Commit: patch 9.2.0140: file reading performance can be improved

[Christian Brabandt]

patch 9.2.0140: file reading performance can be improved

Commit: https://github.com/vim/vim/commit/2ca96b09d751c35189dd587d9b201e2aeb5559c0
Author: Yasuhiro Matsumoto <matt...@gmail.com>
Date: Wed Mar 11 20:18:26 2026 +0000

patch 9.2.0140: file reading performance can be improved

Problem: Reading large files is slow because UTF-8 validation and
newline scanning are performed byte-by-byte. Initial file
loading also triggers listener and channel processing.
Solution: Use memchr() for SIMD-optimized newline scanning, implement
word-at-a-time ASCII skipping during UTF-8 validation using a
bitmask, skip listener/netbeans/channel notifications
when the ML_APPEND_NEW flag is set during readfile()
(Yasuhiro Matsumoto).

closes: #19612

Co-authored-by: NRK <n...@disroot.org>
Signed-off-by: Yasuhiro Matsumoto <matt...@gmail.com>
Signed-off-by: Christian Brabandt <c...@256bit.org>

diff --git a/src/fileio.c b/src/fileio.c
index 0ba9905c3..8917a7e29 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -27,6 +27,10 @@
// Is there any system that doesn't have access()?
#define USE_MCH_ACCESS

+// Bitmask with 0x80 set in each byte of a long_u word, used to detect
+// non-ASCII bytes (high bit set) in multiple bytes at once.
+#define NONASCII_MASK (((long_u)-1 / 0xFF) * 0x80)
+
#if defined(__hpux) && !defined(HAVE_DIRFD)
# define dirfd(x) ((x)->__dd_fd)
# define HAVE_DIRFD
@@ -2056,11 +2060,27 @@ retry:
int incomplete_tail = FALSE;

// Reading UTF-8: Check if the bytes are valid UTF-8.
- for (p = ptr; ; ++p)
+ for (p = ptr; ; )
{
- int todo = (int)((ptr + size) - p);
+ int todo;
int l;

