From: Vijaya Kumar K <vijaya.ku...@cavium.com>
Optional parameters of __builtin_prefetch() which specifies
rw and locality to 0's. For checking buffer is zero, set rw as read
and temporal locality to 0.
On arm64, __builtin_prefetch(addr) generates 'prfm pldl1keep'
where __builtin_prefetch(addr, 0, 0) generates 'prfm pldl1strm'
instruction which is optimal for this use case
Signed-off-by: Vijaya Kumar K <vijaya.ku...@cavium.com>
Reviewed-by: Richard Henderson <r...@twiddle.net>
---
util/bufferiszero.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/util/bufferiszero.c b/util/bufferiszero.c
index eb974b7..421d945 100644
--- a/util/bufferiszero.c
+++ b/util/bufferiszero.c
@@ -49,7 +49,7 @@ buffer_zero_int(const void *buf, size_t len)
const uint64_t *e = (uint64_t *)(((uintptr_t)buf + len) & -8);
for (; p + 8 <= e; p += 8) {
- __builtin_prefetch(p + 8);
+ __builtin_prefetch(p + 8, 0, 0);
if (t) {
return false;
}
@@ -86,7 +86,7 @@ buffer_zero_sse2(const void *buf, size_t len)
/* Loop over 16-byte aligned blocks of 64. */
while (likely(p <= e)) {
- __builtin_prefetch(p);
+ __builtin_prefetch(p, 0, 0);
t = _mm_cmpeq_epi8(t, zero);
if (unlikely(_mm_movemask_epi8(t) != 0xFFFF)) {
return false;
@@ -127,7 +127,7 @@ buffer_zero_sse4(const void *buf, size_t len)
/* Loop over 16-byte aligned blocks of 64. */
while (likely(p <= e)) {
- __builtin_prefetch(p);
+ __builtin_prefetch(p, 0, 0);
if (unlikely(!_mm_testz_si128(t, t))) {
return false;
}
@@ -162,7 +162,7 @@ buffer_zero_avx2(const void *buf, size_t len)
if (likely(p <= e)) {
/* Loop over 32-byte aligned blocks of 128. */
do {
- __builtin_prefetch(p);
+ __builtin_prefetch(p, 0, 0);
if (unlikely(!_mm256_testz_si256(t, t))) {
return false;
}
@@ -303,7 +303,7 @@ bool buffer_is_zero(const void *buf, size_t len)
}
/* Fetch the beginning of the buffer while we select the accelerator. */
- __builtin_prefetch(buf);
+ __builtin_prefetch(buf, 0, 0);
/* Use an optimized zero check if possible. Note that this also
includes a check for an unrolled loop over 64-bit integers. */
--
1.9.1
