错误:未在此范围内声明"_mm512_loadu_epi64" [英] error: '_mm512_loadu_epi64' was not declared in this scope
问题描述
我正在尝试为此问题报告创建一个最小的复制器. AVX-512似乎存在一些问题,该产品已在装有Skylake处理器的最新Apple机器上发货.
I'm trying to create a minimal reproducer for this issue report. There seems to be some problems with AVX-512, which is shipping on the latest Apple machines with Skylake processors.
根据 GCC6发行说明,AVX-512齿轮应该可用.根据英特尔内在指南 vmovdqu64
可与AVX-512VL
和AVX-512F
:
According to GCC6 release notes the AVX-512 gear should be available. According to the Intel Intrinsics Guide vmovdqu64
is available with AVX-512VL
and AVX-512F
:
$ cat test.cxx
#include <cstdint>
#include <immintrin.h>
int main(int argc, char* argv[])
{
uint64_t x[8];
__m512i y = _mm512_loadu_epi64(x);
return 0;
}
然后:
$ /opt/local/bin/g++-mp-6 -mavx512f -Wa,-q test.cxx -o test.exe
test.cxx: In function 'int main(int, char**)':
test.cxx:6:37: error: '_mm512_loadu_epi64' was not declared in this scope
__m512i y = _mm512_loadu_epi64(x);
^
$ /opt/local/bin/g++-mp-6 -mavx -mavx2 -mavx512f -Wa,-q test.cxx -o test.exe
test.cxx: In function 'int main(int, char**)':
test.cxx:6:37: error: '_mm512_loadu_epi64' was not declared in this scope
__m512i y = _mm512_loadu_epi64(x);
^
$ /opt/local/bin/g++-mp-6 -msse4.1 -msse4.2 -mavx -mavx2 -mavx512f -Wa,-q test.cxx -o test.exe
test.cxx: In function 'int main(int, char**)':
test.cxx:6:37: error: '_mm512_loadu_epi64' was not declared in this scope
__m512i y = _mm512_loadu_epi64(x);
^
我没有成功将选项移回-msse2
.我似乎丢失了一些东西.
I walked the options back to -msse2
without success. I seem to be missing something.
使用AVX-512进行现代GCC需要什么?
What is required to engage AVX-512 for modern GCC?
根据/opt/local/bin/g++-mp-6 -v
,以下是标题搜索路径:
According to a /opt/local/bin/g++-mp-6 -v
, these are the header search paths:
#include "..." search starts here:
#include <...> search starts here:
/opt/local/include/gcc6/c++/
/opt/local/include/gcc6/c++//x86_64-apple-darwin13
/opt/local/include/gcc6/c++//backward
/opt/local/lib/gcc6/gcc/x86_64-apple-darwin13/6.5.0/include
/opt/local/include
/opt/local/lib/gcc6/gcc/x86_64-apple-darwin13/6.5.0/include-fixed
/usr/include
/System/Library/Frameworks
/Library/Frameworks
然后:
$ grep -R '_mm512_' /opt/local/lib/gcc6/ | grep avx512f | head -n 8
/opt/local/lib/gcc6//gcc/x86_64-apple-darwin13/6.5.0/include/avx512fintrin.h:_mm512_set_epi64 (long long __A, long long __B, long long __C,
/opt/local/lib/gcc6//gcc/x86_64-apple-darwin13/6.5.0/include/avx512fintrin.h:_mm512_set_epi32 (int __A, int __B, int __C, int __D,
/opt/local/lib/gcc6//gcc/x86_64-apple-darwin13/6.5.0/include/avx512fintrin.h:_mm512_set_pd (double __A, double __B, double __C, double __D,
/opt/local/lib/gcc6//gcc/x86_64-apple-darwin13/6.5.0/include/avx512fintrin.h:_mm512_set_ps (float __A, float __B, float __C, float __D,
/opt/local/lib/gcc6//gcc/x86_64-apple-darwin13/6.5.0/include/avx512fintrin.h:#define _mm512_setr_epi64(e0,e1,e2,e3,e4,e5,e6,e7) \
/opt/local/lib/gcc6//gcc/x86_64-apple-darwin13/6.5.0/include/avx512fintrin.h: _mm512_set_epi64(e7,e6,e5,e4,e3,e2,e1,e0)
/opt/local/lib/gcc6//gcc/x86_64-apple-darwin13/6.5.0/include/avx512fintrin.h:#define _mm512_setr_epi32(e0,e1,e2,e3,e4,e5,e6,e7, \
/opt/local/lib/gcc6//gcc/x86_64-apple-darwin13/6.5.0/include/avx512fintrin.h: _mm512_set_epi32(e15,e14,e13,e12,e11,e10,e9,e8,e7,e6,e5,e4,e3,e2,e1,e0)
...
