From 292fc87fe2f1611e7c83a61796ab71db6a0f7d97 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Fri, 28 May 2010 04:33:42 +0000
Subject: [PATCH] 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 | 6 ++++++
 test/Other/lint.ll    | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/lib/Analysis/Lint.cpp b/lib/Analysis/Lint.cpp
index a031cbc65b5..8119debdaf1 100644
--- a/lib/Analysis/Lint.cpp
+++ b/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
diff --git a/test/Other/lint.ll b/test/Other/lint.ll
index 1f9efe3ad9a..d0d3c7e1863 100644
--- a/test/Other/lint.ll
+++ b/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
+}
-- 
2.34.1