Make sure to preserve info in union-split (JuliaLang#47301)

Generally we try pretty hard in inlining to make sure to preserve
the :info of a statement when we turn it into :invoke. We don't
use this information in the compiler itself, but it is used
by external tools (including Cthulhu). However, we were dropping
this info during union splitting for no particular reason. Fix
that.

base/compiler/ssair/inlining.jl

@@ -35,6 +35,7 @@ end
 struct InvokeCase
  invoke::MethodInstance
  effects::Effects
+ info::CallInfo
 end
 
 struct InliningCase
@@ -592,7 +593,7 @@ function ir_inline_unionsplit!(compact::IncrementalCompact, idx::Int,
  elseif isa(case, InvokeCase)
  inst = Expr(:invoke, case.invoke, argexprs′...)
  flag = flags_for_effects(case.effects)
- val = insert_node_here!(compact, NewInstruction(inst, typ, NoCallInfo(), line, flag))
+ val = insert_node_here!(compact, NewInstruction(inst, typ, case.info, line, flag))
  else
  case = case::ConstantCase
  val = case.val
@@ -796,19 +797,19 @@ function rewrite_apply_exprargs!(todo::Vector{Pair{Int,Any}},
 end
 
 function compileable_specialization(match::MethodMatch, effects::Effects,
- et::InliningEdgeTracker; compilesig_invokes::Bool=true)
+ et::InliningEdgeTracker, @nospecialize(info::CallInfo); compilesig_invokes::Bool=true)
  mi = specialize_method(match; compilesig=compilesig_invokes)
  mi === nothing && return nothing
  add_inlining_backedge!(et, mi)
- return InvokeCase(mi, effects)
+ return InvokeCase(mi, effects, info)
 end
 
 function compileable_specialization(linfo::MethodInstance, effects::Effects,
- et::InliningEdgeTracker; compilesig_invokes::Bool=true)
+ et::InliningEdgeTracker, @nospecialize(info::CallInfo); compilesig_invokes::Bool=true)
  mi = specialize_method(linfo.def::Method, linfo.specTypes, linfo.sparam_vals; compilesig=compilesig_invokes)
  mi === nothing && return nothing
  add_inlining_backedge!(et, mi)
- return InvokeCase(mi, effects)
+ return InvokeCase(mi, effects, info)
 end
 
 compileable_specialization(result::InferenceResult, args...; kwargs...) = (@nospecialize;
@@ -862,7 +863,7 @@ function resolve_todo(mi::MethodInstance, result::Union{MethodMatch,InferenceRes
  # the duplicated check might have been done already within `analyze_method!`, but still
  # we need it here too since we may come here directly using a constant-prop' result
  if !state.params.inlining || is_stmt_noinline(flag)
- return compileable_specialization(result, effects, et;
+ return compileable_specialization(result, effects, et, info;
  compilesig_invokes=state.params.compilesig_invokes)
  end
 
@@ -877,7 +878,7 @@ function resolve_todo(mi::MethodInstance, result::Union{MethodMatch,InferenceRes
  return ConstantCase(quoted(src.val))
  end
 
- src === nothing && return compileable_specialization(result, effects, et;
+ src === nothing && return compileable_specialization(result, effects, et, info;
  compilesig_invokes=state.params.compilesig_invokes)
 
  add_inlining_backedge!(et, mi)
@@ -966,7 +967,7 @@ function analyze_method!(match::MethodMatch, argtypes::Vector{Any},
  mi = specialize_method(match; preexisting=true) # Union{Nothing, MethodInstance}
  if mi === nothing
  et = InliningEdgeTracker(state.et, invokesig)
- return compileable_specialization(match, Effects(), et;
+ return compileable_specialization(match, Effects(), et, info;
  compilesig_invokes=state.params.compilesig_invokes)
  end
 
@@ -1542,7 +1543,7 @@ function handle_modifyfield!_call!(ir::IRCode, idx::Int, stmt::Expr, info::Modif
  length(info.results) == 1 || return nothing
  match = info.results[1]::MethodMatch
  match.fully_covers || return nothing
- case = compileable_specialization(match, Effects(), InliningEdgeTracker(state.et);
+ case = compileable_specialization(match, Effects(), InliningEdgeTracker(state.et), info;
  compilesig_invokes=state.params.compilesig_invokes)
  case === nothing && return nothing
  stmt.head = :invoke_modify