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Issue #14624: UTF-16 decoding is now 3x to 4x faster on various inputs.
Patch by Serhiy Storchaka.
This commit is contained in:
Antoine Pitrou
parent
12ea86adce
commit
63065d761e
3 changed files with 230 additions and 199 deletions
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@ -5195,25 +5195,6 @@ PyUnicode_DecodeUTF16(const char *s,
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return PyUnicode_DecodeUTF16Stateful(s, size, errors, byteorder, NULL);
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}
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/* Two masks for fast checking of whether a C 'long' may contain
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UTF16-encoded surrogate characters. This is an efficient heuristic,
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assuming that non-surrogate characters with a code point >= 0x8000 are
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rare in most input.
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FAST_CHAR_MASK is used when the input is in native byte ordering,
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SWAPPED_FAST_CHAR_MASK when the input is in byteswapped ordering.
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*/
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#if (SIZEOF_LONG == 8)
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# define FAST_CHAR_MASK 0x8000800080008000L
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# define SWAPPED_FAST_CHAR_MASK 0x0080008000800080L
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# define STRIPPED_MASK 0x00FF00FF00FF00FFL
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#elif (SIZEOF_LONG == 4)
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# define FAST_CHAR_MASK 0x80008000L
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# define SWAPPED_FAST_CHAR_MASK 0x00800080L
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# define STRIPPED_MASK 0x00FF00FFL
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#else
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# error C 'long' size should be either 4 or 8!
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#endif
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PyObject *
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PyUnicode_DecodeUTF16Stateful(const char *s,
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Py_ssize_t size,
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@ -5226,30 +5207,15 @@ PyUnicode_DecodeUTF16Stateful(const char *s,
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Py_ssize_t endinpos;
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Py_ssize_t outpos;
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PyObject *unicode;
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const unsigned char *q, *e, *aligned_end;
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const unsigned char *q, *e;
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int bo = 0; /* assume native ordering by default */
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int native_ordering = 0;
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int native_ordering;
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const char *errmsg = "";
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/* Offsets from q for retrieving byte pairs in the right order. */
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#ifdef BYTEORDER_IS_LITTLE_ENDIAN
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int ihi = 1, ilo = 0;
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#else
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int ihi = 0, ilo = 1;
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#endif
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PyObject *errorHandler = NULL;
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PyObject *exc = NULL;
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/* Note: size will always be longer than the resulting Unicode
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character count */
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unicode = PyUnicode_New(size, 127);
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if (!unicode)
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return NULL;
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if (size == 0)
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return unicode;
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outpos = 0;
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q = (unsigned char *)s;
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e = q + size - 1;
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e = q + size;
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if (byteorder)
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bo = *byteorder;
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@ -5258,155 +5224,98 @@ PyUnicode_DecodeUTF16Stateful(const char *s,
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byte order setting accordingly. In native mode, the leading BOM
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mark is skipped, in all other modes, it is copied to the output
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stream as-is (giving a ZWNBSP character). */
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if (bo == 0) {
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if (size >= 2) {
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const Py_UCS4 bom = (q[ihi] << 8) | q[ilo];
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#ifdef BYTEORDER_IS_LITTLE_ENDIAN
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if (bom == 0xFEFF) {
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q += 2;
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bo = -1;
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}
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else if (bom == 0xFFFE) {
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q += 2;
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bo = 1;
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}
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#else
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if (bom == 0xFEFF) {
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q += 2;
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bo = 1;
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}
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else if (bom == 0xFFFE) {
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q += 2;
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bo = -1;
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}
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#endif
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if (bo == 0 && size >= 2) {
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const Py_UCS4 bom = (q[1] << 8) | q[0];
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if (bom == 0xFEFF) {
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q += 2;
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bo = -1;
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}
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else if (bom == 0xFFFE) {
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q += 2;
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bo = 1;
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}
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if (byteorder)
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*byteorder = bo;
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}
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if (bo == -1) {
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/* force LE */
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ihi = 1;
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ilo = 0;
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}
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else if (bo == 1) {
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/* force BE */
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ihi = 0;
