This fixes a crash I observed in issue #48708 where the LSR
pass tries to insert an instruction in a basic block with only a
catchswitch statement in there. This happens because the Phi node
being evaluated has two incoming values which are reference-equal
but different basic blocks.
If the basic block associated with the incoming value of the operand
being evaluated has an EHPad terminator LSR drops that in the check
just above the one I added. But if that incoming value is reference-
equal to another incoming value, RewriteForPhi ends up rewriting
both values, one of which can have an EHPad terminator and thus
hits the "Insertion point must be a normal instruction" assert in
This fix makes CollectLoopInvariantFixupsAndFormulae also ignore
cases where a reference-equal value has a basic block with an
EHPad, same as it already does in case the primary value has one.