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gh-93033: Use wmemchr in stringlib (GH-93034) 

Generally comparable perf for the "good" case where memchr doesn't
return any collisions (false matches on lower byte) but clearly faster
with collisions.
This commit is contained in:
goldsteinn 2022-05-23 20:45:31 -05:00 committed by GitHub
parent f7fabae75c
commit 7108bdf27c
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GPG Key ID: 4AEE18F83AFDEB23
11 changed files with 39 additions and 14 deletions
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1
Misc/NEWS.d/next/Library/2022-05-22-23-46-18.gh-issue-93033.wZfiL-.rst Normal file
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@ -0,0 +1 @@
Search in some strings (platform dependent i.e [U+0xFFFF, U+0x0100] on Windows or [U+0xFFFFFFFF, U+0x00010000] on Linux 64-bit) are now up to 10 times faster.

1
Objects/bytearrayobject.c
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@ -1096,6 +1096,7 @@ bytearray_dealloc(PyByteArrayObject *self)
#define STRINGLIB_ISSPACE Py_ISSPACE
#define STRINGLIB_ISLINEBREAK(x) ((x == '\n') || (x == '\r'))
#define STRINGLIB_CHECK_EXACT PyByteArray_CheckExact
#define STRINGLIB_FAST_MEMCHR memchr
#define STRINGLIB_MUTABLE 1
#include "stringlib/fastsearch.h"

1
Objects/bytes_methods.c
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@ -431,6 +431,7 @@ _Py_bytes_maketrans(Py_buffer *frm, Py_buffer *to)
#define STRINGLIB(F) stringlib_##F
#define STRINGLIB_CHAR char
#define STRINGLIB_SIZEOF_CHAR 1
#define STRINGLIB_FAST_MEMCHR memchr
#include "stringlib/fastsearch.h"
#include "stringlib/count.h"

1
Objects/stringlib/asciilib.h
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@ -21,6 +21,7 @@
#define STRINGLIB_CHECK PyUnicode_Check
#define STRINGLIB_CHECK_EXACT PyUnicode_CheckExact
#define STRINGLIB_MUTABLE 0
#define STRINGLIB_FAST_MEMCHR memchr
#define STRINGLIB_TOSTR PyObject_Str
#define STRINGLIB_TOASCII PyObject_ASCII

34
Objects/stringlib/fastsearch.h
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@ -39,7 +39,7 @@
#define STRINGLIB_BLOOM(mask, ch) \
((mask & (1UL << ((ch) & (STRINGLIB_BLOOM_WIDTH -1)))))
#if STRINGLIB_SIZEOF_CHAR == 1
#ifdef STRINGLIB_FAST_MEMCHR
# define MEMCHR_CUT_OFF 15
#else
# define MEMCHR_CUT_OFF 40
@ -53,8 +53,8 @@ STRINGLIB(find_char)(const STRINGLIB_CHAR* s, Py_ssize_t n, STRINGLIB_CHAR ch)
p = s;
e = s + n;
if (n > MEMCHR_CUT_OFF) {
#if STRINGLIB_SIZEOF_CHAR == 1
p = memchr(s, ch, n);
#ifdef STRINGLIB_FAST_MEMCHR
p = STRINGLIB_FAST_MEMCHR(s, ch, n);
if (p != NULL)
return (p - s);
return -1;
@ -102,16 +102,26 @@ STRINGLIB(find_char)(const STRINGLIB_CHAR* s, Py_ssize_t n, STRINGLIB_CHAR ch)
return -1;
}
#undef MEMCHR_CUT_OFF
#if STRINGLIB_SIZEOF_CHAR == 1
# define MEMRCHR_CUT_OFF 15
#else
# define MEMRCHR_CUT_OFF 40
#endif
Py_LOCAL_INLINE(Py_ssize_t)
STRINGLIB(rfind_char)(const STRINGLIB_CHAR* s, Py_ssize_t n, STRINGLIB_CHAR ch)
{
const STRINGLIB_CHAR *p;
#ifdef HAVE_MEMRCHR
/* memrchr() is a GNU extension, available since glibc 2.1.91.
it doesn't seem as optimized as memchr(), but is still quite
faster than our hand-written loop below */
/* memrchr() is a GNU extension, available since glibc 2.1.91. it
doesn't seem as optimized as memchr(), but is still quite
faster than our hand-written loop below. There is no wmemrchr
for 4-byte chars. */
if (n > MEMCHR_CUT_OFF) {
if (n > MEMRCHR_CUT_OFF) {
#if STRINGLIB_SIZEOF_CHAR == 1
p = memrchr(s, ch, n);
if (p != NULL)
@ -139,11 +149,11 @@ STRINGLIB(rfind_char)(const STRINGLIB_CHAR* s, Py_ssize_t n, STRINGLIB_CHAR ch)
if (*p == ch)
return n;
/* False positive */
if (n1 - n > MEMCHR_CUT_OFF)
if (n1 - n > MEMRCHR_CUT_OFF)
continue;
if (n <= MEMCHR_CUT_OFF)
if (n <= MEMRCHR_CUT_OFF)
break;
s1 = p - MEMCHR_CUT_OFF;
s1 = p - MEMRCHR_CUT_OFF;
while (p > s1) {
p--;
if (*p == ch)
@ -151,7 +161,7 @@ STRINGLIB(rfind_char)(const STRINGLIB_CHAR* s, Py_ssize_t n, STRINGLIB_CHAR ch)
}
n = p - s;
}
while (n > MEMCHR_CUT_OFF);
while (n > MEMRCHR_CUT_OFF);
}
#endif
}
@ -165,7 +175,7 @@ STRINGLIB(rfind_char)(const STRINGLIB_CHAR* s, Py_ssize_t n, STRINGLIB_CHAR ch)
return -1;
}
#undef MEMCHR_CUT_OFF
#undef MEMRCHR_CUT_OFF
/* Change to a 1 to see logging comments walk through the algorithm. */
#if 0 && STRINGLIB_SIZEOF_CHAR == 1

