ext-cryptopp/neon_simd.cpp

// crc_simd.cpp - written and placed in the public domain by
//                Jeffrey Walton, Uri Blumenthal and Marcel Raad.
//
//    This source file uses intrinsics to gain access to ARMv7a and
//    ARMv8a NEON instructions. A separate source file is needed
//    because additional CXXFLAGS are required to enable the
//    appropriate instructions sets in some build configurations.

#include "pch.h"
#include "config.h"
#include "stdcpp.h"

// C1189: error: This header is specific to ARM targets
#if (CRYPTOPP_ARM_NEON_AVAILABLE) && !defined(_M_ARM64)
# include <arm_neon.h>
#endif

#if (CRYPTOPP_ARM_ACLE_AVAILABLE)
# include <stdint.h>
# include <arm_acle.h>
#endif

#ifdef CRYPTOPP_GNU_STYLE_INLINE_ASSEMBLY
# include <signal.h>
# include <setjmp.h>
#endif

#ifndef EXCEPTION_EXECUTE_HANDLER
# define EXCEPTION_EXECUTE_HANDLER 1
#endif

// Squash MS LNK4221 and libtool warnings
extern const char NEON_SIMD_FNAME[] = __FILE__;

NAMESPACE_BEGIN(CryptoPP)

#ifdef CRYPTOPP_GNU_STYLE_INLINE_ASSEMBLY
extern "C" {
    typedef void (*SigHandler)(int);

	static jmp_buf s_jmpSIGILL;
	static void SigIllHandler(int)
	{
		longjmp(s_jmpSIGILL, 1);
	}
}
#endif  // Not CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY

bool CPU_ProbeARMv7()
{
#if defined(CRYPTOPP_NO_CPU_FEATURE_PROBES)
	return false;
#elif CRYPTOPP_BOOL_ARM32
# if defined(CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY)
	volatile bool result = true;
	__try
	{
		// Modern MS hardware is ARMv7
		result = true;
	}
	__except (EXCEPTION_EXECUTE_HANDLER)
	{
		return false;
	}
	return result;
# elif defined(__GNUC__) || defined(__clang__)
	// longjmp and clobber warnings. Volatile is required.
	// http://github.com/weidai11/cryptopp/issues/24 and http://stackoverflow.com/q/7721854
	volatile bool result = true;

	volatile SigHandler oldHandler = signal(SIGILL, SigIllHandler);
	if (oldHandler == SIG_ERR)
		return false;

	volatile sigset_t oldMask;
	if (sigprocmask(0, NULLPTR, (sigset_t*)&oldMask))
		return false;

	if (setjmp(s_jmpSIGILL))
		result = false;
	else
	{

#if 0
		// ARMv7 added movt and movw
		int a;
		asm volatile("movw %0,%1 \n"
		             "movt %0,%1 \n"
		             : "=r"(a) : "i"(0x1234));

00000010 <_Z5test2v>:  // ARM
  10:   e3010234        movw    r0, #4660       ; 0x1234
  14:   e3410234        movt    r0, #4660       ; 0x1234
  18:   e12fff1e        bx      lr

0000001c <_Z5test3v>:  // Thumb
  1c:   f241 2034       movw    r0, #4660       ; 0x1234
  20:   f2c1 2034       movt    r0, #4660       ; 0x1234
  24:   e12fff1e        bx      lr
#endif

		int a;
		asm volatile (
		    ".arm              \n\t"
		    ".inst 0xe3010234  \n\t"   // movw r0, 0x1234
		    ".inst 0xe3410234  \n\t"   // movt r0, 0x1234
		    "mov %0, r0        \n\t"   // mov [a], r0
		    : "=r" (a) : : "r0");

		result = (a == 0x12341234);
	}

	sigprocmask(SIG_SETMASK, (sigset_t*)&oldMask, NULLPTR);
	signal(SIGILL, oldHandler);
	return result;
# endif
#else
	return false;
#endif  // CRYPTOPP_BOOL_ARM32
}

bool CPU_ProbeNEON()
{
#if defined(__aarch32__) || defined(__aarch64__)
	return true;
#elif defined(CRYPTOPP_NO_CPU_FEATURE_PROBES)
	return false;
#elif (CRYPTOPP_ARM_NEON_AVAILABLE)
# if defined(CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY)
	volatile bool result = true;
	__try
	{
		uint32_t v1[4] = {1,1,1,1};
		uint32x4_t x1 = vld1q_u32(v1);
		uint64_t v2[2] = {1,1};
		uint64x2_t x2 = vld1q_u64(v2);

		uint32x4_t x3 = vdupq_n_u32(2);
		x3 = vsetq_lane_u32(vgetq_lane_u32(x1,0),x3,0);
		x3 = vsetq_lane_u32(vgetq_lane_u32(x1,3),x3,3);
		uint64x2_t x4 = vdupq_n_u64(2);
		x4 = vsetq_lane_u64(vgetq_lane_u64(x2,0),x4,0);
		x4 = vsetq_lane_u64(vgetq_lane_u64(x2,1),x4,1);

		result = !!(vgetq_lane_u32(x3,0) | vgetq_lane_u64(x4,1));
	}
	__except (EXCEPTION_EXECUTE_HANDLER)
	{
		return false;
	}
	return result;
# else

	// longjmp and clobber warnings. Volatile is required.
	// http://github.com/weidai11/cryptopp/issues/24 and http://stackoverflow.com/q/7721854
	volatile bool result = true;

	volatile SigHandler oldHandler = signal(SIGILL, SigIllHandler);
	if (oldHandler == SIG_ERR)
		return false;

	volatile sigset_t oldMask;
	if (sigprocmask(0, NULLPTR, (sigset_t*)&oldMask))
		return false;

	if (setjmp(s_jmpSIGILL))
		result = false;
	else
	{
		uint32_t v1[4] = {1,1,1,1};
		uint32x4_t x1 = vld1q_u32(v1);
		uint64_t v2[2] = {1,1};
		uint64x2_t x2 = vld1q_u64(v2);

		uint32x4_t x3 = {0,0,0,0};
		x3 = vsetq_lane_u32(vgetq_lane_u32(x1,0),x3,0);
		x3 = vsetq_lane_u32(vgetq_lane_u32(x1,3),x3,3);
		uint64x2_t x4 = {0,0};
		x4 = vsetq_lane_u64(vgetq_lane_u64(x2,0),x4,0);
		x4 = vsetq_lane_u64(vgetq_lane_u64(x2,1),x4,1);

		// Hack... GCC optimizes away the code and returns true
		result = !!(vgetq_lane_u32(x3,0) | vgetq_lane_u64(x4,1));
	}

	sigprocmask(SIG_SETMASK, (sigset_t*)&oldMask, NULLPTR);
	signal(SIGILL, oldHandler);
	return result;
# endif
#else
	return false;
#endif  // CRYPTOPP_ARM_NEON_AVAILABLE
}

NAMESPACE_END