When building with Clang 10 on Fedora 32, we get:
tests/qht-bench.c:287:29: error: implicit conversion from 'unsigned long' to
'double' changes value from 18446744073709551615 to 18446744073709551616
[-Werror,-Wimplicit-int-float-conversion]
*threshold = rate * UINT64_MAX;
~ ^~~~~~~~~~
/usr/include/stdint.h:130:23: note: expanded from macro 'UINT64_MAX'
# define UINT64_MAX (__UINT64_C(18446744073709551615))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/stdint.h:107:25: note: expanded from macro '__UINT64_C'
# define __UINT64_C(c) c ## UL
^~~~~~~
<scratch space>:14:1: note: expanded from here
18446744073709551615UL
^~~~~~~~~~~~~~~~~~~~~~
Fix by using nextafter() from <math.h>:
double nextafter( double from, double to );
Returns the next representable value of 'from'
in the direction of 'to'.
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
Since v1: nextafterf() -> nextafter()
Cc: Emilio G. Cota <address@hidden>
Cc: Alex Bennée <address@hidden>
Cc: Richard Henderson <address@hidden>
Cc: Alexander Bulekov <address@hidden>
---
tests/qht-bench.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/tests/qht-bench.c b/tests/qht-bench.c
index e3b512f26f..54ce1e8188 100644
--- a/tests/qht-bench.c
+++ b/tests/qht-bench.c
@@ -10,6 +10,7 @@
#include "qemu/qht.h"
#include "qemu/rcu.h"
#include "qemu/xxhash.h"
+#include <math.h>
struct thread_stats {
size_t rd;
@@ -284,7 +285,7 @@ static void do_threshold(double rate, uint64_t *threshold)
if (rate == 1.0) {
*threshold = UINT64_MAX;
} else {
- *threshold = rate * UINT64_MAX;
+ *threshold = rate * nextafter(0x1p64, 0.0);
}
}