FreeBSD Manual Pages
SIMD(7) Miscellaneous Information Manual SIMD(7) NAME simd -- SIMD enhancements DESCRIPTION On some architectures, the FreeBSD libc provides enhanced implementations of commonly used functions, replacing the architecture-independent imple- mentations used otherwise. Depending on architecture and function, an en- hanced implementation of a function may either always be used or the libc detects at runtime which SIMD instruction set extensions are supported and picks the most suitable implementation automatically. On amd64, the envi- ronment variable ARCHLEVEL can be used to override this mechanism. Enhanced functions are present for the following architectures: FUNCTION AARCH64 ARM AMD64 I386 PPC64 RISC-V bcmp A S1 S bcopy A S S S SV S bzero A S S S S div S S index A S1 S ldiv S S lldiv S memchr A S1 S memcmp A S S1 S memccpy A S1 memcpy A S S S SV S memmove A S S S SV memrchr A S1 memset A S S S S rindex A S1 S S stpcpy A S1 stpncpy S1 strcat A S1 S strchr A S1 S S strchrnul A S1 S strcmp A S S1 S strcpy A S1 S S2 strcspn S S2 strlcat A S1 strlcpy A S1 strlen A S S1 S strncat A S1 strncmp A S S1 S strncpy S1 S2 strnlen A S1 S strrchr A S1 S S strpbrk S S2 strsep S S2 strspn S S2 swab S timingsafe_bcmp A S1 timingsafe_memcmp S S wcschr S wcscmp S wcslen S wmemchr S S: scalar (non-SIMD), 1: amd64 baseline, 2: x86-64-v2 or PowerPC 2.05, 3: x86-64-v3, 4: x86-64-v4, V: PowerPC VSX, A: Arm ASIMD (NEON). ENVIRONMENT ARCHLEVEL On amd64, controls the level of SIMD enhancements used. If this variable is set to an architecture level from the list below and that architecture level is supported by the processor, SIMD en- hancements up to ARCHLEVEL are used. If ARCHLEVEL is unset, not recognised, or not supported by the processor, the highest level of SIMD enhancements supported by the processor is used. A suffix beginning with `': or `+' in ARCHLEVEL is ignored and may be used for future extensions. The architecture level can be pre- fixed with a `'! character to force use of the requested architec- ture level, even if the processor does not advertise that it is supported. This usually causes applications to crash and should only be used for testing purposes or if architecture level detec- tion yields incorrect results. The architecture levels follow the AMD64 SysV ABI supplement: scalar scalar enhancements only (no SIMD) baseline cmov, cx8, x87 FPU, fxsr, MMX, osfxsr, SSE, SSE2 x86-64-v2 cx16, lahf/sahf, popcnt, SSE3, SSSE3, SSE4.1, SSE4.2 x86-64-v3 AVX, AVX2, BMI1, BMI2, F16C, FMA, lzcnt, movbe, osxsave x86-64-v4 AVX-512F/BW/CD/DQ/VL DIAGNOSTICS Illegal Instruction Printed by sh(1) if a command is terminated through delivery of a SIGILL signal, see signal(3). Use of an unsupported architecture level was forced by setting ARCHLEVEL to a string beginning with a `'! character, causing a process to crash due to use of an unsupported instruction. Unset ARCHLEVEL, remove the `'! prefix or select a supported architecture level. Message may also appear for unrelated reasons. SEE ALSO string(3), arch(7) H. J. Lu, Michael Matz, Milind Girkar, Jan Hubivka, Andreas Jaeger, and Mark Mitchell, "AMD64 Architecture Processor Supplement", System V Applica- tion Binary Interface, May 23, 2023, Version 1.0. HISTORY Architecture-specific enhanced libc functions were added starting with FreeBSD 2.0 for i386, FreeBSD 6.0 for arm, FreeBSD 6.1 for amd64, FreeBSD 11.0 for aarch64, FreeBSD 12.0 for powerpc64, and FreeBSD 16.0 for riscv64. SIMD-enhanced functions were first added with FreeBSD 13.0 for powerpc64 and with FreeBSD 14.1 for amd64. A simd manual page appeared in FreeBSD 14.1. AUTHOR Robert Clausecker <fuz@FreeBSD.org> CAVEATS Other parts of FreeBSD such as cryptographic routines in the kernel or in OpenSSL may also use SIMD enhancements. These enhancements are not subject to the ARCHLEVEL variable and may have their own configuration mechanism. BUGS Use of SIMD enhancements cannot be configured on powerpc64. FreeBSD ports 15.quarterly October 21, 2025 SIMD(7)
NAME | DESCRIPTION | ENVIRONMENT | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHOR | CAVEATS | BUGS
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