Commit 63065d76 authored by Antoine Pitrou's avatar Antoine Pitrou

Issue #14624: UTF-16 decoding is now 3x to 4x faster on various inputs.

Patch by Serhiy Storchaka.
parent 12ea86ad
......@@ -10,6 +10,9 @@ What's New in Python 3.3.0 Alpha 4?
Core and Builtins
-----------------
- Issue #14624: UTF-16 decoding is now 3x to 4x faster on various inputs.
Patch by Serhiy Storchaka.
- asdl_seq and asdl_int_seq are now Py_ssize_t sized.
- Issue #14133 (PEP 415): Implement suppression of __context__ display with an
......
......@@ -215,7 +215,6 @@ InvalidContinuation:
goto Return;
}
#undef LONG_PTR_MASK
#undef ASCII_CHAR_MASK
......@@ -415,4 +414,152 @@ STRINGLIB(utf8_encoder)(PyObject *unicode,
#undef MAX_SHORT_UNICHARS
}
/* The pattern for constructing UCS2-repeated masks. */
#if SIZEOF_LONG == 8
# define UCS2_REPEAT_MASK 0x0001000100010001ul
#elif SIZEOF_LONG == 4
# define UCS2_REPEAT_MASK 0x00010001ul
#else
# error C 'long' size should be either 4 or 8!
#endif
/* The mask for fast checking. */
#if STRINGLIB_SIZEOF_CHAR == 1
/* The mask for fast checking of whether a C 'long' contains a
non-ASCII or non-Latin1 UTF16-encoded characters. */
# define FAST_CHAR_MASK (UCS2_REPEAT_MASK * (0xFFFFu & ~STRINGLIB_MAX_CHAR))
#else
/* The mask for fast checking of whether a C 'long' may contain
UTF16-encoded surrogate characters. This is an efficient heuristic,
assuming that non-surrogate characters with a code point >= 0x8000 are
rare in most input.
*/
# define FAST_CHAR_MASK (UCS2_REPEAT_MASK * 0x8000u)
#endif
/* The mask for fast byte-swapping. */
#define STRIPPED_MASK (UCS2_REPEAT_MASK * 0x00FFu)
/* Swap bytes. */
#define SWAB(value) ((((value) >> 8) & STRIPPED_MASK) | \
(((value) & STRIPPED_MASK) << 8))
Py_LOCAL_INLINE(Py_UCS4)
STRINGLIB(utf16_decode)(const unsigned char **inptr, const unsigned char *e,
STRINGLIB_CHAR *dest, Py_ssize_t *outpos,
int native_ordering)
{
Py_UCS4 ch;
const unsigned char *aligned_end =
(const unsigned char *) ((size_t) e & ~LONG_PTR_MASK);
const unsigned char *q = *inptr;
STRINGLIB_CHAR *p = dest + *outpos;
/* Offsets from q for retrieving byte pairs in the right order. */
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
int ihi = !!native_ordering, ilo = !native_ordering;
#else
int ihi = !native_ordering, ilo = !!native_ordering;
#endif
--e;
while (q < e) {
Py_UCS4 ch2;
/* First check for possible aligned read of a C 'long'. Unaligned
reads are more expensive, better to defer to another iteration. */
if (!((size_t) q & LONG_PTR_MASK)) {
/* Fast path for runs of in-range non-surrogate chars. */
register const unsigned char *_q = q;
while (_q < aligned_end) {
