emit_DW_AT_noreturn flag

[vleschuk]

Summary

Emit DWARF DW_AT_noreturn for C++ [[ noreturn ]] and C _Noreturn specifiers.

Corresponding LLVM patch: https://reviews.llvm.org/D23167

[majnemer]

This has no tests.

[vleschuk]

More context. Slight formatting changes.

[aprantl]

Please add separate testcases for C11 and C++11 (and possibly Objective-C?).

[vleschuk]

Add IR tests

[aprantl]

test/Frontend/dinoreturn.c

3

Please check for more context. For example:

CHECK: !DISubprogram({{.*}}name: "f"{{.*}}flags: DIFlagNoreturn

would be good here.

[vleschuk]

More context in text.

[vleschuk]

Full context

[vleschuk]

Could somebody take a look at it and commit if no ojections?

[aprantl]

Note that I moved the test cases to the appropriate CodeGenXYZ directories.

[aprantl]

Committed as r278942. Thanks!

lib/AST/Decl.cpp

if (const auto *Namespace = cast<NamespaceDecl>(DC)) {
       break;
     }
   }
 
   return true;
 }
 
 bool FunctionDecl::isNoReturn() const {
-  return hasAttr<NoReturnAttr>() || hasAttr<CXX11NoReturnAttr>() ||
-         hasAttr<C11NoReturnAttr>() ||
-         getType()->getAs<FunctionType>()->getNoReturnAttr();
+  bool HasNoReturnAttr = hasAttr<NoReturnAttr>() || hasAttr<CXX11NoReturnAttr>()
+                         || hasAttr<C11NoReturnAttr>();
+  const auto *FuncType = getType()->getAs<FunctionType>();
+  bool TypeHasNoReturnAttr = false;
+  if (FuncType)
+    TypeHasNoReturnAttr = FuncType->getNoReturnAttr();
+  return HasNoReturnAttr || TypeHasNoReturnAttr;
 }
 
 void
 FunctionDecl::setPreviousDeclaration(FunctionDecl *PrevDecl) {
   redeclarable_base::setPreviousDecl(PrevDecl);
 
   if (FunctionTemplateDecl *FunTmpl = getDescribedFunctionTemplate()) {
     FunctionTemplateDecl *PrevFunTmpl

lib/CodeGen/CGDebugInfo.cpp

if (DebugKind >= codegenoptions::LimitedDebugInfo) {
     if (const NamespaceDecl *NSDecl =
         dyn_cast_or_null<NamespaceDecl>(FD->getDeclContext()))
       FDContext = getOrCreateNameSpace(NSDecl);
     else if (const RecordDecl *RDecl =
              dyn_cast_or_null<RecordDecl>(FD->getDeclContext())) {
       llvm::DIScope *Mod = getParentModuleOrNull(RDecl);
       FDContext = getContextDescriptor(RDecl, Mod ? Mod : TheCU);
     }
+    // Check if it is a noreturn-marked function
+    if (FD->isNoReturn())
+      Flags |= llvm::DINode::FlagNoReturn;
     // Collect template parameters.
     TParamsArray = CollectFunctionTemplateParams(FD, Unit);
   }
 }
 
 void CGDebugInfo::collectVarDeclProps(const VarDecl *VD, llvm::DIFile *&Unit,
                                       unsigned &LineNo, QualType &T,
                                       StringRef &Name, StringRef &LinkageName,

test/Frontend/dinoreturn.c

+// RUN: %clang %s -c -std=c11 -emit-llvm -S -g -o - | FileCheck %s
+// CHECK: !DISubprogram({{.*}}name: "f"{{.*}}flags:{{.*DIFlagNoReturn}}
+#include <stdlib.h>
+_Noreturn void f() {
+  exit(0);
+}

test/Frontend/dinoreturn.cpp

+// RUN: %clang %s -c -std=c++11 -x c++ -emit-llvm -S -g -o - | FileCheck %s
+// CHECK: !DISubprogram({{.*}}name: "f"{{.*}}flags:{{.*DIFlagNoReturn}}
+[[ noreturn ]] void f() {
+  throw 1;
+}

test/Frontend/dinoreturn.m

+// RUN: %clang %s -c -emit-llvm -S -g -o - | FileCheck %s
+// CHECK: !DISubprogram({{.*}}name: "f"{{.*}}flags:{{.*DIFlagNoReturn}}
+__attribute__ ((noreturn)) void f() {
+  exit(0);
+}