celt_arm_asm.h - mozsearch

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/* Copyright (c) 2026 Lynne */

/*

   Redistribution and use in source and binary forms, with or without

   modification, are permitted provided that the following conditions

   are met:

   - Redistributions of source code must retain the above copyright

   notice, this list of conditions and the following disclaimer.

   - Redistributions in binary form must reproduce the above copyright

   notice, this list of conditions and the following disclaimer in the

   documentation and/or other materials provided with the distribution.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER

   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

/*

 * Shared AArch64 GAS macros for libopus NEON assembly, #included into the

 * .S files (the C preprocessor runs on .S, so __APPLE__/__ELF__ are visible).

 * A minimal subset of FFmpeg's libavutil/aarch64/asm.S covering both ELF

 * (Linux/Android) and Mach-O (Apple): function/endfunc/const/endconst/movrel,

 * leading-underscore symbol prefixing on Apple, hidden visibility, and the

 * BTI/PAC branch protection hooks. Windows omitted.

*/

#ifndef CELT_ARM_ASM_H

#define CELT_ARM_ASM_H

#ifndef __APPLE__

        .arch   armv8-a

#endif

/* EXTERN_ASM is the C-symbol prefix: a leading underscore on Apple, nothing

   on ELF. X(sym) applies it, for referencing exported symbols (bl X(name)). */

#if defined(__APPLE__)

#  define EXTERN_ASM _

#else

#  define EXTERN_ASM

#endif

#define OPUS_GLUE(a, b) a ## b

#define OPUS_JOIN(a, b) OPUS_GLUE(a, b)

#define X(s) OPUS_JOIN(EXTERN_ASM, s)

/* Branch protection, as in FFmpeg's asm.S: with -mbranch-protection=standard

   the compiler defines __ARM_FEATURE_{BTI,PAC}_DEFAULT for .S files too.

   Exported functions get a BTI 'c' landing pad (all are called through

   function pointers), LR is signed where spilled, and each object carries the

   .note.gnu.property the linker needs, else it drops the protection for the

   whole image. Hint encodings need no .arch extension. No leaf signing. */

#if defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT == 1)

#  define GNU_PROPERTY_AARCH64_BTI (1 << 0)

#  define AARCH64_VALID_CALL_TARGET hint #34        /* bti c */

#else

#  define GNU_PROPERTY_AARCH64_BTI 0

#  define AARCH64_VALID_CALL_TARGET

#endif

#if defined(__ARM_FEATURE_PAC_DEFAULT)

#  if (__ARM_FEATURE_PAC_DEFAULT & (1 << 0))         /* key A */

#    define AARCH64_SIGN_LINK_REGISTER     hint #25  /* paciasp */

#    define AARCH64_VALIDATE_LINK_REGISTER hint #29  /* autiasp */

#  elif (__ARM_FEATURE_PAC_DEFAULT & (1 << 1))       /* key B */

#    define AARCH64_SIGN_LINK_REGISTER     hint #27  /* pacibsp */

#    define AARCH64_VALIDATE_LINK_REGISTER hint #31  /* autibsp */

#  else

#    error "__ARM_FEATURE_PAC_DEFAULT selects no key"

#  endif

#  define GNU_PROPERTY_AARCH64_PAC (1 << 1)

#else

#  define GNU_PROPERTY_AARCH64_PAC 0

#  define AARCH64_SIGN_LINK_REGISTER

#  define AARCH64_VALIDATE_LINK_REGISTER

#endif

#if defined(__ARM_FEATURE_GCS_DEFAULT) && (__ARM_FEATURE_GCS_DEFAULT == 1)

#  define GNU_PROPERTY_AARCH64_GCS (1 << 2)

#else

#  define GNU_PROPERTY_AARCH64_GCS 0

#endif

#if defined(__ELF__) && \

    (GNU_PROPERTY_AARCH64_BTI | GNU_PROPERTY_AARCH64_PAC | GNU_PROPERTY_AARCH64_GCS)

        .pushsection .note.gnu.property, "a"

        .balign 8

        .long   4                       /* n_namesz */

        .long   0x10                    /* n_descsz */

        .long   0x5                     /* NT_GNU_PROPERTY_TYPE_0 */

        .asciz  "GNU"

        .long   0xc0000000              /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */

        .long   4

        .long   (GNU_PROPERTY_AARCH64_BTI | GNU_PROPERTY_AARCH64_PAC | GNU_PROPERTY_AARCH64_GCS)

        .long   0

        .popsection

#endif

        .macro  function name, export=1, align=4

        .text

        .align  \align

        .if \export

        .global EXTERN_ASM\name

/* Global for the C glue but not part of libopus's ABI: the C code is built

   with -fvisibility=hidden, so match it here. */

#ifdef __ELF__

        .type   EXTERN_ASM\name, %function

        .hidden EXTERN_ASM\name

#elif defined(__APPLE__)

        .private_extern EXTERN_ASM\name

#endif

EXTERN_ASM\name\():

        AARCH64_VALID_CALL_TARGET

        .else

\name\():

        .endif

        .endm

        .macro  endfunc name

#ifdef __ELF__

        .size   EXTERN_ASM\name, . - EXTERN_ASM\name

#endif

        .endm

        .macro  const name, align=4

#ifdef __MACH__

        .const_data

#else

        .section .rodata

#endif

        .align  \align

\name\():

        .endm

        .macro  endconst name

#ifdef __ELF__

        .size   \name, . - \name

#endif

        .text

        .endm

/* movrel rd, sym[, off] : address of a local symbol (ELF :lo12: / Apple @PAGE). */

        .macro  movrel rd, val, offset=0

#if defined(__APPLE__)

        adrp    \rd, \val+(\offset)@PAGE

        add     \rd, \rd, \val+(\offset)@PAGEOFF

#else

        adrp    \rd, \val+(\offset)

        add     \rd, \rd, :lo12:\val+(\offset)

#endif

        .endm

#endif /* CELT_ARM_ASM_H */