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Optimize bytes.replace(b'', b'.') 

Issue #26574: Optimize bytes.replace(b'', b'.') and
bytearray.replace(b'', b'.'): up to 80% faster. Patch written by Josh Snider.
This commit is contained in:
Victor Stinner 2016-03-21 10:38:58 +01:00
parent 51b846c47a
commit fac395681f
5 changed files with 45 additions and 18 deletions
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3
Doc/whatsnew/3.6.rst
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@ -339,6 +339,9 @@ Optimizations
* Optimize :meth:`bytes.fromhex` and :meth:`bytearray.fromhex`: they are now
between 2x and 3.5x faster. (Contributed by Victor Stinner in :issue:`25401`).
* Optimize ``bytes.replace(b'', b'.')`` and ``bytearray.replace(b'', b'.')``:
up to 80% faster. (Contributed by Josh Snider in :issue:`26574`).
Build and C API Changes
=======================

1
Misc/ACKS
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@ -1376,6 +1376,7 @@ Mark Smith
Roy Smith
Ryan Smith-Roberts
Rafal Smotrzyk
Josh Snider
Eric Snow
Dirk Soede
Nir Soffer

3
Misc/NEWS
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@ -10,6 +10,9 @@ Release date: tba
Core and Builtins
-----------------
- Issue #26574: Optimize ``bytes.replace(b'', b'.')`` and
``bytearray.replace(b'', b'.')``. Patch written by Josh Snider.
- Issue #26581: If coding cookie is specified multiple times on a line in
Python source code file, only the first one is taken to account.

28
Objects/bytearrayobject.c
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@ -1705,17 +1705,27 @@ replace_interleave(PyByteArrayObject *self,
self_s = PyByteArray_AS_STRING(self);
result_s = PyByteArray_AS_STRING(result);
/* TODO: special case single character, which doesn't need memcpy */
/* Lay the first one down (guaranteed this will occur) */
Py_MEMCPY(result_s, to_s, to_len);
result_s += to_len;
count -= 1;
for (i=0; i<count; i++) {
*result_s++ = *self_s++;
if (to_len > 1) {
/* Lay the first one down (guaranteed this will occur) */
Py_MEMCPY(result_s, to_s, to_len);
result_s += to_len;
count -= 1;
for (i = 0; i < count; i++) {
*result_s++ = *self_s++;
Py_MEMCPY(result_s, to_s, to_len);
result_s += to_len;
}
}
else {
result_s[0] = to_s[0];
result_s += to_len;
count -= 1;
for (i = 0; i < count; i++) {
*result_s++ = *self_s++;
result_s[0] = to_s[0];
result_s += to_len;
}
}
/* Copy the rest of the original string */

28
Objects/bytesobject.c
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@ -2464,17 +2464,27 @@ replace_interleave(PyBytesObject *self,
self_s = PyBytes_AS_STRING(self);
result_s = PyBytes_AS_STRING(result);
/* TODO: special case single character, which doesn't need memcpy */
/* Lay the first one down (guaranteed this will occur) */
Py_MEMCPY(result_s, to_s, to_len);
result_s += to_len;
count -= 1;
for (i=0; i<count; i++) {
*result_s++ = *self_s++;
if (to_len > 1) {
/* Lay the first one down (guaranteed this will occur) */
Py_MEMCPY(result_s, to_s, to_len);
result_s += to_len;
count -= 1;
for (i = 0; i < count; i++) {
*result_s++ = *self_s++;
Py_MEMCPY(result_s, to_s, to_len);
result_s += to_len;
}
}
else {
result_s[0] = to_s[0];
result_s += to_len;
count -= 1;
for (i = 0; i < count; i++) {
*result_s++ = *self_s++;
result_s[0] = to_s[0];
result_s += to_len;
}
}
/* Copy the rest of the original string */