From 4cbd39b289b012782df2fdda9adc7eacdcfc6ad7 Mon Sep 17 00:00:00 2001 From: Christian Biesinger Date: Mon, 2 Dec 2019 18:58:35 -0600 Subject: 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 * bcache.c (hash): Remove. (hash_continue): Remove. * bcache.h (hash): Remove. (hash_continue): Remove. (struct bcache) : 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 --- gdb/utils.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'gdb/utils.h') 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 } -- cgit v1.1