On Mon, Nov 20, 2023 at 03:46:06PM +0000, Richard Sandiford wrote:
> Andrew Carlotti <andrew.carlo...@arm.com> writes:
> > This is added to enable function multiversioning, but can also be used
> > directly. The interface is chosen to match that used in LLVM's
> > compiler-rt, to facilitate cross-compiler compatibility.
> >
> > The content of the patch is derived almost entirely from Pavel's prior
> > contributions to compiler-rt/lib/builtins/cpu_model.c. I have made minor
> > changes to align more closely with GCC coding style, and to exclude any code
> > from other LLVM contributors, and am adding this to GCC with Pavel's
> > approval.
> >
> > libgcc/ChangeLog:
> >
> > * config/aarch64/t-aarch64: Include cpuinfo.c
> > * config/aarch64/cpuinfo.c: New file
> > (__init_cpu_features_constructor) New.
> > (__init_cpu_features_resolver) New.
> > (__init_cpu_features) New.
>
> OK on the basis that you mentioed in the covering note: we can deal
> with fixes incrementally. One question though...
> >
> > Co-authored-by: Pavel Iliin <pavel.il...@arm.com>
> >
> >
> > diff --git a/libgcc/config/aarch64/cpuinfo.c
> > b/libgcc/config/aarch64/cpuinfo.c
> > new file mode 100644
> > index
> > 0000000000000000000000000000000000000000..0888ca4ed058430f524b99cb0e204bd996fa0e55
> > --- /dev/null
> > +++ b/libgcc/config/aarch64/cpuinfo.c
> > @@ -0,0 +1,502 @@
> > +/* CPU feature detection for AArch64 architecture.
> > + Copyright (C) 2023 Free Software Foundation, Inc.
> > +
> > + This file is part of GCC.
> > +
> > + This file is free software; you can redistribute it and/or modify it
> > + under the terms of the GNU General Public License as published by the
> > + Free Software Foundation; either version 3, or (at your option) any
> > + later version.
> > +
> > + This file is distributed in the hope that it will be useful, but
> > + WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + General Public License for more details.
> > +
> > + Under Section 7 of GPL version 3, you are granted additional
> > + permissions described in the GCC Runtime Library Exception, version
> > + 3.1, as published by the Free Software Foundation.
> > +
> > + You should have received a copy of the GNU General Public License and
> > + a copy of the GCC Runtime Library Exception along with this program;
> > + see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
> > + <http://www.gnu.org/licenses/>. */
> > +
> > +#if defined(__has_include)
>
> Is this protecting against a known condition? libgcc has to be built
> with the associated version of GCC, so it might be better to drop the
> #if and get a noisy failure if something unexpected happens. That can
> be part of 5/5 though.
>
> Thanks,
> Richard
I don't know that this is required, so I'll assume it isn't. I'll drop it in
the next version of this patch.