4
Objects/stringlib/replace.h
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@ -29,9 +29,9 @@ STRINGLIB(replace_1char_inplace)(STRINGLIB_CHAR* s, STRINGLIB_CHAR* end,
if (!--attempts) {
/* if u1 was not found for attempts iterations,
use FASTSEARCH() or memchr() */
#if STRINGLIB_SIZEOF_CHAR == 1
#ifdef STRINGLIB_FAST_MEMCHR
s++;
s = memchr(s, u1, end - s);
s = STRINGLIB_FAST_MEMCHR(s, u1, end - s);
if (s == NULL)
return;
#else

1
Objects/stringlib/stringdefs.h
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@ -24,4 +24,5 @@
#define STRINGLIB_CHECK_EXACT PyBytes_CheckExact
#define STRINGLIB_TOSTR PyObject_Str
#define STRINGLIB_TOASCII PyObject_Repr
#define STRINGLIB_FAST_MEMCHR memchr
#endif /* !STRINGLIB_STRINGDEFS_H */

1
Objects/stringlib/ucs1lib.h
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@ -20,6 +20,7 @@
#define STRINGLIB_NEW _PyUnicode_FromUCS1
#define STRINGLIB_CHECK PyUnicode_Check
#define STRINGLIB_CHECK_EXACT PyUnicode_CheckExact
#define STRINGLIB_FAST_MEMCHR memchr
#define STRINGLIB_MUTABLE 0
#define STRINGLIB_TOSTR PyObject_Str

4
Objects/stringlib/ucs2lib.h
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@ -21,6 +21,10 @@
#define STRINGLIB_CHECK PyUnicode_Check
#define STRINGLIB_CHECK_EXACT PyUnicode_CheckExact
#define STRINGLIB_MUTABLE 0
#if SIZEOF_WCHAR_T == 2
#define STRINGLIB_FAST_MEMCHR(s, c, n) \
(Py_UCS2 *)wmemchr((const wchar_t *)(s), c, n)
#endif
#define STRINGLIB_TOSTR PyObject_Str
#define STRINGLIB_TOASCII PyObject_ASCII

4
Objects/stringlib/ucs4lib.h
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@ -21,6 +21,10 @@
#define STRINGLIB_CHECK PyUnicode_Check
#define STRINGLIB_CHECK_EXACT PyUnicode_CheckExact
#define STRINGLIB_MUTABLE 0
#if SIZEOF_WCHAR_T == 4
#define STRINGLIB_FAST_MEMCHR(s, c, n) \
(Py_UCS4 *)wmemchr((const wchar_t *)(s), c, n)
#endif
#define STRINGLIB_TOSTR PyObject_Str
#define STRINGLIB_TOASCII PyObject_ASCII

1
Objects/stringlib/undef.h
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@ -8,3 +8,4 @@
#undef STRINGLIB_NEW
#undef STRINGLIB_IS_UNICODE
#undef STRINGLIB_MUTABLE
#undef STRINGLIB_FAST_MEMCHR