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instrset.h
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instrset.h
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/**************************** instrset.h **********************************
* Author: Agner Fog
* Date created: 2012-05-30
* Last modified: 2023-12-02
* Version: 2.02.02
* Project: vector class library
* Description:
* Header file for various compiler-specific tasks as well as common
* macros and templates. This file contains:
*
* > Selection of the supported instruction set
* > Defines compiler version macros
* > Undefines certain macros that prevent function overloading
* > Helper functions that depend on instruction set, compiler, or platform
* > Common templates for permute, blend, etc.
*
* For instructions, see vcl_manual.pdf
*
* (c) Copyright 2012-2023 Agner Fog.
* Apache License version 2.0 or later.
******************************************************************************/
#ifndef INSTRSET_H
#define INSTRSET_H 20200
// check if compiled for C++17
#if defined(_MSVC_LANG) // MS compiler has its own version of __cplusplus with different value
#if _MSVC_LANG < 201703
#error Please compile for C++17 or higher
#endif
#else // all other compilers
#if __cplusplus < 201703
#error Please compile for C++17 or higher
#endif
#endif
// Allow the use of floating point permute instructions on integer vectors.
// Some CPU's have an extra latency of 1 or 2 clock cycles for this, but
// it may still be faster than alternative implementations:
#define ALLOW_FP_PERMUTE true
// Macro to indicate 64 bit mode
#if (defined(_M_AMD64) || defined(_M_X64) || defined(__amd64) ) && ! defined(__x86_64__)
#define __x86_64__ 1 // There are many different macros for this, decide on only one
#endif
// The following values of INSTRSET are currently defined:
// 2: SSE2
// 3: SSE3
// 4: SSSE3
// 5: SSE4.1
// 6: SSE4.2
// 7: AVX
// 8: AVX2
// 9: AVX512F
// 10: AVX512BW/DQ/VL
// In the future, INSTRSET = 11 may include AVX512VBMI and AVX512VBMI2, but this
// decision cannot be made before the market situation for CPUs with these
// instruction sets is better known
// Find instruction set from compiler macros if INSTRSET is not defined.
// Note: Some of these macros are not defined in Microsoft compilers
#ifndef INSTRSET
#if defined ( __AVX512VL__ ) && defined ( __AVX512BW__ ) && defined ( __AVX512DQ__ )
#define INSTRSET 10
#elif defined ( __AVX512F__ ) || defined ( __AVX512__ )
#define INSTRSET 9
#elif defined ( __AVX2__ )
#define INSTRSET 8
#elif defined ( __AVX__ )
#define INSTRSET 7
#elif defined ( __SSE4_2__ )
#define INSTRSET 6
#elif defined ( __SSE4_1__ )
#define INSTRSET 5
#elif defined ( __SSSE3__ )
#define INSTRSET 4
#elif defined ( __SSE3__ )
#define INSTRSET 3
#elif defined ( __SSE2__ ) || defined ( __x86_64__ )
#define INSTRSET 2
#elif defined ( __SSE__ )
#define INSTRSET 1
#elif defined ( _M_IX86_FP ) // Defined in MS compiler. 1: SSE, 2: SSE2
#define INSTRSET _M_IX86_FP
#else
#define INSTRSET 0
#endif // instruction set defines
#endif // INSTRSET
#if INSTRSET >= 8 && !defined(__FMA__)
// Assume that all processors that have AVX2 also have FMA3
#if defined (__GNUC__) && ! defined (__INTEL_COMPILER)
// Prevent error message in g++ and Clang when using FMA intrinsics with avx2:
#if !defined(DISABLE_WARNING_AVX2_WITHOUT_FMA)
#pragma message "It is recommended to specify also option -mfma when using -mavx2 or higher"
#endif
#elif ! defined (__clang__)
#define __FMA__ 1
#endif
#endif
// Header files for non-vector intrinsic functions including _BitScanReverse(int), __cpuid(int[4],int), _xgetbv(int)
#ifdef _MSC_VER // Microsoft compiler or compatible Intel compiler
#include <intrin.h>
#pragma warning(disable: 6323 4514 4710 4711) // Diasble annoying warnings
#else
#include <x86intrin.h> // Gcc or Clang compiler
#endif
#include <stdint.h> // Define integer types with known size
#include <limits.h> // Define INT_MAX
#include <stdlib.h> // define abs(int)
// functions in instrset_detect.cpp:
#ifdef VCL_NAMESPACE
namespace VCL_NAMESPACE {
#endif
int instrset_detect(void); // tells which instruction sets are supported
bool hasFMA3(void); // true if FMA3 instructions supported
bool hasFMA4(void); // true if FMA4 instructions supported
bool hasXOP(void); // true if XOP instructions supported
bool hasAVX512ER(void); // true if AVX512ER instructions supported