> > +#if __has_include(<sys/auxv.h>)
> > +#include <sys/auxv.h>
> > +
> > +#if __has_include(<sys/ifunc.h>)
> > +#include <sys/ifunc.h>
> > +#else
> > +typedef struct __ifunc_arg_t {
> > + unsigned long _size;
> > + unsigned long _hwcap;
> > + unsigned long _hwcap2;
> > +} __ifunc_arg_t;
> > +#endif
> > +
> > +#if __has_include(<asm/hwcap.h>)
> > +#include <asm/hwcap.h>
> > +
> > +/* CPUFeatures must correspond to the same AArch64 features in aarch64.cc
> > */
> > +enum CPUFeatures {
> > + FEAT_RNG,
> > + FEAT_FLAGM,
> > + FEAT_FLAGM2,
> > + FEAT_FP16FML,
> > + FEAT_DOTPROD,
> > + FEAT_SM4,
> > + FEAT_RDM,
> > + FEAT_LSE,
> > + FEAT_FP,
> > + FEAT_SIMD,
> > + FEAT_CRC,
> > + FEAT_SHA1,
> > + FEAT_SHA2,
> > + FEAT_SHA3,
> > + FEAT_AES,
> > + FEAT_PMULL,
> > + FEAT_FP16,
> > + FEAT_DIT,
> > + FEAT_DPB,
> > + FEAT_DPB2,
> > + FEAT_JSCVT,
> > + FEAT_FCMA,
> > + FEAT_RCPC,
> > + FEAT_RCPC2,
> > + FEAT_FRINTTS,
> > + FEAT_DGH,
> > + FEAT_I8MM,
> > + FEAT_BF16,
> > + FEAT_EBF16,
> > + FEAT_RPRES,
> > + FEAT_SVE,
> > + FEAT_SVE_BF16,
> > + FEAT_SVE_EBF16,
> > + FEAT_SVE_I8MM,
> > + FEAT_SVE_F32MM,
> > + FEAT_SVE_F64MM,
> > + FEAT_SVE2,
> > + FEAT_SVE_AES,
> > + FEAT_SVE_PMULL128,
> > + FEAT_SVE_BITPERM,
> > + FEAT_SVE_SHA3,
> > + FEAT_SVE_SM4,
> > + FEAT_SME,
> > + FEAT_MEMTAG,
> > + FEAT_MEMTAG2,
> > + FEAT_MEMTAG3,
> > + FEAT_SB,
> > + FEAT_PREDRES,
> > + FEAT_SSBS,
> > + FEAT_SSBS2,
> > + FEAT_BTI,
> > + FEAT_LS64,
> > + FEAT_LS64_V,
> > + FEAT_LS64_ACCDATA,
> > + FEAT_WFXT,
> > + FEAT_SME_F64,
> > + FEAT_SME_I64,
> > + FEAT_SME2,
> > + FEAT_RCPC3,
> > + FEAT_MAX,
> > + FEAT_EXT = 62, /* Reserved to indicate presence of additional features
> > field
> > + in __aarch64_cpu_features. */
> > + FEAT_INIT /* Used as flag of features initialization completion. */
> > +};
> > +
> > +/* Architecture features used in Function Multi Versioning. */
> > +struct {
> > + unsigned long long features;
> > + /* As features grows new fields could be added. */
> > +} __aarch64_cpu_features __attribute__((visibility("hidden"), nocommon));
> > +
> > +#ifndef _IFUNC_ARG_HWCAP
> > +#define _IFUNC_ARG_HWCAP (1ULL << 62)
> > +#endif
> > +#ifndef AT_HWCAP
> > +#define AT_HWCAP 16
> > +#endif
> > +#ifndef HWCAP_CPUID
> > +#define HWCAP_CPUID (1 << 11)
> > +#endif
> > +#ifndef HWCAP_FP
> > +#define HWCAP_FP (1 << 0)
> > +#endif
> > +#ifndef HWCAP_ASIMD
> > +#define HWCAP_ASIMD (1 << 1)
