build/autoconf/arch.m4
author Nick Alexander <nalexander@mozilla.com>
Fri, 12 Oct 2018 22:38:44 +0000
changeset 499408 91300d29898b1a1102e1b62164aeee1f56b2ee86
parent 498056 34ab0ef2419d31981551a98398efe10f4cc3d705
child 527016 7947b90f15808c0de5673831950fe2886558d23c
permissions -rw-r--r--
Bug 1489443 - Set GCC_USE_GNU_LD based on linker kind. r=froydnj The desired outcome of this change is that we'll set `-Wl,--version-script` based on linker kind and not on the output of `$LINKER -v`. This is a cheap way to address a simple problem that has a complicated ideal solution. The underlying issue is that in some situations, when targeting Android, a macOS system `ld` is interrogated to determine if a cross-compiling linker "is GNU ld" and a particular linker feature is set in that situation. The macOS system `ld` doesn't pass the "is GNU ld" test, and the linker feature isn't set; that causes link failures, even though the actual linker has nothing to do with the system `ld`. The ideal solution is to test for linker capabilities dynamically. We do a lot of that in old-configure.in, and we don't do any of that in toolchain.configure. Rather than start testing in toolchain.configure, we hard-code: a cheap solution to the immediate problem. Differential Revision: https://phabricator.services.mozilla.com/D8471

dnl This Source Code Form is subject to the terms of the Mozilla Public
dnl License, v. 2.0. If a copy of the MPL was not distributed with this
dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.

AC_DEFUN([MOZ_ARCH_OPTS],
[

dnl ========================================================
dnl = ARM toolchain tweaks
dnl ========================================================

MOZ_THUMB=toolchain-default
MOZ_THUMB_INTERWORK=toolchain-default
MOZ_FPU=toolchain-default
MOZ_FLOAT_ABI=toolchain-default
MOZ_SOFT_FLOAT=toolchain-default
MOZ_ALIGN=toolchain-default

MOZ_ARG_WITH_STRING(arch,
[  --with-arch=[[type|toolchain-default]]
                           Use specific CPU features (-march=type). Resets
                           thumb, fpu, float-abi, etc. defaults when set],
    if test -z "$GNU_CC"; then
        AC_MSG_ERROR([--with-arch is not supported on non-GNU toolchains])
    fi
    MOZ_ARCH=$withval)

if test -z "$MOZ_ARCH"; then
    dnl Defaults
    case "${CPU_ARCH}-${OS_TARGET}" in
    arm-Android)
        MOZ_THUMB=yes
        MOZ_ARCH=armv7-a
        MOZ_FPU=neon
        MOZ_FLOAT_ABI=softfp
        MOZ_ALIGN=no
        ;;
    arm-Darwin)
        MOZ_ARCH=toolchain-default
        ;;
    esac
fi

if test "$MOZ_ARCH" = "armv6" -a "$OS_TARGET" = "Android"; then
    AC_MSG_ERROR([Android/armv6 is not supported])
fi

MOZ_ARG_WITH_STRING(thumb,
[  --with-thumb[[=yes|no|toolchain-default]]]
[                          Use Thumb instruction set (-mthumb)],
    if test -z "$GNU_CC"; then
        AC_MSG_ERROR([--with-thumb is not supported on non-GNU toolchains])
    fi
    MOZ_THUMB=$withval)

MOZ_ARG_WITH_STRING(thumb-interwork,
[  --with-thumb-interwork[[=yes|no|toolchain-default]]
                           Use Thumb/ARM instuctions interwork (-mthumb-interwork)],
    if test -z "$GNU_CC"; then
        AC_MSG_ERROR([--with-thumb-interwork is not supported on non-GNU toolchains])
    fi
    MOZ_THUMB_INTERWORK=$withval)

MOZ_ARG_WITH_STRING(fpu,
[  --with-fpu=[[type|toolchain-default]]
                           Use specific FPU type (-mfpu=type)],
    if test -z "$GNU_CC"; then
        AC_MSG_ERROR([--with-fpu is not supported on non-GNU toolchains])
    fi
    MOZ_FPU=$withval)

MOZ_ARG_WITH_STRING(float-abi,
[  --with-float-abi=[[type|toolchain-default]]
                           Use specific arm float ABI (-mfloat-abi=type)],
    if test -z "$GNU_CC"; then
        AC_MSG_ERROR([--with-float-abi is not supported on non-GNU toolchains])
    fi
    MOZ_FLOAT_ABI=$withval)

MOZ_ARG_WITH_STRING(soft-float,
[  --with-soft-float[[=yes|no|toolchain-default]]
                           Use soft float library (-msoft-float)],
    if test -z "$GNU_CC"; then
        AC_MSG_ERROR([--with-soft-float is not supported on non-GNU toolchains])
    fi
    MOZ_SOFT_FLOAT=$withval)

case "$MOZ_ARCH" in
toolchain-default|"")
    arch_flag=""
    ;;
*)
    arch_flag="-march=$MOZ_ARCH"
    ;;
esac

case "$MOZ_THUMB" in
yes)
    MOZ_THUMB2=1
    thumb_flag="-mthumb"
    ;;
no)
    MOZ_THUMB2=
    thumb_flag="-marm"
    ;;
*)
    _SAVE_CFLAGS="$CFLAGS"
    CFLAGS="$arch_flag"
    AC_TRY_COMPILE([],[return sizeof(__thumb2__);],
        MOZ_THUMB2=1,
        MOZ_THUMB2=)
    CFLAGS="$_SAVE_CFLAGS"
    thumb_flag=""
    ;;
esac

