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author | Richard Henderson <richard.henderson@linaro.org> | 2024-06-05 20:58:37 -0700 |
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committer | Richard Henderson <richard.henderson@linaro.org> | 2024-06-19 12:47:11 -0700 |
commit | 2d32a5d2a06a524c5e7967f918c406ec99418a34 (patch) | |
tree | d042442e48299e2964ff1d77c076e730f73e5182 /host | |
parent | 6b0ca412e16dae52bf1ef2da9436d4d8c81759f2 (diff) | |
download | qemu-2d32a5d2a06a524c5e7967f918c406ec99418a34.zip qemu-2d32a5d2a06a524c5e7967f918c406ec99418a34.tar.gz qemu-2d32a5d2a06a524c5e7967f918c406ec99418a34.tar.bz2 |
util/bufferiszero: Split out host include files
Split out host/bufferiszero.h.inc for x86, aarch64 and generic
in order to avoid an overlong ifdef ladder.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'host')
-rw-r--r-- | host/include/aarch64/host/bufferiszero.c.inc | 76 | ||||
-rw-r--r-- | host/include/generic/host/bufferiszero.c.inc | 10 | ||||
-rw-r--r-- | host/include/i386/host/bufferiszero.c.inc | 124 | ||||
-rw-r--r-- | host/include/x86_64/host/bufferiszero.c.inc | 1 |
4 files changed, 211 insertions, 0 deletions
diff --git a/host/include/aarch64/host/bufferiszero.c.inc b/host/include/aarch64/host/bufferiszero.c.inc new file mode 100644 index 0000000..947ee7c --- /dev/null +++ b/host/include/aarch64/host/bufferiszero.c.inc @@ -0,0 +1,76 @@ +/* + * SPDX-License-Identifier: GPL-2.0-or-later + * buffer_is_zero acceleration, aarch64 version. + */ + +#ifdef __ARM_NEON +#include <arm_neon.h> + +/* + * Helper for preventing the compiler from reassociating + * chains of binary vector operations. + */ +#define REASSOC_BARRIER(vec0, vec1) asm("" : "+w"(vec0), "+w"(vec1)) + +static bool buffer_is_zero_simd(const void *buf, size_t len) +{ + uint32x4_t t0, t1, t2, t3; + + /* Align head/tail to 16-byte boundaries. */ + const uint32x4_t *p = QEMU_ALIGN_PTR_DOWN(buf + 16, 16); + const uint32x4_t *e = QEMU_ALIGN_PTR_DOWN(buf + len - 1, 16); + + /* Unaligned loads at head/tail. */ + t0 = vld1q_u32(buf) | vld1q_u32(buf + len - 16); + + /* Collect a partial block at tail end. */ + t1 = e[-7] | e[-6]; + t2 = e[-5] | e[-4]; + t3 = e[-3] | e[-2]; + t0 |= e[-1]; + REASSOC_BARRIER(t0, t1); + REASSOC_BARRIER(t2, t3); + t0 |= t1; + t2 |= t3; + REASSOC_BARRIER(t0, t2); + t0 |= t2; + + /* + * Loop over complete 128-byte blocks. + * With the head and tail removed, e - p >= 14, so the loop + * must iterate at least once. + */ + do { + /* + * Reduce via UMAXV. Whatever the actual result, + * it will only be zero if all input bytes are zero. + */ + if (unlikely(vmaxvq_u32(t0) != 0)) { + return false; + } + + t0 = p[0] | p[1]; + t1 = p[2] | p[3]; + t2 = p[4] | p[5]; + t3 = p[6] | p[7]; + REASSOC_BARRIER(t0, t1); + REASSOC_BARRIER(t2, t3); + t0 |= t1; + t2 |= t3; + REASSOC_BARRIER(t0, t2); + t0 |= t2; + p += 8; + } while (p < e - 7); + + return vmaxvq_u32(t0) == 0; +} + +static biz_accel_fn const accel_table[] = { + buffer_is_zero_int_ge256, + buffer_is_zero_simd, +}; + +#define best_accel() 1 +#else +# include "host/include/generic/host/bufferiszero.c.inc" +#endif diff --git a/host/include/generic/host/bufferiszero.c.inc b/host/include/generic/host/bufferiszero.c.inc new file mode 100644 index 0000000..ea0875c --- /dev/null +++ b/host/include/generic/host/bufferiszero.c.inc @@ -0,0 +1,10 @@ +/* + * SPDX-License-Identifier: GPL-2.0-or-later + * buffer_is_zero acceleration, generic version. + */ + +static biz_accel_fn const accel_table[1] = { + buffer_is_zero_int_ge256 +}; + +#define best_accel() 0 diff --git a/host/include/i386/host/bufferiszero.c.inc b/host/include/i386/host/bufferiszero.c.inc