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cutils: Move buffer_is_zero and subroutines to a new file 

Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <1472496380-19706-2-git-send-email-rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Richard Henderson 2016-08-29 11:46:12 -07:00 committed by Paolo Bonzini
parent 2286459d3a
commit 88ca8e80de
3 changed files with 273 additions and 244 deletions
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1
util/Makefile.objs
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@ -1,4 +1,5 @@
util-obj-y = osdep.o cutils.o unicode.o qemu-timer-common.o
util-obj-y += bufferiszero.o
util-obj-$(CONFIG_POSIX) += compatfd.o
util-obj-$(CONFIG_POSIX) += event_notifier-posix.o
util-obj-$(CONFIG_POSIX) += mmap-alloc.o

272
util/bufferiszero.c Normal file
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@ -0,0 +1,272 @@
/*
* Simple C functions to supplement the C library
*
* Copyright (c) 2006 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qemu/cutils.h"
/* vector definitions */
#ifdef __ALTIVEC__
#include <altivec.h>
/* The altivec.h header says we're allowed to undef these for
* C++ compatibility. Here we don't care about C++, but we
* undef them anyway to avoid namespace pollution.
*/
#undef vector
#undef pixel
#undef bool
#define VECTYPE __vector unsigned char
#define SPLAT(p) vec_splat(vec_ld(0, p), 0)
#define ALL_EQ(v1, v2) vec_all_eq(v1, v2)
#define VEC_OR(v1, v2) ((v1) | (v2))
/* altivec.h may redefine the bool macro as vector type.
* Reset it to POSIX semantics. */
#define bool _Bool
#elif defined __SSE2__
#include <emmintrin.h>
#define VECTYPE __m128i
#define SPLAT(p) _mm_set1_epi8(*(p))
#define ALL_EQ(v1, v2) (_mm_movemask_epi8(_mm_cmpeq_epi8(v1, v2)) == 0xFFFF)
#define VEC_OR(v1, v2) (_mm_or_si128(v1, v2))
#elif defined(__aarch64__)
#include "arm_neon.h"
#define VECTYPE uint64x2_t
#define ALL_EQ(v1, v2) \
((vgetq_lane_u64(v1, 0) == vgetq_lane_u64(v2, 0)) && \
(vgetq_lane_u64(v1, 1) == vgetq_lane_u64(v2, 1)))
#define VEC_OR(v1, v2) ((v1) | (v2))
#else
#define VECTYPE unsigned long
#define SPLAT(p) (*(p) * (~0UL / 255))
#define ALL_EQ(v1, v2) ((v1) == (v2))
#define VEC_OR(v1, v2) ((v1) | (v2))
#endif
#define BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR 8
static bool
can_use_buffer_find_nonzero_offset_inner(const void *buf, size_t len)
{
return (len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
* sizeof(VECTYPE)) == 0
&& ((uintptr_t) buf) % sizeof(VECTYPE) == 0);
}
/*
* Searches for an area with non-zero content in a buffer
*
* Attention! The len must be a multiple of
* BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR * sizeof(VECTYPE)
* and addr must be a multiple of sizeof(VECTYPE) due to
* restriction of optimizations in this function.
*
* can_use_buffer_find_nonzero_offset_inner() can be used to
* check these requirements.
*
* The return value is the offset of the non-zero area rounded
* down to a multiple of sizeof(VECTYPE) for the first
* BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR chunks and down to
* BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR * sizeof(VECTYPE)
* afterwards.
*
* If the buffer is all zero the return value is equal to len.
