1 files changed, 17 insertions, 8 deletions
diff --git a/llvm/lib/Analysis/Lint.cpp b/llvm/lib/Analysis/Lint.cpp
index ae92f502f5c..7b792ed0a2e 100644
--- a/llvm/lib/Analysis/Lint.cpp
+++ b/llvm/lib/Analysis/Lint.cpp
@@ -285,15 +285,24 @@ void Lint::visitCallSite(CallSite CS) {
     }
   }
 
-  if (CS.isCall() && cast<CallInst>(CS.getInstruction())->isTailCall())
-    for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
-         AI != AE; ++AI) {
-      Value *Obj = findValue(*AI, /*OffsetOk=*/true);
-      Assert(!isa<AllocaInst>(Obj),
-             "Undefined behavior: Call with \"tail\" keyword references "
-             "alloca",
-             &I);
+  if (CS.isCall()) {
+    const CallInst *CI = cast<CallInst>(CS.getInstruction());
+    if (CI->isTailCall()) {
+      const AttributeList &PAL = CI->getAttributes();
+      unsigned ArgNo = 0;
+      for (Value *Arg : CS.args()) {
+        // Skip ByVal arguments since they will be memcpy'd to the callee's
+        // stack anyway.
+        if (PAL.hasParamAttribute(ArgNo++, Attribute::ByVal))
+          continue;
+        Value *Obj = findValue(Arg, /*OffsetOk=*/true);
+        Assert(!isa<AllocaInst>(Obj),
+               "Undefined behavior: Call with \"tail\" keyword references "
+               "alloca",
+               &I);
+      }
     }
+  }
 
 
   if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I))