for (int i = 0; i != successors; ++i) { Block.addEdge(Func.getBlock(TI->getSuccessor(i))); } } else if (isa<ReturnInst>(TI)) { Block.addEdge(Func.getReturnBlock()); } uint32_t Line = 0; for (BasicBlock::iterator I = BB->begin(), IE = BB->end(); I != IE; ++I) { // Debug intrinsic locations correspond to the location of the // declaration, not necessarily any statements or expressions. if (isa<DbgInfoIntrinsic>(I)) continue; const DebugLoc &Loc = I->getDebugLoc(); if (!Loc) continue; // Artificial lines such as calls to the global constructors. if (Loc.getLine() == 0) continue; if (Line == Loc.getLine()) continue; Line = Loc.getLine(); if (SP != getDISubprogram(Loc.getScope())) continue; GCOVLines &Lines = Block.getFile(SP.getFilename()); Lines.addLine(Loc.getLine()); } } EdgeDestinations += Func.getEdgeDestinations(); } FileChecksums.push_back(hash_value(EdgeDestinations)); out.write("oncg", 4); out.write(ReversedVersion, 4); out.write(reinterpret_cast<char*>(&FileChecksums.back()), 4); for (auto &Func : Funcs) { Func->setCfgChecksum(FileChecksums.back()); Func->writeOut(); } out.write("\0\0\0\0\0\0\0\0", 8); // EOF out.close(); } }
void DICompositeType::printInternal(raw_ostream &OS) const { DIType::printInternal(OS); DIArray A = getTypeArray(); OS << " [" << A.getNumElements() << " elements]"; }