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"

#if (CRYPTOPP_ARM_NEON_AVAILABLE)
# include <arm_neon.h>
#endif

// Can't use CRYPTOPP_ARM_XXX_AVAILABLE because too many
// compilers don't follow ACLE conventions for the include.
#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(__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
    {
        // Modern MS hardware is ARMv7
        result = true;
    }
    __except (EXCEPTION_EXECUTE_HANDLER)
    {
        return false;
    }
    return result;
# elif defined(__arm__) && (__ARM_ARCH >= 7)
    // 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
    {
        // ARMv7 added movt and movw
        int a;
        asm volatile("movw %0,%1 \n"
                     "movt %0,%1 \n"
                     : "=r"(a) : "i"(0x1234));
        result = (a == 0x12341234);
    }

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

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