*/
static size_t buffer_find_nonzero_offset_inner(const void *buf, size_t len)
{
const VECTYPE *p = buf;
const VECTYPE zero = (VECTYPE){0};
size_t i;
assert(can_use_buffer_find_nonzero_offset_inner(buf, len));
if (!len) {
return 0;
}
for (i = 0; i < BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR; i++) {
if (!ALL_EQ(p[i], zero)) {
return i * sizeof(VECTYPE);
}
}
for (i = BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR;
i < len / sizeof(VECTYPE);
i += BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR) {
VECTYPE tmp0 = VEC_OR(p[i + 0], p[i + 1]);
VECTYPE tmp1 = VEC_OR(p[i + 2], p[i + 3]);
VECTYPE tmp2 = VEC_OR(p[i + 4], p[i + 5]);
VECTYPE tmp3 = VEC_OR(p[i + 6], p[i + 7]);
VECTYPE tmp01 = VEC_OR(tmp0, tmp1);
VECTYPE tmp23 = VEC_OR(tmp2, tmp3);
if (!ALL_EQ(VEC_OR(tmp01, tmp23), zero)) {
break;
}
}
return i * sizeof(VECTYPE);
}
#if defined CONFIG_AVX2_OPT
#pragma GCC push_options
#pragma GCC target("avx2")
#include <cpuid.h>
#include <immintrin.h>
#define AVX2_VECTYPE __m256i
#define AVX2_SPLAT(p) _mm256_set1_epi8(*(p))
#define AVX2_ALL_EQ(v1, v2) \
(_mm256_movemask_epi8(_mm256_cmpeq_epi8(v1, v2)) == 0xFFFFFFFF)
#define AVX2_VEC_OR(v1, v2) (_mm256_or_si256(v1, v2))
static bool
can_use_buffer_find_nonzero_offset_avx2(const void *buf, size_t len)
{
return (len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
* sizeof(AVX2_VECTYPE)) == 0
&& ((uintptr_t) buf) % sizeof(AVX2_VECTYPE) == 0);
}
static size_t buffer_find_nonzero_offset_avx2(const void *buf, size_t len)
{
const AVX2_VECTYPE *p = buf;
const AVX2_VECTYPE zero = (AVX2_VECTYPE){0};
size_t i;
assert(can_use_buffer_find_nonzero_offset_avx2(buf, len));
if (!len) {
return 0;
}
for (i = 0; i < BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR; i++) {
if (!AVX2_ALL_EQ(p[i], zero)) {
return i * sizeof(AVX2_VECTYPE);
}
}
for (i = BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR;
i < len / sizeof(AVX2_VECTYPE);
i += BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR) {
AVX2_VECTYPE tmp0 = AVX2_VEC_OR(p[i + 0], p[i + 1]);
AVX2_VECTYPE tmp1 = AVX2_VEC_OR(p[i + 2], p[i + 3]);
AVX2_VECTYPE tmp2 = AVX2_VEC_OR(p[i + 4], p[i + 5]);
AVX2_VECTYPE tmp3 = AVX2_VEC_OR(p[i + 6], p[i + 7]);
AVX2_VECTYPE tmp01 = AVX2_VEC_OR(tmp0, tmp1);
AVX2_VECTYPE tmp23 = AVX2_VEC_OR(tmp2, tmp3);
if (!AVX2_ALL_EQ(AVX2_VEC_OR(tmp01, tmp23), zero)) {
break;
}
}
return i * sizeof(AVX2_VECTYPE);
}
static bool avx2_support(void)
{
int a, b, c, d;
if (__get_cpuid_max(0, NULL) < 7) {
return false;
}
__cpuid_count(7, 0, a, b, c, d);
return b & bit_AVX2;
}
bool can_use_buffer_find_nonzero_offset(const void *buf, size_t len) \
__attribute__ ((ifunc("can_use_buffer_find_nonzero_offset_ifunc")));
size_t buffer_find_nonzero_offset(const void *buf, size_t len) \
__attribute__ ((ifunc("buffer_find_nonzero_offset_ifunc")));
static void *buffer_find_nonzero_offset_ifunc(void)
{
typeof(buffer_find_nonzero_offset) *func = (avx2_support()) ?
buffer_find_nonzero_offset_avx2 : buffer_find_nonzero_offset_inner;
return func;
}
static void *can_use_buffer_find_nonzero_offset_ifunc(void)
{
typeof(can_use_buffer_find_nonzero_offset) *func = (avx2_support()) ?
can_use_buffer_find_nonzero_offset_avx2 :
can_use_buffer_find_nonzero_offset_inner;
return func;
}
#pragma GCC pop_options
#else
bool can_use_buffer_find_nonzero_offset(const void *buf, size_t len)
{
return can_use_buffer_find_nonzero_offset_inner(buf, len);
}
size_t buffer_find_nonzero_offset(const void *buf, size_t len)
{
return buffer_find_nonzero_offset_inner(buf, len);
}
#endif
/*
* Checks if a buffer is all zeroes
*
* Attention! The len must be a multiple of 4 * sizeof(long) due to
* restriction of optimizations in this function.
*/
bool buffer_is_zero(const void *buf, size_t len)
{
/*
* Use long as the biggest available internal data type that fits into the
* CPU register and unroll the loop to smooth out the effect of memory
* latency.
