perf(extmarks): avoid unnecessary invalidations for virt_text (#27435)

Invalidation of most w_valid flags isn't needed when adding or removing
virtual text below cursor.

1 files changed, 70 insertions, 54 deletions

diff --git a/src/nvim/change.c b/src/nvim/change.c
index e01921a826..2db3d007d7 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -163,6 +163,71 @@ void changed_internal(buf_T *buf)
   need_maketitle = true;  // set window title later
 }
 
+/// Invalidate a window's w_valid flags and w_lines[] entries after changing lines.
+static void changed_lines_invalidate_win(win_T *wp, linenr_T lnum, colnr_T col, linenr_T lnume,
+                                         linenr_T xtra)
+{
+  // If the changed line is in a range of previously folded lines,
+  // compare with the first line in that range.
+  if (wp->w_cursor.lnum <= lnum) {
+    int i = find_wl_entry(wp, lnum);
+    if (i >= 0 && wp->w_cursor.lnum > wp->w_lines[i].wl_lnum) {
+      changed_line_abv_curs_win(wp);
+    }
+  }
+
+  if (wp->w_cursor.lnum > lnum) {
+    changed_line_abv_curs_win(wp);
+  } else if (wp->w_cursor.lnum == lnum && wp->w_cursor.col >= col) {
+    changed_cline_bef_curs(wp);
+  }
+  if (wp->w_botline >= lnum) {
+    // Assume that botline doesn't change (inserted lines make
+    // other lines scroll down below botline).
+    approximate_botline_win(wp);
+  }
+
+  // Check if any w_lines[] entries have become invalid.
+  // For entries below the change: Correct the lnums for inserted/deleted lines.
+  // Makes it possible to stop displaying after the change.
+  for (int i = 0; i < wp->w_lines_valid; i++) {
+    if (wp->w_lines[i].wl_valid) {
+      if (wp->w_lines[i].wl_lnum >= lnum) {
+        // Do not change wl_lnum at index zero, it is used to compare with w_topline.
+        // Invalidate it instead.
+        // If lines haven been inserted/deleted and the buffer has virt_lines,
+        // invalidate the line after the changed lines as some virt_lines may
+        // now be drawn above a different line.
+        if (i == 0 || wp->w_lines[i].wl_lnum < lnume
+            || (xtra != 0 && wp->w_lines[i].wl_lnum == lnume
+                && buf_meta_total(wp->w_buffer, kMTMetaLines) > 0)) {
+          // line included in change
+          wp->w_lines[i].wl_valid = false;
+        } else if (xtra != 0) {
+          // line below change
+          wp->w_lines[i].wl_lnum += xtra;
+          wp->w_lines[i].wl_lastlnum += xtra;
+        }
+      } else if (wp->w_lines[i].wl_lastlnum >= lnum) {
+        // change somewhere inside this range of folded lines,
+        // may need to be redrawn
+        wp->w_lines[i].wl_valid = false;
+      }
+    }
+  }
+}
+
+/// Line changed_lines_invalidate_win(), but for all windows displaying a buffer.
+void changed_lines_invalidate_buf(buf_T *buf, linenr_T lnum, colnr_T col, linenr_T lnume,
+                                  linenr_T xtra)
+{
+  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
+    if (wp->w_buffer == buf) {
+      changed_lines_invalidate_win(wp, lnum, col, lnume, xtra);
+    }
+  }
+}
+
 /// Common code for when a change was made.
 /// See changed_lines() for the arguments.
 /// Careful: may trigger autocommands that reload the buffer.
@@ -296,55 +361,7 @@ static void changed_common(buf_T *buf, linenr_T lnum, colnr_T col, linenr_T lnum
         wp->w_cline_folded = folded;
       }
 
