Use getsplit interface for InvokeCallInfo (#58328)

This makes invoke inlining work for CallInfo wrappers, e.g.
- JuliaComputing/DAECompiler.jl#23
- JuliaDebug/Cthulhu.jl#640

I think this is probably the cleanest way to do it. Other ways might be
to refactor InvokeCallInfo to wrap around a generic call info, but we
already have this interface for callinfos, so might as well try to use
it.

Author: Keno

Compiler/src/ssair/inlining.jl

@@ -1159,14 +1159,18 @@ function is_builtin(𝕃ₒ::AbstractLattice, s::Signature)
 end
 
 function handle_invoke_call!(todo::Vector{Pair{Int,Any}},
-    ir::IRCode, idx::Int, stmt::Expr, info::InvokeCallInfo, flag::UInt32,
+    ir::IRCode, idx::Int, stmt::Expr, @nospecialize(info), flag::UInt32,
     sig::Signature, state::InliningState)
-    match = info.match
+    nspl = nsplit(info)
+    nspl == 0 && return nothing # e.g. InvokeCICallInfo
+    @assert nspl == 1
+    mresult = getsplit(info, 1)
+    match = mresult.matches[1]
     if !match.fully_covers
         # TODO: We could union split out the signature check and continue on
         return nothing
     end
-    result = info.result
+    result = getresult(info, 1)
     if isa(result, ConcreteResult)
         item = concrete_result_item(result, info, state)
     elseif isa(result, SemiConcreteResult)
@@ -1648,7 +1652,7 @@ function assemble_inline_todo!(ir::IRCode, state::InliningState)
             handle_opaque_closure_call!(todo, ir, idx, stmt, info, flag, sig, state)
         elseif isa(info, ModifyOpInfo)
             handle_modifyop!_call!(ir, idx, stmt, info, state)
-        elseif isa(info, InvokeCallInfo)
+        elseif sig.f === Core.invoke
             handle_invoke_call!(todo, ir, idx, stmt, info, flag, sig, state)
         elseif isa(info, FinalizerInfo)
             handle_finalizer_call!(ir, idx, stmt, info, state)

Compiler/src/stmtinfo.jl

@@ -278,6 +278,7 @@ struct InvokeCICallInfo <: CallInfo
 end
 add_edges_impl(edges::Vector{Any}, info::InvokeCICallInfo) =
     add_inlining_edge!(edges, info.edge)
+nsplit_impl(info::InvokeCICallInfo) = 0
 
 """
     info::InvokeCallInfo
@@ -390,6 +391,11 @@ function add_inlining_edge!(edges::Vector{Any}, edge::CodeInstance)
     nothing
 end
 
+nsplit_impl(info::InvokeCallInfo) = 1
+getsplit_impl(info::InvokeCallInfo, idx::Int) = (@assert idx == 1; MethodLookupResult(Core.MethodMatch[info.match],
+    WorldRange(typemin(UInt), typemax(UInt)), false))
+getresult_impl(info::InvokeCallInfo, idx::Int) = (@assert idx == 1; info.result)
+
 
 """
     info::OpaqueClosureCallInfo