perf(loader): re-use topmod cache to find `setup()` module

lua/lazy/core/cache.lua

@@ -39,8 +39,8 @@ M.me = debug.getinfo(1, "S").source:sub(2)
 M.me = vim.fn.fnamemodify(M.me, ":p:h:h:h:h"):gsub("\\", "/")
 ---@type table<string, table<string,string>>
 M.topmods = { lazy = { [M.me] = M.me } }
----@type table<string, true>
-M.indexed = { [M.me] = true }
+---@type table<string, string[]>
+M.indexed = { [M.me] = { "lazy" } }
 M.indexed_unloaded = false
 M.indexed_rtp = 0
 -- selene:allow(global_usage)
@@ -219,7 +219,7 @@ function M._index(path)
     if not Util then
       return false
     end
-    M.indexed[path] = true
+    M.indexed[path] = {}
     Util.ls(path .. "/lua", function(_, name, t)
       local topname
       if name:sub(-4) == ".lua" then
@@ -230,6 +230,7 @@ function M._index(path)
       if topname then
         M.topmods[topname] = M.topmods[topname] or {}
         M.topmods[topname][path] = path
+        table.insert(M.indexed[path], topname)
       end
     end)
     return true
@@ -237,6 +238,11 @@ function M._index(path)
   return false
 end
 
+function M.get_topmods(path)
+  M._index(path)
+  return M.indexed[path] or {}
+end
+
 ---@param modname string
 ---@return string?
 function M.find(modname)

lua/lazy/core/loader.lua

@@ -1,6 +1,7 @@
 local Util = require("lazy.core.util")
 local Config = require("lazy.core.config")
 local Handler = require("lazy.core.handler")
+local Cache = require("lazy.core.cache")
 
 local M = {}
 
@@ -204,19 +205,17 @@ function M.config(plugin)
     end
   else
     local normname = Util.normname(plugin.name)
-    ---@type table<string, string>
+    ---@type string[]
     local mods = {}
-    Util.ls(plugin.dir .. "/lua", function(_, modname)
-      modname = modname:gsub("%.lua$", "")
-      mods[modname] = modname
+    for _, modname in ipairs(Cache.get_topmods(plugin.dir)) do
+      mods[#mods + 1] = modname
       local modnorm = Util.normname(modname)
       -- if we found an exact match, then use that
       if modnorm == normname then
         mods = { modname }
-        return false
+        break
+      end
     end
-    end)
-    mods = vim.tbl_values(mods)
     if #mods == 1 then
       fn = function()
         local opts = plugin.config