bool hasAVX512VBMI(void); // true if AVX512VBMI instructions supported
bool hasAVX512VBMI2(void); // true if AVX512VBMI2 instructions supported
bool hasF16C(void); // true if F16C instructions supported
bool hasAVX512FP16(void); // true if AVX512_FP16 instructions supported
// function in physical_processors.cpp:
int physicalProcessors(int * logical_processors = 0);
#ifdef VCL_NAMESPACE
}
#endif
// GCC version
#if defined(__GNUC__) && !defined (GCC_VERSION) && !defined (__clang__)
#define GCC_VERSION ((__GNUC__) * 10000 + (__GNUC_MINOR__) * 100 + (__GNUC_PATCHLEVEL__))
#endif
// Clang version
#if defined (__clang__)
#define CLANG_VERSION ((__clang_major__) * 10000 + (__clang_minor__) * 100 + (__clang_patchlevel__))
// Problem: The version number is not consistent across platforms
// http://llvm.org/bugs/show_bug.cgi?id=12643
// Apple bug 18746972
#endif
// Fix problem with non-overloadable macros named min and max in WinDef.h
#ifdef _MSC_VER
#if defined (_WINDEF_) && defined(min) && defined(max)
#undef min
#undef max
#endif
#ifndef NOMINMAX
#define NOMINMAX
#endif
// warning for poor support for AVX512F in MS compiler
#if !defined(__INTEL_COMPILER) && !defined(__clang__)
#if INSTRSET == 9
#pragma message("Warning: MS compiler cannot generate code for AVX512F without AVX512DQ")
#endif
#if _MSC_VER < 1920 && INSTRSET > 8
#pragma message("Warning: Your compiler has poor support for AVX512. Code may be erroneous.\nPlease use a newer compiler version or a different compiler!")
#endif
#endif // __INTEL_COMPILER
#endif // _MSC_VER
#if defined(__INTEL_COMPILER) && __INTEL_COMPILER < 2021
#error The Intel compiler version 19.00 cannot compile VCL version 2
#endif
/* Clang problem:
The Clang compiler treats the intrinsic vector types __m128, __m128i, and __m128d as identical.
See the bug report at https://bugs.llvm.org/show_bug.cgi?id=17164
Additional problem: The version number is not consistent across platforms. The Apple build has
different version numbers. We have to rely on __apple_build_version__ on the Mac platform:
http://llvm.org/bugs/show_bug.cgi?id=12643
We have to make switches here when - hopefully - the error some day has been fixed.
We need different version checks with and whithout __apple_build_version__
*/
#if (defined (__clang__) || defined(__apple_build_version__)) && !defined(__INTEL_COMPILER)
#define FIX_CLANG_VECTOR_ALIAS_AMBIGUITY
#endif
#if defined (__GNUC__) && __GNUC__ < 10 && !defined(__clang__)
// Gcc 9 and earlier donot have _mm256_zextsi128_si256 and similar functions for xero-extending vector registers
#define ZEXT_MISSING
#endif
#ifdef VCL_NAMESPACE
namespace VCL_NAMESPACE {
#endif
// Constant for indicating don't care in permute and blend functions.
// V_DC is -256 in Vector class library version 1.xx
// V_DC can be any value less than -1 in Vector class library version 2.00
constexpr int V_DC = -256;
/*****************************************************************************
*
* Helper functions that depend on instruction set, compiler, or platform
*
*****************************************************************************/
// Define interface to cpuid instruction.
// input: functionnumber = leaf (eax), ecxleaf = subleaf(ecx)
// output: output[0] = eax, output[1] = ebx, output[2] = ecx, output[3] = edx
static inline void cpuid(int output[4], int functionnumber, int ecxleaf = 0) {
#if defined(__GNUC__) || defined(__clang__) // use inline assembly, Gnu/AT&T syntax
int a, b, c, d;
__asm("cpuid" : "=a"(a), "=b"(b), "=c"(c), "=d"(d) : "a"(functionnumber), "c"(ecxleaf) : );
output[0] = a;
output[1] = b;
output[2] = c;
output[3] = d;
#elif defined (_MSC_VER) // Microsoft compiler, intrin.h included
__cpuidex(output, functionnumber, ecxleaf); // intrinsic function for CPUID
#else // unknown platform. try inline assembly with masm/intel syntax
__asm {
mov eax, functionnumber
mov ecx, ecxleaf
cpuid;
mov esi, output
mov[esi], eax
mov[esi + 4], ebx
mov[esi + 8], ecx
mov[esi + 12], edx
}
#endif
}
// Define popcount function. Gives sum of bits
#if INSTRSET >= 6 // SSE4.2
// The popcnt instruction is not officially part of the SSE4.2 instruction set,
// but available in all known processors with SSE4.2
static inline uint32_t vml_popcnt(uint32_t a) {
return (uint32_t)_mm_popcnt_u32(a); // Intel intrinsic. Supported by gcc and clang
}
#ifdef __x86_64__
static inline int64_t vml_popcnt(uint64_t a) {
return _mm_popcnt_u64(a); // Intel intrinsic.
