Invalid LLVM IR for certain iteration pattern

[martinholters]

Reduced from the problem I've observed in #27434 (comment).

struct Iter end
Base.iterate(::Iter) = (1, nothing)
Base.iterate(::Iter, ::Any) = nothing

function foo()
    ind = 0
    for x in (1,)
        for y in Iter()
            ind += 1
        end
    end
end

code_llvm(foo, Tuple{})

gives

PHI node has multiple entries for the same basic block with different incoming values!
  %value_phi2 = phi i64 [ %36, %L11 ], [ %37, %L11 ], [ %value_phi, %L5.L13_crit_edge ]
label %L11
  %37 = load i64, i64* %8, align 8, !dbg !28, !tbaa !21
  %36 = load i64, i64* %8, align 8, !dbg !28, !tbaa !21
LLVM ERROR: Broken function found, compilation aborted!

Tentatively assigning @Keno whom I suspect to be the best one to fix this.