1 .\" Copyright (c) 2023 The FreeBSD Foundation
3 .\" This documentation was written by Robert Clausecker <fuz@FreeBSD.org>
4 .\" under sponsorship from the FreeBSD Foundation.
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35 On some architectures, the
38 provides enhanced implementations of commonly used functions, replacing
39 the architecture-independent implementations used otherwise.
40 Depending on architecture and function, an enhanced
41 implementation of a function may either always be used or the
43 detects at runtime which SIMD instruction set extensions are
44 supported and picks the most suitable implementation automatically.
47 the environment variable
49 can be used to override this mechanism.
51 Enhanced functions are present in the following architectures:
52 .Bl -column FUNCTION__ aarch64_ arm_ amd64_ i386_ ppc64_ -offset indent
53 .It Em FUNCTION Ta Em AARCH64 Ta Em ARM Ta Em AMD64 Ta Em I386 Ta Em PPC64
54 .It bcmp Ta Ta Ta S Ta S
55 .It bcopy Ta Ta S Ta S Ta S Ta SV
56 .It bzero Ta Ta S Ta S Ta S
57 .It div Ta Ta Ta S Ta S
58 .It index Ta S Ta Ta S1
59 .It ldiv Ta Ta Ta S Ta S
61 .It memcmp Ta Ta S Ta S Ta S
62 .It memcpy Ta S Ta S Ta S Ta S Ta SV
63 .It memmove Ta S Ta S Ta S Ta S Ta SV
64 .It memset Ta Ta S Ta S Ta S
67 .It strcat Ta Ta Ta S Ta S
68 .It strchr Ta S Ta Ta S1 Ta S
69 .It strchrnul Ta Ta Ta S1
70 .It strcmp Ta Ta S Ta S Ta S
71 .It strcpy Ta Ta Ta S Ta S Ta S2
72 .It strlen Ta Ta S Ta S1
73 .It strncmp Ta Ta S Ta Ta S
74 .It strncpy Ta Ta Ta Ta Ta S2
75 .It strrchr Ta S Ta Ta Ta S
76 .It swab Ta Ta Ta Ta S
77 .It wcschr Ta Ta Ta Ta S
78 .It wcscmp Ta Ta Ta Ta S
79 .It wcslen Ta Ta Ta Ta S
80 .It wmemchr Ta Ta Ta Ta S
83 .Sy S Ns :\ scalar (non-SIMD),
84 .Sy 1 Ns :\ amd64 baseline,
87 .Sy 3 Ns :\ x86-64-v3,
88 .Sy 4 Ns :\ x86-64-v4,
89 .Sy V Ns :\ PowerPC\ VSX.
96 controls the level of SIMD enhancements used.
97 If this variable is set to an architecture level from the list below
98 and that architecture level is supported by the processor, SIMD
104 is unset, not recognised, or not supported by the processor, the highest
105 level of SIMD enhancements supported by the processor is used.
107 A suffix beginning with
113 is ignored and may be used for future extensions.
114 The architecture level can be prefixed with a
116 character to force use of the requested architecture level, even if the
117 processor does not advertise that it is supported.
118 This usually causes applications to crash and should only be used for
119 testing purposes or if architecture level detection yields incorrect
122 The architecture levels follow the AMD64 SysV ABI supplement:
123 .Bl -tag -width x86-64-v2
125 scalar enhancements only (no SIMD)
127 cmov, cx8, x87 FPU, fxsr, MMX, osfxsr, SSE, SSE2
129 cx16, lahf/sahf, popcnt, SSE3, SSSE3, SSE4.1, SSE4.2
131 AVX, AVX2, BMI1, BMI2, F16C, FMA, lzcnt, movbe, osxsave
139 .It "Illegal Instruction"
142 if a command is terminated through delivery of a
147 Use of an unsupported architecture level was forced by setting
149 to a string beginning with a
151 character, causing a process to crash due to use of an unsupported
157 prefix or select a supported architecture level.
159 Message may also appear for unrelated reasons.
169 .%A Jan Hubi\[u010D]ka \" \(vc
172 .%B System V Application Binary Interface
174 .%T AMD64 Architecture Processor Supplement
179 Architecture-specific enhanced
181 functions were added starting
199 SIMD-enhanced functions were first added with
210 manual page appeared in
214 .An Robert Clausecker Aq Mt fuz@FreeBSD.org
219 such as cryptographic routines in the kernel or in
220 OpenSSL may also use SIMD enhancements.
221 These enhancements are not subject to the
223 variable and may have their own configuration
227 Use of SIMD enhancements cannot be configured on powerpc64.