}
#else // 32 bit mode
static inline int64_t vml_popcnt(uint64_t a) {
return _mm_popcnt_u32(uint32_t(a >> 32)) + _mm_popcnt_u32(uint32_t(a));
}
#endif
#else // no SSE4.2
static inline uint32_t vml_popcnt(uint32_t a) {
// popcnt instruction not available
uint32_t b = a - ((a >> 1) & 0x55555555);
uint32_t c = (b & 0x33333333) + ((b >> 2) & 0x33333333);
uint32_t d = (c + (c >> 4)) & 0x0F0F0F0F;
uint32_t e = d * 0x01010101;
return e >> 24;
}
static inline int32_t vml_popcnt(uint64_t a) {
return (int32_t)(vml_popcnt(uint32_t(a >> 32)) + vml_popcnt(uint32_t(a)));
}
#endif
// Define bit-scan-forward function. Gives index to lowest set bit
#if (defined (__GNUC__) || defined(__clang__)) && !defined (_MSC_VER)
// _BitScanForward intrinsics are defined only under Windows and only when _MSC_VER is defined
// Use inline assembly for gcc and Clang
#if defined(__clang_major__) && __clang_major__ < 10
// fix bug in Clang version 6. (not detected in version 8 and later)
// Clang version 6 uses a k register as parameter a when inlined from horizontal_find_first
__attribute__((noinline))
#endif
static uint32_t bit_scan_forward(uint32_t a) {
uint32_t r;
__asm("bsfl %1, %0" : "=r"(r) : "r"(a) : );
return r;
}
static inline uint32_t bit_scan_forward(uint64_t a) {
uint32_t lo = uint32_t(a);
if (lo) return bit_scan_forward(lo);
uint32_t hi = uint32_t(a >> 32);
return bit_scan_forward(hi) + 32;
}
#else // MS compatible compilers under Windows
static inline uint32_t bit_scan_forward(uint32_t a) {
unsigned long r;
_BitScanForward(&r, a); // defined in intrin.h for MS and Intel compilers
return r;
}
#ifdef __x86_64__
static inline uint32_t bit_scan_forward(uint64_t a) {
unsigned long r;
_BitScanForward64(&r, a); // defined in intrin.h for MS and Intel compilers
return (uint32_t)r;
}
#else
static inline uint32_t bit_scan_forward(uint64_t a) {
uint32_t lo = uint32_t(a);
if (lo) return bit_scan_forward(lo);
uint32_t hi = uint32_t(a >> 32);
return bit_scan_forward(hi) + 32;
}
#endif
#endif
// Define bit-scan-reverse function. Gives index to highest set bit = floor(log2(a))
#if (defined (__GNUC__) || defined(__clang__)) && !defined (_MSC_VER)
// _BitScanReverse intrinsics are defined only under Windows and only when _MSC_VER is defined
// Use inline assembly for gcc and Clang
static inline uint32_t bit_scan_reverse(uint32_t a) __attribute__((pure));
static inline uint32_t bit_scan_reverse(uint32_t a) {
uint32_t r;
__asm("bsrl %1, %0" : "=r"(r) : "r"(a) : );
return r;
}
#ifdef __x86_64__
static inline uint32_t bit_scan_reverse(uint64_t a) {
uint64_t r;
__asm("bsrq %1, %0" : "=r"(r) : "r"(a) : );
return uint32_t(r);
}
#else // 32 bit mode
static inline uint32_t bit_scan_reverse(uint64_t a) {
uint64_t ahi = a >> 32;
if (ahi == 0) return bit_scan_reverse(uint32_t(a));
else return bit_scan_reverse(uint32_t(ahi)) + 32;
}
#endif
#else // MS compatible compilers under Windows
static inline uint32_t bit_scan_reverse(uint32_t a) {
unsigned long r;
_BitScanReverse(&r, a); // defined in intrin.h for MS compatible compilers
return r;
}
#ifdef __x86_64__
static inline uint32_t bit_scan_reverse(uint64_t a) {
unsigned long r;
_BitScanReverse64(&r, a); // defined in intrin.h for MS compatible compilers
return r;
}
#else // 32 bit mode
static inline uint32_t bit_scan_reverse(uint64_t a) {
uint64_t ahi = a >> 32;
if (ahi == 0) return bit_scan_reverse(uint32_t(a));
else return bit_scan_reverse(uint32_t(ahi)) + 32;
}
#endif
#endif
// Same function, for compile-time constants
constexpr int bit_scan_reverse_const(uint64_t const n) {
if (n == 0) return -1;
uint64_t a = n, b = 0, j = 64, k = 0;
do {
j >>= 1;
k = (uint64_t)1 << j;
if (a >= k) {
a >>= j;
b += j;
}
} while (j > 0);
return int(b);
}
/*****************************************************************************
*
* Common templates
*
*****************************************************************************/
#ifdef VCL_NAMESPACE
#define NAMESPACEPREFIX VCL_NAMESPACE::
#else
#define NAMESPACEPREFIX
#endif
template <int32_t n> class Const_int_t {}; // represent compile-time signed integer constant
template <uint32_t n> class Const_uint_t {}; // represent compile-time unsigned integer constant
