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Use Jenkins hash.
This is about twice as fast as the current hash, and removes the need for double hashing (improving locality of reference). The hash function is based on Bob Jenkins' design, slightly adapted wherever Make needs to hash NUL-terminated strings. The old hash function is kept for case-insensitive hashing. This saves 8.5% on QEMU's no-op build (from 12.87s to 11.78s). * configure.ac: Check endianness. * hash.c (rol32, jhash_mix, jhash_final, JHASH_INITVAL, sum_get_unaligned_32, jhash): New. * hash.h (STRING_HASH_1, STRING_N_HASH_1): Use jhash. (STRING_HASH_2, STRING_N_HASH_2): Return a dummy value. (STRING_N_COMPARE, return_STRING_N_COMPARE): Prefer memcmp to strncmp.
This commit is contained in:
Paolo Bonzini
Paul Smith
parent
0ca31088dc
commit
4fd56724ad
@ -417,6 +417,10 @@ this program. If not, see <http://www.gnu.org/licenses/>. */
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#define alloca(n) __ALLOCA(n)
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#endif
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/* Define WORDS_BIGENDIAN to 1 if your processor stores words with the most
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significant byte first (like Motorola and SPARC, unlike Intel). */
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/* # undef WORDS_BIGENDIAN */
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/* Output sync sypport */
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#define NO_OUTPUT_SYNC
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@ -450,6 +450,10 @@ char *ttyname (int);
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/* # undef _ALL_SOURCE */
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#endif
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/* Define WORDS_BIGENDIAN to 1 if your processor stores words with the most
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significant byte first (like Motorola and SPARC, unlike Intel). */
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/* # undef WORDS_BIGENDIAN */
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/* Number of bits in a file offset, on hosts where this is settable. */
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/* #undef _FILE_OFFSET_BITS */
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@ -49,6 +49,7 @@ AC_CANONICAL_HOST
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AC_AIX
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AC_ISC_POSIX
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AC_MINIX
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AC_C_BIGENDIAN
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# Enable gettext, in "external" mode.
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AM_GNU_GETTEXT_VERSION([0.19.4])
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148
hash.c
148
hash.c
@ -327,3 +327,151 @@ round_up_2 (unsigned long n)
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return n + 1;
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}
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#define rol32(v, n) \
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((v) << (n) | ((v) >> (32 - (n))))
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/* jhash_mix -- mix 3 32-bit values reversibly. */
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#define jhash_mix(a, b, c) \
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{ \
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a -= c; a ^= rol32(c, 4); c += b; \
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b -= a; b ^= rol32(a, 6); a += c; \
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c -= b; c ^= rol32(b, 8); b += a; \
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a -= c; a ^= rol32(c, 16); c += b; \
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b -= a; b ^= rol32(a, 19); a += c; \
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c -= b; c ^= rol32(b, 4); b += a; \
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}
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/* jhash_final - final mixing of 3 32-bit values (a,b,c) into c */
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#define jhash_final(a, b, c) \
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{ \
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c ^= b; c -= rol32(b, 14); \
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a ^= c; a -= rol32(c, 11); \
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b ^= a; b -= rol32(a, 25); \
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c ^= b; c -= rol32(b, 16); \
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a ^= c; a -= rol32(c, 4); \
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b ^= a; b -= rol32(a, 14); \
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c ^= b; c -= rol32(b, 24); \
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}
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/* An arbitrary initial parameter */
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#define JHASH_INITVAL 0xdeadbeef
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#define sum_get_unaligned_32(r, p) \
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do { \
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unsigned int val; \
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memcpy(&val, (p), 4); \
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r += val; \
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} while(0);
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unsigned jhash(unsigned const char *k, int length)
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{
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unsigned int a, b, c;
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/* Set up the internal state */
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a = b = c = JHASH_INITVAL + length;
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/* All but the last block: affect some 32 bits of (a,b,c) */
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while (length > 12) {
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sum_get_unaligned_32(a, k);
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sum_get_unaligned_32(b, k + 4);
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sum_get_unaligned_32(c, k + 8);
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jhash_mix(a, b, c);
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length -= 12;
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k += 12;
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}
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if (!length)
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return c;
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if (length > 8)
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{
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sum_get_unaligned_32(a, k);
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length -= 4;
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k += 4;
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}
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if (length > 4)
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{
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sum_get_unaligned_32(b, k);
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length -= 4;
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k += 4;
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}
