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  • Re: [gentoo-dev] [PATCH 1/3] meson.eclass: wire up LTO support directly

    From Mike Gilbert@21:1/5 to eschwartz93@gmail.com on Tue Feb 20 07:00:01 2024
    On Mon, Feb 19, 2024 at 11:26 PM Eli Schwartz <eschwartz93@gmail.com> wrote:

    meson's builtin LTO support allows meson to introspect whether LTO is
    enabled and do some fancy things, such as forcing LTO off for a single
    target that is known to be special(ly bad) and not support LTO.

    Please make sure to test this change with a multilib-enabled ebuild
    with multiple ABIs enabled. I suspect the filter-lto call will cause
    differing results for the ABIs after the first.

    If that is the case, we may need to declare the relevant FLAGS
    variables with "local -x".

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  • From Sam James@21:1/5 to Eli Schwartz on Tue Feb 20 07:50:01 2024
    Eli Schwartz <eschwartz93@gmail.com> writes:

    [[PGP Signed Part:Undecided]]
    On 2/20/24 1:24 AM, Mike Gilbert wrote:
    I'm afraid I get different results. Build log attached. Happy to help
    figure this out tomorrow.

    To test, I applied this patch and ran this:

    ABI_X86="32 x32 64" CFLAGS="-O2 -pipe -march=amdfam10 -flto=2" ebuild
    zstd-1.5.5-r1.ebuild clean configure


    Yikes. I wonder if this is also a problem for ffmpeg:

    multilib_src_configure() {

    [...]

    # LTO support, bug #566282, bug #754654, bug #772854
    if [[ ${ABI} != x86 ]] && tc-is-lto; then
    # Respect -flto value, e.g -flto=thin
    local v="$(get-flag flto)"
    [[ -n ${v} ]] && myconf+=( "--enable-lto=${v}" ) || myconf+=( "--enable-lto" )
    fi
    filter-lto

    It is indeed.. https://bugs.gentoo.org/923491.

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