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[PATCH] Improve bench-strstr


Improve bench-strstr by using an extract from the manual as the input
to make the test more realistic.  Use the same input for both found and
fail cases rather than using a memset of '0' for most of the string,
which measures performance of strchr rather than strstr.  Add result
checking to catch potential errors.  Remove the repeated tests at slightly
different alignments and add more large needle and haystack testcases.

ChangeLog:
2018-10-29  Wilco Dijkstra  <wdijkstr@arm.com>

	* benchtests/bench-strstr.c (input): Added realistic input text.
	(do_one_test): Increase iterations.  Add result checking.
	(do_test): Use new input text.  Remove accidental early matches.
	(test_main): Improve range of tests, reduce unaligned cases.
--


diff --git a/benchtests/bench-strstr.c b/benchtests/bench-strstr.c
index a31294e3c96d80a4fd61bb5b423a825fe54d3227..00cb779ab39ad01614896458bdcc7ff0d012c618 100644
--- a/benchtests/bench-strstr.c
+++ b/benchtests/bench-strstr.c
@@ -16,6 +16,7 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#define MIN_PAGE_SIZE 131072
 #define TEST_MAIN
 #define TEST_NAME "strstr"
 #include "bench-string.h"
@@ -26,6 +27,30 @@
 #define __strnlen strnlen
 #include "../string/strstr.c"
 
+static const char input[] =
+"This manual is written with the assumption that you are at least "
+"somewhat familiar with the C programming language and basic programming "
+"concepts.  Specifically, familiarity with ISO standard C (*note ISO "
+"C::), rather than “traditional” pre-ISO C dialects, is assumed.\n"
+
+"   The GNU C Library includes several “header files”, each of which "
+"provides definitions and declarations for a group of related facilities; "
+"this information is used by the C compiler when processing your program. "
+"For example, the header file ‘stdio.h’ declares facilities for "
+"performing input and output, and the header file ‘string.h’ declares "
+"string processing utilities.  The organization of this manual generally "
+"follows the same division as the header files.\n"
+
+"   If you are reading this manual for the first time, you should read "
+"all of the introductory material and skim the remaining chapters.  There "
+"are a _lot_ of functions in the GNU C Library and it’s not realistic to "
+"expect that you will be able to remember exactly _how_ to use each and "
+"every one of them.  It’s more important to become generally familiar "
+"with the kinds of facilities that the library provides, so that when you "
+"are writing your programs you can recognize _when_ to make use of "
+"library functions, and _where_ in this manual you can find more specific "
+"information about them.\n";
+
 
 static char *
 stupid_strstr (const char *s1, const char *s2)
@@ -60,19 +85,25 @@ IMPL (strstr, 1)
 static void
 do_one_test (impl_t *impl, const char *s1, const char *s2, char *exp_result)
 {
-  size_t i, iters = INNER_LOOP_ITERS;
+  size_t i, iters = INNER_LOOP_ITERS * 2;
   timing_t start, stop, cur;
+  char *res;
 
   TIMING_NOW (start);
   for (i = 0; i < iters; ++i)
-    {
-      CALL (impl, s1, s2);
-    }
+    res = CALL (impl, s1, s2);
   TIMING_NOW (stop);
 
   TIMING_DIFF (cur, start, stop);
 
   TIMING_PRINT_MEAN ((double) cur, (double) iters);
+
+  if (res != exp_result)
+    {
+      error (0, 0, "Wrong result in function %s %s %s", impl->name,
+	     res, exp_result);
+      ret = 1;
+    }
 }
 
 
@@ -83,36 +114,42 @@ do_test (size_t align1, size_t align2, size_t len1, size_t len2,
   char *s1 = (char *) (buf1 + align1);
   char *s2 = (char *) (buf2 + align2);
 
-  static const char d[] = "1234567890abcdef";
-#define dl (sizeof (d) - 1)
-  char *ss2 = s2;
-  for (size_t l = len2; l > 0; l = l > dl ? l - dl : 0)
-    {
-      size_t t = l > dl ? dl : l;
-      ss2 = mempcpy (ss2, d, t);
-    }
-  s2[len2] = '\0';
+  size_t size = sizeof (input) - 1;
+  size_t pos = (len1 + len2) % size;
 