> > +#endif
> > +#ifndef HWCAP_AES
> > +#define HWCAP_AES (1 << 3)
> > +#endif
> > +#ifndef HWCAP_PMULL
> > +#define HWCAP_PMULL (1 << 4)
> > +#endif
> > +#ifndef HWCAP_SHA1
> > +#define HWCAP_SHA1 (1 << 5)
> > +#endif
> > +#ifndef HWCAP_SHA2
> > +#define HWCAP_SHA2 (1 << 6)
> > +#endif
> > +#ifndef HWCAP_ATOMICS
> > +#define HWCAP_ATOMICS (1 << 8)
> > +#endif
> > +#ifndef HWCAP_FPHP
> > +#define HWCAP_FPHP (1 << 9)
> > +#endif
> > +#ifndef HWCAP_ASIMDHP
> > +#define HWCAP_ASIMDHP (1 << 10)
> > +#endif
> > +#ifndef HWCAP_ASIMDRDM
> > +#define HWCAP_ASIMDRDM (1 << 12)
> > +#endif
> > +#ifndef HWCAP_JSCVT
> > +#define HWCAP_JSCVT (1 << 13)
> > +#endif
> > +#ifndef HWCAP_FCMA
> > +#define HWCAP_FCMA (1 << 14)
> > +#endif
> > +#ifndef HWCAP_LRCPC
> > +#define HWCAP_LRCPC (1 << 15)
> > +#endif
> > +#ifndef HWCAP_DCPOP
> > +#define HWCAP_DCPOP (1 << 16)
> > +#endif
> > +#ifndef HWCAP_SHA3
> > +#define HWCAP_SHA3 (1 << 17)
> > +#endif
> > +#ifndef HWCAP_SM3
> > +#define HWCAP_SM3 (1 << 18)
> > +#endif
> > +#ifndef HWCAP_SM4
> > +#define HWCAP_SM4 (1 << 19)
> > +#endif
> > +#ifndef HWCAP_ASIMDDP
> > +#define HWCAP_ASIMDDP (1 << 20)
> > +#endif
> > +#ifndef HWCAP_SHA512
> > +#define HWCAP_SHA512 (1 << 21)
> > +#endif
> > +#ifndef HWCAP_SVE
> > +#define HWCAP_SVE (1 << 22)
> > +#endif
> > +#ifndef HWCAP_ASIMDFHM
> > +#define HWCAP_ASIMDFHM (1 << 23)
> > +#endif
> > +#ifndef HWCAP_DIT
> > +#define HWCAP_DIT (1 << 24)
> > +#endif
> > +#ifndef HWCAP_ILRCPC
> > +#define HWCAP_ILRCPC (1 << 26)
> > +#endif
> > +#ifndef HWCAP_FLAGM
> > +#define HWCAP_FLAGM (1 << 27)
> > +#endif
> > +#ifndef HWCAP_SSBS
> > +#define HWCAP_SSBS (1 << 28)
> > +#endif
> > +#ifndef HWCAP_SB
> > +#define HWCAP_SB (1 << 29)
> > +#endif
> > +
> > +#ifndef HWCAP2_DCPODP
> > +#define HWCAP2_DCPODP (1 << 0)
> > +#endif
> > +#ifndef HWCAP2_SVE2
> > +#define HWCAP2_SVE2 (1 << 1)
> > +#endif
> > +#ifndef HWCAP2_SVEAES
> > +#define HWCAP2_SVEAES (1 << 2)
> > +#endif
> > +#ifndef HWCAP2_SVEPMULL
> > +#define HWCAP2_SVEPMULL (1 << 3)
> > +#endif
> > +#ifndef HWCAP2_SVEBITPERM
> > +#define HWCAP2_SVEBITPERM (1 << 4)
> > +#endif
> > +#ifndef HWCAP2_SVESHA3
> > +#define HWCAP2_SVESHA3 (1 << 5)
> > +#endif
> > +#ifndef HWCAP2_SVESM4
> > +#define HWCAP2_SVESM4 (1 << 6)
> > +#endif
> > +#ifndef HWCAP2_FLAGM2
> > +#define HWCAP2_FLAGM2 (1 << 7)
> > +#endif
> > +#ifndef HWCAP2_FRINT