unsigned long block = * (unsigned long *) _q;
if (native_ordering) {
/* Can use buffer directly */
if (block & FAST_CHAR_MASK)
break;
}
else {
/* Need to byte-swap */
if (block & SWAB(FAST_CHAR_MASK))
break;
#if STRINGLIB_SIZEOF_CHAR == 1
block >>= 8;
#else
block = SWAB(block);
#endif
}
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
# if SIZEOF_LONG == 4
p[0] = (STRINGLIB_CHAR)(block & 0xFFFFu);
p[1] = (STRINGLIB_CHAR)(block >> 16);
# elif SIZEOF_LONG == 8
p[0] = (STRINGLIB_CHAR)(block & 0xFFFFu);
p[1] = (STRINGLIB_CHAR)((block >> 16) & 0xFFFFu);
p[2] = (STRINGLIB_CHAR)((block >> 32) & 0xFFFFu);
p[3] = (STRINGLIB_CHAR)(block >> 48);
# endif
#else
# if SIZEOF_LONG == 4
p[0] = (STRINGLIB_CHAR)(block >> 16);
p[1] = (STRINGLIB_CHAR)(block & 0xFFFFu);
# elif SIZEOF_LONG == 8
p[0] = (STRINGLIB_CHAR)(block >> 48);
p[1] = (STRINGLIB_CHAR)((block >> 32) & 0xFFFFu);
p[2] = (STRINGLIB_CHAR)((block >> 16) & 0xFFFFu);
p[3] = (STRINGLIB_CHAR)(block & 0xFFFFu);
# endif
#endif
_q += SIZEOF_LONG;
p += SIZEOF_LONG / 2;
}
q = _q;
if (q >= e)
break;
}
ch = (q[ihi] << 8) | q[ilo];
q += 2;
if (!Py_UNICODE_IS_SURROGATE(ch)) {
#if STRINGLIB_SIZEOF_CHAR < 2
if (ch > STRINGLIB_MAX_CHAR)
/* Out-of-range */
goto Return;
#endif
*p++ = (STRINGLIB_CHAR)ch;
continue;
}
/* UTF-16 code pair: */
if (q >= e)
goto UnexpectedEnd;
if (!Py_UNICODE_IS_HIGH_SURROGATE(ch))
goto IllegalEncoding;
ch2 = (q[ihi] << 8) | q[ilo];
q += 2;
if (!Py_UNICODE_IS_LOW_SURROGATE(ch2))
goto IllegalSurrogate;
ch = Py_UNICODE_JOIN_SURROGATES(ch, ch2);
#if STRINGLIB_SIZEOF_CHAR < 4
/* Out-of-range */
goto Return;
#else
*p++ = (STRINGLIB_CHAR)ch;
#endif
}
ch = 0;
Return:
*inptr = q;
*outpos = p - dest;
return ch;
UnexpectedEnd:
ch = 1;
goto Return;
IllegalEncoding:
ch = 2;
goto Return;
IllegalSurrogate:
ch = 3;
goto Return;
}
#undef UCS2_REPEAT_MASK
#undef FAST_CHAR_MASK
#undef STRIPPED_MASK
#undef SWAB
#undef LONG_PTR_MASK
#endif /* STRINGLIB_IS_UNICODE */
......@@ -5195,25 +5195,6 @@ PyUnicode_DecodeUTF16(const char *s,
return PyUnicode_DecodeUTF16Stateful(s, size, errors, byteorder, NULL);
}
/* Two masks for fast checking of whether a C 'long' may contain
UTF16-encoded surrogate characters. This is an efficient heuristic,
assuming that non-surrogate characters with a code point >= 0x8000 are
rare in most input.
FAST_CHAR_MASK is used when the input is in native byte ordering,
SWAPPED_FAST_CHAR_MASK when the input is in byteswapped ordering.
*/
#if (SIZEOF_LONG == 8)
# define FAST_CHAR_MASK 0x8000800080008000L
# define SWAPPED_FAST_CHAR_MASK 0x0080008000800080L
# define STRIPPED_MASK 0x00FF00FF00FF00FFL
#elif (SIZEOF_LONG == 4)
