benchtests: Add more coverage for strcmp and strncmp benchmarks

Add more small and medium sized tests for strcmp and strncmp.

As well for strcmp add option for more direct control of
alignment. Previously alignment was being pushed to the end of the
page. While this is the most difficult case to implement, it is far
from the common case and so shouldn't be the only benchmark.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>

1 files changed, 102 insertions, 40 deletions

diff --git a/benchtests/bench-strcmp.c b/benchtests/bench-strcmp.c
index 387e76fcfb..3a60edfb15 100644
--- a/benchtests/bench-strcmp.c
+++ b/benchtests/bench-strcmp.c
@@ -99,8 +99,8 @@ do_one_test (json_ctx_t *json_ctx, impl_t *impl,
 }
 
 static void
-do_test (json_ctx_t *json_ctx, size_t align1, size_t align2, size_t len, int
-	 max_char, int exp_result)
+do_test (json_ctx_t *json_ctx, size_t align1, size_t align2, size_t len,
+         int max_char, int exp_result, int at_end)
 {
   size_t i;
 
@@ -109,19 +109,28 @@ do_test (json_ctx_t *json_ctx, size_t align1, size_t align2, size_t len, int
   if (len == 0)
     return;
 
-  align1 &= 63;
+  align1 &= ~(CHARBYTES - 1);
+  align2 &= ~(CHARBYTES - 1);
+
+  align1 &= (getpagesize () - 1);
   if (align1 + (len + 1) * CHARBYTES >= page_size)
     return;
 
-  align2 &= 63;
+  align2 &= (getpagesize () - 1);
   if (align2 + (len + 1) * CHARBYTES >= page_size)
     return;
 
   /* Put them close to the end of page.  */
-  i = align1 + CHARBYTES * (len + 2);
-  s1 = (CHAR *) (buf1 + ((page_size - i) / 16 * 16) + align1);
-  i = align2 + CHARBYTES * (len + 2);
-  s2 = (CHAR *) (buf2 + ((page_size - i) / 16 * 16)  + align2);
+  if (at_end)
+    {
+      i = align1 + CHARBYTES * (len + 2);
+      align1 = ((page_size - i) / 16 * 16) + align1;
+      i = align2 + CHARBYTES * (len + 2);
+      align2 = ((page_size - i) / 16 * 16) + align2;
+    }
+
+  s1 = (CHAR *)(buf1 + align1);
+  s2 = (CHAR *)(buf2 + align2);
 
   for (i = 0; i < len; i++)
     s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % max_char;
@@ -132,9 +141,9 @@ do_test (json_ctx_t *json_ctx, size_t align1, size_t align2, size_t len, int
   s2[len - 1] -= exp_result;
 
   json_element_object_begin (json_ctx);
-  json_attr_uint (json_ctx, "length", (double) len);
-  json_attr_uint (json_ctx, "align1", (double) align1);
-  json_attr_uint (json_ctx, "align2", (double) align2);
+  json_attr_uint (json_ctx, "length", (double)len);
+  json_attr_uint (json_ctx, "align1", (double)align1);
+  json_attr_uint (json_ctx, "align2", (double)align2);
   json_array_begin (json_ctx, "timings");
 
   FOR_EACH_IMPL (impl, 0)
@@ -202,7 +211,8 @@ int
 test_main (void)
 {
   json_ctx_t json_ctx;
-  size_t i;
+  size_t i, j, k;
+  size_t pg_sz = getpagesize ();
 
   test_init ();
 
