Add noreturn for exit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@77237 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/Builtins.def

@@ -54,6 +54,7 @@
 // of the function.  These must be kept in sync with the predicates in the
 // Builtin::Context class.  Currently we have:
 //  n -> nothrow
+//  r -> noreturn
 //  c -> const
 //  F -> this is a libc/libm function with a '__builtin_' prefix added.
 //  f -> this is a libc/libm function without the '__builtin_' prefix. It can
@@ -335,6 +336,9 @@ BUILTIN(__sync_fetch_and_umax, "UiUi*Ui", "n")
 // C99 library functions
 // C99 stdlib.h
 LIBBUILTIN(calloc, "v*zz",        "f",     "stdlib.h")
+LIBBUILTIN(exit, "vi",            "fr",    "stdlib.h")
+LIBBUILTIN(_Exit, "vi",           "fr",    "stdlib.h")
+LIBBUILTIN(_exit, "vi",           "fr",    "unistd.h")
 LIBBUILTIN(malloc, "v*z",         "f",     "stdlib.h")
 LIBBUILTIN(realloc, "v*v*z",      "f",     "stdlib.h")
 // C99 string.h

include/clang/Basic/Builtins.h

@@ -90,6 +90,11 @@ public:
     return strchr(GetRecord(ID).Attributes, 'n') != 0;
   }
   
+  /// isNoReturn - Return true if we know this builtin never returns.
+  bool isNoReturn(unsigned ID) const {
+    return strchr(GetRecord(ID).Attributes, 'r') != 0;
+  }
+  
   /// isLibFunction - Return true if this is a builtin for a libc/libm function,
   /// with a "__builtin_" prefix (e.g. __builtin_abs).
   bool isLibFunction(unsigned ID) const {

lib/Sema/SemaDecl.cpp

@@ -3676,6 +3676,9 @@ void Sema::AddKnownFunctionAttributes(FunctionDecl *FD) {
       if (!FD->getAttr<ConstAttr>())
         FD->addAttr(::new (Context) ConstAttr());
     }
+
+    if (Context.BuiltinInfo.isNoReturn(BuiltinID))
+      FD->addAttr(::new (Context) NoReturnAttr());
   }
 
   IdentifierInfo *Name = FD->getIdentifier();

test/Sema/return.c

@@ -191,3 +191,8 @@ int test27() {
 // PR4624
 void test28() __attribute__((noreturn));
 void test28(x) { while (1) { } }
+
+void exit(int);
+int test29() {
+  exit(1);
+}