CFI: Introduce -fsanitize=cfi-icall flag.

This flag causes the compiler to emit bit set entries for functions as well
as runtime bitset checks at indirect call sites. Depends on the new function
bitset mechanism.

Differential Revision: http://reviews.llvm.org/D11857

llvm-svn: 247238

1 files changed, 15 insertions, 5 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index a2d554bde54..8f0259d502a 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -941,6 +941,20 @@ void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F,
   if (FD->isReplaceableGlobalAllocationFunction())
     F->addAttribute(llvm::AttributeSet::FunctionIndex,
                     llvm::Attribute::NoBuiltin);
+
+  // If we are checking indirect calls and this is not a non-static member
+  // function, emit a bit set entry for the function type.
+  if (LangOpts.Sanitize.has(SanitizerKind::CFIICall) &&
+      !(isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic())) {
+    llvm::NamedMDNode *BitsetsMD =
+        getModule().getOrInsertNamedMetadata("llvm.bitsets");
+
+    llvm::Metadata *BitsetOps[] = {
+        CreateMetadataIdentifierForType(FD->getType()),
+        llvm::ConstantAsMetadata::get(F),
+        llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(Int64Ty, 0))};
+    BitsetsMD->addOperand(llvm::MDTuple::get(getLLVMContext(), BitsetOps));
+  }
 }
 
 void CodeGenModule::addUsedGlobal(llvm::GlobalValue *GV) {
@@ -3824,12 +3838,8 @@ llvm::Metadata *CodeGenModule::CreateMetadataIdentifierForType(QualType T) {
 
 llvm::MDTuple *CodeGenModule::CreateVTableBitSetEntry(
     llvm::GlobalVariable *VTable, CharUnits Offset, const CXXRecordDecl *RD) {
-  std::string OutName;
-  llvm::raw_string_ostream Out(OutName);
-  getCXXABI().getMangleContext().mangleCXXVTableBitSet(RD, Out);
-
   llvm::Metadata *BitsetOps[] = {
-      llvm::MDString::get(getLLVMContext(), Out.str()),
+      CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0)),
       llvm::ConstantAsMetadata::get(VTable),
       llvm::ConstantAsMetadata::get(
           llvm::ConstantInt::get(Int64Ty, Offset.getQuantity()))};