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if (length == 4)
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c += (unsigned)k[3]<<24;
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if (length >= 3)
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c += (unsigned)k[2]<<16;
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if (length >= 2)
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c += (unsigned)k[1]<<8;
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c += k[0];
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jhash_final(a, b, c);
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return c;
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}
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#ifdef WORDS_BIGENDIAN
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/* The ifs are ordered from the first byte in memory to the last. */
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#define sum_up_to_nul(r, p, flag) \
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do { \
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unsigned int val; \
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memcpy(&val, (p), 4); \
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if ((val & 0xFF000000) == 0) \
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flag = 1; \
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else if ((val & 0xFF0000) == 0) \
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r += val & ~0xFFFF, flag = 1; \
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else if ((val & 0xFF00) == 0) \
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r += val & ~0xFF, flag = 1; \
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else \
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r += val, flag = (val & 0xFF) == 0; \
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} while (0)
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#else
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/* First detect the presence of zeroes. If there is none, we can
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sum the 4 bytes directly. Otherwise, the ifs are ordered as in the
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big endian case, from the first byte in memory to the last. */
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#define sum_up_to_nul(r, p, flag) \
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do { \
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unsigned int val; \
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unsigned int zeroes; \
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memcpy(&val, (p), 4); \
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zeroes = ((val - 0x01010101) & ~val); \
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if (!(zeroes & 0x80808080)) \
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r += val; \
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else if ((val & 0xFF) == 0) \
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flag = 1; \
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else if ((val & 0xFF00) == 0) \
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r += val & 0xFF, flag = 1; \
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else if ((val & 0xFF0000) == 0) \
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r += val & 0xFFFF, flag = 1; \
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else \
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r += val, flag = 1; \
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} while (0)
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#endif
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unsigned jhash_string(unsigned const char *k)
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{
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unsigned int a, b, c;
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unsigned int have_nul = 0;
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unsigned const char *start = k;
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/* Set up the internal state */
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a = b = c = JHASH_INITVAL;
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/* All but the last block: affect some 32 bits of (a,b,c) */
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for (;;) {
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sum_up_to_nul(a, k, have_nul);
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if (have_nul)
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break;
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k += 4;
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sum_up_to_nul(b, k, have_nul);
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if (have_nul)
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break;
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k += 4;
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sum_up_to_nul(c, k, have_nul);
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if (have_nul)
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break;
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k += 4;
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jhash_mix(a, b, c);
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}
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jhash_final(a, b, c);
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return c + (k - start);
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}
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40
hash.h
40
hash.h
@ -73,6 +73,9 @@ void hash_map_arg __P((struct hash_table *ht, hash_map_arg_func_t map, void *arg
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void hash_print_stats __P((struct hash_table *ht, FILE *out_FILE));
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void **hash_dump __P((struct hash_table *ht, void **vector_0, qsort_cmp_t compare));
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extern unsigned jhash(unsigned char const *key, int n);
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extern unsigned jhash_string(unsigned char const *key);
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extern void *hash_deleted_item;
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#define HASH_VACANT(item) ((item) == 0 || (void *) (item) == hash_deleted_item)
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@ -83,9 +86,8 @@ extern void *hash_deleted_item;
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be identical. Take advantage of that to short-circuit string compares. */
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#define STRING_HASH_1(KEY, RESULT) do { \
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unsigned char const *_key_ = (unsigned char const *) (KEY) - 1; \
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while (*++_key_) \
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(RESULT) += (*_key_ << (_key_[1] & 0xf)); \
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unsigned char const *_key_ = (unsigned char const *) (KEY); \
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(RESULT) += jhash_string(_key_); \
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} while (0)
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#define return_STRING_HASH_1(KEY) do { \
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unsigned long _result_ = 0; \
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@ -93,10 +95,11 @@ extern void *hash_deleted_item;