#define const_int(n) (NAMESPACEPREFIX Const_int_t <n>()) // n must be compile-time integer constant
#define const_uint(n) (NAMESPACEPREFIX Const_uint_t<n>()) // n must be compile-time unsigned integer constant
// template for producing quiet NAN
template <class VTYPE>
static inline VTYPE nan_vec(uint32_t payload = 0x100) {
if constexpr (VTYPE::elementtype() == 17) { // double
union {
uint64_t q;
double f;
} ud;
// n is left justified to avoid loss of NAN payload when converting to float
ud.q = 0x7FF8000000000000 | uint64_t(payload) << 29;
return VTYPE(ud.f);
}
if constexpr (VTYPE::elementtype() == 16) { // float
union {
uint32_t i;
float f;
} uf;
uf.i = 0x7FC00000 | (payload & 0x003FFFFF);
return VTYPE(uf.f);
}
/* // defined in vectorfp16.h
if constexpr (VTYPE::elementtype() == 15) { // _Float16
union {
uint16_t i;
_Float16 f; // error if _Float16 not defined
} uf;
uf.i = 0x7C00 | (payload & 0x03FF);
return VTYPE(uf.f);
} */
}
// Test if a parameter is a compile-time constant
/* Unfortunately, this works only for macro parameters, not for inline function parameters.
I hope that some solution will appear in the future, but for now it appears to be
impossible to check if a function parameter is a compile-time constant.
This would be useful in operator / and in function pow:
#if defined(__GNUC__) || defined (__clang__)
#define is_constant(a) __builtin_constant_p(a)
#else
#define is_constant(a) false
#endif
*/
/*****************************************************************************
*
* Helper functions for permute and blend functions
*
******************************************************************************
Rules for constexpr functions:
> All variable declarations must include initialization
> Do not put variable declarations inside a for-clause, e.g. avoid: for (int i=0; ..
Instead, you have to declare the loop counter before the for-loop.
> Do not make constexpr functions that return vector types. This requires type
punning with a union, which is not allowed in constexpr functions under C++17.
*****************************************************************************/
// Define type for encapsulated array to use as return type:
template <typename T, int N>
struct EList {
T a[N];
};
// get_inttype: get an integer of a size that matches the element size
// of vector class V with the value -1
template <typename V>
constexpr auto get_inttype() {
constexpr int elementsize = int(sizeof(V) / V::size()); // size of vector elements
if constexpr (elementsize >= 8) {
return -int64_t(1);
}
else if constexpr (elementsize >= 4) {
return int32_t(-1);
}
else if constexpr (elementsize >= 2) {
return int16_t(-1);
}
else {
return int8_t(-1);
}
}
// zero_mask: return a compact bit mask mask for zeroing using AVX512 mask.
// Parameter a is a reference to a constexpr int array of permutation indexes
template <int N>
constexpr auto zero_mask(int const (&a)[N]) {
uint64_t mask = 0;
int i = 0;
for (i = 0; i < N; i++) {
if (a[i] >= 0) mask |= uint64_t(1) << i;
}
if constexpr (N <= 8 ) return uint8_t(mask);
else if constexpr (N <= 16) return uint16_t(mask);
else if constexpr (N <= 32) return uint32_t(mask);
else return mask;
}
// zero_mask_broad: return a broad byte mask for zeroing.
// Parameter a is a reference to a constexpr int array of permutation indexes
template <typename V>
constexpr auto zero_mask_broad(int const (&A)[V::size()]) {
constexpr int N = V::size(); // number of vector elements
typedef decltype(get_inttype<V>()) Etype; // element type
EList <Etype, N> u = {{0}}; // list for return
int i = 0;
for (i = 0; i < N; i++) {
u.a[i] = A[i] >= 0 ? get_inttype<V>() : 0;
}
return u; // return encapsulated array
}
// make_bit_mask: return a compact mask of bits from a list of N indexes:
// B contains options indicating how to gather the mask
// bit 0-7 in B indicates which bit in each index to collect
// bit 8 = 0x100: set 1 in the lower half of the bit mask if the indicated bit is 1.
// bit 8 = 0 : set 1 in the lower half of the bit mask if the indicated bit is 0.
// bit 9 = 0x200: set 1 in the upper half of the bit mask if the indicated bit is 1.
// bit 9 = 0 : set 1 in the upper half of the bit mask if the indicated bit is 0.