-  if (fail)
+  char *ss2 = s2;
+  for (size_t l = len2; l > 0; l = l > size ? l - size : 0)
     {
-      char *ss1 = s1;
-      for (size_t l = len1; l > 0; l = l > dl ? l - dl : 0)
+      size_t t = l > size ? size : l;
+      if (pos + t <= size)
+	ss2 = mempcpy (ss2, input + pos, t);
+      else
 	{
-	  size_t t = l > dl ? dl : l;
-	  memcpy (ss1, d, t);
-	  ++ss1[len2 > 7 ? 7 : len2 - 1];
-	  ss1 += t;
+	  ss2 = mempcpy (ss2, input + pos, size - pos);
+	  ss2 = mempcpy (ss2, input, t - (size - pos));
 	}
     }
-  else
+  s2[len2] = '\0';
+
+  char *ss1 = s1;
+  for (size_t l = len1; l > 0; l = l > size ? l - size : 0)
     {
-      memset (s1, '0', len1);
-      memcpy (s1 + len1 - len2, s2, len2);
+      size_t t = l > size ? size : l;
+      memcpy (ss1, input, t);
+      ss1 += t;
     }
+
+  if (!fail)
+    memcpy (s1 + len1 - len2, s2, len2);
   s1[len1] = '\0';
 
-  printf ("Length %4zd/%zd, alignment %2zd/%2zd, %s:",
-	  len1, len2, align1, align2, fail ? "fail" : "found");
+  /* Remove any accidental matches except for the last if !fail.  */
+  for (ss1 = stupid_strstr (s1, s2); ss1; ss1 = stupid_strstr (ss1 + 1, s2))
+    if (fail || ss1 != s1 + len1 - len2)
+      ++ss1[len2 / 2];
+
+  printf ("Length %4zd/%3zd, alignment %2zd/%2zd, %s:",
+	  len1, len2, align1, align2, fail ? "fail " : "found");
 
   FOR_EACH_IMPL (impl, 0)
     do_one_test (impl, s1, s2, fail ? NULL : s1 + len1 - len2);
@@ -130,48 +167,19 @@ test_main (void)
     printf ("\t%s", impl->name);
   putchar ('\n');
 
-  for (size_t klen = 2; klen < 32; ++klen)
-    for (size_t hlen = 2 * klen; hlen < 16 * klen; hlen += klen)
+  for (size_t hlen = 64; hlen <= 256; hlen += 32)
+    for (size_t klen = 1; klen <= 16; klen++)
       {
-	do_test (0, 0, hlen, klen, 0);
-	do_test (0, 0, hlen, klen, 1);
-	do_test (0, 3, hlen, klen, 0);
-	do_test (0, 3, hlen, klen, 1);
-	do_test (0, 9, hlen, klen, 0);
+	do_test (1, 3, hlen, klen, 0);
 	do_test (0, 9, hlen, klen, 1);
-	do_test (0, 15, hlen, klen, 0);
-	do_test (0, 15, hlen, klen, 1);
-
-	do_test (3, 0, hlen, klen, 0);
-	do_test (3, 0, hlen, klen, 1);
-	do_test (3, 3, hlen, klen, 0);
-	do_test (3, 3, hlen, klen, 1);
-	do_test (3, 9, hlen, klen, 0);
-	do_test (3, 9, hlen, klen, 1);
-	do_test (3, 15, hlen, klen, 0);
-	do_test (3, 15, hlen, klen, 1);
-
-	do_test (9, 0, hlen, klen, 0);
-	do_test (9, 0, hlen, klen, 1);
-	do_test (9, 3, hlen, klen, 0);
-	do_test (9, 3, hlen, klen, 1);
-	do_test (9, 9, hlen, klen, 0);
-	do_test (9, 9, hlen, klen, 1);
-	do_test (9, 15, hlen, klen, 0);
-	do_test (9, 15, hlen, klen, 1);
-
-	do_test (15, 0, hlen, klen, 0);
-	do_test (15, 0, hlen, klen, 1);
-	do_test (15, 3, hlen, klen, 0);
-	do_test (15, 3, hlen, klen, 1);
-	do_test (15, 9, hlen, klen, 0);
-	do_test (15, 9, hlen, klen, 1);
-	do_test (15, 15, hlen, klen, 0);
-	do_test (15, 15, hlen, klen, 1);
       }
 
-  do_test (0, 0, page_size - 1, 16, 0);
-  do_test (0, 0, page_size - 1, 16, 1);
+  for (size_t hlen = 256; hlen <= 65536; hlen *= 2)
+    for (size_t klen = 16; klen <= 256; klen *= 2)
+      {
+	do_test (1, 11, hlen, klen, 0);
+	do_test (14, 5, hlen, klen, 1);
+      }
 
   return ret;
 }


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