-      // If the changed line is in a range of previously folded lines,
-      // compare with the first line in that range.
-      if (wp->w_cursor.lnum <= lnum) {
-        int i = find_wl_entry(wp, lnum);
-        if (i >= 0 && wp->w_cursor.lnum > wp->w_lines[i].wl_lnum) {
-          changed_line_abv_curs_win(wp);
-        }
-      }
-
-      if (wp->w_cursor.lnum > lnum) {
-        changed_line_abv_curs_win(wp);
-      } else if (wp->w_cursor.lnum == lnum && wp->w_cursor.col >= col) {
-        changed_cline_bef_curs(wp);
-      }
-      if (wp->w_botline >= lnum) {
-        // Assume that botline doesn't change (inserted lines make
-        // other lines scroll down below botline).
-        approximate_botline_win(wp);
-      }
-
-      // Check if any w_lines[] entries have become invalid.
-      // For entries below the change: Correct the lnums for
-      // inserted/deleted lines.  Makes it possible to stop displaying
-      // after the change.
-      for (int i = 0; i < wp->w_lines_valid; i++) {
-        if (wp->w_lines[i].wl_valid) {
-          if (wp->w_lines[i].wl_lnum >= lnum) {
-            // Do not change wl_lnum at index zero, it is used to
-            // compare with w_topline.  Invalidate it instead.
-            // If the buffer has virt_lines, invalidate the line
-            // after the changed lines as the virt_lines for a
-            // changed line may become invalid.
-            if (i == 0 || wp->w_lines[i].wl_lnum < lnume
-                || (wp->w_lines[i].wl_lnum == lnume
-                    && buf_meta_total(wp->w_buffer, kMTMetaLines) > 0)) {
-              // line included in change
-              wp->w_lines[i].wl_valid = false;
-            } else if (xtra != 0) {
-              // line below change
-              wp->w_lines[i].wl_lnum += xtra;
-              wp->w_lines[i].wl_lastlnum += xtra;
-            }
-          } else if (wp->w_lines[i].wl_lastlnum >= lnum) {
-            // change somewhere inside this range of folded lines,
-            // may need to be redrawn
-            wp->w_lines[i].wl_valid = false;
-          }
-        }
-      }
+      changed_lines_invalidate_win(wp, lnum, col, lnume, xtra);
 
       // Take care of side effects for setting w_topline when folds have
       // changed.  Esp. when the buffer was changed in another window.
@@ -488,13 +505,13 @@ void deleted_lines_mark(linenr_T lnum, int count)
 }
 
 /// Marks the area to be redrawn after a change.
-/// Consider also calling changed_line_display_buf().
+/// Consider also calling changed_lines_invalidate_buf().
 ///
 /// @param buf the buffer where lines were changed
 /// @param lnum first line with change
 /// @param lnume line below last changed line
 /// @param xtra number of extra lines (negative when deleting)
-void buf_redraw_changed_lines_later(buf_T *buf, linenr_T lnum, linenr_T lnume, linenr_T xtra)
+void changed_lines_redraw_buf(buf_T *buf, linenr_T lnum, linenr_T lnume, linenr_T xtra)
 {
   if (buf->b_mod_set) {
     // find the maximum area that must be redisplayed
@@ -542,7 +559,7 @@ void buf_redraw_changed_lines_later(buf_T *buf, linenr_T lnum, linenr_T lnume, l
 void changed_lines(buf_T *buf, linenr_T lnum, colnr_T col, linenr_T lnume, linenr_T xtra,
                    bool do_buf_event)
 {
-  buf_redraw_changed_lines_later(buf, lnum, lnume, xtra);
+  changed_lines_redraw_buf(buf, lnum, lnume, xtra);
 
   if (xtra == 0 && curwin->w_p_diff && curwin->w_buffer == buf && !diff_internal()) {
     // When the number of lines doesn't change then mark_adjust() isn't
@@ -555,8 +572,7 @@ void changed_lines(buf_T *buf, linenr_T lnum, colnr_T col, linenr_T lnume, linen
         redraw_later(wp, UPD_VALID);
         wlnum = diff_lnum_win(lnum, wp);
         if (wlnum > 0) {
-          buf_redraw_changed_lines_later(wp->w_buffer, wlnum,
-                                         lnume - lnum + wlnum, 0);
+          changed_lines_redraw_buf(wp->w_buffer, wlnum, lnume - lnum + wlnum, 0);
         }
       }
     }