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Faster non-destructive list sorting

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Postpone the creation of a new list to after sorting which turns out to
be a lot faster (1.1x - 1.5x speedup).

* src/fns.c (sort_list, sort_vector, Fsort):
Create the new list when moving the data out from the temporary array.
This commit is contained in:
Mattias Engdegård 2024-03-22 11:54:09 +01:00
parent deae311281
commit 45941a62c7
1 changed files with 35 additions and 30 deletions
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65
src/fns.c
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@ -2347,18 +2347,17 @@ See also the function `nreverse', which is used more often. */)
}
/* Stably sort LIST ordered by PREDICATE using the TIMSORT
algorithm. This converts the list to a vector, sorts the vector,
and returns the result converted back to a list. The input list
is destructively reused to hold the sorted result. */
/* Stably sort LIST ordered by PREDICATE and KEYFUNC, optionally reversed.
This converts the list to a vector, sorts the vector, and returns the
result converted back to a list. If INPLACE, the input list is
reused to hold the sorted result; otherwise a new list is returned. */
static Lisp_Object
sort_list (Lisp_Object list, Lisp_Object predicate, Lisp_Object keyfunc,
bool reverse)
bool reverse, bool inplace)
{
ptrdiff_t length = list_length (list);
if (length < 2)
return list;
return inplace ? list : list1 (XCAR (list));
else
{
Lisp_Object *result;
@ -2372,31 +2371,40 @@ sort_list (Lisp_Object list, Lisp_Object predicate, Lisp_Object keyfunc,
}
tim_sort (predicate, keyfunc, result, length, reverse);
ptrdiff_t i = 0;
tail = list;
while (CONSP (tail))
if (inplace)
{
XSETCAR (tail, result[i]);
tail = XCDR (tail);
i++;
/* Copy sorted vector contents back onto the original list. */
ptrdiff_t i = 0;
tail = list;
while (CONSP (tail))
{
XSETCAR (tail, result[i]);
tail = XCDR (tail);
i++;
}
}
else
{
/* Create a new list for the sorted vector contents. */
list = Qnil;
for (ptrdiff_t i = length - 1; i >= 0; i--)
list = Fcons (result[i], list);
}
SAFE_FREE ();
return list;
}
}
/* Stably sort VECTOR ordered by PREDICATE using the TIMSORT
algorithm. */
static void
/* Stably sort VECTOR in-place ordered by PREDICATE and KEYFUNC,
optionally reversed. */
static Lisp_Object
sort_vector (Lisp_Object vector, Lisp_Object predicate, Lisp_Object keyfunc,
bool reverse)
{
ptrdiff_t length = ASIZE (vector);
if (length < 2)
return;
tim_sort (predicate, keyfunc, XVECTOR (vector)->contents, length, reverse);
if (length >= 2)
tim_sort (predicate, keyfunc, XVECTOR (vector)->contents, length, reverse);
return vector;
}
DEFUN ("sort", Fsort, Ssort, 1, MANY, 0,
@ -2455,18 +2463,15 @@ usage: (sort SEQ &key KEY LESSP REVERSE IN-PLACE) */)
signal_error ("Invalid keyword argument", args[i]);
}
/* FIXME: for lists it may be slightly faster to make the copy after
sorting? Measure. */
if (!inplace)
seq = Fcopy_sequence (seq);
if (CONSP (seq))
seq = sort_list (seq, lessp, key, reverse);
return sort_list (seq, lessp, key, reverse, inplace);
else if (NILP (seq))
return seq;
else if (VECTORP (seq))
sort_vector (seq, lessp, key, reverse);
else if (!NILP (seq))
return sort_vector (inplace ? seq : Fcopy_sequence (seq),
lessp, key, reverse);
else
wrong_type_argument (Qlist_or_vector_p, seq);
return seq;
}
Lisp_Object