glibc/string/strcoll_l.c
Carlos O'Donell 87701a58e2 strcoll: Remove incorrect STRDIFF-based optimization (Bug 18589).
The optimization introduced in commit
f13c2a8dff, causes regressions in
sorting for languages that have digraphs that change sort order, like
cs_CZ which sorts ch between h and i.

My analysis shows the fast-forwarding optimization in STRCOLL advances
through a digraph while possibly stopping in the middle which results
in a subsequent skipping of the digraph and incorrect sorting. The
optimization is incorrect as implemented and because of that I'm
removing it for 2.23, and I will also commit this fix for 2.22 where
it was originally introduced.

This patch reverts the optimization, introduces a new bug-strcoll2.c
regression test that tests both cs_CZ.UTF-8 and da_DK.ISO-8859-1 and
ensures they sort one digraph each correctly. The optimization can't be
applied without regressing this test.

Checked on x86_64, bug-strcoll2.c fails without this patch and passes
after. This will also get a fix on 2.22 which has the same bug.
2015-10-08 16:41:45 -04:00

352 lines
9.4 KiB
C

/* Copyright (C) 1995-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Ulrich Drepper <drepper@gnu.org>, 1995.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <assert.h>
#include <langinfo.h>
#include <locale.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sys/param.h>
#ifndef STRING_TYPE
# define STRING_TYPE char
# define USTRING_TYPE unsigned char
# define STRCOLL __strcoll_l
# define STRCMP strcmp
# define WEIGHT_H "../locale/weight.h"
# define SUFFIX MB
# define L(arg) arg
#endif
#define CONCAT(a,b) CONCAT1(a,b)
#define CONCAT1(a,b) a##b
#include "../locale/localeinfo.h"
#include WEIGHT_H
/* Track status while looking for sequences in a string. */
typedef struct
{
int len; /* Length of the current sequence. */
size_t val; /* Position of the sequence relative to the
previous non-ignored sequence. */
size_t idxmax; /* Maximum index in sequences. */
size_t idxcnt; /* Current count of indices. */
size_t backw; /* Current Backward sequence index. */
size_t backw_stop; /* Index where the backward sequences stop. */
const USTRING_TYPE *us; /* The string. */
unsigned char rule; /* Saved rule for the first sequence. */
int32_t idx; /* Index to weight of the current sequence. */
int32_t save_idx; /* Save looked up index of a forward
sequence after the last backward
sequence. */
const USTRING_TYPE *back_us; /* Beginning of the backward sequence. */
} coll_seq;
/* Get next sequence. Traverse the string as required. */
static __always_inline void
get_next_seq (coll_seq *seq, int nrules, const unsigned char *rulesets,
const USTRING_TYPE *weights, const int32_t *table,
const USTRING_TYPE *extra, const int32_t *indirect,
int pass)
{
size_t val = seq->val = 0;
int len = seq->len;
size_t backw_stop = seq->backw_stop;
size_t backw = seq->backw;
size_t idxcnt = seq->idxcnt;
size_t idxmax = seq->idxmax;
int32_t idx = seq->idx;
const USTRING_TYPE *us = seq->us;
while (len == 0)
{
++val;
if (backw_stop != ~0ul)
{
/* There is something pushed. */
if (backw == backw_stop)
{
/* The last pushed character was handled. Continue
with forward characters. */
if (idxcnt < idxmax)
{
idx = seq->save_idx;
backw_stop = ~0ul;
}
else
{
/* Nothing anymore. The backward sequence ended with
the last sequence in the string. Note that len is
still zero. */
idx = 0;
break;
}
}
else
{
/* XXX Traverse BACKW sequences from the beginning of
BACKW_STOP to get the next sequence. Is ther a quicker way
to do this? */
size_t i = backw_stop;
us = seq->back_us;
while (i < backw)
{
int32_t tmp = findidx (table, indirect, extra, &us, -1);
idx = tmp & 0xffffff;
i++;
}
--backw;
us = seq->us;
}
}
else
{
backw_stop = idxmax;
int32_t prev_idx = idx;
while (*us != L('\0'))
{
int32_t tmp = findidx (table, indirect, extra, &us, -1);
unsigned char rule = tmp >> 24;
prev_idx = idx;
idx = tmp & 0xffffff;
idxcnt = idxmax++;
/* Save the rule for the first sequence. */
if (__glibc_unlikely (idxcnt == 0))
seq->rule = rule;
if ((rulesets[rule * nrules + pass]
& sort_backward) == 0)
/* No more backward characters to push. */
break;
++idxcnt;
}
if (backw_stop >= idxcnt)
{
/* No sequence at all or just one. */
if (idxcnt == idxmax || backw_stop > idxcnt)
/* Note that len is still zero. */
break;
backw_stop = ~0ul;
}
else
{
/* We pushed backward sequences. If the stream ended with the
backward sequence, then we process the last sequence we
found. Otherwise we process the sequence before the last
