[X86][FastISel] Assert that we are dealing with arithmetic with overflow intrinsics. NFC

llvm-svn: 286961
diff --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index a6dbf75..1979433 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -2769,6 +2769,9 @@
     const Function *Callee = II->getCalledFunction();
     auto *Ty = cast<StructType>(Callee->getReturnType());
     Type *RetTy = Ty->getTypeAtIndex(0U);
+    assert(Ty->getTypeAtIndex(1)->isIntegerTy() &&
+           Ty->getTypeAtIndex(1)->getScalarSizeInBits() == 1 &&
+           "Overflow value expected to be an i1");
 
     MVT VT;
     if (!isTypeLegal(RetTy, VT))