> > +#define HWCAP2_FRINT (1 << 8)
> > +#endif
> > +#ifndef HWCAP2_SVEI8MM
> > +#define HWCAP2_SVEI8MM (1 << 9)
> > +#endif
> > +#ifndef HWCAP2_SVEF32MM
> > +#define HWCAP2_SVEF32MM (1 << 10)
> > +#endif
> > +#ifndef HWCAP2_SVEF64MM
> > +#define HWCAP2_SVEF64MM (1 << 11)
> > +#endif
> > +#ifndef HWCAP2_SVEBF16
> > +#define HWCAP2_SVEBF16 (1 << 12)
> > +#endif
> > +#ifndef HWCAP2_I8MM
> > +#define HWCAP2_I8MM (1 << 13)
> > +#endif
> > +#ifndef HWCAP2_BF16
> > +#define HWCAP2_BF16 (1 << 14)
> > +#endif
> > +#ifndef HWCAP2_DGH
> > +#define HWCAP2_DGH (1 << 15)
> > +#endif
> > +#ifndef HWCAP2_RNG
> > +#define HWCAP2_RNG (1 << 16)
> > +#endif
> > +#ifndef HWCAP2_BTI
> > +#define HWCAP2_BTI (1 << 17)
> > +#endif
> > +#ifndef HWCAP2_MTE
> > +#define HWCAP2_MTE (1 << 18)
> > +#endif
> > +#ifndef HWCAP2_RPRES
> > +#define HWCAP2_RPRES (1 << 21)
> > +#endif
> > +#ifndef HWCAP2_MTE3
> > +#define HWCAP2_MTE3 (1 << 22)
> > +#endif
> > +#ifndef HWCAP2_SME
> > +#define HWCAP2_SME (1 << 23)
> > +#endif
> > +#ifndef HWCAP2_SME_I16I64
> > +#define HWCAP2_SME_I16I64 (1 << 24)
> > +#endif
> > +#ifndef HWCAP2_SME_F64F64
> > +#define HWCAP2_SME_F64F64 (1 << 25)
> > +#endif
> > +#ifndef HWCAP2_WFXT
> > +#define HWCAP2_WFXT (1UL << 31)
> > +#endif
> > +#ifndef HWCAP2_EBF16
> > +#define HWCAP2_EBF16 (1UL << 32)
> > +#endif
> > +#ifndef HWCAP2_SVE_EBF16
> > +#define HWCAP2_SVE_EBF16 (1UL << 33)
> > +#endif
> > +
> > +static void
> > +__init_cpu_features_constructor(unsigned long hwcap,
> > + const __ifunc_arg_t *arg) {
> > +#define setCPUFeature(F) __aarch64_cpu_features.features |= 1ULL << F
> > +#define getCPUFeature(id, ftr) __asm__("mrs %0, " #id : "=r"(ftr))
> > +#define extractBits(val, start, number) \
> > + (val & ((1ULL << number) - 1ULL) << start) >> start
> > + unsigned long hwcap2 = 0;
> > + if (hwcap & _IFUNC_ARG_HWCAP)
> > + hwcap2 = arg->_hwcap2;
> > + if (hwcap & HWCAP_CRC32)
> > + setCPUFeature(FEAT_CRC);
> > + if (hwcap & HWCAP_PMULL)
> > + setCPUFeature(FEAT_PMULL);
> > + if (hwcap & HWCAP_FLAGM)
> > + setCPUFeature(FEAT_FLAGM);
> > + if (hwcap2 & HWCAP2_FLAGM2) {
> > + setCPUFeature(FEAT_FLAGM);
> > + setCPUFeature(FEAT_FLAGM2);
> > + }
> > + if (hwcap & HWCAP_SM3 && hwcap & HWCAP_SM4)
> > + setCPUFeature(FEAT_SM4);
> > + if (hwcap & HWCAP_ASIMDDP)
> > + setCPUFeature(FEAT_DOTPROD);
> > + if (hwcap & HWCAP_ASIMDFHM)
> > + setCPUFeature(FEAT_FP16FML);
