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https://github.com/FFmpeg/FFmpeg.git
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f032234953
This is not actually used for anything. The configure check causes the CPU feature flag to be set, but nothing consumes it at all. While AArch64 does have VFP, it is only used for the scalar C code. Conversely, it is still possible to disable VFP, by changing the C compiler flags as before (though that only makes sense for an hypothetical non-standard Armv8 platform without VFP). Note that this retains the "vfp" option flag, for backward compatibility and on the very remote but theoretically possible chance that FFmpeg actually makes use of it in the future. AV_CPU_FLAG_VFP is retained as it is actually used by AArch32.
133 lines
3.4 KiB
C
133 lines
3.4 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/cpu.h"
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#include "libavutil/cpu_internal.h"
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#include "config.h"
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#if (defined(__linux__) || defined(__ANDROID__)) && HAVE_GETAUXVAL && HAVE_ASM_HWCAP_H
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#include <stdint.h>
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#include <asm/hwcap.h>
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#include <sys/auxv.h>
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#define get_cpu_feature_reg(reg, val) \
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__asm__("mrs %0, " #reg : "=r" (val))
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static int detect_flags(void)
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{
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int flags = 0;
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unsigned long hwcap;
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hwcap = getauxval(AT_HWCAP);
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#if defined(HWCAP_CPUID)
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// We can check for DOTPROD and I8MM using HWCAP_ASIMDDP and
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// HWCAP2_I8MM too, avoiding to read the CPUID registers (which triggers
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// a trap, handled by the kernel). However the HWCAP_* defines for these
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// extensions are added much later than HWCAP_CPUID, so the userland
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// headers might lack support for them even if the binary later is run
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// on hardware that does support it (and where the kernel might support
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// HWCAP_CPUID).
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// See https://www.kernel.org/doc/html/latest/arm64/cpu-feature-registers.html
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if (hwcap & HWCAP_CPUID) {
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uint64_t tmp;
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get_cpu_feature_reg(ID_AA64ISAR0_EL1, tmp);
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if (((tmp >> 44) & 0xf) == 0x1)
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flags |= AV_CPU_FLAG_DOTPROD;
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get_cpu_feature_reg(ID_AA64ISAR1_EL1, tmp);
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if (((tmp >> 52) & 0xf) == 0x1)
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flags |= AV_CPU_FLAG_I8MM;
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}
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#else
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(void)hwcap;
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#endif
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return flags;
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}
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#elif defined(__APPLE__) && HAVE_SYSCTLBYNAME
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#include <sys/sysctl.h>
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static int detect_flags(void)
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{
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uint32_t value = 0;
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size_t size;
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int flags = 0;
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size = sizeof(value);
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if (!sysctlbyname("hw.optional.arm.FEAT_DotProd", &value, &size, NULL, 0)) {
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if (value)
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flags |= AV_CPU_FLAG_DOTPROD;
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}
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size = sizeof(value);
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if (!sysctlbyname("hw.optional.arm.FEAT_I8MM", &value, &size, NULL, 0)) {
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if (value)
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flags |= AV_CPU_FLAG_I8MM;
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}
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return flags;
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}
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#elif defined(_WIN32)
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#include <windows.h>
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static int detect_flags(void)
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{
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int flags = 0;
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#ifdef PF_ARM_V82_DP_INSTRUCTIONS_AVAILABLE
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if (IsProcessorFeaturePresent(PF_ARM_V82_DP_INSTRUCTIONS_AVAILABLE))
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flags |= AV_CPU_FLAG_DOTPROD;
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#endif
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return flags;
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}
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#else
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static int detect_flags(void)
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{
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return 0;
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}
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#endif
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int ff_get_cpu_flags_aarch64(void)
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{
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int flags = AV_CPU_FLAG_ARMV8 * HAVE_ARMV8 |
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AV_CPU_FLAG_NEON * HAVE_NEON;
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#ifdef __ARM_FEATURE_DOTPROD
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flags |= AV_CPU_FLAG_DOTPROD;
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#endif
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#ifdef __ARM_FEATURE_MATMUL_INT8
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flags |= AV_CPU_FLAG_I8MM;
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#endif
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flags |= detect_flags();
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return flags;
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}
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size_t ff_get_cpu_max_align_aarch64(void)
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{
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int flags = av_get_cpu_flags();
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if (flags & AV_CPU_FLAG_NEON)
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return 16;
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return 8;
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}
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