new file mode 100644 index 0000000..3b9605d --- /dev/null +++ b/host/include/i386/host/bufferiszero.c.inc @@ -0,0 +1,124 @@ +/* + * SPDX-License-Identifier: GPL-2.0-or-later + * buffer_is_zero acceleration, x86 version. + */ + +#if defined(CONFIG_AVX2_OPT) || defined(__SSE2__) +#include <immintrin.h> + +/* Helper for preventing the compiler from reassociating + chains of binary vector operations. */ +#define SSE_REASSOC_BARRIER(vec0, vec1) asm("" : "+x"(vec0), "+x"(vec1)) + +/* Note that these vectorized functions may assume len >= 256. */ + +static bool __attribute__((target("sse2"))) +buffer_zero_sse2(const void *buf, size_t len) +{ + /* Unaligned loads at head/tail. */ + __m128i v = *(__m128i_u *)(buf); + __m128i w = *(__m128i_u *)(buf + len - 16); + /* Align head/tail to 16-byte boundaries. */ + const __m128i *p = QEMU_ALIGN_PTR_DOWN(buf + 16, 16); + const __m128i *e = QEMU_ALIGN_PTR_DOWN(buf + len - 1, 16); + __m128i zero = { 0 }; + + /* Collect a partial block at tail end. */ + v |= e[-1]; w |= e[-2]; + SSE_REASSOC_BARRIER(v, w); + v |= e[-3]; w |= e[-4]; + SSE_REASSOC_BARRIER(v, w); + v |= e[-5]; w |= e[-6]; + SSE_REASSOC_BARRIER(v, w); + v |= e[-7]; v |= w; + + /* + * Loop over complete 128-byte blocks. + * With the head and tail removed, e - p >= 14, so the loop + * must iterate at least once. + */ + do { + v = _mm_cmpeq_epi8(v, zero); + if (unlikely(_mm_movemask_epi8(v) != 0xFFFF)) { + return false; + } + v = p[0]; w = p[1]; + SSE_REASSOC_BARRIER(v, w); + v |= p[2]; w |= p[3]; + SSE_REASSOC_BARRIER(v, w); + v |= p[4]; w |= p[5]; + SSE_REASSOC_BARRIER(v, w); + v |= p[6]; w |= p[7]; + SSE_REASSOC_BARRIER(v, w); + v |= w; + p += 8; + } while (p < e - 7); + + return _mm_movemask_epi8(_mm_cmpeq_epi8(v, zero)) == 0xFFFF; +} + +#ifdef CONFIG_AVX2_OPT +static bool __attribute__((target("avx2"))) +buffer_zero_avx2(const void *buf, size_t len) +{ + /* Unaligned loads at head/tail. */ + __m256i v = *(__m256i_u *)(buf); + __m256i w = *(__m256i_u *)(buf + len - 32); + /* Align head/tail to 32-byte boundaries. */ + const __m256i *p = QEMU_ALIGN_PTR_DOWN(buf + 32, 32); + const __m256i *e = QEMU_ALIGN_PTR_DOWN(buf + len - 1, 32); + __m256i zero = { 0 }; + + /* Collect a partial block at tail end. */ + v |= e[-1]; w |= e[-2]; + SSE_REASSOC_BARRIER(v, w); + v |= e[-3]; w |= e[-4]; + SSE_REASSOC_BARRIER(v, w); + v |= e[-5]; w |= e[-6]; + SSE_REASSOC_BARRIER(v, w); + v |= e[-7]; v |= w; + + /* Loop over complete 256-byte blocks. */ + for (; p < e - 7; p += 8) { + /* PTEST is not profitable here. */ + v = _mm256_cmpeq_epi8(v, zero); + if (unlikely(_mm256_movemask_epi8(v) != 0xFFFFFFFF)) { + return false; + } + v = p[0]; w = p[1]; + SSE_REASSOC_BARRIER(v, w); + v |= p[2]; w |= p[3]; + SSE_REASSOC_BARRIER(v, w); + v |= p[4]; w |= p[5]; + SSE_REASSOC_BARRIER(v, w); + v |= p[6]; w |= p[7]; + SSE_REASSOC_BARRIER(v, w); + v |= w; + } + + return _mm256_movemask_epi8(_mm256_cmpeq_epi8(v, zero)) == 0xFFFFFFFF; +} +#endif /* CONFIG_AVX2_OPT */ + +static biz_accel_fn const accel_table[] = { + buffer_is_zero_int_ge256, + buffer_zero_sse2, +#ifdef CONFIG_AVX2_OPT + buffer_zero_avx2, +#endif +}; + +static unsigned best_accel(void) +{ +#ifdef CONFIG_AVX2_OPT + unsigned info = cpuinfo_init(); + if (info & CPUINFO_AVX2) { + return 2; + } +#endif + return 1; +} + +#else +# include "host/include/generic/host/bufferiszero.c.inc" +#endif diff --git a/host/include/x86_64/host/bufferiszero.c.inc b/host/include/x86_64/host/bufferiszero.c.inc new file mode 100644 index 0000000..1d3f1fd --- /dev/null +++ b/host/include/x86_64/host/bufferiszero.c.inc @@ -0,0 +1 @@ +#include "host/include/i386/host/bufferiszero.c.inc" |