vim-patch:9.1.1622: Patch v9.1.1432 causes performance regressions (#35288)

Problem:  Patch v9.1.1432 causes performance regressions
Solution: Revert "patch 9.1.1432: GTK GUI: Buffer menu does not handle
          unicode correctly" (Yee Cheng Chin).

This reverts commit 08896dd330c6dc8324618fde482db968e6f71088.

The previous change to support Unicode characters properly in the
buffers menu resorted to removing all buffer menus and re-add the
buffers after doing a sort, per each buffer addition. This was quite
slow because if Vim is trying to load in multiple buffers at once (e.g.
when loading a session) this scales in O(n^2) and Vim can freeze for
dozens of seconds when adding a few hundred buffers.

related: vim/vim#17405
related: vim/vim#17928
fixes: vim/vim#17897

cda0d17f59

Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>

runtime/menu.vim

@@ -2,7 +2,7 @@
 " You can also use this as a start for your own set of menus.
 "
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2025 Jun 04
+" Last Change:	2023 Aug 10
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " Note that ":an" (short for ":anoremenu") is often used to make a menu work
@@ -684,7 +684,12 @@ func s:BMAdd()
     if s:bmenu_count == &menuitems && s:bmenu_short == 0
       call s:BMShow()
     else
-      call s:BMRedraw()
+      let name = expand("<afile>")
+      let num = expand("<abuf>") + 0 " add zero to convert to a number type
+      if s:BMCanAdd(name, num)
+	call <SID>BMFilename(name, num)
+	let s:bmenu_count += 1
+      endif
     endif
   endif
 endfunc
@@ -726,16 +731,17 @@ func s:BMCanAdd(name, num)
 endfunc
 
 " Create the buffer menu (delete an existing one first).
-func s:BMShow()
+func s:BMShow(...)
   let s:bmenu_wait = 1
   let s:bmenu_short = 1
   let s:bmenu_count = 0
   let s:bmenu_items = {}
+  "
+  " get new priority, if exists
+  if a:0 == 1
+    let g:bmenu_priority = a:1
+  endif
 
-  call s:BMRedraw()
-endfunc
-
-func s:BMRedraw()
   " Remove old menu, if it exists; keep one entry to avoid a torn off menu to
   " disappear.  Use try/catch to avoid setting v:errmsg
   try | unmenu &Buffers | catch | endtry
@@ -755,30 +761,26 @@ func s:BMRedraw()
   unmenu &Buffers.Dummy
 
   " figure out how many buffers there are
-  let buffer_menu_items = []
   let buf = 1
   while buf <= bufnr('$')
-    let name = bufname(buf)
-    if s:BMCanAdd(name, buf)
-      call add(buffer_menu_items, [substitute(name, ".", '\L\0', ""), name, buf])
+    if s:BMCanAdd(bufname(buf), buf)
+      let s:bmenu_count = s:bmenu_count + 1
     endif
     let buf = buf + 1
   endwhile
-  let s:bmenu_count = len(buffer_menu_items)
-
   if s:bmenu_count <= &menuitems
     let s:bmenu_short = 0
   endif
 
   " iterate through buffer list, adding each buffer to the menu:
-  call sort(buffer_menu_items)
-
-  let i = 0
-  for menu_item in buffer_menu_items
-    call s:BMFilename(menu_item[1], menu_item[2], i)
-    let i += 1
-  endfor
-
+  let buf = 1
+  while buf <= bufnr('$')
+    let name = bufname(buf)
+    if s:BMCanAdd(name, buf)
+      call <SID>BMFilename(name, buf)
+    endif
+    let buf = buf + 1
+  endwhile
   let s:bmenu_wait = 0
   aug buffer_list
   au!
@@ -787,6 +789,21 @@ func s:BMRedraw()
   aug END
 endfunc
 
+func s:BMHash(name)
+  " Make name all upper case, so that chars are between 32 and 96
+  let nm = substitute(a:name, ".*", '\U\0', "")
+  if has("ebcdic")
+    " HACK: Replace all non alphabetics with 'Z'
+    "       Just to make it work for now.
+    let nm = substitute(nm, "[^A-Z]", 'Z', "g")
+    let sp = char2nr('A') - 1
+  else
+    let sp = char2nr(' ')
+  endif
+  " convert first six chars into a number for sorting:
+  return (char2nr(nm[0]) - sp) * 0x800000 + (char2nr(nm[1]) - sp) * 0x20000 + (char2nr(nm[2]) - sp) * 0x1000 + (char2nr(nm[3]) - sp) * 0x80 + (char2nr(nm[4]) - sp) * 0x20 + (char2nr(nm[5]) - sp)
+endfunc
+
 func s:BMHash2(name)
   let nm = substitute(a:name, ".", '\L\0', "")
   " Not exactly right for EBCDIC...
@@ -808,15 +825,16 @@ func s:BMHash2(name)
 endfunc
 
 " Insert a buffer name into the buffer menu.
-func s:BMFilename(name, num, index)
+func s:BMFilename(name, num)
   let munge = <SID>BMMunge(a:name, a:num)
+  let hash = <SID>BMHash(munge)
   if s:bmenu_short == 0
     let s:bmenu_items[a:num] = munge
-    let cmd = 'an ' .. g:bmenu_priority .. '.9999.' .. a:index .. ' &Buffers.' .. munge
+    let cmd = 'an ' . g:bmenu_priority . '.' . hash . ' &Buffers.' . munge
   else
     let menu_name = <SID>BMHash2(munge) . munge
     let s:bmenu_items[a:num] = menu_name
-    let cmd = 'an ' .. g:bmenu_priority .. '.9999.0.' .. a:index .. ' &Buffers.' .. menu_name
+    let cmd = 'an ' . g:bmenu_priority . '.' . hash . '.' . hash . ' &Buffers.' . menu_name
   endif
   " set 'cpo' to include the <CR>
   let cpo_save = &cpo

test/old/testdir/test_gui.vim

@@ -44,17 +44,4 @@ func Test_colorscheme()
   redraw!
 endfunc
 
-" Test that buffer names are shown at the end in the :Buffers menu
-func Test_Buffers_Menu()
-  doautocmd LoadBufferMenu VimEnter
-
-  let name = '天'
-  exe ':badd ' .. name
-  let nr = bufnr('$')
-
-  let cmd = printf(':amenu Buffers.%s\ (%d)', name, nr)
-  let menu = split(execute(cmd), '\n')[1]
-  call assert_match('^9999 '.. name, menu)
-endfunc
-
 " vim: shiftwidth=2 sts=2 expandtab