tests/bench: Add bufferiszero-bench

Benchmark each acceleration function vs an aligned buffer of zeros.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tests/bench/bufferiszero-bench.c

@@ -0,0 +1,47 @@
+/*
+ * QEMU buffer_is_zero speed benchmark
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.  See the COPYING file in the
+ * top-level directory.
+ */
+#include "qemu/osdep.h"
+#include "qemu/cutils.h"
+#include "qemu/units.h"
+
+static void test(const void *opaque)
+{
+    size_t max = 64 * KiB;
+    void *buf = g_malloc0(max);
+    int accel_index = 0;
+
+    do {
+        if (accel_index != 0) {
+            g_test_message("%s", "");  /* gnu_printf Werror for simple "" */
+        }
+        for (size_t len = 1 * KiB; len <= max; len *= 4) {
+            double total = 0.0;
+
+            g_test_timer_start();
+            do {
+                buffer_is_zero_ge256(buf, len);
+                total += len;
+            } while (g_test_timer_elapsed() < 0.5);
+
+            total /= MiB;
+            g_test_message("buffer_is_zero #%d: %2zuKB %8.0f MB/sec",
+                           accel_index, len / (size_t)KiB,
+                           total / g_test_timer_last());
+        }
+        accel_index++;
+    } while (test_buffer_is_zero_next_accel());
+
+    g_free(buf);
+}
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+    g_test_add_data_func("/cutils/bufferiszero/speed", NULL, test);
+    return g_test_run();
+}

tests/bench/meson.build

@@ -21,6 +21,7 @@ benchs = {}
 
 if have_block
   benchs += {
+     'bufferiszero-bench': [],
      'benchmark-crypto-hash': [crypto],
      'benchmark-crypto-hmac': [crypto],
      'benchmark-crypto-cipher': [crypto],