inlining: Use tmeet on inserted PiNode types for extended lattices (

#54105)

For extended lattice elements, the type of the resulting PiNode can end
up imprecise when `tmeet(argextype(argex), mft) ⊑ mft`

That said, it's not entirely clear to me what our `IR_FLAG_REFINED`
obligations are in the first place. Are we supposed to mark any
statements that are widened past what inference would have seen? If so,
it seems like we fall far short of that.

base/compiler/ssair/inlining.jl

@@ -80,7 +80,7 @@ function ssa_inlining_pass!(ir::IRCode, state::InliningState, propagate_inbounds
     @timeit "analysis" todo = assemble_inline_todo!(ir, state)
     isempty(todo) && return ir
     # Do the actual inlining for every call we identified
-    @timeit "execution" ir = batch_inline!(ir, todo, propagate_inbounds, OptimizationParams(state.interp))
+    @timeit "execution" ir = batch_inline!(ir, todo, propagate_inbounds, state.interp)
     return ir
 end
 
@@ -522,7 +522,7 @@ assuming their order stays the same post-discovery in `ml_matches`.
 """
 function ir_inline_unionsplit!(compact::IncrementalCompact, idx::Int, argexprs::Vector{Any},
                                union_split::UnionSplit, boundscheck::Symbol,
-                               todo_bbs::Vector{Tuple{Int,Int}}, params::OptimizationParams)
+                               todo_bbs::Vector{Tuple{Int,Int}}, interp::AbstractInterpreter)
     (; fully_covered, atype, cases, bbs) = union_split
     stmt, typ, line = compact.result[idx][:stmt], compact.result[idx][:type], compact.result[idx][:line]
     join_bb = bbs[end]
@@ -565,8 +565,10 @@ function ir_inline_unionsplit!(compact::IncrementalCompact, idx::Int, argexprs::
                 (isa(argex, SSAValue) || isa(argex, Argument)) || continue
                 aft, mft = fieldtype(atype, i), fieldtype(mtype, i)
                 if !(aft <: mft)
+                    𝕃ₒ = optimizer_lattice(interp)
+                    narrowed_type = tmeet(𝕃ₒ, argextype(argex, compact), mft)
                     argexprs′[i] = insert_node_here!(compact,
-                        NewInstruction(PiNode(argex, mft), mft, line))
+                        NewInstruction(PiNode(argex, mft), narrowed_type, line))
                 end
             end
         end
@@ -605,7 +607,8 @@ function ir_inline_unionsplit!(compact::IncrementalCompact, idx::Int, argexprs::
     return insert_node_here!(compact, NewInstruction(pn, typ, line))
 end
 
-function batch_inline!(ir::IRCode, todo::Vector{Pair{Int,Any}}, propagate_inbounds::Bool, params::OptimizationParams)
+function batch_inline!(ir::IRCode, todo::Vector{Pair{Int,Any}}, propagate_inbounds::Bool, interp::AbstractInterpreter)
+    params = OptimizationParams(interp)
     # Compute the new CFG first (modulo statement ranges, which will be computed below)
     state = CFGInliningState(ir)
     for (idx, item) in todo
@@ -662,7 +665,7 @@ function batch_inline!(ir::IRCode, todo::Vector{Pair{Int,Any}}, propagate_inboun
                 if isa(item, InliningTodo)
                     compact.ssa_rename[old_idx] = ir_inline_item!(compact, idx, argexprs, item, boundscheck, state.todo_bbs)
                 elseif isa(item, UnionSplit)
-                    compact.ssa_rename[old_idx] = ir_inline_unionsplit!(compact, idx, argexprs, item, boundscheck, state.todo_bbs, params)
+                    compact.ssa_rename[old_idx] = ir_inline_unionsplit!(compact, idx, argexprs, item, boundscheck, state.todo_bbs, interp)
                 end
                 compact[idx] = nothing
                 refinish && finish_current_bb!(compact, 0)