refactor(signcol): smarter invalidation (#17533)

Previously b_signcols was invalidated whenever a sign was added/removed
or when a buffer line was added/removed.

This change introduces a sentinel linenr_T into the buffer state which
is a line number used to determine the signcolumn. With this
information, we can invalidate the signcolumn less often. Now the
signcolumn is only invalidated when a sign or line at the sentinel line
number is removed.

1 files changed, 4 insertions, 5 deletions

diff --git a/src/nvim/decoration.c b/src/nvim/decoration.c
index 6c006b7fe0..619e8fdadc 100644
--- a/src/nvim/decoration.c
+++ b/src/nvim/decoration.c
@@ -1,6 +1,7 @@
 // This is an open source non-commercial project. Dear PVS-Studio, please check
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
+#include "nvim/buffer.h"
 #include "nvim/decoration.h"
 #include "nvim/extmark.h"
 #include "nvim/highlight.h"
@@ -67,11 +68,6 @@ void bufhl_add_hl_pos_offset(buf_T *buf, int src_id, int hl_id, lpos_T pos_start
 void decor_redraw(buf_T *buf, int row1, int row2, Decoration *decor)
 {
   if (row2 >= row1) {
-    if (decor && decor->sign_text) {
-      buf->b_signcols_valid = false;
-      changed_line_abv_curs();
-    }
-
     if (!decor || decor->hl_id || decor_has_sign(decor)) {
       redraw_buf_range_later(buf, row1+1, row2+1);
     }
@@ -99,6 +95,9 @@ void decor_remove(buf_T *buf, int row, int row2, Decoration *decor)
       assert(buf->b_signs > 0);
       buf->b_signs--;
     }
+    if (row2 >= row && decor->sign_text) {
+      buf_signcols_del_check(buf, row+1, row2+1);
+    }
   }
   decor_free(decor);
 }