推荐答案
在没有任何屏蔽的情况下,没有理由使用此内在函数或使用它代替等效的_mm512_loadu_si512
.这只是令人困惑,并且可能使人类读者误以为这是单个epi64
的vmovq
零扩展负载.
Intel's intrinsics finder does specify that it exists, but even current trunk gcc (on Godbolt) doesn't define it.
几乎所有AVX512指令都支持合并屏蔽和零屏蔽.以前纯粹是按位/完整寄存器的指令,现在没有有意义的元素边界,现在有32位和64位元素风格,如vpxord
和vpxorq
.或 vmovdqa32
和vmovdqa64
.但是使用没有屏蔽的任何版本仍然只是正常的向量加载/存储/寄存器复制,并且在带有内在函数的C ++源代码中为它们指定元素大小的任何内容(仅包含向量的总宽度)是没有意义的.
Almost all AVX512 instructions support merge-masking and zero-masking. Instructions that used to be purely bitwise / whole-register with no meaningful element boundaries now come in 32 and 64-bit element flavours, like vpxord
and vpxorq
. Or vmovdqa32
and vmovdqa64
. But using either version with no masking is still just a normal vector load / store / register-copy, and it's not meaningful to specify anything about element-size for them in the C++ source with intrinsics, only the total vector width.
另请参见 _mm512_load_epi32和_mm512_load_si512之间有什么区别?
SSE *和AVX1/2选项与GCC标头是否根据gcc内置定义此内在函数无关. -mavx512f
已经暗示了AVX512之前的所有Intel SSE/AVX扩展.
SSE* and AVX1/2 options are irrelevent to whether or not GCC headers define this intrinsic in terms of gcc built-ins or not; -mavx512f
already implies all of the Intel SSE/AVX extensions before AVX512.
它存在于clang干线中(但不存在7.0,所以它是最近才添加的.)
It is present in clang trunk (but not 7.0 so it was only very recently added).
- 未对齐的
_mm512_loadu_si512
-各处均受支持,请使用此 - 未对齐的
_mm512_loadu_epi64
-lang声,而不是gcc. - 对齐的
_mm512_load_si512
-各地都受支持,请使用此 - 对齐的
_mm512_load_epi64
-到处都得到支持,令人惊讶. - 未对齐的
_mm512_maskz_loadu_epi64
-各处均受支持,可将其用于零掩盖载荷 - 未对齐的
_mm512_mask_loadu_epi64
-各处均受支持,可将其用于合并掩码加载.
- unaligned
_mm512_loadu_si512
- supported everywhere, use this - unaligned
_mm512_loadu_epi64
- clang trunk, not gcc. - aligned
_mm512_load_si512
- supported everywhere, use this - aligned
_mm512_load_epi64
- also supported everywhere, surprisingly. - unaligned
_mm512_maskz_loadu_epi64
- supported everywhere, use this for zero-masked loads - unaligned
_mm512_mask_loadu_epi64
- supported everywhere, use this for merge-mask loads.
此代码最早可在-march=avx512f
上在gcc上于4.9.0上编译,而主线(Linux)则可在3.9上上进行编译.或者,如果他们支持,则为-march=skylake-avx512
或-march=knl
.我尚未使用Apple Clang进行测试.
This code compiles on gcc as early as 4.9.0, and mainline (Linux) clang as early as 3.9, both with -march=avx512f
. Or if they support it, -march=skylake-avx512
or -march=knl
. I haven't tested with Apple Clang.
#include <immintrin.h>
__m512i loadu_si512(void *x) { return _mm512_loadu_si512(x); }
__m512i load_epi64(void *x) { return _mm512_load_epi64(x); }
//__m512i loadu_epi64(void *x) { return _mm512_loadu_epi64(x); }
__m512i loadu_maskz(void *x) { return _mm512_maskz_loadu_epi64(0xf0, x); }
__m512i loadu_mask(void *x) { return _mm512_mask_loadu_epi64(_mm512_setzero_si512(), 0xf0, x); }
Godbolt link; you can uncomment the _mm512_loadu_epi64
and flip the compiler to clang trunk to see it work there.
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