[SimpleLoopUnswitch] Verify LoopInfo after turning guards to branches

SplitBlockAndInsertIfThen doesn't correctly update LoopInfo when called
with Unreachable=true, which is the case when we turn guards to branches
in SimpleLoopUnswitch.

This adds LoopInfo verification before returning from turnGuardIntoBranch.

llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp

@@ -2735,6 +2735,7 @@ static BranchInst *turnGuardIntoBranch(IntrinsicInst *GI, Loop &L,
       MSSAU->getMemorySSA()->verifyMemorySSA();
   }
 
+  LI.verify(DT);
   ++NumGuards;
   return CheckBI;
 }

llvm/test/Transforms/SimpleLoopUnswitch/guards.ll

@@ -2,6 +2,9 @@
 ; RUN: opt -passes='simple-loop-unswitch<nontrivial>' -simple-loop-unswitch-guards -S < %s | FileCheck %s
 ; RUN: opt -passes='loop-mssa(simple-loop-unswitch<nontrivial>),verify<loops>' -simple-loop-unswitch-guards  -verify-memoryssa -S < %s | FileCheck %s
 
+; XFAIL: *
+; REQUIRES: asserts
+
 declare void @llvm.experimental.guard(i1, ...)
 
 define void @test_simple_case(i1 %cond, i32 %N) {

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

@@ -7,6 +7,7 @@ declare ptr @pluto()
 declare void @llvm.experimental.guard(i1, ...)
 declare void @widget()
 
+; XFAIL: *
 ; REQUIRES: asserts
 
 define void @foo(ptr addrspace(1) %arg, i64 %arg1) personality ptr @pluto {