*/
size_t i;
long d0, d1, d2, d3;
const long * const data = buf;
/* use vector optimized zero check if possible */
if (can_use_buffer_find_nonzero_offset(buf, len)) {
return buffer_find_nonzero_offset(buf, len) == len;
}
assert(len % (4 * sizeof(long)) == 0);
len /= sizeof(long);
for (i = 0; i < len; i += 4) {
d0 = data[i + 0];
d1 = data[i + 1];
d2 = data[i + 2];
d3 = data[i + 3];
if (d0 || d1 || d2 || d3) {
return false;
}
}
return true;
}

244
util/cutils.c
View File

@ -161,250 +161,6 @@ int qemu_fdatasync(int fd)
#endif
}
/* vector definitions */
#ifdef __ALTIVEC__
#include <altivec.h>
/* The altivec.h header says we're allowed to undef these for
* C++ compatibility. Here we don't care about C++, but we
* undef them anyway to avoid namespace pollution.
*/
#undef vector
#undef pixel
#undef bool
#define VECTYPE __vector unsigned char
#define SPLAT(p) vec_splat(vec_ld(0, p), 0)
#define ALL_EQ(v1, v2) vec_all_eq(v1, v2)
#define VEC_OR(v1, v2) ((v1) | (v2))
/* altivec.h may redefine the bool macro as vector type.
* Reset it to POSIX semantics. */
#define bool _Bool
#elif defined __SSE2__
#include <emmintrin.h>
#define VECTYPE __m128i
#define SPLAT(p) _mm_set1_epi8(*(p))
#define ALL_EQ(v1, v2) (_mm_movemask_epi8(_mm_cmpeq_epi8(v1, v2)) == 0xFFFF)
#define VEC_OR(v1, v2) (_mm_or_si128(v1, v2))
#elif defined(__aarch64__)
#include "arm_neon.h"
#define VECTYPE uint64x2_t
#define ALL_EQ(v1, v2) \
((vgetq_lane_u64(v1, 0) == vgetq_lane_u64(v2, 0)) && \
(vgetq_lane_u64(v1, 1) == vgetq_lane_u64(v2, 1)))
#define VEC_OR(v1, v2) ((v1) | (v2))
#else
#define VECTYPE unsigned long
#define SPLAT(p) (*(p) * (~0UL / 255))
#define ALL_EQ(v1, v2) ((v1) == (v2))
#define VEC_OR(v1, v2) ((v1) | (v2))
#endif
#define BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR 8
static bool
can_use_buffer_find_nonzero_offset_inner(const void *buf, size_t len)
{
return (len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
* sizeof(VECTYPE)) == 0
&& ((uintptr_t) buf) % sizeof(VECTYPE) == 0);
}
/*
* Searches for an area with non-zero content in a buffer
*
* Attention! The len must be a multiple of
* BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR * sizeof(VECTYPE)
* and addr must be a multiple of sizeof(VECTYPE) due to
* restriction of optimizations in this function.
*
* can_use_buffer_find_nonzero_offset_inner() can be used to
* check these requirements.
*
* The return value is the offset of the non-zero area rounded
* down to a multiple of sizeof(VECTYPE) for the first
* BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR chunks and down to
* BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR * sizeof(VECTYPE)
* afterwards.
*
* If the buffer is all zero the return value is equal to len.
*/
static size_t buffer_find_nonzero_offset_inner(const void *buf, size_t len)
{
const VECTYPE *p = buf;
const VECTYPE zero = (VECTYPE){0};
size_t i;
assert(can_use_buffer_find_nonzero_offset_inner(buf, len));
if (!len) {
return 0;
}
for (i = 0; i < BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR; i++) {
if (!ALL_EQ(p[i], zero)) {
return i * sizeof(VECTYPE);
}
}
for (i = BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR;
i < len / sizeof(VECTYPE);
i += BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR) {
VECTYPE tmp0 = VEC_OR(p[i + 0], p[i + 1]);
VECTYPE tmp1 = VEC_OR(p[i + 2], p[i + 3]);
VECTYPE tmp2 = VEC_OR(p[i + 4], p[i + 5]);
VECTYPE tmp3 = VEC_OR(p[i + 6], p[i + 7]);
VECTYPE tmp01 = VEC_OR(tmp0, tmp1);
VECTYPE tmp23 = VEC_OR(tmp2, tmp3);
if (!ALL_EQ(VEC_OR(tmp01, tmp23), zero)) {
break;
}
}
return i * sizeof(VECTYPE);
