[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

llvm-svn: 321231

1 files changed, 12 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index ab5bbc03db9..c6ee97142aa 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -3288,11 +3288,15 @@ public:
   /// LLVM arguments and the types they were derived from.
   RValue EmitCall(const CGFunctionInfo &CallInfo, const CGCallee &Callee,
                   ReturnValueSlot ReturnValue, const CallArgList &Args,
-                  llvm::Instruction **callOrInvoke = nullptr);
-
+                  llvm::Instruction **callOrInvoke, SourceLocation Loc);
+  RValue EmitCall(const CGFunctionInfo &CallInfo, const CGCallee &Callee,
+                  ReturnValueSlot ReturnValue, const CallArgList &Args,
+                  llvm::Instruction **callOrInvoke = nullptr) {
+    return EmitCall(CallInfo, Callee, ReturnValue, Args, callOrInvoke,
+                    SourceLocation());
+  }
   RValue EmitCall(QualType FnType, const CGCallee &Callee, const CallExpr *E,
-                  ReturnValueSlot ReturnValue,
-                  llvm::Value *Chain = nullptr);
+                  ReturnValueSlot ReturnValue, llvm::Value *Chain = nullptr);
   RValue EmitCallExpr(const CallExpr *E,
                       ReturnValueSlot ReturnValue = ReturnValueSlot());
   RValue EmitSimpleCallExpr(const CallExpr *E, ReturnValueSlot ReturnValue);
@@ -3747,6 +3751,10 @@ public:
                             llvm::ConstantInt *TypeId, llvm::Value *Ptr,
                             ArrayRef<llvm::Constant *> StaticArgs);
 
+  /// Emit a reached-unreachable diagnostic if \p Loc is valid and runtime
+  /// checking is enabled. Otherwise, just emit an unreachable instruction.
+  void EmitUnreachable(SourceLocation Loc);
+
   /// \brief Create a basic block that will call the trap intrinsic, and emit a
   /// conditional branch to it, for the -ftrapv checks.
   void EmitTrapCheck(llvm::Value *Checked);