Add a lint check for returning the address of stack memory.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104936 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/Lint.cpp

@@ -310,6 +310,12 @@ void Lint::visitReturnInst(ReturnInst &I) {
   Assert1(!F->doesNotReturn(),
           "Unusual: Return statement in function with noreturn attribute",
           &I);
+
+  if (Value *V = I.getReturnValue()) {
+    Value *Obj = V->getUnderlyingObject();
+    Assert1(!isa<AllocaInst>(Obj) && !isa<VAArgInst>(Obj),
+            "Unusual: Returning alloca or va_arg value", &I);
+  }
 }
 
 // TODO: Add a length argument and check that the reference is in bounds

test/Other/lint.ll

@@ -97,3 +97,10 @@ define void @use_tail(i8* %valist) {
   tail call void @tailcallee(i8* %s)
   ret void
 }
+
+; CHECK: Unusual: Returning alloca or va_arg value
+define i8* @return_local(i32 %n, i32 %m) {
+  %t = alloca i8, i32 %n
+  %s = getelementptr i8* %t, i32 %m
+  ret i8* %s
+}