[BasicBlockUtils] Fixed LoopInfo update in UpdateAnalysisInformation() (#177147)
SplitLandingPadPredecessors() results in an irreducible loop
and makes LoopInfo invalid. Verification results in a crash:
Assertion `CB != OutsideLoopPreds[i] && "Loop has multiple entry
points!"' failed.
Created a new test with a broken LoopInfo after
SplitLandingPadPredecessors().
The test @split-lp-predecessors-test() after
SplitBlockPredecessors(catch_dest, { loop }, "", DT, LI) changes to
the following IR where the loop {%catch_dest} gets into irreducible
loop {%catch_dest.split-lp, %catch_dest}:
```
define void @split-lp-predecessors-test() personality ptr null {
entry:
invoke void @foo()
to label %loop unwind label %catch_dest.split-lp
loop: ; preds = %latch, %entry
invoke void @foo()
to label %latch unwind label %catch_dest1
latch: ; preds = %loop
br label %loop
catch_dest1: ; preds = %loop
%lpad = landingpad i32
cleanup
br label %catch_dest
catch_dest.split-lp: ; preds = %entry, %catch_dest
%lpad.split-lp = landingpad i32
cleanup
br label %catch_dest
catch_dest: ; preds = %catch_dest.split-lp, %catch_dest1
invoke void @foo()
to label %exit unwind label %catch_dest.split-lp
exit: ; preds = %catch_dest
ret void
}
```
Irreducible loops must be removed from LoopInfo.
When UpdateAnalysisInformation() detects an irreducible loop created
then the loop is erased from LoopInfo.
See the issue #163922 for details.
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