# define FAST_CHAR_MASK 0x80008000L
# define SWAPPED_FAST_CHAR_MASK 0x00800080L
# define STRIPPED_MASK 0x00FF00FFL
#else
# error C 'long' size should be either 4 or 8!
#endif
PyObject *
PyUnicode_DecodeUTF16Stateful(const char *s,
Py_ssize_t size,
......@@ -5226,30 +5207,15 @@ PyUnicode_DecodeUTF16Stateful(const char *s,
Py_ssize_t endinpos;
Py_ssize_t outpos;
PyObject *unicode;
const unsigned char *q, *e, *aligned_end;
const unsigned char *q, *e;
int bo = 0; /* assume native ordering by default */
int native_ordering = 0;
int native_ordering;
const char *errmsg = "";
/* Offsets from q for retrieving byte pairs in the right order. */
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
int ihi = 1, ilo = 0;
#else
int ihi = 0, ilo = 1;
#endif
PyObject *errorHandler = NULL;
PyObject *exc = NULL;
/* Note: size will always be longer than the resulting Unicode
character count */
unicode = PyUnicode_New(size, 127);
if (!unicode)
return NULL;
if (size == 0)
return unicode;
outpos = 0;
q = (unsigned char *)s;
e = q + size - 1;
e = q + size;
if (byteorder)
bo = *byteorder;
......@@ -5258,155 +5224,98 @@ PyUnicode_DecodeUTF16Stateful(const char *s,
byte order setting accordingly. In native mode, the leading BOM
mark is skipped, in all other modes, it is copied to the output
stream as-is (giving a ZWNBSP character). */
if (bo == 0) {
if (size >= 2) {
const Py_UCS4 bom = (q[ihi] << 8) | q[ilo];
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
if (bom == 0xFEFF) {
q += 2;
bo = -1;
}
else if (bom == 0xFFFE) {
q += 2;
bo = 1;
}
#else
if (bom == 0xFEFF) {
q += 2;
bo = 1;
}
else if (bom == 0xFFFE) {
q += 2;
bo = -1;
}
#endif
if (bo == 0 && size >= 2) {
const Py_UCS4 bom = (q[1] << 8) | q[0];
if (bom == 0xFEFF) {
q += 2;
bo = -1;
}
else if (bom == 0xFFFE) {
q += 2;
bo = 1;
}
if (byteorder)
*byteorder = bo;
}
if (bo == -1) {
/* force LE */
ihi = 1;
ilo = 0;
}
else if (bo == 1) {
/* force BE */
ihi = 0;
ilo = 1;
if (q == e) {
if (consumed)
*consumed = size;
Py_INCREF(unicode_empty);
return unicode_empty;
}
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
native_ordering = ilo < ihi;
native_ordering = bo <= 0;
#else
native_ordering = ilo > ihi;
native_ordering = bo >= 0;
#endif
aligned_end = (const unsigned char *) ((size_t) e & ~LONG_PTR_MASK);
while (q < e) {
Py_UCS4 ch;
/* First check for possible aligned read of a C 'long'. Unaligned
reads are more expensive, better to defer to another iteration. */
if (!((size_t) q & LONG_PTR_MASK)) {
/* Fast path for runs of non-surrogate chars. */
register const unsigned char *_q = q;
/* Note: size will always be longer than the resulting Unicode
character count */
unicode = PyUnicode_New((e - q + 1) / 2, 127);
if (!unicode)
return NULL;
outpos = 0;
while (1) {
Py_UCS4 ch = 0;
if (e - q >= 2) {
int kind = PyUnicode_KIND(unicode);
void *data = PyUnicode_DATA(unicode);
while (_q < aligned_end) {
unsigned long block = * (unsigned long *) _q;
Py_UCS4 maxch;
if (native_ordering) {
/* Can use buffer directly */
if (block & FAST_CHAR_MASK)
break;
}
else {
/* Need to byte-swap */
if (block & SWAPPED_FAST_CHAR_MASK)
break;
block = ((block >> 8) & STRIPPED_MASK) |
((block & STRIPPED_MASK) << 8);
}
maxch = (Py_UCS2)(block & 0xFFFF);
#if SIZEOF_LONG == 8
ch = (Py_UCS2)((block >> 16) & 0xFFFF);
maxch = MAX_MAXCHAR(maxch, ch);
ch = (Py_UCS2)((block >> 32) & 0xFFFF);
maxch = MAX_MAXCHAR(maxch, ch);
ch = (Py_UCS2)(block >> 48);
maxch = MAX_MAXCHAR(maxch, ch);
#else
ch = (Py_UCS2)(block >> 16);
maxch = MAX_MAXCHAR(maxch, ch);
#endif
if (maxch > PyUnicode_MAX_CHAR_VALUE(unicode)) {
if (unicode_widen(&unicode, outpos, maxch) < 0)
goto onError;
kind = PyUnicode_KIND(unicode);
data = PyUnicode_DATA(unicode);
}
#ifdef BYTEORDER_IS_LITTLE_ENDIAN
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)(block & 0xFFFF));
