[Sanitizer] Introduce SanitizerMetadata class.

It is responsible for generating metadata consumed by sanitizer instrumentation
passes in the backend. Move several methods from CodeGenModule to SanitizerMetadata.
For now the class is stateless, but soon it won't be the case.

Instead of creating globals providing source-level information to ASan, we will create
metadata nodes/strings which will be turned into actual global variables in the
backend (if needed).

No functionality change.

llvm-svn: 214564

1 files changed, 4 insertions, 69 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 55d47060ff9..33325b24e5a 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -88,7 +88,8 @@ CodeGenModule::CodeGenModule(ASTContext &C, const CodeGenOptions &CGO,
       BlockObjectDispose(nullptr), BlockDescriptorType(nullptr),
       GenericBlockLiteralType(nullptr), LifetimeStartFn(nullptr),
       LifetimeEndFn(nullptr), SanitizerBL(llvm::SpecialCaseList::createOrDie(
-                                  CGO.SanitizerBlacklistFile)) {
+                                  CGO.SanitizerBlacklistFile)),
+      SanitizerMD(new SanitizerMetadata(*this)) {
 
   // Initialize the type cache.
   llvm::LLVMContext &LLVMContext = M.getContext();
@@ -1933,7 +1934,7 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
   if (NeedsGlobalCtor || NeedsGlobalDtor)
     EmitCXXGlobalVarDeclInitFunc(D, GV, NeedsGlobalCtor);
 
-  reportGlobalToASan(GV, *D, NeedsGlobalCtor);
+  SanitizerMD->reportGlobalToASan(GV, *D, NeedsGlobalCtor);
 
   // Emit global variable debug information.
   if (CGDebugInfo *DI = getModuleDebugInfo())
@@ -1941,72 +1942,6 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
       DI->EmitGlobalVariable(GV, D);
 }
 
-void CodeGenModule::reportGlobalToASan(llvm::GlobalVariable *GV,
-                                       SourceLocation Loc, StringRef Name,
-                                       bool IsDynInit, bool IsBlacklisted) {
-  if (!LangOpts.Sanitize.Address)
-    return;
-  IsDynInit &= !SanitizerBL.isIn(*GV, "init");
-  IsBlacklisted |= SanitizerBL.isIn(*GV);
-
-  llvm::GlobalVariable *LocDescr = nullptr;
-  llvm::GlobalVariable *GlobalName = nullptr;
-  if (!IsBlacklisted) {
-    // Don't generate source location and global name if it is blacklisted -
-    // it won't be instrumented anyway.
-    PresumedLoc PLoc = Context.getSourceManager().getPresumedLoc(Loc);
-    if (PLoc.isValid()) {
-      llvm::Constant *LocData[] = {
-          GetAddrOfConstantCString(PLoc.getFilename()),
-          llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
-                                 PLoc.getLine()),
-          llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
-                                 PLoc.getColumn()),
-      };
-      auto LocStruct = llvm::ConstantStruct::getAnon(LocData);
-      LocDescr = new llvm::GlobalVariable(TheModule, LocStruct->getType(), true,
-                                          llvm::GlobalValue::PrivateLinkage,
-                                          LocStruct, ".asan_loc_descr");
-      LocDescr->setUnnamedAddr(true);
-      // Add LocDescr to llvm.compiler.used, so that it won't be removed by
-      // the optimizer before the ASan instrumentation pass.
-      addCompilerUsedGlobal(LocDescr);
-    }
-    if (!Name.empty()) {
-      GlobalName = GetAddrOfConstantCString(Name);
-      // GlobalName shouldn't be removed by the optimizer.
-      addCompilerUsedGlobal(GlobalName);
-    }
-  }
-
-  llvm::Value *GlobalMetadata[] = {
-      GV, LocDescr, GlobalName,
-      llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsDynInit),
-      llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsBlacklisted)};
-
-  llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalMetadata);
-  llvm::NamedMDNode *AsanGlobals =
-      TheModule.getOrInsertNamedMetadata("llvm.asan.globals");
-  AsanGlobals->addOperand(ThisGlobal);
-}
-
-void CodeGenModule::reportGlobalToASan(llvm::GlobalVariable *GV,
-                                       const VarDecl &D, bool IsDynInit) {
-  if (!LangOpts.Sanitize.Address)
-    return;
-  std::string QualName;
-  llvm::raw_string_ostream OS(QualName);
-  D.printQualifiedName(OS);
-  reportGlobalToASan(GV, D.getLocation(), OS.str(), IsDynInit);
-}
-
-void CodeGenModule::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
-  // For now, just make sure the global is not modified by the ASan
-  // instrumentation.
-  if (LangOpts.Sanitize.Address)
-    reportGlobalToASan(GV, SourceLocation(), "", false, true);
-}
-
 static bool isVarDeclStrongDefinition(const VarDecl *D, bool NoCommon) {
   // Don't give variables common linkage if -fno-common was specified unless it
   // was overridden by a NoCommon attribute.
@@ -2800,7 +2735,7 @@ CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
   if (Entry)
     *Entry = GV;
 
-  reportGlobalToASan(GV, S->getStrTokenLoc(0), "<string literal>");
+  SanitizerMD->reportGlobalToASan(GV, S->getStrTokenLoc(0), "<string literal>");
   return GV;
 }