if test "$MOZ_THUMB2" = 1; then
    AC_DEFINE(MOZ_THUMB2)
fi

case "$MOZ_THUMB_INTERWORK" in
yes)
    thumb_interwork_flag="-mthumb-interwork"
    ;;
no)
    thumb_interwork_flag="-mno-thumb-interwork"
    ;;
*) # toolchain-default
    thumb_interwork_flag=""
    ;;
esac

case "$MOZ_FPU" in
toolchain-default|"")
    fpu_flag=""
    ;;
*)
    fpu_flag="-mfpu=$MOZ_FPU"
    ;;
esac

case "$MOZ_FLOAT_ABI" in
toolchain-default|"")
    float_abi_flag=""
    ;;
*)
    float_abi_flag="-mfloat-abi=$MOZ_FLOAT_ABI"
    ;;
esac

case "$MOZ_SOFT_FLOAT" in
yes)
    soft_float_flag="-msoft-float"
    ;;
no)
    soft_float_flag="-mno-soft-float"
    ;;
*) # toolchain-default
    soft_float_flag=""
    ;;
esac

case "$MOZ_ALIGN" in
no)
    align_flag="-mno-unaligned-access"
    ;;
yes)
    align_flag="-munaligned-access"
    ;;
*)
    align_flag=""
    ;;
esac

if test -n "$align_flag"; then
  _SAVE_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS $align_flag"
  AC_MSG_CHECKING(whether alignment flag ($align_flag) is supported)
  AC_TRY_COMPILE([],[],,align_flag="")
  CFLAGS="$_SAVE_CFLAGS"
fi

dnl Use echo to avoid accumulating space characters
all_flags=`echo $arch_flag $thumb_flag $thumb_interwork_flag $fpu_flag $float_abi_flag $soft_float_flag $align_flag`
if test -n "$all_flags"; then
    _SAVE_CFLAGS="$CFLAGS"
    CFLAGS="$all_flags"
    AC_MSG_CHECKING(whether the chosen combination of compiler flags ($all_flags) works)
    AC_TRY_COMPILE([],[return 0;],
        AC_MSG_RESULT([yes]),
        AC_MSG_ERROR([no]))

    CFLAGS="$_SAVE_CFLAGS $all_flags"
    CXXFLAGS="$CXXFLAGS $all_flags"
    ASFLAGS="$ASFLAGS $all_flags"
    if test -n "$thumb_flag"; then
        LDFLAGS="$LDFLAGS $thumb_flag"
    fi
fi

AC_SUBST(MOZ_THUMB2)

if test "$CPU_ARCH" = "arm"; then
  NEON_FLAGS="-mfpu=neon"
  AC_MSG_CHECKING(for ARM SIMD support in compiler)
  # We try to link so that this also fails when
  # building with LTO.
  AC_TRY_LINK([],
                 [asm("uqadd8 r1, r1, r2");],
                 result="yes", result="no")
  AC_MSG_RESULT("$result")
  if test "$result" = "yes"; then
      AC_DEFINE(HAVE_ARM_SIMD)
      HAVE_ARM_SIMD=1
  fi

  AC_MSG_CHECKING(ARM version support in compiler)
  dnl Determine the target ARM architecture (5 for ARMv5, v5T, v5E, etc.; 6 for ARMv6, v6K, etc.)
  ARM_ARCH=`${CC-cc} ${CFLAGS} -dM -E - < /dev/null | sed -n 's/.*__ARM_ARCH_\([[0-9]][[0-9]]*\).*/\1/p' | head -n 1`
  AC_MSG_RESULT("$ARM_ARCH")

  AC_MSG_CHECKING(for ARM NEON support in compiler)
  # We try to link so that this also fails when
  # building with LTO.
  AC_TRY_LINK([],
                 [asm(".fpu neon\n vadd.i8 d0, d0, d0");],
                 result="yes", result="no")
  AC_MSG_RESULT("$result")
  if test "$result" = "yes"; then
      AC_DEFINE(HAVE_ARM_NEON)
      HAVE_ARM_NEON=1

      dnl We don't need to build NEON support if we're targetting a non-NEON device.
      dnl This matches media/webrtc/trunk/webrtc/build/common.gypi.
      if test -n "$ARM_ARCH"; then
          if test "$ARM_ARCH" -lt 7; then
              BUILD_ARM_NEON=
          else
              AC_DEFINE(BUILD_ARM_NEON)
              BUILD_ARM_NEON=1
          fi
      fi
  fi

  dnl Building with -mfpu=neon requires either the "softfp" or the
  dnl "hardfp" ABI. Depending on the compiler's default target, and the
  dnl CFLAGS, the default ABI might be neither, in which case it is the
  dnl "softfloat" ABI.
  dnl The "softfloat" ABI is binary-compatible with the "softfp" ABI, so
  dnl we can safely mix code built with both ABIs. So, if we detect
  dnl that compiling uses the "softfloat" ABI, force the use of the
  dnl "softfp" ABI instead.
  dnl Confusingly, the __SOFTFP__ preprocessor variable indicates the
  dnl "softfloat" ABI, not the "softfp" ABI.
  dnl Note: VPX_ASFLAGS is also used in CFLAGS.
  AC_TRY_COMPILE([],
    [#ifndef __SOFTFP__
     #error "compiler target supports -mfpu=neon, so we don't have to add extra flags"
     #endif],
     NEON_FLAGS="$NEON_FLAGS -mfloat-abi=softfp"
  )

fi # CPU_ARCH = arm

AC_SUBST(HAVE_ARM_SIMD)
AC_SUBST(HAVE_ARM_NEON)
AC_SUBST(BUILD_ARM_NEON)
AC_SUBST(ARM_ARCH)
AC_SUBST_LIST(NEON_FLAGS)
AC_SUBST(MOZ_FPU)

])