public inbox for glibc-cvs@sourceware.org
help / color / mirror / Atom feed
* [glibc] benchtests: Add difficult strstr needle for bruteforce algorithms
@ 2024-04-24 17:26 Wilco Dijkstra
0 siblings, 0 replies; only message in thread
From: Wilco Dijkstra @ 2024-04-24 17:26 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f262fce61671c38d436d2d0cd68dab5642ac9ef0
commit f262fce61671c38d436d2d0cd68dab5642ac9ef0
Author: Wilco Dijkstra <wilco.dijkstra@arm.com>
Date: Wed Apr 24 18:24:45 2024 +0100
benchtests: Add difficult strstr needle for bruteforce algorithms
Add another difficult needle to strstr that clearly shows the quadratic
complexity of bruteforce algorithms.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diff:
---
benchtests/bench-strstr.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/benchtests/bench-strstr.c b/benchtests/bench-strstr.c
index 9288ad16e9..4b07d39a50 100644
--- a/benchtests/bench-strstr.c
+++ b/benchtests/bench-strstr.c
@@ -352,6 +352,33 @@ test_hard_needle (json_ctx_t *json_ctx, size_t ne_len, size_t hs_len)
json_array_end (json_ctx);
json_element_object_end (json_ctx);
}
+
+ /* Hard needle for bruteforce algorithms that match first few chars. */
+ {
+ memset (hs, 'a', hs_len);
+ for (int i = ne_len-1; i < hs_len; i += ne_len)
+ hs[i] = 'b';
+ hs[hs_len] = 0;
+
+ memset (ne, 'a', ne_len);
+ ne[ne_len] = 0;
+
+ json_element_object_begin (json_ctx);
+ json_attr_uint (json_ctx, "len_haystack", hs_len);
+ json_attr_uint (json_ctx, "len_needle", ne_len);
+ json_attr_uint (json_ctx, "align_haystack", 0);
+ json_attr_uint (json_ctx, "align_needle", 0);
+ json_attr_uint (json_ctx, "fail", 1);
+ json_attr_string (json_ctx, "desc", "Difficult bruteforce needle");
+
+ json_array_begin (json_ctx, "timings");
+
+ FOR_EACH_IMPL (impl, 0)
+ do_one_test (json_ctx, impl, hs, ne, NULL);
+
+ json_array_end (json_ctx);
+ json_element_object_end (json_ctx);
+ }
}
static int
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2024-04-24 17:26 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-04-24 17:26 [glibc] benchtests: Add difficult strstr needle for bruteforce algorithms Wilco Dijkstra
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).