diff options
| author |   Damjan Marion <damarion@cisco.com> | 2021-10-27 18:19:43 +0200 |
|---|---|---|
| committer |   Florin Coras <florin.coras@gmail.com> | 2021-11-02 04:44:06 +0000 |
| commit | 31ee6f5d3069c23b4a11005b95ee3744b9720a17 (patch) | |
| tree | 4e0b0a9504b8cb527ba739d9026c3f8fde8264ae /src/vppinfra/clib.h | |
| parent | 21aa673412b2abc1e113dae08e33eb8992308862 (diff) | |
vppinfra: add CLIB_ASSUME() macro
This macro privides a way to tell compiler that it is safe to assume
that specified expression is true so it can optimize code accordingly.
i.e.
CLIB_ASSUME (n < 3);
while (n)
{
/* ... */
}
Will tell compiler that n is never going to be >= 3 so instead of
creating loop it will just unroll loop 2 times.
Type: improvement
Change-Id: I718a9b95ff7980d7ac68eb9a88357a4ab6eee74a
Signed-off-by: Damjan Marion <damarion@cisco.com>
Diffstat (limited to 'src/vppinfra/clib.h')
| -rw-r--r-- | src/vppinfra/clib.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/vppinfra/clib.h b/src/vppinfra/clib.h index 81b59e21a0b..52e721768bc 100644 --- a/src/vppinfra/clib.h +++ b/src/vppinfra/clib.h @@ -124,6 +124,13 @@ #define PREDICT_FALSE(x) __builtin_expect((x),0) #define PREDICT_TRUE(x) __builtin_expect((x),1) #define COMPILE_TIME_CONST(x) __builtin_constant_p (x) +#define CLIB_ASSUME(x) \ + do \ + { \ + if (!(x)) \ + __builtin_unreachable (); \ + } \ + while (0) /* * Compiler barrier |