Enable MM_PREFETCH and MM_MALLOC on aarch64

[StrikerRUS]

Refer to #3948 (comment).

Related source codes:

LightGBM/CMakeLists.txt

Lines 243 to 271 in e98da99

	include(CheckCXXSourceCompiles)
	check_cxx_source_compiles("
	#include <xmmintrin.h>
	int main() {
	int a = 0;
	_mm_prefetch(&a, _MM_HINT_NTA);
	return 0;
	}
	" MM_PREFETCH)
	if(${MM_PREFETCH})
	message(STATUS "Using _mm_prefetch")
	ADD_DEFINITIONS(-DMM_PREFETCH)
	endif()
	include(CheckCXXSourceCompiles)
	check_cxx_source_compiles("
	#include <mm_malloc.h>
	int main() {
	char *a = (char*)_mm_malloc(8, 16);
	_mm_free(a);
	return 0;
	}
	" MM_MALLOC)
	if(${MM_MALLOC})
	message(STATUS "Using _mm_malloc")
	ADD_DEFINITIONS(-DMM_MALLOC)
	endif()

LightGBM/include/LightGBM/meta.h

Lines 16 to 23 in e98da99

	#if (defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64))) || defined(__INTEL_COMPILER) || MM_PREFETCH
	#include <xmmintrin.h>
	#define PREFETCH_T0(addr) _mm_prefetch(reinterpret_cast<const char*>(addr), _MM_HINT_T0)
	#elif defined(__GNUC__)
	#define PREFETCH_T0(addr) __builtin_prefetch(reinterpret_cast<const char*>(addr), 0, 3)
	#else
	#define PREFETCH_T0(addr) do {} while (0)
	#endif

LightGBM/include/LightGBM/utils/common.h

Lines 44 to 58 in e98da99

	#if defined(_MSC_VER)
	#include <malloc.h>
	#elif MM_MALLOC
	#include <mm_malloc.h>
	// https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html
	// https://www.oreilly.com/library/view/mac-os-x/0596003560/ch05s01s02.html
	#elif defined(__GNUC__) && defined(HAVE_MALLOC_H)
	#include <malloc.h>
	#define _mm_malloc(a, b) memalign(b, a)
	#define _mm_free(a) free(a)
	#else
	#include <stdlib.h>
	#define _mm_malloc(a, b) malloc(a)
	#define _mm_free(a) free(a)
	#endif

[StrikerRUS]

Closed in favor of being in #2302. We decided to keep all feature requests in one place.

Welcome to contribute this feature! Please re-open this issue (or post a comment if you are not a topic starter) if you are actively working on implementing this feature.

[jameslamb]

See the error at https://clang.llvm.org/doxygen/xmmintrin_8h_source.html.

error: "This header is only meant to be used on x86 and x64 architecture"

This can be reproduced like this:

// conftest.cpp
#include <xmmintrin.h>

void main() {
    int a = 0;
    _mm_prefetch(&a, _MM_HINT_NTA);
    return 0;
}

clang++ -arch arm64 -std=gnu++17 -o conftest conftest.cpp

[StrikerRUS]

I'm not an expert in all these things at all, but it looks like Arm Compiler supports prefetching via __builtin_prefetch.
https://developer.arm.com/documentation/101458/2404/Optimize/Prefetching-with---builtin-prefetch?lang=en

UPD: ... and gcc: https://github.com/gcc-mirror/gcc/blob/master/gcc/testsuite/gcc.target/aarch64/vect-prefetch-drop.c

[StrikerRUS]

Linking #4331 and #6514 (comment).