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ilo = 1;
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if (q == e) {
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if (consumed)
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*consumed = size;
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Py_INCREF(unicode_empty);
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return unicode_empty;
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}
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#ifdef BYTEORDER_IS_LITTLE_ENDIAN
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native_ordering = ilo < ihi;
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native_ordering = bo <= 0;
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#else
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native_ordering = ilo > ihi;
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native_ordering = bo >= 0;
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#endif
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aligned_end = (const unsigned char *) ((size_t) e & ~LONG_PTR_MASK);
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while (q < e) {
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Py_UCS4 ch;
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/* First check for possible aligned read of a C 'long'. Unaligned
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reads are more expensive, better to defer to another iteration. */
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if (!((size_t) q & LONG_PTR_MASK)) {
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/* Fast path for runs of non-surrogate chars. */
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register const unsigned char *_q = q;
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/* Note: size will always be longer than the resulting Unicode
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character count */
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unicode = PyUnicode_New((e - q + 1) / 2, 127);
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if (!unicode)
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return NULL;
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outpos = 0;
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while (1) {
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Py_UCS4 ch = 0;
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if (e - q >= 2) {
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int kind = PyUnicode_KIND(unicode);
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void *data = PyUnicode_DATA(unicode);
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while (_q < aligned_end) {
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unsigned long block = * (unsigned long *) _q;
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Py_UCS4 maxch;
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if (native_ordering) {
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/* Can use buffer directly */
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if (block & FAST_CHAR_MASK)
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break;
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}
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else {
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/* Need to byte-swap */
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if (block & SWAPPED_FAST_CHAR_MASK)
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break;
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block = ((block >> 8) & STRIPPED_MASK) |
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((block & STRIPPED_MASK) << 8);
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}
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maxch = (Py_UCS2)(block & 0xFFFF);
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#if SIZEOF_LONG == 8
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ch = (Py_UCS2)((block >> 16) & 0xFFFF);
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maxch = MAX_MAXCHAR(maxch, ch);
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ch = (Py_UCS2)((block >> 32) & 0xFFFF);
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maxch = MAX_MAXCHAR(maxch, ch);
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ch = (Py_UCS2)(block >> 48);
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maxch = MAX_MAXCHAR(maxch, ch);
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#else
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ch = (Py_UCS2)(block >> 16);
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maxch = MAX_MAXCHAR(maxch, ch);
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#endif
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if (maxch > PyUnicode_MAX_CHAR_VALUE(unicode)) {
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if (unicode_widen(&unicode, outpos, maxch) < 0)
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goto onError;
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kind = PyUnicode_KIND(unicode);
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data = PyUnicode_DATA(unicode);
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}
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#ifdef BYTEORDER_IS_LITTLE_ENDIAN
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)(block & 0xFFFF));
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#if SIZEOF_LONG == 8
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 16) & 0xFFFF));
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 32) & 0xFFFF));
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 48)));
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#else
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)(block >> 16));
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#endif
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#else
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#if SIZEOF_LONG == 8
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 48)));
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 32) & 0xFFFF));
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)((block >> 16) & 0xFFFF));
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#else
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)(block >> 16));
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#endif
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PyUnicode_WRITE(kind, data, outpos++, (Py_UCS2)(block & 0xFFFF));
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#endif
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_q += SIZEOF_LONG;
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if (kind == PyUnicode_1BYTE_KIND) {
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if (PyUnicode_IS_ASCII(unicode))
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ch = asciilib_utf16_decode(&q, e,
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PyUnicode_1BYTE_DATA(unicode), &outpos,
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native_ordering);
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else
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ch = ucs1lib_utf16_decode(&q, e,
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PyUnicode_1BYTE_DATA(unicode), &outpos,
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native_ordering);
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} else if (kind == PyUnicode_2BYTE_KIND) {
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ch = ucs2lib_utf16_decode(&q, e,
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PyUnicode_2BYTE_DATA(unicode), &outpos,
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native_ordering);
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} else {
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assert(kind == PyUnicode_4BYTE_KIND);
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ch = ucs4lib_utf16_decode(&q, e,
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PyUnicode_4BYTE_DATA(unicode), &outpos,
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native_ordering);
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}
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q = _q;
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if (q >= e)