#if SIZEOF_LONG == 8
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 16) & 0xFFFF));
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 32) & 0xFFFF));
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 48)));
#else
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)(block >> 16));
#endif
#else
#if SIZEOF_LONG == 8
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 48)));
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 32) & 0xFFFF));
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 16) & 0xFFFF));
#else
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)(block >> 16));
#endif
PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)(block & 0xFFFF));
#endif
_q += SIZEOF_LONG;
if (kind == PyUnicode_1BYTE_KIND) {
if (PyUnicode_IS_ASCII(unicode))
ch = asciilib_utf16_decode(&q, e,
PyUnicode_1BYTE_DATA(unicode), &outpos,
native_ordering);
else
ch = ucs1lib_utf16_decode(&q, e,
PyUnicode_1BYTE_DATA(unicode), &outpos,
native_ordering);
} else if (kind == PyUnicode_2BYTE_KIND) {
ch = ucs2lib_utf16_decode(&q, e,
PyUnicode_2BYTE_DATA(unicode), &outpos,
native_ordering);
} else {
assert(kind == PyUnicode_4BYTE_KIND);
ch = ucs4lib_utf16_decode(&q, e,
PyUnicode_4BYTE_DATA(unicode), &outpos,
native_ordering);
}
q = _q;
if (q >= e)
break;
}
ch = (q[ihi] << 8) | q[ilo];
q += 2;
if (!Py_UNICODE_IS_SURROGATE(ch)) {
switch (ch)
{
case 0:
/* remaining byte at the end? (size should be even) */
if (q == e || consumed)
goto End;
errmsg = "truncated data";
startinpos = ((const char *)q) - starts;
endinpos = ((const char *)e) - starts;
break;
/* The remaining input chars are ignored if the callback
chooses to skip the input */
case 1:
errmsg = "unexpected end of data";
startinpos = ((const char *)q) - 2 - starts;
endinpos = ((const char *)e) - starts;
break;
case 2:
errmsg = "illegal encoding";
startinpos = ((const char *)q) - 2 - starts;
endinpos = startinpos + 2;
break;
case 3:
errmsg = "illegal UTF-16 surrogate";
startinpos = ((const char *)q) - 4 - starts;
endinpos = startinpos + 2;
break;
default:
if (unicode_putchar(&unicode, &outpos, ch) < 0)
goto onError;
continue;
}
/* UTF-16 code pair: */
if (q > e) {
errmsg = "unexpected end of data";
startinpos = (((const char *)q) - 2) - starts;
endinpos = ((const char *)e) + 1 - starts;
goto utf16Error;
}
if (Py_UNICODE_IS_HIGH_SURROGATE(ch)) {
Py_UCS4 ch2 = (q[ihi] << 8) | q[ilo];
q += 2;
if (Py_UNICODE_IS_LOW_SURROGATE(ch2)) {
if (unicode_putchar(&unicode, &outpos,
Py_UNICODE_JOIN_SURROGATES(ch, ch2)) < 0)
goto onError;
continue;
}
else {
errmsg = "illegal UTF-16 surrogate";
startinpos = (((const char *)q)-4)-starts;
endinpos = startinpos+2;
goto utf16Error;
}
}
errmsg = "illegal encoding";
startinpos = (((const char *)q)-2)-starts;
endinpos = startinpos+2;
/* Fall through to report the error */
utf16Error:
if (unicode_decode_call_errorhandler(
errors,
&errorHandler,
......@@ -5421,33 +5330,8 @@ PyUnicode_DecodeUTF16Stateful(const char *s,
&outpos))
goto onError;
}
/* remaining byte at the end? (size should be even) */
if (e == q) {
if (!consumed) {
errmsg = "truncated data";
startinpos = ((const char *)q) - starts;
endinpos = ((const char *)e) + 1 - starts;
if (unicode_decode_call_errorhandler(
errors,
&errorHandler,
"utf16", errmsg,
&starts,
(const char **)&e,
&startinpos,
&endinpos,
&exc,
(const char **)&q,
&unicode,
&outpos))
goto onError;
/* The remaining input chars are ignored if the callback
chooses to skip the input */
}
}
if (byteorder)
*byteorder = bo;
End:
if (consumed)
*consumed = (const char *)q-starts;
......@@ -5466,9 +5350,6 @@ PyUnicode_DecodeUTF16Stateful(const char *s,
return NULL;
}
#undef FAST_CHAR_MASK
#undef SWAPPED_FAST_CHAR_MASK
PyObject *
_PyUnicode_EncodeUTF16(PyObject *str,
const char *errors,
......
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