// bit 10 = 0x400: set 1 in the bit mask if the corresponding index is -1 or V_DC
// Parameter a is a reference to a constexpr int array of permutation indexes
template <int N, int B>
constexpr uint64_t make_bit_mask(int const (&a)[N]) {
uint64_t r = 0; // return value
uint8_t j = uint8_t(B & 0xFF); // index to selected bit
uint64_t s = 0; // bit number i in r
uint64_t f = 0; // 1 if bit not flipped
int i = 0;
for (i = 0; i < N; i++) {
int ix = a[i];
if (ix < 0) { // -1 or V_DC
s = (B >> 10) & 1;
}
else {
s = ((uint32_t)ix >> j) & 1; // extract selected bit
if (i < N/2) {
f = (B >> 8) & 1; // lower half
}
else {
f = (B >> 9) & 1; // upper half
}
s ^= f ^ 1; // flip bit if needed
}
r |= uint64_t(s) << i; // set bit in return value
}
return r;
}
// make_broad_mask: Convert a bit mask m to a broad mask
// The return value will be a broad boolean mask with elementsize matching vector class V
template <typename V>
constexpr auto make_broad_mask(uint64_t const m) {
constexpr int N = V::size(); // number of vector elements
typedef decltype(get_inttype<V>()) Etype; // element type
EList <Etype, N> u = {{0}}; // list for returning
int i = 0;
for (i = 0; i < N; i++) {
u.a[i] = ((m >> i) & 1) != 0 ? get_inttype<V>() : 0;
}
return u; // return encapsulated array
}
// perm_mask_broad: return a mask for permutation by a vector register index.
// Parameter A is a reference to a constexpr int array of permutation indexes
template <typename V>
constexpr auto perm_mask_broad(int const (&A)[V::size()]) {
constexpr int N = V::size(); // number of vector elements
typedef decltype(get_inttype<V>()) Etype; // vector element type
EList <Etype, N> u = {{0}}; // list for returning
int i = 0;
for (i = 0; i < N; i++) {
u.a[i] = Etype(A[i]);
}
return u; // return encapsulated array
}
// perm_flags: returns information about how a permute can be implemented.
// The return value is composed of these flag bits:
const int perm_zeroing = 1; // needs zeroing
const int perm_perm = 2; // permutation needed
const int perm_allzero = 4; // all is zero or don't care
const int perm_largeblock = 8; // fits permute with a larger block size (e.g permute Vec2q instead of Vec4i)
const int perm_addz = 0x10; // additional zeroing needed after permute with larger block size or shift
const int perm_addz2 = 0x20; // additional zeroing needed after perm_zext, perm_compress, or perm_expand
const int perm_cross_lane = 0x40; // permutation crossing 128-bit lanes
const int perm_same_pattern = 0x80; // same permute pattern in all 128-bit lanes
const int perm_punpckh = 0x100; // permutation pattern fits punpckh instruction
const int perm_punpckl = 0x200; // permutation pattern fits punpckl instruction
const int perm_rotate = 0x400; // permutation pattern fits 128-bit rotation within lanes. 4 bit byte count returned in bit perm_rot_count
const int perm_swap = 0x800; // permutation pattern fits swap of adjacent vector elements
const int perm_shright = 0x1000; // permutation pattern fits shift right within lanes. 4 bit count returned in bit perm_rot_count
const int perm_shleft = 0x2000; // permutation pattern fits shift left within lanes. negative count returned in bit perm_rot_count
const int perm_rotate_big = 0x4000; // permutation pattern fits rotation across lanes. 6 bit count returned in bit perm_rot_count
const int perm_broadcast = 0x8000; // permutation pattern fits broadcast of a single element.
const int perm_zext = 0x10000; // permutation pattern fits zero extension
const int perm_compress = 0x20000; // permutation pattern fits vpcompress instruction
const int perm_expand = 0x40000; // permutation pattern fits vpexpand instruction
const int perm_outofrange = 0x10000000; // index out of range
const int perm_rot_count = 32; // rotate or shift count is in bits perm_rot_count to perm_rot_count+3
const int perm_ipattern = 40; // pattern for pshufd is in bit perm_ipattern to perm_ipattern + 7 if perm_same_pattern and elementsize >= 4
template <typename V>
constexpr uint64_t perm_flags(int const (&a)[V::size()]) {
// a is a reference to a constexpr array of permutation indexes
// V is a vector class
constexpr int N = V::size(); // number of elements
uint64_t r = perm_largeblock | perm_same_pattern | perm_allzero; // return value
uint32_t i = 0; // loop counter
int j = 0; // loop counter
int ix = 0; // index number i
const uint32_t nlanes = sizeof(V) / 16; // number of 128-bit lanes
const uint32_t lanesize = N / nlanes; // elements per lane
const uint32_t elementsize = sizeof(V) / N; // size of each vector element
uint32_t lane = 0; // current lane
uint32_t rot = 999; // rotate left count
int32_t broadc = 999; // index to broadcasted element
uint32_t patfail = 0; // remember certain patterns that do not fit
uint32_t addz2 = 0; // remember certain patterns need extra zeroing
int32_t compresslasti = -1; // last index in perm_compress fit
int32_t compresslastp = -1; // last position in perm_compress fit
int32_t expandlasti = -1; // last index in perm_expand fit
int32_t expandlastp = -1; // last position in perm_expand fit
int lanepattern[lanesize] = {0}; // pattern in each lane
for (i = 0; i < N; i++) { // loop through indexes
ix = a[i]; // current index
// meaning of ix: -1 = set to zero, V_DC = don't care, non-negative value = permute.
