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perf: remove loop for computing last position in getvcol()

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The function computed the start of the multibyte character and iterated
until the current character reached this position. The loop at the start of the function
handed the case where the index passed to the function was past the end of the line.
This loop can be removed if the function instead compares the next position against
the end position end exits the loop if it is greater than the end position.
This commit is contained in:
VanaIgr 2023-12-13 13:54:28 -06:00
parent a9c551e5e3
commit 2f2f12122f
1 changed files with 9 additions and 21 deletions
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30
src/nvim/plines.c
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@ -493,7 +493,6 @@ static int virt_text_cursor_off(chartabsize_T *cts, bool on_NUL)
void getvcol(win_T *wp, pos_T *pos, colnr_T *start, colnr_T *cursor, colnr_T *end)
{
char *ptr; // points to current char
char *posptr; // points to char at pos->col
int incr;
int head;
colnr_T *vts = wp->w_buffer->b_p_vts_array;
@ -502,21 +501,10 @@ void getvcol(win_T *wp, pos_T *pos, colnr_T *start, colnr_T *cursor, colnr_T *en
colnr_T vcol = 0;
char *line = ptr = ml_get_buf(wp->w_buffer, pos->lnum); // start of the line
if (pos->col == MAXCOL) {
// continue until the NUL
posptr = NULL;
} else {
// In a few cases the position can be beyond the end of the line.
for (colnr_T i = 0; i < pos->col; i++) {
if (ptr[i] == NUL) {
pos->col = i;
break;
}
}
posptr = ptr + pos->col;
posptr -= utf_head_off(line, posptr);
uintptr_t last_pos = (uintptr_t)(ptr + pos->col);
if (last_pos < (uintptr_t)ptr) {
last_pos = UINTPTR_MAX; // unsigned overflow
}
chartabsize_T cts;
bool on_NUL = false;
init_chartabsize_arg(&cts, wp, pos->lnum, 0, line, line);
@ -566,13 +554,13 @@ void getvcol(win_T *wp, pos_T *pos, colnr_T *start, colnr_T *cursor, colnr_T *en
}
}
if ((posptr != NULL) && (ptr >= posptr)) {
// character at pos->col
char *const next = ptr + utfc_ptr2len(ptr);
if ((uintptr_t)next > last_pos) {
break;
}
ptr = next;
vcol += incr;
MB_PTR_ADV(ptr);
}
} else {
while (true) {
@ -589,13 +577,13 @@ void getvcol(win_T *wp, pos_T *pos, colnr_T *start, colnr_T *cursor, colnr_T *en
break;
}
if ((posptr != NULL) && (cts.cts_ptr >= posptr)) {
// character at pos->col
char *const next = cts.cts_ptr + utfc_ptr2len(cts.cts_ptr);
if ((uintptr_t)next > last_pos) {
break;
}
cts.cts_ptr = next;
cts.cts_vcol += incr;
MB_PTR_ADV(cts.cts_ptr);
}
vcol = cts.cts_vcol;
ptr = cts.cts_ptr;