@@ -221,36 +231,88 @@ test_main (void)
   json_array_end (&json_ctx);
 
   json_array_begin (&json_ctx, "results");
-
-  for (i = 1; i < 32; ++i)
-    {
-      do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 0);
-      do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 1);
-      do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, -1);
-    }
-
-  for (i = 1; i < 10 + CHARBYTESLOG; ++i)
+  for (k = 0; k < 2; ++k)
     {
-      do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 0);
-      do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 0);
-      do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 1);
-      do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 1);
-      do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, -1);
-      do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, -1);
-      do_test (&json_ctx, 0, CHARBYTES * i, 2 << i, MIDCHAR, 1);
-      do_test (&json_ctx, CHARBYTES * i, CHARBYTES * (i + 1), 2 << i, LARGECHAR, 1);
+      for (i = 1; i < 32; ++i)
+        {
+          do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 0, k);
+          do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, 1, k);
+          do_test (&json_ctx, CHARBYTES * i, CHARBYTES * i, i, MIDCHAR, -1, k);
+        }
+
+      for (i = 1; i <= 8192;)
+        {
+          /* No page crosses.  */
+          do_test (&json_ctx, 0, 0, i, MIDCHAR, 0, k);
+          do_test (&json_ctx, i * CHARBYTES, 0, i, MIDCHAR, 0, k);
+          do_test (&json_ctx, 0, i * CHARBYTES, i, MIDCHAR, 0, k);
+
+          /* False page crosses.  */
+          do_test (&json_ctx, pg_sz / 2, pg_sz / 2 - CHARBYTES, i, MIDCHAR, 0,
+                   k);
+          do_test (&json_ctx, pg_sz / 2 - CHARBYTES, pg_sz / 2, i, MIDCHAR, 0,
+                   k);
+
+          do_test (&json_ctx, pg_sz - (i * CHARBYTES), 0, i, MIDCHAR, 0, k);
+          do_test (&json_ctx, 0, pg_sz - (i * CHARBYTES), i, MIDCHAR, 0, k);
+
+          /* Real page cross.  */
+          for (j = 16; j < 128; j += 16)
+            {
+              do_test (&json_ctx, pg_sz - j, 0, i, MIDCHAR, 0, k);
+              do_test (&json_ctx, 0, pg_sz - j, i, MIDCHAR, 0, k);
+
+              do_test (&json_ctx, pg_sz - j, pg_sz - j / 2, i, MIDCHAR, 0, k);
+              do_test (&json_ctx, pg_sz - j / 2, pg_sz - j, i, MIDCHAR, 0, k);
+            }
+
+          if (i < 32)
+            {
+              ++i;
+            }
+          else if (i < 160)
+            {
+              i += 8;
+            }
+          else if (i < 512)
+            {
+              i += 32;
+            }
+          else
+            {
+              i *= 2;
+            }
+        }
+
+      for (i = 1; i < 10 + CHARBYTESLOG; ++i)
+        {
+          do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 0, k);
+          do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 0, k);
+          do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, 1, k);
+          do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, 1, k);
+          do_test (&json_ctx, 0, 0, 2 << i, MIDCHAR, -1, k);
+          do_test (&json_ctx, 0, 0, 2 << i, LARGECHAR, -1, k);
+          do_test (&json_ctx, 0, CHARBYTES * i, 2 << i, MIDCHAR, 1, k);
+          do_test (&json_ctx, CHARBYTES * i, CHARBYTES * (i + 1), 2 << i,
+                   LARGECHAR, 1, k);
+        }
+
+      for (i = 1; i < 8; ++i)
+        {
+          do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i,
+                   MIDCHAR, 0, k);
+          do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i,
+                   LARGECHAR, 0, k);
+          do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i,
+                   MIDCHAR, 1, k);
+          do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i,
+                   LARGECHAR, 1, k);
+          do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i,
+                   MIDCHAR, -1, k);
+          do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i,
+                   LARGECHAR, -1, k);
+        }
     }
-
-  for (i = 1; i < 8; ++i)
-    {
-      do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, 0);
-      do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, 0);
-      do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, 1);
-      do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, 1);
-      do_test (&json_ctx, CHARBYTES * i, 2 * CHARBYTES * i, 8 << i, MIDCHAR, -1);
-      do_test (&json_ctx, 2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, -1);
-    }
-
   do_test_page_boundary (&json_ctx);
 
   json_array_end (&json_ctx);