[FYI wayland] tests: add noop to fixed-benchmark

[Pekka Paalanen]

I was just curious of how much the looping takes time without
conversion, so I added this.

My results on Intel(R) Core(TM) i5-2410M CPU @ 2.30GHz:

benchmarked noop:	1.876349827s
benchmarked magic:	2.245844470s
benchmarked div:	12.709085309s
benchmarked mul:	7.504838141s

Mul seems to take 15x the time magic does, cool!

Btw. the simple default cast of int32_t to double is slower than magic
for me, hence the use of union.

Signed-off-by: Pekka Paalanen <ppaalanen at gmail.com>
---
 tests/fixed-benchmark.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/tests/fixed-benchmark.c b/tests/fixed-benchmark.c
index 3f7aae3..0d7abd0 100644
--- a/tests/fixed-benchmark.c
+++ b/tests/fixed-benchmark.c
@@ -30,6 +30,21 @@
 volatile double global_d;
 
 static void
+noop_conversion(void)
+{
+	wl_fixed_t f;
+	union {
+		int64_t i;
+		double d;
+	} u;
+
+	for (f = 0; f < INT32_MAX; f++) {
+		u.i = f;
+		global_d = u.d;
+	}
+}
+
+static void
 magic_conversion(void)
 {
 	wl_fixed_t f;
@@ -80,6 +95,7 @@ benchmark(const char *s, void (*f)(void))
 
 int main(int argc, char *argv[])
 {
+	benchmark("noop", noop_conversion);
 	benchmark("magic", magic_conversion);
 	benchmark("div", div_conversion);
 	benchmark("mul", mul_conversion);
-- 
1.7.3.4