Index: lib/IR/Instructions.cpp
===================================================================
--- lib/IR/Instructions.cpp
+++ lib/IR/Instructions.cpp
@@ -331,6 +331,8 @@
 }
 
 bool CallInst::paramHasAttr(unsigned i, Attribute::AttrKind A) const {
+  assert(i < (getNumArgOperands() + 1) && "Param index out of bounds!");
+
   if (AttributeList.hasAttribute(i, A))
     return true;
   if (const Function *F = getCalledFunction())
@@ -575,6 +577,8 @@
 }
 
 bool InvokeInst::paramHasAttr(unsigned i, Attribute::AttrKind A) const {
+  assert(i < (getNumArgOperands() + 1) && "Param index out of bounds!");
+
   if (AttributeList.hasAttribute(i, A))
     return true;
   if (const Function *F = getCalledFunction())
Index: lib/Target/X86/X86FastISel.cpp
===================================================================
--- lib/Target/X86/X86FastISel.cpp
+++ lib/Target/X86/X86FastISel.cpp
@@ -2817,9 +2817,9 @@
   if (CC == CallingConv::Fast || CC == CallingConv::GHC ||
       CC == CallingConv::HiPE)
     return 0;
-  if (CS && !CS->paramHasAttr(1, Attribute::StructRet))
+  if (CS && !(CS->arg_size() != 0 && CS->paramHasAttr(1, Attribute::StructRet)))
     return 0;
-  if (CS && CS->paramHasAttr(1, Attribute::InReg))
+  if (CS && CS->arg_size() != 0 && CS->paramHasAttr(1, Attribute::InReg))
     return 0;
   return 4;
 }