[ubsan] Diagnose noreturn functions which return

Diagnose 'unreachable' UB when a noreturn function returns.

  1. Insert a check at the end of functions marked noreturn.

  2. A decl may be marked noreturn in the caller TU, but not marked in
     the TU where it's defined. To diagnose this scenario, strip away the
     noreturn attribute on the callee and insert check after calls to it.

Testing: check-clang, check-ubsan, check-ubsan-minimal, D40700

rdar://33660464

Differential Revision: https://reviews.llvm.org/D40698

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@321231 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 1 deletions

diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 98740e8f9a..b61b273977 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -3076,6 +3076,17 @@ void CodeGenFunction::EmitCfiCheckFail() {
   CGM.addUsedGlobal(F);
 }
 
+void CodeGenFunction::EmitUnreachable(SourceLocation Loc) {
+  if (SanOpts.has(SanitizerKind::Unreachable)) {
+    SanitizerScope SanScope(this);
+    EmitCheck(std::make_pair(static_cast<llvm::Value *>(Builder.getFalse()),
+                             SanitizerKind::Unreachable),
+              SanitizerHandler::BuiltinUnreachable,
+              EmitCheckSourceLocation(Loc), None);
+  }
+  Builder.CreateUnreachable();
+}
+
 void CodeGenFunction::EmitTrapCheck(llvm::Value *Checked) {
   llvm::BasicBlock *Cont = createBasicBlock("cont");
 
@@ -4616,7 +4627,7 @@ RValue CodeGenFunction::EmitCall(QualType CalleeType, const CGCallee &OrigCallee
     Callee.setFunctionPointer(CalleePtr);
   }
 
-  return EmitCall(FnInfo, Callee, ReturnValue, Args);
+  return EmitCall(FnInfo, Callee, ReturnValue, Args, nullptr, E->getExprLoc());
 }
 
 LValue CodeGenFunction::