[Test] Add test exposing crash in SimpleLoopUnswitch

The test crashes with an assert in unswitchNontrivialInvariants.

Author: d-makogon

llvm/test/Transforms/SimpleLoopUnswitch/nontrivial-unswitch-skip-selects-in-guards.ll

@@ -0,0 +1,36 @@
+; RUN: opt -passes='loop(simple-loop-unswitch<nontrivial>),verify<loops>' -S < %s | FileCheck %s
+; RUN: opt -passes='loop-mssa(simple-loop-unswitch<nontrivial>),verify<loops>' -S < %s | FileCheck %s
+; RUN: opt -simple-loop-unswitch -enable-nontrivial-unswitch -verify-memoryssa -S < %s | FileCheck %s
+
+declare ptr @pluto()
+declare void @llvm.experimental.guard(i1, ...)
+declare void @widget()
+
+; REQUIRES: asserts
+; XFAIL: *
+
+define void @foo(ptr addrspace(1) %arg, i64 %arg1) personality ptr @pluto {
+bb:
+  %tmp = icmp slt i32 poison, 570
+  %tmp2 = select i1 %tmp, i1 true, i1 false
+  br label %bb3
+
+bb3:                                              ; preds = %bb6, %bb
+  call void (i1, ...) @llvm.experimental.guard(i1 %tmp2, i32 7) [ "deopt"() ]
+  invoke void @widget()
+          to label %bb4 unwind label %bb7
+
+bb4:                                              ; preds = %bb3
+  invoke void @widget()
+          to label %bb6 unwind label %bb7
+
+bb6:                                              ; preds = %bb4
+  invoke void @widget()
+          to label %bb3 unwind label %bb7
+
+bb7:                                              ; preds = %bb6, %bb4, %bb3
+  %tmp8 = landingpad { ptr, i32 }
+          cleanup
+  ret void
+}
+