> > + if (hwcap & HWCAP_FPHP) {
> > + setCPUFeature(FEAT_FP16);
> > + setCPUFeature(FEAT_FP);
> > + }
> > + if (hwcap & HWCAP_DIT)
> > + setCPUFeature(FEAT_DIT);
> > + if (hwcap & HWCAP_ASIMDRDM)
> > + setCPUFeature(FEAT_RDM);
> > + if (hwcap & HWCAP_ILRCPC)
> > + setCPUFeature(FEAT_RCPC2);
> > + if (hwcap & HWCAP_AES)
> > + setCPUFeature(FEAT_AES);
> > + if (hwcap & HWCAP_SHA1)
> > + setCPUFeature(FEAT_SHA1);
> > + if (hwcap & HWCAP_SHA2)
> > + setCPUFeature(FEAT_SHA2);
> > + if (hwcap & HWCAP_JSCVT)
> > + setCPUFeature(FEAT_JSCVT);
> > + if (hwcap & HWCAP_FCMA)
> > + setCPUFeature(FEAT_FCMA);
> > + if (hwcap & HWCAP_SB)
> > + setCPUFeature(FEAT_SB);
> > + if (hwcap & HWCAP_SSBS)
> > + setCPUFeature(FEAT_SSBS2);
> > + if (hwcap2 & HWCAP2_MTE) {
> > + setCPUFeature(FEAT_MEMTAG);
> > + setCPUFeature(FEAT_MEMTAG2);
> > + }
> > + if (hwcap2 & HWCAP2_MTE3) {
> > + setCPUFeature(FEAT_MEMTAG);
> > + setCPUFeature(FEAT_MEMTAG2);
> > + setCPUFeature(FEAT_MEMTAG3);
> > + }
> > + if (hwcap2 & HWCAP2_SVEAES)
> > + setCPUFeature(FEAT_SVE_AES);
> > + if (hwcap2 & HWCAP2_SVEPMULL) {
> > + setCPUFeature(FEAT_SVE_AES);
> > + setCPUFeature(FEAT_SVE_PMULL128);
> > + }
> > + if (hwcap2 & HWCAP2_SVEBITPERM)
> > + setCPUFeature(FEAT_SVE_BITPERM);
> > + if (hwcap2 & HWCAP2_SVESHA3)
> > + setCPUFeature(FEAT_SVE_SHA3);
> > + if (hwcap2 & HWCAP2_SVESM4)
> > + setCPUFeature(FEAT_SVE_SM4);
> > + if (hwcap2 & HWCAP2_DCPODP)
> > + setCPUFeature(FEAT_DPB2);
> > + if (hwcap & HWCAP_ATOMICS)
> > + setCPUFeature(FEAT_LSE);
> > + if (hwcap2 & HWCAP2_RNG)
> > + setCPUFeature(FEAT_RNG);
> > + if (hwcap2 & HWCAP2_I8MM)
> > + setCPUFeature(FEAT_I8MM);
> > + if (hwcap2 & HWCAP2_EBF16)
> > + setCPUFeature(FEAT_EBF16);
> > + if (hwcap2 & HWCAP2_SVE_EBF16)
> > + setCPUFeature(FEAT_SVE_EBF16);
> > + if (hwcap2 & HWCAP2_DGH)
> > + setCPUFeature(FEAT_DGH);
> > + if (hwcap2 & HWCAP2_FRINT)
> > + setCPUFeature(FEAT_FRINTTS);
> > + if (hwcap2 & HWCAP2_SVEI8MM)
> > + setCPUFeature(FEAT_SVE_I8MM);
> > + if (hwcap2 & HWCAP2_SVEF32MM)
> > + setCPUFeature(FEAT_SVE_F32MM);
> > + if (hwcap2 & HWCAP2_SVEF64MM)
> > + setCPUFeature(FEAT_SVE_F64MM);
> > + if (hwcap2 & HWCAP2_BTI)
> > + setCPUFeature(FEAT_BTI);
> > + if (hwcap2 & HWCAP2_RPRES)
> > + setCPUFeature(FEAT_RPRES);
> > + if (hwcap2 & HWCAP2_WFXT)
> > + setCPUFeature(FEAT_WFXT);
> > + if (hwcap2 & HWCAP2_SME)
> > + setCPUFeature(FEAT_SME);