if (ix == -1) {
r |= perm_zeroing; // zeroing requested
}
else if (ix != V_DC && uint32_t(ix) >= N) {
r |= perm_outofrange; // index out of range
}
if (ix >= 0) {
r &= ~ perm_allzero; // not all zero
if (ix != (int)i) r |= perm_perm; // needs permutation
if (broadc == 999) broadc = ix; // remember broadcast index
else if (broadc != ix) broadc = 1000; // does not fit broadcast
}
// check if pattern fits a larger block size:
// even indexes must be even, odd indexes must fit the preceding even index + 1
if ((i & 1) == 0) { // even index
if (ix >= 0 && (ix & 1)) r &= ~perm_largeblock;// not even. does not fit larger block size
int iy = a[i + 1]; // next odd index
if (iy >= 0 && (iy & 1) == 0) r &= ~ perm_largeblock; // not odd. does not fit larger block size
if (ix >= 0 && iy >= 0 && iy != ix+1) r &= ~ perm_largeblock; // does not fit preceding index + 1
if (ix == -1 && iy >= 0) r |= perm_addz; // needs additional zeroing at current block size
if (iy == -1 && ix >= 0) r |= perm_addz; // needs additional zeroing at current block size
}
lane = i / lanesize; // current lane
if (lane == 0) { // first lane, or no pattern yet
lanepattern[i] = ix; // save pattern
}
// check if crossing lanes
if (ix >= 0) {
uint32_t lanei = (uint32_t)ix / lanesize; // source lane
if (lanei != lane) r |= perm_cross_lane; // crossing lane
}
// check if same pattern in all lanes
if (lane != 0 && ix >= 0) { // not first lane
int j1 = int(i - int(lane * lanesize)); // index into lanepattern
int jx = int(ix - int(lane * lanesize)); // pattern within lane
if (jx < 0 || jx >= (int)lanesize) r &= ~perm_same_pattern; // source is in another lane
if (lanepattern[j1] < 0) {
lanepattern[j1] = jx; // pattern not known from previous lane
}
else {
if (lanepattern[j1] != jx) r &= ~perm_same_pattern; // not same pattern
}
}
if (ix >= 0) {
// check if pattern fits zero extension (perm_zext)
if (uint32_t(ix*2) != i) {
patfail |= 1; // does not fit zero extension
}
// check if pattern fits compress (perm_compress)
if (ix > compresslasti && ix - compresslasti >= (int)i - compresslastp) {
if ((int)i - compresslastp > 1) addz2 |= 2;// perm_compress may need additional zeroing
compresslasti = ix; compresslastp = int(i);
}
else {
patfail |= 2; // does not fit perm_compress
}
// check if pattern fits expand (perm_expand)
if (ix > expandlasti && ix - expandlasti <= (int)i - expandlastp) {
if (ix - expandlasti > 1) addz2 |= 4; // perm_expand may need additional zeroing
expandlasti = ix; expandlastp = int(i);
}
else {
patfail |= 4; // does not fit perm_compress
}
}
else if (ix == -1) {
if ((i & 1) == 0) addz2 |= 1; // zero extension needs additional zeroing
}
}
if (!(r & perm_perm)) return r; // more checks are superfluous
if (!(r & perm_largeblock)) r &= ~ perm_addz; // remove irrelevant flag
if (r & perm_cross_lane) r &= ~ perm_same_pattern; // remove irrelevant flag
if ((patfail & 1) == 0) {
r |= perm_zext; // fits zero extension
if ((addz2 & 1) != 0) r |= perm_addz2;
}
else if ((patfail & 2) == 0) {
r |= perm_compress; // fits compression
if ((addz2 & 2) != 0) { // check if additional zeroing needed
for (j = 0; j < compresslastp; j++) {
if (a[j] == -1) r |= perm_addz2;
}
}
}
else if ((patfail & 4) == 0) {
r |= perm_expand; // fits expansion
if ((addz2 & 4) != 0) { // check if additional zeroing needed
for (j = 0; j < expandlastp; j++) {
if (a[j] == -1) r |= perm_addz2;
}
}
}
if (r & perm_same_pattern) {
// same pattern in all lanes. check if it fits specific patterns