one since the last one was a forward sequence. */
seq->back_us = seq->us;
seq->us = us;
backw = idxcnt;
if (idxmax > idxcnt)
{
backw--;
seq->save_idx = idx;
idx = prev_idx;
}
if (backw > backw_stop)
backw--;
}
}
len = weights[idx++];
/* Skip over indices of previous levels. */
for (int i = 0; i < pass; i++)
{
idx += len;
len = weights[idx];
idx++;
}
}
/* Update the structure. */
seq->val = val;
seq->len = len;
seq->backw_stop = backw_stop;
seq->backw = backw;
seq->idxcnt = idxcnt;
seq->idxmax = idxmax;
seq->us = us;
seq->idx = idx;
}
/* Compare two sequences. */
static __always_inline int
do_compare (coll_seq *seq1, coll_seq *seq2, int position,
const USTRING_TYPE *weights)
{
int seq1len = seq1->len;
int seq2len = seq2->len;
size_t val1 = seq1->val;
size_t val2 = seq2->val;
int idx1 = seq1->idx;
int idx2 = seq2->idx;
int result = 0;
/* Test for position if necessary. */
if (position && val1 != val2)
{
result = val1 > val2 ? 1 : -1;
goto out;
}
/* Compare the two sequences. */
do
{
if (weights[idx1] != weights[idx2])
{
/* The sequences differ. */
result = weights[idx1] - weights[idx2];
goto out;
}
/* Increment the offsets. */
++idx1;
++idx2;
--seq1len;
--seq2len;
}
while (seq1len > 0 && seq2len > 0);
if (position && seq1len != seq2len)
result = seq1len - seq2len;
out:
seq1->len = seq1len;
seq2->len = seq2len;
seq1->idx = idx1;
seq2->idx = idx2;
return result;
}
int
STRCOLL (const STRING_TYPE *s1, const STRING_TYPE *s2, __locale_t l)
{
struct __locale_data *current = l->__locales[LC_COLLATE];
uint_fast32_t nrules = current->values[_NL_ITEM_INDEX (_NL_COLLATE_NRULES)].word;
/* We don't assign the following values right away since it might be
unnecessary in case there are no rules. */
const unsigned char *rulesets;
const int32_t *table;
const USTRING_TYPE *weights;
const USTRING_TYPE *extra;
const int32_t *indirect;
if (nrules == 0)
return STRCMP (s1, s2);
/* Catch empty strings. */
if (__glibc_unlikely (*s1 == '\0') || __glibc_unlikely (*s2 == '\0'))
return (*s1 != '\0') - (*s2 != '\0');
rulesets = (const unsigned char *)
current->values[_NL_ITEM_INDEX (_NL_COLLATE_RULESETS)].string;
table = (const int32_t *)
current->values[_NL_ITEM_INDEX (CONCAT(_NL_COLLATE_TABLE,SUFFIX))].string;
weights = (const USTRING_TYPE *)
current->values[_NL_ITEM_INDEX (CONCAT(_NL_COLLATE_WEIGHT,SUFFIX))].string;
extra = (const USTRING_TYPE *)
current->values[_NL_ITEM_INDEX (CONCAT(_NL_COLLATE_EXTRA,SUFFIX))].string;
indirect = (const int32_t *)
current->values[_NL_ITEM_INDEX (CONCAT(_NL_COLLATE_INDIRECT,SUFFIX))].string;
assert (((uintptr_t) table) % __alignof__ (table[0]) == 0);
assert (((uintptr_t) weights) % __alignof__ (weights[0]) == 0);
assert (((uintptr_t) extra) % __alignof__ (extra[0]) == 0);
assert (((uintptr_t) indirect) % __alignof__ (indirect[0]) == 0);
int result = 0, rule = 0;
coll_seq seq1, seq2;
seq1.len = 0;
seq1.idxmax = 0;
seq1.rule = 0;
seq2.len = 0;
seq2.idxmax = 0;
for (int pass = 0; pass < nrules; ++pass)
{
seq1.idxcnt = 0;
seq1.idx = 0;
seq2.idx = 0;
seq1.backw_stop = ~0ul;
seq1.backw = ~0ul;
seq2.idxcnt = 0;
seq2.backw_stop = ~0ul;
seq2.backw = ~0ul;
/* We need the elements of the strings as unsigned values since they
are used as indices. */
seq1.us = (const USTRING_TYPE *) s1;
seq2.us = (const USTRING_TYPE *) s2;
/* We assume that if a rule has defined `position' in one section
this is true for all of them. Please note that the localedef programs
makes sure that `position' is not used at the first level. */
int position = rulesets[rule * nrules + pass] & sort_position;
while (1)
{
get_next_seq (&seq1, nrules, rulesets, weights, table,
extra, indirect, pass);
get_next_seq (&seq2, nrules, rulesets, weights, table,
extra, indirect, pass);
/* See whether any or both strings are empty. */
if (seq1.len == 0 || seq2.len == 0)
{
if (seq1.len == seq2.len)
{
/* Both strings ended and are equal at this level. Do a
byte-level comparison to ensure that we don't waste time
going through multiple passes for totally equal strings
before proceeding to subsequent passes. */
if (pass == 0 && STRCMP (s1, s2) == 0)
return result;
else
break;
}
/* This means one string is shorter than the other. Find out
which one and return an appropriate value. */
return seq1.len == 0 ? -1 : 1;
}
result = do_compare (&seq1, &seq2, position, weights);
if (result != 0)
return result;
}
rule = seq1.rule;
}
return result;
}
libc_hidden_def (STRCOLL)
#ifndef WIDE_CHAR_VERSION
weak_alias (__strcoll_l, strcoll_l)
#endif