Fix a output marks performance regression (#19242)

An alternative approach for #18291. Improves perf by ~7%.

(cherry picked from commit 6b19d21)
Service-Card-Id: PVTI_lADOAF3p4s4AmhmQzgdm49Y
Service-Version: 1.22

Author: lhecker

src/buffer/out/Row.cpp

@@ -937,12 +937,12 @@ void ROW::_resizeChars(uint16_t colEndDirty, uint16_t chBegDirty, size_t chEndDi
     }
 }
 
-til::small_rle<TextAttribute, uint16_t, 1>& ROW::Attributes() noexcept
+RowAttributes& ROW::Attributes() noexcept
 {
     return _attr;
 }
 
-const til::small_rle<TextAttribute, uint16_t, 1>& ROW::Attributes() const noexcept
+const RowAttributes& ROW::Attributes() const noexcept
 {
     return _attr;
 }

src/buffer/out/Row.hpp

@@ -14,6 +14,11 @@
 class ROW;
 class TextBuffer;
 
+// Because MarkKind::Output gets set only on the actually written text,
+// most rows will end up having at least 2 runs: The start of the line
+// with MarkKind::Output and the rest of the line with MarkKind::None.
+using RowAttributes = til::small_rle<TextAttribute, uint16_t, 2>;
+
 enum class DelimiterClass
 {
     ControlChar,
@@ -148,8 +153,8 @@ class ROW final
     void ReplaceText(RowWriteState& state);
     void CopyTextFrom(RowCopyTextFromState& state);
 
-    til::small_rle<TextAttribute, uint16_t, 1>& Attributes() noexcept;
-    const til::small_rle<TextAttribute, uint16_t, 1>& Attributes() const noexcept;
+    RowAttributes& Attributes() noexcept;
+    const RowAttributes& Attributes() const noexcept;
     TextAttribute GetAttrByColumn(til::CoordType column) const;
     std::vector<uint16_t> GetHyperlinks() const;
     ImageSlice* SetImageSlice(ImageSlice::Pointer imageSlice) noexcept;
@@ -297,7 +302,7 @@ class ROW final
     std::span<uint16_t> _charOffsets;
     // _attr is a run-length-encoded vector of TextAttribute with a decompressed
     // length equal to _columnCount (= 1 TextAttribute per column).
-    til::small_rle<TextAttribute, uint16_t, 1> _attr;
+    RowAttributes _attr;
     // The width of the row in visual columns.
     uint16_t _columnCount = 0;
     // Stores double-width/height (DECSWL/DECDWL/DECDHL) attributes.