bool fit = true; // fits perm_rotate
bool fitswap = true; // fits perm_swap
// fit shift or rotate
for (i = 0; i < lanesize; i++) {
if (lanepattern[i] >= 0) {
uint32_t rot1 = uint32_t(lanepattern[i] + lanesize - i) % lanesize;
if (rot == 999) {
rot = rot1;
}
else { // check if fit
if (rot != rot1) fit = false;
}
if ((uint32_t)lanepattern[i] != (i ^ 1)) fitswap = false;
}
}
rot &= lanesize-1; // prevent out of range values
if (fitswap) r |= perm_swap;
if (fit) { // fits rotate, and possibly shift
uint64_t rot2 = (rot * elementsize) & 0xF; // rotate right count in bytes
r |= rot2 << perm_rot_count; // put shift/rotate count in output bit 16-19
#if INSTRSET >= 4 // SSSE3
r |= perm_rotate; // allow palignr
#endif
// fit shift left
fit = true;
for (i = 0; i < lanesize-rot; i++) { // check if first rot elements are zero or don't care
if (lanepattern[i] >= 0) fit = false;
}
if (fit) {
r |= perm_shleft;
for (; i < lanesize; i++) if (lanepattern[i] == -1) r |= perm_addz; // additional zeroing needed
}
// fit shift right
fit = true;
for (i = lanesize-(uint32_t)rot; i < lanesize; i++) { // check if last (lanesize-rot) elements are zero or don't care
if (lanepattern[i] >= 0) fit = false;
}
if (fit) {
r |= perm_shright;
for (i = 0; i < lanesize-rot; i++) {
if (lanepattern[i] == -1) r |= perm_addz; // additional zeroing needed
}
}
}
// fit punpckhi
fit = true;
uint32_t j2 = lanesize / 2;
for (i = 0; i < lanesize; i++) {
if (lanepattern[i] >= 0 && lanepattern[i] != (int)j2) fit = false;
if ((i & 1) != 0) j2++;
}
if (fit) r |= perm_punpckh;
// fit punpcklo
fit = true;
j2 = 0;
for (i = 0; i < lanesize; i++) {
if (lanepattern[i] >= 0 && lanepattern[i] != (int)j2) fit = false;
if ((i & 1) != 0) j2++;
}
if (fit) r |= perm_punpckl;
// fit pshufd
if constexpr (elementsize >= 4) {
uint32_t p = 0;
for (i = 0; i < lanesize; i++) {
if constexpr (lanesize == 4) {
p |= (lanepattern[i] & 3) << 2 * i;
}
else { // lanesize = 2
p |= ((lanepattern[i] & 1) * 10 + 4) << 4 * i;
}
}
r |= (uint64_t)p << perm_ipattern;
}
}
#if INSTRSET >= 7
else { // not same pattern in all lanes
if constexpr (nlanes > 1) { // Try if it fits big rotate
for (i = 0; i < N; i++) {
ix = a[i];
if (ix >= 0) {
uint32_t rot2 = (ix + N - i) % N; // rotate count
if (rot == 999) {
rot = rot2; // save rotate count
}
else if (rot != rot2) {
rot = 1000; break; // does not fit big rotate
}
}
}
if (rot < N) { // fits big rotate
r |= perm_rotate_big | (uint64_t)rot << perm_rot_count;
}
}
}
#endif
if (broadc < 999 && (r & (perm_rotate|perm_shright|perm_shleft|perm_rotate_big)) == 0) {
r |= perm_broadcast | (uint64_t)broadc << perm_rot_count; // fits broadcast
}
return r;
}
// compress_mask: returns a bit mask to use for compression instruction.
// It is presupposed that perm_flags indicates perm_compress.
// Additional zeroing is needed if perm_flags indicates perm_addz2
template <int N>
constexpr uint64_t compress_mask(int const (&a)[N]) {
// a is a reference to a constexpr array of permutation indexes
int ix = 0, lasti = -1, lastp = -1;
uint64_t m = 0;
int i = 0; int j = 1; // loop counters
for (i = 0; i < N; i++) {
ix = a[i]; // permutation index
if (ix >= 0) {
m |= (uint64_t)1 << ix; // mask for compression source
for (j = 1; j < i - lastp; j++) {
m |= (uint64_t)1 << (lasti + j); // dummy filling source
}
lastp = i; lasti = ix;
}
}
return m;
}
// expand_mask: returns a bit mask to use for expansion instruction.
// It is presupposed that perm_flags indicates perm_expand.