> > + if (hwcap2 & HWCAP2_SME_I16I64)
> > + setCPUFeature(FEAT_SME_I64);
> > + if (hwcap2 & HWCAP2_SME_F64F64)
> > + setCPUFeature(FEAT_SME_F64);
> > + if (hwcap & HWCAP_CPUID) {
> > + unsigned long ftr;
> > + getCPUFeature(ID_AA64PFR1_EL1, ftr);
> > + /* ID_AA64PFR1_EL1.MTE >= 0b0001 */
> > + if (extractBits(ftr, 8, 4) >= 0x1)
> > + setCPUFeature(FEAT_MEMTAG);
> > + /* ID_AA64PFR1_EL1.SSBS == 0b0001 */
> > + if (extractBits(ftr, 4, 4) == 0x1)
> > + setCPUFeature(FEAT_SSBS);
> > + /* ID_AA64PFR1_EL1.SME == 0b0010 */
> > + if (extractBits(ftr, 24, 4) == 0x2)
> > + setCPUFeature(FEAT_SME2);
> > + getCPUFeature(ID_AA64PFR0_EL1, ftr);
> > + /* ID_AA64PFR0_EL1.FP != 0b1111 */
> > + if (extractBits(ftr, 16, 4) != 0xF) {
> > + setCPUFeature(FEAT_FP);
> > + /* ID_AA64PFR0_EL1.AdvSIMD has the same value as ID_AA64PFR0_EL1.FP
> > */
> > + setCPUFeature(FEAT_SIMD);
> > + }
> > + /* ID_AA64PFR0_EL1.SVE != 0b0000 */
> > + if (extractBits(ftr, 32, 4) != 0x0) {
> > + /* get ID_AA64ZFR0_EL1, that name supported if sve enabled only */
> > + getCPUFeature(S3_0_C0_C4_4, ftr);
> > + /* ID_AA64ZFR0_EL1.SVEver == 0b0000 */
> > + if (extractBits(ftr, 0, 4) == 0x0)
> > + setCPUFeature(FEAT_SVE);
> > + /* ID_AA64ZFR0_EL1.SVEver == 0b0001 */
> > + if (extractBits(ftr, 0, 4) == 0x1)
> > + setCPUFeature(FEAT_SVE2);
> > + /* ID_AA64ZFR0_EL1.BF16 != 0b0000 */
> > + if (extractBits(ftr, 20, 4) != 0x0)
> > + setCPUFeature(FEAT_SVE_BF16);
> > + }
> > + getCPUFeature(ID_AA64ISAR0_EL1, ftr);
> > + /* ID_AA64ISAR0_EL1.SHA3 != 0b0000 */
> > + if (extractBits(ftr, 32, 4) != 0x0)
> > + setCPUFeature(FEAT_SHA3);
> > + getCPUFeature(ID_AA64ISAR1_EL1, ftr);
> > + /* ID_AA64ISAR1_EL1.DPB >= 0b0001 */
> > + if (extractBits(ftr, 0, 4) >= 0x1)
> > + setCPUFeature(FEAT_DPB);
> > + /* ID_AA64ISAR1_EL1.LRCPC != 0b0000 */
> > + if (extractBits(ftr, 20, 4) != 0x0)
> > + setCPUFeature(FEAT_RCPC);
> > + /* ID_AA64ISAR1_EL1.LRCPC == 0b0011 */
> > + if (extractBits(ftr, 20, 4) == 0x3)
> > + setCPUFeature(FEAT_RCPC3);
> > + /* ID_AA64ISAR1_EL1.SPECRES == 0b0001 */
> > + if (extractBits(ftr, 40, 4) == 0x2)
> > + setCPUFeature(FEAT_PREDRES);
> > + /* ID_AA64ISAR1_EL1.BF16 != 0b0000 */
> > + if (extractBits(ftr, 44, 4) != 0x0)
> > + setCPUFeature(FEAT_BF16);
> > + /* ID_AA64ISAR1_EL1.LS64 >= 0b0001 */
> > + if (extractBits(ftr, 60, 4) >= 0x1)
> > + setCPUFeature(FEAT_LS64);
