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| author | Christian Biesinger <cbiesinger@google.com> | 2019-12-02 18:58:35 -0600 |
|---|---|---|
| committer | Christian Biesinger <cbiesinger@google.com> | 2019-12-03 15:27:15 -0600 |
| commit | 4cbd39b289b012782df2fdda9adc7eacdcfc6ad7 (patch) | |
| tree | f52aba927c48c83dca2923c7c3c0c55657ca29c1 /gdb/utils.h | |
| parent | 82f910ea9cce04b0faabfcd022d9d8949567541e (diff) | |
| download | gdb-4cbd39b289b012782df2fdda9adc7eacdcfc6ad7.zip gdb-4cbd39b289b012782df2fdda9adc7eacdcfc6ad7.tar.gz gdb-4cbd39b289b012782df2fdda9adc7eacdcfc6ad7.tar.bz2 | |
Replace hash function from bcache with fast_hash
This function is not just slower than xxhash, it is slower than
even libiberty's iterative_hash, so there does not seem to be
a reason for it to exist.
------------------------------------------------------------
Benchmark Time CPU Iterations
------------------------------------------------------------
BM_xxh3 11 ns 11 ns 66127192
BM_xxh32 19 ns 19 ns 36792609
BM_xxh64 16 ns 16 ns 42941328
BM_city32 26 ns 26 ns 27028370
BM_city64 17 ns 17 ns 40472793
BM_iterative_hash 77 ns 77 ns 9088854
BM_bcache_hash 125 ns 125 ns 5599232
gdb/ChangeLog:
2019-12-03 Christian Biesinger <cbiesinger@google.com>
* bcache.c (hash): Remove.
(hash_continue): Remove.
* bcache.h (hash): Remove.
(hash_continue): Remove.
(struct bcache) <ctor>: Update.
* psymtab.c (psymbol_hash): Update.
* stabsread.c (hashname): Update.
* utils.h (fast_hash): Add an argument for a start value,
defaulting to zero.
Change-Id: I107f013eda5fdd3293326b5a206be43155dae0f8
Diffstat (limited to 'gdb/utils.h')
| -rw-r--r-- | gdb/utils.h | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/gdb/utils.h b/gdb/utils.h index 79c8a6f..c8337f2 100644 --- a/gdb/utils.h +++ b/gdb/utils.h @@ -571,17 +571,18 @@ extern void copy_bitwise (gdb_byte *dest, ULONGEST dest_offset, const gdb_byte *source, ULONGEST source_offset, ULONGEST nbits, int bits_big_endian); -/* A fast hashing function. This can be used to hash strings in a fast way +/* A fast hashing function. This can be used to hash data in a fast way when the length is known. If no fast hashing library is available, falls - back to iterative_hash from libiberty. */ + back to iterative_hash from libiberty. START_VALUE can be set to + continue hashing from a previous value. */ static inline unsigned int -fast_hash (const char* str, size_t len) +fast_hash (const void *ptr, size_t len, unsigned int start_value = 0) { #ifdef HAVE_LIBXXHASH - return XXH64 (str, len, 0); + return XXH64 (ptr, len, start_value); #else - return iterative_hash (str, len, 0); + return iterative_hash (ptr, len, start_value); #endif } |