// Additional zeroing is needed if perm_flags indicates perm_addz2
template <int N>
constexpr uint64_t expand_mask(int const (&a)[N]) {
// a is a reference to a constexpr array of permutation indexes
int ix = 0, lasti = -1, lastp = -1;
uint64_t m = 0;
int i = 0; int j = 1;
for (i = 0; i < N; i++) {
ix = a[i]; // permutation index
if (ix >= 0) {
m |= (uint64_t)1 << i; // mask for expansion destination
for (j = 1; j < ix - lasti; j++) {
m |= (uint64_t)1 << (lastp + j); // dummy filling destination
}
lastp = i; lasti = ix;
}
}
return m;
}
// perm16_flags: returns information about how to permute a vector of 16-bit integers
// Note: It is presupposed that perm_flags reports perm_same_pattern
// The return value is composed of these bits:
// 1: data from low 64 bits to low 64 bits. pattern in bit 32-39
// 2: data from high 64 bits to high 64 bits. pattern in bit 40-47
// 4: data from high 64 bits to low 64 bits. pattern in bit 48-55
// 8: data from low 64 bits to high 64 bits. pattern in bit 56-63
template <typename V>
constexpr uint64_t perm16_flags(int const (&a)[V::size()]) {
// a is a reference to a constexpr array of permutation indexes
// V is a vector class
constexpr int N = V::size(); // number of elements
uint64_t retval = 0; // return value
uint32_t pat[4] = {0,0,0,0}; // permute patterns
uint32_t i = 0; // loop counter
int ix = 0; // index number i
const uint32_t lanesize = 8; // elements per lane
uint32_t lane = 0; // current lane
int lanepattern[lanesize] = {0}; // pattern in each lane
for (i = 0; i < N; i++) {
ix = a[i];
lane = i / lanesize; // current lane
if (lane == 0) {
lanepattern[i] = ix; // save pattern
}
else if (ix >= 0) { // not first lane
uint32_t j = i - lane * lanesize; // index into lanepattern
int jx = int(ix - lane * lanesize); // pattern within lane
if (lanepattern[j] < 0) {
lanepattern[j] = jx; // pattern not known from previous lane
}
}
}
// four patterns: low2low, high2high, high2low, low2high
for (i = 0; i < 4; i++) {
// loop through low pattern
if (lanepattern[i] >= 0) {
if (lanepattern[i] < 4) { // low2low
retval |= 1;
pat[0] |= uint32_t(lanepattern[i] & 3) << (2 * i);
}
else { // high2low
retval |= 4;
pat[2] |= uint32_t(lanepattern[i] & 3) << (2 * i);
}
}
// loop through high pattern
if (lanepattern[i+4] >= 0) {
if (lanepattern[i+4] < 4) { // low2high
retval |= 8;
pat[3] |= uint32_t(lanepattern[i+4] & 3) << (2 * i);
}
else { // high2high
retval |= 2;
pat[1] |= uint32_t(lanepattern[i+4] & 3) << (2 * i);
}
}
}
// join return data
for (i = 0; i < 4; i++) {
retval |= (uint64_t)pat[i] << (32 + i*8);
}
return retval;
}
// pshufb_mask: return a broad byte mask for permutation within lanes
// for use with the pshufb instruction (_mm..._shuffle_epi8).
// The pshufb instruction provides fast permutation and zeroing,
// allowing different patterns in each lane but no crossing of lane boundaries
template <typename V, int oppos = 0>
constexpr auto pshufb_mask(int const (&A)[V::size()]) {
// Parameter a is a reference to a constexpr array of permutation indexes
// V is a vector class
// oppos = 1 for data from the opposite 128-bit lane in 256-bit vectors
constexpr uint32_t N = uint32_t(V::size()); // number of vector elements
constexpr uint32_t elementsize = sizeof(V) / N; // size of each vector element
constexpr uint32_t nlanes = sizeof(V) / 16; // number of 128 bit lanes in vector
constexpr uint32_t elements_per_lane = N / nlanes; // number of vector elements per lane
EList <int8_t, sizeof(V)> u = {{0}}; // list for returning
uint32_t i = 0; // loop counters
uint32_t j = 0;
int m = 0;
int k = 0;
uint32_t lane = 0;
for (lane = 0; lane < nlanes; lane++) { // loop through lanes
for (i = 0; i < elements_per_lane; i++) { // loop through elements in lane
// permutation index for element within lane
int8_t p = -1;
int ix = A[m];
if (ix >= 0) {
ix ^= oppos * elements_per_lane; // flip bit if opposite lane
}
ix -= int(lane * elements_per_lane); // index relative to lane
if (ix >= 0 && ix < (int)elements_per_lane) { // index points to desired lane
p = int8_t(ix * elementsize);
}
for (j = 0; j < elementsize; j++) { // loop through bytes in element
u.a[k++] = int8_t(p < 0 ? -1 : p + j); // store byte permutation index
}
m++;
}
}
return u; // return encapsulated array
}
// largeblock_perm: return indexes for replacing a permute or blend with
// a certain block size by a permute or blend with the double block size.
// Note: it is presupposed that perm_flags() indicates perm_largeblock
// It is required that additional zeroing is added if perm_flags() indicates perm_addz
template <int N>
constexpr EList<int, N/2> largeblock_perm(int const (&a)[N]) {
// Parameter a is a reference to a constexpr array of permutation indexes
EList<int, N/2> list = {{0}}; // result indexes