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return _result_; \
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} while (0)
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/* No need for a second hash because jhash already provides
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pretty good results. However, do evaluate the arguments
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to avoid warnings. */
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#define STRING_HASH_2(KEY, RESULT) do { \
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unsigned char const *_key_ = (unsigned char const *) (KEY) - 1; \
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while (*++_key_) \
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(RESULT) += (*_key_ << (_key_[1] & 0x7)); \
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(void)(KEY); \
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} while (0)
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#define return_STRING_HASH_2(KEY) do { \
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unsigned long _result_ = 0; \
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@ -113,27 +116,24 @@ extern void *hash_deleted_item;
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#define STRING_N_HASH_1(KEY, N, RESULT) do { \
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unsigned char const *_key_ = (unsigned char const *) (KEY) - 1; \
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int _n_ = (N); \
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if (_n_) \
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while (--_n_ && *++_key_) \
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(RESULT) += (*_key_ << (_key_[1] & 0xf)); \
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(RESULT) += *++_key_; \
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unsigned char const *_key_ = (unsigned char const *) (KEY); \
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(RESULT) += jhash(_key_, N); \
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} while (0)
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#define return_STRING_N_HASH_1(KEY, N) do { \
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unsigned long _result_ = 0; \
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STRING_N_HASH_1 ((KEY), (N), _result_); \
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return _result_; \
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} while (0)
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/* No need for a second hash because jhash already provides
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pretty good results. However, do evaluate the arguments
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to avoid warnings. */
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#define STRING_N_HASH_2(KEY, N, RESULT) do { \
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unsigned char const *_key_ = (unsigned char const *) (KEY) - 1; \
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int _n_ = (N); \
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if (_n_) \
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while (--_n_ && *++_key_) \
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(RESULT) += (*_key_ << (_key_[1] & 0x7)); \
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(RESULT) += *++_key_; \
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(void)(KEY); \
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(void)(N); \
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} while (0)
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#define return_STRING_N_HASH_2(KEY, N) do { \
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unsigned long _result_ = 0; \
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STRING_N_HASH_2 ((KEY), (N), _result_); \
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@ -141,10 +141,10 @@ extern void *hash_deleted_item;
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} while (0)
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#define STRING_N_COMPARE(X, Y, N, RESULT) do { \
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RESULT = (X) == (Y) ? 0 : strncmp ((X), (Y), (N)); \
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RESULT = (X) == (Y) ? 0 : memcmp ((X), (Y), (N)); \
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} while (0)
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#define return_STRING_N_COMPARE(X, Y, N) do { \
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return (X) == (Y) ? 0 : strncmp ((X), (Y), (N)); \
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return (X) == (Y) ? 0 : memcmp ((X), (Y), (N)); \
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} while (0)
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#ifdef HAVE_CASE_INSENSITIVE_FS
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@ -57,7 +57,7 @@ $answer = "cp foo.f foo.e\ncp foo.e foo.d\nrm foo.e\n";
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# TEST #3
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&run_make_with_options($makefile,'foo.c',&get_logfile);
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$answer = "cp foo.f foo.e\ncp bar.f bar.e\ncat foo.e bar.e > foo.c\nrm bar.e foo.e\n";
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$answer = "cp foo.f foo.e\ncp bar.f bar.e\ncat foo.e bar.e > foo.c\nrm foo.e bar.e\n";
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&compare_output($answer, &get_logfile(1));
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# TEST #4
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@ -72,7 +72,7 @@ $answer = "$make_name: 'foo.c' is up to date.\n";
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&touch('foo.f');
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&run_make_with_options($makefile,'foo.c',&get_logfile);
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$answer = "cp foo.f foo.e\ncp bar.f bar.e\ncat foo.e bar.e > foo.c\nrm bar.e foo.e\n";
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$answer = "cp foo.f foo.e\ncp bar.f bar.e\ncat foo.e bar.e > foo.c\nrm foo.e bar.e\n";
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&compare_output($answer, &get_logfile(1));
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# TEST #6 -- added for PR/1669: don't remove files mentioned on the cmd line.
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@ -93,8 +93,7 @@ print MAKEFILE <<'EOF';
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final: intermediate
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intermediate: source
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final intermediate source:
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echo $< > $@
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final intermediate source: ; echo $< > $@
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EOF
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close(MAKEFILE);
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@ -135,7 +134,7 @@ all : 1.c 2.c
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cp 1.b 1.c
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cp 2.a 2.b
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cp 2.b 2.c
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rm 1.b 2.b');
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rm 2.b 1.b');
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unlink(qw(1.a 2.a 1.c 2.c));
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