+ // Skip ASCII bytes quickly using word-at-a-time check.
+ {
+ char_u *ascii_end = ptr + size;
+ while (ascii_end - p >= (long)sizeof(long_u))
+ {
+ long_u word;
+ memcpy(&word, p, sizeof(long_u));
+ if (word & NONASCII_MASK)
+ break;
+ p += sizeof(long_u);
+ }
+ while (p < ascii_end && *p < 0x80)
+ ++p;
+ }
+
+ todo = (int)((ptr + size) - p);
if (todo <= 0)
break;
if (*p >= 0x80)
@@ -2109,14 +2129,17 @@ retry:
if (bad_char_behavior == BAD_DROP)
{
mch_memmove(p, p + 1, todo - 1);
- --p;
--size;
}
- else if (bad_char_behavior != BAD_KEEP)
- *p = bad_char_behavior;
+ else
+ {
+ if (bad_char_behavior != BAD_KEEP)
+ *p = bad_char_behavior;
+ ++p;
+ }
}
else
- p += l - 1;
+ p += l;
}
}
if (p < ptr + size && !incomplete_tail)
@@ -2255,73 +2278,101 @@ rewind_retry:
}
else
{
- --ptr;
- while (++ptr, --size >= 0)
+ // Use memchr() for SIMD-optimized newline scanning instead
+ // of scanning each byte individually.
+ char_u *end = ptr + size;
+
+ while (ptr < end)
{
- if ((c = *ptr) != NUL && c != NL) // catch most common case
- continue;
- if (c == NUL)
- *ptr = NL; // NULs are replaced by newlines!
- else
+ char_u *nl = (char_u *)memchr(ptr, NL, end - ptr);
+ char_u *nul_scan;
+
+ if (nl == NULL)
{
- if (skip_count == 0)
+ // No more newlines in buffer.
+ // Replace any NUL bytes with NL in remaining data.
+ while ((nul_scan = (char_u *)memchr(ptr, NUL,
+ end - ptr)) != NULL)
+ {
+ *nul_scan = NL;
+ ptr = nul_scan + 1;
+ }
+ ptr = end;
+ break;
+ }
+
+ // Replace NUL bytes with NL before the newline.
+ {
+ char_u *scan = ptr;
+ while ((nul_scan = (char_u *)memchr(scan, NUL,
+ nl - scan)) != NULL)
+ {
+ *nul_scan = NL;
+ scan = nul_scan + 1;
+ }
+ }
+
+ // Process the newline.
+ ptr = nl;
+ if (skip_count == 0)
+ {
+ *ptr = NUL; // end of line
+ len = (colnr_T)(ptr - line_start + 1);
+ if (fileformat == EOL_DOS)
{
- *ptr = NUL; // end of line
- len = (colnr_T)(ptr - line_start + 1);
- if (fileformat == EOL_DOS)
+ if (ptr > line_start && ptr[-1] == CAR)
{
- if (ptr > line_start && ptr[-1] == CAR)
- {
- // remove CR before NL
- ptr[-1] = NUL;
- --len;
- }
- /*
- * Reading in Dos format, but no CR-LF found!
- * When 'fileformats' includes "unix", delete all
- * the lines read so far and start all over again.
- * Otherwise give an error message later.
- */
- else if (ff_error != EOL_DOS)
- {
- if ( try_unix
- && !read_stdin
- && (read_buffer
- || vim_lseek(fd, (off_T)0L, SEEK_SET)
- == 0))
- {
- fileformat = EOL_UNIX;
- if (set_options)
- set_fileformat(EOL_UNIX, OPT_LOCAL);
- file_rewind = TRUE;
- keep_fileformat = TRUE;
- goto retry;
- }
- ff_error = EOL_DOS;
- }
+ // remove CR before NL
+ ptr[-1] = NUL;
+ --len;
}
- if (ml_append(lnum, line_start, len, newfile) == FAIL)
+ /*
+ * Reading in Dos format, but no CR-LF found!
+ * When 'fileformats' includes "unix", delete all
+ * the lines read so far and start all over again.
+ * Otherwise give an error message later.
+ */
+ else if (ff_error != EOL_DOS)
{
- error = TRUE;
- break;
+ if ( try_unix
+ && !read_stdin
+ && (read_buffer
+ || vim_lseek(fd, (off_T)0L, SEEK_SET)
+ == 0))
+ {
+ fileformat = EOL_UNIX;
+ if (set_options)
+ set_fileformat(EOL_UNIX, OPT_LOCAL);
+ file_rewind = TRUE;
+ keep_fileformat = TRUE;
+ goto retry;
+ }
+ ff_error = EOL_DOS;
}
+ }
+ if (ml_append(lnum, line_start, len, newfile) == FAIL)
+ {
+ error = TRUE;
+ break;
+ }
#ifdef FEAT_PERSISTENT_UNDO
- if (read_undo_file)
- sha256_update(&sha_ctx, line_start, len);
+ if (read_undo_file)
+ sha256_update(&sha_ctx, line_start, len);
#endif
- ++lnum;
- if (--read_count == 0)
- {
- error = TRUE; // break loop
- line_start = ptr; // nothing left to write
- break;
- }
+ ++lnum;
+ if (--read_count == 0)
+ {
+ error = TRUE; // break loop
+ line_start = ptr; // nothing left to write
+ break;
}
- else
- --skip_count;
- line_start = ptr + 1;
}
+ else
+ --skip_count;
+ line_start = ptr + 1;
+ ++ptr;
}
+ size = -1;
}
linerest = (long)(ptr - line_start);
ui_breakcheck();
diff --git a/src/memline.c b/src/memline.c
index 2d92aadb6..58824ad11 100644
--- a/src/memline.c
+++ b/src/memline.c
@@ -3472,7 +3472,7 @@ ml_append_int(
#endif

#ifdef FEAT_NETBEANS_INTG
- if (netbeans_active())
+ if (!(flags & ML_APPEND_NEW) && netbeans_active())
{
int line_len = (int)STRLEN(line);
if (line_len > 0)
@@ -3481,7 +3481,7 @@ ml_append_int(
}
#endif
#ifdef FEAT_JOB_CHANNEL
- if (buf->b_write_to_channel)
+ if (!(flags & ML_APPEND_NEW) && buf->b_write_to_channel)
channel_write_new_lines(buf);
#endif
ret = OK;
@@ -3512,11 +3512,15 @@ ml_append_flush(
ml_flush_line(buf);

#ifdef FEAT_EVAL
- // When inserting above recorded changes: flush the changes before changing
- // the text. Then flush the cached line, it may become invalid.
- may_invoke_listeners(buf, lnum + 1, lnum + 1, 1);
- if (buf->b_ml.ml_line_lnum != 0)
- ml_flush_line(buf);
+ if (!(flags & ML_APPEND_NEW))
+ {
+ // When inserting above recorded changes: flush the changes before
+ // changing the text. Then flush the cached line, it may become
+ // invalid. Skip during initial file read for performance.
+ may_invoke_listeners(buf, lnum + 1, lnum + 1, 1);
+ if (buf->b_ml.ml_line_lnum != 0)
+ ml_flush_line(buf);
+ }
#endif

return ml_append_int(buf, lnum, line, len, flags);
diff --git a/src/version.c b/src/version.c
index ad7d6ab32..8c1f6c30a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -734,6 +734,8 @@ static char *(features[]) =

static int included_patches[] =
{ /* Add new patch number below this line */
+/**/
+ 140,
/**/
139,
/**/