PR9218: SimplifyDemandedVectorElts can return a non-null value that is not

the instruction passed in.  Make sure to account for this correctly, instead
of looping infinitely.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126058 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/2011-02-16-InsertelementHang.ll

@@ -0,0 +1,11 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+; PR9218
+
+%vec2x2 = type { <2 x double>, <2 x double> }
+
+define %vec2x2 @split(double) nounwind alwaysinline {
+; CHECK: @split
+; CHECK: ret %vec2x2 undef
+  %vba = insertelement <2 x double> undef, double %0, i32 2
+  ret <2 x double> %vba, <2 x double> %vba
+}