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break;
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}
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ch = (q[ihi] << 8) | q[ilo];
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q += 2;
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if (!Py_UNICODE_IS_SURROGATE(ch)) {
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switch (ch)
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{
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case 0:
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/* remaining byte at the end? (size should be even) */
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if (q == e || consumed)
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goto End;
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errmsg = "truncated data";
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startinpos = ((const char *)q) - starts;
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endinpos = ((const char *)e) - starts;
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break;
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/* The remaining input chars are ignored if the callback
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chooses to skip the input */
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case 1:
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errmsg = "unexpected end of data";
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startinpos = ((const char *)q) - 2 - starts;
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endinpos = ((const char *)e) - starts;
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break;
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case 2:
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errmsg = "illegal encoding";
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startinpos = ((const char *)q) - 2 - starts;
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endinpos = startinpos + 2;
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break;
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case 3:
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errmsg = "illegal UTF-16 surrogate";
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startinpos = ((const char *)q) - 4 - starts;
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endinpos = startinpos + 2;
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break;
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default:
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if (unicode_putchar(&unicode, &outpos, ch) < 0)
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goto onError;
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continue;
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}
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/* UTF-16 code pair: */
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if (q > e) {
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errmsg = "unexpected end of data";
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startinpos = (((const char *)q) - 2) - starts;
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endinpos = ((const char *)e) + 1 - starts;
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goto utf16Error;
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}
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if (Py_UNICODE_IS_HIGH_SURROGATE(ch)) {
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Py_UCS4 ch2 = (q[ihi] << 8) | q[ilo];
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q += 2;
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if (Py_UNICODE_IS_LOW_SURROGATE(ch2)) {
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if (unicode_putchar(&unicode, &outpos,
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Py_UNICODE_JOIN_SURROGATES(ch, ch2)) < 0)
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goto onError;
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continue;
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}
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else {
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errmsg = "illegal UTF-16 surrogate";
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startinpos = (((const char *)q)-4)-starts;
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endinpos = startinpos+2;
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goto utf16Error;
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}
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}
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errmsg = "illegal encoding";
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startinpos = (((const char *)q)-2)-starts;
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endinpos = startinpos+2;
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/* Fall through to report the error */
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utf16Error:
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if (unicode_decode_call_errorhandler(
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errors,
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&errorHandler,
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@ -5421,33 +5330,8 @@ PyUnicode_DecodeUTF16Stateful(const char *s,
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&outpos))
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goto onError;
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}
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/* remaining byte at the end? (size should be even) */
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if (e == q) {
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if (!consumed) {
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errmsg = "truncated data";
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startinpos = ((const char *)q) - starts;
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endinpos = ((const char *)e) + 1 - starts;
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if (unicode_decode_call_errorhandler(
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errors,
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&errorHandler,
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"utf16", errmsg,
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&starts,
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(const char **)&e,
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&startinpos,
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&endinpos,
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&exc,
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(const char **)&q,
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&unicode,
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&outpos))
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goto onError;
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/* The remaining input chars are ignored if the callback
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chooses to skip the input */
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}
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}
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if (byteorder)
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*byteorder = bo;
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End:
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if (consumed)
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*consumed = (const char *)q-starts;
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@ -5466,9 +5350,6 @@ PyUnicode_DecodeUTF16Stateful(const char *s,
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return NULL;
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}
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#undef FAST_CHAR_MASK
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#undef SWAPPED_FAST_CHAR_MASK
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PyObject *
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_PyUnicode_EncodeUTF16(PyObject *str,
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const char *errors,
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