> > + /* ID_AA64ISAR1_EL1.LS64 >= 0b0010 */
> > + if (extractBits(ftr, 60, 4) >= 0x2)
> > + setCPUFeature(FEAT_LS64_V);
> > + /* ID_AA64ISAR1_EL1.LS64 >= 0b0011 */
> > + if (extractBits(ftr, 60, 4) >= 0x3)
> > + setCPUFeature(FEAT_LS64_ACCDATA);
> > + } else {
> > + /* Set some features in case of no CPUID support. */
> > + if (hwcap & (HWCAP_FP | HWCAP_FPHP)) {
> > + setCPUFeature(FEAT_FP);
> > + /* FP and AdvSIMD fields have the same value. */
> > + setCPUFeature(FEAT_SIMD);
> > + }
> > + if (hwcap & HWCAP_DCPOP || hwcap2 & HWCAP2_DCPODP)
> > + setCPUFeature(FEAT_DPB);
> > + if (hwcap & HWCAP_LRCPC || hwcap & HWCAP_ILRCPC)
> > + setCPUFeature(FEAT_RCPC);
> > + if (hwcap2 & HWCAP2_BF16 || hwcap2 & HWCAP2_EBF16)
> > + setCPUFeature(FEAT_BF16);
> > + if (hwcap2 & HWCAP2_SVEBF16)
> > + setCPUFeature(FEAT_SVE_BF16);
> > + if (hwcap2 & HWCAP2_SVE2 && hwcap & HWCAP_SVE)
> > + setCPUFeature(FEAT_SVE2);
> > + if (hwcap & HWCAP_SHA3)
> > + setCPUFeature(FEAT_SHA3);
> > + }
> > + setCPUFeature(FEAT_INIT);
> > +}
> > +
> > +void
> > +__init_cpu_features_resolver(unsigned long hwcap, const __ifunc_arg_t
> > *arg) {
> > + if (__aarch64_cpu_features.features)
> > + return;
> > + __init_cpu_features_constructor(hwcap, arg);
> > +}
> > +
> > +void __attribute__ ((constructor))
> > +__init_cpu_features(void) {
> > + unsigned long hwcap;
> > + unsigned long hwcap2;
> > + /* CPU features already initialized. */
> > + if (__aarch64_cpu_features.features)
> > + return;
> > + hwcap = getauxval(AT_HWCAP);
> > + hwcap2 = getauxval(AT_HWCAP2);
> > + __ifunc_arg_t arg;
> > + arg._size = sizeof(__ifunc_arg_t);
> > + arg._hwcap = hwcap;
> > + arg._hwcap2 = hwcap2;
> > + __init_cpu_features_constructor(hwcap | _IFUNC_ARG_HWCAP, &arg);
> > +#undef extractBits
> > +#undef getCPUFeature
> > +#undef setCPUFeature
> > +}
> > +#endif /* __has_include(<asm/hwcap.h>) */
> > +#endif /* __has_include(<sys/auxv.h>) */
> > +#endif /* defined(__has_include) */
> > diff --git a/libgcc/config/aarch64/t-aarch64
> > b/libgcc/config/aarch64/t-aarch64
> > index
> > a40b6241c86ecc4007b5cfd28aa989ee894aa410..8bc1a4ca0c2eb75c17e62a25aa45a875bfd472f8
> > 100644
> > --- a/libgcc/config/aarch64/t-aarch64
> > +++ b/libgcc/config/aarch64/t-aarch64
> > @@ -19,3 +19,4 @@
> > # <http://www.gnu.org/licenses/>.
> >
> > LIB2ADD += $(srcdir)/config/aarch64/sync-cache.c
> > +LIB2ADD += $(srcdir)/config/aarch64/cpuinfo.c