}
#if defined CONFIG_AVX2_OPT
#pragma GCC push_options
#pragma GCC target("avx2")
#include <cpuid.h>
#include <immintrin.h>
#define AVX2_VECTYPE __m256i
#define AVX2_SPLAT(p) _mm256_set1_epi8(*(p))
#define AVX2_ALL_EQ(v1, v2) \
(_mm256_movemask_epi8(_mm256_cmpeq_epi8(v1, v2)) == 0xFFFFFFFF)
#define AVX2_VEC_OR(v1, v2) (_mm256_or_si256(v1, v2))
static bool
can_use_buffer_find_nonzero_offset_avx2(const void *buf, size_t len)
{
return (len % (BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
* sizeof(AVX2_VECTYPE)) == 0
&& ((uintptr_t) buf) % sizeof(AVX2_VECTYPE) == 0);
}
static size_t buffer_find_nonzero_offset_avx2(const void *buf, size_t len)
{
const AVX2_VECTYPE *p = buf;
const AVX2_VECTYPE zero = (AVX2_VECTYPE){0};
size_t i;
assert(can_use_buffer_find_nonzero_offset_avx2(buf, len));
if (!len) {
return 0;
}
for (i = 0; i < BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR; i++) {
if (!AVX2_ALL_EQ(p[i], zero)) {
return i * sizeof(AVX2_VECTYPE);
}
}
for (i = BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR;
i < len / sizeof(AVX2_VECTYPE);
i += BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR) {
AVX2_VECTYPE tmp0 = AVX2_VEC_OR(p[i + 0], p[i + 1]);
AVX2_VECTYPE tmp1 = AVX2_VEC_OR(p[i + 2], p[i + 3]);
AVX2_VECTYPE tmp2 = AVX2_VEC_OR(p[i + 4], p[i + 5]);
AVX2_VECTYPE tmp3 = AVX2_VEC_OR(p[i + 6], p[i + 7]);
AVX2_VECTYPE tmp01 = AVX2_VEC_OR(tmp0, tmp1);
AVX2_VECTYPE tmp23 = AVX2_VEC_OR(tmp2, tmp3);
if (!AVX2_ALL_EQ(AVX2_VEC_OR(tmp01, tmp23), zero)) {
break;
}
}
return i * sizeof(AVX2_VECTYPE);
}
static bool avx2_support(void)
{
int a, b, c, d;
if (__get_cpuid_max(0, NULL) < 7) {
return false;
}
__cpuid_count(7, 0, a, b, c, d);
return b & bit_AVX2;
}
bool can_use_buffer_find_nonzero_offset(const void *buf, size_t len) \
__attribute__ ((ifunc("can_use_buffer_find_nonzero_offset_ifunc")));
size_t buffer_find_nonzero_offset(const void *buf, size_t len) \
__attribute__ ((ifunc("buffer_find_nonzero_offset_ifunc")));
static void *buffer_find_nonzero_offset_ifunc(void)
{
typeof(buffer_find_nonzero_offset) *func = (avx2_support()) ?
buffer_find_nonzero_offset_avx2 : buffer_find_nonzero_offset_inner;
return func;
}
static void *can_use_buffer_find_nonzero_offset_ifunc(void)
{
typeof(can_use_buffer_find_nonzero_offset) *func = (avx2_support()) ?
can_use_buffer_find_nonzero_offset_avx2 :
can_use_buffer_find_nonzero_offset_inner;
return func;
}
#pragma GCC pop_options
#else
bool can_use_buffer_find_nonzero_offset(const void *buf, size_t len)
{
return can_use_buffer_find_nonzero_offset_inner(buf, len);
}
size_t buffer_find_nonzero_offset(const void *buf, size_t len)
{
return buffer_find_nonzero_offset_inner(buf, len);
}
#endif
/*
* Checks if a buffer is all zeroes
*
* Attention! The len must be a multiple of 4 * sizeof(long) due to
* restriction of optimizations in this function.
*/
bool buffer_is_zero(const void *buf, size_t len)
{
/*
* Use long as the biggest available internal data type that fits into the
* CPU register and unroll the loop to smooth out the effect of memory
* latency.
*/
size_t i;
long d0, d1, d2, d3;
const long * const data = buf;
/* use vector optimized zero check if possible */
if (can_use_buffer_find_nonzero_offset(buf, len)) {
return buffer_find_nonzero_offset(buf, len) == len;
}
assert(len % (4 * sizeof(long)) == 0);
len /= sizeof(long);
for (i = 0; i < len; i += 4) {
d0 = data[i + 0];
d1 = data[i + 1];
d2 = data[i + 2];
d3 = data[i + 3];
if (d0 || d1 || d2 || d3) {
return false;
}
}
return true;
}
#ifndef _WIN32
/* Sets a specific flag */
int fcntl_setfl(int fd, int flag)