Support for saving an ordered list of compilation units

[lszekeres]

Summary

This patch supports the reconstruction of an IR level trace from the "events" file generated by the current tracer. This can be done if we know the ordered list of compilation units. This patch extends the coverage pass to pass the name of the compilation unit to the runtime. The runtime half of the patch is submitted separately.

[kcc]

lib/Transforms/Instrumentation/SanitizerCoverage.cpp

195

you can do this shorter, similar to createPrivateNonConstGlobalForString in MemorySanitizer.cpp

[lszekeres]

Addressed comments

lib/Transforms/Instrumentation/SanitizerCoverage.cpp

 
 bool SanitizerCoverageModule::runOnModule(Module &M) {
   if (!CoverageLevel) return false;
   C = &(M.getContext());
   DataLayoutPass *DLP = &getAnalysis<DataLayoutPass>();
   IntptrTy = Type::getIntNTy(*C, DLP->getDataLayout().getPointerSizeInBits());
   Type *VoidTy = Type::getVoidTy(*C);
   IRBuilder<> IRB(*C);
+  Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
   Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
 
   Function *CtorFunc =
       Function::Create(FunctionType::get(VoidTy, false),
                        GlobalValue::InternalLinkage, kSanCovModuleCtorName, &M);
   ReturnInst::Create(*C, BasicBlock::Create(*C, "", CtorFunc));
   appendToGlobalCtors(M, CtorFunc, kSanCtorAndDtorPriority);
 
   SanCovFunction = checkInterfaceFunction(
       M.getOrInsertFunction(kSanCovName, VoidTy, Int32PtrTy, nullptr));
   SanCovWithCheckFunction = checkInterfaceFunction(
       M.getOrInsertFunction(kSanCovWithCheckName, VoidTy, Int32PtrTy, nullptr));
   SanCovIndirCallFunction = checkInterfaceFunction(M.getOrInsertFunction(
       kSanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr));
   SanCovModuleInit = checkInterfaceFunction(
       M.getOrInsertFunction(kSanCovModuleInitName, Type::getVoidTy(*C),
-                            Int32PtrTy, IntptrTy, nullptr));
+                            Int32PtrTy, IntptrTy, Int8PtrTy, nullptr));
   SanCovModuleInit->setLinkage(Function::ExternalLinkage);
   // 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);
 
   if (ClExperimentalTracing) {
     SanCovTraceEnter = checkInterfaceFunction(
GlobalVariable *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();
 
+  // 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);
+
   // Call __sanitizer_cov_module_init
   IRB.SetInsertPoint(CtorFunc->getEntryBlock().getTerminator());
-  IRB.CreateCall2(SanCovModuleInit,
+  IRB.CreateCall3(SanCovModuleInit,
                   IRB.CreatePointerCast(RealGuardArray, Int32PtrTy),
-                  ConstantInt::get(IntptrTy, SanCovFunction->getNumUses()));
+                  ConstantInt::get(IntptrTy, SanCovFunction->getNumUses()),
+                  IRB.CreatePointerCast(ModuleName, Int8PtrTy));
   return true;
 }
 
 bool SanitizerCoverageModule::runOnFunction(Function &F) {
   if (F.empty()) return false;
   if (F.getName().find(".module_ctor") != std::string::npos)
     return false;  // Should not instrument sanitizer init functions.
   if (CoverageLevel >= 3)